Phosphorite Ore Research Articles

Interface migration and alloying mechanism of Fe and P for ferrophosphorus alloy production during the carbothermic reduction of phosphorite

Ferrophosphorus (Fe–P alloy), a byproduct in the carbothermal reduction of phosphorite for yellow phosphorus production, has remarkable potential application as foundational precursors to prepare advanced catalysts and energy materials. However, the gas-solid-liquid equilibrium in the reduction smelting of phosphorite and hematite is intricate, and the reduction, volatilization, and alloying mechanisms of Fe and P at higher temperatures should be given close attention to optimize the production of yellow phosphorus vapor and Fe–P alloy. In this study, the reduction smelting behaviors of fluorapatite and hematite in the phosphorite ore were investigated. Carbothermic reduction reactions of Ca5(PO4)3F with and without Fe2O3 are calculated, establishing theoretical fundamentals. The phase and microstructure evolutions of Ca5(PO4)3F and Fe2O3 are researched. This work also emphasizes the interfacial element migration to clarify the reduction, volatilization, and alloying of Fe and P by considering the solid-solid interface of Ca5(PO4)3F–Fe2O3 and the gas-liquid interface of P2 vapor-metallic Fe.

Alkali-activated geopolymers based on calcined phosphate sludges and metakaolin.

The extraction of phosphorite ore in Tunisia has resulted in the discharge of substantial amounts of phosphatic sludge into the region's water system. To mitigate this environmental issue and prevent heavy metal leaching, a geopolymerization process was employed using two types of Tunisian calcined phosphate sludges (Cal-PS1 and Cal-PS2) as substitutes for alkali-activated metakaolin. This study aimed to investigate and compare the physical and mechanical properties of the resulting geopolymers. The optimal substitution ratio of metakaolin with calcined phosphate sludge was determined to be 1.5, equivalent to 20 wt.% of calcined phosphate sludge. Compressive strength tests conducted after 28 days of curing revealed values of 37 MPa for Cal-PS1 specimens and 28 MPa for Cal-PS2 geopolymers while compressive strength of geopolymers soaked in water for 28 days showed a decrease with the addition of phosphate sludges. The specific surface areas of Cal-PS1 geopolymers ranged from 16.3 to 16.9 m2/g and from 17.62 to 18.73 m2/g for Cal-PS2 specimens exhibiting a mesoporous structure. The elasticity modulus of the geopolymers was found to increase with the increase of the apparent density of geopolymers and with the sludges content but it tended to be lower than the Portland cement elasticity modulus. Leaching test was conducted to evaluate the potential environmental applications of the geopolymers. This test demonstrated effective containment of heavy metals within the geopolymers' network, except for low levels of arsenic.

Acid-Free Processing of Phosphorite Ore Fines into Composite Fertilizers Using the Mechanochemical Activation Method

The relevance of involving substandard raw materials for the production of composite phosphorus-containing fertilizer production is significant due to the problem of providing food products for the growing population of the Earth. The main raw materials for phosphorus and composite phosphorus-containing fertilizer production are natural phosphate ores—phosphorites. However, in the process of mining and crushing, ~55–60% phosphorite ore fines are formed—a fraction of less than 10 mm, which is unsuitable for traditional processing into composite phosphorus-containing fertilizers. This article presents the results of physicochemical studies of the substandard fine fraction of phosphorite ore and the results of the studies of the possibility of their direct processing into phosphorus and composition of phosphorus-containing fertilizers using methods of mechanical and mechanochemical activation in the “Activator 4” planetary mill. The findings of the studies performed confirm the rather high efficiency of phosphorite ore fines’ mechanical activation and phosphorite-containing mixtures’ mechanochemical activation, which make it possible to significantly increase the content of assimilable phosphorus pentoxide P2O5 in composite phosphorus-containing fertilizers. The proposed innovative technology has fundamental differences from existing technologies, since the mechanochemical activation of a mixture of phosphorite ore fines and functional components will allow for direct acid-free and waste-free processing into phosphorus and composite phosphorus-containing mineral fertilizers.

