Method for deeply reducing vanadium, tungsten, molybdenum and titanium in organophosphate extraction agent

Abstract

The invention provides a method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organophosphate extraction agent, which comprises the following steps: mixing the organophosphate extraction agent and a first stripping agent reducing acid solution for countercurrent stripping, and obtaining a low-vanadium extraction agent and a vanadium stripping solution after the stripping is completed; mixing the low-vanadium extracting agent and a second stripping agent oxalic acid solution for countercurrent stripping, and obtaining a low-vanadium, tungsten and molybdenum extracting agent and a tungsten and molybdenum stripping solution after the stripping is completed; mixing a low-vanadium, tungsten and molybdenum extracting agent and a third stripping agent hydrogen peroxide and dilute sulphuric acid mixed solution, and carrying out countercurrent stripping to obtain a low-vanadium, tungsten, molybdenum and titanium extracting agent and a titanium stripping solution after the stripping is completed; the low-vanadium, tungsten, molybdenum and titanium extraction agent and a sulfurous acid solution are mixed for countercurrent pickling, and a regenerated extraction agent and a pickling solution are obtained after pickling is completed. According to the method, the loss rate of the organic phase is low, vanadium, tungsten, molybdenum and titanium elements in the organic phosphate extraction agent can be deeply removed and recycled, and no waste liquid is generated.

Description

Technical Field

[0001] The invention relates to metallurgical technology, and in particular to a method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant. Background Art

[0002] Extraction is to transfer the target component from one solvent to another by utilizing the difference in solubility or distribution coefficient of the target component in two immiscible (or slightly soluble) solvents. In the field of hydrometallurgy, compared with other separation methods such as precipitation, ion exchange, and membrane separation, solvent extraction has the advantages of high separation efficiency, good separation effect, large production capacity, high metal recovery rate, low reagent consumption, simple equipment, and easy automation and continuous production process. It is the mainstream method for separation, purification, and recovery of metal ions in industry.

[0003] Common organic extractants in industry are divided into acidic extractants, neutral extractants, and amine extractants. In the production of vanadium electrolyte, acidic extractants, such as P204, P507, Cyanex272, etc., are usually used to separate vanadium from impurity elements. With the recycling of organic extractants in the production process, some easily extracted metal ions form relatively stable complexes with the extractants and are not easy to be stripped, such as tungsten, molybdenum, titanium, etc. These metal ions gradually enrich in the extractants and occupy organic extraction sites, resulting in a decrease in the amount of organically extracted vanadium, a decrease in the separation ability of metal impurities, a slow phase separation rate, and even "poisoning" or failure of the extractant.

[0004] The Chinese patent (publication number CN 102534213 B) describes that the organic phase extracted from P204 with iron poisoning is used as raw material, and the organic phase extracted from P204 can be de-ironized and detoxified after washing with sodium hydroxide + ammonium bicarbonate solution and regenerated with oxalic acid + sulfuric acid solution and then used for further use. The patent only detoxifies the impurity element iron in the organic phase extracted from P204, and does not mention the detoxification method and recovery method of vanadium, tungsten, molybdenum, and titanium in the organic phase extracted from P204. Washing the organic phase extracted from P204 with sodium hydroxide + ammonium bicarbonate will cause saponification reaction of P204, increase water solubility, and increase the loss rate of P204. The Chinese patent (publication number CN115961156A) describes that the aged organic extractant of the P204 impurity removal extraction line can be regenerated by removing scandium from the P204 organic extractant after alkali washing and acid washing, and the metal scandium can be recovered. The patent only detoxifies and recovers the impurity element scandium in the organic phase extracted by P204, and does not mention the detoxification method and recovery method of vanadium, tungsten, molybdenum, and titanium in the organic phase extracted by P204. The use of alkali washing for the organic phase extracted by P204 will cause saponification reaction of P204, enhance water solubility, and increase the loss rate of P204. The Chinese patent (CN112063838A) describes that the organic extractant detoxification and regeneration can be completed after the impurity-containing P204 and P507 extractants are washed with hydrochloric acid, washed with oxalic acid, and treated with activated white earth. The patent does not mention the recovery of valuable metals, and the use of activated white earth regeneration has poor effect, generates a large amount of waste, has high regeneration cost, and has a high organic phase loss rate. The Chinese patent (CN106086406 B) describes that the organic extractant containing impurities can be detoxified and regenerated by subjecting it to acid reaction, alkali reaction, inorganic acid reaction, and pure water treatment. The patent does not mention the recovery of valuable metals.

