METHOD OF PREPARING HYDROXYAPATITE SUSPENSION Russian patent published in 1998 - IPC

FIELD: production of inorganic compounds. SUBSTANCE: invention relates to hydroxyapatite used in medicine as dental prosthesis material, prophylactic additive in production of dental paste and medical solutions (elixirs), confectionery pastilles and chewing gum, sorbent for drugs and various organic and inorganic substances, dental and osteosurgery materials, as well as filler or sorbent for gas-liquid chromatography. Method consists in interaction of calcium hydroxide with phosphoric acid in closed circuit, where calcium hydroxide suspension consecutively passes through two zones. Into the first zone, phosphoric acid is continuously fed in amount required to attain pH 10-11. Suspension stream moves with velocity 0.8-1.5 m/s and is retained for 1.0-1.5 s. Mixture is diluted in the second zone with calcium hydroxide suspension by 400-500 times and is returned into the first zone, circulation ratio being 4-5 times for 10-20 min period. After acid feed is stopped, mixture is additionally agitated for 10-12 min. Additionally agitated suspension is further processed with alternated agitation and filtration stages. EFFECT: enhanced process efficiency. 1 tbl