Method for preparing artificial rutile from fine-fraction ilmenite

Abstract

The invention relates to the technical field of metallurgical industry, in particular to a method for preparing artificial rutile from fine-fraction ilmenite. The method comprises the following steps: pressing fine-fraction ilmenite serving as a raw material into a green body, sintering at high temperature in an inert atmosphere, reacting in a low-medium-temperature chlorine-containing atmosphere, crushing and screening after the reaction is finished to obtain particles, and leaching minerals by using a mixed solution consisting of a ferric chloride product generated in a chlorine reaction stage and hydrochloric acid. And normal-pressure efficient leaching of minerals can be completed, and a high-quality artificial rutile product is prepared. The whole process flow is simple, the energy consumption is lower, the reagent consumption is less, the product quality is stable, and the technical problem of preparing the high-quality artificial rutile from the fine-fraction ilmenite can be practically solved.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgical industry, and particularly to a method for preparing artificial rutile from fine-grained ilmenite. Background Art

[0002] Titanium is an important strategic metal element and has very wide applications in fields such as aerospace, infrastructure construction, biomedicine, and clean energy storage. At present, the development of the titanium industry is accelerating towards the chlorination process. The stable production condition of the chlorination process is to ensure the supply of high-quality titanium-rich raw materials for the chlorination process, because the fluidized bed chlorination process has very high requirements for the grade, particle size, and calcium and magnesium contents of the titanium-rich raw materials. The requirements for artificial rutile include a TiO2 content greater than 90 wt.%, a particle size greater than 200 mesh (generally 40 - 140 mesh), and a CaO + MgO content lower than 2.0 wt.%.

[0003] According to the survey data, ilmenite accounts for about 90% of the global consumption of titanium minerals and is the most important resource for titanium product production. Producing titanium-rich raw materials from ilmenite is also an essential process in the chlorination process. To improve the grade of titanium concentrate, it is necessary to remove silicate gangue and calcium and magnesium impurities through ball milling and beneficiation, resulting in a large amount of fine-grained ilmenite (about 20 μm). These fine-grained minerals still retain the characteristics of difficult impurity removal in rock ore resources, and the particle size cannot meet the particle size requirements of the chlorination process for raw materials.

[0004] Using the currently mature pyrometallurgical smelting process to treat low-grade fine-grained ilmenite, although large-sized titanium slag particles can be obtained through smelting, the calcium and magnesium components of the product do not meet the requirements of the chlorination process for titanium-rich materials, and a complex upgrading process is required to prepare high-titanium slag. Using the hydrochloric acid leaching process to treat low-grade ilmenite can meet the impurity removal requirements of calcium and magnesium, and the rutile product has a high titanium content, which is an ideal titanium-rich raw material for the chlorination process. However, the hydrochloric acid leaching process faces the problem of product pulverization and has relatively high requirements for the strength and properties of the leaching raw materials.

[0005] However, when using fine-grained ilmenite to prepare artificial rutile-rich titanium materials for the chlorination process, it is necessary to synchronously solve the technical problems of granulation and impurity removal. Due to the small contact angle and poor hydrophilicity of ilmenite, its pelletizing performance is poor, and it is difficult to directly pelletize with water as the pelletizing agent. Patent CN104058450A introduces a method for granulating titanium-containing materials. It preheats fine-grained ilmenite and a mixture of high-molecular hydrocarbons separately, then mixes, heats, holds for fractionation, holds for coking, breaks and screens after water cooling, and obtains titanium coke particles with a particle size of about 200 μm, which can meet the particle size requirements of the titanium-containing raw materials for the chlorination process. However, this method has relatively complex operating procedures, high carbon consumption, and the obtained titanium coke has no impurity removal process, and the raw materials for fluidized chlorination can only be obtained through the ingredient ratio of different materials. Patent CN106319246A introduces a method for granulating fine-grained titanium-rich materials. Ilmenite is treated by the hydrochloric acid method to obtain fine-grained rutile, and sodium hydroxide or potassium hydroxide and an appropriate amount of water are added as binders to granulate in an agglomeration granulator or a fluidized granulator, and then dried at a low temperature (50 - 100 °C) and calcined and solidified at a high temperature (500 - 1200 °C), and finally an artificial rutile product that meets the particle size requirements of the fluidized chlorination process is obtained. However, as a titanium-rich material, this rutile will form low-melting-point sodium and potassium salts under the conditions of fluidized chlorination, forming molten chloride salts to bond the materials, which may cause blockage of the fluidized bed layer and deterioration of the chlorination working conditions.

