Method for preparing titanium-rich material and battery-grade iron phosphate from ilmenite

Abstract

The application discloses a method for preparing a titanium-rich material and battery-grade iron phosphate from ilmenite, which comprises the following steps: (1) adding a binder and appropriate water to ilmenite powder, uniformly mixing the mixture, and then balling the mixture to obtain ilmenite pellets; the ilmenite pellets are dried and subjected to oxidation treatment; (2) placing the oxidized pellets in hydrogen for reduction treatment; (3) crushing and screening the reduced ilmenite pellets to obtain reduced ilmenite powder; the reduced ilmenite powder is added to water together with a rusting agent, and oxygen is introduced to obtain rusted ilmenite; (4) separating the rusted ilmenite to obtain a titanium-rich material and ilmenite slag; (5) adding a mixed acid solution of sulfuric acid and phosphoric acid to the ilmenite slag, and then performing heating and stirring reaction; the ilmenite slag is filtered to obtain leaching filtrate and a titanium-rich filter residue; (6) adjusting the pH of the filtrate and performing heating and stirring reaction at a set temperature; the filtrate is aged and filtered to obtain crude iron phosphate; and (7) calcining the crude iron phosphate, and then cooling the calcined product to obtain battery-grade iron phosphate.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of comprehensive recycling of solid waste, and relates to a method for preparing a titanium-rich material and a battery-grade iron phosphate from ilmenite. BACKGROUND

[0002] Titanium is widely distributed in the earth's crust, with an abundance of 0.61% in the earth's crust. Elemental titanium has high activity and is often combined with oxygen to form various titanium-containing oxides, which usually exist in the form of TiO2 or titanate in minerals. According to statistics, there are more than 140 minerals with a titanium content of more than 1%, among which the main minerals with industrial development and utilization value are rutile and ilmenite. Natural rutile is very scarce, accounting for about 10% of the global titanium resource reserves, and cannot meet the development needs of the titanium industry. More is to rely on ilmenite to provide stable and high-quality raw materials for the titanium industry, with a basic reserve of nearly 1.4 billion tons (calculated based on TiO2 content) on earth. At present, the main raw material used for producing titanium-rich material in industry is ilmenite, and there are mainly three methods: electric furnace melting separation method, reduction corrosion method and acid leaching method. Among them, the reduction corrosion method has become the mainstream production process for preparing artificial rutile from ilmenite, because it has the advantages of less power consumption and chemical reagent consumption, lower production cost, and nearly neutral wastewater discharged during the corrosion process.

[0003] Iron phosphate is mainly used as a precursor for lithium iron phosphate positive electrode materials and in the field of catalysts. According to the classification of raw materials, there are mainly: iron trichloride or ferric nitrate solution reacts with phosphoric acid, hydrogen chloride or nitric acid is decomposed and volatilized at high temperature, and ammonia water is used to neutralize the excess acid to obtain iron phosphate; ferrous sulfate is acidified with phosphoric acid and then reacts with sodium chlorate or hydrogen peroxide to generate ferrous phosphate, and then sodium hydroxide or ammonia water is used to adjust the pH value to about 2 to generate iron phosphate; in addition, there is a method of directly reacting phosphate with ferrous sulfate to generate iron phosphate under the condition of a pH value less than 2. According to the classification of synthesis methods, there are mainly: precipitation method, hydrothermal method, sol-gel method, air oxidation method, controlled crystallization method, etc.

[0004] The raw material for preparing iron phosphate at present is usually a high-purity iron source or a phosphorus source, for example, a Chinese patent document with publication number CN116022757A discloses a preparation method of battery-grade hydrated iron phosphate, the pH value of a ferrous sulfate solution is adjusted to <2, calcium dihydrogen phosphate is added and the total phosphorus concentration in the ferrous sulfate solution is maintained <1 mol / L, a precipitation reaction is carried out at a temperature of 50-90 DEG C for 1.0-3.0 h, liquid-solid separation is carried out, and calcium sulfate residue and ferrous phosphate solution are obtained; the ferrous phosphate solution is subjected to pH value and iron / phosphorus ratio adjustment, hydrogen peroxide is added for oxidation reaction, and then solid-liquid separation and washing are carried out, and battery-grade hydrated iron phosphate is obtained.

