Method of pre-concentration of the thin acid produced by the sulphate process in titanium dioxide production and use of a device for that process.

摘要

The process utilises heat from the hot unpurified calcination waste gases produced in the calcination of the titanium dioxide hydrate, diluted acid being introduced into an acid circuit, the circulating acid being brought into direct contact with the calcination waste gases in a Venturi scrubber and a part of the circulating acid being withdrawn as preconcentrated acid from the acid circuit. A part of the circulating acid is mixed rapidly at the upper end of the Venturi scrubber with the calcination waste gases, a second part at the same height is applied via a weir to the inner wall of the Venturi scrubber and is mixed with the calcination waste gases in the Venturi throat. The calcination waste gas is separated off from the acid beneath the Venturi scrubber. The acid is preconcentrated from 20 - 24% H2SO4 to 25 - 28% H2SO4 and the calcination waste gas is preferably cooled from 250 - 400 DEG C to 85 - 100 DEG C.