Magnesite beneficiation in heavy suspensions

Abstract

The magnesites of the Satkin deposits contain up to i5-20% dolomite, clay, schist, diabase, pyrites, and other impurities. Dolomite forms the largest proportion of these impurities.To produce a high-purity magnesite of constant composition, a department for magnesite beneficiation in heavy suspensions has been brought about* at the Magnezit Combine. Its output capacity is 1 million tons/yr (to be increased later to 3.5 million tons/yr).Use is made for the first time in Soviet practice of a two-stage two-section system for the separate beneficiation of the fine and coarse size fractions of ore (Fig. 1). The fine fractions (8-60 mm) are beneficiated in a conical separator and the coarse fractions (60-150 mm) in a cylinder-type separator with an elevator wheel. Every stage of beneficiation in heavy suspensions has its own regeneration cycle equipped with curved control screen, ~,BlVi-3 type electromagnetic separator, and divider for the discharge part of which is recycled as wash-water for the separation products.The magnesite to be beneficiated in heavy suspensions first undergoes primary crushing I (to size fraction smaller than 300 ram), then secondary crushing II (to size fraction smaller than 150 ram) in jaw crushers i and cone crushers 2 after which it is moved by conveyer belts 3 to the hopper 4 of the sorting unit III. Next, the material is separated into size fractions smaller than 8, 8-60, and 60-150 mm on GIT-52 type screens 5.The magnesite of size fraction smaller than 8 mm is transported by conveyer belts to ~he hopper of crushing--concentrating plant No. 2 (CCP-2) and then by overhead cableway (OHCW) to magnesite powder section No. 3 (MPS-3) for firing in rotary kilns.The magnesite of fractions 8-60 and 60-150 mm is transported by conveyer belts to the silo 6 of the hoppers of the storage yard IV and from there to the department of beneficiation in heavy suspensions V. To begin with, the fraction smaller than 5 mm is washed out of the material with clean water on screens 7 of the GST-51type, after which that size fraction is conveyed to a two-spiral classifier 8 in which it is separated into sand and sludge.

Conditions of flotation of Satka deposit magnesite residue

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A method of concentration of Satka deposit magnesites in a heavy suspension has been developed by the Siberian Electric Steel Plant and by a flotation method by the plant together with the Ural Scientific-Research and Design Institute for Concentration and Mechanical Working of Minerals [i, 2].At present in the Magnesite Combine, which processes Satka ores, a section for concentration in heavy suspensions with a capacity of i million tons per year is in operation.A plant for development of the section specifies an increase in its capacity [3].The production plan for concentration includes screening into 150-60, 60-8, and 8-0 mm fractions and concentration of the first two fractions in heavy suspensions.The 8-0 mm residue is not concentrated.The yield of it is 20-25%* of the original ore and the calcium oxide content varies from 1.8 to 5.2% and that of silicon dioxide from 1.0 to 3.5%.At the Siberian Electric Steel Plant a study has been made of concentration of the residue by gravitation--flotation and flotation methods [4]. The highest quality concentrates were obtained by flotation.

A sample of residue of Satka magnesites taken at the Magnesite Combine in concentration of currently mined ore was investigated.

The primary minerals# of the sample are magnesite (84.5%) and dolomite (13%).

Calcite, talc, serpentine, quartz, carbon-containing compounds, sulfides, iron hydroxide, and magnetite are present in small quantities.

The magnesite has a light gray color and a microcyrstalline, fine to medium grain structure.

It is present in the form of 0.5-4.0 mm free grains (40%) and aggregates.

Both in the aggregates and in the magnesite grains there are observed inclusions of talc, serpentine, quartz, calcite, and carbon-containing substances from 0.004 to 0.i mm in size.

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