JP2023102909A - Method for producing titanium concentrate - Google Patents

Abstract

To provide a method for producing a high quality titanium concentrate efficiently by a simple method from a titanium-containing material which includes impurities such as iron and silica components.SOLUTION: A method comprises the steps of: adding a hydrochloric acid-containing leachate (volume V (L)) having initial hydrochloric acid concentration of 15 mass% or more and a titanium-containing material (mass W (kg)) to a reactor so that V/W becomes 3.0 (L/kg) or less, heating the hydrochloric acid-containing leachate to 80°C or higher to leach impurities from the titanium-containing material, and then washing a solid recovered by subjecting slurry after performing the leaching step to solid-liquid separation, followed by drying. Hydrochloric acid recovered by subjecting the slurry to solid-liquid separation is reused as the hydrochloric acid-containing leachate.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a method of removing impurities such as iron from a titanium-containing material such as titaniferous iron ore to produce a high-grade titanium concentrate.

Titanium concentrate is used as a raw material for its chlorination to produce titanium tetrachloride. Titanium tetrachloride is used for the production of titanium dioxide pigments by the chlorine method, the production of metallic titanium, and the like. As such a titanium concentrate, in order to efficiently perform chlorination, a titanium concentrate obtained by removing iron from titanium-containing iron ore such as natural rutile or ilmenite or ilmenite/hematite ore to increase the titanium grade is used. It is known that these titanium concentrates can be produced, for example, by reducing iron (III) contained in titaniferous iron ore or the like to a state of iron (II), leaching with sulfuric acid in the presence of titanium salt hydrolysis promoting seeds and titanium (III) salts, and then calcining (Patent Documents 1 and 2). In the case of these methods, due to the difference in the degree of metamorphism of the raw material, such as titaniferous iron ore (the degree of metamorphism determined by the pressure and temperature to which the ore was subjected before being mined), the titanium grade of the obtained titanium concentrate varies.

Therefore, various methods have been proposed for producing high-grade titanium concentrates using titanium-containing iron ores or the like with a low degree of metamorphism. For example, Patent Document 3 describes a method for producing a titanium concentrate, which comprises preliminarily leaching a pulverized product obtained by pulverizing a titaniferous ore or its analogue to a particle size that can pass through a 330-mesh sieve with an initial hydrochloric acid concentration of 1 to 20% by mass at a reaction temperature of 80°C or lower, and then performing main leaching at a reaction temperature of 90°C or higher with an initial hydrochloric acid concentration of 15 to 20% by mass in the presence of a soluble reducing substance. It is described that the remaining silica component can then be removed.

Japanese Patent Publication No. 49-18330 Japanese Patent Publication No. 49-37484 International Publication WO2021/002332

In order to produce a high-grade titanium concentrate by leaching a titaniferous ore or the like with a low degree of metamorphism with a mineral acid, oxidation, reduction treatment, two-step leaching treatment, etc. are required, and the process is long and complicated. In addition, due to the use of a large amount of mineral acid, there are problems such as (1) equipment and piping made of materials resistant to corrosion are required, and (2) large-scale waste acid treatment equipment is required.

In order to solve the above problems, the present inventors have devised diligently, and as a result, have found that a high-grade titanium concentrate can be obtained without using a large amount of mineral acid by adding a hydrochloric acid-containing leaching solution having an initial hydrochloric acid concentration of 15% by mass or more and a titanium-containing material in a specific ratio to a reaction vessel, and performing a leaching reaction at 80° C. or higher, thereby completing the present invention. In addition, the present invention was completed based on the knowledge that the recovered hydrochloric acid recovered by solid-liquid separation of the slurry after the leaching reaction with hydrochloric acid can be reused as a hydrochloric acid-containing leachate, and that the hydrochloric acid recovered by repeating the same recovery operation multiple times (recovered hydrochloric acid) can be recycled and reused as a hydrochloric acid-containing leachate, so that it is possible to efficiently produce a high-quality titanium concentrate without a facility for processing a large amount of hydrochloric acid.