[0005] A preparation method of iron phosphate is disclosed in a granted patent with number CN106450547A, a mixed solution of a phosphorus source and an oxidizing agent is mixed with a solution containing Fe 2+ in a parallel flow, a pH adjuster is used to adjust the pH of the precipitation slurry to 1.7-1.8, and a flower-shaped cluster structure iron phosphate is synthesized. The above inventions all use reagent pure iron material as the iron raw material, the raw material is limited, the process flow is long, and the obtained iron phosphate product index is general. In the above preparation methods of iron phosphate, the high-value recycling of the iron-rich titanium slag is not well realized, the process steps are complicated, the process steps are long, the reagent consumption is large, it is not green and environmentally friendly, and the iron phosphate product index is general.

[0006] Therefore, it is necessary to provide a full-process high-value utilization method of ilmenite, so as to realize efficient separation of titanium and iron, clean production, and high-value utilization of iron-rich titanium slag. SUMMARY

[0007] In view of the problems that in the process of obtaining a traditional iron-rich titanium product, titanium and iron are not completely separated, carbon dioxide, smoke dust and waste gas pollute the production process, and the high-value utilization of the iron-rich titanium slag cannot be realized, the purpose of the present application is to provide a method for preparing iron-rich material and battery-grade iron phosphate from ilmenite.

[0008] In order to achieve the above purpose, the present application provides the following technical scheme:

[0009] The present application provides a method for preparing iron-rich material and battery-grade iron phosphate from ilmenite, which comprises the following steps:

[0010] (1) A binder and appropriate water are added to ilmenite powder, the mixture is uniformly mixed to obtain a mixture, the mixture is pelletized to obtain ilmenite pellets, and the ilmenite pellets are dried and oxidized to obtain oxidized pellets;

[0011] (2) The oxidized pellets obtained in step (1) are placed in hydrogen for reduction treatment to obtain reduced ilmenite pellets;

[0012] (3) crushing and screening the reduced ilmenite pellets obtained in step (2) to obtain reduced ilmenite powder, adding the reduced ilmenite powder and a rusting agent into water, and introducing oxygen to obtain a rusted ilmenite;

[0013] (4) separating the rusted ilmenite obtained in step (3) to obtain the titanium-rich material and ilmenite slag;

[0014] (5) adding a mixed acid solution of sulfuric acid and phosphoric acid to the ilmenite slag obtained in step (4), and heating and stirring to react, and filtering to obtain a leaching filtrate and a titanium-rich residue;

[0015] (6) adjusting the pH of the filtrate obtained in step (5) and heating and stirring to react at a set temperature, and then aging and filtering to obtain crude iron phosphate;

[0016] (7) calcining the crude iron phosphate obtained in step (6) to obtain the battery-grade iron phosphate.

[0017] Further, in step (1), the ilmenite powder D 90 < 74 μm, the binder is added in an amount of 0.1% to 2%, and the moisture is 3% to 10%.

[0018] Further, in step (1), the ilmenite pellets are dried and oxidized in a chain grate, the drying treatment is a combination of blast drying and suction drying, the blast drying time is 3 to 4 min, the air speed is 0.5 to 1.5 m / s, and the temperature is 200 to 250°C;

[0019] the suction drying time is 3 to 6 min, the air speed is 0.5 to 1.5 m / s, and the temperature is 250 to 350°C;

[0020] the oxidation temperature is 850 to 950°C, the oxidation time is 10 to 120 min, the air speed is 2.0 to 2.4 m / s, and the oxidation gas is air, oxygen, or a mixture of both.