[0006] Based on the existing technical routes, it is still a technical problem to prepare artificial rutile for the chlorination process using fine-grained ilmenite raw materials. How to provide a method for preparing artificial rutile from fine-grained ilmenite with easily available reagents, simple process, and stable product quality has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides a method for preparing artificial rutile from fine-grained ilmenite with easily available reagents, simple process, and stable product quality, including: using fine-grained ilmenite with an average particle size of 15 - 25 μm as the raw material, pressing it into a green body and then sintering it at a high temperature in an inert atmosphere, and then reacting in an atmosphere containing chlorine below 900 °C. After the reaction ends, break and screen to obtain particles with a size of 150 - 200 μm, and mix the particles with the leaching solution to obtain artificial rutile; The temperature of the high-temperature sintering is 1150 °C - 1350 °C; the leaching solution is a mixed solution of ferric chloride and hydrochloric acid.

[0008] Preferably, the temperature of the high-temperature sintering is 1200 °C - 1350 °C.

[0009] In some embodiments, the fine-grained ilmenite is a secondary rock ore.

[0010] In some embodiments, in the fine-grained ilmenite, the content of titanium calculated as TiO2 is 42% - 55 wt.%, the content of iron calculated as Fe2O3 is 30% - 40 wt.%, the content of silicon calculated as SiO2 is 2% - 3 wt.%, the content of magnesium calculated as MgO is 2.5% - 5 wt.%, and the content of calcium calculated as CaO is 0.4% - 0.8 wt.%.

[0011] In some embodiments, the green body is cylindrical; and / or, the pressure of pressing is 250 - 450 MPa.

[0012] In some embodiments, the inert atmosphere includes nitrogen, argon or carbon dioxide.

[0013] In some embodiments, after the green body is placed into a sealed horizontal tube furnace, it is sintered at a high temperature in an inert atmosphere.

[0014] In some embodiments, the time of the high-temperature sintering is 20 - 240 min.

[0015] In some embodiments, the temperature of the reaction is 700°C - 870°C (preferably 780°C - 800°C); and / or, the volume percentage of chlorine in the atmosphere containing chlorine is 10% - 30%.

[0016] In some embodiments, the time of the reaction is 15 - 100 min.

[0017] In some embodiments, after the flue gas is collected and condensed and dissolved during the reaction process to obtain a ferric chloride solution, the leaching solution is prepared by mixing it with hydrochloric acid.

[0018] In some embodiments, the remaining tail gas is completely absorbed by an alkaline solution.

[0019] In some embodiments, the concentration of ferric chloride in the leaching solution is 5 - 30 g / L; and / or, the concentration of HCl in the leaching solution is 18 - 25 wt.%.

[0020] In some embodiments, the particles are mixed with the leaching solution, and stirred and leached at normal pressure of 90°C - 105°C, and the undissolved particles separated are artificial rutile.

[0021] In some embodiments, the time of the stirring leaching is 2 - 6 h, and the stirring speed is 100 - 400 rpm.

[0022] In some embodiments, the used leaching solution enters the spray pyrolysis recovery process as a spray pyrolysis raw material.

[0023] Preferably, no binder and carbonaceous particles are introduced in the preparation method of the present invention, and the titanium loss rate of the preparation method of the present invention is less than 15%.

[0024] In some embodiments, in the artificial rutile, the TiO2 content is greater than 89 wt.%, and / or the total content of MgO and CaO is 1 wt.% or less, and / or the CaO content is 0.12 wt.% or less, and / or the average particle size of the artificial rutile is 149 μm or more.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention uses an inert atmosphere for sintering granulation, without introducing a binder, without introducing carbonaceous particles, and without increasing impurities in the raw materials during the granulation stage; by introducing a chlorine reaction, the sintered particles are modified and pre-desulfurized in the cooling stage, utilizing the sintering heat and removing impurities in advance, reducing the consumption of acid leaching and impurity removal reagents; the sintered green body is easily broken, and the recovery rate of the target particle size is relatively high; using the iron chloride product generated in the chlorine reaction stage, a mixed solution composed of hydrochloric acid is used to leach the mineral, which can complete the atmospheric pressure high-efficiency leaching of the mineral and the preparation of the product, and the leached iron is concentrated in the same section for convenient subsequent spray pyrolysis and recycling. The overall process flow of the present invention is simple, with lower energy consumption, less reagent consumption, and stable product quality, and can effectively solve the technical problems of preparing high-quality artificial rutile from fine-grained ilmenite. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow schematic diagram of Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention fall within the scope of protection of the present invention. In the embodiments provided in this specification, those not specifying specific techniques or conditions are carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. The reagents or instruments not indicating the manufacturer are all conventional products that can be obtained through regular channels.

