GB1125234A - Process and apparatus for the concentration of aqueous solutions and suspensions - Google Patents

Abstract

1,125,234. Ammonium salts; phosphoric acid- SINCAT-SOC. INDUSTRIALE CATANESE S.p.A. 16 June; 1966 [18 June; 1965], No. 26936/66; Heading C1A. [Also in Division- B1] An aqueous solution or' suspension is concentrated in a vertical elongated vessel which has a section 5 of upwardly increasing crosssection, by dispersing the solution or suspension through inlet 4 into a stream of hot gas, at a temperature of 70-1100‹ C., introduced through inlet 2 and rising up through the vessel` so that there is established, in the conical section 5, a fluidized bed of droplets of solution or suspension from which Water vaporizes from the' droplets into the rising gas stream which carries the relatively concentrated droplets from the bed into a cyclone separator 8 where the required concentrate collects in the discharge end 9. The solution or concentrate is introduced into the vessel at a constriction 3 where the gases have a velocity between 20 and 100 m/sec. The included angle of the conical section 5 is preferably 6 to 9 degrees. In the case of substances or mixtures of substances of low melting point, a molten product may be obtained at the outlet of the concentrator. The process is suitable for the concentration of phosphoric acid from 30% up to 64% by weight P 2 O 5 by using gases having an inlet temperature of up to 700‹ C. Fluorine-containing impurities in wetprocess phosphoric acid are, to a great extent eliminated in the gases discharged at 10 from separator 8. The purified product acid is suitable for the production of calcium phosphate for fodder. The process may also be used for the concentration of a solution of ammonium sulphate, or a slurry of ammonium nitrate and phosphate, or a slurry comprising NH 4 H 2 PO 4 , NH 4 NO 3 and KNO 3 . The concentration of sulphuric acid and of solutions alkali metal hydroxides are briefly referred to.