RU2437946C2 - Procedure for processing vanadium containing raw material - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: procedure consists in preparation of water pulp from raw material, in introduction of sulphuric acid and anionite into it for leaching and in extraction of vanadium from pulp by sorption. Upon sorption saturated anionite is withdrawn and washed; vanadium is de-sorbed from anionite and regenerated anionite is introduced to the stage of leaching and sorption. Also, water vanadium pulp is prepared from vanadium containing raw material. As such there is used oxidised slag or slime at pH 11.5-7.5. Sulphuric acid is introduced into prepared water pulp at S:L=1:2 to pH 4.5-4.0. Vanadium is extracted from pulp by counter-flow sorption at pH 4.5-1.8 with following saturated ionite washing at drainage. Value of pH in pulp is maintained at 4.5-4.0 at withdrawal of saturated anionite, while at introduction of regenerated anionite - 2.0-1.8.

EFFECT: raised extraction of vanadium, elimination of upset of sparingly soluble forms of vanadium at moment of leaching, facilitation of completeness of sorbent saturation and minimal concentration of impurities on it, reduced consumption of sulphuric acid, reduced number of operations in process flow sheet.

2 cl, 4 tbl, 2 ex

Description

The invention relates to the processing of refractory vanadium-containing raw materials, namely the product of pyrometallurgical enrichment of vanadium-containing converter slags and sludges of ferroalloy production and can be used in the production of pure vanadium salts.

There is a method in which vanadium-containing converter slag is subjected to grinding, magnetic separation of metal inclusions, mixing with soda, oxidative calcination at high temperatures (750-850 ° C), followed by two-stage leaching of vanadium from oxidized slag with water and a solution of sulfuric acid, separation of vanadium compounds from the combined solutions by boiling with hot steam (Technological instruction TI 115-F-10-95. Production of vanadium pentoxide. OJSC Chusovskoy Metallurgical Plant, 1995).

The processing of converter slag by soda technology is characterized by the following disadvantages:

- low extraction of vanadium in the finished product, about 65%;

- low quality of the finished product (85-90% V ₂ O ₅ );

- the complex salt composition of wastewater and the inability to use them in a closed water circuit.

A known method, including crushing converter slag, magnetic separation of metal inclusions, mixing with a limestone reaction agent, oxidizing the charge at a temperature of 750-850 ° C until the elemental iron is completely burned out and vanadium is converted to a higher oxidation state, grinds the cinder to produce an oxidized vanadium water pulp weakly acidic, followed by two-stage leaching at pH 3,01-3,6 and a temperature 71-85 ° C, filtration and cake processing 3,5% H ₂ SO ₄ in the filter for extracting vanadium and slightly soluble forms you ELENITE it from the combined solutions to boiling steaming (RF patent №2041278, publ. 1995.08.09). The disadvantages of the method include:

- loss of vanadium in the pH leaching stage due to coprecipitation;

- low recovery from slag at the level of 75% and the low quality of the finished product and, as a result, the high content of vanadium (more than 3.0% V ₂ O ₅ ) in the waste sludge;

- high consumption of sulfuric acid - more than 1.5 t / t V ₂ O ₅ , a significant part of which is unreasonably lost on the site of neutralization of drainage water with lime milk;

- laborious filtering operation on special apparatuses (FPAKM);

- high energy consumption during heat deposition of manganese vanadates (8 tons of hot steam per 1 ton of V ₂ O ₅ );

- the bulkiness of the technological scheme associated with the separation of vanadium and manganese;

- loss of vanadium with drain water.

The closest in technical essence is the method of extraction of uranium, molybdenum, vanadium from ores (RF patent No. 2211253, publ. 2003.08.27). The method includes crushing ore, grinding and leaching of valuable components with mineral acid and subsequent sorption extraction of dissolved uranium, molybdenum and vanadium from the pulp. Before leaching, the crushed ore in the form of an aqueous pulp is oxidized by treatment with anion exchange resin in the OH form at a pH of 8.5-11.6, a redox potential of 50 to 150 mV at a temperature of 30-80 ° C, and leaching and sorption recovery are carried out by adding sulfuric acid to an oxidized pulp to a pH of 1.5-3.5 and anion exchange resin.

