Method for preparing artificial rutile by using reduced ilmenite

Abstract

The invention introduces a method for preparing artificial rutile by using reduced ilmenite, which comprises the following steps: S1, adding reduced ilmenite into a corrosion tank, introducing oxidizing gas to carry out corrosion reaction, and washing and separating the reaction product through a cyclone and a high-frequency sieve to obtain primary artificial rutile and hydrated iron oxide slurry; s2, carrying out filter pressing on the hydrated iron oxide slurry obtained in the step S1 by using a filter press, and preparing refined iron oxide from the obtained iron oxide slurry; s3, the primary artificial rutile obtained in the step S1 is washed and then subjected to a hydrochloric acid leaching reaction, a mixed material obtained after acid leaching enters a thickener, and supernatant returns to prepare an acid leaching solution; feeding lower-layer ore grains into a belt filter for deacidification and washing; and S4, drying the cleaned primary artificial rutile obtained in the step S3 through a drying cylinder to obtain the finished artificial rutile. Industrial hydrochloric acid is used as a rusting agent, and compared with ammonium chloride, the product Fe (OH) 3 can be separated more easily. Oxidizing gas used for rusting is mixed gas of air and pure oxygen, and the mixing proportion of the air and the pure oxygen can be dynamically adjusted according to different rusting raw materials, so that the reaction condition is in an optimal state. In the corrosion and acid leaching processes, the recycling efficiency of the liquid raw material is extremely high, and the prepared artificial rutile meets the requirements of a chlorination process titanium dioxide raw material. The whole process flow is reasonable in design, simple to operate, free of environmental pollution and easy for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of titanium resource utilization, and particularly relates to a method for preparing synthetic rutile by using reduced ilmenite. Background Art

[0002] Titanium dioxide, as a high-quality white pigment, is widely used in fields such as coatings, plastics, and printing inks. The chlorination method is one of the important processes for producing titanium dioxide, and its product, chlorinated titanium dioxide, belongs to high-end titanium products. However, the chlorination method for producing titanium dioxide has relatively high requirements for chlorinable raw materials (TiO2>90%, MgO+CaO<1.5%, and other impurities as low as possible). At present, synthetic rutile, as a high-quality titanium-rich material, is one of the important raw materials for producing titanium dioxide by the chlorination method, and its own efficient and high-quality preparation process is also an important part of the development of the titanium industry. Therefore, developing a method for preparing synthetic rutile by using reduced ilmenite to provide high-quality raw materials for the chlorination method for producing titanium dioxide is of great significance for the efficient utilization of titanium resources. In view of this, the present invention is specifically proposed. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing synthetic rutile by using reduced ilmenite to solve the deficiencies of the prior art. This process has a high resource utilization rate, a reasonable process flow design, and is easy to operate.

[0004] The present invention provides the following technical solutions: A method for preparing synthetic rutile by using reduced ilmenite, comprising the following steps:

[0005] S1. Add the reduced ilmenite into a rusting tank, introduce an oxidizing gas for rusting reaction, and after the reaction product passes through a cyclone, a high-frequency screen, and washing and separation, obtain primary synthetic rutile and hydrated iron oxide slurry.

[0006] S2. Use a filter press to filter the hydrated iron oxide slurry obtained in step S1 to obtain iron oxide mud for manufacturing refined iron oxide.

[0007] S3. Wash the primary synthetic rutile obtained in step S1 and then carry out a hydrochloric acid leaching reaction. After acid leaching, the mixed material enters a thickener, and the upper layer liquid is returned to prepare the acid leaching solution; the lower layer ore particles are sent to a belt filter for deacidification and washing.

[0008] S4. Dry the washed synthetic rutile obtained in step S3 through a drying cylinder to obtain the finished synthetic rutile.

[0009] Preferably, the metallization rate of the reduced ilmenite used in the process is between 90% and 95%.

[0010] Preferably, in step S1, the rusting solution generally contains about 0.5 - 2.5 wt% chloride ions and is prepared from hydrochloric acid, the stock solution with a relatively high chloride ion concentration before washing after rusting and pickling, and water.

[0011] Preferably, in step S1, the mass concentration of the rusting solution used in the rusting reaction is 0.5 - 2.5%, the oxidizing gas is a mixture of air and pure oxygen, the rusting temperature is 60 - 90 °C, the liquid-solid ratio is 1.5 - 5:1, and the rusting time is 30 - 60 min.

