PURPOSE: To easily and inexpensively finish a thin acid from production of titanium dioxide and to convert a useful material further to a useful form by forming solid ammonium sulfate after removal of a metal compd. under special conditions.
CONSTITUTION: The filtrate formed by adjusting the thin acid to pH 4 to 6 with ammonia at 70 to 110°C, filtering a compd., such as titanium or vanadium, having poor solubility, adjusting the pH to 7 with ammonia and simultaneously oxidizing the compd. with air/oxygen and filtering metal ions and manganese compd. is brought into contact with the ammonium salt of the deriv. of the phosphoric acid or phosphoric acid in the org. soln. at 60 to 95°C to admit the ammonium ions into the filtrate and to admit the ions of magnesium and manganese into the org. soln. Sulphuric acid is added to the org. soln. and Mg and Mn are removed. The soln. is reused by adding ammonium hydroxide. An aq. ammonium sulfate soln. is subjected to, evaporative crystallization if needed after removal of the Mg and Mn in the filtrate, by which the solid ammonium sulfate is formed.
FURANKU KAEIHEGENSU
DOMIEN SURUITSU
