Method for producing titanium smelting raw material

Abstract

To provide a method for producing a titanium smelting raw material by which impurities can be separated and removed from ilmenite ore at a low cost in a short time.SOLUTION: An ammonium salt as a reactant is mixed with a pulverized product of ilmenite ore to form a mixture, and the mixture is heat-treated to obtain a reaction product, which is then dissolved in a solvent to form a suspension. A precipitate containing high-concentration TiO2 can be obtained by solid-liquid separation into a solid residue and a leachate and heating the leachate. The stepwise calcination of the precipitate makes it possible to produce anatase and rutile, respectively, with a high TiO2 concentration.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a titanium smelting raw material, and more particularly to a method for producing a titanium smelting raw material that can separate and remove impurities from ilmenite ore at low cost and in a short time. [Background technology]

[0002] Titanium is lightweight yet has excellent strength, heat resistance, and corrosion resistance, as well as properties such as non-magnetic properties and high biocompatibility, and is used as a metal or alloy in a variety of fields, from aircraft, automobiles, and chemical plants to sporting goods and eyeglass frames. Furthermore, because titanium is less likely to cause metal allergies and does not accumulate in the body and become toxic, it has recently been attracting attention as a material and device for medical applications such as artificial tooth roots (implants), artificial bones, and artificial joints.

[0003] On the other hand, high-grade rutile ore (TiO2) with a high titanium content is becoming scarce worldwide, and is becoming difficult to obtain due to the recent rise in raw material prices. In this context, as an alternative raw material to high-grade rutile ore, ilmenite ore, which is relatively inexpensive and has abundant reserves, is being processed to increase its titanium content (hereinafter referred to as "upgrading" or "upgrading") and used as a raw material for smelting high-grade titanium.

[0004] Known methods for upgrading ilmenite ore include the chlorine method in which ilmenite ore is leached in chlorine and the sulfuric acid method in which ilmenite ore is leached in sulfuric acid, as shown in Patent Document 1 and Non-Patent Document 1, for example.

[0005] Another known method, as shown in Non-Patent Document 2, is the titanium slag process, in which ilmenite ore is melted and reduced in a blast furnace, electric arc furnace, or the like to produce pig iron, and titanium oxide is collected in slag, which is used as a titanium smelting raw material. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-105457 [Non-patent literature]

[0007] [Non-Patent Document 1] Keiichi Murakami, "Utilization of Titanium Slag," Journal of the Japan Institute of Metals, Vol. 3 (1964) No. 6, p. 292-302 [Non-patent document 2] Tadao Tomonari, "Titanium Industry and Its Outlook," 1st Edition, Japan Titanium Society, January 10, 2001, p.4 Summary of the Invention [Problem to be solved by the invention]

[0008] Among the above-mentioned conventional techniques, the chlorine method consumes chlorine to remove impurities, and there are also concerns that the amount of waste increases, that flow is poor in the chlorination furnace, and that the chlorides produced may clog pipes, and the sulfuric acid method has the problem of a long treatment time.

[0009] Furthermore, in the titanium slag method, the titanium slag must be heat-treated together with a reducing agent in a high-temperature furnace, which increases the processing cost.

[0010] In response to the above-mentioned problems, the inventors of the present application discovered that by mixing ilmenite ore with an ammonium salt containing ammonium hydrogen sulfate or ammonium sulfate and heating the mixture, the ammonium salt converts the various oxides contained in the ilmenite ore, including TiO2 and FeO, into a molten salt, and further developed a method for producing a titanium smelting raw material that enables the easy extraction of only TiO2 from the resulting molten salt. [Means for solving the problem]

[0011] In order to achieve the above object, the method for producing a titanium smelting raw material of the present invention comprises the steps of mixing ilmenite ore with a predetermined amount of ammonium salt as a reactant to produce a mixture and heating the mixture under predetermined heating conditions; dissolving the reactant obtained in the heating step in a predetermined solvent to produce a suspension; separating the suspension into a solid residue and a leachate; and heating the leachate under predetermined heating conditions to obtain a precipitate.

