Process optimization of the extra-adding seeded hydrolysis of TiOSO4 to H2TiO3 by using the unenriched solution for the manufacture of TiO2 pigment

Abstract For the industrial manufacture of TiO2 pigments via the sulfate process, the particle size and distribution of H2TiO3 obtained by the thermal hydrolysis of TiOSO4 directly determine the quality of final TiO2 pigments. In this study, the extra-adding seeded hydrolysis of TiOSO4 to H2TiO3 by using the unenriched solution with an equivalent TiO2 concentration of 160 g/L and Fe/TiO2 ratio of 0.4 was studied. The effect of the process parameters was investigated to obtain the optimal conditions: seed-added amount = 1.5 wt%, F value = 1.9, and aging time = 35 min, at which, the H2TiO3 particles exhibit the narrowest particle size distribution. Importantly, it was demonstrated that the size of the as-obtained H2TiO3 particles becomes larger at the scenarios of smaller primary crystals due to their severer and stronger agglomeration. Furthermore, TiO2 pigments prepared from the H2TiO3 particles obtained at the optimal process conditions exhibit the best properties, and their total production cost can be reduced by about 5% by using the unenriched TiOSO4 solution instead of the enriched solution, which is of great industrial value.