Bayer Aktiengesellschaft

Walter Gutsche

Peter Woditsch

Peter Panek

Gunter Lailach

Rudolf Gerken

Gerhard Winter

Gerhard Wiederhoft

Wolfgang D Muller

Hilmar Rieck

Walter Deissmann

In the preparation of titanium dioxide comprising autothermically digestion a titanium-containing raw material with sulphuric acid to form a solid relatively easily soluble digestion cake containing titanyl sulphate, extracting metal sulphates from this cake by water or dilute sulphuric acid, separating the undissolved residues and, optionally after crystallization of iron sulphate heptahydrate, hydrolyzing the titanyl sulphate to produce titanium oxide hydrate, and calcining the titanium oxide hydrate to titanium dioxide, the improvement which comprises adding to the raw material a metal sulphate and effecting the autothermic decomposition with sulphuric acid of about 80 to 88% concentration. Advantageously the acid is obtained by mixing dilute acid with concentrated sulphuric acid or oleum, some of the dilute acid and metal sulphate coming from a by-product filter cake produced in the course of the process.

Process for the preparation of titanium dioxide

A process for the production of a hydrolyzable titanyl sulphate solution comprising contacting sulphuric acid of about 86% concentration with a mixture of slag and ilmenite, the ratio of H.sub.2 SO.sub.4 to TiO.sub.2 in the mixture ranging from about 1.7:1 to 2.2:1 and the mol ratio of Ti(III) to Fe(III) in the mixture ranging from about 25:1 to 1.4:1, the slag having a TiO.sub.2 content of &gt;80% and a Ti(III) content of about 22 to 40% calculated as TiO.sub.2, and the ilmenite having a Fe(III) to Fe(II) ratio from about 1:1 to 10:1, and adding water if necessary to bring the concentration of sulphuric acid to from about 86 to 96%.

Production of hydrolyzable titanyl sulphate solution

A process for the preparation of a hydrolyzable titanyl sulphate solution comprising adding sulphuric acid having a concentration greater than about 86% to a ternary mixture of two slags and an ilmenite to bring the proportion by weight of H.sub.2 SO.sub.4 to TiO.sub.2 to from about 1.7:1 to 2.2:1 and adding water, dilute sulphuric acid or oleum in amount sufficient to bring the H.sub.2 SO.sub.4 concentration to from about 86 to 96%, thereby to form the titanyl sulphate solution, the first slag having a TiO.sub.2 content greater than about 80% and a Ti(III) content of about 22 to 40%, the second slag having a TiO.sub.2 content of about 60 to 80% and a Ti(III) content of about 5 to 15%, and the ilmenite having a ratio of Fe(III) to Fe(II) of from about 1:1 to 10:1, the slags and ilmenite being present in such proportions that the ternary mixture of raw materials obtained has a molar ratio of Ti(III) to Fe(III).gtoreq.1.4.

Hydrolyzable titanyl sulphate solutions by decomposition of ternary raw

In the purification of impure titanium tetrachloride comprising adding an agent to said titanium tetrachloride and thereafter distilling off purified titanium tetrachloride while leaving the impurity in the distillation residue, the improvement which comprises employing as said agent at least one amine of the formula ##EQU1## in which R.sub.1 and R.sub.2 each independently is hydrogen, alkyl or alkenyl of up to 6 carbon atoms, cycloalkyl of 5 to 7 carbon atoms, or aryl, and

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Krefeld, Germany

Walter Gutsche