Acid hydrolysis method in the industrial production process of high-phosphorus titanium concentrate using hydrochloric acid method titanium dioxide

Abstract

The invention discloses an acidolysis method in an industrial production process of hydrochloric acid titanium dioxide of high-phosphorus titanium concentrate, which can ensure the industrial production of the hydrochloric acid titanium dioxide acidolysis process system, and can significantly improve the acidolysis rate of titanium concentrate and the concentration of titanium liquid compared with other titanium dioxide production methods. The whole acidolysis process does not produce low-concentration titanium liquid, reduces the amount of hydrochloric acid used, improves the efficiency of reducing iron powder and the stability of the acidolysis titanium liquid, has obvious dephosphorization effect, and is conducive to the preparation of high-quality pigment titanium dioxide.

Description

Technical Field

[0001] The invention relates to the technical field of titanium dioxide and titanium dioxide production, and in particular to an acidolysis method in the industrial production process of titanium dioxide using a hydrochloric acid method with high-phosphorus titanium concentrate. Background Art

[0002] Titanium dioxide is the best white pigment in the world. It is widely used in coatings, plastics, papermaking, rubber, ink, chemical fiber, electronics, ceramics and other industrial fields. It is one of the most important inorganic chemical products, and its sales value ranks third in the world. Therefore, the per capita consumption of titanium dioxide can relatively measure the living standards and industrial level of a country.

[0003] At present, the mature processes for industrial production of titanium dioxide in the world are sulfuric acid method and chlorination method. The production of titanium dioxide by sulfuric acid method is to use sulfuric acid to acidify titanium concentrate or titanium slag to produce titanium sulfate solution, and then reduce trivalent iron with iron powder, remove divalent iron by freezing crystallization, hydrolysis, filtration and washing, bleaching reduction, salt treatment, drying, calcination and post-treatment to obtain titanium dioxide by sulfuric acid method. The advantages are that the ore source is easy to obtain and the process technology is relatively mature. The disadvantages are that the process route is long, the consumption of sulfuric acid and water is high, the amount of by-product ferrous sulfate is large and difficult to fully utilize, the waste acid and wastewater treatment is difficult, the environmental pollution is large, and the comprehensive cost is relatively high at this stage. The production of titanium dioxide in my country is mainly based on sulfuric acid method. Chlorination method titanium dioxide production: Use chlorine and petroleum coke to prepare titanium tetrachloride through boiling chlorination or molten salt chlorination of rutile ore or high titanium slag, and then obtain titanium tetrachloride by refining, gas phase oxidation and post-treatment. Advantages: short process and high product quality. Disadvantages: Raw materials are controlled, high-temperature chlorination and high-temperature oxidation have high requirements on the process manufacturing of the equipment itself, the equipment structure is complex, and the investment is large. Since chlorine is used as the main raw material, the safety risk of production is high. The amount of slag washing wastewater and waste acid is large and difficult to handle. Developed countries abroad mainly produce titanium dioxide by the chloride process. At present, only a few companies in my country's chloride process titanium dioxide industry, such as Longmang Billions and CITIC Titanium, can produce a small amount.

[0004] After decades of exploration, some research results have been achieved in the production process of titanium dioxide by hydrochloric acid, but it has not actually reached the requirements of industrialization. The production of titanium dioxide by hydrochloric acid is to use hydrochloric acid to hydrolyze titanium concentrate or titanium slag to produce titanium liquid. The subsequent process is divided into two routes: one is to obtain titanium dioxide by hydrochloric acid through iron powder reduction to remove trivalent iron, concentration, freezing crystallization to remove ferrous chloride, hydrolysis, filtration and washing, drying, calcination and post-treatment; the other is to extract and separate Ti 4+ and Fe 2+ , Fe 3+ , Ca 2+ Mg 2+The refined titanium liquid is treated by hydrolysis (or spray heating hydrolysis), filtration, washing, drying, calcination and post-treatment to obtain hydrochloric acid titanium dioxide. The two main preparation processes of hydrochloric acid titanium dioxide in the world: the US ANI method (the main patent is US6440383) and the Canadian CTL method (the main patent is CA2513309), with the extraction of titanium element as the goal. There are also some literature reports that the effective separation of titanium element is achieved by extracting various metal elements. However, the current hydrochloric acid titanium dioxide production process is not mature, the titanium concentrate acid hydrolysis rate and titanium liquid concentration are not high, the titanium liquid stability is low, the extraction efficiency is low, the extraction agent separation effect is poor, it is difficult to produce pigment titanium dioxide, the recycling of hydrochloric acid is not thorough, the solid waste cannot be comprehensively utilized, and the environmental protection problem has not been completely solved. At present, only Fujian Kuncai Materials Technology Co., Ltd. has been reported to use hydrochloric acid extraction process to produce pearlite pigments of titanium dioxide. Summary of the invention

