A method of processing titanium containing mineral raw materials

 

(57) Abstract:

The invention relates to the production of highly pure titanium dioxide, used as a pigment in the composition of enamels, paints, compounds of heat-resistant glass, ceramics, piezomaterials and in other industries. The source of such raw materials is subjected to fluorination by hydrovhloride ammonia at a molar ratio of 1:(4-5), then perftorirovannye product is heated to separate the sublimation of volatile formoney complex compounds of titanium from the non-volatile iron compounds with subsequent condensation formoney of titanium compounds. Condensed Vashon is subjected to heat treatment in two stages with obtaining titanium dioxide. Sludge containing iron, processed to obtain iron oxide or metallic iron, alloy present in the raw material impurities, for use as a pigment (ochre), heat-resistant anti-corrosion coatings and powder metallurgy. The method allows to obtain titanium dioxide of the anatase modification is white and increase the efficiency of the process, and get additional marketable product is finely dispersed silicon dioxide of high purity. 5 C.p. f-crystals.

The main volume produced at the moment of titanium dioxide produced by decomposition of ilmenite concentrate with sulfuric acid (Dobrovolsky, I. P. Chemistry and technology of oxide of titanium compounds. Sverdlovsk: Ural branch of the USSR Academy of Sciences, 1988). The disadvantages of this method are its high cost, increased danger of working with a strong acid, ecologicall and multistage.

More efficient (compared to sulfuric acid) opening ilmenite raw material fluorine-containing reagents.

There is a method of processing titanium containing minerals, including fluoridation his byflorida ammonium (hereinafter - hydrovhloride ammonium, NH4HF2the temperature value 50-190oC for 2-72 h with the formation of formoney salts of titanium, silicon and iron, heating protonirovannoi mass at a temperature of 350-650oC for 0.5-10 hours to extract by sublimation of volatile formoney complex compounds of titanium and silicon and their subsequent condensation in the temperature range 270-25oC at sight formoney complex salts and heating wasgone to 500-800oC in the presence of water vapor (pyrohydrolysis) for 3-5 h with the formation of TiO2. To obtain fine silica Vashon fluorosilicate preparation of ammonia (NH4)2SiF6treated with ammonia water. To obtain ultrafine iron oxide sludge remaining after phase separation, is heated to a temperature 800-840oC in the presence of water vapor within 3-5 hours (U.S. Pat. RF N 2058408, publ. 20.04.96).

The method allows to obtain titanium dioxide of the anatase modification of high purity and is safe and environmentally sound, provides the wasteless production with regeneration and return of the reagents in the loop.

The disadvantage of this method is that the target product is titanium dioxide - has a yellow or cream color. This is because dioxide, UP> contains a mixture of titanium lower degrees of oxidation.

In addition, in the process enlarged experimental validation of the method was established that the ratio of hydrovhloride ammonium to source raw materials at the stage of fluorination equal 95-117% of the required stoichiometric (molar ratio 1: 6), greater than sufficient for fluorination and subsequent full extraction of titanium tetrafluoride (TiF4and its condensation in the form of formoney salts. Inflated the number of GDFA causes, in addition to excessive reagent consumption, the significant duration of fluoridation (up to 72 hours), large amounts of metal and formed immixture gas phase, which reduces the efficiency of the method and complicates it.

It was also found that the condensation of voshon near the maximum value of the temperature interval (270oC) leads to the partial volatilization TiF4from wasgone and coprecipitation with NH4HF2in the cold zone. In this case, to return GDFA in the cycle requires prior separation of the reactants, which also complicates the process.

Object of the invention is the production of high-purity titanium dioxide with high degree of whiteness and increase S="ptx2">

The problem is solved by the proposed method for processing titanium containing minerals, including fluoridation his hydrovhloride ammonium (NH4HF2) at a temperature of 50-190oC with the formation of formoney compounds, subsequent heating protonirovannoi mass at a temperature of 350-650oC to maximize recovery by sublimation of volatile formoney complex salts and their subsequent condensation in the form of formoney complex salts and their heat treatment to obtain the desired products, which, in contrast to the known method, the fluoridation source of raw materials hydrovhloride ammonium carried out at a molar ratio of raw material to GDFA equal to 1: (4-5), the condensation is carried out in the temperature range from 230oC to room, and the heat treatment of the condensed formoney complex salts with obtaining titanium dioxide is performed on the air in two stages, with the first stage heat lead from room temperature to 370-400oC obtaining TiO2intensive yellow color, and in the second stage, the resulting product is annealed to a temperature of 750oC obtaining TiO2white.

The sludge remaining after sublimation of the volatile ftpe need to get advanced in the processing of such raw material fine silica (if present in the feedstock), retrieval is carried out in accordance with the known method.

The method is as follows.

The original titanium - and iron-containing material, for example, ilmenite, titanomagnetite, mixed with crystal hydrovhloride ammonia in a molar ratio of 1:(4-5), respectively.

The selected ratio provides for fluoridation education less saturated ammonium fluoride ammonium complex salts compared with (NH4)2TiF6and (NH4)3FeF6.

