GB249465A - A process for purifying plumbiferous chloride liquors - Google Patents

Abstract

249,465. Consortium f³r Nassmetallurgie. March 20, 1925, [Convention date]. Addition to 240,401. Lead chloride, carbonate, chromate, oxychloride, sulphate, and other salts. - The solutions of lead obtained by treating plumiferous materials with chloride solutions, as described in the parent case, are purified by treatment with such an amount of a substance alkaline to litmus such as lime, that a small proportion of the lead, for instance 1 per cent, is precipitated. The solutions may be treated after separation from the residues, or in presence of the residues, and after treatment with calcium carbonate and oxidation, for instance with chlorine or chlorates if desired. This treatment precipitates the iron more rapidly than does the process of the parent case. The solution may be treated with more lime, if any iron remains, as shown by testing with ammonium thiocyanate. The solution may be separated :from the residue and precipitate if desired, and is next purified from metals such as noble metals, bismuth, and arsenic, and from excess of oxidizing agent by adding a soluble sulphide in sufficient quantity to precipitate a small proportion of the lead, for instance 0.5 per cent. It is not necessary to neutralize the whole of the oxidizing agent present, as the sulphide precipitate can exist in presence of a small quantity of free chlorine. The precipitates obtained, which contain lead, may be treated as plumbiferous material for extraction by the process of the parent case.