However, this method does not allow the oxidation of the vanadium compound (spinelide) and elemental iron in refractory slag converter with anion exchange resin in the OH form at pH 8.5-11.6 and ORP from 50 to 150 mV. Elemental iron and its compounds in the oxidation state (+2) at the stage of acid leaching go into solution and prevent the extraction of vanadium. In the known method, the oxidation of the components of the feedstock in the pulp is carried out at a pH of 8.5-11.6 and a redox potential of 50 to 150 mV and t ° 30-80 ° C with anion exchange resin in the OH form, and leaching and sorption extraction by adding to the oxidized sulfuric acid pulp to pH 1.5-3.5 and ion exchanger. Oxidation of converter slag and sludge from ferroalloy production is impossible under these conditions, and at the stage of pulp leaching and sorption, a large amount of iron is inevitably transferred to the solution, which leads to the precipitation of sparingly soluble vanadium salts at a pH of the most efficient dissolution and sorption process. An important point in the technology for extracting vanadium from converter slag and sludge is the burning of dispersed and korol iron and the conversion of wustite iron (FeO) to hematite (Fe ₂ O ₃ ), poorly soluble in dilute sulfuric acid. However, when firing slag and sludge, complete oxidation of iron to hematite is not achieved, and in the process of acid leaching there is a pH boundary of 1.8-2.0, after which the transition of iron into solution increases sharply.

An analysis of the above analogues and prototype revealed that none of them achieves high recovery while reducing the consumption of reagents, energy consumption and reduction of technological operations.

The technical result of the invention is to increase the extraction of vanadium, eliminating the precipitation of sparingly soluble forms of vanadium at the time of leaching, ensuring the saturation of the sorbent and minimizing the concentration of impurities on it, reducing the consumption of sulfuric acid, as well as reducing the operation of the technological scheme, namely the filtering operation.

The technical result is achieved in a method for processing vanadium-containing raw materials, including preparing aqueous pulp from the raw material, introducing sulfuric acid and anion exchange resin into it to leach and extract vanadium by sorption from the pulp, withdrawing saturated anion exchange resin, washing it, and desorption of vanadium from the anion exchange resin to the leaching and sorption stage, this aqueous vanadium pulp is prepared from vanadium-containing raw materials, which are used as oxidized slag or sludge at pH 11.5-7.5, the introduction of sulfuric acid in the prepared pulp is carried out at T: W = 1: 2 and up to pH 4.5–4.0, and vanadium is pulled out of the pulp by countercurrent sorption at pH 4.5–1.8, followed by washing of saturated anion exchange resin on drainage, and the removal of saturated anion exchange resin is carried out at pH 4.5-4.0, and when introducing the regenerated anion exchange resin, a pH of 2.0-1.8 is maintained.

In addition, the washing of saturated anion exchange resin is carried out at a content of 350-650 kg V ₂ O ₅ per ton of anion exchange resin with 1% sulfuric acid solution, and desorption is carried out with ammonium nitrate 150-200 g / l at a pH of 7.5-8.5 in solid phase mode and pH 4.5-5.5 in the liquid phase mode.

In the tail column, the pH is maintained by acidic anion exchange resin and sulfuric acid, and in the intermediate columns by sulfuric acid. The residence time of the pulp and anion exchange resin in each column is 1-2 hours. Anion exchange resin is discharged from the head column only after saturation of 350-650 kg of V ₂ O ₅ per ton of anion exchange resin. The tailpipe pulp is filtered, the sorption mother liquor is used at the stage of manganese precipitation in the form of high-purity manganese concentrate (VKM).