[0021] Further, in step (2), the reduction temperature is 800 to 900°C, the reduction time is 30 to 90 min, and the hydrogen gas flow rate is 5 to 20 L / min.

[0022] Further, in step (3), the reduced ilmenite powder D 90 < 74 μm, the liquid-solid ratio of the ilmenite powder to water is 5 to 50:1, the rusting temperature is 30 to 80°C, the rusting agent is ammonium chloride, the solution concentration is 0.5 to 3.0 wt.%, the oxygen gas blowing rate is 5 to 30 x 10 3 L / (m 3 ·min), and the oxygen gas is introduced for 6 to 12 h.

[0023] Further, in step (4), the rusted titaniferous material is separated by a shaking table to obtain the titanium-rich material and titaniferous slag.

[0024] Further, in step (5), the titaniferous slag is crushed to control the mass fraction of iron in the titaniferous slag powder D 90 <37 μm, the mass fraction of iron in the titaniferous slag is ≥40 wt. %.

[0025] Further, in step (5), the liquid-solid ratio of the mixed acid solution to the titaniferous slag powder is 2:1-5:1, the concentration of sulfuric acid is 2-4 mol / L, and the molar ratio of phosphoric acid to iron in the titaniferous slag is 0.9-1.3.

[0026] Further, in step (5), the heating temperature is 30-80℃, and the heating and stirring time is ≥0.5h.

[0027] Further, in step (5), the titanium dioxide grade in the titanium-rich filter residue is high, and the titanium-rich material is recycled.

[0028] Further, in step (6), ammonia water is added to adjust the pH of the solution to 1.5-2.8, the heating temperature is 30-80℃, the heating time is ≥0.5h, and the aging time is 0.5-2h.

[0029] Further, in step (7), the calcination temperature is 500-800℃, and the calcination time is 1-5h.

[0030] The method and device of the application have the advantages of low acid consumption, high iron leaching rate, high purity of iron phosphate, easy control of precipitated products, few impurities, simple process, wider raw material sources, and the like, and the prepared high-value-added iron phosphate can meet the corresponding battery-grade iron phosphate standard.

[0031] The application discloses a method for preparing a titanium-rich material and battery-grade iron phosphate from ilmenite, which solves the problems of complex process, large amount of reagent consumption, many impurities in products, poor quality of iron phosphate, large amount of water flushing, and the like in the process of preparing iron phosphate by using traditional acid leaching (+ oxidation)-phosphorus salt-ammonia water process of iron raw materials.

[0032] Compared with the prior art, the application has the advantages of:

[0033] (1) The application is a method for preparing titanium-rich material and battery-grade iron phosphate from ilmenite, which replaces the solid carbon reduction process with hydrogen reduction, thereby improving the separation efficiency of titanium and iron and the grade of titanium-rich material, and reducing the emission of carbon dioxide, smoke dust and waste gas pollutants during the reduction and corrosion process.

[0034] (2) The application is a method for preparing titanium-rich material and battery-grade iron phosphate from ilmenite, which uses iron-rich ilmenite slag as a raw material for preparing battery-grade iron phosphate, greatly expanding the source of raw materials for preparing iron phosphate.

[0035] (3) The application is a method for preparing titanium-rich material and battery-grade iron phosphate from ilmenite, which uses a sulfuric acid-phosphoric acid mixed acid leaching system, and phosphoric acid can form a complex Fe(HPO4) 2- with iron ions, which not only greatly promotes the complete dissolution and conversion of iron oxides, but also improves the leaching rate of ilmenite slag, reduces the amount of sulfuric acid used, and reduces the amount of ammonia used in the subsequent precipitation of iron phosphate, thereby reducing the generation of ammonium sulfate impurities; at the same time, the high-grade titanium dioxide in the remaining titanium-rich filter residue can be recycled into the titanium-rich material. In addition, the formation of phosphorus-iron complexes can control the concentration of iron ions in the leaching solution, reducing the generation of iron hydroxide impurities in the iron phosphate product. In addition, phosphoric acid, as a ternary strong acid, can be used as a buffer for the leaching system, which can effectively buffer the pH change during the leaching process, making the leaching process rate controllable.

