A method for producing reduced titanium

Abstract

The present invention discloses a method for producing reduced titanium, comprising the following steps: S1. Batching: Mix coarse pulverized coal and ilmenite evenly according to a mass ratio of 2.5 - 3.5:10, add them to the tail of the rotary kiln, and at the same time spray fine pulverized coal into the kiln at the head of the rotary kiln; S2. Reaction: Supply a certain amount of air into the kiln, control the temperature at the head of the kiln to be 1150 - 1180 °C, and the temperature at the tail of the kiln to be 550 - 650 °C, so that the ilmenite undergoes a reduction reaction to obtain reduced titanium. By effectively controlling various production factors, the present application can obtain reduced titanium with a high metallization rate and low FeO without adding a reduction aid, avoid kiln blocking, and improve the operation rate of the rotary kiln; at the same time, it can effectively control the CaO and C contents in the product. The reduced titanium obtained by the method provided by the present application has a metallization rate of over 85%, a CaO content of ≤ 0.15%, and a C content of ≤ 0.3%.

Description

Technical Field

[0001] The present invention belongs to the field of metallurgical technology, and particularly relates to a method for producing reduced titanium. Background Art

[0002] As a raw material for synthetic rutile used in chlorination, it is generally required that TiO2%>58%, FeO<8%, CaO<0.15%, and C<0.4% in the reduced titanium. At present, the production of reduced titanium is mainly carried out by means of a rotary kiln. However, the existing production methods have certain deficiencies. For example, Patent CN109097576 discloses a method for producing reduced titanium for welding electrodes from titanium iron sand ore. In the production, an additional auxiliary agent sodium bicarbonate needs to be added. Sodium bicarbonate is a compound with a low softening temperature and is likely to cause the rotary kiln to clog, affecting the normal production of the rotary kiln. Moreover, it does not mention how to control the CaO and C contents in the product.

[0003] In the field of reduced titanium production, there are already many means and studies on how to improve reduced titanium and stabilize its metallization rate. However, there are no clear means for controlling the CaO and carbon contents in reduced titanium. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for producing reduced titanium to solve the deficiencies of the existing technology. By producing through the method provided by the present invention, no reduction auxiliary agent needs to be added, and high-quality reduced titanium with a high metallization rate, low CaO, and low C contents can be obtained, which can be used as a high-quality raw material for fluidized bed titanium chloride subsequently.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] A method for producing reduced titanium, comprising the following steps:

[0007] S1. Batching: Mix pulverized coal and ilmenite evenly according to a mass ratio of 2.5-3.5:10, add them to the tail of the rotary kiln, and at the same time spray pulverized coal fines into the kiln at the head of the rotary kiln by using compressed air. The addition amount of the pulverized coal fines is in a mass ratio of 0.8-1.5:10 to the ilmenite; the particle size of the pulverized coal is 5-25 mm, and the particle size of the pulverized coal fines is 1-15 mm;

[0008] S2. Reaction: Supplement a certain amount of air into the kiln so that the air volume is in a ratio of 800-1200:1 m 3 / t to the ilmenite, control the temperature at the head of the kiln to be 1150-1180 °C, and the temperature at the tail of the kiln to be 550-650 °C, so that the ilmenite undergoes a reduction reaction to obtain reduced titanium.

[0009] Preferably, the mass ratio of the particles with a particle size of 5-25 mm in the pulverized coal in step S1 is>95%, and the mass percentage content of the volatile matter is controlled to be 33-36%.

[0010] Preferably, in the fine pulverized coal described in step S1, the mass ratios of particle sizes of 1-3 mm, 3-8 mm, and 8-15 mm are 20-40%, 20-40%, and 20-40% respectively, and the mass percentage content of volatile matter is not less than 33%.

[0011] Preferably, the mass percentage content of ash in the coarse pulverized coal and the fine pulverized coal is <7%, and in the ash, Fe2O3 < 8% and CaO < 10% by mass percentage.

[0012] Preferably, the mass percentage content of TiO2 in the ilmenite is ≥48%, and the mass percentage content of CaO is <0.1%.

[0013] Preferably, the reaction time described in step S2 is more than 9 h.

[0014] Preferably, after step S2, the following steps S3 and S4 are further included:

[0015] S3. Cooling: Cooling the material after the reaction is completed through a cooling kiln to a temperature below 60°C;

[0016] S4. Separation: Screening and magnetic separation of the cooled material to separate the pulverized coal and obtain reduced titanium.

