| 摘要 |
Corrosion during the prodn of Ti02 is reduced or prevented by using for a) the known digestion of Ti raw material by H2S04, hydrolysis of the titanyl sulphate and the washing of the hydrolysate b) aq liquids contg less than 500, pref less than 250 ppm Cl- and less than 250, pref less than 150 ppm Ca2+. The diluted acid sepd from the hydrolysate and worked up in known manner contains less than 2g, pref less than 1g Cl-/kg H2S04 and less than 1g, pref less than 0.6 g/kg H2S04. The aq liquids are pref Ca free condensed vapour from the dilute acid concentration, diluted H2S04 from the hydrolysate bleaching, sulphuric wash water, dilute acid fractions and/or water. ADVANTAGE - The diluted acid can be worked up with few problems and without difficulties caused by deposit formation and corrosion. |