[0036] (4) The process has high iron recovery rate, low sulfuric acid and ammonia consumption, and high purity of the obtained iron phosphate product, which is green and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings and tables needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0038] Figure 1 The process flow chart of the embodiment of the application.

[0039] Figure 2 The XRD characterization of the iron phosphate obtained in Example 1. DETAILED DESCRIPTION

[0040] The following is a specific implementation case given by the inventor, which needs to be explained that these embodiments are only to better illustrate the application, and are not used to limit the scope of the application. Any parameter selection within the technical solution of the application is within the scope of the application.

[0041] Table 1 Chemical composition of ilmenite used in the application

[0042]

[0043] The application will be further described below by specific examples and drawings.

[0044] Example 1

[0045] A method for preparing a titanium-rich material and a battery-grade iron phosphate from ilmenite, comprising the following steps:

[0046] 1) Mix ilmenite with 2.0% binder polyvinyl alcohol, then perform balling under the conditions of 8.0% moisture and 12 min balling time, and the resulting green balls have a drop strength of 4.5 times per ball and a compressive strength of 10.2 N per ball, and a burst temperature of 420℃;

[0047] 2) Dry and oxidize the obtained green balls on a chain grate, wherein the drying is a combination of blast drying and suction drying, the blast drying time is 3 min, the air speed is 1.2 m / s, and the temperature is 200℃; the suction drying time is 3 min, the air speed is 1.2 m / s, and the temperature is 350℃; the oxidation temperature is 850℃, the oxidation time is 30 min, the air speed is 2.4 m / s, and the compressive strength of the oxidized balls is 1050 N per ball;

[0048] 3) Perform hydrogen-based direct reduction of the obtained oxidized balls under the conditions of a reduction temperature of 800℃, a reduction time of 90 min, and a H2 flow rate of 15 L / min, and the resulting metallization rate is 87.87%;

[0049] 4) After roasting the reduced ore, perform gravity separation of the corrosion product obtained by blowing oxygen at a rate of 15×10 3 L / (m3·min) into the ammonium chloride solution at a concentration of 2.0% under the conditions of a liquid-solid ratio of 10:1, a temperature of 75℃, a stirring rate of 600 r / min, and a corrosion time of 8 h, and the obtained titanium-rich material has a TiO2 grade of 79.44% and a recovery rate of 88.32%; the iron grade in the iron and titanium-containing slag is 66.36%, and the TiO2 content is 3.25%;

[0050] 5) Perform crushing treatment on the titanium slag, control the D 90 <37 μm of the titanium slag powder, the mass fraction of iron in the titanium slag is ≥40 wt.%, add a mixed acid solution of 3 mol / L sulfuric acid and concentrated phosphoric acid to the titanium slag powder, the liquid-solid ratio of the mixed acid solution to the titanium slag is 4:1, the mol ratio of phosphoric acid substance to iron substance in the titanium slag is 1.0, filter the filtrate and titanium-rich filter residue obtained after heating and stirring at 70℃ for 2 h, and the TiO2 grade of the titanium-rich filter residue is 75.06%;

[0051] 6) To the filtrate, ammonia water was added to adjust the pH of the solution to 2.0, heated and stirred at 60℃ for 20 min, and after aging for 30 min, the crude iron phosphate was obtained by filtration;

[0052] 7) The crude iron phosphate was calcined at 650℃ for 2h, and after cooling, the battery-grade iron phosphate was obtained, and the process flow chart is shown in Figure 1

[0053] Table 2 is a table of chemical composition of titanium-iron slag. As can be seen from the table, the content of impurity ion elements is relatively high.

