METHOD OF COMPLEX PROCESSING NATURAL AND/OR SYNTHETIC CHALK, OBTAINING CHEMICALLY PURE CHALK AND AMMONIUM NITRATE LIME Russian patent published in 2009 - IPC C01F11/18 

FIELD: chemistry.

SUBSTANCE: present invention pertains to the method of processing natural or synthetic chalk, obtaining chemically pure chalk, which can be used in different industries, as well as to the method of obtaining ammonium nitrate lime using wastes from this production. The method involves decomposition of natural and/or synthetic chalk using nitric acid, adding chalk to the obtained suspension, separation of undissolved residue by filtration, subsequent conversion of calcium nitrate solution by ammonium carbonate, filtration of the obtained suspension with separation of chalk and processing of the ammonium nitrate separated from chalk, to ammonium nitrate lime, by mixing with the separated undissolved residue and raw chalk. The product is then granulated. For decomposition of chalk, nitric acid is taken in stoichiometrical quantity of 80-95% for 30-50 minutes, in ratio T:L= 1:2.5-3.5. Chalk is added to the decomposition suspension in quantity, sufficient for attaining pH=5.5-6.0. The chalk obtained after conversion is extracted from the process as a finished product. Ammonium nitrate solution is evaporated to 70-95% concentration ammonium nitrate and taken to the ammonium nitrate lime production process. A 47-54% ammonium carbonate solution is used in the conversion of calcium nitrate, in quantity sufficient for attaining pH=7.5-8.5.

EFFECT: obtaining high quality chalk with simplification of the technological process and cutting on energy expenditure on the ammonium nitrate lime production stage.

2 cl, 1 tbl, 1 ex