The article presents the results of oxidative leaching of lead sludge from copper production in order to extract rhenium into solution. The optimum regimes for product leaching man-made product in the presence of sodium peroxocarbonate Na₂CO₃1.5H₂O₂ has been established: Experimental work was carried out under the following conditions: oxidant consumption 5 by weight of the raw material, leaching temperature 70C, duration 3060minutes, stirring speed 200rpm, and the ratio of liquid to solid S:L=1:3. The degree of extraction of rhenium into the solution is 9597, and the content reaches 500520mg/L Re.

In this study, we investigate the reduction smelting of antimony concentrate, where sodium antimonate is the primary antimony-bearing component, in alkaline melts. This study aims to reduce the carbon footprint of metallic antimony production. It is shown that traditional carbon reduction is accompanied by significant formation of carbon-containing gases and sodium losses due to volatilization. Based on thermodynamic analysis and experimental investigations, carbon monoxide is established as the key active gaseous reducing agent for antimonate compounds, predominantly operating in the temperature range of approximately 320–900 °C, which corresponds to the stages of coke oxidation and sodium antimonate decomposition. The authors propose introducing sodium hydroxide into the charge to form an alkaline melt with a lowered melting point when mixed with the antimony concentrate, ensuring the sequestration of carbon dioxide through the formation of sodium carbonate. Experiments confirmed the possibility of chemically fixing up to 75.5% of CO₂ into the slag phase at the laboratory stage and up to 87% of CO₂ during pilot tests of reduction smelting under a flux layer. Crude metal with an antimony content of 94–96.2% Sb was obtained, while coke consumption was reduced by 16–20%. The proposed approach ensures a simultaneous increase in the degree of antimony recovery, the utilization of carbon-containing gases, and the formation of a stable eutectic slag melt. This allows the process to be considered an element of carbon-neutral pyrometallurgical technology for processing antimony concentrates.

Lead cake forms from dust as a result of the gas cleaning process during copper smelting. The objective of this study was to develop equipment and technology for a continuous hydrometallurgical method for extracting osmium from the lead cake. In this method, leaching is carried out using an aqueous solution of hydrogen peroxide and sulfuric acid. During the leaching, rhenium is converted into an acidic solution from which rhenium can be easily extracted into a marketable product. Osmium is predominantly converted into a solution, the processing of which, including the extraction of osmium into a marketable product, will be published later. A unit for leaching osmium–rhenium-containing cake with continuous loading for leaching, continuous feeding of leaching solutions, and continuous discharge of the leaching slurry was created. Using the simplex experimental design method, the dependence of osmium recovery on the consumption rates of hydrogen peroxide and sulfuric acid and the leaching duration was studied. Near-optimal leaching conditions were as follows: 68–70 mL of 30% hydrogen peroxide and 7 mL of concentrated sulfuric acid per 100 g of cake, 55 min of leaching, and a specific column throughput of 100 g of cake per 55 min. Nine experiments achieved 96.5% osmium recovery.

The processing of lead cakes containing osmium and rhenium is complicated by the significant variability in their elemental and phase compositions. The aim of this study was to determine the effects of lead cake composition on acid consumption and the recovery of Os and Re during oxidative leaching in a continuous-flow reactor. The leaching of 15 industrial cakes derived from copper production—containing 440–4260 g/t Re and 23–63 g/t Os—was investigated in a sulfuric acid medium, using sodium hypochlorite as the oxidizing agent. The experimental results showed that increasing contents of PbCO₃, PbO, and metallic Pb in the cake reduce Os and Re recovery at a fixed reagent dosage. It is established that variations in H₂SO₄ consumption are primarily driven by the cake’s phase composition; in particular, the acid is consumed through reactions with acid-neutralizing matrix components (PbCO₃ and PbO), thereby altering the effective pulp acidity and oxidative leaching conditions. Thermodynamic modeling indicated that pH changes primarily affect the chemical state of matrix components, whereas Os and Re remain predominantly in the forms OsO₄(aq) and ReO₄⁻, respectively. Under near-optimal conditions, recoveries of up to 95–96% for Os and 99–100% for Re were achieved. The kinetic study results demonstrated a faster extraction rate for Re compared with Os. In summary, the results show that the phase composition of the cake is a key parameter influencing acid and oxidant consumption; furthermore, adjusting the reagent regime based on the composition of industrial lead cakes enhances the stability and efficiency of Os and Re recovery.