Phosphorite Processing Research Articles

Processing of phosphorites with extraction of phosphorus, obtaining calcium carbide and ferroalloy

The article considers the results of studying the thermodynamic computer modeling of the interaction of phosphorite (Karatau basin, Kazakhstan) with carbon and coke performed using the HSC-10 software package and electric smelting of the phosphorite with coke and steel shavings in an arc furnace. The modeling allowed us to determine the equilibrium extraction degrees of phosphorus into gas (Р<sub>2</sub>, Р<sub>4</sub>), silicon into ferroalloy in the form of iron silicides (FeSi<sub>2</sub>, FeSi, Fe<sub>3</sub>Si, Fe<sub>5</sub>Si<sub>3</sub>, Si) and calcium into CaС<sub>2</sub>. At temperatures above 1500 °C, regardless of the amount of iron, the extraction degree of phosphorus into gas is more 99%. The resulting ferroalloy contains 21.2-23.8% of Si, 1.6-2.8% of Al; the calcium carbide has a capacity of 288-325 dm<sup>3</sup>/kg. The extraction degree of silicon into the alloy was 89.8%, calcium in CaC<sub>2</sub> – 72.5%, phosphorus into gas – 99.4%. The ferroalloy, formed at the electric smelting of the Chulaktau phosphorite together with coke and steel shavings and containing 24.9-29.8% of Si, is FS25 grade ferrosilicon, and the formed calcium carbide has a capacity of 278-290 dm<sup>3</sup>/kg and belongs to the third and second grades. The developed technology makes it possible to increase the degree of phosphorites’ comprehensive use two times (up to 87.5%).

Processing of phosphorites and additives with researching their thermodynamical properties

In this article, scientific research on the production of thermophosphate fertilizers was carried out on the basis of thermo-alkaline activation of Central Kyzylkum waste phosphorite with mineralized mass and alkali metal salts, namely NaCl, KCl, Na2SO4, K2SO4, Na2CO3, K2CO3 and silica at high temperature. In this case, samples are heated in muffle furnaces at temperatures of 800°C, 900°C, 1100°C, 1200°C and for 30 min, 60 min, 120 min. The total P2O5, assimilable P2O5, total СaO and total СO2 forms of the sintered tablets were investigated. As it can be seen from the experiments conducted with mineralized mass phosphorite, alkaline salts and quartz sand, it was found that the assimilated form of СaO, P2O5 and the degree of decarbonation rose with increasing temperature and time.

INFLUENCE OF THE RATE OF IRON HEXATIANOFERRATE ON ITS SORPTION ABILITY IN RELATION TO SILVER, INDIUM AND GALLIUM CATIONS

The processing of phosphorites into elemental phosphorus is accom-panied by the formation of waste - cotrile "milk", in which indium, gallium, and silver are present. This waste can be considered as a cheap raw material for the production of rare and precious metals. In the scientific literature there are data on the sorption capacity of hexacyano-ferrates of iron, which has a crystal lattice with a channel diameter from 3.0 to 3.5Å. Investigation of the sorption process in the model system "Fe4[Fe(CN)6]3·10H2O - Ag+- In3+- Ga3+ - H2O" depending on the norm of iron hexacyanoferrate (sorbent). The initial concentration of silver, indium and gallium ions and their residual content in solutions were determined using the atomic absorption spectrophotometer "PerkinElmer Analyst 400" (USA). The microstructure of the initial iron hexacyanoferrate and iron hexacyano-ferrate, after sorption, was studied on the CarlZeissFESEM and JEOL brand "JXA-8230" (Japan). With a ratio to T:W equal to 1.75-2.5:100, the degree of sorption of Ag+ with iron hexacyanoferrate is 99.5 and 99.8 %. The highest degree of sorption (96.75%) of In3+ ions can be obtained with a sorbent weighing 3 g per 100 g of solution at 60oC. A high degree of sorption of Ga3+ cations is achieved at low (0.5:100 wt. h.) and high (3:100 wt. h.) consumption of iron hexacyanoferrate. It was revealed that iron hexacyanoferrate exhibits sorption properties simultaneously with respect to mono- and trivalent metals, and the basic laws of their sorption were established.

Important environmental social governance risks in potential phosphorite mining in Estonia

The country`s national resources must be used sustainably, considering the environmental, social, and economic aspects. Estonia's potential reserves of phosphorite are among the largest in Europe, but its extraction has been a historically sensitive issue. The current study was focused on Estonians` perceptions about the potential extraction and processing of phosphorite in four stakeholder groups: the local community, the business sector, policymakers and environmental activists. An Environmental Social Governance (ESG)-risks based survey was conducted that examined the significant environmental, social and governance risks that stakeholders would like to know if such production exists. The results obtained reveal that environmental risks were more important and social risks were less important. In the cross-stakeholder comparison, environmental risks were most important for the local community and environmental activists, social risks were most important for the local community and less important for environmental activists, with the business sector valuing the importance of governance risks the most. Policymakers had more or less a similar assessment in all ESG categories. To address the multifaceted challenges of phosphorite uptake, the authors suggest creating a framework that will act as a guideline for policymakers in the future on phosphorite resource sustainable use.

