Method for preparing raw material for fluidized chlorination by using titanium slag

Abstract

The present application relates to the technical field of metallurgy and chemical industry, and particularly relates to a method for preparing boiling chlorination raw material from titanium slag. The method for preparing boiling chlorination raw material from titanium slag comprises the following steps: S1, pre-treating water-quenched titanium slag at 150-550 DEG C to obtain pre-treated titanium slag; S2, sequentially performing pre-leaching treatment and acid leaching treatment on the pre-treated titanium slag to obtain boiling chlorination raw material. The present application adds a low-temperature pre-treatment step before leaching of the water-quenched titanium slag, reduces the loss of titanium, effectively avoids the pulverization of the product in the subsequent leaching process, improves the titanium yield while ensuring the leaching effect of other impurity elements, reduces the amount of fine powder in the product, thereby improving the grade of TiO2 and meeting the requirements of boiling chlorination raw material; and the preparation method has a short process flow, simple steps and high TiO2 yield.

Description

Technical Field

[0001] This invention relates to the fields of metallurgy and chemical technology, and in particular to a method for preparing fluidized bed chlorination feedstock from titanium slag. Background Technology

[0002] Titanium dioxide is one of the best-performing white pigments currently available and is widely used in industries such as coatings, plastics, papermaking, printing inks, synthetic fibers, rubber, and cosmetics. Industrial production methods for titanium dioxide include the sulfuric acid process and the chlorination process. The sulfuric acid process has a long production cycle, produces lower quality products, and is prone to pollution. The chlorination process is more environmentally friendly, but it has very stringent requirements for raw materials, requiring a high TiO2 content. This is because impurities such as CaO and MgO generate low-melting-point, high-boiling-point chlorides during chlorination, which deteriorates the fluidity of the fluidized bed in the boiling chlorination furnace.

[0003] Currently, there are three industrial methods for producing titanium-rich materials for large-scale fluidized bed chlorination: electric furnace method, acid leaching method, and reduction etching method. These three methods all have high requirements for raw materials, primarily requiring high-quality placer ore resources with low impurity content. However, high-quality ilmenite placer ore resources are relatively scarce, while ilmenite rock resources are relatively abundant. Therefore, improving the utilization value of low-quality titanium resources and processing them into high-quality titanium-rich materials for large-scale fluidized bed chlorination is of great significance.

[0004] The utilization methods for low-quality titanium resources mainly focus on two directions: the combined method of electric furnace smelting of titanium concentrate and upgrading titanium slag, and the direct upgrading of titanium concentrate to synthetic rutile. Among them, the direct upgrading of titanium concentrate to synthetic rutile is relatively simple, but it suffers from serious problems with unqualified product particle size. The combined method of electric furnace smelting and upgrading titanium slag can effectively solve the problem of fine product particle size, but it has the problems of high process difficulty and high cost.

[0005] The preparation of titanium-rich materials using low-quality titanium resources presents the following problems: poor product quality, fine particle size, severe pulverization, and a low percentage of the product suitable for direct use in fluidized bed chlorination, requiring further granulation to meet the requirements; significant titanium loss during preparation, resulting in low yield; long and complex process flow, poor economic efficiency, secondary pollution, and high production costs.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing fluidized bed chlorination feedstock from titanium slag, which can reduce the impurity content in titanium slag and the amount of fine powder in the product, and improve the grade of TiO2, thereby meeting the requirements of fluidized bed chlorination feedstock; moreover, the preparation method has a short process flow, simple steps, and high TiO2 yield.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0009] This invention provides a method for preparing fluidized bed chlorination feedstock from titanium slag, comprising the following steps:

[0010] S1. Water-quenched titanium slag is pretreated at 150-550℃ to obtain pretreated titanium slag.

[0011] S2. The pretreated titanium slag is subjected to pre-leaching and acid leaching treatments in sequence to obtain boiling chlorination raw material.

