apatite concentrate
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The studies were performed suggesting that the cause of P2O5 losses during apatite-staffelite ores (ASO) treatment are due to non-selective flocculation of fine classes during flotation. When using strong flocculants, special preparation of condensed slurries is necessary, ensuring their deflocculation before the flotation process. A scheme and mode of preparation of fine classes for the flotation process have been developed, including thickening of the classification overflows using strong anionic flocculants and deflocculation of the thickened product before the flotation process with reagents-dispersants used in the basic flotation mode. A mode of preparation of slimes of ASO ores for flotation is proposed, including thickening of the discharge of the classification operation using the anionic flocculant “Praestol-2540”, conditioning of the condensed product with additions of liquid glass and caustic soda in a ratio of 1 : 1, dilution and re-thickening of deflocculated slimes, consolidation and flotation thickened sludge and sand. The big laboratory tests have shown that the application of the developed regime provides a total increase in the extraction of P2O5 from ore from 70,1 to 71,5 % with an increase in the P2O5 content in apatite concentrate from 37,1 to 37,8 %, which makes the developed technology promising for processing refractory ASO at Kovdorsky GOK.

This paper summarizes the findings of the research aimed at the development of a new method for the integrated processing of naturally occurring and anthropogenic rare-earth raw materials based on the decomposition of rare-earth element (REE) concentrates in the presence of sulfocationite. Sorption and desorption of REE cations on a strongly acidic ion exchanger, sorbent regeneration, and REE recovery from eluates are discussed. A virtually zero-waste integrated process for apatite concentrate is proposed. The generalization of the research findings is aimed at demonstrating the prospects and universality of the proposed resource-saving and environmentally safe approach to the processing of various types of naturally occurring and anthropogenic rare-earth mineral feeds. The new methodology made it possible to develop a number of new hydrochemical processes united by a single approach, providing a qualitative increase in the processing performance of various types of rare-earth mineral feeds. The theoretical foundations of a unified approach to the processing of a wide range of minerals can significantly accelerate and cheapen the implementation of specific process circuits, significantly reduce reagent consumption and waste generation, simplify the separation of rare earth elements and impurities, and the separation of rare earth elements from naturally occurring radionuclides, fluorine, and phosphorus. The study was funded by the Kolarctic CBC 2014-2020 program, Project KO1030 SEESIMA — Supporting Environmental Economic and Social Impacts of Mining Activity.

Four procedures based on closed-vessel microwave-assisted wet digestion with different oxidative reagents, including HNO3 (P1), HNO3 + H2O2 (P2), aqua regia (P3) and Lefort aqua regia (P4), for preparation of calcium (Ca)-rich materials prior to determination of total concentrations of Al, Ca, Cd, Fe, Mg and P by inductively coupled optical emission spectrometry (ICP OES) were compared. It was found that digestion with Lefort aqua regia (P4) provided the best results for all examined elements, i.e., precision of 0.30–4.4%, trueness better than 2%, recoveries of added elements between 99.5–101.9%, and limits of detection within 0.08–1.8 ng g−1. Reliability of this procedure was verified by analysis of relevant certified reference materials (CRMs), i.e., Natural Moroccan Phosphate Rock—Phosphorite (BCR-O32). Additionally, selection of appropriate analytical lines for measurements of element concentrations, linear dynamic ranges of calibration curves and matrix effects on the analyte response were extensively investigated. Finally, the selected procedure was successfully applied for routine analysis of other Ca-rich materials, i.e., CRMs such as NIST 1400 (Bone Ash), CTA-AC-1 (Apatite Concentrate Kola Peninsula) and NCS DC70308 (Carbonate Rock), and six natural samples, such as a dolomite, a phosphate rock, an enriched superphosphate fertilizer, pork bones, pork bones after incineration, and after steam gasification.

"Water treatment technologies involving pre-treated industrial effluents without transporting them to the tailing dump are of interest primarily from an environmental point of view, as they reduce the environmental burden. The paper studies the possibility of purification of process waters from apatite concentrate production from suspended particles and water-soluble impurities using polyacrylamide flocculants. By studying the processes of adsorption of H+ and OH- ions from aqueous solutions, the acid-base properties of the surface of the solid phase of the most polluted technological product - the drain of the apatite concentrate thickener - the mineral composition of which is 90% apatite have been studied. The influence of the reagents present in the processing technology on the quantitative ratio of acid-base centres on the apatite surface has been evaluated. It has been shown that the interaction of these reagents with the mineral creates prerequisites for a greater efficiency of the anionic flocculant. The electro-surface properties of apatite treated with various reagents were studied using the laser Doppler electrophoresis method. The mechanism of fixation of ions present in the dispersion medium on the surface of apatite was studied by infrared spectroscopy. In order to determine the conditions under which various flocculants are in the most ionized state, studies were conducted on the change in the viscosity of the polyelectrolyte solution at different pH values. The position of the isoionic point for samples of cationic and anionic flocculants in the presence of reagents used in the apatite flotation and dehydration of apatite concentrate was studied. A research has been carried out on ""model"" and real suspensions in circulating water for a number of cationic, anionic and nonionic flocculants. The kinetic and concentration dependences of the flocculating capacity of the studied reagents were determined, which confirmed the high efficiency of the anionic type reagents"

