Sulfate digestion process for high purity TiO2 from titania slag

A titania slag product of Rosetta ilmenite assaying 72% TiO₂ is treated by the sulfate process option of the pigmentary TiO₂ manufacture. The relevant factors of acid concentration, particle size, slag/acid ratio besides the reaction temperature, and time have been studied. After dissolving the cured mass in dilute acid and clarification, the obtained solution was subjected to hydrolysis of its titanium content. The final product was bleached under reducing conditions to redissolve the residual coloring impurities before being dewatered and calcinated. The obtained results indicated that a leaching efficiency of about 92% was realized due to the presence of some refractory components in the working slag material, namely, rutile and magnesium iron titanate. The obtained white pigment assay attained up to 99.85% TiO₂, while the analyzed impurities involve 77 ppm Mn and only 14 and 7 ppm of total iron and V, respectively.