Preparation of Refractory Materials from Karelian Chromite Raw Material and Physicochemical Processes During Service
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Vol. 61, No. 3, September, 2020
RAW MATERIALS PREPARATION OF REFRACTORY MATERIALS FROM KARELIAN CHROMITE RAW MATERIAL AND PHYSICOCHEMICAL PROCESSES DURING SERVICE A. S. Zavertkin1,2 Translated from Novye Ogneupory, No. 5, pp. 12 – 15, May, 2020.
Original article submitted January 20, 2020. The mineral and chemical compositions of the chromite raw materials of the Karelia-Kola region are studied, and physical and chemical processes for producing refractory materials from chromite concentrate are established. The phases and structure formed during drying, firing, and service are determined. The dependence of some refractory properties on their material, grain, and phase compositions is established. Keywords: chromite rocks, chromium oxide, enrichment, filler, refractory material.
mately 100°C, which facilitates melting of alloy steels, and improving a furnace campaign.
INTRODUCTION An intentional search for chromium ore on an industrial scale in the Karelia-Kola region has only started recently. The location of chromite ores of Karelia (Burakov Aganozer) Kola peninsula (Greater Varak, Sopchezer deposit) are comparable with respect to structure and metallogeny to the well-known ore-bearing massifs of Kemi (Finland), Bushveld (RSA), and Steelworcester (USA) [1]. Chrome-spinelids are the main ore-bearing mineral of these deposits and are classified as an iron variety containing 45 – 52% Cr2O3. Prediction of the resources of these ores in the Karelia-Kola region is estimated in several hundreds of millions of tons. Chromite ores are used for preparing chrome-magnesite and magnesite-chromite refractories, the main ones of which periclase and chrome spinelids. These refractories are used extensively in view of replacement of dinas in arches and other elements of a lining of steel-smelting furnace. The arches of electric melting furnaces, made from magnesite-chromite, compared with dinas permit an increase in temperature within the melting space by approxi1 2
STATE OF THE QUESTION The name chromite may concern both the mineral composition (Mg,Fe)O·(Cr,Al)2O3, and also rock containing more than 80% this mineral. This formula also corresponds to minerals of chrome-picotite and chrome-spinelid. Chrome-spinelid is encountered almost exclusively in magmatic ultra-basic rocks in the form of disseminations and complex accumulations. Harmful impurities reducing chromite refractoriness concern serpentine (magnesium hydrosilicate), olivine, and chromium-containing chlorites. Chlorite or magnesium hydroaluminosilicate impurities are present in rock together with serpentine. Ores with a Cr2O3 content not less than 33% are suitable in order to produce refractories; ores with a lower Cr2O3 content are unsuitable for refractory production [2]. The most valuable deposits of Russia are the Don in the western flank of the southern part of Urals and Saranov in the west Urals. The chrome-spinelid part of the ore of these deposits is represented by chrome-picotite and the non-ore part is represented by a mixture of serpentine and chlorite.
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