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.

The essence of the industrial hydrochloric acid conversion of natural magnesium-containing raw material into high-quality MgO is well known. The original material is treated in HCI, and then the magnesium chloride solution so formed is freed of impurities and hydrolyzed by heating. The so-called hydrolytic MgO obtained in this way is freed from the remaining impurities and the oxide converted to magnesium hydroxide. Next, the magnesium hydroxide is briquetted. The briquettes are sintered or fused and then milled down to obtain a powder of the required grain composition [1][2][3][4][5].One feature of the HCI treatment of magnesite is the possibility of using the main mass of HCI in a closed cycle. Regeneration of the HCI takes place during the thermal hydrolysis of the purified solution of magnesium chloride. In accordance with the plan drawn up by the Eastern Institute of Refractories and the Ukrainian Institute of Chemistry, a pilot plant has been built at the Magnesite Combine; this has been mastered and is used for the hydrochloric acid treatment of magnesite; the annual productivity of the equipment is 400 tons.In [6] some features of the process of dissolution of natural and caustic magnesite in HCI and the sintering of the beneficiated product [7] have been considered. The present article pays particular attention to the apparatus-process character and considers in more detail the hydrolysis of magnesium chloride.The outline of the process of this stage of beneficiation of magnesite on the plant is shown in Fig. i. The chloride solution at a concentration of ~150 g/liter (relative to MgCI2) after being freed from impurity Fe, AI, and Si comes from the preparation and solution-purifying stage to the recuperator for preliminary concentration. The concentrate formed (concentration of MgCI2 = 300-350 g/liter) is sent from the collector tank to the atomizing spray reactor, in which the thermal hydrolysis of the MgCI= takes place in accordance with the reactions Some of the solid product settles in the conical bottom of the reactor, and the rest is removed as a gas product to the cyclone from where it is returned to the atomizing reactor via the overflow. The off-loading of the hydrolytic MgCI2 is done from the bottom. As the heat-carrying reagent we use the combustion products of natural gas. The gaseous reaction products free of solid phase and at a temperature of 250-300~ reach the recuperator where, after giving out some of the heat in the evaporation of the initial MgCI2 solution, are cooled to 90~The gas then goes to the absorption column, where the HCI is absorbed and hydrochloric acid is formed. The scrubber column and the spray collector are used as further means of purifying the gas products of the reaction by removing the HC1. The whole system is operated under low pressure which is created by the vacuum pump. The gas products with the dust and HCI removed are dispersed into the outside atmosphere. The HCI obtained is returned to the preparation stage for the purification of the solution, while the hyd...

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