阅读说明：本技术 一种从钒渣钠化焙烧水浸出液中分离提取钒铬的方法 (Method for separating and extracting vanadium and chromium from vanadium slag sodium salt roasting water leachate ) 是由 王明玉 王学文 胡斌 张长达 廖志琴 赵士杰 于 2019-09-02 设计创作，主要内容包括：本发明公开了一种从钒渣钠化焙烧水浸出液中分离提取钒铬的方法,向钒渣钠化焙烧水浸出液中加入铵盐,并将溶液体系的pH控制在pH7.5～9.5,搅拌反应,然后固液分离得偏钒酸铵晶体和滤液A；将有机相B与滤液A进行萃取,得萃余液A1和负载有机相B1；负载有机相B1采用氢氧化钠溶液进行反萃取,得到反萃液A2；萃余液A1循环利用；向反萃液A2中加入沉钒剂并室温球磨,过滤得含钒滤渣C1和含铬滤液A3；向含钒滤渣C1加入萃余液A1,然后球磨,过滤得到滤渣C2和含钒滤液A4；滤渣C2煅烧后继续作为沉钒试剂使用,含钒滤液A4采用铵盐沉钒法分离回收其中的钒,含铬滤液A3除杂后蒸发结晶获得铬酸钠产品。本发明能实现钒铬的分离回收、钠元素及提钒铬后液的循环利用等优点。(The invention discloses a method for separating and extracting vanadium and chromium from a vanadium slag sodium salt roasting water extract, which comprises the steps of adding ammonium salt into the vanadium slag sodium salt roasting water extract, controlling the pH value of a solution system to be 7.5-9.5, stirring for reaction, and then carrying out solid-liquid separation to obtain ammonium metavanadate crystals and a filtrate A; extracting the organic phase B and the filtrate A to obtain raffinate A1 and a loaded organic phase B1; carrying out back extraction on the loaded organic phase B1 by using a sodium hydroxide solution to obtain a back extraction solution A2; recycling raffinate A1; adding a vanadium precipitation agent into the back extraction solution A2, ball-milling at room temperature, and filtering to obtain vanadium-containing filter residue C1 and chromium-containing filtrate A3; adding raffinate A1 into vanadium-containing filter residue C1, then carrying out ball milling, and filtering to obtain filter residue C2 and vanadium-containing filtrate A4; calcining the filter residue C2, and then continuously using the filter residue C2 as a vanadium precipitation reagent, separating and recovering vanadium in the vanadium-containing filtrate A4 by adopting an ammonium salt vanadium precipitation method, and removing impurities from the chromium-containing filtrate A3, and then evaporating and crystallizing to obtain a sodium chromate product. The invention can realize the separation and recovery of vanadium and chromium, the recycling of sodium element and the solution after vanadium and chromium extraction, and the like.)

1. A method for separating and extracting vanadium and chromium from a vanadium slag sodium salt roasting water leachate is characterized by comprising the following steps:

step (1): adding ammonium salt into the sodium salt roasting water leachate of the vanadium slag, controlling the pH value of a solution system to be 7.5-9.5, stirring for reaction, and then carrying out solid-liquid separation to obtain ammonium metavanadate crystals and a filtrate A;

step (2): extracting an organic phase B containing an extracting agent with a structural formula 1 with a filtrate A to obtain raffinate A1 and a loaded organic phase B1; carrying out back extraction on the loaded organic phase B1 by using a sodium hydroxide solution to obtain a back extraction solution A2, and returning the back extracted organic phase B2 to the extraction process for reuse after transformation; raffinate A1 is divided into two parts, namely A1-1 and A1-2, wherein the A1-1 is used for leaching the filter residue C1 in the step (3), the A1-2 is frozen and crystallized to separate out sodium carbonate or is introduced with carbon dioxide to crystallize and separate out sodium bicarbonate, a crystallized product returns to the vanadium slag sodium roasting process, and a crystallized liquid returns to the vanadium slag sodium roasting material leaching process;

said R₁～R₃Independently is C₈～C₁₂A straight chain alkyl group of (a); said R₄Is CH₃(ii) a A-is CO₃ ^2-Or HCO₃ ^-；

And (3): adding a vanadium precipitation agent into the back extraction solution A2, ball-milling at room temperature, and filtering to obtain vanadium-containing filter residue C1 and chromium-containing filtrate A3;

adding vanadium-containing filter residue C1 into raffinate A1-1, then carrying out ball milling, and filtering to obtain filter residue C2 and vanadium-containing filtrate A4;

calcining the filter residue C2, and then continuously using the filter residue C2 as a vanadium precipitation reagent, separating and recovering vanadium in the vanadium-containing filtrate A4 by adopting an ammonium salt vanadium precipitation method, and removing impurities from the chromium-containing filtrate A3, and then evaporating and crystallizing to obtain a sodium chromate product.

2. The method for separating and extracting vanadium and chromium from the sodium roasting water leachate of vanadium slag as claimed in claim 1, wherein the adding ammonium salt refers to adding at least one of ammonium carbonate, ammonium bicarbonate and ammonia water; the amount of ammonium salt added is NH₃1 to 0.3 times of the mol ratio of the component (V).