[0005] The main technical problem solved by the present invention is to provide an acidolysis method in the industrial production process of hydrochloric acid method titanium dioxide of high-phosphorus titanium concentrate, which can ensure the industrial production of the hydrochloric acid method titanium dioxide acidolysis process system. Compared with other titanium dioxide production methods, it can significantly improve the acidolysis rate of titanium concentrate and the concentration of titanium liquid. The entire acidolysis process does not produce low-concentration titanium liquid, reduces the amount of hydrochloric acid used, improves the efficiency of reducing iron powder and the stability of the acidolysis titanium liquid, has obvious dephosphorization effect, and is conducive to the preparation of high-quality pigment titanium dioxide.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: an acid hydrolysis method in the industrial production process of high-phosphorus titanium concentrate hydrochloric acid titanium dioxide, comprising: (1) acid leaching titanium concentrate raw material is pre-activated and ground titanium concentrate powder; (2) regenerating acid washing the filter cake formed by acid leaching and filtration to prepare acid hydrolysis acid, and Ti in the filter cake is 4+ All of them are transferred to the acid solution; then the pre-activated powdered titanium concentrate is added, stirred and mixed, and initially acid-lyzed to further increase the Ti 4+ concentration; (3) Ti already exists in the mixing stage at room temperature 4+ Add iron powder, Ti 4+ Reduction to Ti 3+ , so that Ti always exists during the acid hydrolysis process 3+ , Fe 3+ Immediately reduced to Fe by iron powder 2+, realizing the reduction of the acidolysis system; (4) introducing hydrogen chloride gas, using the heat of solution of hydrogen chloride gas to heat the system to 88-95°C, and maintaining the acidolysis temperature of the system to increase the acidity of the system, stirring the reaction, and maintaining the free hydrochloric acid concentration in the acidolysis kettle>270g / L, (5) 0.4-0.6 hours before the termination of the acidolysis reaction, adding the phosphorus removal flocculant composite to the 88-95°C acidolysis slurry, and performing high-temperature electrical neutralization-adsorption bridging dephosphorization reaction to flocculate phosphorus-containing polymer colloid, titanium dioxide colloid and orthosilicic acid colloid; when the temperature drops to 83-86°C, the material is directly hot filtered after discharge, and the acidolysis liquid is obtained by solid-liquid separation, and the filter cake is washed with regenerated acid produced by the chloride salt roasting system to prepare the acidolysis acid.

[0007] According to the mineral mosaic characteristics of titanium concentrate raw materials, the titanium concentrate fine materials activated and ground by vertical mill and stirred mill are put into the acid hydrolysis system. The activated titanium concentrate has the characteristics of good separation of each component and high surface energy of powder, which is easy to acid hydrolyze. The particle size is controlled to D max <38μm (400 mesh).

[0008] The regenerated acid produced by the chloride salt roasting system is used to wash the filter cake formed by acid hydrolysis filtration to prepare acid hydrolysis acid. 4+ All are transferred to acid deacidification. Compared with the known process, no low-concentration titanium liquid (commonly known as low-concentration water in the industry) is produced in the entire production process;

[0009] Acid hydrolysis acid (concentration 28-30wt%) is added to the acid hydrolysis kettle according to a certain ore-acid ratio (mass-volume ratio), and then activated titanium concentrate is added and the ore is mixed at room temperature.

