RU2456241C2 - Method of producing vanadium oxide through extraction - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing high-purity vanadium oxide via extraction. The method involves preparing the starting substance for firing, firing with liming, leaching, separating the undissolved residue, mixing the leaching product with a saponified organic phase to carry out extraction, treating the extraction products with sulphuric acid to obtain an ammonium polyvanadate residue which is calcined to obtain V₂O₅ or reducing the ammonium polyvanadate to obtain V₂O₃, wherein waste water from extraction is returned into the system for circulation and reuse after neutralisation treatment with lime milk.

EFFECT: invention increases rate of extracting vanadium and reduces the cost of the product, enables to obtain a vanadium product of high quality and recycle waste water from vanadium extraction.

11 cl, 1 dwg, 12 tbl, 3 ex

Description

Technical field

The present invention relates to a method for producing vanadium oxide using extraction and relates to the field of vanadium oxide extraction.

State of the art

The conventional vanadium extraction method using the sodium salt includes the selection of common sodium salts, such as Na ₂ CO ₃ , Na ₂ SO ₄ or NaCl, as additives and firing the sodium salt with the vanadium-containing starting material at high temperature, where vanadium is in the starting material the substance is oxidized to V ⁵⁺ with atmospheric oxygen and then V ⁵⁺ binds to the sodium salt to form sodium vanadate, which is readily soluble in water; leaching the calcined product with water to dissolve sodium vanadate in solution, performing solid-liquid separation, then removing major impurities, such as P, Si and so on, from the solution using CaCl ₂ , adding ammonium salts such as (NH ₄ ) ₂ SO ₄ , NH ₄ Cl, (NH ₄ ) ₂ CO ₃ or NH ₄ NO ₃ , etc., adjusting the pH of the solution in the range of 1.5-2.5, heating the solution above 90 ° C and maintaining at this temperature for 40-90 min to isolate ammonium polyvanadate from the precipitate; removing impurities such as sodium salts precipitated from ammonium polyvanadate, washing with water after filtration, drying and calcining the precipitate to remove ammonia to produce V ₂ O _5, or reducing the precipitate at high temperature with a reducing gas such as coal gas or natural gas to obtain V ₂ O ₃ . Currently, the largest number of manufacturers in the world adheres to this method of obtaining vanadium products.

This method has the advantages of high product quality, stable method and easy control. However, the ammonium salt is used in an amount higher than the theoretical amount during the precipitation of vanadium to obtain a high-quality vanadium product, so that the wastewater after precipitation of vanadium has a high concentration of ammonia nitrogen and sodium salt and is the most difficult to process, for example, the concentration of NH ₄ ⁺ it is usually as high as 2000-8000 mg / l or even higher, and the concentration of Na ⁺ may be higher than 20 g / l. Therefore, wastewater treatment is the most difficult problem to manipulate in a vanadium extraction method using sodium salt. If the wastewater is directly returned to the leaching stage for circulation, when the sodium vanadate in the calcined product (also called the “calcined product”) is continuously dissolved in water, when the sodium salt cannot be discharged from the solution, then the concentration of sodium salt in the solution becomes significantly higher, the amount of salt the ammonia required to precipitate vanadium becomes significantly larger, the solution quickly becomes viscous, it becomes difficult to filter or precipitate vanadium, and in fact It may continue after 1-2 cycles, so the wastewater can not be directly circulated and reused. Currently, there are mainly two schemes for solving the problems of wastewater pollution from the method of extraction of vanadium using sodium salt. One scheme is the removal of heavy metals, the implementation of ammonia removal and sodium removal treatment and then unloading, where the ammonia removal method mainly includes an air purification method, a membrane separation method, a magnesium ammonium phosphate precipitation method, a chemical oxidation method, a zeolite adsorption method and a method biological nitrogen removal, and the sodium removal method mainly follows the crystallization concentration method. The disadvantages of this scheme include that the cost of the ammonia removal treatment and the sodium removal treatment is too high to be accepted for industrial plants, probably new contaminants appear during processing and the regenerated sodium salt is sodium sulfate containing many impurities that will emit SO ₂ , which pollutes the environment after firing and therefore is not suitable as a firing additive. Another scheme is the removal of heavy metals, the implementation of ammonia removal and sodium removal treatments, and the return of condensed water for circulation. The difference from the first scheme is that the water of the first scheme does not circulate, but is consistent with the national standard for industrial wastewater (≤ 15 mg / l for ammonia nitrogen in wastewater), so it is very difficult to agree on a standard and requires a high price, although the second scheme does not discharge wastewater, a large amount of energy is used to evaporate the wastewater, which also has a disadvantage, a high price, and usually non-regenerable evaporated gaseous ammonia.

Therefore, there is an urgent need for solutions in the field of treatment and disposal of wastewater having a high content of ammonia nitrogen and a high content of sodium salt as a result of a method of extracting vanadium using sodium salt.

From the 1960s and 1970s, a vanadium extraction method using lime or limestone as a firing additive, commonly referred to as a vanadium extraction method using calcium salt, or a calcination vanadium extraction method that targets some of the inherited disadvantages of the vanadium extraction method using the sodium salt was investigated. including (1) a certain restriction on the CaO content (less than 1.5%) in vanadium slag, because the yield of extracted vanadium is reduced by 4.7–9%, so that burning of CaO in slag increases by 1%; (2) the high price due to the large expendable amount of sodium salt and ammonium salt; and (3) environmental pollution caused by the large amount of sodium salt and ammonium salt in wastewater. The calcined product of the vanadium extraction method using the calcium salt may be leached with sulfuric acid or carbonate or bicarbonate.