3. The method for separating and extracting vanadium and chromium from the sodium roasting water leachate of vanadium slag as claimed in claim 1, wherein in the step (1), the pH of the solution system is controlled by carbon dioxide or ammonia water;

the stirring reaction is carried out at the temperature of 20-60 ℃ for 0.5-3 h;

and calcining the obtained ammonium metavanadate to obtain vanadium pentoxide.

4. The method for separating and extracting vanadium and chromium from the sodium roasting water leachate of vanadium slag as claimed in claim 1, wherein in the step (2), the organic phase B further comprises a diluent and an extraction aid with a structural formula of formula 2;

R₅-OH

formula 2

Said R₅Is C₈～C₁₃A straight or branched chain alkyl group of (1);

the diluent is one of sulfonated kerosene, No. 200 solvent oil and aviation kerosene.

5. The method for separating and extracting vanadium and chromium from the sodium roasting water leachate of vanadium slag as claimed in claim 4, wherein in the organic phase B, the volume percentage concentration of the extracting agent is 5-40%; the volume percentage concentration of the extraction aid is 5-20%.

6. The method for separating and extracting vanadium and chromium from the sodium roasting water leachate of vanadium slag as claimed in claim 5, wherein in the step (2), the O/A in the extraction process is 1:10-5: 1; the extraction mode is countercurrent extraction;

the concentration of the sodium hydroxide solution in the back extraction process is 1-5 mol/L; the O/A is 2:1-10:1, and the extraction mode is counter-current back extraction;

the organic phase transformation refers to transformation treatment by adopting bicarbonate solution, wherein the bicarbonate is at least one of sodium bicarbonate, ammonium bicarbonate and potassium bicarbonate.

7. The method for separating and extracting vanadium and chromium from the sodium roasting water leachate of vanadium slag as claimed in claim 1, wherein in the step (3), the vanadium precipitation agent is at least one of calcium oxide and calcium hydroxide; the vanadium precipitation agent is added according to the Ca/V molar ratio of 0.5-1.5: 1.

8. The method for separating and extracting vanadium and chromium from the vanadium slag sodium roasting water leachate as claimed in claim 1, wherein in the step (3), the vanadium-containing filter residue C1 is added into raffinate A1-1 according to the solid-to-liquid ratio of 1:2-10g/ml, then ball milling is carried out at 20-100 ℃ for 20-60min, and the filter residue C2 and the vanadium-containing filtrate A4 are obtained by filtering.

9. The method for separating and extracting vanadium and chromium from the sodium roasting water leachate of vanadium slag as claimed in claim 1, wherein the step of removing impurities from the filtrate A3 is to add sodium carbonate into the solution according to the Ca/Na molar ratio of 1:2-4, stir the solution for 5-60min at 20-100 ℃, and then filter and separate the solution.

Technical Field

The invention belongs to the field of metallurgical separation and circulating metallurgy, and particularly relates to a method for separating and extracting vanadium and chromium from a vanadium slag sodium roasting water extract.

Background

The vanadium slag is a main industrial raw material for extracting vanadium, and the vanadium slag in China mainly comes from the pyrometallurgical smelting process of vanadium-titanium magnetite. The vanadium titano-magnetite is a composite ore formed by symbiosis of various valuable elements such as iron, vanadium, titanium, chromium and the like. Because the properties of vanadium and chromium are similar, the trend of vanadium and chromium in the pyrometallurgical process is basically consistent, the vanadium slag obtained by pyrometallurgical process is actually a chromium-containing vanadium slag, and the vanadium content in the slag is usually far higher than that of chromium, so the slag is generally called vanadium slag.

The most widely used industrialization of vanadium extraction from vanadium slag is the sodium roasting-water leaching process. Vanadium and chromium enter the solution in the forms of V (V) and Cr (VI) respectively in the water leaching process of the sodium-modified roasting material, and then ammonium polyvanadate is crystallized and separated out by adopting an acidic ammonium salt vanadium precipitation method. The process is simple, but has a series of problems: (1) solutions with high concentrations of vanadium and chromium cannot be treated. The existing acidic ammonium salt vanadium precipitation process requires that the concentration of vanadium in a leaching solution is controlled to be 20-30 g/L, and the chromium content is not more than 1 g/L. (2) Chromium cannot be recovered and a large amount of hazardous solid waste is produced. The mother liquor obtained after the acid ammonium salt is subjected to vanadium precipitation is a solution containing chromium and a small amount of vanadium. The mother liquor is generally treated by a reduction-neutralization process: v (V) and Cr (VI) in the solution are reduced firstly, and then neutralized and precipitated to obtain vanadium-chromium reducing slag, and the vanadium-chromium reducing slag has complex components and high recycling difficulty, and belongs to dangerous solid waste. (3) The solution after vanadium precipitation can not be reused. The solution obtained after vanadium slag water leachate is crystallized to precipitate vanadium and is subjected to reduction-neutralization vanadium and chromium removal is sulfate solution containing sodium and ammonium, and the sulfate solution cannot be recycled. The existing treatment mode is to directly evaporate the solutions, so that the cost is huge, and the evaporation product is a sodium sulfate/ammonium sulfate mixed crystal containing a small amount of vanadium and chromium, is dangerous and solid waste, is not available, and is difficult to store.

