GB269780A - Improvements in the recovery of vanadium - Google Patents

Abstract

269,780. Stevens, R. H., Norris, G. C., and Watson, W. N. Aug. 23, 1926. Drawings to Specification. Vanadium sulphates and oxide; ferric and zinc vanadates; zinc sulphate.-Vanadium present in sulphate solutions is reduced from the pentavalent to the tetravalent condition, as by means of ferrous sulphate or sulphite, or by zinc dust followed by ferrous sulphate, impurities, such as silica, ferric iron, and alumina, are then precipitated from the solution by addition of a basic material, and the vanadium is then converted to the pentavalent or trivalent condition to facilitate its subsequent precipitation as vanadate or oxide respectively. The invention is described as applied to the treatment of a solution obtained from a zinc-vanadium ore by leaching it as described in Specification 269,777. The solution is neutralized, after the vanadium has been reduced by the addition of a base such as zinc oxide, lime, or limestone, and the precipitate removed. Copper, if present, may be removed with the other impurities by the addition of a soluble sulphide after the solution has been neutralized, and phosphorus may also be removed at this stage in the manner described in Specification 269,778. Vanadium may be recovered from the impurity precipitate by subjecting the latter, in the form of a filter cake, to weak acid washes as described in Specification 274,297. The purified solution is next treated, either with zinc dust to reduce the vanadium to the trivalent state, or with acid to obtain an acidity of 2-5 grms free sulphuric acid per litre and then with manganese dioxide to reoxidise the vanadium to the pentavalent state. From the solution so obtained, preferably heated to 50‹ C., vanadium is precipitated by means of a base, a ferric compound being added when pentavalent vanadium is present, as described in Specification 269,779, and the vanadium being then precipitated as ferric or zinc vanadate, whilst when trivalent vanadium is present, vanadium trioxide is obtained. After the removal of the precipitate, the zinc solution is, if necessary, further purified before being subjected to electrolysis. A flow sheet for the application of the process to a zinc-vanadium ore is included in the Specification.