PROCESS FOR THE TREATMENT OF THE IRON (II) SULFATE - CONTAINING DILUTE SULFURIC ACID SOLUTION OBTAINED AS THE HYDROLYSIS FILTRATE FROM THE HYDROLYSIS OF TITANYL SULFATE SOLUTIONS IN THE PREPARATION OF TITANIUM DIOXIDE

摘要

A process for the treatment of the iron(II) sulfate containing dilute sulfuric acid solution obtained in the production of titanium oxide by hydrolysis from titanyl sulfate solutions as the hydrolysis filtrate. The hydrolysis filtrate is concentrated with the formation of a suspension containing precipitated metal sulfates to a H2SO4 content of 55 to 75% by weight. The metal sulfates precipitated are separated at an elevated temperature on a screen centrifuge and washed successively at an elevated temperature with 2 to 4% by volume of the warm hydrolysis filtrate and 1 to 2% by volume of warm water, with respect to the volume of the suspension. All of the filtrates are recycled into the titanium dioxide production process and/or returned to the process of processing the hydrolysis filtrate. Prior to the final concentration and cooling of the preconcentrated hydrolysis filtrate, part of the iron may be precipitated and separated as iron(II) sulfate heptahydrate.