Process for the recovery of greatly concentrated sulfuric-acid solutions by the treatment of diluted sulfate-containing sulfuric-acid concentrations

摘要

The processing of dilute sulphuric acid containing iron(II) sulphate, such as arises in the production of titanium dioxide by the sulphate process, for re-use in the process is effected by preconcentrating in several stages (V1, V2, V3) from less than 28% to 40 - 65% concentration, for example in vacuum evaporators using the steam arising in a later stage, and by concentrating (A) to 70 - 85%, precipitated metal salts being separated off, wherein already concentrated acid, largely free of metal salt, is admixed M) to the preconcentrated acid (V3) so that the sulphuric acid concentration of the mixture becomes about 70%. The remainder of the concentrated acid which is not circulated is concentrated up to 85 - 88% (H) and re-used for the digestion of titanium ore. If desired, the sulphuric acid concentrated up to 85 - 88% can also be admixed to the preconcentrated sulphuric acid. IMAGE