[0012] Here, by providing a step of mixing ilmenite ore with a predetermined amount of ammonium salt as a reactant to generate a mixture, and then heating the mixture under predetermined heating conditions, the ammonium salt as a reactant acts on the ilmenite ore, thereby converting various oxides contained in the ilmenite ore into molten salts that are soluble in water.

[0013] Furthermore, when the ammonium salt is at least one selected from ammonium hydrogen sulfate and ammonium sulfate, the ilmenite ore can be easily converted into a melt due to its high reactivity with the ilmenite ore.

[0014] Furthermore, by providing a step of dissolving the reaction product obtained in the heating step in a predetermined solvent to produce a suspension, the reaction product can be dissolved in a solvent such as water. In this case, since the molten salt is soluble in water as described above, it can be easily dissolved in the solvent.

[0015] Furthermore, by providing a step of solid-liquid separation of the suspension into a solid residue and a leachate, the suspension can be separated into the solid residue and the leachate. At this time, the titanium (Ti) component of the molten salt is dissolved in the leachate, and as described below, a precipitate containing a high concentration of TiO2 can be obtained from the leachate after solid-liquid separation.

[0016] Furthermore, by providing a step of heating the leachate under predetermined heating conditions to obtain a precipitate, titanium hydroxide (TiO(OH)2) precipitates through a hydrolysis reaction by heating the leachate, forming a new suspension, from which a precipitate containing high concentrations of TiO2 can be obtained. Through the above steps, iron components can be separated and removed from the ilmenite, and high concentrations of TiO2 can be extracted.

[0017] Furthermore, when the ammonium salt is mixed in a weight ratio of 2 to 30 times that of the ilmenite ore, the reaction of the mixture is promoted and the mixture can be melted efficiently. Note that when the weight ratio of the ammonium salt to the ilmenite ore is less than 2 times, the reaction of the mixture is not promoted and not all of the mixture can be melted. On the other hand, when the weight ratio of the ammonium salt to the ilmenite ore exceeds 30 times, there is no change in the reaction time, so in consideration of processing costs, it is preferable that the upper limit of the weight ratio of the ammonium salt to the ilmenite ore is about 30 times.

[0018] Furthermore, in the step of heating the mixture under predetermined heating conditions, if the mixture is heated to a temperature of 150 to 510°C, the reaction by the ammonium salt is promoted and the mixture can be melted efficiently. Note that, if the mixture temperature is heated under heating conditions of less than 150°C, the reaction does not proceed and the mixture does not reach a completely molten state. Furthermore, since the boiling point of the molten salt is approximately 510°C, the heating conditions for the mixture are preferably 150 to 510°C.

[0019] The solvent is selected from pure water, tap water, ion-exchanged water, distilled water, sulfuric acid, hydrochloric acid, and aqueous ammonia, and when the pH of the suspension is 1 to 4, these dissolving solutions can leave the Fe component contained in the mixture as a residue and leach the Ti component into the solvent. Note that when the pH of the suspension after dissolution is less than 1, the leaching rate of the Fe component into the solvent increases, and when the pH exceeds 4, the leaching rate of the Ti component into the solvent decreases.

[0020] Furthermore, in the step of heating the leachate under predetermined heating conditions to obtain a precipitate, if the leachate is heated to a temperature of 40 to 100°C, a precipitate containing a Ti component can be efficiently precipitated from the leachate in a short period of time.

[0021] Furthermore, when the step of heating the leachate under predetermined heating conditions to obtain a precipitate includes a step of solid-liquid separation of the heated leachate, by heating the leachate, a precipitate containing a high concentration of TiO2 can be easily obtained from a suspension in which titanium hydroxide (TiO(OH)2) has precipitated by a hydrolysis reaction.