Gold in phosphorites: Accumulation forms and practical significance

Research subject. The gold-bearing potential of modern (oceanic) and ancient industrial types of phosphorite ores, including aphanitic, microgranular, granular, nodular, shell and karst. Aim. To assess the ability of phosphorites to accumulate gold to industrial concentrations. This issue has been actively discussed in the geological community in recent years due to the advent of high-precision methods for studying matter. Methods. Russian and foreign publications, unpublished geological data, as well as the authors’ data collected over a 30-year period of studying phosphorites. Results and discussion. In the section, 14 packs of rocks were identified, which are represented by 6 lithological types of secondary dolomites. Their distribution along the section, along with the presence of characteristic faunal remains, made it possible to establish three members in the section, which can be correlated with the Katian, Hirnantian, and Ruddanian stages of the General Stratigraphic Scale. Conclusion. Conditions for the possible joint accumulation of phosphates and gold are manifested in black shale basins, as well as in shelf shallow waters with glauconite-sand sediments. However, due to significant differences in the natural features of gold and phosphates, their industrial clusters are formed separately from each other. This is evidenced by the insignificant accumulation of phosphorus in the ores of gold deposits of black shale formations,as well as its low-quality concentrations in industrial phosphorite beds of phosphorite-bearing basins. For gold, phosphorites are only temporary collectors, the productivity of which depends on the combination of many, frequently random and slightly related factors.

Analysis of the aspiration system and gas cleaning for the cooling zone of the sintering machine for phosphorite ore

This study describes the gas emission aspiration and purification system, which is a crucial component of the life support system for a mining and processing plant. The aspiration system aims to maintain favorable working conditions and prevent the increase of dust content and harmful emissions in the air of working areas beyond the maximum permissible values. This study addresses the cleaning of aspiration and gas emissions in the technological zones of sintering machines during the sintering of ore phosphate material. It provides technical solutions for cleaning gases during the sinter cooling process, considering the condensation of moisture from gases inside exhausters. The text also reveals the technological parameters for the functioning of foam apparatuses, cyclones, and splash catchers. The process of cleaning gases in the technological cooling zone of the sintering machine is carried out in two parallel foam apparatus, using both dry and wet methods.

The REY geochemistry of phosphorites during metamorphism of the Haizhou Group, NW Yangtze Block, China

Rare earth elements (REE including Y—REY) in phosphorites have been used widely as a proxy for seawater chemistry at the time of their formation. However, it is unclear whether metamorphism can lead to REE remobilization and alteration of primary seawater signatures recorded in phosphorites. In this study, we examine similarly aged metamorphosed phosphorite ore deposits from the northeastern margin of the Yangtze Block (Jinping and Xinpu ore sections), with contemporaneously deposited unmetamorphosed equivalents in the southwestern margin of the Yangtze Block (Weng'an ore section). New insights have been provided into the migration of rare earth elements and the redistribution of Zn and O isotopes in metamorphosed phosphorite, which suggests that the varying degrees of metamorphic fluid–rock reaction during the metamorphism process significantly reduced the δ18O value of phosphate (13.7‰ ± 2.2‰ of Jinping phosphate and 7.3‰ ± 1.8‰ of Xinpu phosphate) and added light Zn isotope. These metamorphic fluids were likely generated by the metamorphic dehydration of upper slab uplift during the plate subduction in the Triassic. The negative correlation between the O (and Zn) isotope compositions and REY contents in P-rich rocks suggests that REY were likely re-enriched during the recrystallization process of apatite. Preferential migration of LREE led to significant LREE and MREE enrichment in Haizhou metamorphosed P-rich rocks compared to Weng'an unmetamorphosed phosphorites.