[0010] In addition to this patent application, other patents, literature reports and production processes for the preparation of titanium dioxide by hydrochloric acid method and sulfuric acid method are to add iron powder to reduce Fe after the acid hydrolysis reaction. 3+ Fe 2+ , the main reaction process is: 2Fe 3+ +Fe→2Fe 2+ , partially Ti 4+ +Fe→Ti 3+ +Fe 2+ To ensure that the Fe 3+ All reduced to Fe 2+ Since the acidity is low after the acid hydrolysis, the stability of the titanium liquid is reduced. In the reduction process of these existing process steps, the iron powder is easily coated by the metatitanic acid colloid produced by early hydrolysis, resulting in a slow and incomplete reduction rate, a high iron powder dosage, and poor stability of the titanium liquid. 4+ Add iron powder, Ti 4+ Reduction to Ti 3+ To maintain the presence of Ti during the acid hydrolysis process 3+, realizing the reduction acid hydrolysis system, the Fe 3+ Immediately reduced to Fe 2+ The innovation of acid hydrolysis as a reduction system is reflected in the following main reaction process: Ti 4+ +Fe→Ti 3+ +Fe 2+ , Fe 3+ +Ti 3+ →Fe 2+ +Ti 4+ According to the principle of simultaneous equilibrium, it is beneficial to the acid hydrolysis reaction of FeO·TiO2+6HCl+2H2O→FeCl2+TiCl4·5H2O and Fe2O3+6HCl→2FeCl3+3H2O, improving the acid hydrolysis rate and acid hydrolysis rate, ensuring Fe 3+ Complete reduction of iron powder can improve the utilization rate of iron powder and avoid the generation of Fe in the hydrochloric acid system. 3+ It forms a colloid with phosphorus and titanium that affects the filtration performance and stability of titanium liquid, avoids early hydrolysis of titanium liquid, and improves the stability of titanium liquid.

[0011] Introduce hydrogen chloride gas generated by hydrochloric acid analysis or chloride salt roasting system, use the dissolution heat of hydrogen chloride gas to heat the system to 88-95℃, and maintain the acidolysis temperature of the system to increase the acidity of the system, and stir the reaction for 1.5 hours. During the reaction, maintain the free hydrochloric acid concentration in the acidolysis kettle>270g / L, which helps the acidolysis slurry to be directly hot filtered without sedimentation.

[0012] 0.4-0.6 hours before the termination of the acidolysis reaction, add the phosphorus removal flocculant composite to the 88-95℃ acidolysis slurry to realize the electrical neutralization-adsorption bridging dephosphorization reaction under high temperature, so as to achieve the purpose of flocculating phosphorus-containing polymer colloid, titanium dioxide colloid and orthosilicic acid colloid. When the temperature drops to 83-86℃, the material is directly hot filtered after discharge, and the acidolysis liquid is obtained by solid-liquid separation. The filter cake is washed with regenerated acid produced by a chloride salt roasting system to prepare acidolysis acid. The phosphorus removal flocculant composite is a composite of ultra-high molecular weight cationic polyacrylamide and inorganic-organic composite phosphorus removal agent. Calculated by mass, the phosphorus removal flocculant composite includes: 20-80 parts of cationic polyacrylamide and 20-80 parts of special inorganic-organic composite phosphorus removal agent. The amount of phosphorus removal flocculant composite in the acidolysis liquid is 80-100g / m 3 The inorganic-organic composite phosphorus removal agent is composed of polyferric sulfate, PDMDAAC homopolymer and copolymer, and chitin.

[0013] The beneficial effects of the present invention are:

[0014] Titanium concentrate acid hydrolysis rate>95%;

[0015] The concentration of titanium liquid can be as high as Ti 4+ : 200g / L;

[0016] Titanium liquid stability>500;

[0017] Acid slurry is deeply dephosphorized, and the P content in the titanium liquid is less than 30ppm, which is a high-quality titanium liquid for subsequent seed hydrolysis to produce high-grade rutile titanium dioxide pigment precursor;

[0018] The acid-solution slurry is deeply dephosphorized, which ensures that the P content of the subsequent frozen crystallized FeCl2·4H2O is less than 10ppm, and high-quality iron oxide powder can be produced through the chloride salt roasting system;

[0019] Due to the use of Ti 4+ The hydrochloric acid solution is used as the acid solution, and no low-concentration titanium liquid (commonly known as low-concentration water in the industry) is produced in the entire production process;

[0020] The introduction of hydrogen chloride gas produced by hydrochloric acid analysis or chloride salt roasting system reduces the H + The concentration requirement is to maintain the free hydrochloric acid concentration in the acid hydrolysis pot > 270g / L, which is conducive to direct hot filtration of the acid hydrolysis slurry without sedimentation;

[0021] The present invention lays a foundation for the industrialized production of titanium dioxide by the hydrochloric acid method, and the production line is being constructed. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present invention are described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0023] The embodiments of the present invention include:

