PROCESS FOR OBTAINING MAGNESIUM BICARBONATE FROM DOLOMITE (CACO3 MGCO3) AND BRUCITE (MG(OH)2 CACO3) MINERALS AND BYPRODUCTS SUCH AS: PRECIPITATED CALCIUM CARBONATE (CACO3), PRECIPITATED MAGNESIUM CARBONATE (MAGNESITE MGC03) AND THE MIXTURE OF THE CAL

摘要

The present invention refers to the obtention of the following compounds resulting from non-metallic minerals, dolomite and brucite, both pertaining to the alkaline earth metal group, the process of the invention being different from that of the state-of-the art since the dolomite is a totally water-insoluble mineral and little soluble in weak acids such as carbonic acid, which is the other raw material used in the present process. When only using dolomite, the same must be totally calcined so as to be transformed from calcium carbonate and magnesium carbonate into their corresponding oxides and then into hydroxides by hydration, both the calcium hydroxide and the magnesium hydroxide being easily transformed into calcium carbonate and magnesium bicarbonate respectively, which is the main purpose of the present process. For performing the aforementioned reactions, it is required that the dolomite is calcined at a temperature of from about 1200°C to about 1300°C, and preferably at 1250° C, said temperature being useful for breaking the structure of the calcium carbonate since it forms part of the dolomite compound and acts as a heat refracting material. The calcinating process, referring to dolomite, may be modified by saving substantial calcinating power, wherein instead of performing the calcinating step at a temperature of from about 1200°C to about 1300°C, and preferably at 1250°C, it is performed at a temperature of from about 800°C to about 1000°C, and preferably at 900°C which is the temperature at which the magnesium carbonate is transformed into magnesium oxide, the carbon dioxide and the magnesium bicarbonate remain the same without suffering any modification in the molecular structure thereof. The aforesaid process promotes a substantial energy saving in the calcinations step. In addition, the use of carbon dioxide is required for re-precipitating calcium in calcium carbonate and releasing magnesium carbonate in a solution. Besides the obtention of calcium carbonate and magnesium bicarbonate, the process is useful for obtaining magnesite from the magnesium bicarbonate solution by means of bringing the liquid obtained from the reaction of the step 3 to a boiling point, magnesium being precipitated as magnesite (magnesium carbonate) in order to obtaining the total product of the step 3, calcium carbonate and magnesium carbonate being brought to a boiling point, the magnesium carbonate being precipitated over the calcium carbonate so as to form a light mouldable paste which has a high dielectric resistance as well as a high heat and noise resistance.