RUTILE TIO2 SLURRIES

1400067 TiO 2 slurry AMERICAN CYANAMID CO 20 July 1972 [21 July 1971] 34104/72 Heading C1N A TiO 2 slurry with a solids content of at least 60% by weight is obtained by flocculating an aqueous slurry of anhydrous TiO 2 of particle size not in excess of 4 microns with a flocculating agent, dewatering the flocculated pigment to produce a filter cake having a solids content of 60 to 80% by weight, and reslurrying this filter cake by means of a dispersing agent to obtain the desired aqueous pigment slurry. The initial slurry of a solids content of, e.g. 20% may be obtained by wet grinding the crude pigment followed by hydro classifying or screening to remove particles greater than 4 microns. The flocculating agent may be MgSO 4 , MgCl 2 , BaCl 2 , H 2 SO 4 , HCl or HAc. The flocculated pigment may be washed suitably between initial and final dewaterings. The dispersing agent may be 2-amino-2-methyl-1-propanol, triethanolamine, sorbitol, mannitol or a sodium polymeric carboxylate. The reslurrying is preferably effected without further addition of water. The TiO 2 may be rutile or anastase and may contain Al 2 O 3 , MgO or ZnO.