[0024] The invention discloses an acid hydrolysis method for the industrial production process of titanium dioxide powder produced by the hydrochloric acid method using high-phosphorus titanium concentrate, which aims to solve the problems in the existing hydrochloric acid method titanium dioxide production process, such as low titanium concentrate acid hydrolysis rate and low titanium liquid concentration, high iron powder dosage and acid consumption, low titanium liquid stability, and poor titanium liquid quality, which make it difficult to produce pigment titanium dioxide. The method is implemented by using pre-activated ground titanium concentrate slurry, adding iron powder at the beginning of the acid hydrolysis reaction, and adding a phosphorus removal flocculant before the acid hydrolysis reaction is terminated to remove titanium phosphate colloid, titanium dioxide colloid, and orthosilicic acid colloid suspension.

[0025] Example 1

[0026] The titanium concentrate in this embodiment is Panzhihua titanium concentrate, with a TiO2 content of 46.1%, a FeO content of 36.0%, a Fe2O3 content of 5.15%, a P content of 0.047%, and a D max ≤150μm (100 mesh). The titanium concentrate powder is pre-activated and ground with a vertical mill, and the particle size of the obtained acid-hydrolyzed titanium concentrate fine material is D 98 <36μm, Dmax <38μm (400 mesh).

[0027] 700L of acid was dissolved (HCl: 320.34g / L, Ti 4+ (in terms of TiO2): 27.52 g / L, Fe 2+ :16.98g / L) added to a closed volume of 1m 3 Add 280kg of titanium concentrate fine material into the acid hydrolysis reactor and start stirring. The ore-acid ratio (mass-to-volume ratio) is 1:2.5.

[0028] Add 8kg iron powder (elemental iron content 95%) to make Fe 3+ Reduction to Fe 2+ , to ensure that Ti in the acid solution slurry is 3+ Reach 1.5~2g / L.

[0029] The hydrogen chloride gas obtained by hydrochloric acid analysis is introduced, and the system is heated to 90°C by the heat of solution of the hydrogen chloride gas. The system temperature is maintained to increase the acidity of the system, and the acid is stirred for 1.5 hours. The acid hydrolysis tail gas generated during the acid hydrolysis process is condensed and absorbed by the hydrochloric acid generated by the hydrochloric acid analysis system.

[0030] Add 130g of phosphorus removal flocculation composite agent (pre-dissolved, components: ultra-high molecular weight cationic polyacrylamide accounts for 40wt%, inorganic-organic composite phosphorus removal agent accounts for 60wt%), continue stirring for 0.5 hours, and maintain the free hydrochloric acid concentration of the acid hydrolysis reactor at more than 270g / L.

[0031] The tail gas system is used to extract condensable gases to reduce the effective acid concentration of the titanium liquid. When the temperature reaches 85°C, the material is discharged and hot filtered.

[0032] Titanium liquid cleaning (acid solution slurry hot filtration and then frozen crystallization for ferrous separation) results: Ti in titanium liquid 4+ :203.46g / L,Ti 3+ : 1.25g / L, P: 25.53ppm; Acid hydrolysis rate of titanium concentrate: 97.39%, deep phosphorus removal of titanium liquid, clear titanium liquid is purple, stability>500.

[0033] Example 2

[0034] The titanium concentrate in this embodiment is Panzhihua titanium concentrate, with a TiO2 content of 45.84%, a FeO content of 34.57%, a Fe2O3 content of 5.25%, a P content of 0.079%, and a D max ≤74μm (200 mesh). The titanium concentrate powder is pre-activated and ground with a vertical mill, and the particle size of the obtained acid-hydrolyzed titanium concentrate fine material is D 98 <35.3μm, D max<37μm (400 mesh).

[0035] 700L of acid was dissolved (HCl: 320.34g / L, Ti 4+ (in terms of TiO2): 27.52 g / L, Fe 2+ :16.98g / L) added to a closed volume of 1m 3 Add 350kg of titanium concentrate fine material into the acid hydrolysis reactor and start stirring. The ore-acid ratio (mass-to-volume ratio) is 1:2.0.

[0036] Add 9.96 kg of iron powder (95% iron content) to make Fe 3+ Reduction to Fe 2+ , to ensure that Ti in the acid solution slurry is 3+ Reach 1.5~2g / L.