[0017] Preferably, the particle size of the reduced titanium described in step S4 is controlled to be < +20 mesh, and the large particles of reduced titanium exceeding this particle size are crushed and subjected to re-screening and magnetic separation treatment.

[0018] Preferably, the magnetic separation intensity is above 1500 Gs, and five-stage magnetic separation is used for magnetic separation.

[0019] The reduced titanium production method provided by this application can obtain reduced titanium with a high metallization rate and low FeO without adding a reduction aid by effectively controlling various production factors, avoiding kiln blocking, and improving the operation rate of the rotary kiln; at the same time, it can effectively control the CaO and C contents in the product. The reduced titanium obtained by the method provided by this application has a metallization rate of more than 85%, a CaO content ≤ 0.15%, and a C content ≤ 0.3%. Description of the Drawings

[0020] Figure 1 is the five-stage magnetic separation flow chart provided by this application. Detailed Embodiments

[0021] The present invention provides a reduced titanium production method, including the following steps:

[0022] S1. Ingredients: Mix the coarse coal powder and ilmenite evenly according to the mass ratio of 2.5 - 3.5:10, and add them to the tail of the rotary kiln. At the same time, use compressed air at the head of the rotary kiln to spray fine coal powder into the kiln. The mass ratio of the added amount of fine coal powder to ilmenite is 0.8 - 1.5:10; the particle size of the coarse coal powder is 5 - 25 mm, and the particle size of the fine coal powder is 1 - 15 mm;

[0023] S2. Reaction: Supply a certain amount of air into the kiln. The air volume to ilmenite ratio is 800 - 1200:1 m 3 / t. Control the temperature at the head of the kiln to be 1150 - 1180 °C and the temperature at the tail of the kiln to be 550 - 650 °C, so that the ilmenite undergoes a reduction reaction to obtain reduced titanium.

[0024] In this application, coarse coal powder and fine coal powder are respectively fed at the tail and head of the kiln. Among them, the coarse coal powder at the tail of the kiln is the main raw material for the reduction reaction in the kiln. It requires a relatively coarser particle size to ensure that CO can be provided throughout the process from the tail of the kiln to the head of the kiln, guarantee the reduction of materials, and at the same time burn in the kiln as the main fuel to maintain the kiln temperature, so it requires a higher calorific value; a large amount of the coarse coal powder fed at the tail of the kiln will be consumed when it reaches the head of the kiln. To ensure sufficient reducing atmosphere at the head of the kiln, this application supplements some fine coal particles at the head of the kiln. At the same time, to maintain the stability of the kiln temperature, coal is sprayed at the head of the kiln as supplementary fuel.

[0025] To ensure that the metallization rate of the finished product is controlled above 85%, a better reducing atmosphere (higher CO concentration) is required in the rotary kiln. To maintain a high concentration of CO while the coal fully releases heat, strict control of the air volume is required, that is, it can ensure the combustion of coal without excessive oxidation combustion resulting in a low CO concentration. Therefore, it is preferably that the air volume supplied into the kiln to ilmenite ratio is 800 - 1200:1 m 3 / t.

[0026] The reduction reaction in the rotary kiln (reaction temperature above 900 °C) occurs below the material layer. The increase in reaction temperature mainly refers to the increase in material temperature. The higher the temperature at the kiln tail, the earlier the material temperature can reach the reaction temperature, and the earlier the reduction reaction can start. However, the higher the temperature, the higher the coal consumption in the overall production process, which will cause more coal ash to accumulate in the system and affect the control of trace elements. The material temperature at the kiln head has reached the reaction temperature. Appropriate increase in temperature is the key to improving the metallization rate. At the same time, since the coal at the kiln head has burned out, too high a reaction temperature will cause over-oxidation combustion of CO, resulting in local high temperature in the rotary kiln, causing serious ring formation problems and affecting the normal operation of the overall rotary kiln. Therefore, through optimization, the present application limits the temperature at the kiln tail to 550 - 650 °C respectively, which can not only ensure that the temperature at the kiln tail is in a relatively high range and start the reduction reaction as early as possible, but also prevent the temperature from being too high so as to affect the control of trace elements. The temperature at the kiln head is limited to 1150 - 1180 °C, making the temperature at the kiln head appropriate, which can not only improve the metallization rate, but also prevent local high temperature and over-oxidation combustion from affecting the normal operation of the rotary kiln.

