Abstract: A process for the extensive removal of undesirable metal ions, particularly vanadium ions, in the course of the concentration of dilute iron(II) sulfate-containing sulfuric acid solutions. The sulfuric acid solutions are concentrated by the evaporation of water and the separation of iron(II) sulfate to a content of 60 to 70% by weight H.sub.2 SO.sub.4. According to the invention, the content of trivalent titanium in the solution is adjusted such that the content of trivalent iron does not exceed 0.1 g/l. The trivalent titanium may be added from the outside, if not already present in an adequate amount in the solution, or may be formed in situ from the tetravalent titanium present in the solution by the addition of a reducing agent. Prior to the final concentration, part of the iron may be precipitated and separated as iron(II) sulfate heptahydrate by means of preconcentration and cooling of the preconcentrated sulfuric acid solution.

Abstract: A process is provided wherein solid mixtures of metal chlorides of, for example, ferric chloride, ferrous chloride, vanadium chloride and chromium chloride are (1) mixed with an alkaline material such as, for example, calcium oxide, calcium hydroxide and calcium carbonate, followed (2) by adding water to the resulting mixture to granulate said mixture whereby the metal chlorides are rendered substantially insoluble in water.