[0012] Further, in step S1, the water-quenched titanium slag contains TiO2 at a content of 70 wt.% to 85 wt.%, CaO at a content of ≥0.2 wt.%, and MgO at a content of ≥2 wt.%.

[0013] Preferably, in step S1, the particle size of the water-quenched titanium slag is 20-160 mesh.

[0014] Furthermore, in step S1, the pretreatment includes oxidative roasting.

[0015] Preferably, in step S1, the pretreatment time is 0.5 to 4 hours.

[0016] Furthermore, in step S1, the content of low-valent titanium in the pretreated titanium slag is ≤0.5 wt.%.

[0017] Further, in step S2, the pre-leaching treatment includes acid leaching a mixture of pretreated titanium slag and a first acid solution to obtain leaching residue.

[0018] Preferably, in step S2, the temperature of the pre-soaking treatment is 20–100°C, and the time of the pre-soaking treatment is 20–120 min.

[0019] Further, in step S2, the mass ratio of the first acid solution to the pretreated titanium slag is (0.5~2):1.

[0020] Preferably, in step S2, the mass concentration of the first acid solution is 5% to 30%.

[0021] Further, in step S2, the acid leaching treatment includes pressurized acid leaching of the mixture of the leaching residue and the second acid solution.

[0022] Furthermore, in step S2, the temperature of the acid leaching treatment is 130–175°C, and the time of the acid leaching treatment is 0.5–6 hours.

[0023] Preferably, in step S2, the pressure of the acid leaching treatment is 0.2 to 0.9 MPa.

[0024] Further, in step S2, the mass ratio of the second acid solution to the leaching residue is (1-5):1.

[0025] Preferably, in step S2, the mass concentration of the second acid solution is 13% to 30%.

[0026] Further, in step S2, the first acid solution and the second acid solution each independently include at least one of hydrochloric acid, nitric acid, acetic acid, sulfuric acid and hydrofluoric acid.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] The method for preparing fluidized bed chlorination feedstock from titanium slag of the present invention reduces the amount of fine powder in the product by reducing the impurity content in the titanium slag, thereby improving the TiO2 grade and meeting the requirements of fluidized bed chlorination feedstock. It can obtain fluidized bed chlorination feedstock with a fine powder rate ≤5%, TiO2 content ≥85wt.%, CaO content ≤0.1wt.%, and total CaO and MgO content ≤1.5wt.%.

[0029] The preparation method of the present invention reduces the loss of titanium, and the yield of TiO2 is ≥90%; moreover, the process is short, the cost is low, and the adaptability to raw materials is wider.

[0030] This invention significantly reduces the content of low-valent titanium in water-quenched titanium slag by adding a low-temperature (150-550℃) pretreatment step before leaching, ensuring that no trivalent titanium enters the mother liquor during the subsequent leaching process, thus reducing titanium loss; it also strengthens the skeletal structure of the water-quenched titanium slag and greatly eliminates low-valent titanium in the slag, effectively preventing product pulverization during the subsequent leaching process. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 The image shows the XRD patterns of water-quenched titanium slag after pretreatment at different temperatures according to the present invention.

[0033] Figure 2 This invention relates to the effect of pretreatment temperature on TiO2 yield and CaO / MgO content after pressurized acid leaching. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0035] The following is a detailed description of an embodiment of the present invention for preparing a boiling chlorination feedstock from titanium slag.

[0036] In some embodiments of the present invention, a method for preparing fluidized bed chlorination feedstock from titanium slag is provided, comprising the following steps:

[0037] S1. Pre-treat the water-quenched titanium slag at 150-550℃ to obtain pre-treated titanium slag.

[0038] S2. The pretreated titanium slag is subjected to pre-leaching and acid leaching treatments in sequence to obtain the fluidized bed chlorination raw material.

