METHOD OF PRODUCTION OF CHEMICALLY PRECIPITATED CHALK Russian patent published in 2000 - IPC

FIELD: inorganic materials. SUBSTANCE: invention relates to methods of production of chemically precipitated chalk that can be used in food, perfume-cosmetic, medicinal, chemical and other branches of industry. Method of production of chemically precipitated chalk involves slaking limestone with water at 80-90 C, carbonization of milk of lime to yield chalk suspension, separation and drying the end product. Limestone slaking with water is carried out up to formation of 10-14% suspension of milk of lime and before carbonization milk of lime suspension is subjected for treatment. Carbonization is carried out with gas of limestone-roasting furnaces with carbon dioxide volume part 20%, not less. Chalk product is separated under vacuum 80-90 Pa and drying up to attainment of bulk density value 0.25-0.35 g/cm³, not above. Optimal conditions of the process are the following: for slaking technological lumpy limestone with mass part of sum of active calcium oxide and magnesium oxide (as measured for calcium oxide) 70%, not less, is used; milk of lime suspension is subjected for treatment up to attainment of density value 1.06-1.11 g/cm³ at 20 C; gas of limestone-roasting furnaces is purified preliminary in dust-collecting chamber, cyclone and water countercurrent settlers; product is dried in loop-shaped driers using natural gas combustion products as a heat carrier; after drying product is ground. EFFECT: decreased energy consumption, enhanced degree of chalk whiteness. 7 cl