[0005] At present, the detoxification and regeneration of organic extractants has problems such as generating a large amount of waste, the inability to recycle valuable metals, and high organic phase loss. In addition, there is no method for deeply reducing the vanadium, tungsten, molybdenum, and titanium in organic phosphate extractants and their recovery methods. Summary of the invention

[0006] The purpose of the present invention is to propose a method for deeply reducing vanadium, tungsten, molybdenum and titanium in organic phosphate extractants in view of the problems that the current detoxification and regeneration of organic extractants produces a large amount of waste, valuable metals cannot be recycled and utilized, and the organic phase loss is high. The method has a low organic phase loss rate, can deeply remove vanadium, tungsten, molybdenum and titanium elements in organic phosphate extractants, and recycle them without generating any waste liquid. The method has very good application prospects and large-scale industrial promotion potential in the field of extractant recovery.

[0007] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising", etc. and similar meanings, as well as closed-ended "composed of", "composed of", etc. and similar meanings.

[0008] To achieve the above object, the technical solution adopted by the present invention is: a method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant, comprising the following steps:

[0009] Step 1, reduction stripping to extract vanadium, using a reducing acid solution as a first stripping agent, mixing an organic phosphate extractant and the first stripping agent for countercurrent stripping, and obtaining a low-vanadium extractant and a vanadium stripping solution after stripping;

[0010] Step 2: extracting tungsten and molybdenum by complex stripping, using oxalic acid solution as the second stripping agent, mixing the low-vanadium extractant obtained in step 1 with the second stripping agent for countercurrent stripping, and obtaining a low-vanadium, tungsten, and molybdenum extractant and a tungsten and molybdenum stripping solution after stripping;

[0011] Step 3, complex stripping to extract titanium, using a mixed solution of hydrogen peroxide and dilute sulfuric acid as the third stripping agent, mixing the low-vanadium, tungsten, and molybdenum extractant obtained in step 2 and the third stripping agent for countercurrent stripping, and obtaining a low-vanadium, tungsten, molybdenum, and titanium extractant and a titanium stripping solution after stripping;

[0012] Step 4, reductive pickling, mixing the low vanadium, tungsten, molybdenum, titanium extractant obtained in step 3 with the sulfurous acid solution for countercurrent pickling, and obtaining a regenerated extractant and a pickling solution after the pickling is completed.

[0013] Furthermore, the organophosphate extractant in step 1 is one or more of P507, P204 and Cyanex272.

[0014] Furthermore, the vanadium content in the organic phosphate extractant in step 1 is 1-2 g / L, the tungsten content is 3-5 g / L, the molybdenum content is 3-5 g / L, and the titanium content is 5-8 g / L.

[0015] Furthermore, the reducing acid solution in step 1 is one or more of sulfuric acid, hydrochloric acid, and phosphoric acid with a free hydrogen ion concentration of 1.0 to 5.0 mol / L, wherein V 3+ =0.5~2.0mol / L. Preferably, the reducing acid solution is one or more of sulfuric acid, hydrochloric acid, and phosphoric acid with a free hydrogen ion concentration of 2.0~4.0mol / L, wherein V 3+ =1.0~2.0mol / L.

[0016] Furthermore, in step 1, the organic phosphate extractant and the first stripping agent are mixed at a ratio of O / A = (10-20): 1 for countercurrent stripping, the stripping stage is 1-4, and the stripping temperature is 20-80° C. Preferably, the organic phosphate extractant and the stripping agent are mixed at a ratio of O / A = (16-20): 1 for countercurrent stripping; preferably, the stripping temperature is 40-60° C.

[0017] Furthermore, the vanadium stripping solution after stripping in step 1 is subjected to aeration deoiling, resin deoiling and activated carbon deoiling in sequence, and then electrolytically reduced and adjusted before being reused as a stripping agent.

[0018] Furthermore, the concentration of the oxalic acid solution in step 2 is 3-8%. In the present invention, unless otherwise specified, % refers to mass percentage.

[0019] Further, in step 2, the low-vanadium extractant obtained in step 1 is mixed with the second stripping agent at a ratio of O / A = (10-20): 1 for countercurrent stripping, the stripping stage is 1-5, and the stripping temperature is 40-60° C. Preferably, the low-vanadium extractant and the stripping agent are mixed at a ratio of O / A = (16-20): 1 for countercurrent stripping; preferably, the stripping temperature is 50-60° C.

