GB1051521A - Improvements in or relating to a process for the production of substantially iron free aqueous solution of phosphoric acid - Google Patents

Abstract

1,051,521. Removing iron from aqueous phosphate-containing liquor. ISRAEL MINING INDUSTRIES-INSTITUTE FOR RESEARCH & DEVELOPMENT. Jan. 26, 1965 [Feb. 20, 1964], No. 3320/65. Heading C1A. A substantially iron-free aqueous acidic solution containing phosphate, chloride and sulphate anions, and cations present in phosphate rock, which may be further processed to produce phosphonic acid is produced from an aqueous liquor containing the above ions and also iron, by extracting the liquor with a solvent selected from the group consisting of aliphatic alcohols, ketones, and esters of limited mutual miscibility with water, the total volume of solvent used being less than the volume of said liquor, and separating the iron containing extract from the liquor. The volume of solvent is preferably 1 volume to 5-10 volumes of liquor. Solvents preferred are iso-amyl alcohol, aliphatic alcohols with more than 5 carbon atoms and esters containing from 5 to 18 carbon atoms, particularly amyl acetate, other solvents detailed are di-isobutyl ketone, hexanol, octanol and cyclohexanone. The solvents may be mixed with an organic liquid with dielectric constant from 27 to 45, e.g. nitrobenzene. The starting liquor preferably contains 40-80 grams per litre of hydrochloric acid. The organic extract may be stripped of any coextracted P 2 O 5 by contacting with an aqueous recycle containing ferric chloride and hydrochloric acid and the iron may then be removed from the organic extract by washing with water. Alternatively the organic extract may be treated to reduce any trivalent iron to bivalent iron and the bivalent iron may be removed from the extract by precipitation or by extraction with water.