Pyro-metallurgy of copper production is characterized by the output of copper slag, which is regarded as a kind of solid waste. Moreover, this slag is identified as hazardous because it contains impurities, like Pb, As, and Cu. Obtaining dump slags in autogenous processes does not always meet the requirements of effective technologies, most often slags contain more than 1.0% of copper and need to be depleted. This work is presented a brief analysis of existing technologies used for copper slag depletion. The analysis of the existing technologies for the depletion of autogenous smelting dump slags showed that the most promising option seems to be the depletion of copper slags in one PV unit since by improving the process itself, by changing the unit design, it is possible to achieve technologically complete production of matte and dump slag with low copper content. There were proposed two technologies of improvement: electro-heating of slag siphon using the graphite electrodes and depletion process in two-zone PV furnace.

The growing environmental impact of copper production necessitates innovative approaches for optimizing metallurgical processes and minimizing waste. This study addresses this challenge by leveraging advanced machine learning (ML) techniques to enhance the efficiency of pyrometallurgical operations such as slag optimization, composition prediction, and waste minimization. Using a combination of real-world and synthetic data, we developed models capable of both forward prediction, estimating slag and matte compositions from ore characteristics, and backward prediction, inferring ore compositions from output characteristics. Five ML algorithms were evaluated, with Gradient Boosting and Support Vector Regression demonstrating superior performance in capturing complex, non-linear relationships. Forward prediction achieved near-perfect accuracy, while backward prediction highlighted the inherent complexity of inverse modeling. This backward-driven strategy proposed in this research aims to determine optimal ore compositions to achieve desired outputs, reducing waste and energy consumption. By integrating ML models with a systematic hyperparameter optimization approach, this work advances the potential for sustainable and precise metallurgical processes. While challenges remain in refining backward predictions, the findings demonstrate the transformative potential of data-driven strategies in industrial metallurgy, paving the way for environmentally sustainable and economically efficient copper production practices.

The objects of the study were converter slags from the Balkhash copper plant in their initial state and after heat treatment. Using mineralogical and X-ray phase analysis, scanning electron microscopy (SEM), and electron probe microanalysis (EPMA), it was found that the initial converter slag and its thermally treated samples have identical matrices with almost complete coincidence in mineral and phase compositions. The distinguishing feature is the quantitative ratio of mineral components in the slag mass. Almost all of the iron is oxidized and present in the form of fayalite, magnetite, and magnetite, with other elements (silicon, copper, zinc, and aluminum) incorporated into its lattice. The structure of all slag samples indicates an association of sulfur exclusively with copper. Copper in the slags was identified in both metallic and sulfide forms. Slow cooling of the converter slag after its remelting contributes to the reduction in the sulfide–metal suspension in the volume of the melt and its coarsening. During slow cooling, structural changes occur not only in the main oxide part of the slag but also in the polymetallic globules.

The article describes the effect of the fluxing ability (FA) of ores used as a flux on slag formation and copper losses. In Kazakhstan, at the Balkhash copper smelting plant (BCSP), currently used fluxes have a very low SiO₂ content—about 62%—whereas the Al₂O₃ content is 12%. Its fluxing ability (FA) was estimated, and it was shown that currently used silica fluxes have an exceedingly low FA. Only half of the fluxes participate in the slag formation. To obtain slags with a low magnetite concentration, a considerable surplus of flux must be added, which will result in a sharp reduction in its melt temperature, increased slag output, and therefore copper losses. The slag structure was studied by means of scanning electron microscopy and electron probe microanalysis (EPMA). To determine one of the primary causes of flux ores’ low FA, it is necessary to use the microstructural pattern of experimental samples.

Preliminary experiments have shown that the solution to the environmental problem of recycling copper-electrolyte smelting slags is by sulfidization followed by leaching and subsequent separation of selenium, tellurium, arsenic, and antimony from the solution. The first operation of this technology, which provides high selectivity, is sintering. The results obtained indicate the formation of metal thiosalts during sintering in the presence of sodium sulfate and carbonate and a reducing agent at a temperature of 800 0C. An increase in temperature leads to the melting of individual components of the charge and a slowdown in the process of sulfidization of slag components. At lower temperatures, a decrease in the activity of the charge components is observed. The optimal addition of Na2SO4 was 27 % of the slag weight, and Na2CO3 - 8.5 % of the slag weight. Reducing agent consumption is 27 % of the slag weight, sintering time is 2 hours. The optimal parameters for leaching the resulting cakes are temperature 90 0C, L:S ratio = 3:1, leaching duration 2 hours, and sodium sulfide concentration 2 mol/l. The best results for cake melting from cake leaching are temperature 1200 0C, heating rate 10 0C/min, and holding time 30 minutes. Charge composition: cake, 30 % soda ash by weight of cake, 11 % activated carbon. During the smelting, a metallized phase was obtained, consisting mainly of lead (90-91 %), and slag was obtained with a residual content of lead and copper of no more than 0.5 %.

The study object was slag from the Balkhash copper smelter, obtained by re-melting anode mud containing nonferrous metals. The process flow for processing these slags includes sintering with Na₂SO₄, Na₂CO₃, and coal, followed by soda-alkaline leaching of the sinter and extraction of metals from the solution into marketable products. Since sintering is the main operation providing high selectivity, the composition of the products of this process was studied. The main transformations during sintering were determined, and the optimal parameters were identified. The structures of slags and sintered materials obtained during the experiments were studied by electron-probe microanalysis. Sintering was performed at 600–800 °C. The best results for sulphidization of slag components were obtained at 800 °C; a further increase in temperature leads to the smelting of sinter particles and slows down sulphidization. The optimal quantities of additives, based on the weight of the slag, are Na₂SO₄—45%, Na₂CO₃—15%, and reducing agent—41%, with a sintering time of 2 h. These conditions enable the sulphidization of non-ferrous metals in the slag to the entire depth of the polymetallic globules. The distinct concentration of harmful impurities (Ni, As, and Sb) was observed in the fine structure of the polymetallic globules.