Method for processing the dilute iron(II) sulphate-containing sulphuric acid solution arising as the hydrolysis filtrate when obtaining titanium dioxide by hydrolysis from titanyl sulphate solutions

The hydrolysis filtrate is concentrated to give a suspension containing precipitated metal sulphates and having an H2SO4 content of 55 to 75% by weight. The precipitated metal sulphates are separated at elevated temperature on a screen centrifuge, and successively washed at elevated temperature with 2 to 4 per cent by volume of warm hydrolysis filtrate and 1 to 2 per cent by volume of warm water, based on the volume of the suspension. All the filtrates are recycled to be reused in the context of titanium dioxide production and/or in the method for processing the hydrolysis filtrate. Prior to the final concentration step, pre-concentrating and cooling of the pre-concentrated hydrolysis filtrate can be employed to deposit and to separate part of the iron as iron(II) sulphate heptahydrate.