TECHNOLOGY FOR PRODUCING THERMOPHOSPHATE PRODUCTS BASED ON PHOSPHORITES WITH ADDITIVES OF ALKALINE SALTS

The essence of this work is to study the microstructure and mechanical properties of mixed salts of alkali metals, such as sodium and potassium, phosphorites of the Central Kyzylkum of various compositions. This raw material, low in phosphorus and rich in carbonate and chlorine, is not suitable for acid treatment. To obtain high-quality phosphate fertilizers from raw materials, it must first be enriched. At the Kyzylkum Phosphate Plant, multi-stage enrichment is carried out: crushing, dry enrichment, chlorine removal, sintering to remove CO2. One of the promising areas for the processing of phosphate raw materials of this type is heat treatment, based on the destruction of the crystalline structure of the mineral, which is indigestible by plants, during thermal activation. The work is aimed at obtaining a thermophosphate fertilizer, which is insoluble in water at different temperatures and times in optimal proportions with sodium chloride, sulfate, potassium carbonate, chloride, sulfate salts, sylvinite and silicon oxide/coal, which are more active. The regularity of the influence of temperature and weight ratios of the mineralized mass from the fractions of phosphorite ore of the Central Kyzylkum: silicon oxide/coal: sodium salts on the assimilable phosphorus in thermophosphate fertilizer is shown, as well as the fact that the digestibility of phosphorite ore of the II-layer is higher than that of other raw materials. An increase in the content of assimilable phosphorus in synthesized primary phosphorus thermophosphate fertilizers with an increase in temperature and time is substantiated at equal weight ratios of phosphorite ore of the II layer: silicon oxide/coal: sodium salt.

Method of obtaining pure organo-mineral fertilizer and its ecological investigation of the influence on soil fertility

The article discusses the soil-improving properties of an environmentally friendly organo-mineral fertilizer (OMF) obtained on a scientific basis at the Institute of Chemistry of the Academy of Sciences of Turkmenistan. The main goal of the study is to obtain an environmentally friendly OMF from chicken manure, which accumulates in large quantities on poultry farms and pollutes the environment, as well as to study the effect of the resulting fertilizer on the humus composition of the soil. Broiler chicken manure, microbiological preparation Nourivit Plus and phosphorite ores from the deposit of the Magdanly-Kugitan region of the Durnaly site were used as raw materials and their chemical compositions were determined (humidity, ash content, total organic matter, total nitrogen, phosphorus, and potassium and pH environment). The composition of bird droppings was found to contain a sufficient amount of organic substances and such important nutrients as nitrogen, phosphorus, and potassium. Under laboratory conditions, a scientific method for obtaining an environmentally friendly OMF was studied. Chicken manure used as raw material was neutralized from weed seeds and helminth eggs. Processing on the basis of waste-free technology of waste generated in poultry farms, an environmentally friendly, cost-effective, soil-improving OMF was obtained. The soil-strengthening properties of the obtained OMFs were studied at the Turkmen Agricultural University named after SA Niyazov on 3 plots of agricultural land measuring 1 x 6 meters. Samples were taken for analysis from each of the 3 soils before and after the application of OMF. An agrochemical analysis of the soil and a quantitative analysis of substances soluble in it were carried out. As a result, the elemental and humus composition of soil samples was determined before and after fertilization, and as a result it was proved that it is possible to increase the amount of humus in the soil from 0.12% to 2.17%.

Froth flotation separation of phosphate ore using a novel hammer-like amidoxime surfactant

Phosphate fertilizer, as a necessary nutrient for crops in agriculture, plays a vital role in addressing global food security concerns. The source of phosphate fertilizer is mainly obtained through the production of phosphate ore, which has caused widespread concern. However, in the traditional process, the low production efficiency and high dosage of common surfactants have severely restricted the development and utilization of phosphate rock resources. In this work, a new designed hammer-like amidoxime surfactant (DPA) was characterized and introduced as an outstanding collector to recover high quality phosphate ore. The micro-flotation tests indicated that DPA had more excellent collecting ability and selectivity(The phosphorite recovery was always lower than 15%) than common monomolecular collector 1-dodecylamine (DA). Bench-scale flotation tests showed that a high quality phosphorite concentrate with higher grade and recovery (33.65% and 79.46%, respectively) could be enriched using lower dosage DPA. Economic estimate for a 5000 t/d phosphorite ore concentrator would result in an annual profit increase of approximately $8675330.65 by DPA collector. Density functional theory(DFT) calculations revealed that DPA reacted with Nucleophilic reagent (Phosphorite) by the reactive site of –CH2NH(CH2)2C(NOH)N+H3 group and more easily absorbed on the surface of Phosphorite than DA. Therefore, the above results prove that amidoxime surfactant DPA is an efficient and economic collector to recover high quality phosphate ore, which provides an important guarantee for the production of phosphate fertilizer.

