Assessment of Tanzania Magnesite’s Suitability for the Struvite Recovery and Other Industrial Applications

Assessment of Tanzania Magnesite’s Suitability for the Struvite Recovery and Other Industrial Applications | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Assessment of Tanzania Magnesite’s Suitability for the Struvite Recovery and Other Industrial Applications Daniel Tsingay Illakwahhi, Maheswara Rao Vegi, Bajarang Bali Lal Srivastava This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4128932/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 23 Jul, 2024 Read the published version in Carbonates and Evaporites → Version 1 posted 10 You are reading this latest preprint version Abstract Magnesite (MgCO 3 ) is a valuable mineral with wide industrial applications; thus, geochemical familiarity and deposit quality are critical for making the best use of these resources. Tanzania is reported to have magnesite deposits in at least 12 different locations; however, four of these were chosen at random for study. This study aimed to examine the mineralogical and elemental composition of rock samples from Chambogo (KL), Muriatata (AR), Lobolosoiti (MN), and Chikaza (DM) using x-ray fluorescence (XRF) and powder x-ray diffraction (XRD). XRF examination revealed that sample KL, AR, MN, and DM, respectively, contain 45.21%, 46.06%, 43.21%, and 43.21% of magnesium oxide. Besides MgO, all samples contained SiO 2 , Fe 2 O 3 , Al 2 O 3 , CaO and several trace elements as impurities, with only calcium oxide, iron, arsenic and chromium identified as impurities of concern. However, XRD analysis indicated magnesite as the major mineral phase in samples KL, AR, MN, and DM, with percentage concentrations of 65.2, 68.14, 63.87, and 68, respectively. In all samples, strong peaks at 2θ~ 33 o , 43 o , 54 o and 55 o , confirmed the crystalline nature of magnesite. Calcination of these samples however, resulted in peak shift and phase change, with main diffraction peaks generated at 2θ~ 36.9 o , 42.9 o and 62.3 o , confirming the formation of crystalline MgO. Despite considerable contamination levels of CaO, iron, chromium, and arsenic in the samples, all samples had enough magnesite to be mined for industrial use. magnesite minerals struvite deposits XRF XRD Figures Figure 1 Figure 2 Figure 3 1. Introduction Magnesite is a carbonate mineral with a general formula of MgCO 3 . It is considered as a member of the calcite group of carbonate minerals that is a principal source of magnesium (Beyecha, 2016); Shand (2006). The mineral has the same crystal structure as calcite, a calcium carbonate with a hardness and texture similar to white magnesite and marble (Chen & Tao, 2004; Misch, 2012; Pluch, 2018; Siegesmund & Török, 2010). In its natural state, magnesite exists as a white, gray, or brown porous crystal (Chauke, 2020; Shand, 2006). Magnesite's physical appearance ranges from translucent to opaque, with variable amounts of carbonates and oxides of iron, calcium, manganese, and aluminum silicates giving it a milky-white appearance (Chauke, 2020). However, the majority of its reserves in Tanzania from which the samples used in this study are taken are milky-white deposits. Magnesite is formed through carbonation of magnesium-rich rocks such as peridotite or serpentine during regional contact, or hydrothermal metamorphism, particularly when exposed to carbon dioxide-rich water (Efe et al., 2020; Pilchin, 2011). Magnesite formed in this manner is sometimes cryptocrystalline and contains a significant amount of chert. Since olivine is the most dominant mineral in peridotite, it is olivine which is carbonated (Grozeva et al., 2017; Hövelmann et al., 2012; Kelemen et al., 2011; Sissmann et al., 2014). It can also form as a result of the alteration of limestone, dolomite, marble, or any other carbonate-rich rock by magnesium-rich solutions during regional contact, or hydrothermal metamorphism (Meng et al., 2019; Rajendran et al., 2013). It might be formed in the regolith above weathering ultramafic rocks and other magnesium-rich rocks (Kelemen et al., 2011). Carbonic acid in subsurface waters promotes this formation, which frequently results in nodular magnesite. This geological process may result in to the formation of magnesite of high purity. Magnesite could even form as a secondary mineral as a result of precipitation in veins and fractures that cut through carbonate and ultramafic rocks (Azer et al., 2019; Chauke, 2020). Moreover, magnesite is often silicified or mixed with chert, marking it deceptive hard. It produces effervescence when treated with HCl, which is used as a litmus test; however, the presence of chert reduces the apparent effervescence with HCl. Magnesite can be found in many different places and countries around the world. Currently, the largest producer of magnesite as well as the country with the most deposits is China (Drnek et al., 2018; Efe et al., 2020). According to USGS, Russia, USA, Australia, Austria, Greece, Spain, Slovakia, Brazil, and Turkey are other nations with sizable magnesite reserves beside China (Merrill, 2022). Nevertheless, Russian reserves make up the majority. In addition, Tanzania is home to numerous magnesite deposits found in different regions. According to the Geological Survey of Tanzania (GST) (2018), there are currently twelve locations with known magnesite deposits located in six regions. The magnesite deposit at Chambogo in Same district, Kilimanjaro region, is currently being mined for commercial purposes, while the excavation process at Muriatata had just begun. Magnesite on heating produces magnesia (MgO), the chemical used to make high heat resistant bricks used to line kilns, industrial ovens, incinerators and blast furnaces (An et al., 2018; Efe et al., 2020). It is widely used in many industrial areas such as iron-steel, limestone, cement, glass, paper, fuel, printing inks, pharmaceuticals, and stock farming (Abali et al., 2006; Efe et al., 2020; Gulluce et al., 2020; Woodall et al., 2019). Besides, it is used to produce magnesium-based chemicals, fertilizers (Kiani et al., 2019; Krähenbühl et al., 2016) and can even be refined into magnesium metal (Laçin et al., 2005). According to reports (Krähenbühl et al., 2016; X. Li et al., 2021; Zhang et al., 2019), magnesite can also be utilized to recover struvite from waste water. Furthermore, magnesite is commonly used in the production of tumbled stones, beads, and cabochons. White magnesite is a porous mineral; it can therefore be cut and dyed to produce almost any color (Fritsch et al., 2019; Manutchehr-Danai, 2005; Zwaan et al., 2005). However, in Tanzania, magnesia is mined for use primarily in the ceramic, cement, fertilizer, and glass industries. The grade of magnesite rock deposits is affected by magnesium content, impurity types, grain size, crystal structures, formation conditions, porosity, and other mineralogical composition (Alhaddad et al., 2022; Krähenbühl et al., 2016; Pudlo et al., 2012). However, the magnesium amount, impurity levels and types are the most important criteria in determining the grade of magnesite rock. Magnesite has been found to contain impurities such as silicium, iron, and calcium carbonate (Efe et al., 2020; Kelemen et al., 2011). Due to its ability to absorb moisture from the air, magnesite’s calcium carbonate content affects the quality of refractory materials. For example, a study by Efe et al. (2020) reported the impact of calcium carbonate impurities on the quality and economic value of magnesite when used in the production of refractory materials. Elevated levels of heavy metal impurities such as chromium, lead, iron, cadmium, and radioactive elements such as arsenic and uranium might impair magnesite's capacity to be used for struvite recovery and fertilizer production. Moreover, lead, cadmium, iron, arsenic, and uranium have been identified as potentially harmful contaminants in struvite, liming materials, micronutrient fertilizers, and phosphate-based fertilizers (Gonçalves Jr et al., 2014; Gupta et al., 2014; Taylor et al., 2016). Despite the fact that Tanzania has numerous proven magnesite deposits, critical information on quality and geochemical composition is absent due to limited studies. The quality of magnesite deposits can vary significantly from one location to another (Li et al., 2014; Masindi et al., 2016), depending on the geological environments and the dominant minerals in the parent rock (Hojamberdiev et al., 2010; Pohl, 1989). Nevertheless, it is worth noting that this information is important for agricultural and industrial stakeholders. This study however, tries to examine the quality and mineralogical composition of magnesite deposits found in Tanzania. 2. Methodology 2.1 Study Sites Magnesite rocks for this study were mined and collected from four sites found in four regions of Tanzania (Fig. 1). These sites are Chambogo magnesite hill (4°8'7.801" South, 37°48'43.583" East) located in Same district, Kilimanjaro region, Muriatata hill (2°43'49.480" South, 36°29'36.641" East) located in Longido district, Arusha region, Lobolosoiti hill (4°22'28.450" South, 37°28'10.542" East) located in Simanjiro district, Manyara region and Chikaza hill (6°13'39.027" South, 35°58'1.025" East) located in Dodoma Municipal, Dodoma region. 2.2 Sampling Procedure According to Geological Survey of Tanzania (GST), there are twelve magnesite rock/soil deposits found in six regions of Tanzania. To select four regions from which samples were taken, a simple random sampling method was used (Noor et al., 2022; West, 2016). A simple random sampling method was used as well to select a site in regions with more than one location. The procedure entailed writing regions or site names on pieces of paper, placing them in a box, and selecting one name at random. For example, the Dodoma region had four locations, the Arusha region had two, and the Kilimanjaro and Manyara regions each had one. For the samples to be representative, the sites were divided into four quadrat within 50 meter diameter. 