[0039] This invention adds a low-temperature pretreatment step to the water-quenched titanium slag before the leaching process. This not only disrupts the black titanium stone structure in the slag but also oxidizes low-valent titanium to tetravalent titanium, ensuring that no trivalent titanium enters the mother liquor during the subsequent leaching process, reducing titanium loss. This improves titanium yield while also ensuring the effective leaching of other impurities. The low-temperature pretreatment step strengthens the skeletal structure of the water-quenched titanium slag and significantly eliminates low-valent titanium, effectively preventing product pulverization during subsequent leaching.

[0040] Compared to other processes for removing impurities such as calcium and magnesium (such as oxidation-reduction-acid leaching), the process of this invention is shorter, lower in cost, and more adaptable to raw materials. Water-quenched titanium slag can remove impurities such as calcium and magnesium through pretreatment and leaching processes.

[0041] The present invention provides a method for preparing fluidized bed chlorination feedstock using titanium slag as raw material, comprising pretreatment, pre-leaching treatment and acid leaching treatment of water-quenched titanium slag in sequence.

[0042] Pretreatment is crucial. Water-quenched titanium slag, due to its poor crystallinity and numerous pores, exhibits excellent acid solubility. While direct acid leaching effectively removes harmful impurities such as calcium, magnesium, and aluminum, it results in significant titanium loss. Low-temperature pretreatment oxidizes the low-valent titanium in the water-quenched slag to TiO2, significantly reducing the acid solubility of this titanium. Simultaneously, to ensure the leaching of impurity elements, the Fe content in the slag must be controlled.2+ Oxidation of Fe, if the pretreatment temperature is too high, will lead to Fe oxidation. 2+ Oxidized to Fe 3+ This leads to the formation of Fe2TiO5, which has extremely poor acid solubility, with the titanium phase, resulting in low leaching rates of impurities such as calcium and magnesium. Simultaneously, the heating pretreatment affects the leaching rate of Ca; the higher the pretreatment temperature, the lower the leaching rate of Ca. This is mainly because amorphous CaSi2O5 transforms into crystalline CaSi2O5, which has poor acid solubility, upon heating.

[0043] Pre-leaching treatment: After pretreatment, water-quenched titanium slag still contains a small amount of metallic iron. During acid leaching, the metallic iron reacts with acid to generate free hydrogen. This free hydrogen can reduce the tetravalent titanium in the titanium slag to trivalent titanium. However, the acid concentration in the reaction system is relatively high during acid leaching. Under high acidity, trivalent titanium cannot be hydrolyzed and precipitated, resulting in titanium loss into the solution and a low TiO2 yield. To avoid the influence of this metallic iron, the reaction system needs to be pre-leached before acid leaching.

[0044] Acid leaching treatment: The acid leaching process can further destroy the structure of the black titanium stone in the titanium slag, thereby removing impurities such as calcium and magnesium, and selectively dissolving these impurities. One of the main chemical reactions that occurs during acid leaching is as follows: CaSi₂O₅ + 2H₂O + →Ca 2+ +H2Si2O5.

[0045] In the method for preparing boiling chlorination feedstock from titanium slag, Ca in the water-quenched slag mainly exists in the form of CaSi2O5. CaSi2O5 and glassy substances are mutually fused to form a complex. Both CaSi2O5 and glassy substances are easily soluble in acid. Magnesium mainly exists in the structure of zeolite. By destroying the structure of zeolite through low-temperature pretreatment, pre-leaching treatment and acid leaching treatment, it can be further removed. Titanium mainly exists in the zeolite or rutile phase and is not easily leached, thus ensuring a high TiO2 yield.

[0046] In some embodiments of the present invention, in step S1, the boiling chlorination feedstock refers to titanium-rich feedstock used in the boiling chlorination process.

[0047] In some embodiments of the present invention, step S1, the method for preparing water-quenched titanium slag includes: mixing molten titanium slag with water quenching liquid, and then water quenching to obtain water-quenched titanium slag.

[0048] In some embodiments of the present invention, in step S1, the water quenching solution includes at least one of water, an acidic solution, and an alkaline solution; preferably water; more preferably, the water quenching pressure is 1 to 40 kg·f / cm². 2 .

