Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group ivb metal
Patent
1997-01-06
1999-03-23
Bos, Steven
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group ivb metal
4231181, 423122, 423123, 423127, C01G 2300, C01B 3300, C01F 700
Patent
active
058855360
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to the treatment of a leachant used in leaching impurities from a titaniferous material to upgrade the titania content of the titaniferous material.
The term "titaniferous material" is understood herein to mean a material which contains at least 2 wt % titanium.
In particular the present invention relates to the treatment of a leachant to enhance the effectiveness of the leachant for the removal of impurities in titaniferous materials.
More particularly, although by no means exclusively, the present invention is concerned with minimising the effect on a leaching process of silica and alumina, which are present as impurities in many titaniferous materials.
In a particular embodiment the present invention provides a process whereby the concentrations of silica and alumina in a recycling leachant in a leaching process are maintained below concentrations that affect adversely the leaching process.
In industrial chlorination processes titanium dioxide bearing feedstocks are fed with coke to chlorinators of various designs (fluidised bed, shaft, molten salt), operated to a maxim temperature in the range 700.degree.-1200.degree. C. The most common type of industrial chlorinator is of the fluidised bed design. Gaseous chlorine is passed through the titania and carbon bearing charge, converting titanium dioxide to titanium tetrachloride gas, which is then removed in the exit gas stream and condensed to liquid titanium tetrachloride for further purification and processing.
The chlorination process as conducted in industrial chlorinators is well suited to the conversion of pure titanium dioxide feedstocks to titanium tetrachloride. However, most other inputs (i.e. impurities in feedstocks) cause difficulties which greatly complicate either the chlorination process itself or the subsequent stages of condensation and purification. The attached table provides an indication of the typea of problems encountered. In addition, each unit of inputs which does not enter products contributes substantially to the generation of wastes for treatment and disposal. Some inputs (e.g. heavy metals, radioactives) result in waste classifications which may require specialist disposal in monitored repositories. Preferred inputs to chlorination are therefore high grade materials, with the mineral rutile (at 95-96% TiO.sub.2) the most suitable of present feeds. Shortages of rutile have led to the development of other feedstocks formed by upgrading naturally occurring ilmenite (at 40-60% TiO.sub.2), such as titaniferous slag (approximately 86% TiO.sub.2) and synthetic rutile (variously 92-95% TiO.sub.2). These upgrading processes have had iron removal as a primary focus, but have extended to removal of manganese and alkali earth impurities, as well as some aluminium.
______________________________________ Elemental
Input Chlorination
Condensation
Purification
______________________________________
Fe, Mn Consumes Solid/liquid
chlorine, chlorides
coke, foul
increases ductwork,
gas volumes make sludges
Alkali Defluidise
& alkali earth
fluid beds due
metals to liquid
chlorides,
consume
chlorine, coke
Al Consumes Causes Causes
chlorine, corrosion corrosion,
coke makes
sludges
Si Accumulates Can encourage
May require
in duct distillation
chlorinator,
blockage. from product
reducing Condenses in
campaign part with
life. titanium
Consumes tetrachloride
coke,
chlorine
V Must be
removed by
chemical
treatment
and
distillation
Th, Ra Accumulates
in
chlorinator
brickwork,
radioactive;
causes
disposal
difficulties
______________________________________
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 metallised
REFERENCES:
patent: 1843006 (1932-01-01), Stevens st al.
patent: 2875107 (1959-02-01), Daiger
patent: 3481705 (1969-12-01), Peck et al.
patent: 3856512 (1974-12-01), Palmer et al.
patent: 4483830 (1984-11-01), Cresswell et al.
patent: 5011666 (1991-04-01), Chao et al.
patent: 5085837 (1992-02-01), Chao et al.
Bos Steven
Technological Resources Pty Ltd
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