Properties and Applicability of Technical α-Quartz in the Glass Industry

The phosphate ore in the Polpin field contains up to 30% silica. The silica acts as a ballast in direct acid processing of phosphorite into mineral fertilizers. It is desirable to remove the silica from the product. The possibility of using silica as raw material in the glass industry is substantiated, and for this purpose the phase and chemical compositions of the silica were determined and compared with the current technical specifications.

Graphic Study of the Dihydrate–Hemihydrate Process for the Synthesis of Phosphoric Acid According to the Diagram of the CаO–P2O5–SO3–H2O System

A graphic analysis of the processing of phosphorites from Koksu (Karatau deposit) into extraction phosphoric acid (EPA) by the dihydrate–hemihydrate method was performed according to the equilibrium solubility diagram of the CaO–P2O5–SO3–H2O system. It was shown theoretically that EPA with 30.0% P2O5 can be obtained for practical purposes from common phosphate raw material of Koksu (24.5% P2O5). The main concentration and mass parameters that underlie the experiments on process development were evaluated.

Precursors of volatile organic compounds emitted during phosphorite processing

Precursors of volatile organic compounds emitted during phosphorite processing The composition of solvent-soluble organic matter of phosphorite, which is a precursor of volatile organic compounds emitted by the fertilizer industry, was studied. A benzene-methanol mixture and chloroform were used for the extraction of free and bound bitumen from phosphorites, respectively. The separated bitumen fractions were characterized qualitatively by GC-MS and quantitatively by GC-FID. n-Alkanes, n-alkenes, fatty acids and isoprenoids were identified in the extracts. The main components were n-alkanes and n-alkenes, constituting over 80% of the total bitumen determined. An unexpected presence of n-alkenes only in the free bitumen fraction was found. The possible source of ill-smelling substances evolved during treatment of phosphorite with H2SO4 was discussed.

Distribution, Speciation, and Extractability of Cadmium in the Sedimentary Phosphorite of Hahotoé-Kpogamé (Southern Togo)

The geochemistry and extractability of Cd in the phosphorite deposits of Hahotoe-Kpogame (southern Togo) have been studied using various methodologies such as Cd distribution in profiles, grain-size dependence analysis of Cd content, Cd localization using scanning electron microscopy (SEM), sequential acid extraction, and a leaching experiment with artificial seawater. Results demonstrate that in the phosphorite deposits of Hahotoe-Kpogame, Cd is enriched by a factor of 157 compared to shale and by a factor of 3 compared to average world phosphorite composition. The main carrier of Cd appears to be apatite. This is evidenced by significant high positive correlations between the Cd content and P2O5 (in bulk sedimentr = 0.7 and in the 1–0.2 mm fraction r = 0.9). The grain-size dependence of Cd contents (concentrations decreasing with decreasing grain size) and SEM analysis supports these conclusions. Secondary Cd carriers include calcite, goethite, and various bone fragments. Sequential extraction tests with acetic acid and EDTA show an extraction rate reaching up to 40%. Leaching experiments with artificial seawater show evidence of Cd release in seawater. This leads to the conclusion that the processing of phosphorite by wet sieving using seawater and dumping of phosphorite tailings into the coastal waters of Togo can be a major source of marine pollution with Cd.

The Geochemical Characterization of Mine Effluents from the Phosphorite Processing Plant of Kpémé (Southern Togo)

Sedimentary phosphorites are being exploited in southern Togo. The ore is processed to high-grade purified commercial phosphorite by wet sieving, using water pumped directly from the sea. The resultant muddy tailings are dumped directly into the sea without any pretreatment. We have separated the solid and liquid phases of the muddy tailings and characterized their metal contents. Leaching tests were conducted with weak acid and saline water to evaluate the solubility and the potential bioavailability of various metals. The results show that the purification process leads to the enrichment of certain metals (Cr, Cu, Ni, V, Zn, Ba, Sr, Fe, and Al) in the tailings due to their association with the clay minerals, whereas Cd, Th, and U are enriched in the purified apatite-rich phase. The leaching tests showed that the solubility of metals generally increases when salinity increases or when pH decreases. Thus, the processing of phosphorites with sea water and the dumping of phosphorite tailings into the sea represent a serious potential risk for the marine ecosystem and for human health through the food chain.

Uranium and Potentially Toxic Metals During the Mining, Beneficiation, and Processing of Phosphorite and their Effects on Ground Water in Jordan

Representative samples were collected from various stages of phosphorite mining and beneficiation from the Al-Abiad and Al-Hasa mines in central Jordan and the Eshidiyya mine in southern Jordan. After open pit mining, the rock is crushed and dry-sieved to pass 12 mm in order to concentrate the ore. The sieved material is then agitated, washed with fresh water, and wet sieved to pass 4 mm. Samples were analyzed by ICP-MS for major elements and As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se, U, V, and Zn. We found that throughout the above-mentioned processes, potentially toxic metals are partially removed from the ore. However, most of the contaminants are still retained within the final phosphorite product. The slime and slime water were analyzed; we found no effect of the slime water on the nearby ground water regime. The phosphorite is converted to fertilizer through reactions with sulfuric acid and then ammonia to produce diammonium phosphate (DAP). Gypsum is produced as a reject. The potentially toxic metals follow the behavior of P and are enriched by a factor of more than 1.5 in the DAP compared with the input phosphorite. The trace metal content in the phosphogypsum is very low.