[0027] By limiting the temperature at the kiln head, the present application can effectively reduce sintering and lower the C content in the reduced titanium product. Moreover, in addition to ilmenite and pulverized coal, the present application does not use any other additives such as sodium bicarbonate and Ca-containing sulfur-fixing agents, etc., which can not only reduce the adverse effects of additives on normal production, but also reduce the introduction of Ca and ensure the effective control of the Ca element and C element contents in the reduced titanium product.

[0028] Therefore, the reduced titanium production method provided by the present application can obtain reduced titanium with high metallization rate and low FeO without adding reduction additives by effectively controlling various production factors, avoiding kiln blocking and improving the operation rate of the rotary kiln; at the same time, it can effectively control the CaO and C contents in the product. The reduced titanium obtained by the method provided by the present application has a metallization rate of more than 85%, a CaO content ≤ 0.15%, and a C content ≤ 0.3%.

[0029] Furthermore, the mass proportion of particles with a particle size of 5 - 25 mm in the coarse pulverized coal > 95%; the mass proportions of particles with particle sizes of 1 - 3 mm, 3 - 8 mm, and 8 - 15 mm in the fine pulverized coal are 20 - 40%, 20 - 40%, and 20 - 40% respectively. Using fine pulverized coal with a three-stage particle size distribution can make the distribution of fine coal in the rotary kiln more uniform.

[0030] Volatile matter is one of the main sources of heat in the kiln. Therefore, in order to ensure the temperature in the kiln, it is necessary to ensure that there is enough volatile matter content. At the same time, fixed carbon is the main component for generating the reducing agent CO. In order to ensure the fixed carbon content and maintain a low coal consumption, the content of volatile matter cannot be too high. Preferably, the mass percentage content of volatile matter in the coarse pulverized coal is controlled at 33 - 36%, and the mass percentage content of volatile matter in the fine pulverized coal is not less than 33%.

[0031] In order to reduce the influence of impurity elements brought in by raw materials on the reduced titanium product, further, the mass percentage content of ash in the coarse pulverized coal and fine pulverized coal is <7%, and Fe2O3 in the ash is <8%, CaO is <10%, calculated by mass percentage; the mass percentage content of TiO2 in ilmenite is ≥48%, and the mass percentage content of CaO is <0.1%.

[0032] Further, the reaction time of step S2 is more than 9 h.

[0033] Further, after step S2, the following steps S3 and S4 are also included:

[0034] S3. Cooling: Cooling the material at the kiln head after the reaction is completed through a cooling kiln to a temperature below 60°C; Cooling can prevent damage to the equipment due to high temperature during the transfer process of the material;

[0035] S4. Sorting: Screening and magnetic separation of the cooled material to separate the pulverized coal and obtain reduced titanium. Through magnetic separation, the unreacted pulverized coal without magnetism and the carbon powder in the reduced titanium can be separated, reducing the C content in the reduced titanium product.

[0036] Preferably, the particle size of the reduced titanium in step S4 is controlled to be <+20 mesh, and the large-particle reduced titanium exceeding this particle size is crushed and re-screened.

[0037] Preferably, the magnetic separation intensity is above 1500 Gs, and five-stage magnetic separation is adopted for magnetic separation. As Figure 1 shown, the specific process is as follows: The material from the cooling kiln enters the rotary screen and is divided into large-particle and small-particle materials. Among them, the small-particle material is sorted by magnetic separators 1-4 and divided into finished reduced titanium and magnetic separation ash. The large-particle material is sorted by magnetic separator 5 and divided into returned coal and coarse material. Among them, the coarse material is crushed and then returned to the rotary screen for screening and magnetic separation, and the returned coal returns to the rotary kiln system.

[0038] Example 1

[0039] S1. Batching: Mix the coarse pulverized coal and ilmenite evenly according to a mass ratio of 3:10, add them to the tail of the rotary kiln, and at the same time spray fine pulverized coal into the kiln at the kiln head of the rotary kiln using compressed air. The addition amount of the fine pulverized coal is in a mass ratio of 1.2:10 to the ilmenite; The proportion of 5-25 mm in the particle size of the coarse pulverized coal is 97%, and the proportions of 1-3 mm, 3-8 mm, and 8-15 mm in the particle size of the fine pulverized coal are approximately 33.3% respectively.

[0040] S2. Reaction: Supply a certain amount of air into the kiln so that the air volume to ilmenite ratio is 1000:1 m 3 / t, control the temperature at the kiln head to be 1170°C and the temperature at the kiln tail to be 600°C, so that the ilmenite undergoes a reduction reaction, and the reaction time is 9 h.