[0020] Furthermore, in step 2, the tungsten and molybdenum stripping solutions are subjected to aeration deoiling, resin deoiling and activated carbon deoiling in sequence, and then the temperature is raised to 80-100° C. to hydrolyze and precipitate tungsten and molybdenum, and molybdic acid, tungstic acid and oxalic acid solutions are obtained through solid-liquid separation. The oxalic acid solution can be reused, and the molybdic acid and tungstic acid are dried and calcined to obtain molybdenum oxide and tungsten oxide.

[0021] Furthermore, in step 3, the H2O2 concentration in the mixed solution of hydrogen peroxide and dilute sulfuric acid is 2-8%, and the sulfuric acid concentration is 10-50%. Preferably, the H2O2 concentration in the mixed solution of hydrogen peroxide and dilute sulfuric acid is 3-5%, and the sulfuric acid concentration is 20-40%.

[0022] Further, in step 3, the low vanadium, tungsten, molybdenum extractant obtained in step 2 and the third stripping agent are mixed at a ratio of O / A = (10-20): 1 for countercurrent stripping, the stripping stage is 1-3, and the stripping temperature is 20-40° C. Preferably, the low vanadium, tungsten, molybdenum extractant and the stripping agent are mixed at a ratio of O / A = (18-20): 1 for countercurrent stripping.

[0023] Furthermore, in step 3, the titanium stripping solution is subjected to aeration deoiling, resin deoiling and activated carbon deoiling in sequence, and then the temperature is raised to 90-100° C. to hydrolyze the titanium, and then the titanium is separated into solid and liquid to obtain titanic acid and dilute sulfuric acid, and the dilute sulfuric acid can be reused. The titanic acid is dried and calcined to obtain titanium oxide;

[0024] Furthermore, the aeration gas in step 1, step 2 and step 3 is nitrogen or argon, the gas flow rate is 1.0-3.0 L / min, the aeration pressure is 3.5-4.5 MPa, and the oil removal flow rate is 100-300 L / h.

[0025] Furthermore, the resin in step 1, step 2 and step 3 is an oil-removing resin, and the oil-removing resin is one or more of SV232, SV650, D113, ADS-500, ADS-600 and ADS-277, and the oil removal flow rate is 2 to 5 BV.

[0026] Furthermore, the activated carbon in step 1, step 2 and step 3 is coconut shell activated carbon with a particle size of 4 to 8 mm, an iodine value of 800 to 1200, and an oil removal flow rate of 2 to 5 BV.

[0027] Further, in step 4, the low vanadium, tungsten, molybdenum, titanium extractant obtained in step 3 and the sulfurous acid solution are mixed at a ratio of O / A = (10-20): 1 for countercurrent pickling, the pickling level is 1-3, and the pickling temperature is 20-40° C. Preferably, the low vanadium, tungsten, molybdenum, titanium extractant and the sulfurous acid solution are mixed at a ratio of O / A = (10-15): 1 for countercurrent pickling.

[0028] Furthermore, in step 4, sulfur dioxide is added to the pickling solution, which can be reused.

[0029] The basic principle of the method for deeply reducing vanadium, tungsten, molybdenum and titanium in the organic phosphate extractant of the present invention is as follows:

[0030] (1) Reduction stripping to remove vanadium: V 3+ (A) +VO 2+(O) =2VO 2+ (A)

[0031] (2) Complex stripping to remove molybdenum: C2H2O 4(A) +2OH - (A) +MoO2 2+ (O) =H2[MoO3(C2O4)]·H2O (A)

[0032] (3) Complex stripping to remove tungsten: C2H2O 4(A) +H2WO 4(O) =H2[WO3(C2O4)]·H2O (A)

[0033] (4) Molybdenum precipitation by hydrolysis: H2[MoO3(C2O4)]·H2O (A) +H2O=H2MoO4·H2O(S) +H2C2O4

[0034] (5) Hydrolysis precipitation of tungsten: H2[WO3(C2O4)]·H2O (A) +H2O=H2WO4·H2O (S) +H2C2O4

