JP6727918B2 - Sc recovery method - Google Patents

Description

The present invention relates to a Sc recovery method. More specifically, the present invention relates to a method for recovering Sc from a chloride residue after recovering titanium tetrachloride from titanium ore.

Titanium is refined from titanium ore by the Kroll process. In this Kroll method, titanium ore and coke are put into a fluidized bed reactor, and chlorine gas is blown from the lower part of the fluidized bed reactor. As a result, gaseous titanium tetrachloride is produced, which is recovered and reduced with magnesium or the like, and finally titanium sponge is produced.

However, titanium ore contains useful substances other than titanium. Patent Document 1 discloses a method for recovering a useful metal from a titanium ore. Specifically, a method of chlorinating titanium ore and leaching the obtained residue of the crude chlorination furnace with HCl is disclosed.

Further, Patent Document 2 discloses a method for recovering unreacted titanium ore and coke from the chloride residue. Specifically, after washing the chlorinated residue with water, it is separated into solid matter and waste liquid, and because solid matter contains unreacted titanium ore and coke, it is returned to the fluidized bed reactor for reuse. Is disclosed.

JP-A-3-115534 JP-A-2014-181153

As described above, in refining titanium, it is useful if useful substances can be recovered without discarding what was conventionally a waste. Further, when recovering a substance, it is further beneficial if the recovery rate can be improved and/or contamination of other impurities can be reduced.

In view of the above, it is an object of the present invention to provide a method for recovering a useful substance (for example, Sc or the like) after reducing contamination (for example, Fe) with other substances.

As a result of earnest studies in view of the above problems, the present inventor has found that good results can be obtained by performing the flotation step before the step of removing Fe. Based on these findings, the present invention is specified as follows in one aspect.
(Invention 1)
A method of recovering Sc, comprising:
A step of performing flotation treatment on the chloride residue, thereby obtaining tailing, flotation and post-flotation liquor;
Performing HCl leaching on the tailings, thereby obtaining a post-leaching liquor;
Removing Fe from the post-leaching solution;
After the Fe is removed, a step of extracting Sc from the post-leaching liquid is included,
The chloride residue is a solid residue that is produced when reacting titanium ore, coke, and chlorine gas to produce gaseous or liquid titanium tetrachloride,
The method.
(Invention 2)
The method according to invention 1, wherein the flotation treatment is carried out at a pH of 4 or less.
(Invention 3)
The method according to invention 1 or 2, wherein in the flotation treatment, the Fe concentration in the suspension is controlled to 10 g/L or less.
(Invention 4)
The method according to any one of Inventions 1 to 3, wherein the flotation treatment is carried out at pH 2 to 3.8.

The present invention, in one aspect, performs a flotation process on a chloride residue. As a result, each component of the chloride residue is distributed to tailings, floats, and liquid after flotation. At that time, Sc and the like are mainly distributed to tailings, and Fe is mainly distributed to the liquid after flotation. Therefore, Sc can be recovered with high efficiency (and the load of the step of removing Fe, which has been conventionally performed, can be reduced).

The present invention, in one aspect, performs a flotation process in a predetermined pH range. Thereby, the Fe removal rate can be further increased.

In one aspect of the present invention, the Fe concentration in the suspension is controlled to 10 g/L or less. As a result, the Fe removal rate can be further increased.

FIG. 6 is a flow chart of a method in an embodiment of the present invention. 7 shows a result of flotation in an embodiment of the present invention. 4 shows the pH dependence of flotation in one embodiment of the present invention. 5 shows the Fe concentration dependence of flotation in one embodiment of the present invention (coke recovery). It is a flow chart about the crawl method (prior art).

1. Chloride residue
1-1. Purification of Titanium Conventionally, titanium is generally purified from titanium ore by the Kroll method. FIG. 5 shows a part of the flow. Charge titanium ore and coke into a fluidized bed reactor. Then, chlorine gas is blown in from the lower part of the fluidized bed reactor. Titanium ore reacts with chlorine gas to produce titanium tetrachloride. Titanium tetrachloride is in a gaseous state at the temperature inside the reactor. This titanium tetrachloride in the gaseous state is sent to the next cooling system and cooled. The cooled titanium tetrachloride becomes liquid and is recovered.

1-2. When titanium tetrachloride the residue chloride vaporized is sent to the next cooling system aboard the airflow pulverulent impurities it is sent to the cooling system together. The impurities include chlorides other than titanium (iron, vanadium, silicon, etc.), unreacted titanium ore, unreacted coke, and the like. These impurities are recovered in solid form in the cooling system. In the present specification, this recovered product is referred to as a chloride residue.