[0022] Furthermore, when a calcination step is further provided to raise the temperature of the precipitate to 700 to 1000°C, anatase crystals begin to grow at about 700°C and are completely transformed into rutile at 1000°C. In this way, stepwise calcination of the precipitate makes it possible to produce both anatase and rutile, each of which is composed of high-concentration TiO2. [Effects of the Invention]

[0023] The method for producing a titanium smelting raw material according to the present invention is capable of separating and removing impurities from ilmenite ore at low cost and in a short time. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a process diagram showing a method for producing a titanium smelting raw material according to an embodiment of the present invention. [Figure 2] 1 is a photograph showing the appearance of a crushed product obtained by crushing ilmenite ore in an example. [Figure 3] 1 is a photograph showing the appearance of a mixture of ilmenite ore and ammonium hydrogen sulfate in an example. [Figure 4] 1 is a photograph showing the appearance of a melt produced by heating a mixture in an example. [Figure 5] 1 is a graph showing the relationship between the melting time of the mixture and the leaching rate of the Ti component. [Figure 6]1 is a graph showing the relationship between the pH of a suspension and the leaching rate of a Ti component and an Fe component. [Figure 7] 1 is a photograph showing the appearance of a leachate after solid-liquid separation in an example. [Figure 8] 1 is a graph showing the results of XRD analysis of the solid residue obtained by solid-liquid separation. [Figure 9] 1 is a photograph showing the appearance of the infusion liquid after heating in an example. [Figure 10] 1 is a photograph showing the appearance of a precipitate in an example. [Figure 11] 1 is a graph showing the results of XRD analysis of precipitates. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, a method for producing a titanium smelting raw material according to an embodiment of the present invention will be described in detail with reference to the drawings etc. to facilitate understanding of the present invention.

[0026] Fig. 1 shows a process flow diagram illustrating a method for producing a titanium smelting raw material according to an embodiment of the present invention. The method for producing a titanium smelting raw material according to this embodiment mainly comprises a series of steps: mixing pulverized ilmenite ore with an ammonium salt reactant to produce a mixture (step 1), heat-treating the mixture (step 2), dissolving the molten material (reactant) obtained by the heat treatment in step 2 in a solvent to produce a suspension (step 3), separating the suspension produced in step 3 into a solid residue and a leachate (step 4), and further heating the separated leachate to obtain a precipitate (step 5).

[0027] The ilmenite ore in step 1 is previously pulverized in a pulverizer to a powder of a predetermined particle size. Then, this pulverized material is mixed with ammonium salt, which is a reactant. The ammonium salt is mixed in an amount of approximately 2 to 30 times the weight of the pulverized material.

[0028] Here, if the amount of ammonium salt mixed is less than approximately twice the weight of the crushed material, when the mixture is heat-treated, the crushed ilmenite ore will not be completely immersed in the molten ammonium salt, the reaction between the crushed material and the ammonium salt will not be promoted, and all of the crushed material will not be melted.

[0029] On the other hand, even if the amount of ammonium salt mixed exceeds approximately 30 times the weight of the pulverized material, no significant change in reaction time is observed. Therefore, taking into consideration the processing cost, it is preferable that the upper limit of the weight ratio of ammonium salt to pulverized material is approximately 30 times.

[0030] The heating conditions in step 2 can be changed as appropriate depending on the boiling point of the ammonium salt used as the reactant. For example, when ammonium hydrogen sulfate (NH4HSO4) is used as the ammonium salt, the heating conditions are adjusted so that the temperature is 150°C or higher, which is higher than the melting point of ammonium hydrogen sulfate. When the ammonium hydrogen sulfate begins to melt, the reaction with the ilmenite ore is promoted, and various oxides contained in the ilmenite ore, such as TiO2 and FeO, begin to dissolve, converting the ore into a molten salt.

[0031] Regarding the heating conditions, if the temperature of the mixture is less than 150°C, the ammonium hydrogen sulfate does not melt completely, and the reaction with the crushed material is not promoted, so the ore components of the ilmenite ore cannot be converted into molten salt. The upper limit of the heating temperature can be set near the boiling point of the molten salt (approximately 510°C).

[0032] When ammonium sulfate ((NH4)2SO4) is used as the ammonium salt, it liquefies at approximately 120°C or higher and begins to react with ilmenite ore, changing into ammonium hydrogen sulfate at approximately 150°C, after which the reaction proceeds in the same way as when ammonium hydrogen sulfate is used.

[0033] In step 3, the melt (reactant) obtained in step 2 is cooled, and then the solidified melt is dissolved in a predetermined solvent to produce a suspension. At this time, since the various oxides contained in the ilmenite ore have been converted into molten salts by step 2, the solidified melt can be easily dissolved in the solvent.