The fluorination is carried out with stirring in a reactor lined with Teflon, before the termination of the vapor emissions, which indicates complete reaction. Weight passing the fluorination reaction is controlled by the composition of the products of the fluorination method of x-ray phase analysis (XRD). It is experimentally shown that the duration of fluoridation materials depends on the process temperature, particle size distribution and in the range of 0.5 to 6 hours.

Fluoridation is accompanied by mass loss in the form of ammonia water in the amount of 22-23% in the calculated decrease of the mass of 23.2%.

We offer the molar ratio of raw materials to GDFA equal to 1:(4-5), is sufficient for carrying out fluorination with education connerney condensation of titanium in wasgone as formoney salts, because the number of NH4F for this is insufficient.

Converted into the gas phase ammonia is cooled, collected and further used for absorption of HF containing acid vapors released during the heat treatment of voshon to obtain circulating GDF or to obtain silicon dioxide.

Then perftorirovannye mass is heated to a temperature of 350-650oC for the separation of titanium from iron similar to a known method.

Titanium salt in thermal decomposition to TiF4partially passes the stage of oxalate water vapor with the formation of (NH4)2TiOF4and TiOF2.

Released during oxalate, and the dissociation of the ammonia hydrogen fluoride is involved in the transport reaction transfer oksihlorid titanium TiOF2in the gas phase to condense it, along with (NH4)2TiF6in the form of (NH4)2TiOF4in sublimates.

Decomposition formoney salts of titanium and iron when heated, accompanied by redox processes of thermal dissociation of ammonia to nitrogen and hydrogen, which restores trivalent iron to divalent (FeF2).

The decomposition of the left or stilografica reactor and Teflon capacitors sluice, in which are the condensation products of fluorination.

Condensation of the gaseous products of fluorination in the condensation zone of voshon occurs in the temperature range from 230oC to room, while the condensation of the gaseous products of the fluorination of titanium is in the range of temperatures 230-210oC, and the condensation of hydrovhloride ammonia in the temperature range from 50oC to room.

When the temperature in the condensation zone above 230oC there is partial loss of the Titan with his transition into the condensation zone, GDFA.

The study of the dependence of volatility TiF4temperature in the range of 200-700oC showed that at 270oC loss of titanium can be up to 10% due to the fact that TiF4partially flows into the condensation zone, GDFA and deposited there. The beginning of this process is already apparent at a temperature of 240oC.

Condensed GDFA can then be recycled for use on-stage fluorination.

Kinetic studies revealed that the duration of sublimation is not more than 5 hours. Control is carried out by chemical analysis, determining the residual titanium.

Then sonde is carried out in air in two stages, moreover, in the first stage heating of the lead from room temperature to 370-400oC, and the second stage up to 750oC. Formed on the first heating stage is bad recrystallizing TiO2the anatase modification is yellow or cream color. Subsequent annealing at a temperature of up to 750oC leads to the production of TiO2the anatase modification with an ordered structure having a white color. Increasing the temperature above 750oC is not economically feasible.

The implementation of heat treatment wasgone obtaining TiO2in the anatase form in two stages provides a gradual substitution of fluorine for oxygen and prevents the inherent well-known method of thermal decomposition of (NH4)2TiOF4that high speed is in a narrow temperature interval 470-480oC, which creates a large local concentration of hydrogen in origemail mass wasgone and partially restores Ti4+to Ti3+and Ti2+giving color to the final product.

In contrast to the known method, carrying out heat treatment of voshon in the proposed conditions provides not only get a white TiO2but you can eliminate from pyrohydrolysis and the turnover.

Remaining after phase separation at 350-650oC slurry containing non-volatile fluorides of iron, processed for additional commercial products based on iron.

To obtain ultrafine iron oxide sludge is heated to a temperature 800-840oC in the presence of water vapor in 3-5 hours. As a result of hydrolysis of the fluoride iron goes into the oxide and is formed ultra-fine powder of iron oxide doped with impurities contained in the original raw materials.

To obtain metallic iron powder slurry is heated to 560-580oC in the presence of hydrogen in 3-5 hours. In the recovery of fluoride iron goes into the metal, and is formed of metallic iron doped contained in the feedstock impurities (V, Cr, Ti, Ni, Co).

Formed during hydrolysis and recovery FeF2hydrogen fluoride is collected in an ammonia solution. After evaporation of the solution and crystallization of GDFA recent return to the stage fluorination.

The resulting products of iron can be used in powder metallurgy, as well as pigment (ochre) to obtain valuable artistic paints, thermosta raw materials can be obtained silicon dioxide as follows. When heated protonirovannoi mass to 350-650oC formoney silicon compounds are extracted simultaneously with feromonami the titanium compounds separated from the slurry containing non-volatile fluorides. This formoney compounds of silicon and titanium are condensed in the condenser-collector. Subsequent heat treatment of voshon leads to the separation of silicon from titanium due to the sublimation of ammonium fluorosilicate preparation, which does not decompose and is not hydrolyzed in the air. Assembled (NH4)2SiF6treated with ammonia water and get fine SiO2high purity, which can be used as filler in medical and cosmetic products, in the production of rubber, as well as a biocidal preparation of high activity.

