RU2365647C1 - Method of processing of raw materials containing titanium - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to a method of processing of the raw materials containing titanium and can be used to obtain fine titanium dioxide and ferric oxide base powders. The method involves fluorination of the raw materials by means of sintering with fluoride reagent, heat treatment of the fluorinated mass in order to separate the fluorination products by sublimation, pyrohydrolysis of the residue left after sublimation to obtain ferric oxide. Fluorination uses ammonium fluoride as the fluoride reagent, ammonium bifluoride or their mixture and fluorination is performed at 110-240°C for 0.5-5 hours in vacuum or in inert gas. Heat treatment of the fluorinated mass at sublimation is performed at 300-600°C. The sublimation products are trapped with water obtaining a solution of ammonium fluorotitanate and hydrated titanium dioxide is precipitated with an aqueous solution of ammonia. After that the sediment is filtered from the solution of ammonium fluoride and heat treated to obtain anhydrous titanium dioxide. Pyrohydrolysis of the residue after sublimation is performed at 300-650°C for 0.5-3 hours.

EFFECT: increased degree of titanium extraction as fine powder and reduced energy intensity of the process.

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Description

The invention relates to the processing of titanium-containing raw materials and can be used to obtain fine powders based on titanium dioxide and iron oxide.

Known liquid-phase methods for the separation of iron and titanium, including the method [RF Patent No. 2144504, C01G 23/04, 49/10 Method for the separation of iron and titanium], in which titanium-containing concentrates are opened with hydrofluoric acid. Iron is precipitated with ammonia solution at pH 4-8. Titanium remains in solution. The addition of soluble sulfides to the filtrate after precipitation of iron fluorides can increase the degree of iron recovery to 99.95%. The main disadvantage of this method is an admixture of iron (not less than 0.05 wt.%) In the final titanium dioxide, which significantly impairs the quality of the titanium pigment.

A known method of opening ilmenite with fluorine and hydrogen fluoride [L.P. Rikhvanov, S.S. Kropanin, S.A. Babenko, A.I. Soloviev, V. M. Sovetov, T. Yu. Usova, M. A. Polyakova . Zircon-ilmenite placer deposits - as a potential source of development of the West Siberian region. - Kemerovo 2001., 224 p.]. In this method, titanium and iron fluorides are formed, the separation of which can be carried out by sublimation of titanium tetrafluoride (sublimation temperature TiF ₄ = 280 ° C). This method allows for deep cleaning of the titanium component of ilmenite. The disadvantage of this method is the high cost of fluorine and the lack of its regeneration.

As a prototype, the method was selected [RF Patent No. 2058408, C22B 34/12 Method for processing titanium-containing mineral raw materials], including fluorination of the feedstock by sintering with ammonium hydrodifluoride (NH ₄ HF ₂ ) in a ratio of 95-117 wt.% From stoichiometric, heat treatment profiled mass, followed by separation of the fluorination products by sublimation, pyrohydrolysis of the fluoroammonium complex of titanium to obtain titanium dioxide. The sludge remaining after sublimation of titanium is hydrolyzed at 800–840 ° С to obtain “doped” iron oxide. The disadvantage of this method is the low degree of separation of titanium from the feedstock. During the pyrohydrolysis of titanium fluorides, titanium dioxide of rutile modification is formed in the form of needle single crystals, which does not allow using this method to obtain pigment grades.

The objective of the invention is to increase the degree of release of titanium, to reduce the energy intensity of the processing of ilmenite (the main mineral of titanium) to pigment titanium dioxide.

The solution of this problem is achieved by using ammonium fluorides for opening titanium-containing raw materials followed by sublimation of titanium, precipitation of hydrated titanium dioxide from a solution containing titanium tetrafluoride and ammonium fluoride. Under the influence of superheated water vapor, the residue is converted into an iron oxide pigment. The proposed method is characterized in that for opening use ammonium fluoride (NH ₄ F), ammonium hydrodifluoride (NH ₄ HF ₂ ) and their mixture, including technical ammonium fluoride (NH ₄ F - 25% and NH ₄ HF ₂ - 75% ), which is formed by the evaporation of aqueous solutions of NH ₄ F [Chemical Encyclopedia. In 5 volumes. T.1 / Ed. Col .: Knunyants I.L. (Ch. ed.) and others. - M .: Sov. encycl., 1988. - 623 p., S.155]. The fluorinating agent is taken with an excess of 1-50 wt.% From the stoichiometric ratio. The mixture of starting materials is heated to 110-240 ° C and maintained in this temperature range (in the melt of the fluorinating agent) for 0.5-5 hours, which is necessary for more complete fluorination (the melting point of the eutectic NH ₄ F with NH ₄ HF ₂ 109 , 3 ° С, boiling point (with decomposition) NH ₄ HF ₂ 238 ° C [Chemical encyclopedia. In 5 volumes. Vol. 1 / Rev. Col .: Knunyants I. L. (chap. Ed.), Etc. - M .: Sov. Encycl., 1988. - 623 p., S.155]). Then the profluorinated mixture is heated at 300-600 ° C for 0.5-3 hours, while titanium is sublimated, the residue is subjected to pyrohydrolysis at 300-650 ° C to form Fe ₂ O ₃ . The processes of opening and sublimation of titanium must be carried out without access of air (in the atmosphere of reaction products) or in a stream of inert gas, which increases the completeness of fluorination and the degree of release (sublimation) of titanium.

