JPH0629135B2 - Purification method of titanium sulfate solution - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for purifying a titanium sulfate solution.

<Prior Art and Problems> Titanium sulfate is important as a raw material for titanium oxide pigments.

Titanium oxide pigment has the highest refractive index among white pigments,
Moreover, since the particles are fine and uniform, they have maximum coloring power and hiding power, and are also excellent in weather resistance, heat resistance, and stability against acids, alkalis and the like. In combination with its high dispersibility, it is widely used as an additive for various paints, printing inks, paper-making materials, various synthetic resins and electronic materials.

Generally, as a method for producing titanium oxide, there are a sulfuric acid method in which a titanium component is treated by treating a titanium-containing ore with sulfuric acid, and a chlorine method in which a titanium component is treated by treating with chlorine. The present invention relates to the purification of titanium sulfate liquid obtained by the sulfuric acid method.

In the sulfuric acid method, titanium-containing ores such as ilmenite (FeO · Fe ₂ O ₃ · TiO ₂ ) are dissolved in sulfuric acid, cooled to remove iron as iron sulfate by precipitation, and titanium sulfate contained in the liquid is hydrolyzed. Titanium oxide is produced by separating and firing the titanium hydroxide obtained as described above.

By the way, the above-mentioned raw ore mainly contains manganese, niobium, lead, chromium, vanadium, zinc, aluminum, calcium, iron, etc. in addition to titanium, and when they remain as impurities in titanium oxide, pigment characteristics, electrical properties It adversely affects the characteristics. In particular, niobium reduces whiteness and impairs electrical characteristics. Therefore, when the titanium-containing ore is dissolved in sulfuric acid, it is necessary to remove the impurities from the titanium sulfate liquid.

Conventionally, a solvent extraction method has been known as a method for removing niobium among the above impurities. (Ind.Eng.Chem.Prod.Res.Dev
elop., Vol 10, No. 4 1971) However, in the solvent extraction method, a trace amount of niobium (0.05 to 0.2 g Nb /) must be extracted from a solution containing a large excess of titanium (50 to 100 g Ti /). However, it is necessary to use a large amount of hydrochloric acid and hydrofluoric acid together in order to increase the selectivity, and the handling is complicated. Larger amounts of extraction solvent are required, which makes it difficult to carry out on an industrial scale.

<Means for Solving Problems> The present inventor can efficiently separate not only niobium but also impurities other than niobium by treating the titanium sulfate solution with activated carbon, and requires a large apparatus configuration necessary for solvent extraction. It has been found that it can be easily removed without using.

According to the present invention, there is provided a method for purifying a titanium sulfate solution, which comprises contacting a titanium sulfate solution obtained by dissolving a titanium-containing ore with sulfuric acid with activated carbon to remove impurities in the solution. Further, as a preferred embodiment thereof, the above-mentioned purification method for separating manganese, niobium, lead, chromium, vanadium, zinc, aluminum, calcium, iron as the impurities from the titanium sulfate solution is provided.

The step of dissolving the titanium-containing ore with sulfuric acid may be carried out by an ordinary method, and the dissolving conditions and the like are not particularly limited. Usually, after crushing titanium-containing ore, the concentration is 100-1800g /
Dissolve with sulfuric acid. Titanium-containing ore (ilmenite)
When is heated with a concentrated sulfuric acid solution, titanium sulfate and iron sulfate are produced by the following reaction.

_{FeTiO 3 + 2H 2 SO 4 =} FeSO 4 + TiOSO 4 + 2H to ₂ O above solution was added to _{H 2} O or thin _H 2 SO ₄ to adjust the concentration, 50~200Tig / titanium sulphate solution is obtained.
The titanium sulfate solution contains manganese, niobium, lead, chromium, vanadium, zinc, aluminum, calcium, iron and the like as the impurities to the extent shown in Table 1, depending on the place of production of the titanium-containing ore. There is.

Therefore, Fe scrap is added to the titanium sulfate solution, Fe ³⁺ in the solution is reduced to Fe ²⁺ and cooled, and FeSO ₄ is crystallized,
Remove from liquid.

Then, the titanium sulfate solution is brought into contact with activated carbon to adsorb the remaining impurities on the activated carbon and then separated.

The treatment with the above activated carbon may be performed before crystallizing FeSO ₄ . Since the content of Fe is much higher than that of other impurities, it is preferable to carry out the activated carbon treatment after crystallization of FeSO ₄ because the burden on the activated carbon can be reduced.

