JPS61209916A - Preparation of synthetic rutile - Google Patents

Abstract

PURPOSE:To utilize supplied sulfuric acid completely and to recover ferrous sulfate completely in the prepn. of synthetic rutile by the leaching method using sulfuric acid by adding sulfuric acid to the leaching liquid and cooling the liquid. CONSTITUTION:Titanium one after oxidation and reduction is leached with leaching liquid contg. H2SO4. Obtd. Ti-contg. material having high quality is separated and dried, and then calcined to obtain synthetic rutile. In this process, the temp. of leaching liquid contg. solid components is adjusted to ca.30-80 deg.C where the solubility for ferrous sulfate is high, thus, ferrous sulfate (monohydrate) deposited in the leaching liquid is dissolved. Then, the solid matter in the leached liquid having adjusted temp. is separated and removed (including fine particle separation). Then, H2SO4 corresponding to the equivalent amt. of the reaction for leaching is added to the leaching liquid and cooled, thus, ferrous sulfate in the leaching liquid is separated by crystallization. Separated crystals of ferrous sulfate are washed with industrial water, and residual liquid of the crystallization is mixed with the washing water or industrial water and utilized again for leaching.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing synthetic rutile and an improvement in the method for producing synthetic rutile by a sieving and sulfuric acid leaching method.

(Prior art and its problems) Titanium ores such as ilmenite, allicinite, and riccoxin are used as raw materials for producing synthetic rutile, but ilmenite ore is mainly used industrially. This ilmenite ore is as shown in Table 1 below.
Its main components are titanium and iron.

Table 1 Synthetic rutile is generally produced by removing iron from the ilmenite ore, and one method for producing it is sulfuric acid leaching.

This sulfuric acid leaching method oxidizes and reduces ilmenite ore to thermally reform the iron content into a form that is easily dissolved in acid, and then leaches impurities such as iron and manganese with sulfuric acid to produce high-grade T.
ie, a method of obtaining synthetic rutile by obtaining a contained material and firing it.

Regarding such a sulfuric acid leaching method, for example, Japanese Patent Application Laid-Open No. 49-3
This method has been proposed in Japanese Patent Application Laid-open No. 7484, Japanese Patent Application Laid-open No. 7519/1983, and so on. However, these proposals concern leaching conditions and leaching methods, and there is no originality in the treatment of the leachate generated as a result of leaching, and the leachate is simply treated as waste liquid. In other words, the waste liquid was neutralized with ammonia to produce ammonium sulfate, or the waste liquid was neutralized with lime to produce gypsum.

The amount of sulfuric acid used during sulfuric acid leaching is usually
This amount is about 1.5 to 3 times the theoretical amount required to dissolve the iron in the ore. Therefore, a considerable amount of sulfuric acid remains in the leachate after leaching, but this leachate has conventionally been treated as waste acid, which is very uneconomical.

Moreover, 100 to 300 f/ of ferrous sulfate produced by leaching is dissolved in the leachate, and if these ferrous sulfates are purified, they will have industrial utility value as raw materials for ferrite production. expensive. However, in the past, only iron oxide with low added value was produced as a by-product during neutralization, so this was not rational either.

(Means for Solving the Problems) The present invention attempts to solve the above problems, and its purpose is to completely utilize the supplied sulfuric acid in the production of synthetic rutile by the sulfuric acid leaching method. The object of the present invention is to provide an economical method for producing synthetic rutile that allows complete recovery of ferrous sulfate.

In order to achieve the above object, the present inventors investigated the leachate generated in the sulfuric acid leaching method. Figure 3 shows a test using thermally modified ilmenite ore.
f/L 1FeS0.0~300 f/1. TiO! of the titanium-containing material obtained as a result of leaching at 150°C for 8 hours using a leaching agent of TiO! This indicates the content.

As is clear from Fig. 3, even if ferrous sulfate is present in the leaching agent at an amount of θ ~ 300 r/, the leaching of iron from the ore is not inhibited, and it is the same as the conventional sulfuric acid leaching method. A highly concentrated titanium-containing material was obtained under these conditions. This means that although 100 to 150 tons of ferrous sulfate remains in the liquid obtained by cooling and crystallizing the leachate generated in the sulfuric acid leaching method, there will be no problem even if sulfuric acid is newly added to this liquid and the leachate is used again. It means there is no.

The present invention was created based on the above knowledge,
The feature is that by adding sulfuric acid to the leachate generated in the sulfuric acid leaching method, that is, the leachate from which the leached ore and the generated fine powder have been separated, and cooling it, the ferrous sulfate in the leachate is crystallized and separated. The objective is to reuse the crystallization residue as a leachate.

(Example) Embodiments of the present invention will be described below based on the accompanying drawings.

The 70-chart in FIG. 1 shows an overview of the present invention.
In the figure, the flow from titanium ore to synthetic rutile is the same as in the conventional sulfuric acid leaching method. That is, after oxidation and reduction treatment with titanium ore, it is leached with a leachate containing sulfuric acid, the obtained high-grade titanium-containing material is separated and dried, and it is burned to obtain synthetic rutile.