As follows from the existing level of technology, the processes of leaching and sorption of vanadium from aqueous pulps of oxidized slag or sludge depend on the pH of the acidic medium. An increase in pH leads to an increase in saturation of anion exchange resin, and a decrease in pH leads to an increase in the leaching of vanadium and iron into solution from oxidized slag or sludge. Simultaneously with an increase in the concentration of iron in solution, the formation of sparingly soluble vanadium salts increases. To eliminate this undesirable process, it is necessary to combine the leaching and sorption operations, the sorption of vanadium should be ahead of the leaching of impurities. This effect is achieved if the system is slag or slurry - solution - anion exchange resin moves from neutral to acidic environment. Under these conditions, the concentration of vanadium in the equilibrium solution will always be minimal, and an increase in the concentration of iron in acidic solution will not be so adverse. At present, vanadium-containing converter slags with a higher content of manganese compounds in comparison with previously processed slags are involved in acid processing. A significant part of sulfuric acid is spent on opening manganese and iron-containing compounds, the intensity and completeness of opening of the components depends on many factors, the main of which is the pH treatment of pulp.

In the proposed method, the opening of the beneficial component and its extraction on the anion exchange resin, moved countercurrent to the aqueous pulp, is carried out under conditions in which the iron is not yet converted into a solution of pH 1.8-2.0, and vanadium passes into the liquid phase with sufficient completeness and concentrates on sorbent. Preparation of vanadium water pulp from oxidized slag or sludge is carried out from pH 11.5-7.5 to pH 4.5-4.0 by treatment with an acid wash solution or sulfuric acid, and countercurrent sorption and leaching of vanadium at pH 4.5-1, 8. The withdrawal of saturated anion exchange resin from the pulp is carried out at a pH of 4.5-4.0, the introduction of the regenerated anion exchange resin for sorption is carried out at a pH of 2.0-1.8. The ion-exchange extraction of vanadium to anion exchange resin reduces the concentration of the useful component in the liquid phase and leads to an additional transfer of the useful component from oxidized slag or sludge to the solution.

The operation of preparing water pulp is advisable to carry out at the site of grinding and thickening to pH 4.5-4.0, and acid treatment in sorption columns at pH 4.5-1.8. The most preferred in the proposed method is to carry out sorption at high pH in the head, along the pulp, apparatuses with achieving maximum saturation of the sorbent with vanadium and a subsequent decrease in pH to the tail unit, which allows to achieve sufficient completeness of opening of the useful component and eliminates the possibility of precipitation of insoluble vanadium salts, and the pulp after the tail unit is filtered. The acidic mother liquor containing manganese is sent to an ozonation unit to recover chemical manganese dioxide (CDM), and the filter sludge is washed with a 3% sulfuric acid solution in circulation and used as intended. Regulation of the pH of sorption within the specified optimal limits on the cascade of columns can be achieved both by supplying sulfuric acid and introducing into the pulp an acid regenerated anion exchange resin, which is determined by the rate of anion exchange in the sorption-desorption – recharge system. The combination of leaching and sorption processes is carried out in anion exchange treatment apparatuses, where a constant pH is maintained in each apparatus.

Thus, in the proposed method, the most important and controlled parameters are the pH of the pulp to stabilize the vanadium compounds in the solution, as well as maintaining the required pH in the head and tail along the pulp of the ion treatment apparatus, the first of which determines the saturation of anion exchange resin, and the second determines the completeness of vanadium extraction from sludge or slag and the total consumption of the reagent.

The method is as follows.