[0049] In some specific embodiments of the present invention, in step S1, the molten titanium slag is mainly obtained by mixing and smelting titanium-containing iron concentrate and a reducing agent.

[0050] Water-quenched titanium slag is obtained by rapidly cooling molten titanium slag with high-pressure water quenching liquid. After being rapidly cooled by high-speed water flow, the atoms or ions in the slag solidify before they can form regularly arranged crystals, resulting in poor crystallinity. Furthermore, the rapid cooling causes changes in the phase structure of the titanium slag; some of the rutile structures become rutile, and a significant amount of glassy material is formed. Due to the combined effects of high-pressure water impact and cooling internal stress, numerous pores are formed inside the water-quenched slag. This allows acid to diffuse more easily into the interior of the slag during acid leaching, facilitating the leaching of impurities. It was also found that Ca in the water-quenched titanium slag mainly exists in the form of CaSi₂O₅. CaSi₂O₅ and glassy material are interwoven to form a complex, with the rutile structure interwoven and evenly dispersed within the complex. CaSi₂O₅ is a highly acid-soluble substance and can be easily removed during acid leaching.

[0051] In some embodiments of the present invention, in step S1, the water-quenched titanium slag contains TiO2 content of 70 wt.% to 85 wt.%, CaO content of ≥0.2 wt.%, and MgO content of ≥2 wt.%.

[0052] In some embodiments of the present invention, in step S1, the particle size of the water-quenched titanium slag is 20-160 mesh.

[0053] In some embodiments of the present invention, step S1 includes oxidative roasting.

[0054] In some embodiments of the present invention, in step S1, the pretreatment temperature is 150–550°C, and the pretreatment time is 0.5–4 h; typically, but not limitingly, for example, the pretreatment temperature is a range of 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, or any combination thereof; and the pretreatment time is a range of 0.5 h, 1 h, 1.5 h, 2 h, 3.5 h, 4 h, or any combination thereof.

[0055] In some embodiments of the present invention, in step S1, the volume content of oxygen in the furnace during the pretreatment process is ≥5%; preferably, the volume content of oxygen in the furnace during the pretreatment process is 10% to 20%. During the pretreatment process, exhaust gas and air after the combustion of the substance are introduced into the furnace, such as gas and air after the combustion of natural gas, thereby controlling the oxygen content in the furnace.

[0056] In some embodiments of the present invention, in step S1, the content of low-valent titanium in the pretreated titanium slag is ≤0.5 wt.%. Low-valent titanium is titanium with a +3 valence.

[0057] In some embodiments of the present invention, step S2, the pre-leaching treatment includes acid leaching a mixture of pretreated titanium slag and a first acid solution to obtain leaching residue.

[0058] Pre-immersion treatment mainly removes metallic iron from the pretreated titanium slag.

[0059] In some embodiments of the present invention, in step S2, the temperature of the pre-immersion treatment is 20–100°C, and the pre-immersion treatment time is 20–120 min; typically, but not limitingly, for example, the pre-immersion treatment temperature is a range of 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or any combination thereof; the pre-immersion treatment time is a range of 20 min, 40 min, 60 min, 80 min, 100 min, 120 min, or any combination thereof; preferably, the pre-immersion treatment temperature is 50–100°C.

[0060] In some embodiments of the present invention, in step S2, the pre-immersion treatment includes any one of stirred leaching, column leaching, and heap leaching.

[0061] In some embodiments of the present invention, in step S2, the mass ratio of the first acid solution to the pretreated titanium slag is (0.5 to 2):1; typically, but not limitingly, for example, the mass ratio of the first acid solution to the pretreated titanium slag is 0.5:1, 1:1, 1.5:1, 2:1 or any combination thereof; preferably, the mass ratio of the first acid solution to the pretreated titanium slag is (1 to 2):1.

[0062] In some embodiments of the present invention, in step S2, the mass concentration of the first acid solution is 5% to 30%; typically, but not limitingly, for example, the mass concentration of the first acid solution is 5%, 10%, 15%, 20%, 25%, 30%, or any combination thereof; preferably, the mass concentration of the first acid solution is 8% to 15%.