[0028] Example 1 This example provides a method for preparing high-quality artificial rutile from fine-grained ilmenite. The process flow schematic diagram is as Figure 1 shown, and the steps are as follows: 1. The fine-grained ilmenite is the ilmenite concentrate obtained from the ore dressing of a certain smelter, with an average particle size of 20.2 μm. The component composition is: TiO2 content 52.30 wt.%, FeO content 38.90 wt.%, SiO2 content 2.20 wt.%, MgO content 3.33 wt.%, and CaO content 0.45 wt.%.

[0029] 2. The ilmenite particles are added to a cylindrical mold and pressed into a cylindrical green body under a pressure of 300 Mpa for 3 minutes while maintaining the pressure.

[0030] 3. The green body is placed in a sealed horizontal tube furnace, and high-purity argon is filled into the furnace. The furnace body is heated to 1300 °C, held for 30 minutes, and then cooled.

[0031] 4. After the furnace body temperature is reduced to 800 °C and held, a gas is filled into the furnace. The gas volume composition is 20% chlorine gas + 80% nitrogen gas. The atmosphere is maintained for 40 minutes. After collecting the flue gas, it is dissolved in condensed water to obtain a flue gas absorption solution, and hydrochloric acid is added to make a leaching solution. The concentration of ferric chloride in the leaching solution is 15 g / L, and the HCl concentration is 20 wt.%.

[0032] 5. After the sintered matrix is cooled, particles of 150 - 200 μm are crushed and screened, with an average particle size of 166 μm. They are leached under normal pressure in the above leaching solution. The reaction temperature condition is 105 °C, the stirring speed is 100 rpm, and the leaching time is 4 h. The powder obtained by solid-liquid separation is artificial rutile.

[0033] 6. After testing, the TiO2 content in the artificial rutile is 92.66 wt.%, the MgO + CaO content is 0.87 wt.%, the CaO content is 0.1 wt.%, and the average particle size is 149 μm. The leaching solution enters the spray pyrolysis recovery process as the raw material for spray pyrolysis.

[0034] Example 2 This example provides a method for preparing high-quality artificial rutile using fine-grained ilmenite, and the steps are as follows: 1. The fine-grained ilmenite is the ilmenite concentrate obtained from the ore dressing of a certain smelter, with an average particle size of 15.3 μm. The component composition is: TiO2 content 45.2 wt.%, FeO content 40.0 wt.%, SiO2 content 2.9 wt.%, MgO content 4.70 wt.%, and CaO content 0.80 wt.%.

[0035] 2. The ilmenite particles are added to a cylindrical mold and pressed into a cylindrical green body under a pressure of 400 Mpa for 5 minutes while maintaining the pressure.

[0036] 3. The green body is placed in a sealed horizontal tube furnace, and high-purity carbon dioxide is filled into the furnace. The furnace body is heated to 1250 °C, held for 60 minutes, and then cooled.

[0037] 4. After the furnace body temperature is reduced to 850 °C, keep it warm, fill the furnace with gas, the gas volume composition is 25% chlorine gas + 75% argon gas, maintain the atmosphere for 25 min, collect the flue gas and dissolve it with condensed water to obtain the flue gas absorption liquid, add hydrochloric acid to make the leaching solution, and the ferric chloride concentration in the leaching solution is 20 g / L, and the HCl concentration is 25 wt.%.

[0038] 5. After the sintered matrix is cooled, crush and screen particles of 150 - 200 μm, with an average particle size of 173 μm, and leach it under normal pressure in the above leaching solution. The reaction temperature condition is 100 °C, the stirring speed is 150 rpm, and the leaching time is 5 h. The powder obtained by solid-liquid separation is artificial rutile.

[0039] 6. After testing, the TiO₂ content in the artificial rutile is 91.82 wt.%, the MgO + CaO content is 1 wt.%, the CaO content is 0.12 wt.%, and the average particle size is 165 μm. The leaching solution enters the spray pyrolysis recovery process as the spray pyrolysis raw material.

[0040] Example 3 This example provides a method for preparing high-quality artificial rutile from fine-grained ilmenite, and the steps are as follows: 1. The fine-grained ilmenite is the ilmenite concentrate obtained by ore dressing in a certain smelter, with an average particle size of 18.4 μm, and the component composition is: TiO₂ content 54.8 wt.%, FeO content 32.3 wt.%, SiO₂ content 2.01 wt.%, MgO content 2.53 wt.%, CaO content 0.51 wt.%.

[0041] 2. Add the ilmenite particles into a cylindrical mold, and press them into a cylindrical green body under a pressure of 350 Mpa for 5 min.

[0042] 3. Place the green body into a sealed horizontal tube furnace, fill the furnace with high-purity nitrogen gas, heat the furnace body to 1200 °C, keep it warm for 240 min and then cool it down.