[0054] Table 3 is the product quality of the battery-grade iron phosphate prepared in the embodiment. Compared with Comparative Example 1, the metallization rate of the reduced roasted ore is increased after hydrogen reduction, the TiO2 grade and recovery rate in the titanium-rich material are increased, and the iron grade in the iron-titanium slag is increased, indicating that the iron-titanium separation effect is improved.

[0055] Figure 2 The XRD characterization of the iron phosphate obtained in Example 1 is shown in the table. The battery-grade iron phosphate obtained by the present application meets the standard requirements of “HG / T 4701-2014 Battery Iron Phosphate”. The purity of the obtained lithium phosphate is 99.91%. As can be seen from the XRD characterization of the iron phosphate, the characteristic peaks of the calcined iron phosphate sample are relatively obvious, the crystallinity is high, and the number of impurity peaks is small. Compared with the standard iron phosphate card, the material characteristic peak height is consistent, which fully shows that the obtained product is iron phosphate.

[0056] Table 2 Chemical composition of titanium-iron slag

[0057]

[0058] Table 3 Standard requirements of “HG / T 4701-2014 Battery Iron Phosphate” and element content of iron phosphate product

[0059]

[0060] Example 2

[0061] A method for preparing a titanium-rich material and a battery-grade iron phosphate from ilmenite, comprising the following steps:

[0062] 1) The ilmenite was mixed with 2.0% binder polyvinyl alcohol, and then balling was carried out under the conditions of water content 8.0% and balling time 12 min, and the obtained green ball had a drop strength of 4.5 times per ball and a compression strength of 10.2 N per ball, and the burst temperature was 420℃;

[0063] ​2) drying and oxidizing the obtained green pellets on a chain grate, the drying being combined with updraft drying and downdraft drying, the updraft drying being performed for 3 min at a wind speed of 1.2 m / s and a temperature of 200℃, the downdraft drying being performed for 3 min at a wind speed of 1.2 m / s and a temperature of 350℃, the oxidizing being performed at a temperature of 850℃ for 60 min at a wind speed of 2.4 m / s, and the oxidized pellet having a compressive strength of 1050 N / pellet;

[0064] 3) directly reducing the obtained oxidized pellet under hydrogen, the reduction being performed at a reduction temperature of 850℃ for 60 min at a H2 flow rate of 15 L / min, and the obtained metallization rate being 90.24%;

[0065] 4) rusting the reduced roasted ore at a liquid-solid ratio of 10:1 at a temperature of 75℃ at a stirring speed of 600 r / min for 8 h in the presence of an ammonium chloride solution having a concentration of 2.0%, and at an oxygen blowing rate of 15 x 10 3 L / (m 3 ·min), and then separating the rusting product by gravity separation, the obtained Ti-rich material having a TiO2 grade of 84.56% and a recovery rate of 92.34%, and the iron-Ti-containing slag having an iron grade of 60.67% and a TiO2 content of 4.68%;

[0066] 5) crushing the iron-Ti-containing slag, controlling the D 90 <37 μm of the iron-Ti-containing slag powder, and controlling the mass fraction of iron in the iron-Ti-containing slag to be ≥40 wt.%, adding a mixed acid solution of sulfuric acid and concentrated phosphoric acid to the iron-Ti-containing slag powder, controlling the liquid-solid ratio of the mixed acid solution to the iron-Ti-containing slag to be 4:1, and controlling the mol ratio of phosphoric acid substance to iron substance in the iron-Ti-containing slag to be 1.0, filtering the obtained leaching filtrate and Ti-rich filter residue after heating and stirring at 70℃ for 2 h, and the Ti-rich filter residue having a TiO2 grade of 55.37%;

[0067] 6) adjusting the pH of the filtrate to 2.0 by adding ammonia water, heating and stirring the solution at 60℃ for 20 min, and filtering the obtained crude iron phosphate after aging for 30 min;

[0068] 7) calcining the crude iron phosphate at 700℃ for 2 h, and obtaining the battery-grade iron phosphate after cooling, and Table 4 shows the product quality of the battery-grade iron phosphate prepared in this embodiment.