In German patent application No. 2324737 and British patent application No. 1394024, a method for leaching a calcined product with liming with a solution of sodium carbonate is described. US Pat. No. 3,853,985 describes a method for leaching a calcined product with liming with ammonium carbonate or bicarbonate. The publication Thermodynamics and kinetics of vanadium slag calcium salt roasting-carbonate leaching (Vanadium titanium, 1997, No.6: 1-6) describes the thermodynamics and kinetics of leaching of a calcined calcined calcined carbonate and bicarbonate product. Due to the use of sodium salt and ammonium salt, the above methods in the literature also have the problem of treating wastewater with ammonia nitrogen.

UK patent application No. 1394024 also describes a method comprising leaching the calcined product with sulfuric acid or hydrochloric acid, adjusting the pH of the acidic leaching product in the range of 1.6-1.9, heating for hydrolysis and precipitation of vanadium, drying and calcining the precipitate to obtain a vanadium oxide product containing approximately 93.5% V ₂ O ₅ and a significant amount of impurities. The publication "Study of V ₂ O ₅ extraction process by vanadium slag lime roasting method" (Iron Steel Vanadium Titanium, 1992, 13 (6): 1-9) describes a study of the production of V ₂ O _{5 by} affecting the crushed vanadium slag calcining and sulfuric acid leaching, in which sulfuric acid is added to the obtained acid leaching product to adjust the pH to 2, and then heating to hydrolyze and precipitate vanadium to give a product with a purity of 93.6-93.92%. The publication "Study of V ₂ O ₅ extraction by vanadium slag calcium salt roasting-sulfuric acid leaching" describes a calcination study with liming and leaching of vanadium slag by sulfuric acid. The Tula Vanadium Plant of the Former Soviet Union, the world's first (also the only) vanadium plant, which adheres to the method: calcination with lime - leaching with sulfuric acid - precipitation of vanadium by hydrolysis, which can give the product V ₂ O ₅ with a purity of 88-94% (in average 92%) and containing the main impurities Mn, Mg and Ca, and then the melting of the product V ₂ O ₅ in vanadium - iron (ferrovanadium), also containing many impurities; therefore, the manufacturer is not competitive on the international market and mainly supplies the product to the domestic market, which is the main reason why other vanadium plants do not adhere to this method.

To improve the competitiveness of the product on the market, in Russian patent application No. 2001127026/02 and 96106854/02, a method for producing high-quality vanadium oxide from a hydrolyzed precipitate containing impurities of Mn, Ca and Mg is described. The method involves using NaOH to dissolve the hydrolyzed precipitate, then adding an ammonium salt like ammonium sulfate, along with heating, precipitating ammonium polyvanadate and calcining to produce high-quality vanadium oxide with a V ₂ O ₅ content higher than 98%. The method reduces the total amount of wastewater containing ammonia, but still requires wastewater treatment, including the removal of ammonia and the removal of sodium; therefore, there are technical and economic difficulties of a high price and still a difficulty in treating wastewater with ammonia nitrogen, in addition, a decrease in the rate of vanadium extraction to some extent due to the long processing method and complex methods.

To date, there is no corresponding publication regarding a method that can not only produce a high-quality vanadium product, but also completely solve the problem of treating and reusing waste water from vanadium extraction.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a method for producing vanadium oxide, in which it is possible not only to obtain a high-quality vanadium product, but also to circulate and reuse the vanadium extraction wastewater.

The method for producing vanadium oxide in the present invention includes the following steps, including:

a) mixing the vanadium-containing substance with the additive to obtain a mixed substance, where the additive is CaO or limestone and the amount of additive in the mixture, the mass ratio of CaO / V ₂ O ₅ is 0.5-1.4: 1;

b) calcining the mixed substance at 860-950 ° C in an oxidizing atmosphere for 60-240 minutes to obtain a calcination product;

c) adding water to the calcined product to obtain a suspension, stirring and slowly adding a solution of sulfuric acid to leach the suspension, while adjusting the pH in the range of 2.5-3.5;

d) removing the leach residue to obtain a leach product, exposing the leach product to a P-removal treatment and a Ca-removal treatment to obtain a total mass ratio of V to P in the leach product ≥ 1000 and [Ca ^2- ] in the leach product ≤ 0, 05 g / l, washing the residue with circulating water to obtain the washing water used to prepare the suspension for the next leaching;

e) the effect on the leachate after removal of P and removal of Ca extraction using an extraction agent that is saponified with ammonia, and then the separation of the aqueous phase and the organic phase, and the mass ratio of NH ₃ / Mn in the aqueous phase is regulated in the range of 0.6-2000: 1, and the extraction agent is able to extract Mn ²⁺ , Mg ²⁺ and Fe ³⁺ at a pH of 2-5;

f) adjusting the pH of the aqueous phase with sulfuric acid in the range of 1.5-2.5, heating to a temperature of 90 ° C to the boiling point, keeping at this temperature for 30-120 minutes, filtering and washing and drying the precipitate to obtain ammonium polyvanadate exposing the ammonium polyvanadate to calcination to remove ammonia to produce V ₂ O _5; or recovering the ammonium polyvanadate to produce V ₂ O ₃ and

g) removing impurities P, Mn and Mg in the wastewater formed in step f to create Mn ²⁺ and Mg ²⁺ concentrations lower than 5 g / l, respectively, and a P concentration lower than 0.005 g / l to produce circulating water, and returning the circulating water to stage c for preparing a suspension and to stage d for washing the residue,

where the solid starting material used in the above steps has a total amount of alkali metal of not more than 0.3 wt.% and the total amount of Cl ^- and NO ₃ ^is not more than 0.1 wt.%, and a liquid starting material used on the above stages, has a total amount of alkali metal of not more than 0.1 g / l and a total amount of Cl ^- and NO ₃ ^- not more than 0.1 g / l.