The method is as follows.

Example.

Ilmenite concentrate is fluorinated in the molten ammonium fluoride (taken in excess), while the reaction proceeds:

FeTiO ₃ + 12NH ₄ F = (NH ₄ ) ₃ TiF ₇ + (NH ₄ ) ₃ FeF ₅ + 6NH ₃ ↑ + 3H ₂ O ↑;

up to 200 ° C, the gas phase is sent to the regeneration of ammonia water. In the case of ammonium hydrodifluoride, the reaction proceeds:

FeTiO ₃ + 6NH ₄ HF ₂ = (NH ₄ ) ₃ TiF ₇ + (NH ₄ ) ₃ FeF ₅ + 3H ₂ O ↑.

In the case of using a technical mixture of a fluorinating reagent (NH ₄ F - 25% and NH ₄ НF ₂ - 75% or (NH ₄ ) ₄ H ₃ F ₇ ), which is obtained by evaporating aqueous solutions of ammonium fluoride, the decomposition of ilmenite is described by the following reaction:

7FeTiO ₃ +12 (NH ₄ ) ₄ H ₃ F ₇ = 7 (NH ₄ ) ₃ TiF ₇ +7 (NH ₄ ) ₃ FeF ₅ + 6NH ₃ ↑ + 21H ₂ O ↑.

Then, after fluorination, the mixture is heated to decompose the fluoroammonium complexes and sublimation separation of titanium, and up to 300 ° C the gas phase, consisting of ammonia and hydrogen fluoride, is sent to regenerate the fluorinating agent. In the atmosphere of reaction products, the degree of titanium extraction reaches 93%, and in an inert gas stream, up to 99%. The increase in the degree of extraction of titanium in an inert gas stream is explained by a more complete removal of water vapor from the reaction volume. With a lack of a fluorinating agent, as well as in the presence of water vapor and oxygen, partial formation of ammonium oxyfluorotitanates ((NH ₄ ) ₂ TiOF ₄ , NH ₄ TiOF ₃ ) occurs, which upon thermal decomposition forms titanium oxyfluoride (TiOF ₂ ). Titanium oxydifluoride above 550 ° C decomposes into TiF ₄ and TiO ₂ . To intensify the processing of titanium-containing raw materials, the reaction mixture is mixed.

When the fluorination products are heated above 300 ° C, sublimation of titanium occurs. As a result of the capture of exhaust gases by water, a solution of ammonium fluorotitanate of the composition (NH ₄ ) _n TiF _{4 + n} (n = 0 ... 2) is obtained. Hydrated titanium dioxide is precipitated by the action of ammonia water on the resulting solution; ammonium fluoride remains in the solution. After separation of the precipitate by filtration, the precipitate is subjected to heat treatment to anhydrous titanium dioxide. The mother liquor is sent to the regeneration of the fluorinating agent.

After sublimation separation of titanium, the remainder of the mixture is subjected to oxidative pyrohydrolysis above 300 ° C (interaction with superheated water vapor and air oxygen) with the formation of iron oxide (III).

As a result of the above operations, finely dispersed titanium dioxide with an iron content of less than 0.01 wt.% (In terms of Fe ₂ O ₃ ) is obtained. Processing ilmenite concentrate with ammonium fluorides allows (tested experimentally at the concentrate of the Tugan deposit of the Tomsk region) to separate the titanium component by sublimation by 98-99% (in an argon stream), which allows the residue to be used to obtain iron oxide pigment. The content of titanium dioxide in the iron oxide pigment is not more than 3 wt.%, Which allows it to be used to obtain red and yellow pigments. Thus, the claimed method of processing titanium-containing raw materials can improve the purity and degree of release of titanium.

Claims (1)

A method for processing titanium-containing raw materials, including fluorination of raw materials by sintering with a fluoride reagent, heat treatment of a fluorinated mass to separate fluorination products by sublimation, pyrohydrolysis of the residue after sublimation to obtain iron oxide, characterized in that ammonium fluoride, ammonium hydrodifluoride or fluoride are used as fluoride reagent their mixture and conduct it at 110-240 ° C for 0.5-5 hours without access of air or in an inert gas stream, heat treatment of the fluorinated mass upon sublimation ut at a temperature of 300-600 ° C, sublimation products are captured with water to obtain a solution of ammonium fluorotitanate and precipitated hydrated titanium dioxide with an aqueous solution of ammonia, followed by filtering the precipitate from a solution of ammonium fluoride and heat treatment of the precipitate to obtain anhydrous titanium dioxide, pyrohydrolysis of the residue after sublimation is carried out at 300-650 ° C for 0.5-3 hours