Satbayev University, Almaty, Kazakhstan:

N. K. Dosmukhamedov, Associated Professor
Е. Е. Zholdasbay, Research Fellow

National University of Science and Technology MISiS, Moscow, Russia

A. N. Fedorov, Professor, e-mail: fedorov_a_n@mail.ru

This paper describes an experimental study that aimed to find a way to deplete high-copper slags resultant from autogenous smelting. The study focused on arsenic and its behaviour during high-temperature reduction of slags. The authors did a comparative analysis of the well-known research papers to show that the coal reduction of slags would not help produce a copper alloy in a condensed phase. A high concentration of arsenic in the alloy impedes its further application. The paper examines the problem of two-stage depletion of high-copper slags in a severely reducing environment with natural gas and coal. It is shown that when natural gas is used as a reducing agent for slag, a high recovery of arsenic into dust can be reached even during the first stage. It is demonstrated that the consumption of natural gas exceeding by 30% the stoichiometric consumption necessary to reduce As2O5 to the volatile compound of As₂O₃ helps completely remove arsenic from the slag turning it into dust. Due to a combined use of natural gas and coal during the second stage, a high degree of selective recovery of non-ferrous metals into target products can be reached: copper into copper-iron alloy, and lead and zinc into dust. It was established that the optimum consumption of natural gas that equates to the minimum concentration of metals in the slag, %: 0.25 Cu; 0.06 Pb; 0.18 Zn, corresponds to the consumption of natural gas that by 30% exceeds the consumption that would be theoretically necessary for reducing their oxides. This would ensure the minimum concentration of iron in the alloy (0.08%) and a low concentration of the solid deoxidizer (i. e. coal). On the basis of experimental data and the balance sheet of materials drawn up for each experiment, the authors calculated how the non-ferrous metals and arsenic would distribute between the products of the two-stage deoxidizing depletion of slag with natural gas in the presence of coal as a function of the amount of natural gas consumed. The proposed method of the two-stage deoxidizing depletion of slag with natural gas in the presence of coal would not require a lot of investment and can be easily integrated with the current copper and lead production processes. Without much effort or great cost, the resultant products can be used to produce a broad range of commodities with a high added value.

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