Sources of rare earth elements and yttrium in the early Cambrian phosphorites in Zhijin, southwest China

The early Cambrian Zhijin phosphorite in Guizhou province, China, has high rare earth elements and yttrium (REY) contents of up to 2500 ppm, with heavy REY (HREY) accounting for ∼30 % of the total REY. However, their REY sources are not well-determined. Herein, elemental geochemistry and Sr–Nd isotopes of phosphorites in four sections from the Zhijin phosphorite ore area were investigated, primarily to constrain the contributions of seawater and terrestrial REY sources to the REY enrichment in these phosphorites. Zhijin phosphorites have high Y/Ho (45–63) and seawater signature’s 87Sr/86Sr(i) ratios (0.7085–0.7092), suggesting a partial contribution from seawater-sourced REY. On the other hand, Zhijin phosphorites have εNd(t) values of −8.6 – −6.8, indicative of the great influence from continental weathering. The Y/Ho ratios exhibit negative correlations with their Zr contents and SmN/YbN ratios; meanwhile the 87Sr/86Sr(i) ratios exhibit positive correlations with their Sr contents and REY contents, indicating that terrestrial source contributions played an important role in REY enrichment in Zhijin phosphorites. Furthermore, the provenance of Zhijin shales indicates the terrigenous granite weathering, during which the regolith-hosted REY could be transported to Zhijin shallow seawater, providing abundant REY to Zhijin phosphorites. We proposed that the REY enrichment in Zhijin phosphorites could be associated with high REY seawater induced by granite weathering. This study provides a new perspective on the relationship between granite weathering and marine REY deposition, which may be a common phenomenon in geological history but remains to be fully investigated in future.

Rare earth elements plus yttrium (REY) in phosphorites from the Tébessa region (Eastern Algeria): Abundance, geochemical distribution through grain size fractions, and economic significance

Rare earth elements and yttrium (REY) have gained greater attention for being largely used in various high-tech applications and green energies. Recently, supply shortage and high demand on REY led to target secondary resources such as phosphorites. Algerian sedimentary phosphorites, which are located mainly in the Tébessa region, Eastern Saharan Atlas, are relatively enriched in REY according to recent whole-rock analyses. The aim of this study is to explore variation of REY contents and other geochemical features with respect to particle size fractions. In addition, the economic significance of the P-deposits was assessed using new indicators, such as the outlook coefficient of REY composition (Coutl) and the percentage of critical element in total ΣREY (REYdef). Three friable whole-rock samples from two P-deposits (Djebel El Kouif and Kef Essenoun) were sieved and retained fractions (f) of <45 μm, 45–125 μm, 125–250 μm, 250–500 μm and >500 μm were analyzed for their major and REY contents using ICP-MS techniques. Principal Component Analysis (PCA) was applied on centred log-transformation (clr) data, which are adapted to such compositional dataset, as well as Variance Analysis (one-way ANOVA) technique. The results show that the samples yield P2O5 grades ranging from 20 to 36 wt% and total REY contents in selected 15 samples vary in the considered grain size fractions as follows: f<45μm = 325 ppm–719 ppm; f45–125μm = 309 ppm–893 ppm; f125–250μm = 314 ppm–1029 ppm, f250–500μm = 354 ppm–809 ppm, f>500μm = 308 ppm–652 ppm. The one-way ANOVA reveals that there is no significant difference of REY concentrations between the grain size fractions. However, the REY grades strongly based on both the studied deposits and the stratigraphic position of the hosting samples (p-value ≤ 0.01); this is also confirmed by PCA. REY geochemical signatures (normalized REY distribution patterns and Ce, Eu, and Y anomalies) are similar in the grain size fractions from the same hosting samples indicating synchronized evolution of all rock components, where REY distribution is mostly controlled by the depositional environment, irrespective of grain size in the rock. The Coutl coefficient shows values between 1.89 and 6.85 and REYdef varies from 47.44 % to 64.90 %. However, the upper sub-layer of Kef Essenoun phosphorites that yielded the lowest ∑REY contents, shows markedly the highest Coutl (6.61–6.85) and REYdef (64.31–64.90), pointing to more promising source for extracting individual critical REY elements, even in low P-grade phosphorite ores.