In Fahrenheit et al (chemical metallurgy, 2 nd 1980), primary ammonium N1923 is adopted to separate and extract vanadium and chromium in leachate: vanadium is first selectively extracted and then chromium is extracted from the raffinate. Although the primary ammonium N1923 step-by-step extraction can realize the separation and recovery of vanadium and chromium, the vanadium and chromium are separated and extracted from the leachate by the two-step extraction method, the cost is high, the economic applicability is unavailable, and a large amount of sodium sulfate-containing raffinate is generated after the vanadium and chromium are separated and extracted from the primary ammonium N1923, and the raffinate cannot be recycled, so that the treatment cost is high, and the treatment difficulty is high. Chinese patent 201711079106.5 firstly adopts a calcium salt precipitation method to selectively and directly precipitate all vanadium in the sodium salt roasting water leaching solution of the vanadium slag, then uses a carbonate solution to leach vanadium in the precipitate and recovers the vanadium, and the solution after vanadium precipitation can realize the recovery of chromium and sodium carbonate by adopting an electrodialysis-crystallization method; however, the method has complex process and large alkali consumption. Chinese patent 200610089232.4 discloses a process for separating vanadium and chromium by primary and secondary compound amine extraction, which comprises selectively extracting vanadium with primary and secondary compound amine to leave chromium in water phase, recovering chromium by reduction precipitation method, and recovering vanadium by ammonium salt precipitation method; the method can realize the separation and recovery of vanadium and chromium, but has the disadvantages of large alkali consumption, incapability of recycling waste water, difficult control of the extraction process and high cost of the extractant.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method for separating and extracting vanadium and chromium from a sodium roasting water extract of vanadium slag, which has the characteristics of simple process, low cost, recycling of sodium element and the solution after vanadium and chromium extraction, and capability of simultaneously separating and extracting vanadium and chromium.

The vanadium slag sodium salt roasting water leachate is a complex sodium salt solution containing V (V) and Cr (VI), and the existing treatment process cannot realize the high-efficiency separation and recovery of vanadium and chromium and the recycling of sodium elements and wastewater, so the invention provides the following technical scheme:

a method for separating and extracting vanadium and chromium from a vanadium slag sodium salt roasting water leachate comprises the following steps:

step (1): adding ammonium salt into the sodium salt roasting water leachate of the vanadium slag, controlling the pH value of a solution system to be 7.5-9.5, stirring for reaction, and then carrying out solid-liquid separation to obtain ammonium metavanadate crystals and a filtrate A;

step (2): extracting an organic phase B containing an extracting agent with a structural formula 1 with a filtrate A to obtain raffinate A1 and a loaded organic phase B1; carrying out back extraction on the loaded organic phase B1 by using a sodium hydroxide solution to obtain a back extraction solution A2, and returning the back extracted organic phase B2 to the extraction process for reuse after transformation; raffinate A1 is divided into two parts, namely A1-1 and A1-2, wherein the A1-1 is used for leaching the filter residue C1 in the step (3), the A1-2 is frozen and crystallized to separate out sodium carbonate or is introduced with carbon dioxide to crystallize and separate out sodium bicarbonate, a crystallized product returns to the vanadium slag sodium roasting process, and a crystallized liquid returns to the vanadium slag sodium roasting material leaching process;

said R₁～R₃Independently is C₈～C₁₂A straight chain alkyl group of (a); said R₄Is CH₃(ii) a A-is CO₃ ^2-Or HCO₃ ^-；

And (3): adding a vanadium precipitation agent into the back extraction solution A2, ball-milling at room temperature, and filtering to obtain vanadium-containing filter residue C1 and chromium-containing filtrate A3;

adding vanadium-containing filter residue C1 into raffinate A1-1, then carrying out ball milling, and filtering to obtain filter residue C2 and vanadium-containing filtrate A4;

calcining the filter residue C2, and then continuously using the filter residue C2 as a vanadium precipitation reagent, separating and recovering vanadium in the vanadium-containing filtrate A4 by adopting an ammonium salt vanadium precipitation method, and removing impurities from the chromium-containing filtrate A3, and then evaporating and crystallizing to obtain a sodium chromate product.

The technical scheme of the invention innovatively provides an innovative process line for ammonium salt pre-extraction of vanadium, synchronous extraction of vanadium and chromium and selective vanadium precipitation, and innovatively performs coupling control on each processing condition of each process line, so that high-efficiency separation of vanadium and chromium can be innovatively realized, recycling of sodium element can be realized, and generation of high-risk solid waste and high-load wastewater treatment can be avoided.

The main innovation of the method is a targeted brand-new treatment process thought provided for the treatment difficulty of the sodium roasting water extract, and the method further couples and controls the conditions of the steps such as vanadium pre-extraction in the step (1), vanadium-chromium synchronous extraction in the step (2), sodium recovery and the like based on the innovative process thought.

Preferably, in the step (1), the adding of the ammonium salt refers to adding at least one of ammonium carbonate, ammonium bicarbonate and ammonia water; the amount of ammonium salt added is NH₃1 to 0.3 times of the mol ratio of the component (V).

Preferably, step (1): the pH of the solution system is controlled by carbon dioxide or ammonia.

Preferably, step (1): the stirring reaction is carried out at the temperature of 20-60 ℃ for 0.5-3 h.

Based on the innovative processing idea of the invention, part of high-purity vanadium is obtained in advance under the conditions, so that the alkali consumption is reduced for the subsequent separation and extraction of vanadium and chromium, and the vanadium and chromium synchronous extraction and sodium recovery in the step (2) are facilitated.