2.3 Sample Collection The texture, colors, and effervescence of the rock samples with hydrochloric acid were used as a litmus test for preliminary magnesite identification (You et al., 2015). It should be noted that all metals carbonates react with hydrochloric acid form effervescence. At least 5 kg of rock/soil was extracted at each quadrat along the cardinal directions within 50 meters perimeter; making a total of 20 kg of sample per site. Rock samples from Chambogo, Muriatata, Lobolosoiti and Chikaza were labeled as KL, AR, MN and DM respectively. The samples were then transported to the University of Dodoma for preparation and analysis. 2.4 Samples Preparation The rock samples were thoroughly washed to remove dust and other earthly materials and then sun dried for three days. The samples were ground into small pieces with a jaw crusher before being ground into powder with a ball mill machine (Liu et al., 2020; Öksüzoğlu & Uçurum, 2016). Every site's sample was thoroughly mixed to homogenize it and sieved to produce a powder with particle sizes less than 75µm (Thipse et al., 2002). To have both uncalcined and calcined samples for examination, some of the powdered sample’s KL, AR, MN, and DM were placed in the muffle furnace for calcination. 2.4.1 Calcination of Rock Samples Approximately 20 g of sun-dried powdered rock samples KL, AR, MN and DM were introduced into a muffle furnace found at the College of Earth Sciences, the University of Dodoma. The samples were heated for four hours at 750 o C at a rate of 10 o C per minute. The decomposition reaction of magnesite is expressed as follows: MgCO 3 (s) → MgO(s) + CO 2 (g) (1) 2.5 Sample Analysis and Characterization 2.5.1 XRF Analysis Using a Rigaku NEX CG XRF Spectrometer from the Geological Survey of Tanzania (GST), samples' elemental content was examined. The samples were crushed and processed into a very fine powder with particle size less than 75µm (Garbe-Schönberg & Müller, 2014). 15 g of powdered samples were pressed into a pellets without binder. The samples were then scanned with XRF mounted with a large-area high-throughput silicon drift detector (SDD). 2.5.2 XRD analysis The rock samples KL, AR, MN and DM, were characterized using powder X-ray diffraction (PXRD) using Burker AXS and Rigaku MiniFlex(Tiwow et al., 2018; Wang et al., 2022). The tube generates Cu-Kα (γ = 1.5406 A°) radiation at 40kV and 15 mA (Brundavanam et al., 2013; Lin et al., 2018; Pejchal et al., 2019). Diffraction patterns of samples were recorded over a range of 2θ 5–65 o for Burker AXS and 2θ 5–80 o for Rigaku MiniFlex, with scan width of 0.02 o , and scan speed/duration of 4 o /min (Almehmadi et al., 2020; Tiwow et al., 2018). Both qualitative and quantitative analysis was done using whole powder patterns fitting (WPPF) and reference intensity ratio (RIR). The method was used for analysis based on lattice constants and the crystal structure system, where a thorough profile fitting was carried out over a relatively wide angular range. The entire diffraction patterns obtained from the sample was fitted to a standard pattern generated from a proposed crystal system. The International Center for Diffraction Data (ICDD) card and PDXL2 software were used in the search and match method for the qualitative analysis (Tiwow et al., 2018). By using the RIR (Reference Intensity Ratio) approach, quantitative examination of the weight percent (wt%) of the crystalline phase was evaluated. The XRD measurements were compared with those of XRF. 3. Results and Discussion 3.1 Samples processing Despite having a similar look while uncalcined, the rock samples from varied sites revealed a range of hues after calcination. For instance, the rock sample from Chambogo (KL) took on a reddish-white hue, the one from Muriatata (AR) a broken-white hue, and the ones from Lobolosoiti (MN) and Chikaza (DM) a milk-white hue. Color variations in these samples are a sign of their varied mineralogical composition (Lantes-Suárez et al., 2015). The samples' varying colors are an indication of their diverse mineralogical and elemental composition, and formation process. 3.2 XRF results for samples KL, AR, MN and DM According to the X-ray fluorescence (XRF) results displayed in Table 1, the rock samples that were mined at Chambogo hill (KL), Muriatata hill (AR), Lobolosoiti hill (MN), and Chikaza hill (DM) had a substantial amount of magnesium oxide, and therefore high amount of magnesite from which it is formed after pyrolysis process. However, sample KL had 45.21% of MgO came in second behind the sample AR which had 46.06% of MgO. The samples MN and DM each had 43.21% of MgO. The sample AR mined at Muriatata hill in Arusha region, Tanzania had purity comparable with that mined at Liaoning Province, China (Tian et al., 2014). According to Tian et al. (2014), X-ray fluorescence results showed that the magnesite in Liaoning Province, contained 47.1% MgO. The samples KL, AR, MN, and DM had loss on ignition (LOI) values of 49.09%, 48.79%, 48.93%, and 50.08%, respectively. The loss on ignition, was mostly caused by the release of carbon dioxide from organic carbon and mineral carbonates, as well as water loss from hydrated minerals and moisture. Besides, all samples were found to contain silica (SiO 2 ), iron (III) oxide (Fe 2 O 3 ), aluminum oxide (Al 2 O 3 ), and calcium oxide (CaO) as impurities. All samples had relatively high amount of silica, but sample DM had highest (3.38%). Sample MN shown the highest percentage of calcium oxide (5.12%), whereas sample KL had the highest content of Fe 2 O 3 (1.06%). However, all samples had relatively low aluminum oxide (Al 2 O 3 ) content. Efe et al. (2020) and Kelemen et al. (2011) reported silicium, iron, and calcium carbonate as impurities of magnesite soil/rock. Moreover, research by Efe et al. (2020) found that calcium carbonate impurities have an impact on the economic value and quality of magnesite when utilized to make refractory materials and fertilizers. However, when recovering struvite from waste water or human urine using magnesite, iron impurities are more of a concern than calcium impurities. In fact, iron is needed by the plant in small amount, but the excess iron in fertilizers can contaminate ground water, cause soil acidification, and toxicity to plant roots in some specific plants. In waste water, calcium reacts to form calcium phosphate (apatite), an important plant nutrient. Because calcium readily forms apatite in waste water, it suppresses magnesite's capacity to recover struvite from sanitary waste water since it depletes waste water's phosphate content. Lu et al. (2019) reported the formation of hydroxyapatite and the incorporation of calcium ions in struvite crystals while synthesizing struvite from industrial magnesite, ammonium, and phosphate. The high concentration of CaO in magnesite also limits its use in the production of refractory materials, as CaO is hygroscopic in nature, meaning it absorbs water. In this sense, the presence of large amount of calcium impurities affects the quality of magnesite when it is used in production of refractory materials as well as struvite. In this study however, concentration of calcium oxide is too low to be considered in any sample, with the exception of the sample (MN) from Lobolosoiti which had high concentration of CaO. The XRF data indicate that, despite the high impurity levels, magnesite can still be mined from these locations for industrial applications such as manufacturing of cement, ceramics, refractory materials, struvite, and other industrial materials. However, due to CaO's propensity to absorb water, samples from Lobosoiti with a high CaO level won't be suitable for the manufacturing of refractory materials (Efe et al., 2020). Table 1 XRF results for mineralogical composition in % of magnesite KL AR MN DM L.O.I (%) 49.08 48.79 48.93 50.08 MgO (%) 45.2 46.06 43.21 43.21 SiO 2 (%) 1.15 2.24 1.17 3.38 Fe 2 O 3 (%) 1.06 0.18 0.15 0.11 Al 2 O 3 (%) 0.09 0.13 0.1 0.8 CaO (%) 0.44 0.49 5.12 1.14 As demonstrated in Table 2, all samples contain trace and minor elements as impurities. High levels of chromium (589 ppm) and nickel (385.3 ppm) were present in sample KL. Sulphur concentrations were found to be 280.7 ppm and 278.3 ppm in samples AR and MN, respectively. Sample DM had 1447.3 ppm nickel, 1062.3 ppm chromium, 1062.0 ppm vanadium and 388.3 ppm sulfur, and 384 ppm manganese. Because of the high levels of chromium in sample KL and DM samples, care should be taken when using them for fertilizer production and struvite recovery. High level of nickel and vanadium in sample DM is also of a concern. In addition, chromium has been identified as one of the heavy metal contaminants in mineral fertilizers that has detrimental impacts on the environment (Gantenbein & Khadka, 2009; Ronteltap et al., 2007). Ronteltap et al. (2007) showed that heavy metals like cadmium (Cd), chromium (Cr), iron (Fe), arsenic (As) and lead (Pb) can precipitate in stored urine and can, therefore, lead to contamination of struvite fertilizer. Moreover, Gantenbein and Khadka (2009) included arsenic, chromium, lead, mercury, nickel and vanadium as heavy metals of concern in the fertilizers in addition to cadmium. The worse scenario of cadmium incorporation into the struvite fertilizers was observed in Nepalese magnesite; where all the cadmium ends up in the struvite, leading to 1.6 mg Cd·kg -1 P in the formed struvite but below the many regulatory limits (Krähenbühl et al., 2016). However, because none of the samples had any cadmium, mercury, or lead, the magnesite soil and rock from these locations are appropriate for struvite recovery and fertilizers production. These samples' varying mineral and elemental compositions reveal variation in the process of forming magnesite deposits (Dupuis & Beaudoin, 2011; Pohl, 1989). Because diverse variables influence the formation of magnesite deposits, magnesite from different locations will have a distinct geochemical composition that will affect its economic value. Table 2 XRF results for elemental composition in ppm of magnesite KL AR MN DM Mn 77.7 ± 0.89 37.0 ± 0.56 31.3 ± 0.38 384.3 ± 2.43 Cr 589.0 ± 1.00 60.3 ± 0.54 55.0 ± 0.72 1062.3 ± 0.90 V 38.3 ± 0.50 27.7 ± 0.67 15.3 ± 0.33 1062.0 ± 0.57 K 130.3 ± 0.84 145.0 ± 0.98 223.0 ± 0.17 333.3 ± 0.96 S 75.3 ± 0.77 280.7 ± 0.62 278.3 ± 0.83 388.3 ± 0.39 Ti 81.7 ± 1.45 43.7 ± 0.88 32.7 ± 1.36 199.3 ± 0.45 Ni 385.3 ± 0.33 7.3 ± 0.33 33.0 ± 0.58 1447.3 ± 0.59 Co 10.0 ± 0.58 