"The use of recycled water supply technology in mineral dressing plants solves current environmental and economic problems for the mining and processing industry. Usually, water treatment takes a long time and requires constructing large-volume tailing dumps. The paper proposes a technology of a partially closed water circulation with the purification of watered production waste from suspended particles and water-soluble impurities that negatively affect the flotation process, based on the regularities describing the interaction of flocculants with the phases of a heterogeneous system of process waters. The authors have determined the most effective reagents providing optimal indicators of recycled water. The proposed technology is implemented in hardware in a radial thickener and eliminates the discharge of process water into an external tailings dumps facility, which will reduce the area occupied by production waste. Based on the particle size distribution data for various preliminary treatment options, differential and integral particle size distribution curves have been obtained. Analytical expressions of the obtained curves have been used to create discrete functions of volume fractions of particles with different sizes when constructing a model of the initial feed. The hydrodynamic processes of highly diluted suspension flows in the thickener’s body were studied using computational experiments on a model developed in the ANSYS Fluent software package, which is based on the real 3D geometry of a radial thickener. To build the geometry, the authors used a standard module GAMBIT. A computational experiment on cleaning the apatite concentrate discharge was performed on a virtual stand. The distributions of the concentrations of volume fractions of particles and the velocities of their movement in the thickener’s volume were obtained. The results of laboratory studies and computer simulation data allow the authors to tell about the prospect implementation of the technology of intra-plant water circulation, which will reduce by 10% the amount of wastewater discharged into the tailing dump. The use of the most efficient reagents will provide optimal water parameters for the content of suspended particles and hardness cations and, ultimately, will increase the technological and environmental performance of the Khibiny apatite-nepheline ores processing."

In this work, measures are being developed to reduce the noise level at the workplace of a mechanic-repairman to replace filter cloth. Based on the results of production control and a thorough assessment of working conditions, the source of noise was determined to be the VDN-17 fan. The analysis of Russian and foreign studies in the field of the negative impact of noise on the human health and methods of dealing with industrial noise has been carried out. As a result, a technical method of reducing negative impact of noise was selected and the acoustic efficiency of the muffler for the VDN-17 fan was calculated.

Apatite-nepheline ores of the Khibiny deposits contain the largest phosphorus-bearing resources in the world, and, at the same time, they contain associated valuable components in the rock-forming minerals — apatite, nepheline, sphene and titanium magnetite. Intensive development of the Khibiny deposits with production of only apatite concentrate and a small part of nepheline concentrate resulted in the accumulation of over 1.0 billion tons of wastes in tailing storage facilities and dumps during 90 years of JSC Apatit operation. The possibility of increasing the efficiency of the use of the main concentrates of apatite-nepheline ores of the Khibiny deposits and wastes for their processing is considered through the use of technological developments of the FRC KSC RAS, JSC RIFI and JSC Apatit to obtain traditional and new target products. A fundamentally new approach to the problem of sustainable use of natural resources is focused on establishment of the whole production chain in the region, from mining and processing operations to manufacturers of final high technology products (rare-earth products, welding and construction materials, coloring agents and other materials). They also determine the level of industrial technical progress. Keywords: Khibiny apatite-nepheline ores, mineral raw materials, extraction and processing, new materials

Intermediate processing products of apatite raw materials, such as the process solutions of phosphoric acid (PA) containing the in-demand rare-earth elements (REE) of heavy and medium-light groups, are a promising source of rare-earth metals. Apatite concentrate typically has low rare-earth metals grades (up to 1 %); therefore, sufficient economic value may only be achieved with those technologies that yield individual rare-earth metals without modifications in the underlying apatite raw materials process. Extraction methods have significant technological advantages, mainly due to the simplicity of implementation and the possibility of accelerated industrial-scale adaptation. Rare-earth metals recovery from PA process solutions into the organic phase based on di-2-ethylhexylphosphoric acid (D2EHPA) is associated with the simultaneous extraction of titanium (IV). Additional separation processes are, therefore, required in view of the presence of titanium in the REE extract. It has been found that effective titanium recovery from the organic phase is achieved by using oxalic acid with the concentration of 0.25 mol/l at the phase ratio of 0.5 and the mixing rate of 400 min–1. The content of impurity elements in the concentrates of individual REM compounds obtained of does not exceed 10–4 %. The complex processing operations performed for obtaining individual rare-earth metals represent a complete technology for the integrated processing of apatite raw materials. The work was carried out with the financial support of the Russian Science Foundation (project No. 19-19-00377).