1-3. Quality of Chloride Residue The chloride residue obtained in the above-mentioned process has various elements, and may include the following elements, for example.
Sc 50ppm-150ppm
10% to 50% of C (coke)
Fe 3% to 5%
Of course, the present invention can be applied to elements other than the above and/or contents other than the above.

2. Flotation (flotation)
By carrying out flotation (flotation) on the chloride residue, desired substances can be recovered and unwanted substances can be eliminated. More specifically, by carrying out flotation, the substances in the chloride residue can be distributed to tailing, flotation, and post-flotation liquid. Then, the desired substance can be recovered from each fraction. Undesired substances can be distributed to other fractions, thus increasing recovery.

2-1. Flotation conditions The following conditions can be adopted as the flotation conditions for the above recovery and removal.
Pulp concentration 200-600 (dry-g/L)
Flotation time 5 to 30 minutes Flotation pH 2 or more (preferably 4 or less, more preferably 3.8 or less)
Collection agent 100 to 300 g/t (preferably 200 to 300 g/t)
Foaming agent 50 to 200 g/t (preferably 100 to 150 g/t)

The scavenger acts to enhance the hydrophobicity of the surface of the target mineral by selectively adsorbing it. The specific substance is not particularly limited, and examples thereof include kerosene. The amount of the scavenger is 100 to 300 g/t (preferably 200 to 300 g/t). If it is less than 100 g/t, floating ore is difficult to obtain, which is not desirable.

A foaming agent is a substance that dissolves in a solvent to stabilize the foam of the solution. Specific examples of the substance include, but are not limited to, methylisobutylcarbinol (MIBC) and pine oil. The amount of the foaming agent is 50 to 200 g/t (preferably 100 to 150 g/t). If it is less than 50 g/t, floating ore is difficult to obtain, which is not desirable.

2-2. Flotation pH (Correlation between pH and Sc recovery)
The pH of the flotation is preferably 4 or less. The reason for this is that if the pH exceeds 4, Fe hydroxide tends to precipitate (that is, distribution to the liquid after flotation does not occur easily). Further, the pH is more preferably 2 to 3.8. The reason for this is that the recovery rate of Sc is improved and the removal rate of Fe is increased.

2-3. Concentration of Fe in flotation solution (Fe concentration and Sc recovery)
Further, Fe in the chloride residue is dissolved in the liquid after flotation. Therefore, the Fe concentration increases during the flotation process. The Fe concentration in the flotation liquid during the flotation step is preferably controlled to 10 g/L or less. This significantly improves the removal of Fe. For example, a removal rate of Fe of 90% or more can be achieved. Further, the Fe concentration in the flotation liquid during the flotation step is more preferably 9 g/L or less. Thereby, the recovery rate of Sc is further improved. Even more preferably, it is 5 g/L or less. Thereby, the Fe removal rate of 95% or more can be achieved. In order to control the Fe concentration below a certain concentration, it is desirable to monitor the Fe concentration in the flotation liquid and periodically replace the flotation liquid.

3. After flotation processing
3-1. After the tailing flotation process, solids not trapped in the foam settle to the bottom. This precipitate is called tailing. Fe and coke are largely removed from the tailings obtained through the flotation process, as compared with the chloride residue. Therefore, it is possible to reduce the load of the Fe removal process performed later. Moreover, the recovery rate of Sc and rare earth can be improved. For tailings, Sc and rare earths can be recovered by the leaching step described later.

3-2. Floating concentrate
After the flotation step, a solid substance trapped in bubbles is obtained. This trapped solid material is called floating concentrate (floating ore). In the float ore obtained through the above flotation step, coke derived from chloride residue is mainly distributed.

3-3. Liquid after Flotation After the flotation step, the specific component derived from the chloride residue is dissolved in the liquid after flotation. For example, Fe in the chloride residue can be dissolved in the liquid after flotation. With respect to the proportion (distribution rate) of Fe distributed from the chloride residue to the liquid after flotation, 90% or more can be achieved. In other words, Fe is hardly distributed to tailings and floats. Fe is a substance to be removed when recovering a useful substance (such as Sc) from the chloride residue. Therefore, the load of the subsequent step of removing Fe can be reduced.

4. Tailing treatment
4-1. HCl leaching Conventionally, HCl leaching treatment was directly performed on the chloride residue to extract the target component in the chloride residue. However, the method of the present invention includes a step of performing a flotation treatment on the chloride residue before performing the HCl leaching treatment. Then, HCl leaching treatment is performed on the tailings after the flotation treatment.