Preferably, the ammonium metavanadate prepared in the step (1) is calcined to obtain qualified vanadium pentoxide.

Based on the vanadium pre-extraction process in the step (1), the A-anionic extractant is further matched, so that vanadium and chromium can be innovatively extracted synchronously, and the recovery and the cyclic utilization of sodium elements in the sodium treatment leachate can be unexpectedly realized.

Preferably, in the step (2), the organic phase B further comprises a diluent and an extraction aid having a structural formula of formula 2;

R₅-OH

formula 2

Said R₅Is C₈～C₁₃The straight-chain or branched alkyl group of (2) may be, for example, octane-2-yl.

Preferably, the diluent is one of sulfonated kerosene, 200 # solvent oil and aviation kerosene.

Preferably, in the organic phase B, the volume percentage concentration of the extracting agent is 5-40%; the volume percentage concentration of the extraction aid is 5-20%, and the rest is diluent.

Preferably, in the step (2), the O/A ratio in the extraction process is 1:10-5: 1; the extraction mode is countercurrent extraction.

Preferably, the concentration of the sodium hydroxide solution in the back extraction process is 1-5 mol/L; the O/A ratio is 2:1-10:1, and the extraction mode is counter-current back extraction.

Preferably, the organic phase transformation refers to transformation treatment by using bicarbonate solution, wherein the bicarbonate is at least one of sodium bicarbonate, ammonium bicarbonate and potassium bicarbonate.

And (3): adding selective vanadium precipitation agent into the back extraction solution A2, ball-milling at room temperature for 20-60min, and filtering to obtain vanadium-containing filter residue C1 and chromium-containing filtrate A3. Adding vanadium-containing filter residue C1 into raffinate A1-1 according to the solid-to-liquid ratio of 1:2-10g/ml, then carrying out ball milling at 20-100 ℃ for 20-60min, and filtering to obtain filter residue C2 and vanadium-containing filtrate A4. Calcining the filter residue C2, and then continuously using the filter residue C2 as a selective vanadium precipitation reagent, separating and recovering vanadium in the vanadium-containing filtrate A4 by adopting an ammonium salt vanadium precipitation method, and removing impurities from the chromium-containing filtrate A3, and then evaporating and crystallizing to obtain a sodium chromate product.

The invention relates to a method for separating and extracting vanadium and chromium from a sodium salt roasting water leachate of vanadium slag, wherein a vanadium precipitation agent is at least one of calcium oxide and calcium hydroxide; the vanadium precipitation agent is added according to the Ca/V molar ratio of 0.5-1.5: 1.

The invention relates to a method for separating and extracting vanadium and chromium from a sodium salt roasting water leachate of vanadium slag, wherein the step of removing impurities from a filtrate A3 is to add sodium carbonate into the solution according to the Ca/Na molar ratio of 1:2-4, stir the solution for 5-60min at the temperature of 20-100 ℃, and then filter and separate the solution.

The invention discloses a preferable method for separating and extracting vanadium and chromium from a vanadium slag sodium roasting water leachate, which comprises the following steps:

step (1): adding ammonium salt into the sodium salt roasting water leachate of the vanadium slag, adding carbon dioxide or ammonia water to control the pH value of the solution to be 7.5-9.5, stirring and reacting for 0.5-3 h at the temperature of 20-60 ℃, then carrying out solid-liquid separation to obtain ammonium metavanadate crystals and a filtrate A, and calcining the ammonium metavanadate to obtain qualified vanadium pentoxide.

Step (2): mixing an organic phase B containing an extracting agent with the filtrate A, and performing 3-14-grade countercurrent extraction under the condition that the flow ratio (organic phase to aqueous phase) is 1:10-5:1 to obtain raffinate A1 and a loaded organic phase B1; carrying out 4-15-stage counter-current back extraction on the loaded organic phase B1 by adopting 1-5mol/L sodium hydroxide solution under the condition of a flow ratio of 2:1-10:1 to obtain a back extraction solution A2, and returning the back extraction solution B2 after back extraction to the extraction process for reuse; raffinate A1 is divided into two parts, namely A1-1 and A1-2, wherein the A1-1 is used for leaching the filter residue C1 in the step (3), the A1-2 is frozen and crystallized to separate out sodium carbonate or is introduced with carbon dioxide to crystallize and separate out sodium bicarbonate, a crystallized product returns to the vanadium slag sodium roasting process, and a crystallized liquid returns to the vanadium slag sodium roasting material leaching process;

and (3): adding selective vanadium precipitation agent into the back extraction solution A2, ball-milling at room temperature for 20-60min, and filtering to obtain vanadium-containing filter residue C1 and chromium-containing filtrate A3. Adding vanadium-containing filter residue C1 into raffinate A1-1 according to the solid-to-liquid ratio of 1:2-10g/ml, then carrying out ball milling at 20-100 ℃ for 20-60min, and filtering to obtain filter residue C2 and vanadium-containing filtrate A4. Calcining the filter residue C2, and then continuously using the filter residue C2 as a selective vanadium precipitation reagent, separating and recovering vanadium in the vanadium-containing filtrate A4 by adopting an ammonium salt vanadium precipitation method, and removing impurities from the chromium-containing filtrate A3, and then evaporating and crystallizing to obtain a sodium chromate product.

