GB1373912A - Manganese compounds - Google Patents

Abstract

1373912 Recovering manganese compounds from liquors KODAK Ltd 28 Feb 1972 [30 Nov 1970] 56792/70 Addition to 1312252 Heading C1A Mn(OH)2 is precipitated from liquors containing a manganese salt, e.g. MnSO4, by adding to the liquor an aq. soln. of NH3 or a substituted NH3 having a pKa greater than 9, the soln. having a pH of at least 10, until the pH falls to a value exceeding 9À5 and then separating the hydroxide. The hydroxide may be converted into Mn3O4, manganese acetate, hydrate or dehydrate. The substituted NH3 may be a monodi or tri-alkyl (or aryl), amine or a nitrogenous heterocyclic base. Mn3O4 may be prepared by heating the hydroxide in deionized water with air or O2 at elevated temp and pressure Mn acetate tetrahydrate may be formed by dissolving the hydroxide in acetic acid and evaporating the liquor. The tetrahydrate may then be dehydrated by spray drying. The Mn liquor prior to precipitation of Mn(OH)2 may be treated (a) at a pH of 6À6 with Na2S to ppt. Cu, Co, Pb, Ni and Mo sulphides, and (b) with NaF or NaHF2 to solubilize SiO2. The Mn salt may be in an amount of 5% by wt. The Mn(OH)2 precipitation may be carried out at a temp. of 25-35‹ C. with the exclusion of air.