The process of preparing water pulp is carried out on crushed slag or sludge with a particle size of 0.1 mm 100% at T: W = 1: 1.5 and pH 11.5-7.5 and treatment with acid to T: W = 1: 2 and pH 4 5-4.0. The initial pH values of the oxidized vanadium water pulp depend on the content of the reaction agent in the feedstock entering the stage of oxidative calcination. Anion exchange treatment is carried out with highly basic anion exchange resin according to a countercurrent multistage scheme, the residence time of the pulp and anion exchange resin at each stage is 1-2 hours, the sorbent content is maintained at 5-15% of the pulp volume. Countercurrent multistage sorption leaching of vanadium with the introduction of regenerated anion exchange resin, the withdrawal of saturated anion exchange resin is carried out in the range of pH 1.8-4.5. The separation of anion exchange resin is carried out on drainage nets with washing from the pulp of saturated anion exchange resin with a content of 350-650 kg of V ₂ O ₅ at the last stage with a 1% solution of sulfuric acid. The desorption of vanadium from saturated anion exchange resin (regeneration) is carried out with a solution of NH ₄ NO ₃ 150-200 g / l at pH 7.5-8.5 in solid phase, and at pH 4.5-5.5 in liquid phase mode, the first volumes of eluate, containing (NH ₄ ) ₂ SO ₄ are used at the recharge site, the eluate yield is 4.0-5.0 volume per volume of anion exchange resin, additionally recharging is carried out with a solution of 1% H ₂ SO ₄ volume per volume of anion exchange resin, followed by supply of regenerated anion exchange resin to sorption vanadium.

Example 1

Oxidized slag 100 g with a content of 13% V ₂ O ₅ was taken, pulp in water at T: W = 1: 2 and pH 8.5, then sulfuric acid was introduced into the oxidized aqueous pulp to pH 4.5-4.0 and loaded in sulphate form the anion exchange resin Ambersep 920 by volume at the rate of 10% per pulp volume. After that, with an interval of 1 hour, the pH of the pulp was reduced to 4.0; 3.5; 3.0; 2.5; 1.8 with stirring. Anionite from the head column was washed from the pulp on the drainage grid and sent to the desorption of vanadium, and the pulp from the tail column with a pH of 1.8 was filtered and washed with water. The mother liquor contained 0.05 g / l V ₂ O ₅ and 0.2 g / l Fe, insoluble sediment - sludge 76 g contained 1.6% V ₂ O ₅ . Vanadium recovery was 90.0%. After desorption, the V ₂ O ₅ content is 98.5%.

Example 2

Sludge 100 g with a content of 3.0% V ₂ O ₅ was taken, pulp in water at T: W = 1: 2 and pH 9.5, then sulfuric acid was introduced into the oxidized aqueous pulp to pH 4.5-4.0 and loaded in sulphate form the Ambersep 920 anion exchanger by volume based on 7% per pulp volume. After that, with an interval of 1 hour, the pH of the pulp was reduced to 4.0; 3.5; 3.0; 2.5; 1.8 with stirring. Anionite from the head column was washed from the pulp on the drainage grid and sent to the desorption of vanadium, and the pulp from the tail column with a pH of 1.8 was filtered and washed with water. The mother liquor contained 0.03 g / l V ₂ O ₅ and 0.1 g / l Fe, insoluble sediment - sludge 85 g contained 1.15% V ₂ O ₅ . Vanadium recovery was 71.0%. After desorption, the V ₂ O ₅ content is 98.0%. The data obtained (see table 1, 2) show that the extraction of vanadium by the proposed method has a higher degree (up to 80% from sludge and up to 90% from slag) in comparison with the known method. At the same time, the proposed method will reduce the consumption of sulfuric acid to 750 kg / t V ₂ O ₅ . The rationale for the boundary values of the parameters of the proposed method is presented in the drawing and tables 2, 3. The drawing shows the dependence of the iron content in the solution on the pH of the processing of slag or sludge. The obtained curve shows that in the range of pH 2.0-1.8, the degree of conversion of iron into solution is minimal, with a decrease in the pH of the acid treatment to 1.8, the overwhelming majority of iron remains solid, a further decrease in pH leads to its transition into the liquid phase of the pulp, which, in turn, causes the restoration of vanadium, which is not adsorbed on anion exchange resin. Thus, the presented graphical dependence shows that the minimum boundary value of the pH of the processing of slag or sludge is 1.8, which is also supported by the indicators obtained by modeling the scheme of countercurrent multistage acid-anion exchange treatment of pulp. The data presented in table 2 show that the extraction of vanadium from oxidized sludge confirms high results in the specified pH range. From the data in Table 3, the region of the boundary pH values of the output of saturated anion exchange resin is determined within the range of 4.5–4.0, the content of iron and manganese on the sorbent, respectively, does not exceed 0.1 and 10.0 kg / t of anion exchange resin, its saturation with vanadium is, respectively 350-650 kg / t. Raising the pH to 5.0, as well as lowering it to 1.0 at this stage, leads to a decrease in the concentration of vanadium on the sorbent and, in the latter case, to an increase in the iron content on the anion exchange resin.