[0063] In some embodiments of the present invention, step S2, the acid leaching treatment includes pressurized acid leaching of a mixture of leaching residue and a second acid solution.

[0064] In some embodiments of the present invention, in step S2, the acid leaching temperature is 130–175°C, and the acid leaching time is 0.5–6 h; typically, but not limitingly, for example, the acid leaching temperature is a range of 130°C, 140°C, 150°C, 160°C, 170°C, or any combination thereof; and the acid leaching time is a range of 0.5 h, 2 h, 3 h, 4 h, 5 h, 6 h, or any combination thereof.

[0065] In some embodiments of the present invention, in step S2, the pressure of the acid leaching treatment is 0.2 to 0.9 MPa; typically, but not limitingly, for example, the pressure of the acid leaching treatment is a range of 0.2 MPa, 0.4 MPa, 0.6 MPa, 0.8 MPa, 0.9 MPa, or any combination thereof.

[0066] The acid leaching stage employs pressurized acid leaching, which uses pressure conditions higher than atmospheric pressure to achieve efficient leaching of impurities.

[0067] In some embodiments of the present invention, in step S2, the acid leaching treatment includes stirring leaching.

[0068] In some embodiments of the present invention, in step S2, the mass ratio of the second acid solution to the leaching residue is (1 to 5):1; typically, but not limitingly, for example, the mass ratio of the second acid solution to the leaching residue is 1:1, 2:1, 3:1, 4:1, 5:1 or any combination thereof.

[0069] In some embodiments of the present invention, in step S2, the mass concentration of the second acid solution is 13% to 30%; preferably, the mass concentration of the second acid solution is 15% to 25%.

[0070] In some embodiments of the present invention, in step S2, the first acid solution and the second acid solution each independently include at least one of hydrochloric acid, nitric acid, acetic acid, sulfuric acid and hydrofluoric acid; preferably, in step S2, the first acid solution and the second acid solution are hydrochloric acid solutions.

[0071] The mother liquor after acid leaching can be used as a supplementary acid for the next acid leaching, which improves the utilization rate of acid used for acid leaching and effectively reduces the need for subsequent acid reprocessing.

[0072] In some embodiments of the present invention, step S2, after acid leaching, further includes solid-liquid separation, washing, and drying.

[0073] In some embodiments of the present invention, the fine powder content of the boiling chlorination feedstock is ≤5%.

[0074] In some embodiments of the present invention, the TiO2 content in the boiling chlorination feedstock is ≥85 wt.%, the CaO content is ≤0.1 wt.%, and the total content of CaO and MgO is ≤1.5 wt.%; preferably, the TiO2 content in the boiling chlorination feedstock is ≥90 wt.%.

[0075] The method for preparing boiling chlorination feedstock from titanium slag of the present invention has a TiO2 yield of ≥90%; preferably, the TiO2 yield is ≥95%.

[0076] In the embodiments and comparative examples of this invention, the particle size of the water-quenched titanium slag is 20-160 mesh, and it is obtained by water quenching molten titanium slag.

[0077] Example 1

[0078] The method for preparing fluidized bed chlorination feedstock from titanium slag provided in this embodiment includes the following steps:

[0079] S1. Water-quenched titanium slag is pretreated at 150℃ for 4 hours, and the oxygen volume content in the furnace is 15% to obtain pretreated titanium slag. The low-valence titanium content in the pretreated titanium slag is 0.45wt.%.

[0080] S2. A 27 wt.% hydrochloric acid solution and pretreated titanium slag were mixed at a mass ratio of 0.5:1 and subjected to heap leaching at 80°C for 20 min. The leaching residue was obtained after filtration.

[0081] S3. Place the mixture of leaching residue and hydrochloric acid solution in a pressure reactor and heat it to 130°C. Leach under pressure of 0.25 MPa for 6 hours. Adjust the liquid-solid ratio of the mixture to 1 g: 1 g and the concentration of hydrochloric acid solution to 30 wt.%. After leaching, the mixture is subjected to solid-liquid separation, washing and drying to obtain acid leaching residue, which is the boiling chlorination raw material.