[0035] (6) Calcinated molybdenum oxide: H2MoO4·H2O (S) =MoO 3(S) +2H2O

[0036] (7) Calcined tungsten oxide: H2WO4·H2O (S) =WO 3(S) +2H2O

[0037] (8) Complex stripping to remove titanium: 2H2O 2(A) +H2TiO 3(O) =[TiO(H2O2)2] 2+ (A) +2OH -

[0038] (9) Hydrolysis precipitation of titanium: [TiO(H2O2)2] 2+ (A) +2OH - =H2TiO3·H2O (S) +H2O+O2

[0039] (10) Calcined titanium oxide: H2TiO3·H2O (S) =TiO 2(S) +2H2O

[0040] (11) Pickling to remove H2O2: H2O2+SO3 2- =H2O+SO4 2-

[0041] The method of deeply reducing vanadium, tungsten, molybdenum and titanium in the organic phosphate extractant of the present invention has the following advantages compared with the prior art:

[0042] 1) The present invention can achieve deep removal of vanadium, tungsten, molybdenum and titanium by organic phosphate extractants, with a removal rate of >99%;

[0043] 2) The present invention has a short regeneration process, simple operation, low impurity removal cost, and high organic phase recovery rate, and has very good application prospects and large-scale industrial promotion potential in the field of extractant recovery.

[0044] 3) The reaction process of the present invention does not generate any waste and can also realize the recycling of valuable metals, which is in line with my country's goal of developing a circular economy and energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The present invention is a flow chart of a method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant. DETAILED DESCRIPTION

[0046] The present invention is further described below with reference to the examples. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0047] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0048] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0049] In this specification, the numerical range expressed using "above" or "below" means a numerical range including the number.

[0050] In this specification, the word "may" includes both performing a certain process and not performing a certain process.

[0051] In this specification, the use of "optional" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0052] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 15-25°C.

[0053] In this manual, the reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0054] Example 1

[0055] This embodiment discloses a method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant, comprising the following steps:

[0056] The vanadium content in the P507 extractant before testing was 1.5 g / L, the tungsten content was 3.2 g / L, the molybdenum content was 4.4 g / L, and the titanium content was 6.7 g / L.

[0057] Step 1: Reduction stripping to extract vanadium. 3+ =1.5mol / L, H +=2.5mol / L sulfuric acid solution was used as the stripping agent and the P507 extractant was subjected to 4-stage countercurrent stripping at a temperature of 40°C according to the ratio of O / A=20:1. After the stripping, a low-vanadium P507 extractant and a vanadium stripping solution were obtained. The vanadium stripping solution was subjected to aeration deoiling, SV232 resin deoiling and activated carbon deoiling at a flow rate of 3BV / h, and then electrolytic reduction and adjusted to V 3+ =1.5mol / L, H + =2.5mol / L is used repeatedly as stripping agent;

[0058] Step 2, complex stripping to extract tungsten and molybdenum. Use 5% oxalic acid solution as stripping agent, and carry out 4-stage countercurrent stripping at 50°C with the extractant and stripping agent obtained in step 1 at a ratio of O / A=20:1. After stripping, low vanadium, tungsten and molybdenum extractants and tungsten and molybdenum stripping solutions are obtained. The tungsten and molybdenum stripping solutions are subjected to aeration deoiling, SV232 resin deoiling and activated carbon deoiling at a flow rate of 3BV / h, and then heated to 95°C to hydrolyze and precipitate tungsten and molybdenum. After solid-liquid separation, oxalic acid solution is obtained. The oxalic acid solution can be reused. Molybdenum oxide and tungsten oxide are obtained after drying and calcination of molybdic acid and tungstic acid.

[0059] Step 3, complex stripping to extract titanium. A mixed solution containing 5% H2O2 and 25% sulfuric acid is used as the stripping agent, and the extractant and stripping agent obtained in step 2 are subjected to three-stage countercurrent stripping at a temperature of 40°C according to a ratio of O / A=20:1. After the stripping is completed, low-vanadium, tungsten, molybdenum, titanium extractant and titanium stripping solution are obtained; the titanium stripping solution is subjected to aeration deoiling, SV232 resin deoiling and activated carbon deoiling at a flow rate of 3BV / h, and then the temperature is raised to 95°C for hydrolysis and precipitation of titanium. Titanium metatitanic acid and dilute sulfuric acid are obtained through solid-liquid separation. The dilute sulfuric acid can be reused. Titanium oxide is obtained after the titanium metatitanic acid is dried and calcined;

[0060] Step 4, reductive pickling: The extractant obtained in step 3 and the sulfurous acid solution are subjected to three-stage countercurrent pickling at a temperature of 40°C according to a ratio of O / A=15:1. After the pickling is completed, the regenerated extractant and pickling solution are obtained, which can be reused after adding sulfur dioxide.

