GB269778A - Improvements in the removal of phosphorus from metalbearing solutions - Google Patents

Abstract

269,778. Stevens, R. H., Norris, G. C., and Watson, W. N. Aug. 23, 1926. Zinc, copper, and vanadium sulphates; metallic salts in general; ferric phosphate. - Phosphorus is removed from hydrometallurgical solutions by precipitating it as ferric phosphate. A soluble ferric compound is added to, or caused to be present in, the solution under treatment, and ferric phosphate precipitated therefrom either by neutralization with a base such as zinc oxide or lime and preferably at an elevated temperature such as 55‹ C., or by heating the weakly acid solution to a temperature of 60-90‹ C., and preferably to 80‹ C. At least one part by weight of ferric iron for each part by weight of phosphorus pentoxide should be present in the solution. The invention is particularly applicable to treating solutions obtained by leaching zinc, copper or vanadium ores with sulphuric acid. In such cases, after addition of ferric sulphate, the phosphorus may be removed together with silica, iron, and alumina by precipitation by means of slight excess of a base, and the precipitate be granulated, and subjected to acid washes to recover metallic values, in the manner described in Specification 274,297; or the phosphorus may be separately precipitated, either by adding sufficient only of the base to throw down the ferric phosphate, or by heating the slightly acid solution. In treating solutions obtained from vanadium ores, in which the vanadium is present in the pentavalent state, the vanadium must first be reduced to the more soluble tetravalent state; this may be effected by adding ferrous sulphate to the solution prior to purification, whereby also the ferric sulphate necessary for precipitation of the phosphorus is formed. The invention described in Specification 3196/79, [Class 90, Non-metallic elements], is disclaimed.