JP2018168448A - Titanium oxide, and method of recovering coke - Google Patents

Abstract

To recover titanium oxide and/or coke.SOLUTION: A method of recovering titanium oxide and/or coke includes: a process of sieving a chloride residue by-produced in a production process of titanium tetrachloride into coarse particles and fine particles; a process of recovering the coarse particles; and a process of feeding the coarse particles into a reaction furnace for producing titanium tetrachloride, where in the process of sieving, the residue is sieved into the coarse particles and the fine particles by a reference number of 12-60 μm.SELECTED DRAWING: None

Description

  The present invention relates to a method for recovering titanium oxide and coke. More specifically, the present invention relates to a method for recovering titanium oxide and coke from a product generated in a titanium smelting process.

  Titanium is refined from titanium ore by the crawl method. In this crawl method, titanium ore and coke are introduced into a fluidized bed reactor, and chlorine gas is injected from the lower part of the fluidized bed reactor. As a result, gaseous titanium tetrachloride is generated, recovered and reduced with magnesium or the like, and finally sponge titanium is generated.

  However, the titanium ore contains useful substances other than titanium oxide. Patent Document 1 discloses a method for recovering useful metals from titanium ore. Specifically, a method of chlorinating titanium ore and leaching HCl of the resulting crude chlorination furnace residue is disclosed. Patent Document 2 discloses a technique for recovering as a valuable material by increasing the coke concentration in a by-product containing impurity metal chloride by-produced in the production process of titanium tetrachloride using titanium ore as a raw material. Patent Documents 3 and 4 disclose a technique for recovering titanium dioxide by a cyclone treatment.

Japanese Patent Application Laid-Open No. 3-115534 JP-A-2006-050166 European Patent No. 0318231 US Pat. No. 6,399033

  In the crawl method, gaseous titanium tetrachloride is produced in a fluidized chlorination furnace. And this titanium tetrachloride is collect | recovered in a place different from a fluid chlorination furnace. At this time, a large amount of chloride residue is generated. It costs money to process this as industrial waste. On the other hand, this chloride residue contains industrially useful substances such as titanium oxide and coke. If these substances can be recovered more efficiently, it will be advantageous in terms of cost. Then, an object of this invention is to provide the method of collect | recovering useful substances from a chloride residue efficiently.

  When recovering titanium oxide and coke from the chloride residue, filtration may be performed for the purpose of removing moisture. As a result of intensive studies by the present inventors, it has been found that the filtration process can be remarkably made efficient by classifying the chloride residue and removing or reducing a specific particle size range.

Based on the above findings, the present invention is specified as follows in one aspect.
(Invention 1)
A method for recovering titanium oxide and / or coke,
The method
A step of classifying the chloride residue by-produced in the production process of titanium tetrachloride into coarse and fine particles;
Recovering the coarse particles;
Adding the coarse particles to a reactor for producing titanium tetrachloride,
The step of classifying includes classifying into coarse particles and fine particles using 12 to 60 μm as a reference value.
The method.
(Invention 2)
2. The method according to invention 1, wherein the reference value is 20 to 53 [mu] m.
(Invention 3)
3. The method according to invention 1 or 2, wherein the classifying step includes classification by a liquid cyclone or a wet sieve.
(Invention 4)
4. The method according to any one of claims 1 to 3, wherein the classifying step includes classifying with a hydrocyclone.
(Invention 5)
The method according to any one of Inventions 1 to 4, wherein the classifying step includes filtering the coarse particles.

  In the present invention, in one aspect, the chloride residue is classified in advance with a specific reference value. And the particle group which has a particle size distribution of a specific range can be applied to a filtration process. Thereby, the time concerning a filtration process can be shortened significantly.

  In the present invention, in one aspect, classification is performed by a liquid cyclone. Thereby, separation based on specific gravity becomes possible, and the amount of contamination other than the target product can be reduced.

1. Chloride residue
1-1. Purification of titanium Titanium tetrachloride is generally purified from titanium ore by the crawl method. To explain a part of the refining flow, first, titanium ore and coke are charged into a fluidized bed reactor. And chlorine gas is blown in from the lower part of a fluidized bed reactor. Titanium ore reacts with chlorine gas to produce titanium tetrachloride. Titanium tetrachloride is in a gaseous state at the temperature in the reactor. This gaseous titanium tetrachloride is sent to the next cooling system to be cooled. The cooled titanium tetrachloride becomes liquid and is recovered.

