GB552469A - Improvements in or relating to methods of recovering calcium-free beryllium sulphatecrystals - Google Patents

Abstract

552,469. Production of calcium-free beryllium sulphate crystals. BRUSH BERYLLIUM CO. Aug. 6, 1941, No. 10013. Convention date, Aug. 3, 1940. [Class 1 (iii)] Substantially calcium-free beryllium sulphate crystals are recovered from solutions containing more than about ¢ gm. calcium sulphate per litre by establishing in the solution such proportions of beryllium sulphate, free ammonium sulphate and calcium sulphate as to cause the latter to be held in solution when beryllium sulphate is crystallized out e.g. by evaporation under vacuum or by concentrating to saturation by heat and crystallizing by subsequent cooling. The proportions necessary in the solution are ascertainable from the curve shown, which indicates the influence of free ammonium sulphate on the equilibrium solubility of calcium sulphate at about 20‹C. in a solution containing approximately 635 gm. BeSO 4 , 4H 2 O per litre, which solution is therefore approximately saturated with beryllium sulphate. In the area below the curve the calcium is soluble; above and to the right, insoluble. This solution should contain not less than 110 gm. per litre of ammonium sulphate. The adjustment may be effected by adding ammonium sulphate and concentrating the solution so that it is saturated with beryllium sulphate while precipitating part of the calcium sulphate which is recoved by filtering. If aluminium sulphate is present this is crystallized out as alum with the calcium sulphate. In processes in which beryllium sulphate and alum are crystallized out together the invention may be applied to prevent precipitation of calcium sulphate therewith. Specification 500,469, [Group II], and U.S.A. Specifications 2,018,473, 2,204,221 and 2,268,903 are referred to.