[0034] The solvent used for dissolution can be appropriately selected from, for example, pure water, tap water, ion-exchanged water, distilled water, sulfuric acid, hydrochloric acid, aqueous ammonia, etc., and the pH of the suspension is preferably in the range of 1 to 4.

[0035] The pH of the suspension is not limited to the aforementioned range of pH 1 to 4. However, as a result of repeated investigations by the inventors, it was found that when the pH of the suspension is less than 1, the rate of leaching of the Fe component into the solvent increases, resulting in an increase in the Fe component contained in the precipitate obtained in step 5 described below. On the other hand, when the pH of the suspension exceeds 4, the rate of leaching of the Ti component into the solvent decreases. Therefore, in order to obtain a high-quality titanium smelting raw material, it is preferable that the pH of the suspension produced in step 3 be in the range of 1 to 4.

[0036] In step 3, the melt obtained in step 2 may be added dropwise in small amounts to a solvent prepared in advance in the state of the melt after heating, without being cooled, to form a suspension.

[0037] In step 4, the suspension produced in step 3 is subjected to solid-liquid separation. By the solid-liquid separation, the suspension can be separated into a leachate containing Ti components and a solid residue containing Fe components.

[0038] The solid residue obtained by solid-liquid separation may still contain Ti components, so the solid residue is dried and then mixed with ammonium salt again to repeat the reaction, thereby extracting the Ti components from the solid residue and further increasing the recovery rate of Ti components from ilmenite ore.

[0039] In step 5, the leachate obtained in step 4 is heated under predetermined heating conditions to obtain a precipitate. This precipitate is further calcined to obtain a high-quality titanium smelting raw material with a high Ti concentration. [Example]

[0040] Next, examples of the present invention will be described, but the present invention is not limited to the descriptions of these examples.

[0041] 1. Advance preparation First, as a preliminary preparation, ilmenite ore was crushed to a particle size of approximately 53 μm (Fig. 2). 0.1 g of crushed ilmenite ore and 1.5 g of ammonium hydrogen sulfate, a reactant, were prepared and mixed together (hereinafter, the mixture of crushed ilmenite ore and ammonium hydrogen sulfate will be referred to as the "mixture") and placed in a test tube (Fig. 3).

[0042] 2. Melt generation The test tube was attached to a rotary evaporator and heated at a speed of 50 rpm with a gas burner for approximately 20 minutes. The reaction began approximately one minute after heating began, after which the entire mixture melted and the residue became suspended. After approximately 20 minutes, the mixture in the test tube became completely molten (Figure 4).

[0043] Figure 5 shows the results of an investigation into the relationship between the melting time (heating time) and the leaching rate of the Ti element into the solvent, which will be described later. As shown in Figure 5, if the melting time is short, the reaction between the ilmenite ore and ammonium hydrogen sulfate becomes incomplete, resulting in a low leaching rate of the Ti element. Therefore, in order to increase the leaching rate of the Ti element into the solvent, it is necessary to ensure a sufficient melting time.

[0044] 3. Solvent dissolution The test tube was allowed to cool to room temperature, whereupon the molten salt solidified. 30 ml of ion-exchanged water was then added to the test tube, and the mixture was stirred using a vortex mixer until the solidified molten salt was completely dissolved in the solvent, forming a suspension. The pH of the resulting suspension was 1.4.

[0045] Figure 6 shows the results of an investigation into the leaching rate of Ti and Fe components into the solvent at different pH levels in the suspension. The solvents used were hydrochloric acid, ion-exchanged water, and ammonia water, and the pH in the figure is the measured value of the suspension after the melt had dissolved in the solvent. As shown in Figure 6, when the pH of the suspension is 1.4, the leaching rate of the Ti component into the solvent is high, but conversely, the leaching rate of the Fe component into the solvent can be suppressed, allowing the Ti and Fe components to be separated efficiently.

[0046] On the other hand, if the pH of the suspension is less than 1, the leaching rate of the Ti component increases, but the leaching rate of the Fe component also increases, making it impossible to separate the Ti and Fe components. Furthermore, if the pH of the suspension exceeds 4, the leaching rates of both the Ti and Fe components decrease, making it impossible to separate the Ti and Fe components. From the above, it can be seen that the pH of the suspension is preferably about 1 to 4.

