Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1997-02-19
1998-12-29
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
75957, 423610, C22B 3412, C21B 1300
Patent
active
058534520
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the production of synthetic rutile of a quality suitable for use as a feedstock in the production of TiO.sub.2 pigment via the chloride route.
The chloride route to TiO.sub.2 pigment production has become increasingly important in view of environmental concerns about the acid wastes produced by the sulphate TiO.sub.2 process which can accept lower grade titaniferous ores.
Commercial synthetic rutile production for use as a feedstock in the chloride route is normally based on ilmenite feedstock containing 54 to 60% TiO.sub.2, with a distinct preference for material of at least 58% TiO.sub.2 content.
Various proposals have previously been made for processing lower grade titaniferous materials as alternative sources of TiO.sub.2 pigment. For example, a process has been used which involves blending ilmenite with coke and smelting in an electric arc furnace to separate most of the iron as saleable pig iron and to form a titania-enriched slag.
Enrichment of the TiO.sub.2 content of conventional titanium slags has also been disclosed by dc arc smelting.
EP-A-0266975 (corresponding to U.S. Pat. No. 4,701,217) discloses a method of smelting metal oxide material comprising forcibly circulating a molten carrier material in a closed loop path serially through a smelting reduction zone, a slag separation zone and a heating zone; contacting the metal oxide material with the molten carrier material; introducing a carbonaceous reductant to the molten carrier material; at least partially reducing the metal oxide to metal by the carbonaceous reductant in the smelting reduction zone, the metal oxide and carbonaceous reductant being utilised in proportions such that the carbon from the carbonaceous reductant is converted to carbon monoxide; reacting the carbon monoxide with oxygen in the heating zone at the surface of the molten carrier material so that the heat generated by the reaction is transferred to the molten carrier material which is circulated to the smelting reduction zone; separating slag from said molten carrier material in said slag separation zone before the molten carrier material is circulated to the heating zone so that the surface of the molten carrier material which is circulated to the heating zone is substantially free of slag; and recovering said metal. Amongst a large number of possible feedstocks which are described, EP-A-0266975 discloses the application of the above process to ilmenite to form titaniferous slag (a source of synthetic rutile) and pig iron, but there is no detailed example of this and no proposals as to how to upgrade the quality of the titaniferous slag to the quality required for TiO.sub.2 pigment production via the chloride route.
According to the present invention, there is provided a method of upgrading titaniferous material containing iron oxide, comprising contacting the titaniferous material with molten iron containing dissolved carbon so as to reduce at least some of the iron oxide in the material to iron and produce a titania slag having a lower iron oxide content.
Most preferably the method of upgrading titaniferous material containing iron oxide, comprises the steps of circulating a molten carrier material comprising molten iron and dissolved carbon in a closed loop path through first and second hearths; introducing the titaniferous material into the carrier material in a heating zone in the first hearth so as to reduce iron oxide to iron and produce a titania slag having a lower iron content; removing the titania slag from the molten carrier material before the latter is circulated to the second hearth; introducing carbonaceous reductant into the molten carrier material so as to cause carbon to dissolve in the carrier material in the second hearth; and performing a further slag removal operation on the circulating molten carrier material before passing the latter to the first hearth.
In the above described method, the further slag removal operation effected in the second hearth after introduction of the carbonaceous reductant serves to remove slag
REFERENCES:
patent: 3326671 (1967-06-01), Warner
patent: 4701217 (1987-10-01), Warner
Patent Abstracts of Japan JP58049622, Mar. 23, 1983.
Andrews Melvyn
The University of Birmingham
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