According to the present invention, the wastewater can be circulated and reused; and in addition, the method of the invention provides calcining and leaching with sulfuric acid to produce a vanadium solution substantially free of alkali metal ions, and various starting materials (including added water) are substantially free of readily soluble alkali metal, halogen and nitrate ions, moreover, the balance of readily soluble ions can be maintained during the circulation method, the wastewater can be circulated and reused after treatment, and thus the processing problems are avoided and wastewater conventional vanadium extraction process using sodium salt.

In step a, the vanadium-containing substance may be various vanadium-containing starting materials used to produce vanadium oxide, such as vanadium-containing slag or other vanadium-containing starting materials (such as vanadium-containing magnetite and vanadium-lead-zinc ore, etc.), preferably vanadium-containing slag. .

Preferably, in step a, the mixed substance is sprayed to a particle size of 0.1 mm or less to obtain vanadium readily oxidized in V ⁵⁺ to give vanadate.

In step b, the oxidizing atmosphere may be pure oxygen, air, or a mixture of oxygen and an inert gas. Preferably, the inert gas is nitrogen gas. In the present invention, during firing, a suitable temperature and time for firing can be selected within the range, for example, when the firing temperature is high (such as 950 ° C), the firing time can be shortened (such as 60 minutes), and when the firing temperature is low (such as 860 ° C), the firing time may be longer (approximately 240 min).

Preferably, in step c, the calcined product is cooled and sprayed to 0.18 mm or less to facilitate leaching before suspension.

Preferably, in step c, a suspension is prepared by mixing the calcined product with water in an amount that is a multiple of 1.5-4 by weight. The water used is the washing water obtained by washing the residue, and if the washing water is insufficient, circulating water is used to replenish. The leaching solution of sulfuric acid has a concentration of 10-75%, the leaching temperature is from room temperature to 58 ° C, and the leaching time is 30-90 minutes. More preferably, the pH of the suspension is controlled in the range of 2.8-3.3 with a solution of sulfuric acid 32-65 wt.%.

During the washing of the residue, the washing is preferably carried out 5-7 times, the amount of water used for each washing is preferably 20-35% by weight of the residue, based on a dry base, in order to maintain the balance of the water in the circulating method.

The P removal reagent can be used for P-removal treatment to satisfy the TV / P≥1000 inequality. The Ca removal reagent can be used for the Ca removal treatment to satisfy the inequality [Ca ²⁺ ] ≤0.05 g / L.

In step e, the extraction agent may be an organic substance capable of extracting Mn ²⁺ , Mg ²⁺ and Fe ³⁺ at a pH of 2-5, and is preferably at least one of bis (2-ethylhexyl) phosphate, mono- (2-ethylhexyl) 2-ethylhexylphosphonate and bis- (2,4,4-trimethylpentyl) hypophosphoric acid. The extraction agent can be diluted before use with any well-known solvent, such as selective # 260 # oil or sulfonated kerosene.

The extraction agent is preliminarily saponified with ammonia to convert the most changing groups in the extraction agent to NH ₄ ⁺ , while maintaining the existence of H ⁺ . Preferably, the extraction agent is pre-saponified with ammonia so that the raffinate has a pH of 2.8-3.8. Alkali alkali metals such as sodium hydroxide or potassium hydroxide cannot be used for saponification.

In addition, in stage e, after extraction, the organic phase containing Mn ²⁺ , Mg ²⁺ and Fe ³⁺ can be subjected to reversible extraction using a 2-3 M solution of sulfuric acid to reversibly extract the impurities Mn ²⁺ , Mg ²⁺ into a solution of sulfuric acid, so that the organic phase is regenerated and can be reused. The solution obtained by reversible extraction can be used for reversible extraction of Mn and can be used for regeneration of Mn, and the residual neutralization of wastewater after reversible extraction is reduced. When Fe in the leachate accumulates to some extent in the organic phase, Fe reversibly extracted with 6N hydrochloric acid and the organic phase is recycled to the system after removing the Cl ^- washing.

In step g, the wastewater can be treated according to various conventional methods for removing P, Mn and Mg, for example, milk of lime is used to neutralize the wastewater to a pH of 9-11, the wastewater is filtered to remove major impurities, such as Mn, P and Mg, in at the same time, obtaining a neutralized waste water residue used as a starting material for the extraction of Mn; or Mn can be separately recovered by other reagents and then impurities like Mn, P and Mg are removed.

Since the returned circulating water may contain a certain amount of NH ₄ ⁺ , if the mass ratio of NH ₃ / Mn in the leached product with removed P and removed Ca already satisfies the above requirement, extraction is not added and vanadium is precipitated directly.

The present invention has the following beneficial effects.

1. The method of the invention adheres to the calcination method with liming and sulfuric acid leaching to obtain a vanadium solution essentially free of alkali metal ions; and various starting materials (including added water) are substantially free of readily soluble alkali metal, halogen, and nitrate ions, so that during the circulation it is possible to maintain a balance of readily soluble ions and eliminate the problems of treating wastewater with a conventional vanadium extraction method using a sodium salt.

2. Extraction is used to replace impurities like Mn, P, and Mg with NH ₄ ⁺ ion to purify the vanadium-containing solution to obtain a high-quality vanadium oxide product, so that the technical problem is solved by which, using the conventional method, calcining with sulfuric acid leaching It is not possible to obtain a high quality vanadium product.

