Kronos Titan-g.m.b.h.

Kronos, Inc.

Rheox Inc.

Hans Thumm

Achim Hartmann

Franz Rosendahl

Siegfried Blumel

Hans-Hermann Luginsland

Dieter Schinkitz

Achim M Kulling

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. If, on the other hand, a rigid filter cake is desired by, for example, a vacuum filtration, a minimum quantity of multivalent anions is necessary for the formation of the rigid filter cake. The solids content is, however, lowered in comparison to the thixotropic filter pastes. Where this minimum quantity of multivalent anions is exceeded, the solids content declines further. The rigid filter cakes can be rendered flowable through the direct admixing of dispersing agent. Hydrogen peroxide is particularly preferred as a dechlorinating agent.

Process for preparing high solids content titanium dioxide suspension

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.

High solids content titanium dioxide suspension

In order to treat metal chlorides obtained in the form of dust collector solids in the production of titanium dioxide by the chloride process, the inert constituents, especially particulate coke, is separated then the metals are selectively precipitated and a maturing phase under oxidative conditions is provided for. The residue consisting of metal hydroxides is also not thixotropic in the absence of inerts. As a result, the material to be deposited has been cut in half.

Process for the production of disposable products from metal chlorides

A process for the production of coarse scrubbing aggregates of TiO.sub.2 particles by vapor phase oxidation of titanium tetrachloride. The particle aggregates of sizes above 0.15 mm are separated from the TiO.sub.2 fines by wet screening on a moving screen, calcined and returned to the process. In a preferred embodiment of the process, the titanium dioxide prior to calcination is admixed with 0.01 to 0.3% by weight alkaline hydroxides (related to anhydrous TiO.sub.2), hard particle aggregates of sizes between 0.2 to 2.0 mm being generated that are returned to the hot reaction mixture and used for the prevention of deposit formation on the surfaces of the heat exchanger. The process can be carried through in such a way that the quantities of coarse scrubbing TiO.sub.2 aggregates per unit of time consumed by abrasion and newly formed by sintering are equal, their percentages in recycling TiO.sub.2 thus remaining constant which simplifies the TiO.sub.2 production process.

Process for the production of coarse, scrubbing aggregates of titanium

Process for the production of a nearly aluminum chloride-free titanium tetrachloride from titaniferous raw materials containing larger quantities of aluminum compounds in a fluid bed with the addition of a reducing agent. In the process, sodium chloride is added to or formed in the reaction mixture before the first condensation step. A sodium chloride/aluminum chloride complex is formed thereby, which is discharged together with the chloride mixture and separated from said mixture together with the metal chlorides of lower volatility. The maximum quantity of NaCl needed is 1 mole per mole Al contained in the titaniferous raw material and per mole of iron (III) chloride, calculated as FeCl.sub.3, that may form.

Process for the production of nearly aluminium chloride-free titanium

The dust produced in the chlorination of titaniferous ores comprises essentially particulate ferrous chloride plus solid contaminants including coke and various metal chlorides and oxides and is oxidized in successive stages at relatively low temperatures to recover particulate iron oxide and gaseous chlorine.

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Leverkusen, Germany

Hans Thumm