[0043] 4. After the furnace body temperature is reduced to 780 °C, keep it warm, fill the furnace with gas, the gas volume composition is 15% chlorine gas + 85% nitrogen gas, maintain the atmosphere for 40 min, collect the flue gas and dissolve it with condensed water to obtain the flue gas absorption liquid, add hydrochloric acid to make the leaching solution, and the ferric chloride concentration in the leaching solution is 10 g / L, and the HCl concentration is 22 wt.%.

[0044] 5. After the sintered matrix is cooled, crush and screen particles of 150 - 200 μm, with an average particle size of 180 μm, and leach it under normal pressure in the above leaching solution. The reaction temperature condition is 105 °C, the stirring speed is 300 rpm, and the leaching time is 2 h. The powder obtained by solid-liquid separation is artificial rutile.

[0045] 6. After detection, the TiO₂ content in the synthetic rutile is 93.55 wt.%, the MgO + CaO content is 0.76 wt.%, the CaO content is 0.08 wt.%, and the average particle size is 169 μm. The leaching solution enters the spray pyrolysis recovery process as the raw material for spray pyrolysis.

[0046] Example 4 This example provides a method for preparing high-quality synthetic rutile from fine-grained ilmenite. The only difference in the steps from Example 3 is that: The sintering temperature is 1150 °C.

[0047] After detection, the TiO₂ content in the finally prepared synthetic rutile is 92.98 wt.%, the MgO + CaO content is 0.70 wt.%, the CaO content is 0.08 wt.%, and the average particle size is 149 μm.

[0048] Example 5 This example provides a method for preparing high-quality synthetic rutile from fine-grained ilmenite. The only difference in the steps from Example 3 is that: The temperature of the furnace body is reduced to 700 °C and then kept warm.

[0049] After detection, the TiO₂ content in the finally prepared synthetic rutile is 89.22 wt.%, the MgO + CaO content is 0.90 wt.%, the CaO content is 0.12 wt.%, and the average particle size is 172 μm.

[0050] Example 6 This example provides a method for preparing high-quality synthetic rutile from fine-grained ilmenite. The only difference in the steps from Example 3 is that: The gas volume composition is 25% chlorine gas + 75% nitrogen gas.

[0051] After detection, the TiO₂ content in the finally prepared synthetic rutile is 93.52 wt.%, the MgO + CaO content is 0.73 wt.%, the CaO content is 0.09 wt.%, and the average particle size is 165 μm.

[0052] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present invention, not to limit it; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing artificial rutile, characterized in that, Comprising: Using ilmenite with a fine particle size of 15 - 25 μm as the raw material, pressing it into a green body and then sintering it at a high temperature in an inert atmosphere, followed by reacting in an atmosphere containing chlorine below 900 °C. After the reaction, it is crushed and screened to obtain particles of 150 - 200 μm, and the particles are mixed with the leaching solution to prepare synthetic rutile. The temperature of the high-temperature sintering is 1150 °C - 1350 °C; the leaching solution is a mixed solution of ferric chloride and hydrochloric acid.

2. The preparation method according to claim 1, characterized in that, The green body is cylindrical; and / or, the pressure of the pressing is 250 - 450 MPa.

3. The preparation method according to claim 1, characterized in that, The inert atmosphere includes nitrogen, argon or carbon dioxide.

4. The preparation method according to claim 1, characterized in that The temperature of the reaction is 700 °C - 870 °C; and / or, the volume percentage of chlorine in the atmosphere containing chlorine is 10% - 30%.

5. The preparation method according to claim 1, characterized in that, During the reaction process, the flue gas is collected, condensed and dissolved to obtain a ferric chloride solution, which is then mixed with hydrochloric acid to prepare the leaching solution.

6. The preparation method according to claim 5, characterized in that, The concentration of ferric chloride in the leaching solution is 5 - 30 g / L; and / or, the concentration of HCl in the leaching solution is 18 - 25 wt.%.

7. The preparation method according to claim 1, characterized in that, The particles are mixed with the leaching solution and stirred for leaching at normal pressure of 90 °C - 105 °C, and the undissolved particles separated are the synthetic rutile.

8. The preparation method according to claim 7, characterized in that, The used leaching solution enters the spray pyrolysis recovery process as the raw material for spray pyrolysis.

9. The preparation method according to claim 1, characterized in that, No binder and carbonaceous particles are introduced in the preparation method.

10. The preparation method according to any one of claims 1 to 9, characterized in that, In the synthetic rutile, the TiO₂ content is greater than 89 wt.%, and / or, the total content of MgO and CaO is 1 wt.% or less, and / or, the content of CaO is 0.12 wt.% or less, and / or, the average particle size of the synthetic rutile is 149 μm or more.

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