That is, the present invention is as follows.
[1] A method for producing a titanium concentrate, comprising a leaching step of adding a hydrochloric acid-containing leachate (volume V (L)) having an initial hydrochloric acid concentration of 15% by mass or more and a titanium-containing material (mass W (kg)) to a reaction vessel such that V/W is 3.0 (L/kg) or less, and heating the hydrochloric acid-containing leachate to 80°C or higher to leach impurities from the titanium-containing material.
[2] The method for producing a titanium concentrate according to [1], wherein the hydrochloric acid-containing leachate is hydrochloric acid or recovered hydrochloric acid.
[3] The method for producing a titanium concentrate according to [2], wherein the recovered hydrochloric acid is recovered by solid-liquid separation of the slurry after the leaching step with hydrochloric acid.
[4] The method for producing a titanium concentrate according to [2], wherein the recovered hydrochloric acid is obtained by repeating the operation of solid-liquid separation and recovering the slurry after performing the leaching step with the recovered hydrochloric acid multiple times.
[5] The method for producing a titanium concentrate according to any one of [1] to [4], wherein the hydrochloric acid-containing leachate has an initial hydrochloric acid concentration of 15 to 25% by mass.
[6] The method for producing a titanium concentrate according to any one of [1] to [5], including a step of solid-liquid separation of the slurry after the leaching step, and washing and drying the collected solid matter.
[7] The method for producing a titanium concentrate according to [6], further comprising a step of classifying or granulating after the washing/drying step.
[8] The method for producing a titanium concentrate according to any one of [1] to [7], including a step of calcining the solid after the washing/drying step.
[9] The production method according to any one of [1] to [8], wherein the leaching step is performed at a reaction temperature not higher than the boiling point of the hydrochloric acid-containing leaching solution.
[10] The method for producing a titanium concentrate according to any one of [1] to [9], wherein the titanium-containing material has a TiO ₂ grade of 70 to 90% by mass.
[11] The method for producing a titanium concentrate according to [10], wherein the titanium-containing material has a TiO ₂ grade of 80 to 90% by mass.
[12] The method for producing a titanium concentrate according to any one of [1] to [11], wherein the obtained titanium concentrate has a TiO ₂ grade of 93% by mass or more.
[13] The method for producing a titanium concentrate according to [12], wherein the obtained titanium concentrate has a TiO ₂ grade of 95% by mass or more.

In the method for producing a titanium concentrate of the present invention, impurities can be removed from a titanium-containing material even by using a small amount of a hydrochloric acid-containing leaching solution, and a high-grade titanium concentrate can be produced. Therefore, since a large amount of hydrochloric acid is not used, it can be performed with a small-scale apparatus, piping, etc., and can be sufficiently protected against corrosion. In addition, since the used leaching solution containing hydrochloric acid can be recovered and reused, and can also be recycled and reused, a large-scale waste acid treatment facility is not required.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to these, and various modifications are possible within the described range, and embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Titanium-containing materials applicable to the production method of the present invention include, for example, titanium-containing iron ores such as ilmenite and ilmenite-hematite ores, and titanium slag, which is a by-product of iron smelting. In addition, it is preferable to use a low-grade titanium concentrate such as low-grade synthetic rutile or natural rutile (natural ore) from which impurities such as iron are removed, or similar materials, because a titanium concentrate with a high rutile content can be obtained. The TiO ₂ quality of these titanium-containing materials can be 90% by mass or less, preferably in the range of 70 to 90% by mass, more preferably in the range of 80 to 90% by mass. The TiO ₂ grade of said low-grade titanium concentrate is usually 70-90% by weight, preferably 80-90% by weight.