[0037] The hydrogen chloride gas obtained by hydrochloric acid analysis is introduced, and the system is heated to 90°C by the heat of solution of the hydrogen chloride gas. The system temperature is maintained to increase the acidity of the system, and the acid is stirred for 1.5 hours. The acid hydrolysis tail gas generated during the acid hydrolysis process is condensed and absorbed by the hydrochloric acid generated by the hydrochloric acid analysis system.

[0038] Add 163g of phosphorus removal flocculation composite agent (pre-dissolved, components: ultra-high molecular weight cationic polyacrylamide accounts for 60wt%, inorganic-organic composite phosphorus removal agent accounts for 40wt%), continue stirring for 0.5 hours, and maintain the free hydrochloric acid concentration of the acid hydrolysis reactor at more than 270g / L.

[0039] The tail gas system is used to extract condensable gases to reduce the effective acid concentration of the titanium liquid. When the temperature reaches 85°C, the material is discharged and hot filtered.

[0040] Titanium liquid cleaning (acid solution slurry hot filtration and then frozen crystallization for ferrous separation) results: Ti in titanium liquid 4+ :253.17g / L,Ti 3+ : 1.36g / L, P: 38.14ppm; Acid hydrolysis rate of titanium concentrate: 96.84%, deep phosphorus removal of titanium liquid, clear titanium liquid is purple, stability>500.

[0041] Example 3

[0042] In this embodiment, the raw material is Panzhihua titanium medium ore, whose TiO2 content in the beneficiation process does not meet the grade requirements of titanium concentrate, with a TiO2 content of 37.51%, a FeO content of 38.57%, a Fe2O3 content of 7.20%, a P content of 0.051%, and a Dmax of ≤74 μm (200 mesh). The titanium concentrate powder is pre-activated and ground with a vertical mill, and the particle size of the obtained acid-hydrolyzed titanium concentrate fine material is D 98<35.3μm, Dmax<37μm (400 mesh).

[0043] 700L of acid was dissolved (HCl: 320.34g / L, Ti 4+ (in terms of TiO2): 27.52 g / L, Fe 2+ :16.98g / L) added to a closed volume of 1m 3 Add 350kg of titanium concentrate fine material into the acid hydrolysis reactor and start stirring. The ore-acid ratio (mass-to-volume ratio) is 1:2.0.

[0044] Add 13.79 kg of iron powder (95% iron content) to make Fe 3+ Reduction to Fe 2+ , to ensure that Ti in the acid solution slurry is 3+ Reach 1.5~2g / L.

[0045] The hydrogen chloride gas obtained by hydrochloric acid analysis is introduced, and the system is heated to 90°C by the heat of solution of the hydrogen chloride gas. The system temperature is maintained to increase the acidity of the system, and the acid is stirred for 1.5 hours. The acid hydrolysis tail gas generated during the acid hydrolysis process is condensed and absorbed by the hydrochloric acid generated by the hydrochloric acid analysis system.

[0046] Add 163g of phosphorus removal flocculation composite agent (pre-dissolved, components: ultra-high molecular weight cationic polyacrylamide accounts for 60wt%, inorganic-organic composite phosphorus removal agent accounts for 40wt%), continue stirring for 0.5 hours, and maintain the free hydrochloric acid concentration of the acid hydrolysis reactor at more than 270g / L.

[0047] The tail gas system is used to extract condensable gases to reduce the effective acid concentration of the titanium liquid. When the temperature reaches 85°C, the material is discharged and hot filtered.

[0048] Titanium liquid cleaning (acid solution slurry hot filtration and then frozen crystallization for ferrous separation) results: Ti in titanium liquid 4+ :236.59g / L,Ti 3+ : 1.04g / L, P: 29.27ppm; Acid hydrolysis rate of titanium concentrate: 95.37%, deep phosphorus removal of titanium liquid, clear titanium liquid is purple, stability>500.

[0049] The titanium concentrate raw materials purchased in Example 1 and Example 2 are both high-phosphorus titanium concentrates, with different P contents, different raw material particle sizes, and slightly different chemical compositions. The titanium concentrate in Example 1 is 10 ore, D max ≤150μm (100 mesh), P content is 0.047%; in Example 2, the titanium concentrate is 20 ore, D max ≤74μm (200 mesh), P content is 0.079%.

[0050] The mineral acid ratios used in Example 1 and Example 2 are different. The mineral acid ratio used in Example 1 is 1:2.5, and the mineral acid ratio used in Example 2 is 1:2.0.