[0012] Preferably, in step S1, dilute hydrochloric acid is used as a catalyst, which can make the product Fe(OH)3 easier to separate compared with ammonium chloride used in the traditional process.

[0013] Preferably, in step S3, the primary synthetic rutile is washed and dewatered of residual iron oxide red by a dehydration screen, and then the hydrated iron oxide and chloride ions attached to the surface are further washed by a vacuum belt filter. The washing water of the vacuum belt filter can be used for recycling in the washing process after multi-stage precipitation, or can be used as makeup water for the closed cooling process after neutralization.

[0014] Preferably, in step S3, the acid leaching is carried out in a stirring tank to accelerate the reaction by stirring. The concentration of hydrochloric acid used is 8 - 13 wt%, the solid-liquid mass ratio is 1:2 - 5, the temperature is 20 °C - 100 °C, and the time is 30 - 90 min.

[0015] Preferably, in step S3, after acid leaching, the mixed material enters a thickener, and the upper layer liquid is returned to prepare the acid leaching solution; the lower layer ore particles are sent to a belt filter for de-acidification and washing. The de-acidification liquid in front of the belt filter is returned to prepare the acid leaching solution; the washing liquid with a relatively high chloride ion concentration in the middle is returned to the rusting process as the rusting stock solution; the washing water with a low chloride ion concentration at the back can be used for recycling in the washing process after precipitation.

[0016] The beneficial effects of the present invention are as follows:

[0017] The present invention provides a method for preparing synthetic rutile by reducing ilmenite. By using industrial hydrochloric acid instead of the traditional ammonium salt aqueous solution or the mixture of ammonium salt and ferric chloride as the rusting agent: on the one hand, the industrial hydrochloric acid used in the present invention is prepared from hydrochloric acid, the stock solution with a relatively high chloride ion concentration before washing after rusting and pickling, and water. By recycling the stock solution with a relatively high chloride ion concentration before washing after rusting and pickling, the usage amount of hydrochloric acid can be greatly reduced, which not only saves costs but also avoids environmental pollution; on the other hand, dilute hydrochloric acid can be used as a catalyst, which can make the product Fe(OH)3 easier to separate compared with ammonium chloride. The oxidizing gas used for rusting in the present invention is a mixed gas of air and pure oxygen, and according to different rusting raw materials, the mixing ratio of air and pure oxygen can be dynamically adjusted to make the reaction conditions in the optimal state.

[0018] During the entire rusting and acid leaching processes of the present invention, the recycling efficiency of liquid raw materials (rusting agents, acid leaching solutions, washing solutions, etc.) is extremely high. Specifically, after acid washing, the mixed materials enter a thickener, and the upper-layer liquid is returned to prepare the acid leaching solution; the lower-layer ore particles are sent to a belt filter for de-acidification and washing. The de-acidification liquid in front of the belt filter is returned to prepare the acid leaching solution; the washing solution with a relatively high chloride ion concentration in the middle is returned to the rusting process as the original rusting solution; the washing water with a low chloride ion concentration at the back can be used for the washing process after precipitation and recycling. In summary, the process flow is reasonably designed, simple to operate, has a high raw material utilization rate, and no environmental pollution. Description of the Drawings

[0019] Figure 1 It is the process flow chart of the embodiment of the present invention. Detailed Embodiments

[0020] The present invention will be further described below in conjunction with the drawings and embodiments, but the specific embodiments of the present invention are not limited to the following embodiments.

[0021] Embodiment 1

[0022] Using reduced ilmenite with a TiO2 mass content of 52.44% and a metallization rate of 93.13% as the raw material.

[0023] The reduced ilmenite and the rusting solution (2.0 wt% industrial hydrochloric acid) are added into a stirring rusting tank (stirring rate: 360 r / min). At the same time, air is blown in by a suspension fan and mixed with the oxygen sent from the air separation station (mixing ratio: 4:6), so that the reduced ilmenite undergoes an electrochemical rusting reaction under weakly acidic and aerobic conditions (temperature: 80 °C, time: 60 min, solid-liquid ratio 1:5)), turning the metallic iron in the reduced ilmenite into hydrated iron oxide, thereby increasing the titanium dioxide content, that is, obtaining primary artificial rutile. The rusting process is an exothermic reaction without an external heat source. During the rusting process, the rusting solution is appropriately supplemented to ensure that the liquid-solid ratio and temperature are within a reasonable range.

