JSC Russian Copper Company, Ekaterinburg, Russia:

Yu. A. Korol, Vice-President, e-mail: tsvetmet@rudmet.ru

Ural Federal University named after the first President of Russia B. N. Eltsin, Ekaterinburg, Russia:
S. S. Naboychenko, Head of the Department of Metallurgy of Non-ferrous Metals

The depletion of converter slags by the phase mixing method is based on the exchange reactions between oxides of copper, nickel and cobalt and iron mass. For nickel matte, the presence of metallic iron in the matte is an additional and significant factor leading to the improvement of the efficiency of the depletion process. As the slag and matte phases interact, the non-ferrous metal oxides are reduced, then sulphided and converted to a melt mass. The iron is oxidized and slagged with quartz to form an additional amount of slag, which is removed from the converter after pre-settling. In this connection, the melt of the depletion converter is enriched with nickel, cobalt and copper, while reducing the iron content. This circumstance leads to a decrease in the reduction and sulphidation of metals and an increase in their content in the treated slag. The slag becomes reversible. To prevent metal losses, new batches of matte are added to the converters or a second stage of depletion is organized in a similar way. This leads to the use of additional equipment — set converters and nickel matte cooking, or redistribution of nickel flows between the nickel matte and autoclave mass. In order to improve the efficiency of the method of impoverishment by phase mixing in converters, it is proposed to use tuyeres with a protective shell from natural gas. Practical implementation of this approach allowed not only to prolong the campaign of the depletion converter due to a more even wear of the refractory lining, but also to slow the interaction of oxygen with iron at the moment of mixing the slag and matte phases. This circumstance prolonged the reducing and sulphiding abilities of the melt. With the same initial quantity of matte, it became possible to increase the processing of slag with the provision of specified contents of recoverable metals in it. The introduction of this method of depletion makes it possible to reduce the number of circulating slags and the volume of unfinished pyrometallurgical production. An additional effect of depletion of slags under the conditions under consideration was noted only for cobalt and nickel. The share of copper in nickel slags did not decrease due to its low content and other distribution mechanism between the melt mass and slag. The high concentration of dissolved sulphide copper and its mechanical losses indicate the efficiency of copper recovery from slags with good mixing, sufficient subsequent sedimentation, lower viscosity and an increase in the temperature of the slag melt.

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