Compared with the prior art, the invention has the following advantages and effects:

the properties of V (V) and Cr (VI) in the solution are similar, so that the separation and recovery of V (V) and Cr (VI) in the solution are always difficult in the separation field. In the previous research on the separation and extraction of V (V) and Cr (VI) in the solution, all vanadium is firstly selectively separated, and then chromium is separated and extracted. Aiming at the problems existing in the separation and extraction of vanadium and chromium from the sodium salt roasting water leachate of vanadium slag at present, the invention innovatively provides a method for separating and extracting vanadium and chromium from the sodium salt roasting water leachate of vanadium slag, which comprises the following steps: firstly, part of vanadium is selectively separated out in the form of pure ammonium metavanadate, and then the residual vanadium and all chromium are co-extracted by a carbonate extractant, so that the separation of vanadium and chromium from sodium elements and the enrichment of vanadium and chromium are realized. The leachate after separating and enriching the vanadium and the chromium is changed into a single sodium carbonate solution system without ammonium or containing trace ammonium, thereby creating a key condition for the recycling of the sodium element. The high-concentration vanadium-chromium-containing solution obtained by back-extracting the vanadium-chromium-loaded organic phase realizes the separation and recovery of vanadium and chromium by a chemical precipitation method. The method has the advantages of simple process, low cost, capability of being applied to the solution containing high-concentration vanadium and chromium, capability of realizing the separation and recovery of vanadium and chromium, the recycling of sodium element and the zero discharge of wastewater, suitability for industrial application and the like.

Detailed Description

The following examples are intended to illustrate the invention without further limiting its scope.

The extractant of the invention can be commercially availableThe extractant with the structure is obtained by transforming carbonate and/or bicarbonate solution.

Example 1

Taking 4L vanadium slag sodium salt roasting water leachate containing V30 g/L and Cr 1.1g/L, introducing carbon dioxide to adjust the pH value of the leachate to 8.5, and then regulating the pH value according to NH₃Adding ammonium carbonate with the molar ratio of 1 time of that of the vanadium to the vanadium, stirring the mixture for 3 hours at room temperature, and then filtering and separating the mixture to obtain ammonium meta-acid crystals and filtrate A, wherein the recovery rate of the vanadium is 78%; calcining ammonium metavanadate at 500 ℃ for 2h to obtain a vanadium pentoxide product containing 99.3 percent of vanadium, wherein the content of Cr is 0.03 percent.

Filtrate A was mixed with an extractant composed of 40% methyl trialkyl (R in the formula 1)₁～R₃Is C₈～C₁₀Linear alkyl radical of (2), R₄Is CH₃，A^-Is CO₃ ^2-) Organic phases of + 20% of secondary octanol and 40% of sulfonated kerosene (volume percentage) are mixed, and then 3-stage countercurrent extraction is carried out under the condition that the flow ratio is 1:10, so as to obtain raffinate A1 and a loaded organic phase B1. Part of raffinate A1 is used for leaching in the subsequent steps, the rest is frozen and crystallized to separate out sodium carbonate, the sodium carbonate returns to the vanadium slag roasting process, and the crystallized liquid returns to the vanadium slag sodium-modified material leaching process, so that leaching of the vanadium slag sodium-modified roasting water is realizedAnd (5) recycling the liquid. After the loaded organic phase B1 is washed, 4-stage countercurrent back extraction is carried out by adopting 5mol/L sodium hydroxide solution, the back extraction flow ratio is 2:1, and a vanadium-chromium-containing back extraction solution A2 and a back extraction organic phase B2 are obtained; the back extraction organic phase is transformed by sodium bicarbonate and then returns to the extraction process, and the total extraction rate of vanadium is 99.8 percent and the extraction rate of chromium is 99.3 percent in the whole extraction and back extraction process.

Adding calcium hydroxide into the stripping solution A2 according to the Ca/V molar ratio of 0.5:1, carrying out warm ball milling for 30min, and filtering to obtain vanadium-containing filter residue C1 and chromium-containing filtrate A3. Adding sodium carbonate into the chromium-containing filtrate A3 according to the Ca/Na molar ratio of 1:2, stirring for 60min at room temperature, filtering, separating, evaporating and crystallizing the filtrate to obtain a sodium chromate product with the purity of 99.5 percent. Adding vanadium-containing filter residue C1 into raffinate A1 according to the solid-to-liquid ratio of 1:2g/ml, carrying out ball milling at 100 ℃ for 20min, filtering to obtain vanadium-containing filtrate A4, and separating and recovering vanadium in the vanadium-containing filtrate A4 by adopting an acidic ammonium salt vanadium precipitation method to obtain qualified ammonium polyvanadate.

Example 2

Taking 3L vanadium slag sodium salt roasting water leachate containing V30 g/L and Cr 13g/L, introducing carbon dioxide to adjust the pH value of the leachate to 7.5, and then adding NH₃Adding ammonium bicarbonate with the molar ratio of 0.8 times of V into the solution, stirring the solution at 60 ℃ for 0.5h, adding ammonia water during the stirring to control the pH value of the solution to be about 8.0, and then filtering and separating the solution to obtain ammonium metaphosphate crystals and a filtrate A, wherein the recovery rate of vanadium is 61%; calcining ammonium metavanadate at 500 ℃ for 2h to obtain a vanadium pentoxide product containing 99.2 percent of vanadium, wherein the content of Cr is 0.05 percent.