3. The NH ₃ / Mn mass ratio is adjusted to control the degree of extraction when the indicated ratio in the leachate is lower than the quantitative value indicated in the present invention, the ratio is extracted to a predetermined value and then vanadium is precipitated; when the ratio in the leachate product already reaches the value established in the present invention, extraction is not necessary and vanadium is precipitated directly and part of the NH ₄ ^{+ is} discharged together with the ammonium polyvanadate precipitate, so that the concentration of NH ₄ ⁺ in the system does not continuously increase, which makes it possible circulation and reuse.

4. Used for leaching circulating water containing a sulfate salt, such as (NH ₄ ) ₂ SO ₄ ; within the leaching condition in the present invention, NH ₄ ⁺ will not cause adverse effects and SO ₄ ^2- is useful for increasing the rate of leaching of the calcined calcined product, so that circulation and reuse of water can ultimately be realized.

5. The method of the invention can significantly increase the total rate of extraction (up to 82-85%) of vanadium oxide from vanadium slag, at the same time, the extraction rate of the conventional vanadium extraction method using sodium salt is approximately 80%; therefore, the method of the invention has an increased extraction rate of 2-5% on average compared to the conventional vanadium extraction method using the sodium salt, and the resulting vanadium product is of good quality and complies with Chinese National Standard No. GB3283-87.

6. An inexpensive lime substance is used to replace expensive sodium carbonate, the amount of sulfuric acid consumed is similar to the amount in the vanadium extraction method using sodium salt, and the consumption and price of other excipients are reduced; therefore, the consumption and price of various auxiliary and starting materials is significantly reduced.

Brief Description of the Drawings

1 is a flow chart of one preferred embodiment of the method of the present invention.

Preferred Embodiments

The present invention will now be described by the following examples.

All of the following examples adhere to the process sequence as shown in FIG. Preferred examples are briefly described in conjunction with FIG.

First, vanadium slag and lime are mixed to obtain a mixed substance (equivalent to stage a).

The mixed substance is calcined and calcined (equivalent to step b).

A solution of sulfuric acid is used to leach the calcined product at a constant pH (equivalent to step c).

After leaching, the residue and the leaching product are separated, the residue is washed with a diluted solution of sulfuric acid with a pH of 3-6, and the washing water is collected to prepare a suspension (equivalent to stage d).

The leachate is subjected to extraction (equivalent to step e).

Vanadium is precipitated and the ammonium polyvanadate obtained after vanadium precipitation is calcined or reduced to produce high-quality vanadium oxide (equivalent to step f).

The wastewater obtained after precipitation of vanadium is added, the milk of lime to neutralize, the resulting circulating water is returned for suspension or washing the residue and Mn is recovered from the neutralization residue (equivalent to step g).

Example 1

The calcined product obtained according to step (1) is used, 51 cycles of the wastewater circulation test are carried out according to the method of the invention, and each cycle includes steps (2) to (6).

(1) Obtaining a firing product

Conventional vanadium slag with the composition shown in Table 1 is ground to less than 0.098 mm, 28 kg of ground vanadium slag powder is mixed with 1.96 kg of lime (ground to less than 0.1 mm) containing CaO ≥ 98%, and then the mixture calcine at 860 ° C in air for 240 minutes, cool and grind to less than 0.18 mm.

Table 1. The main components of vanadium slag (%) V ₂ O ₅ Cao MnO P K + Na 16.67 3,54 9.14 0.04 0.21

(2) Leaching of the firing product

2000 ml of water obtained by washing the remainder of the last cycle (pure water is used for the first cycle) is added to 500 g of the ground firing product for suspension preparation, 10-32 wt.% Sulfuric acid solution is slowly continuously added, along with stirring, during The leaching method adjusts the pH in the range of 2.8-3.3, at the same time, the suspension temperature is maintained at a temperature of from room temperature to 58 ° C, the reaction is carried out for 60 minutes. The resulting product is filtered to obtain a leach product, the residue is washed with circulating water (pure water is used for the first cycle) 6-7 times, the water used for each time is 120 ml, the washing water is combined to prepare a leach suspension in the next cycle and the residue is dried and weighed to determine the content of TV (total vanadium), and the leaching rate of vanadium is calculated. The leachate is subjected to P-removal treatment and Ca-removal treatment to obtain a P value satisfying the inequality TV / P≥1000 and [Ca ²⁺ ] ≤0.05 g / l, and then extraction is carried out.

(3) Extraction

10-20 vol.% Solution of kerosene P204 saponified with ammonia. The saponified organic phase is mixed with the leachate to effect a one-step extraction at room temperature for 5 minutes with stirring. The mixture is left to settle for phase separation and the organic matter remaining in the aqueous phase is removed. The mass ratio of NH ₃ / Mn in the aqueous phase solution is adjusted to establish 0.6-50: 1 by adjusting the saponification ratio and the extraction phase.

Note: P204 is bis (2-ethylhexyl) phosphate.

(4) Precipitation of vanadium and production of V ₂ O ₅ by calcination

A small amount of sulfuric acid is used to adjust the pH of the aqueous phase after removing the oil layer, in the range of 1.5-2.5, then the resulting product is heated above 90 ° C, held for 60-120 minutes and filtered, the precipitate is washed with water from a tap containing [Na + K] ≤0.1 g / L, 3 times, and the water used each time is 30 ml, and the wastewater was combined with the liquid above the vanadium precipitate to obtain vanadium precipitation wastewater.

The precipitate of ammonium polyvanadate is dried, calcined and alloyed at 500-800 ° C to obtain V ₂ O ₅ and the composition of the obtained V ₂ O _{5 is} analyzed.

(5) Wastewater treatment

A low-water lime milk is prepared, vanadium precipitation is added to the wastewater to adjust the pH of the solution in the range of 9.0-10.0 and filtered. In the filtrate, adjust the pH in the range of 5-7 with dilute sulfuric acid to obtain circulating water, like water after washing the residue, for leaching in the next cycle. The neutralization residue obtained after filtration was used as starting material for the extraction of Mn.

