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.

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 article is devoted to development of a brand new approach to solution of the issue related to development of efficient technologies aimed at processing of especially refractory and hard to concentrate ledge gold ore types. A new technology of such gold ore Reducing Pyrometallurgical Selection (RPS Process) utilising the direct smelting process avoiding its concentration has been developed for the purpose. Utilisation of high temperatures and liquid phase melting processes allows actually complete processing of refractory gold ores irrespective of the mostly complex resistance to processing types and with simultaneous and efficient performance of the following four process operations: a complete removal of any waste rock in the form of melted slag containing gold not exceeding 0.1-0.3 g/t; a complete transfer into the gas phase and removal of arsenic and other harmful admixtures with off gases; complete combustion of all the ore carbon containing matter types obtaining additional heat for smelting and reducing gas phase; an actually complete transfer of any precious metals into a sulphide melt, collector matte, with gold recovery of 95-99%, which yield will amount about 10% of the ledge gold ore weight. Thus, the developed technology ensures a ten-fold decrease of processed ore amounts in the process head. The RPS Process has been developed and tested in laboratories and under workshop conditions on the basis of direct electric smelting of hard to concentrate and refractory ledge gold ore from a number of deposits of Southern, Central and Eastern Kazakhstan. Such tests of the RPS Process revealed the possibility to increase throughout gold recovery by 10-15% as compared with currently achieved in dices in case of especially refractory ledge ore processing.

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