1-2. When titanium tetrachloride chloride residue gas state is sent to the next cooling system aboard the airflow pulverulent impurities it is sent to the cooling system together. The impurities include titanium oxide and unreacted coke. These impurities are recovered in solid form in the cooling system. In this specification, this recovered substance is called a chloride residue. The chloride residue may be slurried or in the form of dry particles. Typically, valuable metals can be recovered using slurried materials.

1-3. Quality of Chlorinated Residue Chlorinated residue obtained in the above-described process includes titanium oxide and coke. If these can be recovered, the disposal cost can be suppressed, and at the same time, the profit can be improved by using the recovered material. Although the present invention is not limited by the following theory, the chlorination residue is finely divided titanium oxide and coke produced during the production of titanium tetrachloride, so that most of its constituents are titanium ore and coke. Derived from.

1-4. Pretreatment of Chlorinated Residue The aforementioned chloride residue is in a high temperature state immediately after being recovered during titanium smelting, and needs to be cooled before performing a process for recovering valuable metals. The cooling method is not particularly limited, and may be cooled by means such as air cooling or water cooling.

Moreover, it is preferable to wash a chloride residue with water before performing the classification described later. This is because water-soluble impurities such as FeCl ₂ can be removed by washing with water. Moreover, if it is water washing, the cooling process mentioned above can also be performed simultaneously.

2. Classification method After rinsing with water, the chlorinated residue can be classified into coarse and fine particles. The classification method is not particularly limited, and may be dry or wet. More preferred is wet. This is because when the chloride residue is washed with water, it does not require the trouble of drying. Further, as a classification method, a sieve having a specific size may be used. As the wet classification, a hydraulic classifier, a horizontal water classifier, a hydrocyclone, or a centrifugal settling machine may be used. As a dry classification, an air separator or an air classifier may be used.

The reference value for classification may be adopted as an upper limit value and a lower limit value in consideration of a size range in which a large amount of target recovered material (for example, coke or titanium oxide) is contained. For example, any two numerical value combinations selected from 60 μm, 53 μm, 45 μm, 38 μm, 30 μm, 25 μm, 22 μm, 20 μm, and 12 μm can be adopted as the upper limit value and the lower limit value. For example, the reference value may be 12 μm or more and 60 μm or less, 38 μm or more and 60 μm or less, or 12 μm or more and 20 μm or less. If it is 60 μm or less, there is a possibility that the loss of titanium oxide, coke and the like to be collected becomes small. In addition, the amount of Si contamination may be reduced. Therefore, the ratio of the Ti amount to the Si amount (that is, Ti / Si) may increase. On the other hand, when the thickness is 12 μm or more, there is a possibility that the time required for the subsequent filtration can be shortened. Moreover, there is a possibility of preventing the entry of fine Si. Therefore, the ratio of the Ti amount to the Si amount (that is, Ti / Si) may increase. If it is 20 μm or more, there is a possibility that the realization is easy with some classification means (for example, classification with a sieve). On the other hand, if it is 20 μm or more, the quality of the recovered titanium may increase. Conversely, if it is 20 μm or less, there is a possibility that the quality of the recovered coke may increase.
After classification, the coarse grain side containing more coke and titanium oxide can be recovered.

2-1. When a sieve is used as the sieve classification means, the mesh size can be appropriately determined based on the classification reference value. For example, when classification is performed using 25 μm as a reference value, an opening of 25 μm (500 mesh for JIS standard) can be used. And the thing which passed the sieve can be made into a fine grain, and the thing remaining on the sieve can be considered as a coarse grain, and can be collect | recovered.

2-2. When a liquid cyclone is used as the liquid cyclone classification means, the operating conditions of the device can be set based on the classification reference value. The hydrocyclone can be operated in a continuous mode rather than a batch type like the above sieve. Therefore, it is possible to shorten the time required for the series of steps, which is advantageous. Further, the liquid cyclone can be classified by specific gravity, unlike the classification by the sieve. This is very useful for separation of compounds having different specific gravities (for example, TiO ₂ (about 3.9 to 4.3 g / cm ³ ) and SiO ₂ (about 2.2 g / cm ³ )).