The titanium-containing material may be appropriately pulverized before use. The pulverization may be dry pulverization or wet pulverization in which pulverization is carried out in a solvent, and can be carried out using commonly used pulverization means such as ball mills, tube mills, vibrating ball mills, sand mills, disc mills, media mills, medialess mills, roller mills, and the like. When wet pulverization is performed, the solvent and the pulverized product are separated into solid and liquid after pulverization. Solid-liquid separation can be carried out by decantation, sedimentation, centrifugation, filtration, membrane separation, etc., preferably by decantation.

In the production method of the present invention, a hydrochloric acid-containing leachate (volume V (L)) having an initial hydrochloric acid concentration of 15% by mass or more and a titanium-containing material (mass W (kg)) are added to a reaction vessel so that V/W is 3.0 (L/kg) or less, and the hydrochloric acid-containing leachate is heated to 80° C. or higher to leach and remove impurities such as iron from the titanium-containing material (leaching step). It is important that the hydrochloric acid-containing leaching solution has an initial hydrochloric acid concentration of 15% by mass or more, so that iron and the like can be removed more efficiently from the titanium-containing material. The initial concentration of hydrochloric acid here means the concentration of hydrochloric acid at the start of leaching. The initial concentration of hydrochloric acid is preferably 15 to 25% by mass from the viewpoint of corrosiveness of the apparatus. Hydrochloric acid-containing leachate includes, for example, hydrochloric acid or recovered hydrochloric acid. Examples of the recovered hydrochloric acid include recovered hydrochloric acid (primary recovered hydrochloric acid) obtained by solid-liquid separation of the slurry after the leaching step with hydrochloric acid, and multiple recovered hydrochloric acid obtained by repeating the same solid-liquid separation and recovery operation multiple times after performing the leaching reaction with the primary recovered hydrochloric acid. When using recovered hydrochloric acid as the hydrochloric acid-containing leaching solution, it may be recovered by repeating the leaching reaction and solid-liquid separation multiple times as long as the initial concentration of hydrochloric acid is 15% by mass or more. If the initial concentration of hydrochloric acid is 15% by mass or less, high-concentration hydrochloric acid or recovered hydrochloric acid may be added. The vessel for the leaching reaction may be an open vessel or a closed vessel such as an autoclave, and a reaction vessel made of a material that is not corroded by hydrochloric acid is used.

It is important that the amount (volume V (L)) of the hydrochloric acid-containing leaching solution used in the leaching step is 3.0 (L/kg) or less in V/W with respect to the mass (mass W (kg)) of the titanium-containing material, preferably 0.5 to 2.5 (L/kg). If the V/W is low, it becomes physically difficult to stir and mix the hydrochloric acid-containing leach solution and the titanium-containing material. It is important that predetermined amounts of the hydrochloric acid-containing leachate and the titanium-containing material are added to the reaction vessel and heated to raise the hydrochloric acid-containing leachate to 80° C. or higher. On the other hand, the reaction temperature is preferably below the boiling point of the hydrochloric acid-containing leachate. If hydrochloric acid vapor is significantly generated at the boiling point of the hydrochloric acid-containing leachate or at a temperature close to the boiling point, the liquid may be cooled appropriately. The reaction time can be appropriately set, and is preferably 2 to 20 hours. When using an open container, the leaching reaction is preferably carried out at 80 to 110° C. (below the boiling point of the hydrochloric acid-containing leaching solution) for 5 to 20 hours. When using a closed container, the temperature and time can be appropriately set according to the pressurization conditions, and the leaching reaction is preferably carried out at 110 to 160° C. for 2 to 18 hours.

In the production method of the present invention, the slurry after the leaching step is subjected to solid-liquid separation by decantation, sedimentation, centrifugation, filtration, membrane separation, or the like into a solid containing titanium concentrate and a leaching solution containing impurities such as iron removed by leaching. Solid-liquid separation may be of a batch type or a continuous type.

