Recovery of Titanium by Solvent Extraction from Waste Sulfuric Acid Discharged in Titanium Dioxide Production

The recovery of titanium by solvent extraction from spent sulfuric acid discharged in titanium dioxide production,using primary amine N1923 and 2-octanol as agents was investigated. The effects of various process factors including stirring rate,2-octanol concentration,O/A phase ratio,extraction temperature and time on the phase disengagement and separation of titanium and iron were emphatically studied,and the influence of ammonia on stripping of titanium was also researched. The results show that using 20(v/v)% N1923 as extractant,4(v/v)% 2-octanol as modifier and 76(v/v)% sulfonated kerosene as diluent,the single stage extraction rate of titanium is above 96% with about 4% iron co-extracted at O/A=1:1,stirring rate 150 r/min,extraction temperature 30℃ and contact time 3 min. The phase disengagement time can be significantly decreased from 23 min to 4 min by addition of 2-octanol. Titanium can be effectively stripped by ammonia and 96% of single stage stripping rate for titanium is obtained with only 3 min for equilibrium. The oxidation of iron can be avoided by extraction under N₂ atmosphere with less than 0.5%iron co-extracted. The processes mentioned above was applied to industrial waste sulfuric acid discharged in titanium dioxide production,confirming the feasibility of selective and efficient recovery of titanium from industrial spent sulfuric acid by N1923-2-octanol-kerosene extraction system.