Mixing the filtrate A with 5% methyl trioctyl extractant (R in formula 1)₁～R₃Is n-octyl; r₄Is CH₃；A^-Is CO₃ ^2-) Mixing organic phases of 10 percent of secondary octanol and 85 percent of aviation kerosene (volume percentage), and then carrying out 8-stage countercurrent extraction under the condition of a flow ratio of 5:1 to obtain raffinate A1 and a loaded organic phase B1. After the loaded organic phase B1 is washed, 6-stage countercurrent back extraction is carried out by adopting 5mol/L sodium hydroxide solution, the back extraction flow ratio is 10:1, and a vanadium-chromium-containing back extraction solution A2 and a back extraction organic phase B2 are obtained; the back extraction organic phase is transformed by potassium bicarbonate and then returns to the extraction process, and the total extraction rate of vanadium is 99.7 percent and the extraction rate of chromium is 99.8 percent in the whole extraction and back extraction process.

Adding calcium oxide into the vanadium-chromium-containing strip liquor A2 according to the Ca/V molar ratio of 1.5:1, carrying out warm ball milling for 60min, and filtering to obtain vanadium-containing filter residue C1 and chromium-containing filtrate A3. Adding sodium carbonate into the chromium-containing filtrate A3 according to the Ca/Na molar ratio of 1:4, stirring for 40min at room temperature, filtering, separating, evaporating and crystallizing the filtrate to obtain a sodium chromate product with the purity of 99.6 percent. Adding vanadium-containing filter residue C1 into raffinate A1 according to the solid-to-liquid ratio of 1:5g/ml, carrying out ball milling at 20 ℃ for 60min, filtering to obtain vanadium-containing filtrate A4, and separating and recovering vanadium in the vanadium-containing filtrate A4 by adopting an acidic ammonium salt vanadium precipitation method to obtain qualified ammonium polyvanadate.

Example 3

Taking 2L vanadium slag sodium salt roasting water leachate containing V80 g/L and Cr 40g/L, and then carrying out reaction according to NH₃Adding liquid ammonia with the mol ratio of 0.6 times of that of the vanadium, introducing carbon dioxide to adjust the pH value of the leachate to 9.5, stirring for 2 hours at room temperature, and then filtering and separating to obtain ammonium meta-acid crystals and filtrate A, wherein the recovery rate of the vanadium is 49%; calcining ammonium metavanadate at 500 ℃ for 2h to obtain a vanadium pentoxide product containing 99.1 percent of vanadium, wherein the content of Cr is 0.07 percent.

Filtrate A was mixed with an extractant consisting of 10% methyltrisononyl (R in the formula 1)₁～R₃Is n-nonyl, R₄Is CH₃；A^-Is CO₃ ^2-) + 10% tridecanol + 80% mineral spirit 200 (vol.%) and then a 14 stage countercurrent extraction at a 1:4 flow ratio to yield raffinate A1 and loaded organic phase B1. After the loaded organic phase B1 is washed, 8-stage countercurrent back extraction is carried out by adopting 3mol/L sodium hydroxide solution, the back extraction flow ratio is 4:1, and a vanadium-chromium-containing back extraction solution A2 and a back extraction organic phase B2 are obtained; and the back extraction organic phase B2 is transformed by ammonium bicarbonate and then is returned for extraction, and the total extraction rate of vanadium is 99.5 percent and the extraction rate of chromium is 99.6 percent in the whole extraction and back extraction process.

Adding calcium hydroxide into the stripping solution according to the Ca/V molar ratio of 0.8:1, carrying out warm ball milling for 40min, and filtering to obtain vanadium-containing filter residue C1 and chromium-containing filtrate A3. Adding sodium carbonate into the chromium-containing filtrate according to the Ca/Na molar ratio of 1:3, stirring for 5min at 100 ℃, filtering, separating, evaporating and crystallizing the filtrate to obtain a sodium chromate product with the purity of 99.3 percent. Adding vanadium-containing filter residue C1 into raffinate A1 according to the solid-to-liquid ratio of 1:4g/ml, ball-milling at room temperature for 30min, filtering to obtain vanadium-containing filtrate A4, and separating and recovering vanadium in the vanadium-containing filtrate A4 by adopting an acidic ammonium salt vanadium precipitation method to obtain qualified ammonium polyvanadate.

Example 4

Taking 8L vanadium slag sodium salt roasting water leachate containing V15g/L and Cr 40g/L, introducing carbon dioxide to adjust the pH value of the leachate to 8.5, and then regulating the pH value according to NH₃Adding ammonium carbonate with the molar ratio of 0.3 times of that of the vanadium, stirring for 3 hours at 40 ℃, and filtering and separating to obtain ammonium meta-acid crystals and filtrate A, wherein the recovery rate of the vanadium is 32%; calcining ammonium metavanadate at 550 ℃ for 1.5h to obtain a vanadium pentoxide product containing 99.0 percent of vanadium, wherein the content of Cr is 0.09 percent.