34.7 ± 0.33 3.3 ± 1.36 352.7 ± 1.45 Zn 9.3 ± 0.67 ND 5.3 ± 0.33 61.3 ± 0.66 Cu 35.3 ± 0.66 ND 74.3 ± 0.33 59.3 ± 0.88 Zr 1.7 ± 0.53 1.3 ± 0.88 ND 1.3 ± 0.66 Sr 12.7 ± 0.85 18.3 ± 0.33 53.3 ± 0.86 4.3 ± 0.63 Sc 12.3 ± 1.12 5.0 ± 0.58 96.0 ± 0.78 5.3 ± 0.67 4.3 Results of XRD analysis Mineralogical investigations of samples KL, AR, MN, and DM using powder X-ray diffraction revealed that magnesite was a dominant mineral phase in the rock samples (Fig. 2). The AR and DM samples each had roughly 68% magnesite, although the AR and MN samples contained 65.28% and 63.87% magnesite, respectively. Besides magnesite, the sample KL has amesite (17.07%), AR contains periclase (13.2%), MN contains calcite (15.67%), and DM contains alite (8.3%) as the second most prevalent mineral. Along with magnesite, sample KL contained amesite, andradite, anatase, vaterite, manganite, powellite, marcasite, smithsonite, zoisite, quartz, eulytine, and siderite as minor mineral phase, while SiO 2 , braunite, uvarovite, zinc, siderite, periclase, andradite, clinochlore, calcio-olivine, benitoite, phlogopite, and grossula are present in sample AR. Moreover, sample MN contains hauerite, halite, calcite, calcio-olivine, chlorapatite, gahnite, gaspeite, nitratine, spherocobaltite, uvarovite, zoisite, phlogopite, and scapolite, whereas sample DM has zinc, agaite, albite, arsenic, zoisite, pyroxene-ideal, alite and chloritoid as minor mineral phase. The commercial value of Dm magnesite rocks can be impacted by the presence of arsenic contamination. As shown in Table 3, at least four substantial peaks for the dominant mineral phase for the sample KL, AR, MN, and DM were chosen. Major peaks were identified in sample (KL) at 2q~33.23 o , 43.59 o , 54.87 o , 55.13 o , and 71.22 o ; similarly, large peaks were identified in sample (AR) at 2q~ 33.24 o , 43.65 o , and 54.89 o , 55.07 o and 71.40 o . Sample MN showed significant peaks at 2q~ 32.84 o , 43.23 o , and 54.89 o , 55.07 o and 71.40 o , whereas sample DM had major peaks at 2q~ 33.03 o , 43.38 o , and 54.53 o , 54.70 o and 70.91 o . The findings of this study are in agreement with those reported by Tian et al. (2014). All these peaks indicate the presence of well-formed crystalline magnesite (MgCO 3 ). Table 3 Major peaks, normal intensity and indices for calcined samples using Rigaku MiniFlex XRD KL AR MN DM Peaks (2θ o ) Intensity (%) h l k Peaks (2θ o ) Intensity (%) h l k Peaks (2θ o ) Intensity (%) h l k Peaks (2θ o ) Intensity (%) h l k 33.234 100 1 0 4 33.237 100 1 0 4 32.843 100 1 0 4 33.031 100 1 0 4 43.585 53.11 1 1 3 43.653 53.14 1 1 3 43.230 52.82 1 1 3 43.379 52.9 1 1 3 54.867 25.21 1 1 6 54.889 25.44 1 1 6 54.232 25.34 1 1 6 54.531 24.97 1 1 6 55.126 18.4 0 1 8 55.065 18.39 0 1 8 54.269 18.78 0 1 8 54.702 18.33 0 1 8 71.222 14.98 3 0 0 71.399 14.84 3 0 0 70.737 14.82 3 0 0 70.911 14.58 3 0 0 MgCO 3 peaks in calcined KL, AR, MN, and DM samples vanished and were replaced by MgO peaks. MgO peaks in calcined samples were seen at around 2θ of 36.9 o , 42.9 o and 62.3 o for KL, AR, MN and DM with the most significant one identified at 2θ of 42.9 o and 62.3 o (Table 3 and Fig. 3), indicating the formation of crystalline magnesium oxide (MgO) (Tian et al., 2014). For example, uncalcined sample KL had a major peak (100% intensity) at 2θ 33.2346 which disappeared upon calcination, and the second major peak at 2θ 43.5858 which shifted to 2θ 42.9507; while the calcined KL sample had major peak (100% intensity) at 2θ 42.9507 and second major peak at 62.3188 which was not present in its raw sample, showing phase transition. Furthermore, the emergence of a peaks at 2θ 36.9789 in calcined KL sample suggests a phase shift from magnesite (MgCO 3 ) to magnesia (MgO). The same thing happened in samples AR, MN, and DM; however, peak positions in DM sample were little bit different. In raw DM sample, peaks were observed at 2θ 33.0311 o , 43.3793 o , 54.531 o , and 54.7024 o , but in the calcined one at 2θ 37.0395 o , 43.051 o and 62.3996 o . Powder XRD results showed that magnesite had hexagonal crystalline structure, whereas MgO showed trigonal crystalline structure. The geochemical composition and mineral phases of the magnesite rock were confirmed by XRD measurements. Regarding the main mineral phases and contaminants, the XRD data were in agreement with that of XRF. The results demonstrated that the predominant mineral phases in both raw and calcined rock samples were consistently MgCO 3 and MgO. 4. Conclusion The aim of this study was to examine the quality and geochemical composition of magnesite rocks mined from Chambogo, Muriatata, Lobolosoiti and Chikaza for their suitability for struvite recovery from waste water and other industrial application. Samples from these sites were found to contain enough magnesite for commercial mining. XRD measurements showed that samples AR and DM had the highest percentage of magnesite, with each sample containing 68% of MgCO 3 . However, sample AR showed the highest content of magnesia (46.09% MgO), followed by sample KL with 45.2% MgO, but sample KL had relatively low impurities. Sample KL is the best of the four for the production of refractory material because it has a high concentration of MgO and a very low concentration of CaO. However, its high iron and chromium concentration makes it relatively unsuitable for for struvite recovery and fertilizer manufacturing. Sample AR, on the other hand, with the highest MgO concentration and the lowest iron and chromium concentration, is ideal for the production of both refractory materials, struvite and fertilizers. Such a high-quality magnesite ore is potential for exportation. Despite having a high proportion of magnesite, sample DM is not suitable for the production of refractory materials and fertilizers due to its low concentration of MgO and large concentrations of calcium oxide, silica and chromium. Furthermore, the presence of arsenic in the sample DM narrow down its application. 5. Declarations Conflict of interests : The authors have no relevant financial or non-financial interests to disclose. 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Chemosphere 226: 307-315. https://doi.org/10.1016/j.chemosphere.2019.03.106 Zwaan JH, Seifert AV, Vrána S, Laurs BM, Anckar B, Simmons WBS, et al. (2005) Emeralds from the Kafubu Area, Zambia. Gems & Gemology 41(2):116-148. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 23 Jul, 2024 Read the published version in Carbonates and Evaporites → Version 1 posted Editorial decision: Revision requested 08 May, 2024 Reviews received at journal 06 May, 2024 Reviewers agreed at journal 22 Apr, 2024 Reviewers agreed at journal 22 Apr, 2024 Reviews received at journal 20 Apr, 2024 Reviewers agreed at journal 19 Apr, 2024 Reviewers invited by journal 07 Apr, 2024 Editor assigned by journal 07 Apr, 2024 Submission checks completed at journal 05 Apr, 2024 First submitted to journal 19 Mar, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4128932","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":289400892,"identity":"60afde4d-d30b-4521-8c9b-56a4fbe07330","order_by":0,"name":"Daniel Tsingay Illakwahhi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2UlEQVRIiWNgGAWjYBACNnbmBsYGBoYEA2bmA0C+hAxhLcyMMC1sCSAtPIStgWth4DEA8Qlr4WNmbPw4s80uz5yd5/OrGzUWPAzsh49uIOCwZsmNbcnFls2826xzjgEdxpOWdoOQXyQfbmNO3HCYd5txDhtQiwSPGSEtzT8fbqsHauF5ZpzzjzgtbZIbtx0GaWF+nNtGpBbLmf+OA7WwmTHn9knwsBHyi3x78+GbPWeqEzecP/z4c863Ojl+9sPH8GpBsVECTBKrHASYP5CiehSMglEwCkYOAAAQ+EYTB5Tm+gAAAABJRU5ErkJggg==","orcid":"","institution":"The University of Dodoma","correspondingAuthor":true,"prefix":"","firstName":"Daniel","middleName":"Tsingay","lastName":"Illakwahhi","suffix":""},{"id":289400893,"identity":"af9cbef2-4e7b-4521-a2e9-c7d2d69c9a19","order_by":1,"name":"Maheswara Rao Vegi","email":"","orcid":"","institution":"The University of Dodoma","correspondingAuthor":false,"prefix":"","firstName":"Maheswara","middleName":"Rao","lastName":"Vegi","suffix":""},{"id":289400894,"identity":"0dc87ac1-6265-4dd4-ae15-ea246ec46743","order_by":2,"name":"Bajarang Bali Lal Srivastava","email":"","orcid":"","institution":"The University of Dodoma","correspondingAuthor":false,"prefix":"","firstName":"Bajarang","middleName":"Bali Lal","lastName":"Srivastava","suffix":""}],"badges":[],"createdAt":"2024-03-19 09:16:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4128932/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4128932/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s13146-024-00989-8","type":"published","date":"2024-07-23T16:15:58+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":54449729,"identity":"789ebeaa-6158-4916-8464-107d4c0b5136","added_by":"auto","created_at":"2024-04-10 17:40:04","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":86582,"visible":true,"origin":"","legend":"\u003cp\u003eThe map of Tanzania showing regions and sample collection sites\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4128932/v1/9d67ee54bf3ca3b79112b802.png"},{"id":54449731,"identity":"313404c9-6d1f-4131-8737-eb7e95b2bdc8","added_by":"auto","created_at":"2024-04-10 17:40:04","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":401134,"visible":true,"origin":"","legend":"\u003cp\u003eXRD Determined mineralogical composition of sample KL, AR, MN and DM using Rigaku MiniFlex XRD\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4128932/v1/4d99e7f5d6f26b13ae66d720.jpg"},{"id":54449730,"identity":"8f341303-9cfa-427f-978d-1bdc4364cb32","added_by":"auto","created_at":"2024-04-10 17:40:04","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":33250,"visible":true,"origin":"","legend":"\u003cp\u003eX-ray diffractograms for uncalcined (uncal) and calcined (cal) magnesite samples KL, AR, MN and DM using Burker AXS XRD\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4128932/v1/068d68cb59c3793238245b7b.jpg"},{"id":61596387,"identity":"597daa7d-30d6-4f41-8c10-6d557362850f","added_by":"auto","created_at":"2024-08-01 17:27:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1058537,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4128932/v1/845d4bdc-579f-4c7e-b9cf-efc91c35eccc.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Assessment of Tanzania Magnesite’s Suitability for the Struvite Recovery and Other Industrial Applications","fulltext":[{"header":"1.