Acid treatment as a beneficiation method for phosphorite waste of Kyzylkum phosphorite plant

This article addresses matters relating to the recycling of waste from the Kyzylkum phosphorite plant in the form of phosphorite slimes, the mass of which exceeds 3 million tons at present. The treatment of slime with sulfuric acid having the concentrations from 2 g/l to 40 g/l made it possible to determine the most optimal concentrations (up to 10 g/l), at which the salts of alkali and alkaline earth metals, uranium and other elements are separated. This method permits obtaining a richer fraction of the useful component, phosphorus(V) oxide (up to 19.1%). At the same time, the pH value of the medium remains in the neutral range. Mass spectroscopy showed that such treatment with sulfuric acid having the concentrations up to 10 g/l allows selectively dissolving carbonates without decomposing phosphates. IR spectra of phosphorite slime after acid treatment do not contain absorption bands characteristic of CO32– groups. In accordance with the obtained results, a low-cost technological scheme for the phosphorite slime utilization was developed, followed by its introduction into the production process without violating the main technological regulations. The enriched slime fraction corresponds in quality to the burdened phosphorite ore and can be used as an additional product.

The Role of Medium Condition for Uranium Separation from Central Kyzylkum’s Low-grade Phosphorite after Sulfuric Acid Treatment

This article presents the results of separating radioactive elements, particularly uranium, from low-grade phosphorites of the Central Kyzylkum by low concentrated sulfuric acid solution, which is practically feasible at the Kyzylkum phosphorite combine (KPC). In world practice, uranium was extracted from phosphorite ore in the countries of the Middle East (Syria, Morocco, Algeria, Egypt) at the final stages of obtaining phosphorus fertilizers at metallurgical and chemical plants. The extraction of uranium from phosphorite ore is not practiced in Uzbekistan. The proposed method is fundamentally different from the above and is recommended to be applied at the initial stage of enrichment phosphorite ores in the enrichment plants. Studies have shown that the uranium completely passed into solution by treating phosphorite ore with weak concentrated sulfuric acid solution. Analyses of solution and sediment composition showed that the useful component, P2O5, remained in the sediment, increasing from 8.69% to 10.3%, while uranium passed into the solution with alkaline salts alkaline-earth elements. To obtain a finished product, the resulting enriched solution was added to the richer phosphorite ore. When performing the above processes, the pH of the medium was kept at the neutral level, which is of great practical importance for the implementation of this method with minimal economic costs using conventional inventory, corrosion resistance, and environmentally friendly phosphorus fertilizer.

Measurement of the phosphorite ore pulp density based on the image recognition method

Measurement of the phosphorite ore pulp density based on the image recognition method

Measurement of the phosphorite ore pulp density based on the image recognition method

Measurement of the phosphorite ore pulp density based on the image recognition method

Industrial and environmental safety in the extractive natural resource management for the needs of agriculture

The development of agriculture, primarily crop production, is determined by the availability of the necessary amount of phosphorus-containing fertilizers. In order to meet the needs of agriculture in phosphorus mineral fertilizers, extractive nature management is carried out in a number of regions of the world through the extraction and processing of apatite and phosphorite ores. At the same time, it is important to ensure the minimum permissible impact on the environment and natural water systems. For these purposes, methodological approaches are proposed, through which it is possible to monitor the state of objects and processes of mining production and take timely measures to ensure industrial and environmental safety. The author proposes a structure for complex research and monitoring of objects and processes in extractive nature management, based on the integration of interdisciplinary research related to the earth’s surface.