Thus, it was shown that the region of the process of vanadium sorption, combined with its leaching from the solid phase, is in the range of pH 4.5-1.8, its lower boundary is determined by the minimum pH of 1.8, at which decrease an intensive transition begins iron in the solution, respectively, an increase in the consumption of sulfuric acid and an increase in the concentration of sulfate ions in the solution, the upper limit is determined by the optimal saturation of the sorbent with the lowest iron content on it, higher than pH 4.5, the concentration of vanadium on the anion exchange resin declining. For the preparation of oxidized vanadium pulp without the presence of anion exchange resin, the pH range is determined in the range of 4.5–4.0, the upper boundary value leads to a decrease in sorption due to the formation of an unsorbable supramolecular vanadium compound, the minimum leaching pH is in the above region of the highest high sorption recovery . The limits of pulp pH during the removal of a saturated sorbent and the introduction of regenerated anion exchange resin enter the pH range of the combined process 4.5–1.8; their values, respectively, are 4.5–4.0 and 2.0–1.8. The saturated sorbent is washed with a 1% solution of sulfuric acid to wash out the productive solution and remove impurities of iron and manganese. An increase or decrease in acidity leads to leaching of vanadium from anion exchange resin. To maintain the structure of the anion exchange resin, desorption is carried out by NH ₄ NO ₃ in the range of 150-200 g / l. The lower limit is determined by the inefficiency of desorption of vanadium from saturated anion exchange resin, and the upper limit is determined by the reagent consumption saving. Desorption in the solid-phase and liquid-phase modes ends with the crystallization of ammonium metavanadate, which, upon thermal decomposition, produces pure vanadium oxide (more than 99% V ₂ O ₅ ). Liquid phase desorption results in a purer vanadium oxide. The results of solid-phase and liquid-phase desorption of vanadium from ion exchanger are presented in Table 4, from which a high degree of desorption of 98.7% and high quality of ammonium metavanadate are visible due to the selectivity of the sorption process.

The results of leaching of vanadium from aqueous slag pulp combined with countercurrent sorption on anion exchange resin in the range of pH 4.5-1.8.

Test conditions: T: W = 1: 2, time - 60 min, temperature = 60 ° C, anion exchange resin - 15% volume.

Table 1 Columns Slag 16.8% V ₂ O ₅ , in solution 11.3 g / l V ₂ O ₅ V ₂ O Recovery ₅ % Consumption H ₂ SO ₄ kg / t V ₂ O ₅ No. p / p Characteristic pH The content of V ₂ O ₅ solution, g / l sludge,% anion exchanger, mg / g one head 4,5 5.17 5.96 650,0 60.3 - 2 interm. 4.0 4.03 4.7 498.0 63.7 300,0 3 interm. 3,5 0.59 3.2 465.0 71.0 400,0 four interm. 3.0 0.37 1.8 430.0 75,2 525.0 5 interm. 2.5 0.08 1,2 350,0 81.5 540.0 6 tail 1.8 0.74 1,0 120.0 90.7 750.0

The results of leaching of vanadium from aqueous slurry pulp combined with countercurrent sorption on anion exchange resin in the pH range 4.5-1.8.