The solid matter containing the titanium concentrate obtained by the solid-liquid separation is preferably washed to remove coexisting ions remaining in the solid matter. In the desalting treatment, washing is preferably carried out until the electric conductivity becomes 0.1 S/m or less. After washing the solids, the wet cake is usually dried as necessary to obtain a powder (washing/drying step). As a dryer used for drying, a continuous dryer such as a band dryer and a rotary dryer, a batch dryer such as a box-type shelf dryer, and the like can be appropriately used. Classification or granulation may be performed at the same time as drying. When drying and granulation are performed at the same time, an ordinary granulation dryer can be used, and a fluid bed granulation dryer, a spray dryer, etc. can be appropriately selected. For granulation drying with a spray dryer, it is preferable to make the wet cake after the desalting treatment into a slurry. The titanium concentrate can be granulated to a particle size of 30 to 300 μm by granulation drying. The drying temperature can be set appropriately. The TiO ₂ quality of the titanium concentrate produced as described above is extremely high at 93% by mass or more, and can be 95% by mass or more.

Further, after the washing/drying process, classification or granulation may be performed as necessary (granulation process). Classifiers and granulators can be appropriately adjusted in particle size using ordinary equipment, and in order to chlorinate the titanium concentrate while fluidizing it, for example, it can be sized to a particle size of 30 to 300 μm.

Further, after the washing/drying process, the solid may be calcined as necessary (calcining process). The firing temperature is preferably 300 to 1600°C, more preferably 800 to 1400°C. The calcination can increase the rutile content, hardness and bulk density of the titanium concentrate. When the content of rutile-type titanium oxide is high, the chlorination reaction proceeds easily, and titanium tetrachloride can be produced efficiently. The baking time can be set appropriately.

In the production method of the present invention, when a low-grade titanium concentrate such as low-grade synthetic rutile or natural rutile is used as a raw material, drying without baking at a high temperature can produce a high-grade titanium concentrate containing only titanium oxide having a rutile structure. Titanium oxide having a rutile structure has a good reactivity with chlorine gas, and therefore has the advantage of efficient chlorination reaction.

EXAMPLES Next, the present invention will be specifically described based on Examples and Comparative Examples, but the present invention is not limited by the following Examples and Comparative Examples. The titanium-containing material used and each component of the titanium concentrate produced were analyzed with a wavelength dispersive fluorescent X-ray spectrometer ZSX Primus IV manufactured by Rigaku Corporation.

Table 1 shows the composition of the low-grade titanium concentrate (synthetic rutile) used in the examples as the titanium-containing material. The contents of Ti, Fe, Mn, and Mg are values converted to respective oxides.

Example 1
The above titanium-containing material and 20% by mass hydrochloric acid were placed in a reaction vessel equipped with a stirrer so that V/W = 1 (L/kg), heated while being stirred and mixed, and leached at 108°C (boiling point of the hydrochloric acid-containing leachate) for 5 hours. After completion of the reaction, the solid matter obtained by solid-liquid separation was filtered, washed with water, and dried at 120° C. using a hot air circulation dryer to obtain a titanium concentrate.

Example 2
A titanium concentrate was obtained in the same manner as in Example 1, except that the titanium-containing material and the hydrochloric acid-containing leachate were stirred and mixed so that V/W=2 (L/kg).

Example 3
A titanium concentrate was obtained in the same manner as in Example 2, except that the 20% by mass hydrochloric acid was replaced with the recovered hydrochloric acid (hydrochloric acid concentration: 19% by mass) after solid-liquid separation in Example 2.

Example 4
A titanium concentrate was obtained in the same manner as in Example 2, except that the 20% by mass hydrochloric acid was replaced with the recovered hydrochloric acid (hydrochloric acid concentration: 17% by mass) after solid-liquid separation in Example 3.

Example 5
A titanium concentrate was obtained in the same manner as in Example 2, except that the 20% by mass hydrochloric acid was replaced with the recovered hydrochloric acid after solid-liquid separation in Example 4 (hydrochloric acid concentration: 15% by mass).

