Abstract: In the preparation of a suspension with a high content of titanium dioxide, which has been produced according to the chloride process, a finely divided titanium dioxide is slurried, in unflocculated condition without use of a dispersing agent, dechlorinated and then filtered. The content of multivalent anions can be controlled in the slurry before the filtration through suitable dechlorinating agents, particularly hydrogen peroxide and/or sodium hydrogen sulfite, and thereby the solid content in the filter cake and the consistency of the filter cake are advantageously influenced. If, on one hand, no or only few multivalent anions are present, a thixotropic filter cake with a high solids content is obtained in a pressure filtration. The filter cake is converted into a titanium dioxide suspension with a high solids content through feeding into a titanium dioxide suspension to which a dispersing agent has been added.

Abstract: A finely divided chloride process titanium dioxide prepared without the use of a dispersing agent. The slurry is dewatered via filtration, and the resulting filter cake is made flowable with an anionic dispersing agent. In order to attain a filter cake with very high solids content, the slurry should contain no, or only very few, multivalent anions. The conditions regarding the content of multivalent anions of the slurry are achieved by selection of suitable dechlorinating agents, especially hydrogen peroxide. The filter cake is thixotropic and is made flowable by the fact that it is put into the "diluted" dispersing agent, especially into a part of the titanium dioxide suspension to which the required quantity of dispersing agent has previously been added. Titanium dioxide suspensions with solids content of approximately 78% are thereby obtained and are of particular use in the paper industry.

Abstract: A process produces fine particle titanium dioxide essentially transparent to visible light and essentially UV radiation absorbing. During preparation of the titanium dioxide product, tin dioxide with a particle size of 1 to 10 nm, and preferably 1 to 4 nm, is added, in an amount of 0.5 to 10 weight percent with respect to TiO.sub.2. The particle size of the titanium dioxide is specifically adjusted by the tin dioxide addition. Acicular particles are rounded by heat-treatment between 300.degree. and 800.degree. C., and preferably between 400.degree. and 600.degree. C. The particles can be post-treated to produce a coating of inorganic and/or organic substances. The fine particle titanium dioxide can be prepared by the decomposition of sodium titanate with hydrochloric acid or by suitable hydrolysis of a tetravalent titanium compound which leads to rutile formation.

Abstract: A process for the improvement of titanium dioxide pigments by a post-treatment, wherein the titanium dioxide pigment produced by any process, in the form of an aqueous suspension and in any order, is treated with an aqueous titanium oxide chloride solution resulting from the scrubbing of off-gases derived from the production of titanium tetrachloride and, optionally, with one or more other water-soluble metal salts which when neutralized form difficult-to-dissolve oxide hydrates and/or other difficult-to-dissolve compounds, and/or optionally with a water-soluble silicate, and where difficult-to-dissolve oxide hydrates and/or other difficult-to-dissolve compounds are precipitated onto the titanium dioxide pigment from the titanium oxide chloride solution and, if present, from the other metal salts and/or the silicate, and where the titanium dioxide pigment thus treated is recovered such as by being separated from the suspension, washed, dried and milled.

Abstract: A novel titanium dioxide hydrate is provided whose structure exhibits X-ray diffraction peaks at 24.6.+-.0.4.degree. and 48.+-.0.4.degree., and which is suitable as an adsorbent material. A process for preparing the novel titanium dioxide hydrate also is provided which includes hydrolyzing a specific titanium sulfate solution and thereafter flocculating colloidal titanium dioxide hydrate by the addition of a monobasic acid and recovering the titanium dioxide hydrate.