Test conditions: T: W = 1: 2, time - 60 min, temperature = 60 ° C, anion exchange resin - 5-10% by volume.

table 2 Columns Sludge 3.4% V ₂ O ₅ , in solution 4.0 g / l V ₂ O ₅ V ₂ O Recovery ₅ % Consumption H ₂ SO ₄ kg / t V ₂ O ₅ No. p / p Characteristic pH The content of V ₂ O ₅ solution, g / l sludge,% anion exchanger, mg / g one head 4,5 4.0 3.0 350,0 15.0 100.0 2 interm. 4.0 3.3 2,4 270,0 20,0 250,0 3 interm. 3,5 2.0 2.0 250,0 30,0 300,0 four interm. 3.0 0.9 1.7 190.0 45.0 450,0 5 interm. 2.5 0.2 1,5 145.0 50,0 600,0 6 tail 1.8 0.3 1.05 100.0 80.0 750.0

Table 3 The dependence of the saturation of the sorbent with vanadium, iron and manganese on the pH of the acid-anion exchange resin pH of an acid anion exchange resin 5,0 4,5 4.0 3,5 3.0 2.5 2.0 1,5 1,0 The content of V ₂ About ₅ on the sorbent, kg / t 480 520 600 650 580 500 350 160 thirty The content of Fe on the sorbent, kg / t less than 0.1 less than 0.1 less than 0.1 0.1 0.1 0.1 0.1 1,5 10.1 MnO content on the sorbent, kg / t 1,0 2.1 5.2 7.1 8.0 9.0 10.5 13,2 14.1

Results of solid-phase and liquid-phase desorption from anion exchange resin Table 4 Desorption Type Saturated Anion Exchanger Desorbat Ammonium Metavanadate Pulp Stock solution Ammonium Metavanadate Ml volume V ₂ O ₅ g / kg dry. anion exchange resin V ₂ O ₅ , g Volume ml V ₂ O ₅ , g / l % PH Ml volume V ₂ O ₅ , g / l pH Weight MVA, g The content of V ₂ O ₅ % Exit, % Solid phase one hundred 350 17.5 200 82.0 93.5 7.5 200 1.05 8.2 23,23 75,5 99.1 one hundred 650 27.5 200 129.0 94.2 8.5 200 1.51 8.5 36.10 76.6 99.3 Liquid phase one hundred 350 17.5 1000 15.8 90.0 4,5 1000 1,50 8.5 23.10 77,2 98.2 one hundred 650 27.5 1000 25,4 92.4 5.5 1000 1,62 8.0 35.1 77.6 98.7

Claims (2)

1. A method of processing vanadium-containing raw materials, including the preparation of aqueous pulp from the raw materials, introducing sulfuric acid and anion exchange resin into it to leach and extract vanadium by sorption from the pulp, withdrawing saturated anion exchange resin, washing it, desorbing vanadium from anion exchange resin and introducing regenerated anion exchange resin to the leaching and sorption stage characterized in that the aqueous vanadium pulp is prepared from vanadium-containing raw materials, which are used as oxidized slag or sludge at pH 11.5-7.5, the introduction of sulfuric acid in the prepared aqueous the pulp is carried out at T: L = 1: 2 and to a pH of 4.5-4.0, and vanadium is extracted from the pulp by countercurrent sorption at a pH of 4.5-1.8, followed by washing of the saturated ion exchanger in the drainage, and the conclusion of the saturated anion exchanger is carried out at pH 4.5-4.0, and when introducing regenerated anion exchange resin, pH 2.0-1.8 is maintained in the pulp. 2. The method according to claim 1, characterized in that the washing of the saturated anion exchange resin is carried out when the anion exchange resin contains 350-650 kg of V ₂ O ₅ per ton of anion exchange resin with 1% sulfuric acid solution, and desorption is carried out with ammonium nitrate 150-200 g / l at a pH of 7.5-8.5 in solid-phase mode or at pH 4.5-5.5 in a liquid-phase mode.

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