RU2280088C2 - Method of extraction of molybdenum from the acid solutions - Google Patents

Abstract

FIELD: chemical industry; methods of extraction of molybdenum from the acid solutions.

SUBSTANCE: the invention is pertaining to the extraction of molybdenum from the acid solutions. The method provides for the mixing of the solution with the reactant, the mixture neutralization by then alkaline reactant, aging of the fine pulp at stirring action, the sedimentation and removal of the liquid phase. At that the treatment of the source solution is exercised with the phosphoric acid or its salts in the amount of 97-100 % to the necessary amount according to the stoichiometry in terms of molybdenum. The neutralization is conducted with the help of the alkali solution with pH = 2.0-3.0, keep the fine pulp at stirring action within 1.0-1.5 h, the sedimentation of the fine pulp conduct for 1.0-2.0 h. The liquid phase is removed by the decantation. After removal of the liquid phase the remained sediment is dissolved using the caustic ammonia solution up to the liquid state. The technical result of the invention is the high degree of extraction of molybdenum, reduction of the duration of molybdenum extraction from the acidic and the very acidic solutions, reduction of power input.

EFFECT: the invention ensures the high degree of extraction of molybdenum, reduction of the duration of molybdenum extraction from the acidic and the very acidic solutions, reduction of power input.

5 cl, 2 tbl, 17 ex

Description

The invention relates to the extraction of molybdenum from acidic solutions containing a mixture of nitric and sulfuric acid and molybdenum in a wide range (from 2 to 100 g / dm ³ ), as well as other impurities, and can be used to extract molybdenum from waste electric, electronic and hydrometallurgical productions.

The high melting point, low evaporation rate, heat resistance, and relatively high electrical conductivity led to the use of molybdenum in the manufacture of electric lamps and electric vacuum equipment. One of the earliest applications of pure molybdenum is the manufacture of light bulbs in which hooks supporting a tungsten filament are made from molybdenum wire. In the same area, molybdenum is used as a core for winding ("spiraling") tungsten wire.

After annealing the spirals, the molybdenum core is removed by dissolving in a mixture of sulfuric and nitric acids. The result is acidic solutions containing up to 300-500 g / DM ³ sulfuric acid (H ₂ SO ₄ ); 100-300 g / dm ^{3 of} nitric acid (HNO ³ ) and 180-300 g / dm ^{3 of} molybdenum.

To isolate molybdenum from such solutions, it is recommended to neutralize with ammonia water, followed by evaporation of the solution and crystallization of a mixture of ammonium nitrate, sulfate and molybdenum. By calcining this mixture at 500-600 ° C, molybdenum trioxide is obtained, which can be purified by dissolving in an ammonia solution with the release of ammonium paramolybdate (A.N. Zelikman. Metallurgy. M, 1970).

However, with this method, 85-90% of molybdenum is recovered, and the rest is in the mother liquor. The extraction of molybdenum from alkaline and acidic solutions with a relatively low molybdenum content (from 5 to 60 g / dm ³ ), as well as from waste from the hydrometallurgical production of molybdenum, is an urgent problem.

From an analysis of patent and technical sources, the most well-known methods for extracting molybdenum from acidic and alkaline solutions are: leaching, extraction and sorption.

The variety of forms of molybdenum in aqueous solution (simple and polyanions, oxycations, complex anions) makes it possible to extract molybdenum by almost all types of organic extractants:

- anion exchange extractants such as amines and quaternary ammonium bases;

- "neutral" extractants, which include tributyl phosphate, alcohols, ethers, ketones;

- cation exchange extractants such as alkylphosphoric acids.

The use of extraction in molybdenum technology is very promising. The advantages of the process compared to ion-exchange sorption on resins are their greater selectivity (it is possible to selectively extract molybdenum in the presence of high concentrations of acid anions), as well as the applicability of the process for diluted and molybdenum-rich solutions. It is advisable to use sorption at relatively low molybdenum contents - 5-15 g / dm ³ .

A technical solution is known, the essence of which is that after the conversion of molybdenum to the form of the thiocomplex by treating the initial solution with a sulfide-containing reagent, it is sorbed on a weakly basic anion exchange resin, and desorption from the anion exchange resin is carried out by the action of an alkaline solution of ammonia, soda, caustic alkali at a temperature of 35-60 ° C.