[0061] After impurities are removed through the above steps, the vanadium content in the P507 extractant is 0.0055 g / L, the tungsten content is 0.015 g / L, the molybdenum content is 0.020 g / L, and the titanium content is 0.030 g / L after detection and treatment. The P507 extractant removes vanadium, tungsten, molybdenum, and titanium with a removal rate greater than 99.5%. The recovery rate of the P507 extractant is 98.4%, and the recovery rates of the valuable metals vanadium, tungsten, molybdenum, and titanium are greater than 99.0%.

[0062] Example 2

[0063] This embodiment discloses a method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant, comprising the following steps:

[0064] The vanadium content in the P204 extractant before testing was 2.0 g / L, the tungsten content was 4.5 g / L, the molybdenum content was 4.8 g / L, and the titanium content was 7.2 g / L.

[0065] Step 1: Reduction stripping to extract vanadium. 3+ =2.0mol / L, H + =3.0mol / L hydrochloric acid solution as the stripping agent and P204 extractant according to the ratio of O / A=18:1, and three-stage countercurrent stripping is carried out at a temperature of 60°C. After the stripping is completed, low-vanadium P204 extractant and vanadium stripping solution are obtained; the vanadium stripping solution is subjected to aeration deoiling, SV650 resin deoiling and activated carbon deoiling at a flow rate of 5BV / h, and then electrolytic reduction and adjusted to V 3+ =2.0mol / L, H + = 3.0 mol / L is used repeatedly as a stripping agent;

[0066] Step 2, complex stripping to extract tungsten and molybdenum. Use 8% oxalic acid solution as stripping agent, and carry out 4-stage countercurrent stripping at 60°C with the extractant and stripping agent obtained in step 1 at a ratio of O / A=18:1. After stripping, obtain low-vanadium, tungsten, and molybdenum extractants and tungsten and molybdenum stripping solutions; the tungsten and molybdenum stripping solutions are subjected to aeration deoiling, SV650 resin deoiling, and activated carbon deoiling at a flow rate of 5BV / h, and then heated to 90°C for hydrolysis to precipitate tungsten and molybdenum. After solid-liquid separation, oxalic acid solution is obtained, which can be reused. Molybdenum oxide and tungsten oxide are obtained after drying and calcination of molybdic acid and tungstic acid;

[0067] Step 3, complex stripping to extract titanium. A mixed solution containing 3% H2O2 and 30% sulfuric acid is used as the stripping agent, and the extractant and stripping agent obtained in step 2 are subjected to two-stage countercurrent stripping at a temperature of 30°C according to a ratio of O / A=18:1. After the stripping is completed, low vanadium, tungsten, molybdenum, titanium extractant and titanium stripping solution are obtained; the titanium stripping solution is subjected to aeration deoiling, SV650 resin deoiling and activated carbon deoiling at a flow rate of 5BV / h, and then the temperature is raised to 90°C for hydrolysis and precipitation of titanium. Titanium metatitanic acid and dilute sulfuric acid are obtained through solid-liquid separation. The dilute sulfuric acid can be reused. Titanium oxide is obtained after the titanium metatitanic acid is dried and calcined;

[0068] Step 4, reductive pickling: The extractant obtained in step 3 and the sulfurous acid solution are subjected to two-stage countercurrent pickling at a temperature of 30°C according to a ratio of O / A=12:1. After the pickling is completed, the regenerated extractant and pickling solution are obtained, which can be reused after adding sulfur dioxide.

[0069] After impurities are removed through the above steps, the vanadium content in the P204 extractant is 0.010 g / L, the tungsten content is 0.017 g / L, the molybdenum content is 0.021 g / L, and the titanium content is 0.032 g / L after detection and treatment. The P204 extractant removes vanadium, tungsten, molybdenum, and titanium with a removal rate greater than 99.8%. The recovery rate of the P204 extractant is 98.8%, and the recovery rates of the valuable metals vanadium, tungsten, molybdenum, and titanium are greater than 99.0%.