[0041] S3. Cooling: The material after the reaction is cooled in a cooling kiln to a temperature below 60°C.

[0042] S4. Separation: The cooled material is screened and subjected to five-stage magnetic separation with the magnetic induction intensity between 1500 Gs and 3000 Gs to separate the pulverized coal and obtain reduced titanium. The particle size of the reduced titanium is controlled to be less than +20 mesh.

[0043] The component analysis of the ilmenite used in this example is shown in Table 1, the component analysis of the coarse pulverized coal and fine pulverized coal is shown in Table 2, and the metallization rate of the obtained reduced titanium product is 89.43%, and the component analysis is shown in Table 3.

[0044] Table 1

[0045] Element MgO <![CDATA[Al2O3]]> <![CDATA[SiO2]]> <![CDATA[P2O5]]> <![CDATA[SO3]]> CaO <![CDATA[TiO2]]> MnO <![CDATA[Fe2O3]]> Content % 0.26 0.60 1.03 0.05 0.13 0.03 54.30 1.15 40.99

[0046] Table 2

[0047]

[0048] Table 3

[0049] Element MFe TFe FeO Conversion rate C S CaO MgO Content % 31.39 35.10 4.77 89.43 0.2160 0.02790 0.14 0.71

[0050] Example 2

[0051] S1. Batching: The coarse pulverized coal and ilmenite are mixed evenly according to the mass ratio of 2.5:10 and added to the tail of the rotary kiln. At the same time, fine pulverized coal is sprayed into the kiln from the head of the rotary kiln by compressed air. The addition amount of the fine pulverized coal and the mass ratio of the ilmenite is 1.5:10; the proportion of the particle size of the coarse pulverized coal with 5 - 25 mm is 96%, and the proportions of the particle sizes of the fine pulverized coal with 1 - 3 mm, 3 - 8 mm, and 8 - 15 mm are 33.3% respectively.

[0052] S2. Reaction: A certain amount of air is supplemented into the kiln to make the air volume and the ilmenite ratio 1100:1 m 3 / t, control the temperature at the head of the kiln to be 1150°C, and the temperature at the tail of the kiln reaches 550°C to make the ilmenite undergo a reduction reaction, and the reaction time is 9 h.

[0053] S3. Cooling: The material after the reaction is cooled in a cooling kiln to a temperature below 60°C.

[0054] S4. Separation: The cooled material is screened and subjected to five-stage magnetic separation to separate the pulverized coal and obtain reduced titanium. The particle size of the reduced titanium is controlled to be less than +20 mesh.

[0055] The components of the ilmenite, coarse pulverized coal, and fine pulverized coal used in this example are the same as those in Example 1, and the metallization rate of the obtained reduced titanium product is 85.20%, and the specific test results are shown in Table 4.

[0056] Table 4

[0057]

[0058] Example 3

[0059] S1. Batching: Mix the coarse coal powder and ilmenite evenly according to a mass ratio of 3.5:10, and add them to the tail of the rotary kiln. At the same time, use compressed air at the head of the rotary kiln to spray fine coal powder into the kiln. The addition amount of the fine coal powder is in a mass ratio of 0.8:10 to the ilmenite; 98% of the coarse coal powder has a particle size of 5 - 25 mm, and the particle sizes of the fine coal powder of 1 - 3 mm, 3 - 8 mm, and 8 - 15 mm account for 33.3% respectively.

[0060] S2. Reaction: Supply a certain amount of air into the kiln so that the air volume to ilmenite ratio is 800:1 m 3 / t, control the maximum temperature at the head of the kiln to be 1180 °C and the temperature at the tail of the kiln to be 580 °C, and make the ilmenite undergo a reduction reaction. The reaction time is 9 h.

[0061] S3. Cooling: Cool the material after the reaction through a cooling kiln to a temperature below 60 °C.

[0062] S4. Separation: Screen and perform five-stage magnetic separation on the cooled material to separate the coal powder and obtain reduced titanium, controlling the particle size to be less than +20 mesh.

[0063] The ilmenite, coarse coal powder, and fine coal powder used in this example have the same composition as in Example 1. The metallization rate of the obtained reduced titanium product is 88.15%, and the specific test results are shown in Table 5.