(6) Organic phase regeneration

The organic phase containing a cation such as Mn ²⁺ (entrained in the organic phase) is reused after reversible extraction with a 2.5 M sulfuric acid solution. After 10 cycles, the organic phase is reversibly extracted with 6 N hydrochloric acid in addition to a 2.5 M solution of sulfuric acid and washed with diluted sulfuric acid to remove Cl ^- , and then the extraction agent is returned to the system. The solution obtained by reversible extraction with hydrochloric acid and the solution obtained by reversible extraction with a solution of sulfuric acid are treated separately. When Mn in a reversible extraction solution accumulates to some extent, the reversible extraction solution interacts with the neutralization residue of the wastewater with the regeneration of Mn.

The above steps (2) to (6) are repeated, 500 g of the calcination product is used in each cycle, the liquid-solid ratio for each cycle is 4: 1, vanadium is not precipitated after leaching in the first cycle, the leaching product is used to prepare the suspension in a second cycle to increase the concentration of vanadium in the leachate; then, during leaching in each of the remaining cycles, the remaining wash water from the last cycle is used in stage (2) and the remaining part is replenished with circulating water; Circulating water is used to wash the residue, and the missing part is replenished with clean water. Carry out 51 cycles and do not discharge waste water containing ammonia nitrogen from the system.

In addition to the first cycle without vanadium precipitation, the maximum value, minimum value and average value of the extraction rate from the remaining cycles are presented in table 2; the maximum value, minimum value and average value for chemical compositions of the product V ₂ O ₅ from the remaining cycles are presented in table 3 and table 3 also shows the metallurgical compositions No. 98 and No. 99 Chinese National Standard No. GB3283-87; the maximum value, minimum value and average value for the composition of the circulating water after the circulation treatment for the remaining cycles are presented in table 4.

Table 2. The rate of extraction of vanadium in the circulation method (%) Operation Pretreatment of the starting material Leaching Extraction Vanadium precipitation Removal of ammonia by calcination Total extraction speed Minimum 89.98 96.05 98.57 Maximum 98.50 93.10 97,42 99.36 97.00 84.20 Average 91.85 96.87 99.04

The rates of extraction of the pretreated starting material and removal of ammonia by calcination in Table 2 above are obtained from long-term industrial production data.

Note: the pretreatment operation of the starting material involves spraying a mass of untreated vanadium slag, grinding and removing iron, and a small amount of vanadium is lost in this method.

Based on table 2, it can be noted that the total average rate of extraction of V ₂ O ₅ from vanadium slag by the method of the invention reaches 84.20%.

Table 3. The main components of the product V ₂ O ₅ obtained by the circulation method (%) Line items V ₂ O ₅ Mn Mg Ca TFe P S Si Na ₂ O + K ₂ O Minimum 98.81 <0.01 <0.01 0.01 0.01 0.02 0.01 <0.01 0.10 Maximum 99.47 0.15 0.04 0.09 0.12 0.05 0,03 0.02 0.28 Average 99.12 0.09 0,03 0.05 0.05 0,03 0.02 0.02 0.23 GB3283-87 Metallurgical 98 > 98 ≯0.3 ≯0.05 ≯0.03 ≯0.25 ≯1.5 GB3283-87 metallurgical 99 > 99 ≯0.2 ≯0.03 ≯0.01 ≯0.15 ≯1.0

Table 3 shows that the vanadium product obtained by this method is a good quality product and complies with Chinese National Standard No. GB3283-87.

Table 4. The main components of the circulating water (g / l) Line items Mn Mg NH ₄ ⁺ Na + K Ca SO ₄ ^2- P Al Si TFe TCr Minimum 1.87 1.46 1.71 0.20 0.43 18.61 <0.005 Maximum 3.42 3.76 3.69 0.39 0.98 30.27 Average 2.71 2.70 2.78 0.30 0.73 24.91 <0.005

Based on table 4, it can be noted that after 51 cycles of wastewater circulation, various impurity ions do not tend to enrich (accumulate), and the circulation and reuse of vanadium extraction wastewater is realized at a low price, where K and Na mainly occur from the starting material of vanadium slag and the sum of K + Na in the circulation water is stabilized in the range of 0.2-0.4 g / l and does not increase after 51 cycles.

Example 2

A calcined product obtained according to step (1) is obtained, a 51 test cycle with wastewater circulation is carried out according to the method of the invention, and each cycle includes steps (2) to (6).

(1) Obtaining a firing product

The vanadium slag shown in Table 5 is pulverized to less than 0.098 mm.

Table 5. The main components of vanadium slag (%) V ₂ O ₅ Cao Mn P K + Na 13.75 4.93 6.56 0,049 0.19

28 kg of the crushed vanadium slag powder are mixed with 1.82 kg of lime (crushed to less than 0.1 mm) containing 98% CaO, and then the mixture is calcined at 950 ° C in air for 60 minutes, cooled and crushed to less than 0 , 18 mm.

(2) Leaching of the firing product

1250 ml of water obtained by washing the remainder of the last cycle (pure water is used for the first cycle) is added to 500 g of ground firing product for suspension preparation, 32-65 mass% sulfuric acid solution is slowly added continuously, along with stirring, the pH is adjusted to the range of 2.8-3.3 during the leaching method, at the same time, the suspension temperature is maintained at a temperature of from room temperature to 58 ° C, the reaction is carried out for 60 minutes The resulting product is filtered to obtain a leach product, the residue is washed with circulating water (clean water is used for the first cycle) 6 times, the water used each time is 120 ml, the washing water is combined to prepare a leach suspension in the next cycle, and the residue is dried and weighed determining the content of TV (total vanadium) and calculating the leaching rate of vanadium. The leachate is subjected to a P-removal treatment and a Ca-removal treatment so that P satisfies the inequality TV / P≥1000 and [Ca ²⁺ ] ≥1000 and [Ca ²⁺ ] ≤0.05 g / L and then extraction is carried out.