\tIntroduction","content":"\u003cp\u003eMagnesite is a carbonate mineral with a general formula of MgCO\u003csub\u003e3\u003c/sub\u003e. It is considered as a member of the calcite group of carbonate minerals that is a principal source of magnesium (Beyecha, 2016); Shand (2006). The mineral has the same crystal structure as calcite, a calcium carbonate with a hardness and texture similar to white magnesite and marble (Chen \u0026amp; Tao, 2004; Misch, 2012; Pluch, 2018; Siegesmund \u0026amp; T\u0026ouml;r\u0026ouml;k, 2010). In its natural state, magnesite exists as a white, gray, or brown porous crystal (Chauke, 2020; Shand, 2006). Magnesite\u0026apos;s physical appearance ranges from translucent to opaque, with variable amounts of carbonates and oxides of iron, calcium, manganese, and aluminum silicates giving it a milky-white appearance (Chauke, 2020). However, the majority of its reserves in Tanzania from which the samples used in this study are taken are milky-white deposits.\u003c/p\u003e\n\u003cp\u003eMagnesite is formed through carbonation of magnesium-rich rocks such as peridotite or serpentine during regional contact, or hydrothermal metamorphism, particularly when exposed to carbon dioxide-rich water (Efe et al., 2020; Pilchin, 2011). Magnesite formed in this manner is sometimes cryptocrystalline and contains a significant amount of chert. Since olivine is the most dominant mineral in peridotite, it is olivine which is carbonated (Grozeva et al., 2017; H\u0026ouml;velmann et al., 2012; Kelemen et al., 2011; Sissmann et al., 2014). It can also form as a result of the alteration of limestone, dolomite, marble, or any other carbonate-rich rock by magnesium-rich solutions during regional contact, or hydrothermal metamorphism (Meng et al., 2019; Rajendran et al., 2013). It might be formed in the regolith above weathering ultramafic rocks and other magnesium-rich rocks (Kelemen et al., 2011). Carbonic acid in subsurface waters promotes this formation, which frequently results in nodular magnesite. This geological process may result in to the formation of magnesite of high purity. Magnesite could even form as a secondary mineral as a result of precipitation in veins and fractures that cut through carbonate and ultramafic rocks (Azer et al., 2019; Chauke, 2020). Moreover, magnesite is often silicified or mixed with chert, marking it deceptive hard. It produces effervescence when treated with HCl, which is used as a litmus test; however, the presence of chert reduces the apparent effervescence with HCl.\u003c/p\u003e\n\u003cp\u003eMagnesite can be found in many different places and countries around the world. Currently, the largest producer of magnesite as well as the country with the most deposits is China (Drnek et al., 2018; Efe et al., 2020). According to USGS, Russia, USA, Australia, Austria, Greece, Spain, Slovakia, Brazil, and Turkey are other nations with sizable magnesite reserves beside China (Merrill, 2022). Nevertheless, Russian reserves make up the majority. In addition, Tanzania is home to numerous magnesite deposits found in different regions. According to the Geological Survey of Tanzania (GST) (2018), there are currently twelve locations with known magnesite deposits located in six regions. The magnesite deposit at Chambogo in Same district, Kilimanjaro region, is currently being mined for commercial purposes, while the excavation process at Muriatata had just begun. \u003c/p\u003e\n\u003cp\u003eMagnesite on heating produces magnesia (MgO), the chemical used to make high heat resistant bricks used to line kilns, industrial ovens, incinerators and blast furnaces (An et al., 2018; Efe et al., 2020). It is widely used in many industrial areas such as iron-steel, limestone, cement, glass, paper, fuel, printing inks, pharmaceuticals, and stock farming (Abali et al., 2006; Efe et al., 2020; Gulluce et al., 2020; Woodall et al., 2019). Besides, it is used to produce magnesium-based chemicals, fertilizers (Kiani et al., 2019; Kr\u0026auml;henb\u0026uuml;hl et al., 2016) and can even be refined into magnesium metal (La\u0026ccedil;in et al., 2005). According to reports (Kr\u0026auml;henb\u0026uuml;hl et al., 2016; X. Li et al., 2021; Zhang et al., 2019), magnesite can also be utilized to recover struvite from waste water. Furthermore, magnesite is commonly used in the production of tumbled stones, beads, and cabochons. White magnesite is a porous mineral; it can therefore be cut and dyed to produce almost any color (Fritsch et al., 2019; Manutchehr-Danai, 2005; Zwaan et al., 2005). However, in Tanzania, magnesia is mined for use primarily in the ceramic, cement, fertilizer, and glass industries.\u003c/p\u003e\n\u003cp\u003eThe grade of magnesite rock deposits is affected by magnesium content, impurity types, grain size, crystal structures, formation conditions, porosity, and other mineralogical composition (Alhaddad et al., 2022; Kr\u0026auml;henb\u0026uuml;hl et al., 2016; Pudlo et al., 2012). However, the magnesium amount, impurity levels and types are the most important criteria in determining the grade of magnesite rock. Magnesite has been found to contain impurities such as silicium, iron, and calcium carbonate (Efe et al., 2020; Kelemen et al., 2011). Due to its ability to absorb moisture from the air, magnesite\u0026rsquo;s calcium carbonate content affects the quality of refractory materials. For example, a study by Efe et al. (2020) reported the impact of calcium carbonate impurities on the quality and economic value of magnesite when used in the production of refractory materials. Elevated levels of heavy metal impurities such as chromium, lead, iron, cadmium, and radioactive elements such as arsenic and uranium might impair magnesite\u0026apos;s capacity to be used for struvite recovery and fertilizer production. Moreover, lead, cadmium, iron, arsenic, and uranium have been identified as potentially harmful contaminants in struvite, liming materials, micronutrient fertilizers, and phosphate-based fertilizers (Gon\u0026ccedil;alves Jr et al., 2014; Gupta et al., 2014; Taylor et al., 2016).\u003c/p\u003e\n\u003cp\u003eDespite the fact that Tanzania has numerous proven magnesite deposits, critical information on quality and geochemical composition is absent due to limited studies. The quality of magnesite deposits can vary significantly from one location to another (Li et al., 2014; Masindi et al., 2016), depending on the geological environments and the dominant minerals in the parent rock (Hojamberdiev et al., 2010; Pohl, 1989). Nevertheless, it is worth noting that this information is important for agricultural and industrial stakeholders. This study however, tries to examine the quality and mineralogical composition of magnesite deposits found in Tanzania.\u003c/p\u003e"},{"header":"2. Methodology","content":"\u003cp\u003e\u003cstrong\u003e2.1 Study Sites\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMagnesite rocks for this study were mined and collected from four sites found in four regions of Tanzania (Fig. 1). These sites are Chambogo magnesite hill (4\u0026deg;8\u0026apos;7.801\u0026quot; South, 37\u0026deg;48\u0026apos;43.583\u0026quot; East) located in Same district, Kilimanjaro region, Muriatata hill (2\u0026deg;43\u0026apos;49.480\u0026quot; South, 36\u0026deg;29\u0026apos;36.641\u0026quot; East) located in Longido district, Arusha region, Lobolosoiti hill (4\u0026deg;22\u0026apos;28.450\u0026quot; South, 37\u0026deg;28\u0026apos;10.542\u0026quot; East) located in Simanjiro district, Manyara region and Chikaza hill (6\u0026deg;13\u0026apos;39.027\u0026quot; South, 35\u0026deg;58\u0026apos;1.025\u0026quot; East) located in Dodoma Municipal, Dodoma region.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2 Sampling Procedure\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAccording to Geological Survey of Tanzania (GST), there are twelve magnesite rock/soil deposits found in six regions of Tanzania. To select four regions from which samples were taken, a simple random sampling method was used (Noor et al., 2022; West, 2016). A simple random sampling method was used as well to select a site in regions with more than one location. The procedure entailed writing regions or site names on pieces of paper, placing them in a box, and selecting one name at random. For example, the Dodoma region had four locations, the Arusha region had two, and the Kilimanjaro and Manyara regions each had one. For the samples to be representative, the sites were divided into four quadrat within 50 meter diameter.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3 Sample Collection\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe texture, colors, and effervescence of the rock samples with hydrochloric acid were used as a litmus test for preliminary magnesite identification (You et al., 2015). It should be noted that all metals carbonates react with hydrochloric acid form effervescence. At least 5 kg of rock/soil was extracted at each quadrat along the cardinal directions within 50 meters perimeter; making a total of 20 kg of sample per site. Rock samples from Chambogo, Muriatata, Lobolosoiti and Chikaza were labeled as KL, AR, MN and DM respectively. The samples were then transported to the University of Dodoma for preparation and analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.4 Samples Preparation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe rock samples were thoroughly washed to remove dust and other earthly materials and then sun dried for three days. The samples were ground into small pieces with a jaw crusher before being ground into powder with a ball mill machine (Liu et al., 2020; \u0026Ouml;ks\u0026uuml;zoğlu \u0026amp; U\u0026ccedil;urum, 2016). Every site\u0026apos;s sample was thoroughly mixed to homogenize it and sieved to produce a powder with particle sizes less than 75\u0026micro;m (Thipse et al., 2002). To have both uncalcined and calcined samples for examination, some of the powdered sample\u0026rsquo;s KL, AR, MN, and DM were placed in the muffle furnace for calcination.