[0069] Table 4 Standard requirements and product element contents of battery-grade iron phosphate according to HG / T 4701-2014

[0070]

[0071] Example 3

[0072] A method for preparing Ti-rich material and battery-grade iron phosphate from ilmenite, comprising the following steps:

[0073] 1) mix ilmenite with 2.0% binder polyvinyl alcohol; then perform balling under the conditions of moisture 8.0%, balling time 12 min, to obtain green balls with drop strength 4.5 times per ball and compressive strength 10.2 N per ball, and burst temperature 420℃;

[0074] 2) dry and oxidize the obtained green balls on a chain grate, wherein the drying is combined drying by blowing and drying by suction, the blowing drying time is 3 min, the air speed is 1.2 m / s, and the temperature is 200℃; the suction drying time is 3 min, the air speed is 1.2 m / s, and the temperature is 350℃; the oxidation temperature is 850℃, the oxidation time is 50 min, and the air speed is 2.4 m / s, and the compressive strength of the oxidized pellets is 1050 N per ball;

[0075] 3) perform hydrogen-based direct reduction on the obtained oxidized pellets under the conditions of reduction temperature 900℃, reduction time 60 min, and H2 flow rate 15 L / min, to obtain a metallization rate of 93.55%;

[0076] 4) perform roasting on the reduced roasted ore under the conditions of liquid-solid ratio 10:1, temperature 75℃, stirring rate 600 r / min, ammonium chloride solution concentration 2.0%, oxygen blowing rate 15×10 3 L / (m 3 ·min, and rusting time 8 h, and then separate the rusting product by gravity separation, to obtain a titanium-rich material with TiO2 grade 87.32% and recovery rate 94.45%; and an iron-titanium-containing slag with iron grade 60.78% and TiO2 content 4.56%;

[0077] 5) perform crushing treatment on the titanium-iron slag, control the titanium-iron slag powder D 90 <37 μm, and the mass fraction of iron in the titanium-iron slag ≥40 wt.%, add a mixed acid solution of 3 mol / L sulfuric acid and concentrated phosphoric acid to the titanium-iron slag powder, the liquid-solid ratio of the mixed acid solution to the titanium-iron slag is 4:1, and the mol ratio of phosphoric acid substance to iron substance in the titanium-iron slag is 1.0, filter the titanium-rich residue and leaching filtrate obtained after heating and stirring at 75℃ for 2.5 h, and the TiO2 grade of the titanium-rich residue is 72.44%;

[0078] 6) add ammonia water to the filtrate to adjust the solution pH to 2.0, heat and stir at 60℃ for 20 min, and filter the crude iron phosphate obtained after aging for 30 min;

[0079] 7) calcine the crude iron phosphate at 700℃ for 2 h, and obtain battery-grade iron phosphate after cooling, and Table 5 shows the element content of the battery-grade iron phosphate prepared in this example.

[0080] Table 5 Standard requirements and element content of iron phosphate product according to HG / T 4701-2014 Iron Phosphate for Batteries

[0081]

[0082] Comparative Example 1

[0083] A method for utilizing ilmenite, comprising the following steps:

[0084] 1) mixing ilmenite with 2.0% binder polyvinyl alcohol, and then performing balling under the conditions of moisture 8.0% and balling time 12 min, to obtain green balls with falling strength 4.5 times per ball and compressive strength 10.2 N per ball, and a burst temperature of 420℃;

[0085] 2) drying and oxidizing the obtained green balls on a chain grate, wherein the drying is a combination of updraft drying and downdraft drying, the updraft drying is performed for 3 min at a wind speed of 1.2 m / s and a temperature of 200℃, the downdraft drying is performed for 3 min at a wind speed of 1.2 m / s and a temperature of 350℃, the oxidation is performed at a temperature of 850℃ for 40 min at a wind speed of 2.4 m / s, and the compressive strength of the oxidized balls is 1050 N per ball;