  In one example, when a liquid cyclone is used, first, the chloride residue is first classified under various conditions, and the particle size distribution on the coarse particle side and the fine particle side is examined. Then, the condition for the partial classification efficiency to be 50% is found. For example, when classification is performed using 25 μm as a reference value (classification point), classification can be performed under the condition that the particle size at which partial classification efficiency is 50% is 25 μm.

2-3. Effects of Classification The following description is not intended to limit the scope of the present invention. By eliminating the particle size in a specific range, it is considered that the total amount of chloride residue to be processed is reduced, and a series of processing steps can be made efficient. Further, it is considered that clogging of the filter during the filtration process can be avoided by eliminating the particle size in a specific range. Furthermore, it is considered that the amount of water to be removed in the filtration step can be reduced by eliminating the particle size in a specific range.

3. Processing after classification
3-1. After the filtration treatment classification, coarse particles can be collected and the coarse particles can be subjected to the next treatment. For example, filtration can be performed for the purpose of separating and removing moisture contained in the coarse particles. Examples of filtration include, but are not limited to, pressure filtration, suction filtration, heavy pressure filtration, centrifugal filtration, and the like. Prior to filtration, the efficiency of the filtration process can be significantly improved by classifying in advance and removing fine particles.

3-2. Granulation and drying After removing moisture by the above method, the particles may be dried to further remove moisture. Further, the particles can be further granulated to a specific size (for example, a particle size range of 0.2 mm to 5 mm). Thereby, after re-introducing into the fluidized bed reactor, it is possible to reduce the possibility of being recovered as a chloride residue again by riding in the air stream without being reacted. As a means for granulating, a solid can be mixed with a binder. Examples of the binder include an organic binder (eg, PVA), an inorganic binder (eg, sodium silicate), and the like. Granulation may be performed after the particles are dried, or may be performed immediately after the filtration treatment (that is, before the particles are dried).

Example 1 Measurement of Particle Size Distribution of Chlorinated Residue Chlorinated residue is a substance recovered as a solid in a furnace for recovering titanium tetrachloride volatilized in titanium smelting. The chloride residue was obtained from Toho Titanium Co., Ltd. The chloride residue was in a slurry state that had been washed with water.

Classification was performed on the chloride residue. Specifically, it was carried out as follows according to the procedure of “JIS Z 8815-1994 General Screening Test Method”.
(1) Stack the sieves with large openings so that they are on the top.
(2) Put the sample on the uppermost sieve and cover it.
(3) The sieving device (AS200 manufactured by Retsch) is operated with “Amplitude: 1.00”.
(4) Sprinkle water in the shower and sieve until the liquid coming out from the bottom becomes transparent.
(5) Remove the sieve from the apparatus.
(6) Collect the sample, filter and weigh.
The results are shown in Table 1 below. As a result of classification, it was shown that the particle group that passed through the sieve having an opening of 25 μm accounted for about 18% of the total in the chloride residue. In addition, it was shown that the particle group that passed through a sieve having a mesh opening of 38 μm accounted for about 22% of the whole, and the particle group that passed through a sieve having a mesh opening of 53 μm accounted for about 33% of the whole. The distribution rate “+150” in Table 1 represents a particle group remaining on a sieve having an opening of 150 μm. “−25” represents a particle group that has passed through a sieve having an opening of 25 μm. Further, “150/106” represents a particle group that passes through a sieve having an opening of 150 μm and remains on the sieve having an opening of 106 μm.

Example 2 (component analysis of chloride residue before classification)
Component analysis of the chloride residue before classification was performed. Alkaline melting-ICP emission spectroscopy was used (ICP-AES, manufactured by Seiko Instruments Inc., SPS7700). The results are shown in Table 2.