[0024] After the rusting reaction ends, the artificial rutile and the hydrated iron oxide slurry are first separated by a hydrocyclone, and then the hydrated iron oxide slurry is filtered by a filter press. The obtained iron oxide mud is used to manufacture refined iron oxide. The artificial rutile is then washed and dehydrated with a dehydration sieve to remove the residual iron red, and then the hydrated iron oxide and chloride ions attached to the surface are continuously washed through a vacuum belt filter. The washing water of the vacuum belt filter can be used for the washing process after multi-stage precipitation and recycling, or can be used as the supplementary water for the cooling water in the closed cooling process after neutralization.

[0025] Artificial rutile with substandard titanium dioxide grade after rust removal and washing is subjected to acid leaching in hydrochloric acid solution with a concentration of 12 wt% (temperature: 75 °C, time: 90 min, solid-liquid ratio: 1:5) to further remove residual iron oxide, manganese oxide, calcium oxide, magnesium oxide and other oxides in the artificial rutile. The acid leaching is carried out in a stirring tank, and the reaction is accelerated by stirring (stirring rate: 400 r / min). After acid washing, the mixed material enters the thickener, and the upper layer liquid is returned to prepare the acid leaching solution; the lower layer ore particles are sent to a belt filter for deacidification and washing. The deacidification liquid in front of the belt filter is returned to prepare the acid leaching solution; for the intermediate washing liquid with a relatively high chloride ion concentration, it is returned to the rust removal process as the original rust removal liquid; the washing water with a low chloride ion concentration at the back can be used for recycling in the washing process after precipitation.

[0026] The washed artificial rutile enters a drying cylinder for drying (temperature: 120 °C, time: 60 min). The semi-finished product of the dried artificial rutile is inspected, mixed evenly and then packaged and stored in the warehouse, which is the finished product of artificial rutile by the rust removal method.

[0027] After detection, the TiO2 grade of the artificial rutile obtained in Example 1 is 90.33%, CaO: 0.96%, MgO: 0.17%, meeting the requirements of raw materials for chloride process titanium dioxide.

[0028] Example 2

[0029] Using reduced ilmenite with a TiO2 mass content of 51.62% and a metallization rate of 92.16% as the raw material.

[0030] The specific process steps refer to Example 1, the difference is that the mixing ratio of air and oxygen is 2:8, the rust removal reaction (temperature: 70 °C, time: 60 min, solid-liquid ratio 1:5), and acid leaching is carried out with hydrochloric acid solution with a concentration of 10 wt% (temperature: 65 °C, time: 90 min, solid-liquid ratio 1:5), and the other conditions are the same as those in Example 1.

[0030] After detection, the TiO2 grade of the artificial rutile obtained in Example 2 is 92.16%, CaO: 1.07%, MgO: 0.22%, meeting the requirements of raw materials for chloride process titanium dioxide.

[0031] Example 3

[0032] Using reduced ilmenite with a TiO2 mass content of 51.62% and a metallization rate of 91.16% as the raw material.

[0033] The specific process steps refer to Example 1, the difference is that the mixing ratio of air and oxygen is 0:10, the rust removal reaction (temperature: 60 °C, time: 60 min, solid-liquid ratio 1:5), and acid leaching is carried out with hydrochloric acid solution with a concentration of 10 wt% (temperature: 85 °C, time: 90 min, solid-liquid ratio 1:5), and the other conditions are the same as those in Example 1.

[0034] After detection, the TiO₂ grade of the artificial rutile obtained in Example 3 is 93.88%, CaO: 0.87%, MgO: 0.13%, meeting the requirements of raw materials for chloride process titanium dioxide.

[0035] Comparative Example 1:

[0036] Using reduced ilmenite with a TiO₂ mass content of 51.62% and a metallization rate of 91.16% as the raw material.

[0037] The specific process steps refer to Example 1, the difference is that the rust inhibitor is ammonium chloride solution with a concentration of 2.0 wt%, the mixing ratio of air to oxygen is 4:6, the rust reaction (temperature: 80 °C, time: 60 min, solid-liquid ratio 1:5), acid leaching is carried out with hydrochloric acid solution with a concentration of 10 wt% (temperature 85 °C, time 90 min, solid-liquid ratio 1:5), and the other conditions are the same as those in Example 1.

[0038] After detection, the TiO₂ grade of the artificial rutile obtained in Comparative Example 1 is 84.88%, CaO: 1.67%, MgO: 1.71%, not meeting the requirements of raw materials for chloride process titanium dioxide.