Filtrate A was mixed with 20% methyl trialkyl extractant (R in formula 1)₁～R₃Is C₈～C₁₀Linear alkyl radical of (2), R₄Is methyl, A^-Is HCO₃ ^-) Mixing organic phases of 20 percent of secondary octanol and 60 percent of aviation kerosene (volume percentage), and then carrying out 10-grade countercurrent extraction under the condition of a flow ratio of 1:3 to obtain raffinate A1 and a loaded organic phase B1. After the loaded organic phase B1 is washed, 15-stage countercurrent back extraction is carried out by adopting 2mol/L sodium hydroxide solution, the back extraction flow ratio is 5:1, and a vanadium-chromium-containing back extraction solution A2 and a back extraction organic phase B2 are obtained; and the back extraction organic phase B2 is transformed by ammonium bicarbonate and then is returned for extraction, and the total extraction rate of vanadium is 99.5 percent and the extraction rate of chromium is 99.8 percent in the whole extraction and back extraction process.

Adding calcium hydroxide into the stripping solution according to the Ca/V molar ratio of 1:1, carrying out warm ball milling for 20min, and filtering to obtain vanadium-containing filter residue C1 and chromium-containing filtrate A3. Adding sodium carbonate into the chromium-containing filtrate according to the Ca/Na molar ratio of 1:3, stirring for 30min at 80 ℃, filtering, separating, evaporating and crystallizing the filtrate to obtain a sodium chromate product with the purity of 99.5 percent. Adding vanadium-containing filter residue C1 into raffinate A1 according to the solid-to-liquid ratio of 1:3g/ml, carrying out ball milling at 60 ℃ for 40min, filtering to obtain vanadium-containing filtrate A4, and separating and recovering vanadium in the vanadium-containing filtrate A4 by adopting an acidic ammonium salt vanadium precipitation method to obtain qualified ammonium polyvanadate.

Example 5

Compared with the example 4, the difference is that the roasted material of the sodium salt of the vanadium slag containing V15% and Cr 0.3% is added into the raffinate A1 (raffinate A1 is firstly frozen and crystallized to recover sodium carbonate) in the example 4 according to the solid-to-liquid ratio of 1:5g/L, stirred and leached for 5 hours at 80 ℃, and the solid-liquid separation is carried out, the leaching rate of the vanadium is 94.3%, and the leaching rate of the chromium is 64.8%.

Comparative example 1

Adding water into a vanadium slag sodium salt roasting material containing V15% and Cr 0.3% according to a solid-to-liquid ratio of 1:5g/L, stirring and leaching at 80 ℃ for 5 hours, and carrying out solid-liquid separation to obtain a leaching solution and leaching slag. The leaching rate of vanadium was 89.8%, and the leaching rate of chromium was 59.7%. And after removing impurities from the leaching solution, adding sulfuric acid and ammonium sulfate to carry out acid ammonium salt vanadium precipitation, and filtering to obtain an ammonium polyvanadate product and a vanadium precipitation solution.

Adding vanadium-precipitation solution at 80 ℃ for stirring and leaching for 5h according to the solid-to-liquid ratio of 1:5g/L, taking the vanadium slag sodium salt roasting material containing V15% and Cr 0.3%, and carrying out solid-liquid separation, wherein the leaching rate of vanadium is 68.2%, and the leaching rate of chromium is 38.9%.

Example 5 and comparative example 1 show that the solution (raffinate a1) after vanadium and chromium extraction recovered by the treatment process of the invention can be recycled, so that the recycling of resources is realized, and the leaching rate of vanadium and chromium can be unexpectedly improved compared with the original direct water leaching process.

Example 6

Taking 4L vanadium slag sodium salt roasting water leachate containing V30 g/L and Cr 1.1g/L, introducing carbon dioxide to adjust the pH value of the leachate to 8.5, and then regulating the pH value according to NH₃Adding ammonium carbonate with the molar ratio of 1 time of that of the vanadium to the vanadium, stirring the mixture for 3 hours at room temperature, and then filtering and separating the mixture to obtain ammonium meta-acid crystals and filtrate A, wherein the recovery rate of the vanadium is 78%; calcining ammonium metavanadate at 500 ℃ for 2h to obtain a vanadium pentoxide product containing 99.3 percent of vanadium, wherein the content of Cr is 0.03 percent.

Filtrate A was mixed with a 10% methyl trialkyl extractant (R in the formula 1)₁～R₃Is C₈～C₁₀Linear alkyl radical of (2), R₄Is methyl, A^-Is CO₃ ^2-) Mixing organic phases of + 5% of secondary octanol and 85% of sulfonated kerosene (volume percentage), and then carrying out 5-stage countercurrent extraction under the condition that the flow ratio is 1:5 to obtain raffinate A1 and a loaded organic phase B1.

After the loaded organic phase B1 is washed, 4-stage countercurrent back extraction is carried out by adopting 5mol/L sodium hydroxide solution, the back extraction flow ratio is 2:1, and a vanadium-chromium-containing back extraction solution A2 and a back extraction organic phase B2 are obtained; and the back extraction organic phase is transformed by sodium bicarbonate and then returns to the extraction process, the total extraction rate of vanadium is 99.7 percent, the extraction rate of chromium is 99.4 percent, and the consumption of sodium hydroxide is 0.4 time of the molar ratio of Na/(V + Cr) in the sodium roasting water extract of the vanadium slag in the whole extraction and back extraction processes.

