New experimental results have been obtained on the behavior of arsenic and other associated metals (Re and others) under conditions of oxidative and reductive sintering. It has been established that the extraction of arsenic strongly depends on the process temperature during oxidative sintering. The extraction of arsenic into dust media at 873 K is 50% and rhenium is 88–90%. The effect of excess air on the extraction of arsenic and rhenium into dust was studied: the higher the excess air coefficient, the more complete the extraction of arsenic and rhenium into the dust. The obtained data indicate that achieving a high level of arsenic extraction from the initial product is not possible during oxidative sintering. The best arsenic removal results were reached under the conditions of reductive sintering of initial material by natural gas. The extraction of arsenic into dust at 823 K was 88%, and at 1373 K arsenic is almost completely converted into dust. Obtained new experimental results have a fundamental importance for the selection and organization of a comprehensive technology for the processing complex in composition refractory gold-copper-arsenic-bearing products.

Dross from hot-dip galvanizing is an important source of pure zinc ingots and zinc oxide for use as mineral additives in animal and poultry feed. Thermodynamic calculations have shown the possibility of solving the issue of dross processing by roasting using CaCl₂ and NH₄Cl. The influence of the consumption of chlorinating reagents, the roasting temperature on the degree of sublimation of Pb, Fe, Ni, Cu and Cd has been investigated. It has been shown that the best results are achieved when roasting the dross with the simultaneous use of CaCl₂ and NH₄Cl in amounts of 6 and 15% by weight of the feed material. The optimal roasting parameters were established: T = 1000 °C, duration—60 min, air flow—0.1 L/min. Recovered pure zinc oxide composition (%) was: 0.05 Pb, 0.15 Fe, 0.06 Ni, 0.003 Cu and 0.001 Cd. The degree of sublimation of copper, nickel and iron chlorides was ~75%, with lead and cadmium at 90–98% of their initial amount in the dross.

Industrial technologies for processing tungsten concentrates using soda roasting or autoclave leaching are based on the production of alkaline sodium tungstate solutions that contain impurities such as silicon, phosphorus, arsenic, and others. The purification of these solutions from impurities requires the neutralization of excess soda or alkali with inorganic acids, which leads to the formation of chloride and sulfate effluents that are subsequently discharged into waste repositories. An analysis was carried out on existing methods for the production and processing of sodium tungstate solutions using HNO₃ and NH₃, as well as extraction and sorption techniques involving anion exchange resins. Currently, processes such as nanofiltration, reverse osmosis, and electrodialysis are being applied for water purification and the treatment of sulfate and chloride effluents. These processes employ various types of industrially manufactured membranes. For the purpose of electrodialysis, a two-compartment electrodialyzer setup was employed using cation-exchange membranes of the MK-40 (Russia) and EDC1R (China) types. The composition and structure of sodium tungstate, used as the starting reagents, were analyzed. Based on experiments conducted on a laboratory-scale unit with continuous circulation of the catholyte and anolyte, dependencies of various parameters on current density and process duration were established. Stepwise changes in the anolyte pH were recorded, indirectly confirming changes in the composition of the Na₂WO₄ solution, including the formation of polytungstates of variable composition and the production of H₂WO₄ via electrodialysis at pH < 2. The resulting tungstic acid solutions were also analyzed. The conducted studies on the processing of sodium tungstate solutions using electrodialysis made it possible to obtain alkaline solutions and tungstic acid at a current density of 500–1500 A/m², without the use of acid for neutralization. Yellow tungstic acid was obtained from the tungstic acid solution by evaporation.

Focuses on the processing of tungsten raw materials through various operations, including sintering, leaching, purification, and the production of technical tungstic acid. Modern research aims to enhance these processes, particularly the sintering of wolframite concentrates with alkali metal compounds and the leaching of concentrates and cakes. Experiments revealed that reactions between tungsten minerals and sodium carbonate from Akchatau ores commence at temperatures above 520–550 °C, intensifying between 750 and 850 °C. The concentrates were sintered at 750, 800, and 850 °C with a sodium carbonate excess coefficient of 1.05 to 1.2 to evaluate the effect on sodium tungstate extraction. Water leaching was conducted under a probabilistic–deterministic experimental design, analyzing five factors at four levels. Tungsten extraction was assessed based on solution density and the composition of the insoluble residue. Data processing established polynomial trends for tungsten trioxide extraction, and a material balance for sinter leaching was calculated from experiments using 100 g samples with a liquid-to-solid ratio of 2:1. The findings can be applied to improve tungsten processing technologies.

In this work the issue of processing of dross with preliminary separation of the metal part from the oxide one is reviewed. Based on a comparative analysis of the results of known works it is shown that this approach can be quite effective if a technology is developed for the separate processing of the oxide part to obtain a commercial product. The authors of this work proposed carrying out chlorinating roasting under oxidizing conditions with various chlorine-containing reagents as one of the effective ways of processing the oxide part of the dross. Based on the thermodynamic analysis of the reactions of interaction between the components of the oxide part of the dross and calcium and ammonium chlorides, the principal possibility of obtaining pure zinc oxide, suitable for use as mineral additives in animal feed has been shown. As a result of thermodynamic calculations of the reactions of interaction of impurity metals with calcium chloride and ammonium chloride, the values of Gibbs free energy and reaction rate constants were determined in the temperature range 973 and 1373 K. It has been established that under the conditions of roasting the oxide part of the dross with both calcium chloride and ammonium chloride, a high degree of sublimation of impurity metals from the dross in the form of their chlorides into dust is achieved. It has been shown that roasting the oxide part of the dross using ammonium chloride is more efficient than with calcium chloride.