Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group ivb metal
Reexamination Certificate
1999-11-17
2002-12-31
Bos, Steven (Department: 1754)
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group ivb metal
C423S076000, C423S082000
Reexamination Certificate
active
06500396
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to methods for the separation of titanium from ore, especially iron-bearing ore e.g. ilmenite ore. In embodiments of the invention, the method relates to the recovery of titanium tetrahalides, especially titanium tetrachloride from solutions. In further embodiments, the invention relates to recovery of titanium metal from such ore.
BACKGROUND OF THE INVENTION
Many processes are known for the recovery of titanium dioxide from ores. Ilmenite, which contains mainly titanium oxide and iron oxide values, often is employed in such processes. The majority of processes for the recovery of titanium dioxide from ores involve digestion of the ore in a mineral acid, such as hydrochloric acid or sulphuric acid, to remove at least the titanium values from the ore. In such processes, however, the purity of the titanium dioxide produced is about 90-95%, and hence further purification procedures may be required to produce a pigment grade product, which adds considerably to the cost. Many of the further purification procedures involve techniques that are environmentally unacceptable without extensive procedures to treat various solutions and solids obtained. Such treatment processes tend to be costly.
Processes for the recovery of titanium dioxide from ilmenite in high purity and high yield are known. One such process is described in U.S. Pat. No. 3,903,239 of S. A. Berkovich, which discloses a process which comprises contacting ilmenite, or a concentrate thereof, in particulate form with concentrated hydrochloric acid at a temperature of about 15-30° C. to solubilize and leach from the ore at least 80%, preferably at least 95%, of the iron and titanium values. The leaching operation may be carried out over an extended period of time, typically from 3-25 days, depending on the technique employed and the quantity of iron values to be recovered. Leaching techniques include counter-current flow or the use of closed cycle loops in which hydrochloric acid is continuously passed through a bed of the ore. The leaching operation is exothermic, and the reactants are maintained in a temperature range of 15-30° C. by cooling, if necessary.
The ilmenite or similar ore used in the process may be treated as such or may be beneficiated to form a concentrate in any desired manner. Ilmenite generally contains TiO
2
.FeO with varying amounts of Fe
2
O
3
and gangue materials, usually silicates, alumina, lime and magnesium. Beneficiation may be employed when the ore is of low TiO
2
content.
The ore or concentrate may be pre-treated prior to contact with the concentrated hydrochloric acid to increase the rate of dissolution of the titanium and iron values during the leaching step. Such pre-treatment may include an initial oxidation at elevated temperature, such as from 600-1000° C., in the presence of air and/or oxygen to split the TiO
2
.FeO followed by reduction of at least part of the iron oxide with carbon or carbon monoxide. This is a smelting step, with slag from the smelting step being fed to the leaching step and pig iron being marketed.
Subsequent to the leaching step, it is necessary to convert any ferric iron in the solution to ferrous iron, which is typically achieved by reduction of the ferric iron in the leach liquor with a gaseous reducing agent e.g. sulphur dioxide. The conversion of ferric iron to ferrous iron in this manner is essential in view of the affinity of titanium dioxide for ferric iron and the difficulty in separating ferric iron from titanium dioxide.
The solution of titanium chlorides and ferrous chloride which is thus obtained, and which may contain minor quantities of gangue metal chlorides, typically calcium and magnesium materials, is then mixed with water to cause hydrolysis of the titanium chlorides. A seeding amount, generally about 1-2%, by weight of the titanium oxyhydrate to be precipitated (TiO
2.3
H
2
O) is included in the mixture. Titanium oxyhydrate precipitates from the mixture. The hydrolysis is carried out using a quantity of water at least sufficient to precipitate substantially all of the titanium values from the solution but insufficient to cause precipitation of other metal oxides or hydroxides. The titanium oxyhydrate that is precipitated from the mother liquor is then washed substantially free of entrained mother liquor and dried. The washed precipitate is converted at elevated temperature, typically 700-1000° C., in the presence of air and/or oxygen into the anatase or rutile form of titanium dioxide.
Alternative methods that require less treatment of solution and solids to ensure environmental acceptance and/or are less expensive in achieving environmental acceptance, as well as producing titanium and other products of high value e.g. high purity, are required.
SUMMARY OF THE INVENTION
A method for the separation of titanium, and for production of titanium metal, from titanium-bearing ore that involves a reduced number of steps has now been found.
Accordingly, one aspect of the present invention provides a method for the separation of iron values from titanium-bearing ore, comprising the steps of:
a) leaching said ore, or a concentrate thereof, with an aqueous solution of a hydrogen halide;
b) separating solids from the leach solution obtained in (a), to provide a leachate solution;
c) subjecting the leachate solution to extraction with an immiscible organic phase that selectively extracts iron values into said organic phase, titanium values in the leachate solution selectively remaining in the aqueous leachate solution.
Another aspect of the invention provides a method for the production of titanium metal from titanium-bearing ore, comprising the steps of:
a) leaching said ore or a concentrate thereof with an aqueous solution of a hydrogen halide;
b) separating solids from the leach solution obtained in (a), to provide a leachate solution;
c) subjecting the leachate solution to extraction with an immiscible organic phase having a boiling point that differs from the boiling point of the titanium halide in the leachate by an amount that permits separation thereof by fractional distillation, said organic phase being stable with respect to the titanium halide; and
d) stripping titanium halide from the organic phase obtained in step (c) by heating to volatilize the titanium halide and effect separation from the organic phase.
A further aspect of the invention provides a method of separating a titanium halide from a concentrated aqueous solution of the titanium halide, said titanium halide being in a concentration such that the titanium halide is substantially stable in said aqueous solution, comprising:
a) admixing said aqueous solution with an organic phase having a boiling point that differs from the boiling point of the titanium halide by an amount that permits separation thereof by fractional distillation;
b) separating the organic phase so obtained from the aqueous solution; and
c) heating the organic phase and stripping titanium halide therefrom.
Yet another aspect of the invention provides a method for the separation of titanium from a titanium-bearing ore, said ore containing iron, comprising the steps of:
a) leaching said ore, or a concentrate thereof, with an aqueous solution of a hydrogen halide in the presence of an oxidising agent; and
b) effecting a separation of titanium dioxide obtained in step (a) from said solution.
A further aspect of the invention provides a method of forming a titania-rich slag from a titanium-bearing ore that contains iron, comprising the steps of:
a) calcining the ore under oxidizing conditions to eliminate sulphur from said ore, said calcining being carried out at a temperature of at least 1200° C.;
b) subjecting the hot calcined ore of step (a) to reducing conditions in the presence of CO;
c) transferring the hot reduced calcined ore obtained in step (b) to a smelting step;
controlling the reducing conditions and the smelting step to obtain pig iron and a titania-rich slag with a predetermined iron content.
Another aspect of the invention provides a method of forming a
de Laat Robert Joseph
Lakshmanan Vaikuntam Iyer
Rishea Marc Murray
Sridhar Ramamritham
Bos Steven
Caesar Rivise Bernstein Cohen & Pokotilow Ltd.
LandOfFree
Separation of titanium halides from aqueous solutions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Separation of titanium halides from aqueous solutions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Separation of titanium halides from aqueous solutions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2986625