Evaluation of Estonian phosphate rock by flotation

Estonia holds the largest unexploited sedimentary phosphate rock reserves in the EU. Compared to other sedimentary and also igneous phosphate rocks the Estonian phosphorite is particularly outstanding by its remarkably low Cd(1–5 ppm) and trace U content (~50 ppm) and also contains valuable elements such as rare earth elements (REEs), which could be used in important high-technologies in the future. In this paper beneficiation by reverse flotation of the silicates for three types of Estonian phosphorite ores was investigated. The apatite concentrates with grades of over 33 wt% P2O5 at recoveries of 84.8 to 89.2% were achieved. The concentrates had low MgO contents and grades of FeO ranged from 1.29 up to 2.54 wt%. The study gives an overview of the specifics of enrichment of Estonian shelly phosphorite ores, provides a ground for future in-depth and pilot-scale experiments to find proper solutions for the Estonian phosphorite processing and will be applied in the feasibility studies of the phosphorite industrialization.

Two-Step Solvent Extraction of Radioactive Elements and Rare Earths from Estonian Phosphorite Ore Using Nitrated Aliquat 336 and Bis(2-ethylhexyl) Phosphate

Estonian phosphorite ore contains trace amounts of rare earth elements (REEs), many other d-metals, and some radioactive elements. Rare earth elements, Mo, V, etc. might be economically exploitable, while some radioactive and toxic elements should be removed before any other downstream processing for environmental and nutritional safety reasons. All untreated hazardous elements remain in landfilled waste in much higher concentration than they occur naturally. To resolve this problem U, Th, and Tl were removed from phosphorite ore at first using liquid extraction. In the next step, REE were isolated from raffinate. Nitrated Aliquat 336 (A336[NO3]) and Bis(2-ethylhexyl) Phosphate (D2EHPA) were used in liquid extraction for comparison. An improved method for exclusive separation of radioactive elements and REEs from phosphorite ore in 2-steps has been developed, exploiting liquid extraction at different pH values.

Chemical composition of ammo phosphate based on phosphoric acid processing of balanced phosphorite ore of central Kyzylkum

Chemical composition of ammo phosphate based on phosphoric acid processing of balanced phosphorite ore of central Kyzylkum

Research into phosphate mineral composition and waste phosphorite ore

Purpose. Theoretical and experimental studies of chemical and mineral composition and the structure peculiarities of phosphorites from Ukrainian deposits to define the degree of their suitability for other industries. Methods. The ore chemical composition was determined by conventional (wet) analysis using standard certified chemical reagents. The mineral composition was studied on the scanning electron microscope equipped with the attachment for the energy-dispersive electron microprobe analysis (EMPA) with the software for calculating the chemical composition of the studied sample microvolume. The petrographic analysis was carried out by the traditional methods of microscopic section preparation with subsequent identification and description of the minerals. The microscopic study of the original ore samples aimed at their mineral composition determination was conducted on the Nu optical microscope (Germany) both in transmitted and reflected light. The thin and polished sections prepared using the standard technology were used as samples. In the laboratory environment, the phosphorites were subjected to magnetic dressing in magnetic fields with different intensity. The experiments in the weak field were modelled with the help of the magnetic analyzer while the experiments in the strong magnetic field were modelled on the rotor separator. The flotation dressing method was studied on the laboratory mechanical flotation machine. Findings. It was found that phosphate nodules are rounded mineral formations of irregular shape; they consist of sand bound with the yellow-brown phosphate cement. Ore useful substance is a phosphorus-bearing mineral that by the element chemical composition corresponds to fluorocarbon-hydroxyl-apatite with the dominant content of Ca (45.23%), P (15.67%), and B (27.87%). The results of the integrated petrographic study of the phosphorite samples from the ore body of “Peremoha” area are presented. Originality.The study has revealed that phosphorus-containing substance in the phosphorite samples is the mass that cements barren minerals (mainly quartz, glauconite, calcite and plagioclase). Practical implications. According to the phosphate content level, the phosphorites from Malokamyshevatske, Iziumske and Sinichino-Yaremovske deposits can be treated as minerals for ferrophosphorus smelting. Keywords: ferrophosphorus, ore substance, phosphorite, mineral varieties, petrography, apatite