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.4.1 Calcination of Rock Samples\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eApproximately 20 g of sun-dried powdered rock samples KL, AR, MN and DM were introduced into a muffle furnace found at the College of Earth Sciences, the University of Dodoma. The samples were heated for four hours at 750\u003csup\u003eo\u003c/sup\u003eC at a rate of 10\u003csup\u003eo\u003c/sup\u003eC per minute. The decomposition reaction of magnesite is expressed as follows:\u003c/p\u003e\n\u003cp\u003eMgCO\u003csub\u003e3\u003c/sub\u003e(s) \u0026rarr; MgO(s) + CO\u003csub\u003e2\u003c/sub\u003e(g)\u0026nbsp; \u0026nbsp; \u0026nbsp; (1)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.5 Sample Analysis and Characterization\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.5.1 XRF Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eUsing a Rigaku NEX CG XRF Spectrometer from the Geological Survey of Tanzania (GST), samples\u0026apos; elemental content was examined. The samples were crushed and processed into a very fine powder with particle size less than 75\u0026micro;m (Garbe-Sch\u0026ouml;nberg \u0026amp; M\u0026uuml;ller, 2014). 15 g of powdered samples were pressed into a pellets without binder. The samples were then scanned with XRF mounted with a large-area high-throughput silicon drift detector (SDD).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.5.2 XRD analysis\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe rock samples KL, AR, MN and DM, were characterized using powder X-ray diffraction (PXRD) using Burker AXS and Rigaku MiniFlex(Tiwow et al., 2018; Wang et al., 2022). The tube generates Cu-K\u0026alpha; (\u0026gamma; = 1.5406 A\u0026deg;) radiation at 40kV and 15 mA (Brundavanam et al., 2013; Lin et al., 2018; Pejchal et al., 2019). Diffraction patterns of samples were recorded over a range of 2\u0026theta; 5\u0026ndash;65\u003csup\u003eo\u003c/sup\u003e for Burker AXS and 2\u0026theta; 5\u0026ndash;80\u003csup\u003eo\u003c/sup\u003e for Rigaku MiniFlex, with scan width of 0.02\u003csup\u003eo\u003c/sup\u003e, and scan speed/duration of 4\u003csup\u003eo\u003c/sup\u003e /min (Almehmadi et al., 2020; Tiwow et al., 2018). Both qualitative and quantitative analysis was done using whole powder patterns fitting (WPPF) and reference intensity ratio (RIR). The method was used for analysis based on lattice constants and the crystal structure system, where a thorough profile fitting was carried out over a relatively wide angular range. The entire diffraction patterns obtained from the sample was fitted to a standard pattern generated from a proposed crystal system. The International Center for Diffraction Data (ICDD) card and PDXL2 software were used in the search and match method for the qualitative analysis (Tiwow et al., 2018). By using the RIR (Reference Intensity Ratio) approach, quantitative examination of the weight percent (wt%) of the crystalline phase was evaluated. The XRD measurements were compared with those of XRF.\u003c/p\u003e"},{"header":"3. Results and Discussion","content":"\u003cp\u003e\u003cstrong\u003e3.1 Samples processing\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDespite having a similar look while uncalcined, the rock samples from varied sites revealed a range of hues after calcination. For instance, the rock sample from Chambogo (KL) took on a reddish-white hue, the one from Muriatata (AR) a broken-white hue, and the ones from Lobolosoiti (MN) and Chikaza (DM) a milk-white hue. Color variations in these samples are a sign of their varied mineralogical composition (Lantes-Su\u0026aacute;rez et al., 2015). The samples' varying colors are an indication of their diverse mineralogical and elemental composition, and formation process.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2 XRF results for samples KL, AR, MN and DM\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAccording to the X-ray fluorescence (XRF) results displayed in Table 1, the rock samples that were mined at Chambogo hill (KL), Muriatata hill (AR), Lobolosoiti hill (MN), and Chikaza hill (DM) had a substantial amount of magnesium oxide, and therefore high amount of magnesite from which it is formed after pyrolysis process. However, sample KL had 45.21% of MgO came in second behind the sample AR which had 46.06% of MgO. The samples MN and DM each had 43.21% of MgO. The sample AR mined at Muriatata hill in Arusha region, Tanzania had purity comparable with that mined at Liaoning Province, China (Tian et al., 2014). According to Tian et al. (2014), X-ray fluorescence results showed that the magnesite in Liaoning Province, contained 47.1% MgO.\u003c/p\u003e\n\u003cp\u003eThe samples KL, AR, MN, and DM had loss on ignition (LOI) values of 49.09%, 48.79%, 48.93%, and 50.08%, respectively. The loss on ignition, was mostly caused by the release of carbon dioxide from organic carbon and mineral carbonates, as well as water loss from hydrated minerals and moisture. Besides, all samples were found to contain silica (SiO\u003csub\u003e2\u003c/sub\u003e), iron (III) oxide (Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e), aluminum oxide (Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e), and calcium oxide (CaO) as impurities. All samples had relatively high amount of silica, but sample DM had highest (3.38%). Sample MN shown the highest percentage of calcium oxide (5.12%), whereas sample KL had the highest content of Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (1.06%). However, all samples had relatively low aluminum oxide (Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e) content.\u003c/p\u003e\n\u003cp\u003eEfe et al. (2020) and Kelemen et al. (2011) reported silicium, iron, and calcium carbonate as impurities of magnesite soil/rock. Moreover, research by Efe et al. (2020) found that calcium carbonate impurities have an impact on the economic value and quality of magnesite when utilized to make refractory materials and fertilizers. However, when recovering struvite from waste water or human urine using magnesite, iron impurities are more of a concern than calcium impurities. In fact, iron is needed by the plant in small amount, but the excess iron in fertilizers can contaminate ground water, cause soil acidification, and toxicity to plant roots in some specific plants. In waste water, calcium reacts to form calcium phosphate (apatite), an important plant nutrient. Because calcium readily forms apatite in waste water, it suppresses magnesite's capacity to recover struvite from sanitary waste water since it depletes waste water's phosphate content. Lu et al. (2019) reported the formation of hydroxyapatite and the incorporation of calcium ions in struvite crystals while synthesizing struvite from industrial magnesite, ammonium, and phosphate. The high concentration of CaO in magnesite also limits its use in the production of refractory materials, as CaO is hygroscopic in nature, meaning it absorbs water. In this sense, the presence of large amount of calcium impurities affects the quality of magnesite when it is used in production of refractory materials as well as struvite. In this study however, concentration of calcium oxide is too low to be considered in any sample, with the exception of the sample (MN) from Lobolosoiti which had high concentration of CaO.\u003c/p\u003e\n\u003cp\u003eThe XRF data indicate that, despite the high impurity levels, magnesite can still be mined from these locations for industrial applications such as manufacturing of cement, ceramics, refractory materials, struvite, and other industrial materials. However, due to CaO's propensity to absorb water, samples from Lobosoiti with a high CaO level won't be suitable for the manufacturing of refractory materials (Efe et al., 2020).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1\u003c/strong\u003e XRF results for mineralogical composition in % of magnesite\u003c/p\u003e\n\u003ctable border=\"1\" width=\"395\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd valign=\"bottom\" width=\"21.515151515151516%\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd colspan=\"2\" valign=\"bottom\" width=\"20.303030303030305%\"\u003e\n\u003cp\u003eKL\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"19.393939393939394%\"\u003e\n\u003cp\u003eAR\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"19.393939393939394%\"\u003e\n\u003cp\u003eMN\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"19.393939393939394%\"\u003e\n\u003cp\u003eDM\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"26.363636363636363%\"\u003e\n\u003cp\u003eL.O.I (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" width=\"15.454545454545455%\"\u003e\n\u003cp\u003e49.08\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e48.79\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e48.93\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e50.08\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"21.515151515151516%\"\u003e\n\u003cp\u003eMgO (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" width=\"20.303030303030305%\"\u003e\n\u003cp\u003e45.2\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e46.06\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e43.21\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e43.21\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"21.515151515151516%\"\u003e\n\u003cp\u003eSiO\u003csub\u003e2\u0026nbsp;\u003c/sub\u003e(%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" width=\"20.303030303030305%\"\u003e\n\u003cp\u003e1.15\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e2.24\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e1.17\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e3.38\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"21.515151515151516%\"\u003e\n\u003cp\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e(%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" width=\"20.303030303030305%\"\u003e\n\u003cp\u003e1.06\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e0.18\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e0.15\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e0.11\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"21.515151515151516%\"\u003e\n\u003cp\u003eAl\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" width=\"20.303030303030305%\"\u003e\n\u003cp\u003e0.09\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e0.13\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e0.1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e0.8\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"21.515151515151516%\"\u003e\n\u003cp\u003eCaO (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"2\" width=\"20.303030303030305%\"\u003e\n\u003cp\u003e0.44\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e0.49\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e5.12\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"19.393939393939394%\"\u003e\n\u003cp\u003e1.14\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAs demonstrated in Table 2, all samples contain trace and minor elements as impurities. High levels of chromium (589 ppm) and nickel (385.3 ppm) were present in sample KL. Sulphur concentrations were found to be 280.7 ppm and 278.3 ppm in samples AR and MN, respectively. Sample DM had 1447.3 ppm nickel, 1062.3 ppm chromium, 1062.0 ppm vanadium and 388.3 ppm sulfur, and 384 ppm manganese. Because of the high levels of chromium in sample KL and DM samples, care should be taken when using them for fertilizer production and struvite recovery. High level of nickel and vanadium in sample DM is also of a concern. In addition, chromium has been identified as one of the heavy metal contaminants in mineral fertilizers that has detrimental impacts on the environment (Gantenbein \u0026amp; Khadka, 2009; Ronteltap et al., 2007). Ronteltap et al. (2007) showed that heavy metals like cadmium (Cd), chromium (Cr), iron (Fe), arsenic (As) and lead (Pb) can precipitate in stored urine and can, therefore, lead to contamination of struvite fertilizer. Moreover, Gantenbein and Khadka (2009) included arsenic, chromium, lead, mercury, nickel and vanadium as heavy metals of concern in the fertilizers in addition to cadmium. The worse scenario of cadmium incorporation into the struvite fertilizers was observed in Nepalese magnesite; where all the cadmium ends up in the struvite, leading to 1.6 mg Cd\u0026middot;kg\u003csup\u003e-1\u003c/sup\u003e P in the formed struvite but below the many regulatory limits (Kr\u0026auml;henb\u0026uuml;hl et al., 2016). However, because none of the samples had any cadmium, mercury, or lead, the magnesite soil and rock from these locations are appropriate for struvite recovery and fertilizers production.\u003c/p\u003e\n\u003cp\u003eThese samples' varying mineral and elemental compositions reveal variation in the process of forming magnesite deposits (Dupuis \u0026amp; Beaudoin, 2011; Pohl, 1989). Because diverse variables influence the formation of magnesite deposits, magnesite from different locations will have a distinct geochemical composition that will affect its economic value.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u003c/strong\u003e XRF results for elemental composition in ppm of magnesite\u003c/p\u003e\n\u003ctable border=\"1\" width=\"650\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd valign=\"bottom\" width=\"7.990314769975787%\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"20.82324455205811%\"\u003e\n\u003cp\u003eKL\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"23.24455205811138%\"\u003e\n\u003cp\u003eAR\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"21.791767554479417%\"\u003e\n\u003cp\u003eMN\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"26.150121065375302%\"\u003e\n\u003cp\u003eDM\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"7.990314769975787%\"\u003e\n\u003cp\u003eMn\u0026nbsp;\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"20.82324455205811%\"\u003e\n\u003cp\u003e77.7 \u0026plusmn; 0.89\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"23.24455205811138%\"\u003e\n\u003cp\u003e37.0 \u0026plusmn; 0.56\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"21.791767554479417%\"\u003e\n\u003cp\u003e31.3 \u0026plusmn; 0.38\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"26.150121065375302%\"\u003e\n\u003cp\u003e384.3 \u0026plusmn; 2.43\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"7.990314769975787%\"\u003e\n\u003cp\u003eCr\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"20.82324455205811%\"\u003e\n\u003cp\u003e589.0 \u0026plusmn; 1.00\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"23.24455205811138%\"\u003e\n\u003cp\u003e60.3 \u0026plusmn; 0.54\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"21.791767554479417%\"\u003e\n\u003cp\u003e55.0 \u0026plusmn; 0.72\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"26.150121065375302%\"\u003e\n\u003cp\u003e1062.3 \u0026plusmn; 0.90\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"7.990314769975787%\"\u003e\n\u003cp\u003eV\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"20.82324455205811%\"\u003e\n\u003cp\u003e38.3 \u0026plusmn; 0.50\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"23.24455205811138%\"\u003e\n\u003cp\u003e27.7 \u0026plusmn; 0.67\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"21.791767554479417%\"\u003e\n\u003cp\u003e15.3 \u0026plusmn; 0.33\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"26.150121065375302%\"\u003e\n\u003cp\u003e1062.0 \u0026plusmn; 0.57\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"7.990314769975787%\"\u003e\n\u003cp\u003eK\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"20.82324455205811%\"\u003e\n\u003cp\u003e130.3 \u0026plusmn; 0.84\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"23.24455205811138%\"\u003e\n\u003cp\u003e145.0 \u0026plusmn; 0.98\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"21.791767554479417%\"\u003e\n\u003cp\u003e223.0 \u0026plusmn; 0.17\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"26.150121065375302%\"\u003e\n\u003cp\u003e333.3 \u0026plusmn; 0.96\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"7.990314769975787%\"\u003e\n\u003cp\u003eS\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"20.82324455205811%\"\u003e\n\u003cp\u003e75.3 \u0026plusmn; 0.77\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"23.24455205811138%\"\u003e\n\u003cp\u003e280.7 \u0026plusmn; 0.62\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"21.791767554479417%\"\u003e\n\u003cp\u003e278.3 \u0026plusmn; 0.83\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"26.150121065375302%\"\u003e\n\u003cp\u003e388.3 \u0026plusmn; 0.39\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"7.990314769975787%\"\u003e\n\u003cp\u003eTi\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"20.82324455205811%\"\u003e\n\u003cp\u003e81.7 \u0026plusmn; 1.45\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"23.24455205811138%\"\u003e\n\u003cp\u003e43.7 \u0026plusmn; 0.88\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"21.791767554479417%\"\u003e\n\u003cp\u003e32.7 \u0026plusmn; 1.36\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"26.150121065375302%\"\u003e\n\u003cp\u003e199.3 \u0026plusmn; 0.45\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"7.990314769975787%\"\u003e\n\u003cp\u003eNi\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"20.82324455205811%\"\u003e\n\u003cp\u003e385.3 \u0026plusmn; 0.33\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"23.24455205811138%\"\u003e\n\u003cp\u003e7.3 \u0026plusmn; 0.33\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"21.791767554479417%\"\u003e\n\u003cp\u003e33.0 \u0026plusmn; 0.58\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"26.150121065375302%\"\u003e\n\u003cp\u003e1447.3 \u0026plusmn; 0.59\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"7.990314769975787%\"\u003e\n\u003cp\u003eCo\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"20.82324455205811%\"\u003e\n\u003cp\u003e10.0 \u0026plusmn; 0.58\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"23.24455205811138%\"\u003e\n\u003cp\u003e34.7 \u0026plusmn; 0.33\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"21.791767554479417%\"\u003e\n\u003cp\u003e3.3 \u0026plusmn; 1.36\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"26.150121065375302%\"\u003e\n\u003cp\u003e352.7 \u0026plusmn; 1.45\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"7.990314769975787%\"\u003e\n\u003cp\u003eZn\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"20.82324455205811%\"\u003e\n\u003cp\u003e9.3 \u0026plusmn; 0.67\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"23.24455205811138%\"\u003e\n\u003cp\u003eND\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"21.791767554479417%\"\u003e\n\u003cp\u003e5.3 \u0026plusmn; 0.33\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"26.150121065375302%\"\u003e\n\u003cp\u003e61.3 \u0026plusmn; 0.66\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"7.990314769975787%\"\u003e\n\u003cp\u003eCu\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"20.82324455205811%\"\u003e\n\u003cp\u003e35.3 \u0026plusmn; 0.66\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"23.24455205811138%\"\u003e\n\u003cp\u003eND\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"21.791767554479417%\"\u003e\n\u003cp\u003e74.3 \u0026plusmn; 0.33\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"26.150121065375302%\"\u003e\n\u003cp\u003e59.3 \u0026plusmn; 0.88\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"7.990314769975787%\"\u003e\n\u003cp\u003eZr\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"20.82324455205811%\"\u003e\n\u003cp\u003e1.7 \u0026plusmn; 0.53\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"23.24455205811138%\"\u003e\n\u003cp\u003e1.3 \u0026plusmn; 0.88\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"21.791767554479417%\"\u003e\n\u003cp\u003eND\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"26.150121065375302%\"\u003e\n\u003cp\u003e1.3 \u0026plusmn; 0.66\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"7.990314769975787%\"\u003e\n\u003cp\u003eSr\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"20.82324455205811%\"\u003e\n\u003cp\u003e12.7 \u0026plusmn; 0.85\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"23.24455205811138%\"\u003e\n\u003cp\u003e18.3 \u0026plusmn; 0.33\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"21.791767554479417%\"\u003e\n\u003cp\u003e53.3 \u0026plusmn; 0.86\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"26.150121065375302%\"\u003e\n\u003cp\u003e4.3 \u0026plusmn; 0.63\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd width=\"7.990314769975787%\"\u003e\n\u003cp\u003eSc\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"20.82324455205811%\"\u003e\n\u003cp\u003e12.3 \u0026plusmn; 1.12\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"23.24455205811138%\"\u003e\n\u003cp\u003e5.0 \u0026plusmn; 0.58\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"21.791767554479417%\"\u003e\n\u003cp\u003e96.0 \u0026plusmn; 0.78\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd width=\"26.150121065375302%\"\u003e\n\u003cp\u003e5.3 \u0026plusmn; 0.67\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e4.3 Results of XRD analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMineralogical investigations of samples KL, AR, MN, and DM using powder X-ray diffraction revealed that magnesite was a dominant mineral phase in the rock samples (Fig. 2). The AR and DM samples each had roughly 68% magnesite, although the AR and MN samples contained 65.28% and 63.87% magnesite, respectively. Besides magnesite, the sample KL has amesite (17.07%), AR contains periclase (13.2%), MN contains calcite (15.67%), and DM contains alite (8.3%) as the second most prevalent mineral.