[0070] Example 3

[0071] This embodiment discloses a method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant, comprising the following steps:

[0072] The vanadium content in the Cyanex272 extractant before testing was 1.2 g / L, the tungsten content was 3.1 g / L, the molybdenum content was 3.8 g / L, and the titanium content was 5.4 g / L.

[0073] Step 1: Reduction stripping to extract vanadium. 3+ =1.0mol / L, H + =4.0mol / L phosphoric acid solution was used as the stripping agent and Cyanex272 extractant according to the ratio of O / A=16:1, and 4-stage countercurrent stripping was carried out at a temperature of 50°C. After the stripping was completed, low-vanadium Cyanex272 extractant and vanadium stripping solution were obtained; the vanadium stripping solution was subjected to aeration deoiling, ADS600 resin deoiling and activated carbon deoiling at a flow rate of 4BV / h, and then electrolytic reduction and adjusted to V 3+ =1.0mol / L, H + =4.0mol / L is used repeatedly as stripping agent;

[0074] Step 2, complex stripping to extract tungsten and molybdenum. Use 6% oxalic acid solution as stripping agent, and carry out three-stage countercurrent stripping at 60°C with the extractant and stripping agent obtained in step 1 according to the ratio of O / A=16:1. After stripping, low vanadium, tungsten and molybdenum extractant and tungsten and molybdenum stripping solution are obtained; the tungsten and molybdenum stripping solution is subjected to aeration deoiling, ADS 600 resin deoiling and activated carbon deoiling at a flow rate of 4BV / h, and then heated to 98°C for hydrolysis and precipitation of tungsten and molybdenum. After solid-liquid separation, oxalic acid solution is obtained, which can be reused. Molybdenum oxide and tungsten oxide are obtained after drying and calcination of molybdic acid and tungstic acid;

[0075] Step 3, complex stripping to extract titanium. A mixed solution containing 4% H2O2 and 20% sulfuric acid is used as the stripping agent, and the extractant and stripping agent obtained in step 2 are subjected to three-stage countercurrent stripping at a temperature of 35°C according to a ratio of O / A=20:1. After the stripping is completed, low vanadium, tungsten, molybdenum, titanium extractant and titanium stripping solution are obtained; the titanium stripping solution is subjected to aeration deoiling, ADS 600 resin deoiling and activated carbon deoiling at a flow rate of 4BV / h, and then the temperature is raised to 98°C to hydrolyze and precipitate titanium, and titanic acid and dilute sulfuric acid are obtained by solid-liquid separation. The dilute sulfuric acid can be reused, and the titanic acid is dried and calcined to obtain titanium oxide;

[0076] Step 4, reductive pickling: The extractant obtained in step 3 and the sulfurous acid solution are subjected to two-stage countercurrent pickling at a temperature of 35°C according to a ratio of O / A=10:1. After the pickling is completed, the regenerated extractant and pickling solution are obtained, which can be reused after adding sulfur dioxide.

[0077] After impurities are removed through the above steps, the vanadium content in the Cyanex272 extractant is 0.0055 g / L, the tungsten content is 0.012 g / L, the molybdenum content is 0.018 g / L, and the titanium content is 0.021 g / L after detection and treatment. The Cyanex272 extractant removes vanadium, tungsten, molybdenum, and titanium with a removal rate greater than 99.4%. The recovery rate of the Cyanex272 extractant is 99.2%, and the recovery rates of the valuable metals vanadium, tungsten, molybdenum, and titanium are greater than 99.0%.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant, characterized in that: The following steps are involved: Step 1, reduction stripping to extract vanadium, using a reducing acid solution as a first stripping agent, mixing an organic phosphate extractant and the first stripping agent for countercurrent stripping, and obtaining a low-vanadium extractant and a vanadium stripping solution after stripping; Step 2: extracting tungsten and molybdenum by complex stripping, using oxalic acid solution as the second stripping agent, mixing the low-vanadium extractant obtained in step 1 with the second stripping agent for countercurrent stripping, and obtaining a low-vanadium, tungsten, and molybdenum extractant and a tungsten and molybdenum stripping solution after stripping; Step 3, complex stripping to extract titanium, using a mixed solution of hydrogen peroxide and dilute sulfuric acid as the third stripping agent, mixing the low-vanadium, tungsten, and molybdenum extractant obtained in step 2 and the third stripping agent for countercurrent stripping, and obtaining a low-vanadium, tungsten, molybdenum, and titanium extractant and a titanium stripping solution after stripping; Step 4, reductive pickling, mixing the low vanadium, tungsten, molybdenum, titanium extractant obtained in step 3 with the sulfurous acid solution for countercurrent pickling, and obtaining a regenerated extractant and a pickling solution after the pickling is completed.