[0039] Comparative Example 2:

[0040] Using reduced ilmenite with a TiO₂ mass content of 51.62% and a metallization rate of 91.16% as the raw material.

[0041] The specific process steps refer to Example 1, the difference is that the rust inhibitor is industrial hydrochloric acid with a concentration of 2.0 wt%, the mixing ratio of air to oxygen is 10:0, the rust reaction (temperature: 80 °C, time: 60 min, solid-liquid ratio 1:5), acid leaching is carried out with hydrochloric acid solution with a concentration of 10 wt% (temperature 85 °C, time 90 min, solid-liquid ratio 1:5), and the other conditions are the same as those in Example 1.

[0042] After detection, the TiO₂ grade of the artificial rutile obtained in Comparative Example 2 is 76.19%, CaO: 1.44%, MgO: 2.24%, not meeting the requirements of raw materials for chloride process titanium dioxide.

[0043] The above are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. For those skilled in the art of this technology, the improvements and transformations obtained without departing from the technical concept of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing artificial rutile by reducing ilmenite, characterized in that, The method comprises the following steps: S1. Adding reduced ilmenite into a rusting tank, introducing an oxidizing gas for rusting reaction, and obtaining primary synthetic rutile and hydrated iron oxide slurry after separation by a cyclone, a high-frequency screen, and washing; S2. Filter-pressing the hydrated iron oxide slurry obtained in step S1 by a filter press, and using the obtained iron oxide mud to manufacture refined iron oxide; S3. Subjecting the primary synthetic rutile obtained in step S1 to hydrochloric acid leaching reaction after washing, feeding the mixed material after acid leaching into a thickener, returning the upper-layer liquid to prepare acid leaching solution; sending the lower-layer ore particles to a belt filter for acid removal and washing; S4. Drying the washed synthetic rutile obtained in step S3 by a drying cylinder to obtain finished synthetic rutile.

2. The method for preparing high-quality titanium-rich materials by reducing ilmenite according to claim 1, characterized in that, In step S1, the metallization rate of the reduced ilmenite is between 90% and 95%.

3. The method for preparing high-quality titanium-rich materials by reducing ilmenite according to claim 1, characterized in that, In step S1, the rusting solution is industrial hydrochloric acid of about 0.5-2.5 wt%, which is prepared from hydrochloric acid, the stock solution with a relatively high chloride ion concentration before rusting and pickling and washing, and water.

4. The method for preparing high-quality titanium-rich materials by reducing ilmenite according to claim 1, characterized in that, In step S1, the oxidizing gas is a mixture of air and pure oxygen.

5. The method for preparing high-quality titanium-rich materials by reducing ilmenite according to claim 1, characterized in that, In step S1, the rusting temperature is 60-90 °C, the liquid-solid ratio is 1.5-5:1, the rusting time is 30-60 min, and the stirring rate is 60-600 r / min.

6. The method for preparing high-quality titanium-rich materials by using reduced ilmenite according to claim 1, characterized in that, In step S1, dilute hydrochloric acid not only serves as a rusting agent but also as a catalyst, and can make the product Fe(OH)3 easier to separate compared with ammonium chloride used in the traditional process.

7. The method for preparing high-quality titanium-rich materials by reducing ilmenite according to claim 1, characterized in that, In step S3, the acid leaching reaction is carried out in a stirring tank, the concentration of hydrochloric acid used is 8-13 wt%, the solid-liquid mass ratio is 1:2-5, the temperature is 20 °C-100 °C, the time is 30-90 min, and the stirring rate is 60-600 r / min.

8. The method for preparing high-quality titanium-rich material by reducing ilmenite according to claim 1, characterized in that, In step S3, the mixed material after acid leaching enters a thickener, the upper-layer liquid is returned to prepare acid leaching solution; the lower-layer ore particles are sent to a belt filter for acid removal and washing; the acid removal liquid in front of the belt filter is returned to prepare acid leaching solution; the washing liquid with a relatively high chloride ion concentration in the middle is returned to the rusting process as rusting stock solution; the washing water with a low chloride ion concentration at the back can be used for recycling in the washing process after precipitation.

9. The method for preparing high-quality titanium-rich materials by reducing ilmenite according to claim 1, characterized in that, In step S4, the drying temperature is 80-800 °C, and the drying time is 10-120 min.

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