[0082] The index analysis of water-quenched titanium slag and acid-leached slag is shown in Table 1.

[0083] Table 1

[0084]

[0085] The TiO2 yield and fine powder content in the acid leaching residue are shown in Table 2.

[0086] Table 2

[0087]

[0088] Example 2

[0089] The method for preparing fluidized bed chlorination feedstock from titanium slag provided in this embodiment includes the following steps:

[0090] S1. Water-quenched titanium slag is pretreated at 300℃ for 2 hours, and the oxygen volume content in the furnace is 10% to obtain pretreated titanium slag. The low-valence titanium content in the pretreated titanium slag is 0.3wt.%.

[0091] S2. A 15 wt.% hydrochloric acid solution and pretreated titanium slag were mixed at a mass ratio of 1:1 and subjected to column leaching at 50°C for 90 min. The leaching residue was obtained after filtration.

[0092] S3. Place the mixture of leaching residue and hydrochloric acid solution in a pressure reactor and heat it to 175°C. Leach under pressure of 0.86 MPa for 0.5 h. Adjust the liquid-solid ratio of the mixture to 2.4 g: 1 g and the concentration of hydrochloric acid solution to 21 wt.%. After leaching, the mixture is subjected to solid-liquid separation, washing and drying to obtain acid leaching residue, which is the boiling chlorination raw material.

[0093] The index analysis of water-quenched titanium slag and acid-leached slag is shown in Table 3.

[0094] Table 3

[0095]

[0096] The TiO2 yield and fine powder content in the acid leaching residue are shown in Table 4.

[0097] Table 4

[0098]

[0099] Example 3

[0100] The method for preparing fluidized bed chlorination feedstock from titanium slag provided in this embodiment includes the following steps:

[0101] S1. Water-quenched titanium slag is pretreated at 350℃ for 1.5h, and the volume content of oxygen in the furnace is 18%, to obtain pretreated titanium slag. The low-valence titanium content in the pretreated titanium slag is 0.23wt.%.

[0102] S2. An 8 wt.% hydrochloric acid solution and pretreated titanium slag are mixed at a mass ratio of 2:1 and leached by stirring at 100°C for 120 min. The leached residue is obtained after filtration.

[0103] S3. Place the mixture of leaching residue and hydrochloric acid solution in a pressure reactor and heat it to 155°C. Leach under pressure of 0.86 MPa for 6 hours. Adjust the liquid-solid ratio of the mixture to 5 g: 1 g and the concentration of hydrochloric acid solution to 17 wt.%. After leaching, the mixture is subjected to solid-liquid separation, washing and drying to obtain acid leaching residue, which is the boiling chlorination raw material.

[0104] The index analysis of water-quenched titanium slag and acid-leached slag is shown in Table 5.

[0105] Table 5

[0106]

[0107] The TiO2 yield and fine powder content in the acid leaching residue are shown in Table 6.

[0108] Table 6

[0109]

[0110] Example 4

[0111] The method for preparing fluidized bed chlorination feedstock from titanium slag provided in this embodiment includes the following steps:

[0112] S1. Water-quenched titanium slag is pretreated at 550℃ for 0.5h, and the volume content of oxygen in the furnace is 20% to obtain pretreated titanium slag. The low-valence titanium content in the pretreated titanium slag is 0.1wt.%.

[0113] S2. A 10 wt.% hydrochloric acid solution and pretreated titanium slag are mixed at a mass ratio of 1.5:1 and leached by stirring at 25°C for 120 min. The leached residue is obtained after filtration.

[0114] S3. Place the mixture of leaching residue and hydrochloric acid solution in a pressure reactor and heat it to 160°C. Leach under pressure of 0.6 MPa for 3 hours. Adjust the liquid-solid ratio of the mixture to 4 g: 1 g and the concentration of hydrochloric acid solution to 15 wt.%. After leaching, the acid leaching residue is obtained by solid-liquid separation, washing and drying, which is the boiling chlorination raw material.

