METHOD OF PRODUCING MIXED ALUMINIUM DIHYDROXOCHLORIDE COAGULANT AND SILICIC ACID COAGULANT Russian patent published in 2012 - IPC C08J9/28 

FIELD: chemistry.

SUBSTANCE: invention relates to chemical industry and nonferrous metallurgy. The method involves preliminary mixing of kaolin clay with sodium silicate in amount of 1-2% of the weight of the kaolin clay. The mixture is then rolled into granules which are then calcined at temperature 650-750°C. Further, a thin pulp is prepared from the granules by adding water into the vessel with the granules until achieving water to granules ratio of 1.3:1. The pulp preheated to temperature 90-95°C is then fed into a mixing reactor where it is mixed with 36% hydrochloric acid, and the kalolin clay is leached for 1.5-2.0 hours while feeding water vapour at temperature 160-170°C in amount of 100 kg/h. Temperature of the leaching process is kept in the range of 100-105°C while continuously stirring the pulp with a mixer at a rate of 120 rpm. The obtained solution of a mixed aluminium dihydroxochloride coagulant and a silicic acid coagulant is pumped into a floatation chamber and an anion-active flocculant is added for precipitation of insoluble residual sludge. The aluminium dihydroxochloride coagulant is separated from the sludge on filters. Use of kaolin clay as the starting material enables to avoid the use autoclave equipment in the process and treatment thereof at low temperatures.

EFFECT: obtained coagulant has high consumer properties at low cost of the end product.

2 cl, 1 ex