\u003c/p\u003e\n\u003cp\u003eAlong with magnesite, sample KL contained amesite, andradite, anatase, vaterite, manganite, powellite, marcasite, smithsonite, zoisite, quartz, eulytine, and siderite as minor mineral phase, while SiO\u003csub\u003e2\u003c/sub\u003e, braunite, uvarovite, zinc, siderite, periclase, andradite, clinochlore, calcio-olivine, benitoite, phlogopite, and grossula are present in sample AR. Moreover, sample MN contains hauerite, halite, calcite, calcio-olivine, chlorapatite, gahnite, gaspeite, nitratine, spherocobaltite, uvarovite, zoisite, phlogopite, and scapolite, whereas sample DM has zinc, agaite, albite, arsenic, zoisite, pyroxene-ideal, alite and chloritoid as minor mineral phase. The commercial value of Dm magnesite rocks can be impacted by the presence of arsenic contamination.\u003c/p\u003e\n\u003cp\u003eAs shown in Table 3, at least four substantial peaks for the dominant mineral phase for the sample KL, AR, MN, and DM were chosen. Major peaks were identified in sample (KL) at 2q~33.23\u003csup\u003eo\u003c/sup\u003e, 43.59\u003csup\u003eo\u003c/sup\u003e, 54.87\u003csup\u003eo\u003c/sup\u003e, 55.13\u003csup\u003eo\u003c/sup\u003e, and 71.22\u003csup\u003eo\u003c/sup\u003e; similarly, large peaks were identified in sample (AR) at 2q~ 33.24\u003csup\u003eo\u003c/sup\u003e, 43.65\u003csup\u003e\u0026nbsp;o\u003c/sup\u003e, and 54.89\u003csup\u003eo\u003c/sup\u003e, 55.07\u003csup\u003e\u0026nbsp;o\u003c/sup\u003e and 71.40\u003csup\u003e\u0026nbsp;o\u003c/sup\u003e. Sample MN showed significant peaks at 2q~ 32.84\u003csup\u003eo\u003c/sup\u003e, 43.23\u003csup\u003eo\u003c/sup\u003e, and 54.89\u003csup\u003eo\u003c/sup\u003e, 55.07\u003csup\u003e\u0026nbsp;o\u003c/sup\u003e and 71.40\u003csup\u003e\u0026nbsp;\u003c/sup\u003e\u003csup\u003eo\u003c/sup\u003e, whereas sample DM had major peaks at 2q~ 33.03\u003csup\u003eo\u003c/sup\u003e, 43.38\u003csup\u003eo\u003c/sup\u003e, and 54.53\u003csup\u003eo\u003c/sup\u003e, 54.70\u003csup\u003e\u0026nbsp;o\u003c/sup\u003e and 70.91\u003csup\u003eo\u003c/sup\u003e. The findings of this study are in agreement with those reported by Tian et al. (2014). All these peaks indicate the presence of well-formed crystalline magnesite (MgCO\u003csub\u003e3\u003c/sub\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3\u003c/strong\u003e Major peaks, normal intensity and indices for calcined samples using Rigaku MiniFlex XRD\u003c/p\u003e\n\u003ctable border=\"1\" width=\"850\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"3\" valign=\"bottom\" width=\"25.113464447806354%\"\u003e\n\u003cp\u003eKL\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"3\" valign=\"bottom\" width=\"25.113464447806354%\"\u003e\n\u003cp\u003eAR\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"3\" valign=\"bottom\" width=\"25.56732223903177%\"\u003e\n\u003cp\u003eMN\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"3\" valign=\"bottom\" width=\"24.20574886535552%\"\u003e\n\u003cp\u003eDM\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd valign=\"bottom\" width=\"9.06344410876133%\"\u003e\n\u003cp\u003ePeaks (2\u0026theta;\u003csup\u003eo\u003c/sup\u003e)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003eIntensity (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"6.7975830815709966%\"\u003e\n\u003cp\u003e\u0026nbsp;h l k\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"8.91238670694864%\"\u003e\n\u003cp\u003ePeaks\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;(2\u0026theta;\u003csup\u003eo\u003c/sup\u003e)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003eIntensity (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.099697885196375%\"\u003e\n\u003cp\u003e\u0026nbsp;h l k\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"8.761329305135952%\"\u003e\n\u003cp\u003e\u0026nbsp;Peaks (2\u0026theta;\u003csup\u003eo\u003c/sup\u003e)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003eIntensity (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.552870090634441%\"\u003e\n\u003cp\u003e\u0026nbsp;h l k\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.7039274924471295%\"\u003e\n\u003cp\u003ePeaks (2\u0026theta;\u003csup\u003eo\u003c/sup\u003e)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003eIntensity (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.2507552870090635%\"\u003e\n\u003cp\u003e\u0026nbsp;h l k\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd valign=\"bottom\" width=\"9.06344410876133%\"\u003e\n\u003cp\u003e33.234\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e100\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"6.7975830815709966%\"\u003e\n\u003cp\u003e1 0 4\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"8.91238670694864%\"\u003e\n\u003cp\u003e33.237\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e100\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.099697885196375%\"\u003e\n\u003cp\u003e1 0 4\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"8.761329305135952%\"\u003e\n\u003cp\u003e32.843\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e100\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.552870090634441%\"\u003e\n\u003cp\u003e1 0 4\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.7039274924471295%\"\u003e\n\u003cp\u003e33.031\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e100\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.2507552870090635%\"\u003e\n\u003cp\u003e1 0 4\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd valign=\"bottom\" width=\"9.06344410876133%\"\u003e\n\u003cp\u003e43.585\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e53.11\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"6.7975830815709966%\"\u003e\n\u003cp\u003e1 1 3\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"8.91238670694864%\"\u003e\n\u003cp\u003e43.653\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e53.14\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.099697885196375%\"\u003e\n\u003cp\u003e1 1 3\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"8.761329305135952%\"\u003e\n\u003cp\u003e43.230\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e52.82\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.552870090634441%\"\u003e\n\u003cp\u003e1 1 3\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.7039274924471295%\"\u003e\n\u003cp\u003e43.379\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e52.9\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.2507552870090635%\"\u003e\n\u003cp\u003e1 1 3\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd valign=\"bottom\" width=\"9.06344410876133%\"\u003e\n\u003cp\u003e54.867\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e25.21\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"6.7975830815709966%\"\u003e\n\u003cp\u003e1 1 6\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"8.91238670694864%\"\u003e\n\u003cp\u003e54.889\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e25.44\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.099697885196375%\"\u003e\n\u003cp\u003e1 1 6\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"8.761329305135952%\"\u003e\n\u003cp\u003e54.232\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e25.34\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.552870090634441%\"\u003e\n\u003cp\u003e1 1 6\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.7039274924471295%\"\u003e\n\u003cp\u003e54.531\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e24.97\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.2507552870090635%\"\u003e\n\u003cp\u003e1 1 6\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd valign=\"bottom\" width=\"9.06344410876133%\"\u003e\n\u003cp\u003e55.126\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e18.4\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"6.7975830815709966%\"\u003e\n\u003cp\u003e0 1 8\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"8.91238670694864%\"\u003e\n\u003cp\u003e55.065\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e18.39\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.099697885196375%\"\u003e\n\u003cp\u003e0 1 8\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"8.761329305135952%\"\u003e\n\u003cp\u003e54.269\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e18.78\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.552870090634441%\"\u003e\n\u003cp\u003e0 1 8\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.7039274924471295%\"\u003e\n\u003cp\u003e54.702\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e18.33\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.2507552870090635%\"\u003e\n\u003cp\u003e0 1 8\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd valign=\"bottom\" width=\"9.06344410876133%\"\u003e\n\u003cp\u003e71.222\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e14.98\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"6.7975830815709966%\"\u003e\n\u003cp\u003e3 0 0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"8.91238670694864%\"\u003e\n\u003cp\u003e71.399\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e14.84\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.099697885196375%\"\u003e\n\u003cp\u003e3 0 0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"8.761329305135952%\"\u003e\n\u003cp\u003e70.737\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e14.82\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.552870090634441%\"\u003e\n\u003cp\u003e3 0 0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.7039274924471295%\"\u003e\n\u003cp\u003e70.911\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"9.214501510574019%\"\u003e\n\u003cp\u003e14.58\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd valign=\"bottom\" width=\"7.2507552870090635%\"\u003e\n\u003cp\u003e3 0 0\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eMgCO\u003csub\u003e3\u003c/sub\u003e peaks in calcined KL, AR, MN, and DM samples vanished and were replaced by MgO peaks. MgO peaks in calcined samples were seen at around 2\u0026theta; of 36.9\u003csup\u003eo\u003c/sup\u003e, 42.9\u003csup\u003eo\u003c/sup\u003e and 62.3\u003csup\u003eo\u0026nbsp;\u003c/sup\u003efor\u003csup\u003e\u0026nbsp;\u003c/sup\u003eKL, AR, MN and DM with the most significant one identified at 2\u0026theta; of 42.9\u003csup\u003eo\u003c/sup\u003e and 62.3\u003csup\u003eo\u0026nbsp;\u003c/sup\u003e(Table 3 and Fig. 3), indicating the formation of crystalline magnesium oxide (MgO) (Tian et al., 2014).