(3) Extraction

10-30 vol.% Solution of kerosene P507 saponified with ammonia. The saponified organic phase is mixed with the leachate to effect a one-step extraction at room temperature for 5 minutes, with stirring. The mixture was left to stand for phase separation and the organic matter remaining in the aqueous phase was removed. The mass ratio of NH ₃ / Mn in the aqueous solution phase is adjusted so as to establish 10-200: 1 by adjusting the saponification ratio and the extraction phase ratio.

Note: P507 is mono (2-ethylhexyl) -2-ethylhexylphosphonate.

(4) Precipitation of vanadium and production of V ₂ O ₅ by calcination

A small amount of sulfuric acid is used to adjust the pH of the aqueous phase solution in the range of 1.5-2.5, then the resulting product is heated above 90 ° C, held for 60-120 minutes and filtered, the precipitate is washed with water from a tap containing [ Na + K] ≤0.1 g / l, 3 times and each time the used water is 30 ml, the washing wastewater is combined with the liquid above the vanadium precipitate to obtain vanadium precipitation wastewater.

The precipitate of ammonium polyvanadate is dried, calcined and alloyed at 500-800 ° C to obtain V ₂ O ₅ and the composition of the obtained V ₂ O _{5 is} analyzed.

(5) Wastewater treatment

A low-water lime milk is prepared, vanadium precipitation is added to the wastewater to adjust the pH of the solution in the range of 9.5-10.00 and filtered. In the filtrate, the pH is adjusted in the range of 5-7 with diluted sulfuric acid to obtain circulating water as water for washing the leach residue in the next cycle. The neutralization residue obtained after filtration is used as the starting material for the extraction of Mn.

(6) Organic phase regeneration

The organic phase containing a cation such as Mn ²⁺ is reused after reversible extraction with a 2.5 M sulfuric acid solution. After 10 cycles, the organic phase is reversibly extracted with 6 N hydrochloric acid in addition to a 2.5 M solution of sulfuric acid and washed with diluted sulfuric acid to remove Cl ^- and then the extraction agent is returned to the system. The solution obtained by reversible extraction with hydrochloric acid and the solution obtained by reversible extraction with a solution of sulfuric acid are treated separately. When Mn in the solution of reversible extraction accumulates to some extent, the solution of reversible extraction interacts with the remainder of the neutralization of wastewater with the regeneration of Mn.

The above steps (2) to (6) are repeated, 500 g of the calcination product is used in each cycle, the liquid-solid ratio for each cycle is 2.5: 1, vanadium is not precipitated after leaching in the first cycle, the leaching product is used to prepare suspensions of the second cycle to increase the concentration of vanadium in the leachate, then during leaching in each of the remaining cycles, the washing water of the remainder of the last cycle is used in stage (2) and the missing part is supplemented with circulating water; circulating water is used to wash the residue and supplement the missing part with clean water. Carry out 51 cycles and do not discharge waste water containing ammonia nitrogen from the system.

Excluding the first cycle without vanadium precipitation, the maximum value, minimum value and average value of the extraction rate in the remaining cycles are shown in table 6; the maximum value, minimum value and average value for chemical compositions of the product V ₂ O ₅ in the remaining cycles are shown in table 7; and the maximum value, minimum value and average value for the composition of the circulating water after the circulation treatment for the remaining cycles are shown in table 8.

Table 6. The rate of extraction of vanadium in the circulating method (%) Procedure Pretreated starting material Leaching Extraction Vanadium precipitation Removal of ammonia by calcination Total extraction speed Minimum 90.12 96.33 98.57 Maximum 98.50 93.69 97.78 99.44 97.00 84.48 Average 91.98 97.08 99.02

The extraction rates of the pre-treated starting material and the removal of ammonia by calcination in the above table 6 are obtained from long-term industrial production data.

Based on table 6, it can be noted that the total average rate of extraction of V ₂ O ₅ from vanadium slag by the method of the invention reaches 84.48%.

Table 7. The main components of the product V ₂ O ₅ obtained by the circulation method (%) Line items V ₂ O ₅ Mn Mg Ca TFe P S Si Na ₂ O + K ₂ O Minimum
naya 98.79 <0.01 <0.01 <0.01 0.01 0.02 0.01 <0.01 0.18 The maximum
naya 99.53 0.11 0,03 0.08 0.10 0.04 0,03 0.02 0.31 Average 99.25 0.08 0.02 0.05 0.06 0,03 0.02 0.02 0.25

Table 7 shows that the vanadium product obtained by this method has good product quality and complies with Chinese National Standard No. GB3283-87.

Table 8. The main components of the circulating water (g / l) Line items Mn Mg NH ₄ ⁺ Na + K Ca SO ₄ ^2- P Si Al TFe TCr Minimum 0.98 1.06 2.11 0.18 0.51 16.84 <0.005 Maximum 2.47 2.95 4.34 0.34 0.67 27.34 Average 1.73 2.01 3.23 0.26 0.59 22.09 <0.005

Based on table 8, it can be noted that after 51 cycles of wastewater circulation, various impurity ions do not tend to accumulate and circulation and reuse of vanadium extraction wastewater is realized, where K and Na are mainly present from the starting material of vanadium slag and the sum K + Na in the circulation water is stabilized in the range of 0.1-0.4 g / l and does not increase after 51 cycles.

