Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group ivb metal
Patent
1992-11-02
1995-06-27
Shah, Mukund J.
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group ivb metal
423 80, 423 83, 423 86, C01G 2300, C01G 2500, C01G 2700, C22B 3410
Patent
active
054277493
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the treatment of titaniferous ores, for upgrading the titania content thereof.
In a particular embodiment the present invention provides a process for the removal of all or part of any iron, magnesium, manganese and aluminium from titanium bearing mineral ores or concentrates. In a general aspect the process of the invention comprises three basic steps, namely
In step (i) the iron content of the titaniferous mineral is partially converted to metal by gaseous or carbothermic reduction.
In step (ii) the product of step (i) is subjected to an aqueous treatment, resulting either in the dissolution of the metallic iron content of the mineral or in the conversion of the metallic iron to a separable iron oxide product.
In step (iii) the titaniferous product of step (ii) is subjected to a leaching treatment, using one of a number of possible reagents, for at least partial removal of residual iron, magnesium, manganese and aluminium. The titaniferous product of leaching will then be of particularly high titania content and may be used in place of natural rutile oar other high titania content materials.
Additional steps may be employed as will be described below.
In the prior art synthetic rutile has been formed from titaniferous minerals, e.g. ilmenite, via various techniques. According to the most commonly applied technique, as variously operated in Western Australia, the titaniferous mineral is reduced with coal or char in a rotary kiln, at temperatures in excess of 1100.degree. C. In this process the iron content of the mineral is substantially metallized. Sulfur additions are also made to convert manganese impurities to sulfides. Following reduction the metallized product is cooled, separated from associated char, and then subjected to aqueous aeration for removal of virtually all contained metallic iron as a separable fine iron oxide. The titaniferous product of separation is treated with 2-5% aqueous sulfuric acid for dissolution of manganese and some residual iron. There is no substantial removal of magnesium or aluminium from the product at any point in this process, and iron removal is only effected in the aeration step. After calcination the synthetic rutile contains approximately 92% TiO.sub.2 and 1-2% iron as oxide.
The major use for synthetic rutile is as feedstock for the production of white titanium dioxide pigment via the chloride process. According to this process titania bearing minerals are charged with a carbon source to a fluidized bed chlorination reactor wherein gaseous titanium tetrachloride is formed. The titanium tetrachloride is subsequently condensed and purified and then is oxidized to titanium dioxide for use in pigments. The impurities iron, magnesium, manganese and aluminium in titaniferous feedstocks each have deleterious effects, either in chlorination, condensation or purification. Where a titaniferous mineral, such as ilmenite, has high levels of magnesium or aluminium it cannot be converted to a synthetic rutile by the Western Australian process which does not remove these impurities. Further, residual iron and manganese, as well as magnesium and aluminium, result in performance based penalties for synthetic rutile feedstocks to chlorination.
In other prior art inventions high degrees of removal of magnesium, manganese, iron and aluminium have been achieved. In one such process the ilmenite is first thermally reduced to substantially complete reduction of its ferric oxide content, normally in a rotary kiln. The cooled reduced product is then leached under 35 psi pressure at 140.degree.-150.degree. with excess 20% hydrochloric acid for removal of iron, magnesium, aluminium and manganese. The leach liquors are spray roasted for regeneration of hydrogen chloride, which is recirculated to the leaching step.
In other processes the ilmenite undergoes grain refinement by thermal oxidation followed by thermal reduction (either in a fluidized bed or a rotary kiln). The cooled, reduced product is then subjected to atmospheric leaching with excess 20% hydrochloric
REFERENCES:
patent: 4097574 (1978-06-01), Auger et al.
Becher et al., "A New Process for Upgrading Ilmenitic Mineral Sanas", Australian Institute of Mining Proceedings, 6 1965, pp. 21-43.
"The Reduction of Radionuclides in Titaniferous Feedstocks", Ellis et al, Industrial Minerals International Congress, pp. 102-108. (1992 or later).
"The AMC Narngulu Synthetic Rutile Plant", Cassidy et al, The AusIMM Perth Branch, Australia, Sep./Oct. 1986, pp. 123-128.
"Direct Reduction Technology-The Western Titanium Process for the Production of Synthetic Rutile, Ferutil, and Sponge Iron", Bracanin et al, Proc. Australas No. 271, Sep. 1980, pp. 33-42.
"Ilmenite Research in CSIRO-Part 1", pp. 4-9.
"Investigation of the Segregation of Iron From Ilmenite", Tittle et al, Mining & Metallurgy, Sep. 1973, pp. C135-C139.
"The Modified Metallurgical Upgrading of Ilmenite to Produce High Grade Synthetic Rutile", Rolfe, The AusIMM Conference, W. Australia May 1973, (incomplete).
"Reduction of Ilmenite in a Commercial Rotary Kiln-An X-Ray Detraction Study", Grey et al, AusIMM Conference, W. Australia May 1973, pp. 583-605.
"Synthetic Rutile-Its Present and Future Role as a Feedstock in the Pigment and Metal Industry", Cassidy et al, 7th Industrial Minerals Int. Congress, Apr. 1986, pp. 207-215.
"The Development of a Direct Reduction and Leach Process for Ilmenite Upgrading", Bracanin et al, pp. 209-259. (incomplete).
Grey Ian E.
Hollitt Michael J.
O'Brien Brian A.
Grumbling Matthew V.
Shah Mukund J.
Vigil Thomas R.
Wimmera Industrial Minerals Pty. Ltd.
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