2. The method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant according to claim 1, characterized in that: The organophosphate extractant in step 1 is one or more of P507, P204 and Cyanex272; And or, the vanadium content in the organic phosphate extractant in step 1 is 1-2 g / L, the tungsten content is 3-5 g / L, the molybdenum content is 3-5 g / L, and the titanium content is 5-8 g / L.

3. The method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant according to claim 1, characterized in that: The reducing acid solution in step 1 is one or more of sulfuric acid, hydrochloric acid, and phosphoric acid with a free hydrogen ion concentration of 1.0 to 5.0 mol / L, wherein V 3+ =0.5~2.0mol / L; And or, in step 1, the organic phosphate extractant and the first stripping agent are mixed according to the ratio O / A=(10-20):1 for countercurrent stripping, the stripping stage is 1-4, and the stripping temperature is 20-80°C.

4. The method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant according to claim 1, characterized in that: Step 1: The vanadium stripping solution after stripping is subjected to aeration deoiling, resin deoiling and activated carbon deoiling in sequence, and then electrolytic reduction and adjustment before being reused as a stripping agent.

5. The method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant according to claim 1, characterized in that: The concentration of the oxalic acid solution in step 2 is 3-8%; And or, step 2: mixing the low-vanadium extractant obtained in step 1 with the second stripping agent in a ratio of O / A=(10-20):1 for countercurrent stripping, the stripping stage is 1-5, and the stripping temperature is 40-60°C.

6. The method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant according to claim 1, characterized in that: Step 2: After the tungsten and molybdenum stripping solutions are subjected to aeration deoiling, resin deoiling and activated carbon deoiling in turn, the temperature is raised to 80-100°C to hydrolyze and precipitate tungsten and molybdenum, and molybdic acid, tungstic acid and oxalic acid solutions are obtained through solid-liquid separation. The oxalic acid solution can be reused. Molybdic acid and tungstic acid are dried and calcined to obtain molybdenum oxide and tungsten oxide.

7. The method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant according to claim 1, characterized in that: In step 3, the H2O2 concentration in the mixed solution of hydrogen peroxide and dilute sulfuric acid is 3-5%, and the sulfuric acid concentration is 20-40%; And or, step 3: the low vanadium, tungsten, molybdenum extractant obtained in step 2 and the third stripping agent are mixed according to the ratio O / A=(10-20):1 for countercurrent stripping, the stripping stage is 1-3, and the stripping temperature is 20-40°C.

8. The method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant according to claim 1, characterized in that: Step 3: After the titanium stripping solution is subjected to aeration deoiling, resin deoiling and activated carbon deoiling in sequence, the temperature is raised to 90-100° C. to hydrolyze the precipitated titanium, and titanic acid and dilute sulfuric acid are obtained through solid-liquid separation. The dilute sulfuric acid can be reused, and the titanic acid is dried and calcined to obtain titanium oxide.

9. The method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant according to claim 4, 6 or 8, characterized in that: The aeration gas in step 1, step 2 and step 3 is nitrogen or argon, the gas flow rate is 1.0-3.0 L / min, the aeration pressure is 3.5-4.5 MPa, and the oil removal flow rate is 100-300 L / h; And or, the resin in step 1, step 2 and step 3 is an oil-removing resin, and the oil-removing resin is one or more of SV232, SV650, D113, ADS-500, ADS-600 and ADS-277, and the oil removal flow rate is 2 to 5 BV; And or, the activated carbon in step 1, step 2 and step 3 is coconut shell activated carbon with a particle size of 4 to 8 mm, an iodine value of 800 to 1200, and an oil removal flow rate of 2 to 5 BV.

10. The method for deeply reducing vanadium, tungsten, molybdenum and titanium in an organic phosphate extractant according to claim 1, characterized in that: Step 4: The low vanadium, tungsten, molybdenum, titanium extractant obtained in step 3 and the sulfurous acid solution are mixed according to the ratio O / A=(10-20):1 for countercurrent pickling, the pickling level is 1-3 levels, and the pickling temperature is 20-40°C; And or, step 4 is to add sulfur dioxide to the pickling solution, which can be reused.

Images