| 摘要 |
Composite titanium pigments are made by mixing mechanically a hydrated titanium compound, precipitated from an acid solution containing titanium, with an inert extender, and treating the titanium compound, either before or after mixing with the extender with a reagent to neutralize, partly or wholly, the free acid contained therein, washing the neutralized product to remove soluble salts and finally calcining the mixture. Neutralizing agents specified are:--barium chloride alone or mixed with caustic soda, barium hydrate, calcium carbonate or chloride, or lime. For example, a titanium oxide pulp containing free sulphuric acid is mixed with milled natural barytes or gypsum as extender, and barium chloride solution is added. The mixture is warmed, diluted with water, filtered and the resulting precipitate is washed and calcined at 700 to 1100 DEG C. Other inert extenders specified are china clay, alumina, silica, or blanc fixe. Before calcining the mixture, there may be added a small amount of phosphoric acid or a fusible salt such as calcium or baium phosphate, or compounds may be added to the titanium compound to form such fusible salts with the free acid. Specifications 149,316, [Class 95], and 374,420 are referred to.
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