[0086] 3) reducing the obtained oxidized balls in a coal-based reduction furnace under the conditions of a reduction temperature of 1150℃, a reduction time of 120 min, and a C / Fe mass ratio of 0.6, to obtain a metallization rate of 84.67%;

[0087] 4) rusting the reduced roasted ore under the conditions of a liquid-solid ratio of 10:1, a temperature of 75℃, a stirring rate of 600 r / min, a concentration of ammonium chloride solution of 2.0%, an oxygen blowing rate of 15 x 10 3 L / (m 3 ·min, and a rusting time of 8 h, and then separating the rusting products by gravity separation, to obtain a titanium-rich material with a TiO2 grade of 75.67% and a recovery rate of 85.66%, and a titanium-iron-containing slag with an iron grade of 59.22% and a TiO2 content of 6.67%;

[0088] 5) adding a 4 mol / L sulfuric acid solution to the ilmenite slag powder, and filtering the filtrate and a titanium-rich filter residue obtained after heating and stirring the acid solution and the ilmenite slag at a liquid-solid ratio of 5:1 at 70℃ for 2 h, the titanium-rich filter residue having a TiO2 grade of 55.37%;

[0089] 6) adding tri-sodium phosphate to the filtrate at a molar ratio of 1.0 to the amount of iron in the ilmenite slag, adjusting the pH of the solution to 2.0 with ammonia water, heating and stirring the solution at 60℃ for 20 min, and filtering the crude iron phosphate obtained after aging for 30 min;

[0090] 7) calcining the crude iron phosphate at 600℃ for 4 h, and obtaining iron phosphate after cooling.

[0091] Table 6 is the chemical composition of the titanium slag in Comparative Example 1. Table 7 is the chemical composition table of the iron phosphate prepared in Comparative Example 1, and it can be seen from the table that the content of impurity ion elements is relatively high. The product quality of the iron phosphate prepared in Comparative Example 1 cannot meet the standard requirements of HG / T 4701-2014 Iron Phosphate for Batteries. The phosphorus-iron ratio far exceeds the normal phosphorus-iron ratio requirement, and the product contains a large amount of iron hydroxide and ammonium sulfate impurities. This is because the pH value of the acid leaching solution is too low, and a large amount of ammonia water needs to be added to adjust the pH value when precipitating the iron phosphate. The form of iron in the leaching solution is single, only Fe 3+ The pH value range of the precipitation of Fe(OH)3 and FePO4 is overlapped, so that the crude iron phosphate product contains a large amount of impurities. Even if the amount of water used in the filtration process is increased, it cannot be improved.

[0092] Table 6 is the chemical composition of the titanium slag in Comparative Example 1. Table 7 is the chemical composition table of the iron phosphate prepared in Comparative Example 1, and it can be seen from the table that the content of impurity ion elements is relatively high. The product quality of the iron phosphate prepared in Comparative Example 1 cannot meet the standard requirements of HG / T 4701-2014 Iron Phosphate for Batteries. The phosphorus-iron ratio far exceeds the normal phosphorus-iron ratio requirement, and the product contains a large amount of iron hydroxide and ammonium sulfate impurities. This is because the pH value of the acid leaching solution is too low, and a large amount of ammonia water needs to be added to adjust the pH value when precipitating the iron phosphate. The form of iron in the leaching solution is single, only Fe

[0093]

[0094] Table 7 Standard requirements of HG / T 4701-2014 Iron Phosphate for Batteries and element content of iron phosphate product

[0095]

[0096] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples. Any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement methods and shall be within the scope of protection of the present application.