Example 6
A titanium concentrate was obtained in the same manner as in Example 1, except that the mixture was heated without being stirred and mixed.

Example 7
A titanium concentrate was obtained in the same manner as in Example 1, except that the titanium-containing material was ground in advance with a ball mill and the leaching time was set to 7 hours.

Comparative example 1
A titanium concentrate was obtained in the same manner as in Example 1, except that ilmenite ore having the composition shown in Table 2 was used instead of the low-grade titanium concentrate, and the ilmenite ore and 20 mass% hydrochloric acid were mixed so that V/W = 6 (L/kg).

Table 3 shows the results of component analysis of the titanium concentrates obtained in Examples and Comparative Examples.

While the TiO ₂ grade of the titanium concentrate of Comparative Example 1 is 84.9% by mass, the TiO ₂ grade of the titanium concentrates of Examples 1 to 7 is 93.6 to 95.1% by mass, exceeding 93% by mass. It can be seen that in Comparative Example 1, even if a large amount of hydrochloric acid (V/W=6) is used, a high-grade titanium concentrate cannot be obtained. Moreover, in the examples, since a low-grade titanium concentrate is used, it was confirmed that a high-grade titanium concentrate containing only titanium oxide having a rutile structure can be produced in the drying stage.

The method for producing a titanium concentrate of the present invention can remove impurities from a titanium-containing material even by using a small amount of a hydrochloric acid-containing leaching solution, so that a high-quality titanium concentrate can be produced in a simple and efficient manner. In addition, since the used leaching solution containing hydrochloric acid can be recovered and reused, a large-scale waste acid treatment facility becomes unnecessary.

Claims (13)

A method for producing a titanium concentrate, comprising a leaching step of adding a hydrochloric acid-containing leachate (volume V (L)) having an initial hydrochloric acid concentration of 15% by mass or more and a titanium-containing material (mass W (kg)) to a reaction vessel so that V/W is 3.0 (L/kg) or less, and heating the hydrochloric acid-containing leachate to 80° C. or higher to leach impurities from the titanium-containing material. 2. The method for producing a titanium concentrate according to claim 1, wherein the hydrochloric acid-containing leachate is hydrochloric acid or recovered hydrochloric acid. 3. The method for producing a titanium concentrate according to claim 2, wherein the recovered hydrochloric acid is recovered by solid-liquid separation of the slurry after the leaching step with hydrochloric acid. 3. The method for producing a titanium concentrate according to claim 2, wherein the recovered hydrochloric acid is a multiple times recovered hydrochloric acid obtained by repeating an operation of solid-liquid separation and recovery of the slurry after the leaching step with the recovered hydrochloric acid. The method for producing a titanium concentrate according to any one of claims 1 to 4, wherein the hydrochloric acid-containing leachate has an initial hydrochloric acid concentration of 15 to 25% by mass. The method for producing a titanium concentrate according to any one of claims 1 to 5, comprising a step of solid-liquid separation of the slurry after the leaching step, and washing and drying the collected solid matter. 7. The method for producing a titanium concentrate according to claim 6, further comprising a step of classifying or granulating after the washing and drying steps. The method for producing a titanium concentrate according to any one of claims 1 to 7, comprising a step of calcining the solid after the washing and drying steps. The production method according to any one of claims 1 to 8, wherein the leaching step is performed at a reaction temperature below the boiling point of the hydrochloric acid-containing leaching solution. A method for producing a titanium concentrate according to any one of claims 1 to 9, wherein the titanium-containing material has a TiO ₂ grade of 70 to 90 mass%. The method for producing a titanium concentrate according to claim 10, wherein the titanium-containing material has a TiO ₂ grade of 80-90 wt%. The method for producing a titanium concentrate according to any one of claims 1 to 11, wherein the titanium concentrate obtained has a TiO ₂ grade of 93% by mass or more. 13. The method for producing a titanium concentrate according to claim 12, wherein the titanium concentrate obtained has a _TiO2 grade of 95% by mass or more.