[0051] The dosage and compound composition of the phosphorus removal flocculation compound used in Example 1 and Example 2 are different. Example 1 uses 130g (ultra-high molecular weight cationic polyacrylamide accounts for 40wt%, and the inorganic-organic composite phosphorus removal agent accounts for 60wt%), and Example 2 uses 163g of the phosphorus removal flocculation compound (ultra-high molecular weight cationic polyacrylamide accounts for 60wt%, and the inorganic-organic composite phosphorus removal agent accounts for 40wt%).

[0052] It can expand the sources of titanium-containing ore resources and realize the hydrochloric acid method titanium dioxide production of low-grade titanium concentrate.

[0053] The titanium raw material used in Example 2 is Panzhihua high-phosphorus titanium concentrate, while the titanium raw material used in Example 3 is Panzhihua titanium middling ore whose TiO2 content in the beneficiation process does not meet the titanium concentrate grade requirements. The corresponding iron powder dosage is 13.79 kg, and other conditions are the same.

[0054] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent process changes made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An acid hydrolysis method in the industrial production process of high-phosphorus titanium concentrate titanium dioxide by hydrochloric acid method, comprising: (1) The raw material for acid leaching titanium concentrate is titanium concentrate powder that has been pre-activated and ground; The particle size is controlled to be Dmax<38μm; (2) The filter cake is washed with the regenerated acid produced by the chloride salt roasting system, and the filter cake formed by the regenerated acid washing and acid leaching is prepared with an acid hydrolysis concentration of 28 to 30 wt%. The Ti in the filter cake 4+ Transfer all of them into acid deacidification; then add the pre-activated powdered titanium concentrate fine material, the mineral acid mass volume ratio is 1:2-1:3, stir and mix at room temperature to further increase the Ti 4+ concentration; (3) Ti already exists in the mixing stage at room temperature 4+ Add iron powder, Ti 4+ Reduction to Ti 3+ , so that Ti always exists during the acid hydrolysis process 3+ , Fe 3+ Immediately reduced to Fe by iron powder 2+ , realize the reduction acid hydrolysis system; ensure that the Ti in the acid hydrolysis slurry is 3+ (4) introducing hydrogen chloride gas, using the heat of solution of hydrogen chloride gas to heat the system to 88-95°C, maintaining the acidolysis temperature of the system, increasing the acidity of the system, stirring the reaction, and maintaining the free hydrochloric acid concentration in the acidolysis kettle>270g / L; (5) 0.4-0.6 hours before the termination of the acidolysis reaction, adding the phosphorus removal flocculant composite to the 88-95°C acidolysis slurry to carry out high-temperature electrical neutralization-adsorption bridging dephosphorization reaction, flocculating phosphorus-containing polymer colloid, titanium dioxide colloid and orthosilicic acid colloid; when the temperature drops to 83-86°C, directly hot filtration is carried out after the material is discharged, and solid-liquid separation is carried out to obtain an acidolysis solution, and the filter cake is washed with regenerated acid produced by a chloride salt roasting system to prepare an acidolysis acid; No low-concentration titanium liquid is produced in the whole process; the phosphorus removal flocculant compound is a compound of ultra-high molecular weight cationic polyacrylamide and inorganic-organic composite phosphorus removal agent, and the inorganic-organic composite phosphorus removal agent is a compound of polymerized ferric sulfate, PDMDAAC homopolymer and copolymer, and chitin; calculated by weight, the phosphorus removal flocculant compound includes: 20 to 80 parts of cationic polyacrylamide and 20 to 80 parts of inorganic-organic composite phosphorus removal agent.

2. The acid hydrolysis method according to claim 1, wherein the amount of the phosphorus removal flocculation composite agent is 80-100 g / m 3 .

3. The acidolysis method according to claim 1, wherein the hydrogen chloride gas in step (4) is produced by hydrochloric acid analysis or a chloride salt roasting system.

4. The acid hydrolysis method according to claim 1, wherein the stirring reaction in step (4) is performed for 1.5 hours.

5. The acidolysis method as claimed in claim 1, wherein the phosphorus removal flocculation composite agent is added 0.5 hours before the termination of the acidolysis reaction in step (5).

6. The acid hydrolysis method as claimed in claim 1, wherein after the reaction in step (5), the condensable gas is sucked out by the tail gas system to reduce the effective acid concentration of the titanium liquid, and when the temperature reaches 85°C, the material is discharged and hot filtered.