Claims

1. A method for preparing titanium-rich materials and battery-grade iron phosphate using ilmenite, characterized in that, Includes the following steps: (1) Add binder and appropriate water to ilmenite powder, mix evenly to obtain a mixture, pelletize the mixture to obtain ilmenite pellets, dry and oxidize the ilmenite pellets to obtain oxidized pellets; (2) The oxidized pellets obtained in step (1) are placed in hydrogen gas for reduction treatment to obtain reduced ilmenite pellets; (3) The reduced ilmenite pellets obtained in step (2) are crushed and screened to obtain reduced ilmenite powder. The reduced ilmenite powder and rust-causing agent are added to water and oxygen is introduced to obtain rusted ilmenite. (4) Separate the rusted titanium-iron material obtained in step (3) to obtain the titanium-rich material and titanium-iron slag; (5) Add a mixed acid solution of sulfuric acid and phosphoric acid to the ferrotitanium slag obtained in step (4), heat and stir to react, and filter to obtain leachate and titanium-rich filter residue. (6) Adjust the pH of the filtrate obtained in step (5) and heat and stir it at a set temperature. Then, after aging and filtration, crude iron phosphate is obtained. (7) The crude iron phosphate obtained in step (6) is calcined and cooled to obtain the battery-grade iron phosphate; In step (1), the ilmenite pellets are dried and oxidized in a chain grate machine. The drying process is a combination of forced air drying and forced air drying. The forced air drying time is 3~4 min, the wind speed is 0.5~1.5 m / s, and the temperature is 200~250℃. The drying time is 3-6 minutes, the air velocity is 0.5-1.5 m / s, and the temperature is 250-350℃. The oxidation treatment temperature is 850~950℃, the oxidation time is 10~120min, the wind speed is 2.0~2.4m / s, and the gas introduced for oxidation is air, oxygen or a mixture of both; In step (2), the reduction temperature is 800~900℃, the reduction time is 30~90min, and the hydrogen flow rate is 5~20L / min.

2. The method for preparing titanium-rich materials and battery-grade iron phosphate using ilmenite according to claim 1, characterized in that, In step (1), the ilmenite powder D 90 <74μm, the amount of binder added is 0.1%~2%, and the amount of water is 3%~10%.

3. The method for preparing titanium-rich materials and battery-grade iron phosphate using ilmenite according to claim 1, characterized in that, In step (3), the reduced ilmenite powder D 90 <74μm, the liquid-to-solid ratio of reduced ilmenite powder to water is 5~50:1, the corrosion temperature is 30~80℃, the etchant is ammonium chloride, the solution concentration is 0.5~3.0wt.%, and the oxygen inlet rate is 5~30×10 3 L / (m 3 •min), oxygen is introduced for 6~12h.

4. The method for preparing titanium-rich materials and battery-grade iron phosphate using ilmenite according to claim 1, characterized in that, In step (5), the ilmenite slag is pulverized to control the powder density (D). 90 <37μm, iron mass fraction in ilmenite slag ≥40wt.%.

5. The method for preparing titanium-rich materials and battery-grade iron phosphate using ilmenite according to claim 4, characterized in that, In step (5), the liquid-solid ratio of the mixed acid solution to the titanium iron slag powder is 2:1 to 5:1, the sulfuric acid concentration is 2 to 4 mol / L, the ratio of phosphate to iron in the titanium iron slag is 0.9 to 1.3 mol, the heating temperature is 30 to 80℃, and the heating and stirring time is ≥0.5h.

6. The method for preparing titanium-rich materials and battery-grade iron phosphate using ilmenite according to claim 4, characterized in that, In step (5), the titanium dioxide in the titanium-rich filter residue is of high grade and is incorporated into the titanium-rich material for recycling.

7. The method for preparing titanium-rich materials and battery-grade iron phosphate using ilmenite according to claim 1, characterized in that, In step (6), ammonia water is added to adjust the pH of the solution to 1.5~2.8, the heating temperature is 30~80℃, the heating time is ≥0.5h, and the aging time is 0.5~2h.

8. The method for preparing titanium-rich materials and battery-grade iron phosphate using ilmenite according to claim 1, characterized in that, In step (7), the calcination temperature is 500~800℃ and the calcination time is 1~5h.

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