[0047] 4.Solid-liquid separation The suspension obtained by dissolving in the solvent separated into a solid residue and a leachate (Figure 7).

[0048] Figure 8 shows the results of XRD (X-ray diffraction) analysis of the solid residue obtained by solid-liquid separation. The solid line in the figure shows the XRD measurement results of the solid residue, and the "●" symbol indicates the peak position of NH4Fe(SO4)2.

[0049] As shown in Figure 8, only the Fe element was confirmed in the form of a salt in the solid residue, and the Ti element appears to have leached into the solvent side, which indicates that ammonium hydrogen sulfate acted on the ilmenite ore.

[0050] 5.Precipitation Next, the leachate obtained by solid-liquid separation was heated on a hot plate set at 200°C for 30 minutes, causing the leachate to become cloudy (Figure 9). The cloudy leachate was subjected to solid-liquid separation and then dried to obtain a precipitate (Figure 10).

[0051] Figure 11 shows the results of XRD analysis of a sample of the obtained precipitate that was dried, and a sample that was calcined stepwise at temperatures ranging from 500 to 1000°C. The solid lines in the figure show the XRD measurement results for the precipitate in each temperature range, and the symbols "▼" and "●" in the figure indicate the representative peak positions of anatase and rutile, respectively, as reference values.

[0052] First, at 500°C, a small amount of anatase crystals was present among the broad peaks. When heated further, anatase crystals grew, and growth was complete when the temperature reached 700°C. When the temperature reached 800°C, rutile crystals grew, while the anatase crystals decreased. When heated to 1000°C, the crystals completely transformed into rutile.

[0053] From the above, it is considered that the precipitate is TiO2 with an amorphous structure. It was also shown that it is possible to produce anatase and rutile by controlling the calcination temperature.

[0054] The TiO2 weight ratios of the ilmenite ore and precipitates are shown in Table 1. As shown in Table 1, the TiO2 ratio in the precipitates is significantly improved, and by applying this invention, it has been possible to separate and remove impurities, including Fe components, and to upgrade the ilmenite ore.

[0055] [Table 1]

[0056] As described above, the method for producing a titanium smelting raw material according to the present invention can separate and remove impurities from ilmenite ore at low cost in a short period of time.

Claims

1. a step of mixing ilmenite ore with a predetermined amount of ammonium salt as a reactant to generate a mixture, and heating the mixture under predetermined heating conditions; a step of dissolving the reaction product obtained in the heating step in a predetermined solvent to form a suspension; subjecting the suspension to solid-liquid separation into a solid residue and a leachate; and a step of heating the leachate under predetermined heating conditions to obtain a precipitate. A method for manufacturing titanium smelting raw materials.

2. The ammonium salt is selected from ammonium hydrogen sulfate or ammonium sulfate. At least one of the following The method for producing a titanium smelting raw material according to claim 1.

3. The ammonium salt is mixed in an amount of 2 to 30 times by weight relative to the ilmenite ore. The method for producing a titanium smelting raw material according to claim 1 or 2.

4. The step of heating the mixture under predetermined heating conditions involves heating the mixture to a temperature of 150 to 510°C. The method for producing a titanium smelting raw material according to claim 1 or 2.

5. the solvent is selected from the group consisting of pure water, tap water, ion-exchanged water, distilled water, sulfuric acid, hydrochloric acid, and aqueous ammonia; The pH of the suspension is in the range of 1 to 4. The method for producing a titanium smelting raw material according to claim 1 or 2.

6. In the step of heating the leachate under predetermined heating conditions to obtain a precipitate, the leachate is heated to a temperature of 40 to 100°C. The method for producing a titanium smelting raw material according to claim 1 or 2.

7. The step of heating the leachate under predetermined heating conditions to obtain a precipitate includes: A step of subjecting the leachate after heating to solid-liquid separation is included. The method for producing a titanium smelting raw material according to claim 1 or 2.

8. The method further includes a step of calcining the precipitate to a temperature of 700 to 1000°C. The method for producing a titanium smelting raw material according to claim 1 or 2.

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