Example 3

The calcined product obtained in accordance with step (1) is used, in accordance with the method of the invention, 100 cycles of a wastewater circulation test are carried out and each cycle includes steps (2) to (6).

(1) Obtaining a firing product

110 kg of vanadium slag with the composition shown in table 9 is crushed to less than 0.098 mm, the powder of crushed vanadium slag is mixed with 7.7 kg of lime (crushed to less than 0.1 mm) containing 98% CaO, and then the mixture is fired at 920 ° C in air for 150 minutes, cooled and ground to less than 0.18 mm.

Table 9. The main components of vanadium slag (%) V ₂ O ₅ CaO Mn P K + Na 12.68 2.15 5.98 0.147 0.18

(2) Leaching of the firing product

2000 ml of water obtained by washing the residue from the last cycle (pure water is used for the first cycle) is added to 1000 g of the ground firing product for suspension preparation, 50-75% sulfuric acid solution is slowly continuously added with stirring, during the pH leaching method regulate in the range of 2.8-3.3, at the same time, the suspension temperature is maintained at a temperature of from room temperature to 58 ° C, the reaction is carried out for 60 minutes The resulting product is filtered to obtain a leach product, the residue is washed with circulating water (pure water is used for the first cycle) 5-6 times, each time the amount of water used is 250 ml, the washing water is combined to prepare a leach suspension in the next cycle and the residue is dried and weighed to determine the content of TV (total vanadium) and calculate the leaching rate of vanadium. The leachate is subjected to a P-removal treatment and a Ca-removal treatment to obtain P satisfying the inequality TV / P≥1000 and [Ca ²⁺ ] ≤0.05 g / l, and then extraction is carried out.

(3) Extraction

10-30 volume. % solution of kerosene Cyanex saponified with ammonia. The saponified organic phase is mixed with the leachate to effect a one-step extraction at room temperature for 5 minutes, with stirring. The mixture was left to stand for phase separation and the organic matter remaining in the aqueous phase was removed. The mass ratio of NH ₃ / Mn in the aqueous phase solution is adjusted to be 20-2000: 1 by adjusting the saponification ratio and the extraction phase ratio.

Note: Cyanex is bis (2,4,4-trimethylpentyl) hypophosphoric acid.

(4) Precipitation of vanadium and production of V ₂ O _{5 by} calcination

A small amount of sulfuric acid is used to adjust the pH of the aqueous phase solution in the range of 1.5-2.5, then the resulting product is heated above 90 ° C, held for 60-120 minutes and filtered, the precipitate is washed with water from a tap containing [ Na + K] ≤0.1 g / l, 3 times and each time the applied water is 30 ml, and the washing wastewater is combined with the liquid over the vanadium precipitate to obtain vanadium precipitation wastewater.

The precipitate of ammonium polyvanadate is dried, calcined and alloyed at 500-800 ° C to obtain V ₂ O ₅ and the composition of the obtained V ₂ O _{5 is} analyzed.

(5) Wastewater treatment

A low-water lime milk is prepared, vanadium precipitation is added to the wastewater to adjust the pH of the solution in the range of 9.5-11 and filtered. In the filtrate, the pH is adjusted in the range of 5-7 with diluted sulfuric acid to obtain circulating water as the washing water for the leach residue in the next cycle. The neutralized residue obtained after filtration is used as starting material for the extraction of Mn.

(6) Organic phase regeneration

The organic phase containing a cation such as Mn ²⁺ is reused after reversible extraction with a 2.5 M sulfuric acid solution. After 10 cycles, the organic phase is reversibly extracted with 6N hydrochloric acid, in addition to a 2.5 M solution of sulfuric acid, and washed with diluted sulfuric acid to remove Cl ^- and then the extraction agent is returned to the system. The solution obtained by the reversible extraction with hydrochloric acid and the solution obtained by the reversible extraction with sulfuric acid are treated separately. When Mn in the reversible extraction solution accumulates to some extent, the reversible extraction solution interacts with the neutralization residue of the wastewater to recover Mn.

The above steps (2) to (6) are repeated, 1000 g of the firing product is used in each cycle, the liquid-solid ratio for each cycle is 2: 1, vanadium is not precipitated after leaching in the first cycle, the leaching product is used to prepare the suspension in a second cycle to increase the concentration of vanadium in the leachate; then, during leaching in each of the remaining cycles, water for washing the remainder of the last cycle is used in stage (2) and the missing part is supplemented with circulating water; circulating water is used to wash the residue and supplement the missing part with clean water. Carry out 51 cycles and do not unload wastewater containing ammonia nitrogen from the system.

Excluding the first cycle without vanadium precipitation, the maximum value, minimum value, and average value of the extraction rate in the remaining cycles are shown in Table 10; the maximum value, minimum value and average value for the chemical composition of the product V ₂ O ₅ in the remaining cycles are shown in table 11; and the maximum value, minimum value and average value for the composition of the circulating water after the circulation treatment for the remaining cycles are shown in table 12.

Table 10. The rate of extraction of vanadium in the circulation method (%) Procedure Pretreated starting material Leaching Extraction Vanadium precipitation Removal of ammonia by calcination Total extraction speed Minimum 89.43 97.38 98.30 Maximum 98.50 92.78 98.14 99.29 97.00 83.89 Average 90.97 97.73 98.76

The extraction rate of the pre-treated starting material and the removal of ammonia by calcination in the above table are obtained from long-term industrial production data.

Based on table 10, it can be noted that the total average rate of extraction by the method of the invention of V ₂ O ₅ from vanadium slag reaches 83.89%.