Example 3 (component analysis of chloride residue after classification)
Next, each classified particle group was weighed. The elemental analysis of each particle group was performed using alkali melting-ICP emission spectroscopic analysis as described above (ICP-AES, manufactured by Seiko Instruments Inc., SPS7700). The results are shown in Table 3. When Table 2 and Table 3 were compared, the following was shown. That is, in the particle groups remaining on the sieves having openings of 53 μm, 38 μm, and 25 μm, the ratios of C and Ti were increased as compared to before classification. On the other hand, the amount of Si and the like decreased. Further, referring to Table 1, the total amount of the residue after classification could be reduced by at least 17.3% (when the opening was 25 μm).

  Thus, by classifying, it was shown that the total amount can be reduced while maintaining or improving the ratio of Ti and C.

Example 4 (classification by liquid cyclone)
Component analysis was performed using a chlorination residue of a lot different from the chlorination residue used in Example 1. The analysis method is the same as in Example 1. The results are shown in Table 4.

Next, classification using a liquid cyclone was performed using this chloride residue under the following conditions.
Device name: KS-15 (manufactured by industry)
Pump name: MD-40RZ (Iwaki)
Actual flow rate: 11.2L / min
Pressure: 0.14 MPa
Slurry concentration: 0.8wt%
Slurry amount: 100 L (classification point 14 μm), 50 L (classification point 21 μm)

  In the case of a test with a classification point of 14 μm, the chloride residue slurry was supplied from the cushion tank to the hydrocyclone using a pump. And it classified into the coarse grain and the fine grain, and collect | recovered the coarse grain and the fine grain, respectively.

  In the case of a test with a classification point of 21 μm, after classifying into coarse particles and fine particles by the same method, the coarse particles were returned again to the cushion tank. Then, coarse particles were sent again to the hydrocyclone. In this way, the coarse particle side was repeatedly circulated (so as to be distributed more on the fine particle side), and the operation was terminated when the amount of slurry in the cushion tank reached 1.5L. And the slurry which remained in the cushion tank was collect | recovered as a coarse grain.

  The component analysis on the coarse grain side after classification was performed in the same manner as in Example 3. The results are shown in Table 5 below.

  As a result, after classification (both classification point 21 μm and classification point 14 μm), the ratio of Ti was maintained or improved. Further, the relative amount of Ti and Si (Ti / Si) was improved. Further, when the classification point was 21 μm and the classification point was 14 μm, it was shown that the Ti content was significantly increased in the classification point of 21 μm compared to before classification. Further, when the relative amounts of Ti and Si were compared, the mixing of Si could be further reduced. Furthermore, when the classification point is 21 μm and the classification point is 14 μm, the quality of C is significantly increased when the classification point is 14 μm.

Example 5 (Filtration of chloride residue after classification)
Each of the slurry of the chloride residue before classification and the slurry of the chloride residue classified to the coarse particle side by the classification in Example 4 (classification point 14 μm) were filtered under the following conditions.
Apparatus: Magnetic funnel 237/7 (manufactured by ASONE Corporation)
Suction filtration bottle 1000ml (manufactured by ASONE Corporation)
Filter paper: Quantitative filter paper No. manufactured by Advantech. 3 φ125
Slurry weight of chloride residue before classification: 0.55 kg
Slurry concentration of chloride residue before classification: 20 g / L
Slurry weight of chlorination residue after classification (coarse side): 0.32 kg
Slurry concentration of chloride residue after classification (coarse side): 172 g / L

  As a result, the chloride residue slurry before classification had a filtration rate of 36 ml / min. On the other hand, the slurry of the chloride residue after classification was 58 ml / min. Therefore, it was shown that the time of the filtration process can be significantly shortened by classification.

Claims (5)

A method for recovering titanium oxide and / or coke,
The method
A step of classifying the chloride residue by-produced in the production process of titanium tetrachloride into coarse and fine particles;
Recovering the coarse particles;
Adding the coarse particles to a reactor for producing titanium tetrachloride,
The step of classifying includes classifying into coarse particles and fine particles using 12 to 60 μm as a reference value.
The method.   The method according to claim 1, wherein the reference value is 20 to 53 μm.   3. The method according to claim 1 or 2, wherein the classifying step includes classification by a liquid cyclone or a wet sieve.   The method according to any one of claims 1 to 3, wherein the classifying step includes classification with a hydrocyclone.   The method according to any one of claims 1 to 4, wherein the classifying step includes filtering the coarse particles.