Comparative example 2

Compared with the example 6, the difference is that the vanadium pre-extraction treatment is not carried out, and the specific steps are as follows:

taking 4L vanadium slag sodium roasting water leachate containing V30 g/L and Cr 1.1g/L, introducing carbon dioxide to adjust the pH value of the leachate to 8.5, and mixing the solution with 10% methyl trialkyl extractant (in formula 1, R is₁～R₃Is C₈～C₁₀Linear alkyl radical of (2), R₄Is methyl, A^-Is CO₃ ^2-) Mixing organic phases of + 5% of secondary octanol and 85% of sulfonated kerosene (volume percentage), and then carrying out 10-stage countercurrent extraction under the condition that the flow ratio is 1:5 to obtain raffinate A1 and a loaded organic phase B1.

After the loaded organic phase B1 is washed, 8-stage countercurrent back extraction is carried out by adopting 5mol/L sodium hydroxide solution, the back extraction flow ratio is 2:1, and a vanadium-chromium-containing back extraction solution A2 and a back extraction organic phase B2 are obtained; and the back extraction organic phase is transformed by sodium bicarbonate and then returns to the extraction process, the total extraction rate of vanadium is 99.1 percent, the extraction rate of chromium is 86.5 percent, and the consumption of sodium hydroxide is 1.6 times of the molar ratio of Na/(V + Cr) in the sodium roasting water extract of the vanadium slag in the whole extraction and back extraction processes.

Through the embodiment 6 and the comparative example 2, the fact that partial vanadium extraction treatment is not carried out in advance can affect the recovery of elements to a certain extent, particularly greatly increases the consumption of stripping alkali and affects the recovery of sodium in the whole process.

Example 7

Taking 4L vanadium slag sodium salt roasting water leachate containing V30 g/L and Cr 1.1g/L, introducing carbon dioxide to adjust the pH value of the leachate to 8.5, and then regulating the pH value according to NH₃Adding ammonium carbonate with the molar ratio of 1 time of that of the vanadium to the vanadium, stirring the mixture for 3 hours at room temperature, and then filtering and separating the mixture to obtain ammonium meta-acid crystals and filtrate A, wherein the recovery rate of the vanadium is 78%; calcining ammonium metavanadate at 500 ℃ for 2h to obtain a vanadium pentoxide product containing 99.3 percent of vanadium, wherein the content of Cr is 0.03 percent.

Filtrate A was mixed with an extractant composed of 40% methyl trialkyl (R in the formula 1)₁～R₃Is C₈～C₁₀Linear alkyl radical of (2), R₄Is methyl, A^-Is CO₃ ^2-) Organic phases of + 20% of secondary octanol and 40% of sulfonated kerosene (volume percentage) are mixed, and then 3-stage countercurrent extraction is carried out under the condition that the flow ratio is 1:10, so as to obtain raffinate A1 and a loaded organic phase B1. The loaded organic phase B1 is used for the subsequent separation and extraction of vanadium and chromium.

The roasting material of the sodium salt of the vanadium slag containing 20.4 percent of V and 3.9 percent of Cr is taken, raffinate A1 (raffinate A1 firstly recovers sodium carbonate through freezing crystallization) is added according to the solid-to-liquid ratio of 1:6g/L, the mixture is stirred and leached for 5 hours at the temperature of 80 ℃, the solid and the liquid are separated, the leaching rate of the vanadium is 95.1 percent, and the leaching rate of the chromium is 78.6 percent.

Comparative example 3

Compared with the embodiment 7, the main difference is that the carbonate extractant is not adopted, and specifically comprises the following components:

taking 4L vanadium slag sodium salt roasting water leachate containing V30 g/L and Cr 1.1g/L, introducing carbon dioxide to adjust the pH value of the leachate to 8.5, and then regulating the pH value according to NH₃Adding ammonium carbonate with the molar ratio of 1 time of that of the vanadium to the vanadium, stirring the mixture for 3 hours at room temperature, and then filtering and separating the mixture to obtain ammonium meta-acid crystals and filtrate A, wherein the recovery rate of the vanadium is 78%; calcining ammonium metavanadate at 500 ℃ for 2h to obtain a vanadium pentoxide product containing 99.3 percent of vanadium, wherein the content of Cr is 0.03 percent.

Filtrate A was mixed with a commercial methyl trialkyl ammonium chloride (formula 1, R)₁～R₃Is C₈～C₁₀Linear alkyl radical of (2), R₄Is methyl, A^-Is Cl^-) Organic phases of + 20% of secondary octanol and 40% of sulfonated kerosene (volume percentage) are mixed, and then 3-stage countercurrent extraction is carried out under the condition that the flow ratio is 1:10, so as to obtain raffinate A1 and a loaded organic phase B1. The loaded organic phase B1 is used for the subsequent separation and extraction of vanadium and chromium.

Adding raffinate A1 into a vanadium slag sodium salt roasted material containing 20.4 percent of V and 3.9 percent of Cr according to the solid-to-liquid ratio of 1:6g/L, stirring and leaching for 5 hours at 80 ℃, and carrying out solid-liquid separation, wherein the leaching rate of vanadium is 78.1 percent, and the leaching rate of chromium is 49.7 percent.

The extraction agent is not adopted, so that the overall effect of the process is greatly influenced, and the recovery of elements is influenced.