PROCESS FOR THE PRODUCTION OF TITANIUM DIOXIDE

摘要

In the manufacture of titanium dioxide by the sulphate process, waste materials are produced which pollute the environment. These include the washing filtrates produced during the washing of the titanium dioxide hydrate. Furthermore, during this process and during other processes, sulphur dioxide-containing waste gases are given off. The environmental pollution by these waste materials should be reduced. The washing filtrate is used for removal of the sulphur dioxide from the waste gas. Simultaneously, the sulphuric acid content of the washing filtrate is increased, and the sulphuric acid-containing process solution obtained from the washing filtrate is used in the titanium dioxide production process. The waste gas and the washing filtrate are passed in mutual countercurrent through a plurality of scrubbing stages and brought into contact by distribution of the wash liquid into the waste gas in scrubbing towers. The sulphuric acid content of the wash liquid changes stepwise from scrubbing step to scrubbing step. The sulphur dioxide content of the waste gas is reduced to a value below the legally permitted threshold value. The sulphuric acid-containing process solution is returned to the digest and/or is used to dissolve the digest cake, and the sulphuric acid formed from the sulphur dioxide is thus profitably utilised.