During the extraction of molybdenum, dosed amounts of a sulfidizing reagent (sodium or ammonium sulfide or bisulfide) are added to the sodium or ammonium tungstate solution containing molybdenum to convert the molybdenum into the form of the [MoS ₄ ] ^2- thiocomplex, if necessary (if the pH of the solution exceeds 10.3 ) the pH is adjusted to 8.3-10.3 and the solution thus prepared is passed through a jacketed column filled with a weakly basic anion exchanger. After saturation with molybdenum, the column is washed with water, the jacket is supplied with hot water or steam so that the temperature of the contents of the column is 35-60 ° C, and an aqueous solution of an alkaline ammonia or soda reagent is passed through the column. At the end of the desorption of molybdenum, the supply of hot water or steam is turned off, the anion exchange resin in the column is washed with water and again used to extract molybdenum. Desorbate can be directly sent to molybdenum production, as well as processed separately by known methods (RF Patent No. 2048560).

The main disadvantages of this technical solution include:

- the complexity of the hardware design of the process;

- the impossibility of using it to extract molybdenum from acidic solutions;

- in the process of molybdenum extraction, hydrogen sulfide is formed, which negatively affects the environment, and also requires additional measures to ensure the safety of staff.

Depending on the pH of the initial solution, molybdenum ions exist:

- higher than pH 7.5-7.0 (depending on the concentration of molybdenum in solution) only in the form of molybdate ions MoO ₄ ^-2 ;

- at a pH of less than 2.5, the formation of cationic complex ions in equilibrium with anionic forms begins;

- after the isoelectric point (pH less than 1.0), molybdenum is in solution mainly in the complex cations MoO ₂ ⁺² , Mo ₂ O ₅ ⁺² , Mo ₃ O ₈ ⁺² .

From the actual pH of the stock solution, i.e. alkalinity or acidity, as well as the content of molybdenum in it, depends on the choice of method for extracting molybdenum from solution.

Known RF Patent 2195510 "Method for the extraction of molybdenum from acidic solutions", including multistage extraction with an organic extractant and multistage reextraction with an ammonium-containing solution, the extraction being carried out when the extractant is saturated with molybdenum 90-95% of theoretical, followed by two-stage washing of the extract, and ammonium sulfate extraction solution at equilibrium pH 4-6, regulated by feeding the stripping agent in parts at several stages of stripping.

Washing of the extract with a molybdenum content of about 30 g / dm ^{3 is} carried out with a solution of sulfuric acid with a concentration of 0.3-0.5 mol / l after reextraction with a sulfate-ammonia solution until a pH of 1-2 is created in the equilibrium washing solution.

Washing was carried out in several stages with different amounts and concentrations of sulfuric acid. At the first stage, when the ratio of organic and aqueous phases is O: B = 5: 1 with a solution of 0.5 mol / dm ^{3 with} sulfuric acid, then at the other stage with a sulfate-ammonia solution with a pH of 5-8 until a pH of 1- is created in an equilibrium wash solution 2 in order to create favorable conditions for the implementation of the process of re-extraction of molybdenum. Molybdenum was reextracted in countercurrent mode according to the Alders scheme at four steps.

The disadvantages of this technical solution include the complexity of the technological process, during the implementation of which it is necessary to change the parameters of the extraction process at each stage, strictly control the process both at the extraction stage and during the washing of the extract.

Extraction of molybdenum requires special technological equipment (columns for extraction and re-extraction of components).

A technical solution is known, which is protected by RF Patent No. 2091313, according to which molybdenum or tungsten is extracted from acidic solutions. The essence of the method: in a closed container carry out the reaction between urea and formaldehyde with a molar ratio of 1: (1.5-2). At the same time, a pH of 3-4.5 is created in the reaction zone by adding part of the initial solution containing molybdenum and / or tungsten. The reaction is carried out for 3-5 minutes with stirring, then, without stopping stirring, the resulting vapor-gas mixture is aspirated, which is passed through a filter with ammonium carbon dioxide, and then burned. To the urea-formaldehyde compounds remaining in the reaction mixture, the remainder of the initial solution is added with stirring and stirring is continued for 10-90 minutes. The precipitate containing molybdenum and / or tungsten is separated. The precipitate is mixed with a new portion of the stock solution. Stirred for 10-90 minutes. The precipitate is separated and treated again with the stock solution until it is completely saturated with molybdenum and / or tungsten.

