This article presents a study on the precipitation of copper from the cyanide leaching solutions used for gold–copper ores, both with and without the addition of a sulphidizer (Na₂S). Mathematical models were developed to summarize the effects of the pH, initial copper concentration, and Na₂S stoichiometric ratio on the precipitation process, using an experimental design based on a probabilistic–deterministic method. Varying the stoichiometric ratio of Na₂S has a minimal impact on the precipitation process. However, the presence of a sulphidizer is significant, as the precipitation process occurs at pH levels of 5 and below. The initial concentration of copper in the solution was identified as the most significant factor. At copper concentrations of 0.34% and 1.55% (pH = 3), the precipitation rates were 51.48% and 47.6%, respectively. This study also determined that the most effective method across the entire range of copper concentrations in the solution was the precipitation of copper in the form of copper cyanide hydrate (CuCN∙nH₂O) without the addition of Na₂S. At copper concentrations of 0.34% and 1.55% (pH = 3), the precipitation rates were 86.47% and 85%, respectively. The pH level was the most significant factor influencing this process, as copper deposition without Na₂S did not occur at a pH of 5. The obtained models allow us to accurately predict the influence of factors on the deposition process. Aided by the mathematical model of precipitation (without Na₂S), we selected the conditions for an enlarged experiment using 20 L of solution (Cu = 0.34%, pH = 3.2), which showed the high efficiency of the method. The calculated recovery amounted to 86%, where practical recovery was 87.2%, and divergence was ≥1.2%.

In this study, we investigate the potential of using acrylonitrile–butadiene–styrene flame-retardant (ABS FR) plastic obtained from electronic waste to create a new composite material through the addition of fly ash microspheres obtained from the combustion of thermal coal at Ekibastuzskaya GRES 1, with the resulting material being suitable for the manufacturing of housings and other elements of electronic equipment. For this purpose, five composite compositions with microsphere/plastic ratios of 10/90, 20/80, 30/70, 40/60, and 50/50 were developed, which were then processed in an extruder at 250 °C to obtain test specimens. The thermal and mechanical properties of the specimens were compared with a control sample developed using ABS FR plastic from electronic waste without the addition of microspheres. The obtained materials, up to a microsphere/plastic ratio of 20/80, demonstrate increased mechanical properties and thermal stability with a simultaneous decrease in material density, while a further increase in the concentration of microspheres leads to a gradual decrease in mechanical properties. These properties make it possible to use the obtained composite for producing housings and other elements of electronic equipment.

This article discusses possible approaches to recycling electronic waste, with a focus on the main components of a personal computer (PC) system unit (SU). The study makes a significant contribution to solving the problem of natural resource depletion and environmental pollution. The article evaluates the possibility of commercial extraction of valuable metals without the use of reagents, complex processes, and equipment, as well as the utilization of plastic electronic waste (e-waste) in the construction industry. The proposed scheme for recycling the main components of printed circuit boards (PCBs) allows aluminum and copper alloys to be extracted from metal elements. Recycled PCBs provide raw materials containing more than 35.5% copper and other valuable metals. The plastic used in the production of control printed circuit boards is proposed to be used as an additive for construction concrete. When 40–50% of plastic is added to the mass of sand, concrete samples of grades M250–M200 can be obtained. And with a plastic content of 10–20% of the sand mass, concrete grades M350–M300 are obtained, which can be used for foundations and monolithic construction of low-rise buildings. A preliminary assessment of the toxicity of concrete has shown that it is safe. A preliminary assessment of the concrete’s toxicity revealed that it is safe. An initial evaluation of the commercial feasibility of processing the main components of the SU PC revealed the possibility of obtaining funds of approximately $3183.7 per 1000 SUs, without the use of complex processing schemes. The use of secondary metals will significantly reduce CO₂ emissions. The need for this study is driven by the high relevance of the issue of electronic waste disposal. Despite numerous studies in this area, the amount of waste worldwide is growing, which indicates the low effectiveness of existing methods.

This paper examines energy-efficient and environmentally friendly methods of processing technogenic gold-bearing raw materials. The main focus is on studying the kinetics of the thiourea leaching process after the preliminary oxidative roasting of gold-bearing materials obtained from technogenic waste from a gold extraction plant. This study compares traditional roasting in an electric furnace with roasting in a chemical reactor with microwave treatment. Preliminary oxidative microwave roasting was found to achieve a higher thiourea leaching reaction rate due to better exposure of refractory gold. Compared to traditional oxidative heating, roasting in a microwave-assisted chemical reactor reduces processing time and energy consumption while improving the degree of preparation of the raw materials for subsequent gold leaching and increasing gold recovery by 17.8%. This reduction in activation energy is due to preliminary oxidative roasting with microwave treatment (P 1.1 kW, frequency 2.45 GHz, 700 °C for 10 min), which results in an energy reduction of 14.716 kJ/mol versus 22.630 kJ/mol for traditional oxidative roasting in an electric furnace (750 °C for 60 min).

The processing of gold-copper ores with high copper and gold content embedded in sulfide minerals using cyanide solutions is associated with a number of difficulties. Copper, when reacting with cyanide, causes its increased consumption, and the embedding of gold in sulfide minerals causes gold losses with tailings. Therefore, selecting the optimal leaching conditions is necessary for the rational use of reagents, which leads to a reduction in the cost of hydrometallurgical processes for cyanide leaching of gold-copper ores and a reduction in environmental risks. The paper investigates the possibility of processing gold-copper ore with a high copper content and gold incorporated into sulfide minerals (pyrite, chalcopyrite). The aim of the work is to establish the optimal parameters for cyanide leaching by conducting tests in bottle agitators. As a result of the experiments, it was found that as the degree of ore grinding increases, gold extraction increases and cyanide consumption decreases slightly. The addition of coal during leaching significantly increases gold recovery, up to 7 %. It was noted that high sodium cyanide consumption cannot be reduced without a significant decrease in gold recovery. Au ≈ 20 % reduction in sodium cyanide consumption also reduces gold recovery by ≈ 20 %. A laboratory-industrial experiment showed that after 16 hours of ore leaching, 85.8% of the gold is transferred into solution, and after 18 hours, 86.7 %. Further prolongation of the process does not increase the gold recovery rate. Keywords: gold-copper ore, optimal parameters, cyanide leaching, gold, copper.

The article discusses the current state-of-the-art in the tin industry and the prospects of the Republic of Kazakhstan. The evaluation is performed in terms of the development of domestic tin production for the growing global demand and the development of the domestic high-tech industry. The study includes the main domestic sources of the raw material base of the tin, which includes mineral raw materials, anthropogenic and secondary waste. Since the most important for the contemporary tin industry are mineral raw materials, the possibility of complex processing of ore from the Syrymbet deposit was studied. Based on the results of the studies performed, it was found that the mineral tin-containing raw materials of the Syrymbet deposit, in addition to cassiterite, also contain acid-soluble tin-containing minerals (stannin, etc.). At the stage of gravity concentration, the most efficient extraction performance of tin into concentrate was found for the gravity separator – amounting to 34.2%. At the leaching stage, the most efficient extraction of tin (1,543 μg/L) showed an aqueous solution of sulfuric acid with a concentration of 100 g/L, at a temperature of 45 °C.