RATIONAL PROCESSING OF REFRACTORY COPPER-BEARING ORES

The paper presents the results obtained when studying material compositions of four samples of refractory copper-bearing ores from the Uzelga deposit along with technological solutions to improve their processing parameters. The refractoriness of ores is associated with a thin dissemination (up to a micron size) and close intergrowth of ore and rock minerals. Ferrous sulfides are represented by a wide range of minerals: pyrite, marcasite and their variety melnikovite, arsenic pyrite and arsenopyrite; sooty melnikovite has a higher flotation activity. The reduction of iron sulfides from 89 to 29 % is followed by a proportional increase of easy-floatable rock minerals to 45 % and clay to 9 %. These properties make these sulfides difficult to process (float) and maintain ore refractoriness. The content of copper sulfides in ore samples varies from 3,32 to 7,29 %; the relative fraction of copper sulfide in a form of tennantite in different deposit samples varies from 29 to 93 %. Copper is also present as chalcopyrite and bornite. The best flotation activity of tennantite can be seen in neutral and weak acid media in contrast with standard flotation mode for chalcopyrite and bornite with butyl xanthate in a high-alkaline calcareous medium. Free grains of copper minerals can be selectively extracted into the intermediate flotation copper concentrates when grinding maximum 60 % of the –71-μm class. The technology of flotation in a low-alkaline medium is developed for refractory copper-bearing ores with variable tennantite content using the M-TF selective sulfhydryl collector in intermediate copper flotations and copper concentrate upgrading cycle; aeration used to suppress melnikovite flotation activity makes it possible to achieve 80 % copper recovery into conditioned copper concentrate. Bornite, tennantite, chalcopyrite and sphalerite disseminated in pyrite make it rational to obtain copper-pyrite, copper-zinc-pyrite products with their yield up to 12 % for pyroand hydrometallurgical processing.

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