[0115] The index analysis of water-quenched titanium slag and acid-leached slag is shown in Table 7.

[0116] Table 7

[0117]

[0118] The TiO2 yield and fine powder content in the acid leaching residue are shown in Table 8.

[0119] Table 8

[0120]

[0121] Comparative Example 1

[0122] The method for preparing fluidized bed chlorination feedstock from titanium slag provided in this comparative example includes the following steps:

[0123] The mixture of water-quenched titanium slag and hydrochloric acid solution from Example 4 was placed in a pressure reactor and heated to 160°C. It was then pressure-leached at 0.6 MPa for 3 hours. The liquid-solid ratio of the mixture was adjusted to 4 g: 1 g, and the concentration of the hydrochloric acid solution was 15 wt.%. After leaching, the mixture was subjected to solid-liquid separation, washing, and drying to obtain acid leaching residue, which is the boiling chlorination raw material.

[0124] The index analysis of water-quenched titanium slag and acid-leached slag is shown in Table 9.

[0125] Table 9

[0126]

[0127]

[0128] The TiO2 yield and fine powder content in the acid leaching residue are shown in Table 10.

[0129] Table 10

[0130]

[0131] Comparative Example 2

[0132] The method for preparing boiling chlorination feedstock from titanium slag provided in this comparative example is the same as that in Example 4, except that the pretreatment temperature in step S1 is 800°C.

[0133] The index analysis of water-quenched titanium slag and acid-leached slag is shown in Table 11.

[0134] Table 11

[0135]

[0136] The TiO2 yield and fine powder content in the acid leaching residue are shown in Table 12.

[0137] Table 12

[0138]

[0139]

[0140] Experimental Example 1

[0141] XRD analysis of the phase structure of water-quenched titanium slag after pretreatment at different temperatures clearly shows the structural changes of the water-quenched titanium slag at different temperatures. The results are as follows: Figure 1 As shown.

[0142] The water-quenched titanium slag is the same as in Example 4, with a pretreatment time of 1 hour and an oxygen volume content of 10% in the furnace.

[0143] from Figure 1It can be seen that after the water-quenched slag undergoes heat pretreatment, the diffraction peak intensity at 2Theta (18°, 25.3°, 32.5°) gradually weakens, while the peak intensity at 2Theta (27.5°, 36.1°, 41.2°, 54.3°, and 56.6°) gradually strengthens, indicating that the phase structure of the water-quenched slag undergoes significant changes during the heat pretreatment process.

[0144] Using the water-quenched titanium slag from Example 4 as raw material, the relationship between different pretreatment temperatures and the TiO2 yield and impurity content in the acid-leached slag after acid leaching was investigated. The results are as follows: Figure 2 As shown.

[0145] The method for preparing acid leaching residue using water-quenched titanium slag as raw material includes the following steps: S1, pre-treating the water-quenched titanium slag from Example 4 at different temperatures for 2 hours, with an oxygen volume content of 15% in the furnace, to obtain pre-treated titanium slag; S2, mixing the pre-treated titanium slag with a 20wt.% hydrochloric acid solution, with a liquid-to-solid ratio of 1g:1g, and leaching at 100℃ for 60 minutes using a stirring method, followed by filtration to obtain leaching residue; S3, placing the leaching residue and hydrochloric acid solution mixture in a pressure reactor and heating it to 150℃, leaching under pressure at 0.45MPa for 4 hours, adjusting the liquid-to-solid ratio of the mixture to 2.5g:1g, and the concentration of the hydrochloric acid solution to 22wt.%, and after leaching, sequentially performing solid-liquid separation, washing, and drying to obtain acid leaching residue.