To contact the titanium sulfate with the activated carbon, the activated carbon used is packed into a column in a layered manner, and the titanium sulfate solution is passed through the layered portion, or the activated carbon and the titanium sulfate solution are mixed and stirred in the treatment tank. Any method such as a method of bringing them into contact with each other or a method of using these methods together may be used.

As the activated carbon to be used, commercially available one can be used, and the shape thereof may be any of granular, powdery, fibrous, sheet-like, honeycomb-like and the like.

The temperature of the titanium sulfate solution to be treated with activated carbon may be room temperature to 60 ° C. In addition, the removal rate of impurities is slightly better when the liquid temperature is room temperature.

Titanium sulfate liquid from which impurities have been removed by activated carbon treatment is
It can be directly sent to the hydrolysis step. In the hydrolysis step, titanium sulfate causes precipitation of titanium hydroxide as shown in the following formula, and if the precipitation is separated and baked, titanium oxide TiO ₂ free of impurities can be obtained.

TiOSO ₄ + 2H ₂ O = TiO (OH) ₂ + H ₂ SO ₄ On the other hand, activated carbon that has adsorbed impurities is treated with hydrochloric acid, hydrofluoric acid, caustic soda, etc. to regenerate the activated carbon, and impurities are recovered from the treatment liquid as necessary. You can Alternatively, the used activated carbon may be dried as it is and then burnt by heating to recover impurities as oxides.

<Effects of the Invention> According to the purification method of the present invention, impurities such as manganese, lead, chromium, vanadium, zinc, aluminum, calcium, and iron in addition to niobium can be separated from the titanium sulfate solution with good selectivity. It is possible to manufacture highly pure titanium oxide.

Further, the present invention is excellent in practicability such that the treatment operation is extremely simple because the activated carbon is contacted with the titanium sulfate solution, and the existing titanium oxide production process can be carried out without being significantly changed.

Further, niobium and the like can be recovered in a high yield by regenerating the activated carbon and recovering impurities, and the recovered niobium can be used as various production raw materials and the like, so that it can be a stable niobium supply source.

<Example> Example 1 A polyethylene column having a diameter of 30 mm was packed with activated carbon (Kuraray Chemical Co., Ltd .; Kuraray Coal GLC), and a titanium sulfate liquid having a composition of the following table and a liquid temperature of 60 ° C was supplied at a rate of 0.1 to 2 / H
The liquid was supplied at r (SV ratio 0.5 to 10).

After passing through the column, the content of impurities in the titanium sulfate solution discharged from the column was analyzed. The results are shown in Table 3.

As is clear from the above results, impurities of manganese, niobium, lead, chromium, vanadium, zinc, aluminum, calcium and iron are separated at a high removal rate over a very wide range of SV ratios. On the other hand, the concentrations of Ti and free sulfuric acid are almost unchanged, so it is understood that the above impurities are separated from Ti and free sulfuric acid with good selectivity.

Example 2 Activated carbon treatment was carried out in the same manner as in Example 1 except that the SV ratio was fixed at 2 and the type of activated carbon was changed, and the effect of removing impurities from the titanium sulfate solution was examined for each type of activated carbon. The results are shown in Table 4. As is clear from the above results, the treatment method of the present invention can achieve a high effect of removing impurities even if the type of activated carbon is changed.

Example 3 The SV ratio was fixed at 2, and the temperature of the titanium sulfate solution was 20, 40, 60.
Activated carbon treatment was carried out in the same manner as in Example 1 except that the temperature was set to 0 ° C., and the effect of removing impurities from the titanium sulfate solution was examined at each solution temperature. The results are shown in Table 5. As is clear from the above results, the treatment method of the present invention achieves a high impurity removing effect at any of the above temperatures, and has the highest removing effect at room temperature.

Example 4 500 ml of titanium sulfate solution was placed in a beaker, and 12.5 g and 25 g of activated carbon (Kuraray Coal GLC) were added to this solution,
The titanium sulfate solution was brought into contact with the activated carbon for 1 to 3 hours while stirring. The results are shown in Tables 6 and 7. In this embodiment, the amount of activated carbon is reduced as compared with the column system, but the impurities are separated with good selectivity.

Claims (2)

[Claims] 1. A method for purifying a titanium sulfate solution, which comprises dissolving a titanium-containing ore in sulfuric acid to bring a titanium sulfate solution into contact with activated carbon to remove impurities in the solution. 2. Manganese, niobium, lead, as the impurities,
A method for separating chromium, vanadium, zinc, aluminum, calcium and iron from a titanium sulfate solution.
Item purification method.