The leaching process can be specifically performed under the following conditions.
Solution component HCl 0.1-8 mol/L
Time 0.5 to 5 hours Temperature Normal temperature to 60°C

4-2. The solution after Fe extraction and leaching contains components such as Sc and Fe. When recovering Sc, it is desirable to remove Fe as an unnecessary component. Therefore, a process of further extracting Fe from the liquid after leaching can be performed. Although the specific method is not particularly limited, for example, when tributyl phosphate (Tri-butyl phosphate, TBP) is used, Fe is extracted on the oil phase side. After that, Fe on the oil phase side is back-extracted. Then, the liquid after the back extraction becomes waste water.

4-3. On the other hand, Sc extraction can be performed on the aqueous phase side. For example, TBP and HCl can be added to extract Sc on the oil phase side. Then, Sc is back-extracted. Then, oxalic acid can be added to the back extract to obtain a Sc precipitate. This can be calcined to obtain oxidized Sc.

A more concrete example of the above-described embodiment will be described.

The quality of chloride residue, tailings, floats, etc. was measured by alkali melting-ICP emission spectroscopy. The constituent amounts of each element in the solution were measured by ICP emission spectroscopy.

5. Example 1 (Sc recovery, Fe removal)
5-1. The residue chloride residue chloride, in a furnace for recovering titanium tetrachloride volatilized in titanium smelting, as a solid, a dust recovered after slow cooling is air. The chloride residue was obtained from Toho Titanium Co., Ltd. Then, before subjecting to the next flotation step, the quality of the chloride residue was measured (FIG. 2).

5-2. Flotation conditions Flotation was performed on the chloride residue whose quality was measured under the following conditions.
Pulp concentration 261 dry-g/L (23%)
Flotation time 15 minutes Flotation pH 3-4
Flotation liquid temperature Normal temperature Collection agent 100 g/t (kerosene)
Foaming agent 200g/t (pine oil)
Amount of air blown 1.3 to 1.7 L/min・L

Constituents were measured for tailings, floats, and post-flotation liquids obtained after flotation. The result is shown in FIG. The chloride residue before the flotation step contained Sc, Fe, C and other rare earths. Then, after the flotation step, most of Sc was distributed to the tailings (distribution rate 81%). Further, most of Fe was distributed to the liquid after the flotation (distribution ratio 96%). Here, by recovering Sc from the tailing, coke and Fe can be greatly reduced.

6. Example 2 (coke recovery, Fe removal and pH dependence)
The flotation step was carried out under the same conditions as in Example 1. However, the pH was changed to 2, 3.5, and 4. Results are shown in FIG. FIG. 3 shows the relationship between the pH of the flotation liquid (horizontal axis) and the Fe removal rate (vertical axis). The Fe removal rate is a value obtained by dividing the Fe content in the liquid after flotation by the Fe content in the chloride residue.

Referring to FIG. 3, the removal rate of Fe was 96.4% at pH 4. Further, when the pH was set to 3.5, the Fe removal rate was 98.3%, which was a higher value. Further, as in the case of pH 3.5, the value was high at pH 2. As described above, it was shown that there is pH dependency in the removal of Fe. In particular, it has been found that particularly good values can be achieved in removing Fe in the range of about pH 3.8 or less.

7. Example 3 (Fe removal and Fe concentration dependency)
The flotation step was carried out under the same conditions as in Example 1. However, the Fe concentration in the flotation liquid was monitored, and when the Fe concentration became constant, the flotation liquid was replaced. Specifically, there are three patterns: replacement when the Fe concentration reaches 5 g/L, replacement when the Fe concentration reaches 10 g/L, and replacement when the Fe concentration reaches 15 g/L. It was carried out in.

The results are shown in Fig. 4. It was shown that the Fe removal rate increased as the Fe concentration of the flotation liquid decreased. In particular, the Fe removal rate was over 90% when the Fe concentration was 10 g/L or less. Further, the Fe removal rate exceeded 95% when the Fe concentration was 5 g/L or less.

Claims (3)

A method of recovering Sc, comprising:
A step of performing flotation treatment on the chloride residue, thereby obtaining tailing, flotation and post-flotation liquor;
Performing HCl leaching on the tailings, thereby obtaining a post-leaching liquor;
Removing Fe from the post-leaching solution;
After the Fe is removed, a step of extracting Sc from the post-leaching liquid is included,
The residue chloride, Ri solid residue der occurring when generating the gaseous or liquid titanium tetrachloride by reacting the titanium ore and coke and chlorine gas,
Floatation processing is performed at pH 4 or less,
The method. The method according to claim 1 , wherein in the flotation treatment, the Fe concentration in the suspension is controlled to 10 g/L or less. The method according to claim 1 or 2 , wherein the flotation treatment is carried out at pH 2 to 3.8.