\u003c/p\u003e\n\u003cp\u003eFor example, uncalcined sample KL had a major peak (100% intensity) at 2\u0026theta; 33.2346 which disappeared upon calcination, and the second major peak at 2\u0026theta; 43.5858 which shifted to 2\u0026theta; 42.9507; while the calcined KL sample had major peak (100% intensity) at 2\u0026theta; 42.9507 and second major peak at 62.3188 which was not present in its raw sample, showing phase transition. Furthermore, the emergence of a peaks at 2\u0026theta; 36.9789 in calcined KL sample suggests a phase shift from magnesite (MgCO\u003csub\u003e3\u003c/sub\u003e) to magnesia (MgO). The same thing happened in samples AR, MN, and DM; however, peak positions in DM sample were little bit different. In raw DM sample, peaks were observed at 2\u0026theta; 33.0311\u003csup\u003eo\u003c/sup\u003e, 43.3793\u003csup\u003eo\u003c/sup\u003e, 54.531\u003csup\u003eo\u003c/sup\u003e, and 54.7024\u003csup\u003eo\u003c/sup\u003e, but in the calcined one at 2\u0026theta; 37.0395\u003csup\u003eo\u003c/sup\u003e, 43.051\u003csup\u003eo\u003c/sup\u003e and 62.3996\u003csup\u003eo\u003c/sup\u003e. Powder XRD results showed that magnesite had hexagonal crystalline structure, whereas MgO showed trigonal crystalline structure. The geochemical composition and mineral phases of the magnesite rock were confirmed by XRD measurements. Regarding the main mineral phases and contaminants, the XRD data were in agreement with that of XRF. The results demonstrated that the predominant mineral phases in both raw and calcined rock samples were consistently MgCO\u003csub\u003e3\u003c/sub\u003e and MgO.\u003c/p\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThe aim of this study was to examine the quality and geochemical composition of magnesite rocks mined from Chambogo, Muriatata, Lobolosoiti and Chikaza for their suitability for struvite recovery from waste water and other industrial application. Samples from these sites were found to contain enough magnesite for commercial mining. XRD measurements showed that samples AR and DM had the highest percentage of magnesite, with each sample containing 68% of MgCO\u003csub\u003e3\u003c/sub\u003e. However, sample AR showed the highest content of magnesia (46.09% MgO), followed by sample KL with 45.2% MgO, but sample KL had relatively low impurities. Sample KL is the best of the four for the production of refractory material because it has a high concentration of MgO and a very low concentration of CaO. However, its high iron and chromium concentration makes it relatively unsuitable for for struvite recovery and fertilizer manufacturing. Sample AR, on the other hand, with the highest MgO concentration and the lowest iron and chromium concentration, is ideal for the production of both refractory materials, struvite and fertilizers. Such a high-quality magnesite ore is potential for exportation. Despite having a high proportion of magnesite, sample DM is not suitable for the production of refractory materials and fertilizers due to its low concentration of MgO and large concentrations of calcium oxide, silica and chromium. Furthermore, the presence of arsenic in the sample DM narrow down its application.\u003c/p\u003e"},{"header":"5. Declarations","content":"\u003cp\u003e\u003cstrong\u003eConflict of interests\u003c/strong\u003e: The authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding statement\u003c/strong\u003e: The authors did not receive support from any organization for the submitted work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e: There are no human or animal subjects in this article and ethics approval is not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e: All the data used to support the findings of this study are included within the article.\u003c/p\u003e"},{"header":"6. References ","content":"\u003col\u003e\n\u003cli\u003eAbali Y, Copur M, Yavuz M (2006) Determination of the optimum conditions for dissolution of magnesite with H\u003csub\u003e2\u003c/sub\u003e SO\u003csub\u003e4\u003c/sub\u003e solutions. 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Gems \u0026amp; Gemology\u003cem\u003e \u003c/em\u003e41(2):116-148. \u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"carbonates-and-evaporites","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"caev","sideBox":"Learn more about [Carbonates and Evaporites](http://link.springer.com/journal/13146)","snPcode":"13146","submissionUrl":"https://submission.nature.com/new-submission/13146/3","title":"Carbonates and Evaporites","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"magnesite, minerals, struvite, deposits, XRF, XRD","lastPublishedDoi":"10.21203/rs.3.rs-4128932/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4128932/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMagnesite (MgCO\u003csub\u003e3\u003c/sub\u003e) is a valuable mineral with wide industrial applications; thus, geochemical familiarity and deposit quality are critical for making the best use of these resources. Tanzania is reported to have magnesite deposits in at least 12 different locations; however, four of these were chosen at random for study. This study aimed to examine the mineralogical and elemental composition of rock samples from Chambogo (KL), Muriatata (AR), Lobolosoiti (MN), and Chikaza (DM) using x-ray fluorescence (XRF) and powder x-ray diffraction (XRD). XRF examination revealed that sample KL, AR, MN, and DM, respectively, contain 45.21%, 46.06%, 43.21%, and 43.21% of magnesium oxide. Besides MgO, all samples contained SiO\u003csub\u003e2\u003c/sub\u003e, Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, CaO and several trace elements as impurities, with only calcium oxide, iron, arsenic and chromium identified as impurities of concern. However, XRD analysis indicated magnesite as the major mineral phase in samples KL, AR, MN, and DM, with percentage concentrations of 65.2, 68.14, 63.87, and 68, respectively. \u0026nbsp;In all samples, strong peaks at 2θ~ 33\u003csup\u003eo\u003c/sup\u003e, 43\u003csup\u003eo\u003c/sup\u003e, 54\u003csup\u003eo \u003c/sup\u003eand 55\u003csup\u003eo\u003c/sup\u003e, confirmed the crystalline nature of magnesite. Calcination of these samples however, resulted in peak shift and phase change, with main diffraction peaks generated at 2θ~ 36.9\u003csup\u003eo\u003c/sup\u003e, 42.9\u003csup\u003eo\u003c/sup\u003e and 62.3\u003csup\u003eo\u003c/sup\u003e, confirming the formation of crystalline MgO. Despite considerable contamination levels of CaO, iron, chromium, and arsenic in the samples, all samples had enough magnesite to be mined for industrial use.\u003c/p\u003e","manuscriptTitle":"Assessment of Tanzania Magnesite’s Suitability for the Struvite Recovery and Other Industrial Applications","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-10 17:40:00","doi":"10.21203/rs.3.rs-4128932/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-05-08T16:29:34+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-05-06T10:13:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"ebecf050-fb19-4de8-a475-8b2777110078","date":"2024-04-22T12:05:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"805c2ecf-e5ad-4ec2-95c5-c6bd2ed91cd3","date":"2024-04-22T04:20:28+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-04-20T13:04:27+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"fc1b98f1-967a-4a38-8c77-0dad2916e601","date":"2024-04-19T16:30:08+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-04-07T18:16:22+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-04-07T17:53:31+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-04-05T09:32:11+00:00","index":"","fulltext":""},{"type":"submitted","content":"Carbonates and Evaporites","date":"2024-03-19T09:14:45+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"carbonates-and-evaporites","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"caev","sideBox":"Learn more about [Carbonates and Evaporites](http://link.springer.com/journal/13146)","snPcode":"13146","submissionUrl":"https://submission.nature.com/new-submission/13146/3","title":"Carbonates and Evaporites","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"5c7ab1d7-ee86-480f-ad5c-8b5f1aa9dccf","owner":[],"postedDate":"April 10th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-08-01T17:11:09+00:00","versionOfRecord":{"articleIdentity":"rs-4128932","link":"https://doi.org/10.1007/s13146-024-00989-8","journal":{"identity":"carbonates-and-evaporites","isVorOnly":false,"title":"Carbonates and Evaporites"},"publishedOn":"2024-07-23 16:15:58","publishedOnDateReadable":"July 23rd, 2024"},"versionCreatedAt":"2024-04-10 17:40:00","video":"","vorDoi":"10.1007/s13146-024-00989-8","vorDoiUrl":"https://doi.org/10.1007/s13146-024-00989-8","workflowStages":[]},"version":"v1","identity":"rs-4128932","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4128932","identity":"rs-4128932","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}