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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]