Table 11. The main components of the product V ₂ O ₅ obtained by the circulation method (%) Position V ₂ O ₅ Mn Mg Ca TFe P S Si Na ₂ O + K ₂ O Minimum 99.09 <0.01 <0.01 <0.01 <0.01 0.02 0.01 <0.01 0.19 Maximum 99.66 0,07 0.01 0,03 0,03 0,03 0,03 0.01 0.33 Average 99.30 0,03 0.01 0.02 0.02 0,03 0.02 0.01 0.25

Table 11 demonstrates that the vanadium product obtained by this method is of good quality and complies with Chinese National Standard No.GB3283-87.

Table 12. The main components of the circulating water (g / l) Position Mn Mg NH ₄ ⁺ Na + K Ca SO ₄ ^2- P Si Al TFe TCr Minimum 0.23 0.25 2.49 0.21 0.42 11.23 <0.005 Maximum 1,56 1,53 4.84 0.35 0.62 21.84 Average 0.84 0.84 3.57 0.27 0.51 16.11 <0.005

Based on table 12, it can be noted that after 51 cycles of wastewater circulation, various impurity ions have no tendency to accumulate, and the circulation and reuse of vanadium extraction wastewater is realized at a low price, where K and Na are mainly present from the starting vanadium substance slag, and the amount of K + Na in the circulation water stabilizes within 0.2-0.4 g / l and does not increase after 51 cycles.

Claims (11)

1. The method of producing vanadium oxide using extraction, which includes the following stages:
but. mixing the vanadium-containing substance with the additive to obtain a mixed substance, where the additive is CaO or limestone and the amount of the additive has a mass ratio of CaO / V ₂ O ₅ in the mixed substance equal to 0.5-1.4: 1;
b. calcining the mixed substance at 860-950 ° C in an oxidizing atmosphere for 60-240 minutes to obtain a calcination product;
from. adding water to the calcined product to prepare the suspension, stirring and slowly adding a solution of sulfuric acid to leach the suspension with pH adjustment in the range of 2.5-3.5;
d. removal of the residue after leaching to obtain the leach product, the effect on the leach product of the P-removal treatment and Ca-removal treatment to obtain a mass ratio of total V to P in the leach product ≥1000 and [Ca ^2- ] in the leach product ≤0.05 g / l, washing the residue with circulating water to obtain the washing water used to prepare the suspension in the next leach;
e. the effect of extraction on the leachate after P-removal and Ca-removal using an extraction agent that is saponified with ammonia, and then the separation of the aqueous phase and the organic phase, and the mass ratio of NH ₃ / Mn in the aqueous phase is controlled in the range of 0.6- 2000: 1, using an extraction agent capable of extracting Mn ²⁺ , Mg ²⁺ and Fe ³⁺ at a pH of 2-5;
f. adjusting the pH of the aqueous phase with sulfuric acid in the range of 1.5-2.5, heating to a temperature of 90 ° C to the boiling point, keeping at this temperature for 30-120 minutes, filtering and washing, and drying the precipitate to obtain ammonium polyvanadate, exposing ammonium polyvanadate to calcination to remove ammonia to produce V ₂ O _5; or reducing ammonium polyvanadate to produce V ₂ O ₃ ; and
g. the removal of impurities P, Mn and Mg in the wastewater formed in stage f to obtain concentrations of Mn ²⁺ and Mg ²⁺ lower than 5 g / l, respectively, and a concentration of P lower than 0.005 g / l, to obtain circulating water and the return of the circulation water to stage c for suspension and to stage d to wash the residue, where the solid starting material used in the above stages has a total amount of alkali metal of not more than 0.3 wt.%, and the total amount of Cl ^- and NO ₃ ^- not more than 0.1 wt.%, and the liquid starting substance used for you in the above steps, has a total amount of alkali metal of not more than 0.1 g / l, and the total amount of Cl ^- and NO ₃ ^- is not more than 0.1 g / l. 2. The method of producing vanadium oxide according to claim 1, in which the mixed substance obtained in stage a has a particle size of 0.1 mm or less. 3. The method of producing vanadium oxide according to claim 1, wherein in step c, the calcined product is cooled and sprayed to 0.18 mm or less before preparing the suspension. 4. The method of producing vanadium oxide according to claim 1, wherein in step c, the concentration of the sulfuric acid solution is 10-75 wt.%, The leaching temperature is 10-58 ° C and the leaching time is 30-90 minutes 5. The method of producing vanadium oxide according to claim 1, in which the circulating water obtained in stage g is returned to stage d to wash the residue to obtain washing water, the washing water is returned to stage c for leaching and suspension, if the washing water is insufficient, apply circulation water to replenish. 6. The method of producing vanadium oxide according to claim 1 or 5, in which, in step c, the mass ratio of the total amount of water for preparing the suspension for the calcination product is 1.5-4: 1. 7. The method of producing vanadium oxide according to claim 1, in which during washing the residue, the number of washes is 5-7 times, and the amount of water used for each washing is 20-35 wt.% Of the residue, counting on a dry basis. 8. The method of producing vanadium oxide according to claim 1, wherein in step e, the extraction agent is at least one of bis (2-ethylhexyl) phosphate, mono (2-ethylhexyl) -2-ethylhexylphosphonate and bis- (2,4,4-trimethylpentyl) hypophosphoric acid. 9. The method of producing vanadium oxide according to claim 1, wherein in step e, the extraction agent is pre-saponified with ammonia so that the raffinate has a pH of 2.8-3.8. 10. The method of producing vanadium oxide according to claim 1, in which at the stage e the extraction conditions provide a mass ratio of NH ₃ / Mn in the aqueous phase in the range of 2-10: 1. 11. The method of producing vanadium oxide according to claim 1, wherein in step e, the organic phase is reused after regeneration with a 2-3 M sulfuric acid solution and then saponified with ammonia.

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