The demand for periclase and refractories made from magnesium oxide with a purity of 98-99% is rather high. It is possible to use Volgograd bischofite as a highly effective raw material for the production of magnesia of this purity.The Volgograd deposits of bischofite (MgCI2*6H20) constitute unique sources, both in terms of reserves, and also the quality of the magnesium chloride (95-98%). Moreover, it has a high concentration of bromine, 5-8 kg per m 3 of ore [i]. Note has been made of the need for all-round development of the bischofite with the production, primarily, of bromine and magnesia. The density of the liquhrs of the underground solution of bischofite is 1.29- The organization of large-tonnage production should be preceded by a range of investigational work in order to develop the technology and equipment specifications of the process.In this article we describe the results of obtaining, by the thermohydrolysis method, from Volgograd bischofite that has not been debrominized, magnesium oxide and periclase refractories based on it.The Combine received two cisterns of bischofite liquor (78. Magnesium, calcium, and iron were determine according to GOST 844-79, GOST 25423.4-80, and GOST 844-79, the alkaline elements --with the atomic-absorption method on the flame spectrophotometer "Saturn"; the sulfates were determined according to GOST 844-79, the chlorides using the Folgardt method [2], the silicon dioxide --according to GOST 24523.1-80. the residues insoluble in HCI (inorganic) according to GOST 844-79, and the boron by the volumetric method [3].
Natural and caustic magnesite should be beneficiated to a content of at least 98% MgO by chemical methods, including the hydrochloric acid method [1, 2].The East Institute of Refractories is planning a prototype unit with a capacity of 400 tons per annum using the acid method and natural magnesite with hydrolysis of magnesium chloride. This article gives the results of a study aimed at tightening up the parameters for beneficiating these two forms of magnesite with the acid method.The starting materials consisted of natural magnesites II and IV in the form of fractions --3 and --8 ram, and also ~milled (ballmill) material down to fractions --0.5 ram, including 40-50% fractions --0.063 ram, dolomite fractions --8 mm (the main mechanical impurity in the magnesite raw material) and magnesite caustic dust from the cyclones and electric filters. The dust from the cyclones in the form of fractions --0.5 mm contained 67% particles --0.063 mm and its specific surface was 2.3 m2/g; the dust with a specific surface of 4.7 m2/g from the electric filters contained 98% fractions --0.063 mm.One of the decisive processes in the acid benefieiation method for magnesite is the solution in the acid, and so we studied the kinetics of solution for rocks, minerals, and materials as a function of the grain sizes, the concentration, and temperature of acid. The rate of solution of magnesites was assessed from the weight and chemical composition of the insoluble part of the material being studied in a certain time interval (Table 1)o The magnesite was dissolved in hydrochloric acid of 12.5 and 20% concentration with 10 and 20% excess against the stoichiometric, and in this case the ratio of liquid and solid substance was for natural magnesite 8 : 1, and for caustic 14 : 1. Since the solution of natural magnesite occurs only during heating (hot-solution method) the acid temperature and solution temperatures were maintained at 80-85~The caustic magnesite was dissolved at 80-8 5~ and also at room temperature (cold-solution method). r, min r, rain The natural magnesite and the residual magnesium carbonate in the caustic dust were decomposed by the acid according to:MgCOa + 2HC1 8~176176 Y~gCI2 + H20 + CO21.The difference in the degrees of solution of magnesite in HC1 of different concentrations is zero; in 2 h in both cases about 85% of magnesite passes into solution. Natural magnesite in fractions --8 and --3 mm is dissolved at about the same rate. The kinetic curves for the solution ~ of natural magnesite and extraction e of oxides into solution are shown in Figs. 1 and 2. Figure 1 shows curves with three sections for the change in the solution rate of magnesite, fast (I5, slow (II), and weak (III) solubility.During the first 15 min in section I the rate of solution is 2.7, and in section IT 0.5%/min; later, the rate diminishes to 0.08%/rain (Bee Fig. lb).This change in the rate of solution of magnesite and other carbonate impurities in the raw material (dolomite, calcite, breunerite 5 is determined by the rate of the diffusion processes...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.