Thus, the proposed method allows to obtain as the main product of high purity anatase titanium dioxide (purity not less than 99.95%) with the content of coloring impurities (Fe, Ni, Cr, Mn) is not more than 10-4wt.%, possessing a high degree of whiteness, and as an added commodity products - ultra-fine powders of iron oxide or metallic iron and finely dispersed silicon dioxide.

Denmark raw materials at 30-33% and accordingly, decrease as the duration of this process in 2,5-3 times, and the reaction (process) volumes; exception by lowering the upper temperature threshold condensation wasgone losses titanium by separation of titanium salts, GDFA and, therefore, additional costs for their separation.

The possibility of regeneration and return to the cycle of a basic reagent, GDF during the whole technological process in conjunction with the reduction of GDFA on stage opening makes way more economical.

These benefits increase the efficiency of the method of processing titanium containing minerals and are a new technical result that can be obtained from its implementation.

The ability of the method to achieve the technical result is also confirmed by the following examples.

Example 1. A portion of ilmenite concentrate (Arianism field, Primorsky Krai), containing, by weight. %: TiO2- 42,50; Fe2O3- 13,42; FeO - 29.67 Per; SiO2- 5,80; Al2O3- 2,00; MgO - 3,35; CaO - 1,50; MnO - 0,49; Cr2O3to 0.19, a weight of 1 kg was mixed with 1.5 kg of hydrovhloride ammonium (NH4HF2oC to stop vapor emissions. Time fluorination was 4 hours. Resulting from the fluorination product weight 1,95 kg was a crisp white product with a small amount of dark grains (inclusions). Fluoridation was accompanied by mass loss in the form of ammonia water in the amount of 22.0%. The estimated decline in the mass of 23.2%. According to XRD, the product was a mixture of complex salts of titanium and iron.

Then perftorirovannye product in quantities of 0.5 kg was heated in a Nickel reactor at 600oC for 5 hours.

Collected in the condenser-collector white product weight 0,36 kg was combined loshonom salts of titanium and hydrovhloride ammonium.

Non-volatile residue brown weight 0.14 kg represented FeF2that corresponds to the extraction of titanium by 72% (98% of theoretically possible).

Received in the divided temperature zones Vashon represented in the area around 230oC mixture of herocomplex titanium (NH4)2TiF6and (NH4)2TiOF4(the content of TiO2- 43,7%) weight 0,305 kg, and in the area of about 20oC - hydrolittoral ammonium NH4HF2mass 0,055 kg

Vashon weight 0,10 kg placed the round was raised to 750oC. the obtained white product weight 0,433 kg, the chemical composition of TiO2the structure is anatase. Removing TiO2at 99.1%, product purity is 99.95 percent.

The sludge remaining after extraction by the sublimation of volatile compounds of titanium, weight 0.14 kg were subjected to pyrohydrolysis in the Nickel reactor at 800oC and rate of vapor flow of 0.5 l/hour. Time pyrohydrolysis - 3.5 hours. The resulting brown product weight 0.118 kg, corresponds to the chemical formula Fe2O3. The output rate of 99.0%.

Example 2. The process in obtaining TiO2conducted in accordance with the conditions of example 1, except the molar relationship of the concentrate to hydrovhloride ammonium, which was 1:5.

Technological parameters of the method and quality of the obtained titanium dioxide correspond to the parameters of example 1.

The sludge after removal by sublimation of volatile compounds titanium weight 0.14 kg was subjected to reduction with hydrogen in the Nickel reactor at a temperature of 560oC at a feed rate of hydrogen 0.14 l/min for 4 hours. The resulting product color gray weight 0.08 kg corresponds to the chemical formula Fe. Output 95,0%.

1. A method of processing titanium containing mineral is raptureready mass at 350 - 650oC before extraction by sublimation of volatile formoney complex compounds and their subsequent condensation and heat treatment of the condensed formoney complex salts with obtaining the target product, characterized in that the fluoridation source of raw materials hydrovhloride ammonium carried out at a molar ratio of raw material to GDFA equal to 1 : (4 - 5), the condensation is carried out in the temperature range from 230oC to room, and the heat treatment of the condensed formoney complex salts with obtaining titanium dioxide is performed on the air in two stages, with the first stage heat lead from room temperature to 370 - 400oC, and the second stage up to 750oC.

2. The method according to p. 1, characterized in that for obtaining ultrafine iron oxide sludge remaining after sublimation of volatile formoney complex salts, heated to 800 - 840oC in the presence of water vapor for 3 to 5 hours

3. The method according to p. 1, characterized in that to obtain a powder of metallic iron sludge remaining after sublimation of volatile formoney complex salts, restore hydrogen at 560 - 580oC for 3 - 5 hours

4. The method according to p. 1, characterized in that one.

5. The method according to p. 1, characterized in that the gas phase fluorination in the gas phase ammonia is used to absorb containing the hydrogen fluoride vapor generated at the stage of heat treatment wasgone or to obtain silicon dioxide.

6. The method according to any of paragraphs.1 to 5, characterized in that hydrolittoral ammonium generated at all stages of the way, collect and return to the cycle phase fluorination.

 

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