[0064] Table 5

[0065]

[0066] Comparative Example 1

[0067] S1. Batching: Mix the coarse coal powder and ilmenite evenly according to a mass ratio of 2.2:10, and add them to the tail of the rotary kiln. At the same time, use compressed air at the head of the rotary kiln to spray fine coal powder into the kiln. The addition amount of the fine coal powder is in a mass ratio of 1.2:10 to the ilmenite; 97% of the coarse coal powder has a particle size of 5 - 25 mm, and the particle sizes of the fine coal powder of 1 - 3 mm, 3 - 8 mm, and 8 - 15 mm account for 33.3% respectively.

[0068] S2. Reaction: Supply a certain amount of air into the kiln so that the air volume to ilmenite ratio is 1000:1 m 3 / t, control the temperature at the head of the kiln to be 1170 °C and the temperature at the tail of the kiln to be up to 510 °C at most, and make the ilmenite undergo a reduction reaction. The reaction time is 9 h.

[0069] S3. Cooling: The material after the reaction is cooled in a cooling kiln to a temperature below 60°C.

[0070] S4. Sorting: The cooled material is screened and subjected to five-stage magnetic separation to separate the pulverized coal, obtaining reduced titanium with a controlled particle size of less than +20 mesh.

[0071] The ilmenite, coarse pulverized coal, and fine pulverized coal used in this comparative example have the same composition as in Example 1, and the metallization rate of the obtained reduced titanium product is 76.02%. The specific test results are shown in Table 6.

[0072] Table 6

[0073]

[0074] Although the preferred embodiments of the present invention have been described, once those skilled in the art learn the basic creative concept, additional changes and modifications can be made to these embodiments. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention. Obviously, those skilled in the art can make various changes and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for producing reduced titanium, characterized in that, It includes the following steps: S1. Batching: Mix the coarse pulverized coal and ilmenite evenly according to a mass ratio of 2.5 - 3.5:10, and add them to the tail of the rotary kiln. At the same time, spray fine pulverized coal into the kiln from the head of the rotary kiln using compressed air. The mass ratio of the added amount of the fine pulverized coal to the mass of the ilmenite is 0.8 - 1.5:10; the particle size of the coarse pulverized coal is 5 - 25 mm, and the particle size of the fine pulverized coal is 1 - 15 mm; the mass percentages of particles with particle sizes of 1 - 3 mm, 3 - 8 mm, and 8 - 15 mm in the fine pulverized coal are 20 - 40%, 20 - 40%, and 20 - 40% respectively; S2. Reaction: Supply a certain amount of air into the kiln so that the ratio of the air volume to the ilmenite is 800 - 1200:1 m 3 / t, control the temperature at the kiln head to be 1150 - 1180 °C and the temperature at the kiln tail to be 550 - 650 °C, cause the ilmenite to undergo a reduction reaction, the reaction time is 9 h or more, obtain reduced titanium, the metallization rate of the reduced titanium is 85% or more, the CaO content is ≤ 0.15%, and the C content is ≤ 0.3%.

2. The method for producing reduced titanium according to claim 1, characterized in that, In the coarse pulverized coal in step S1, the mass percentage of particles with a particle size of 5 - 25 mm > 95%, and the mass percentage of volatile matter is controlled to be 33 - 36%.

3. The method for producing reduced titanium according to claim 1, characterized in that, The mass percentage of volatile matter in the fine pulverized coal in step S1 is not less than 33%.

4. The method for producing reduced titanium according to claim 1, characterized in that, The mass percentage of ash in the coarse pulverized coal and the fine pulverized coal < 7%, and in the ash, Fe2O3 < 8% and CaO < 10% by mass percentage.

5. The method for producing reduced titanium according to claim 1, characterized in that, The mass percentage of TiO2 in the ilmenite ≥ 48%, and the mass percentage of CaO < 0.1%.

6. The method for producing reduced titanium according to claim 1, characterized in that, After step S2, the following S3 and S4 steps are also included: S3. Cooling: Cool the material after the reaction is completed through a cooling kiln to a temperature below 60°C; S4. Separation: Screen and magnetically separate the cooled material to separate the pulverized coal and obtain reduced titanium.

7. The method for producing reduced titanium according to claim 6, characterized in that, The particle size of the reduced titanium in step S4 is controlled to be < +20 mesh. The large particles of reduced titanium exceeding this particle size are crushed and subjected to re-screening and magnetic separation treatment.

8. The method for producing reduced titanium according to claim 6, characterized in that, The magnetic separation intensity is above 1500 Gs, and five-stage magnetic separation is used for magnetic separation.

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