The feature of the present invention is that the leachate generated in the leaching process is not treated as waste liquid, but that the leachate is subjected to rational treatment and recycled for use. In other words, oxidation
Titanium ore that has been thermally modified through reduction treatment is leached with a leachate whose main components are sulfuric acid and ferrous sulfate.

To explain in detail, sulfuric acid leaching is normally carried out under pressure conditions of 120 to 180°C, but under such conditions, the solubility of ferrous sulfate is significantly reduced. part precipitates. This, Tie and fine powder produced by hydrolysis of dissolved titanium during leaching form aggregates,
It becomes suspended in the leachate. Therefore, the present invention aims to convert the leachate containing solids into
The temperature is adjusted to ~80°C, optimally 40~70°C, and the ferrous sulfate (monohydrate) precipitated in the leachate is dissolved. At this time, in order to completely dissolve the entire amount of ferrous sulfate, during leaching, it is desirable to bring the leaching agent into contact with the titanium ore so that the liquid composition after leaching is approximately less than Fe504400f/.

Next, the solid content in the temperature-adjusted leachate is separated and removed (including fine particle separation). The fine powder TlO2 is made into synthetic rutile by firing through processes such as drying and pressurized bottom molding. After performing separation and removal as described above, sulfuric acid in an amount equivalent to the reaction in leaching is added to the leachate and cooled to crystallize and separate ferrous sulfate in the leachate.

The separated ferrous sulfate crystals are washed with industrial water, and the remaining crystallization liquid is mixed with this washing water or aqua regia and used again as a leaching agent.

FIG. 2 shows the dissolved concentration of ferrous sulfate in a sulfuric acid solution at various temperatures, and the crystallization of ferrous sulfate utilizes the difference in the dissolved concentration of ferrous sulfate.

In the present invention, crystallization can be carried out not only by cooling the crystallization stock solution, but also by increasing the sulfuric acid preparation. It is a more reduced version.

Specific examples of the present invention will be shown below.

Based on the flowchart 1c shown in FIG. 1, synthetic rutile was continuously produced one jar per hour using Western Australian ilmenite ore whose composition is shown in Table 1 as a raw material.

1818 tons of ilmenite ore per hour in an oxidation furnace
Air oxidation was performed at 0°C for 1 hour, and then CO reduction was performed at 700°C for 3 hours in a reduction furnace. The obtained thermally modified ore was fed into a leaching tank and leached at 150° C. with a residence time of 81 hours. At this time, the leaching agent supply rate was 11 tons per hour, and the leaching agent composition was
1. So.

200t/L%FeSO4100t/l.

Next, the leachate containing solid components (ore, ferrous sulfate crystals, fine powder Tie, etc.) was supplied from the leaching tank to a 60° C. temperature adjustment tank, and the precipitated ferrous sulfate was dissolved during a residence time of 1 hour. Next, the leachate and ore were separated, and the leachate ore was washed with water, air-dried, and treated in a kiln at 900°C for 30 minutes to form a tie.

IKf of synthetic rutile at a concentration of 96 cm was obtained per hour.

On the other hand, the leachate is obtained by separating the fine powder T t Ox with a centrifuge to obtain I-I, 80.110 f/l, Fe3O423
8f! 11 t% of liquid with a composition of /l was added per hour. 9ssHtso4 was added at 5 liters per hour to 0.56 t to make the amount equal to the theoretical amount required to dissolve the iron in the ore.
℃ was fed into the crystallizer.

Next, the precipitated ferrous sulfate crystals were extracted from the crystallization tank, and centrifuged while washing with aqua regia to obtain 27,509 ferrous sulfate (heptahydrate) crystals per hour. The composition of the crystallization residue is H, 80,
222y/l, F″eSO4111f/l at 9.00pm/hour.
I got a 9.

Next, 9.9 t/hour of the crystallization residual liquid and lt of the previous washing water were mixed, H, So, 200 f/l, FeSO4100
11 liquids with a composition of t/l were obtained per hour. The leachate was circulated by continuously supplying this as a leachant to the leach tank.

(Effects of the Invention) According to the present invention as described above, in the method for producing synthetic rutile by the sulfuric acid leaching method, sulfuric acid is added to the leachate from which the leached ore and the generated fine powder have been separated, and ferrous sulfate is extracted by cooling. Since the sulfuric acid is separated by crystallization, the entire amount of sulfuric acid is effectively used and is not discharged outside the system.
However, the entire amount of ferrous sulfate produced by leaching crystals can be recovered. Therefore, according to the present invention, it is possible to produce synthetic rutile which is extremely economical and environmentally friendly.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing an overview of the method for producing synthetic rutile according to the present invention, FIG. 2 is a graph showing the dissolved concentration of Fe 804, and FIG. 3 is a graph showing the dissolved concentration of Fe50. 3 is a graph showing the relationship between concentration and TiOt content. Patent applicant: Nippon Steel & Tube Co., Ltd. Inventor: Hideyuki Yoshikoshi
2nd factor Temperature (0C) 3rd factor FeSO4 concentration (9/9L)

Claims (1)

[Claims] Method for producing synthetic rutile using sulfuric acid leaching method leached ore and generated fines Add sulfuric acid to the leachate from which the grain powder has been separated and cool it. Ferrous sulfate is crystallized and separated by A method for producing synthetic rutile characterized by the following.