HYDROMAGNESITE WASTE-ROCK IN MAGNESIA CEMENT TECHNOLOGY
The research is relevant due to the need for the integrated use of magnesium materials, including mining waste. During the extraction of magnesia raw materials, as a refractory and strategic material, in some deposits the accompanying material is hydromagnesite rock, which is not used in classical magnesia technology. Simultaneously, it has characteristics that make it possible to obtain important products: fire retardants for various materials, a porous component in fire-resistant coatings, a feedstock for creating waterproof magnesia binders.The aim of the research is to determine the possibility and conditions of using the hydromagnesia formation of the Khalilovskoe field as a feedstock for obtaining water solution of magnesium bicarbonate - a mixing liquid of a waterproof magnesia binder.Materials: hydromagnesite rock accompanying magnesite of the cryptocrystalline structure of the Khalilovskoe deposit, Orenburg region. The studied rock consists of hydrocarbonate minerals: hydromagnesite, deepingite, nesvigonite, as well as admixture of clinochrysotile. The bicarbonate composition does not allow its use for molded fired magnesia products.Methods. The method of thermal activation of hydromagnesite rock makes it possible to produce a highly reactive defect structure; obtaining a solution of magnesium bicarbonate by artificial carbonization of a suspension of activated hydromagnesite material; thermal research methods - differential scanning calorimetry, thermogravimetry; X-ray phase analysis; titrometric method for determining the concentration of bicarbonate ions.Results. The possibility of using hydromagnesite formation to obtain water solution of magnesium bicarbonate with the bicarbonate ionconcentration of up to 38 g/l was determined; the efficiency of heat treatment of hydromagnesites in the temperature range of 300-375 °C was established, that allows obtaining a highly defective product xMgCO3∙yMg(OH)2; thermal activation of hydromagnesites increases the efficiency of the transition of bicarbonate ions and magnesium cations into solution in the presence of CO2 at the low pressure of 0,2 MPa of the carbonization process; water solution of magnesium bicarbonate with high concentration of bicarbonate ions obtained at the low pressure of CO2 gas will make it possible to create hydraulic magnesia binders with high water resistance.