[0146] from Figure 2 It can be seen that the higher the pretreatment temperature, the higher the TiO2 yield. The leaching rates of CaO and MgO are almost unaffected by the pretreatment temperature when it is below 550℃. However, when the pretreatment temperature is above 550℃, the leaching rates of CaO and MgO decrease with increasing pretreatment temperature, which is reflected in the increased CaO and MgO content in the leaching residue. Increasing the pretreatment temperature makes the leaching residue unable to meet the requirements of fluidized bed chlorination feedstock. The preparation method of this invention has the advantages of high TiO2 yield, high leaching rate of impurities such as CaO and MgO, and low content of impurities such as CaO and MgO in the acid leaching residue. Figure 2 The advantages of this invention will be further described by taking the effect of different temperature pretreatment on the CaO and MgO content and TiO2 yield in the acid leaching residue as an example. The relationship between pretreatment temperature and the content of other impurities and TiO2 yield in the acid leaching residue will not be elaborated here.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for the production of fluidized chlorination feedstock from titanium slag, characterized in that, The method comprises the following steps: S1, pretreating water-quenched titanium slag at 150-550℃, the pretreatment comprising oxidative roasting, the pretreatment time being 0.5-4h, to obtain pretreated titanium slag; in the water-quenched titanium slag, the content of TiO2 is 70-85 wt.%, the content of CaO is ≥0.2 wt.%, and the content of MgO is ≥2 wt.%; the content of low-valence titanium in the pretreated titanium slag is ≤0.5 wt.%; S2, sequentially performing pre-leaching treatment and acid leaching treatment on the pretreated titanium slag to obtain boiling chlorination raw material.

2. The method of producing a fluidized chlorination feedstock from titanium slag according to claim 1, characterized in that, The particle size of the water-quenched titanium slag is 20-160 mesh.

3. The method of claim 1, wherein the titanium slag is prepared by the steps of: In step S2, the pre-leaching treatment comprises acid leaching a mixture of pretreated titanium slag and first acid solution to obtain leached residue. ​ 4. The process for the preparation of fluid chlorination feedstock from titanium slag as claimed in claim 3 wherein, The pre-leaching treatment temperature is 20-100℃, and the pre-leaching treatment time is 20-120min.

5. The method of claim 3, wherein the titanium slag is prepared by the steps of: preparing a titanium slag by a conventional method; and adding a flux to the titanium slag to form a fluxed titanium slag. In step S2, the mass ratio of the first acid solution to the pretreated titanium slag is (0.5-2):

1.

6. The method of producing a fluidized chlorination feedstock from titanium slag according to claim 3, characterized in that, The mass concentration of the first acid solution is 5%-30%.

7. The method of producing a fluidized chlorination feedstock from titanium slag according to claim 3, characterized in that, In step S2, the acid leaching treatment comprises pressure acid leaching a mixture of the leached residue and second acid solution.

8. The process for the preparation of fluid chlorination feedstock from titanium slag as claimed in claim 7 wherein, In step S2, the acid leaching treatment temperature is 130-175℃, and the acid leaching treatment time is 0.5-6h.

9. The method of claim 7, wherein the titanium slag is prepared by the steps of: preparing a titanium slag by a conventional method; and adding a flux to the titanium slag to form a fluxed titanium slag. The acid leaching treatment pressure is 0.2-0.9MPa.

10. The method of claim 7, wherein the titanium slag is prepared by the steps of: preparing a titanium slag by a conventional method; and adding a flux to the titanium slag to form a fluxed titanium slag. In step S2, the mass ratio of the second acid solution to the leached residue is (1-5):

1.

11. The method of claim 7, wherein the titanium slag is prepared by the steps of: preparing a titanium slag by a conventional method; and adding a flux to the titanium slag to form a fluxed titanium slag. The mass concentration of the second acid solution is 13%-30%.

12. A process for the production of fluid chlorination feedstock from titanium slag according to claim 10 or 11, characterised in that, In step S2, the first acid solution and the second acid solution each independently comprise at least one of hydrochloric acid, nitric acid, acetic acid, sulfuric acid and hydrofluoric acid.

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