Saint Petersburg State Mining University (Russia):

Dubovikov O. A., Associate Professor

Andreev Ye. Ye., Associate Professor, opiopi@bk.ru

Nikolaeva N. V., Assistant

One of alternatives in bauxites chemical processing is the method of preroasted bauxite desiliconizing by means of alkaline solution. In spite of high energy costs, roasting permits to condition bauxite raw materials with respect to a number of detrimental-to-processing impurities, such as organic matter, sulfide sulfur, carbonates. By way of example of high-sideritized Kazakhstan bauxites, the positive role of roasting in processing this type of bauxites is shown. The obtained results permitted to presume, that preroasting at temperatures over 550 °С will provide for processing this type of bauxites by Bayer's method with improved metallurgical results. As an alternative, the data is presented with regard to detrimental effect of siderite being eliminated through its removal into magnetic fraction, to be processed by Bayer's method with preroasting. The technology included feed ore grinding on mother liquor, mills pulp separation in strong magnetic field and non-magnetic fraction processing by sequential Bayer-roasting method. According to the proposed flow sheet, it is recommended to process magnetic fraction either by a separate circuit or by means of roasting together with red mud. The studies conducted with the view to develop a technology to process bauxites with increased content of carbonates using magnetic separation techniques, demonstrated a possibility in principle for bauxite quality improvement through removal of one of its most detrimental impurity - siderite. Effects of various factors, determining the separation process of minerals with magnetic properties, first of all, siderite, were studied under laboratory conditions.

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