The disadvantages of this method include: the use of formaldehyde, which requires additional safety measures, and the duration of the process when the content of molybdenum or tungsten in the solution is more than 15 g / dm ³ .

The closest to the claimed technical solution in essence and the achieved result is a technical solution protected by RF Patent No. 2213058. The invention relates to the extraction of molybdenum from molybdenum-containing acidic solutions, moreover, spent nitric sulfate solutions are used as the acidic molybdenum-containing solution - waste from electric lamp production. An iron-containing reagent in the form of metallic iron is introduced into an acidic molybdenum-containing solution in an amount of 50.0-90.0% of what is required by stoichiometry. After dissolution of the iron, an alkaline reagent is added to a pH of 2.9-5.0. The pulp is kept under stirring at 15-85 ° C and the indicated pH for 1-4 hours, then precipitated, filtered. The filtrate is washed and the molybdenum product is calcined at 650-800 ° C for 1-3 hours.

When processing strongly acidic molybdenum-containing solutions, which include waste electric lamp production, before the introduction of iron, the solutions are additionally treated with calcium carbonate in an amount of 20-100 g / DM ³ .

The disadvantages of the known technical solution are that the extraction of molybdenum does not exceed 95-96%, and at a pH of more than 3.0, a lot of iron impurities remain in the pulp, which are difficult to remove.

In addition, the calcination process increases energy consumption and also causes environmental degradation.

The technical problem solved by the claimed invention is:

- reducing the time of extraction of molybdenum from acidic and strongly acidic solutions;

- increasing the degree of extraction of molybdenum from nitric sulfate solutions in a wide range of molybdenum content in it;

- obtaining a liquid concentrate, which is a valuable semi-finished product for the production of a wide range of molybdenum compounds.

The technical result is achieved due to the fact that in the known method of extracting molybdenum from an acidic solution, including treating the initial solution with a reagent, neutralizing the mixture with an alkaline reagent, holding the pulp with stirring, precipitating and removing the liquid phase, the treatment of the initial solution is carried out with phosphoric acid or its salts in the amount of 97-100% required by stoichiometry in terms of molybdenum, the resulting mixture is neutralized to a pH of 2.0-3.0, after sedimentation, the liquid phase is decanted, and the obtained The first precipitate is dissolved in a solution of ammonia to a liquid state.

As salts of phosphoric acid, sodium or ammonium salts are predominantly used.

In addition, neutralization is carried out with a 25% ammonia solution, the sequential administration of several doses, the first dose being 90% of the calculated amount, and then with the same doses equal to 2-3% of the calculated value of the ammonia solution, and subsequent doses 2-3 % of the calculated amount of ammonia solution until a pH of 2.0-3.0 is reached, and at the dissolution stage, it is introduced at a volume ratio of precipitate and solvent 1: (0.95-1.1).

Extract pulp with stirring is carried out for 1.0-2.0 hours

After decantation of the liquid phase, the precipitate is dissolved in 25% ammonia solution with a volume ratio of 1: (0.95-1.1).

According to the results of the analysis of the prior art, no technical solutions have been identified that have the entire set of essential features of the proposed method, therefore it can be concluded that the claimed technical solution meets the patentability criterion of the invention of “novelty”.

Identified technical solutions only partially contain the claimed essential features, but do not possess the entire set of essential features of the claimed technical solution. So, phosphorus compounds are used as extractants for the extraction of molybdenum from solutions of its organic compounds. A known method of producing molybdenum products by mixing solutions of sodium molybdate and Fe ₂ (SO ₄ ) ₃ , followed by precipitation of the molybdenum product at pH 2.5-3.0, filtering, washing and calcining the precipitate (AN Zelikman. Molybdenum. - M .: Metallurgy, 1970, p. 150).

In the inventive method, only the entire combination of known and unknown essential features allows us to solve the problem and achieve a technical result.

The claimed technical solution does not explicitly follow from the prior art, since information on the chemistry of molybdenum in solutions indicates the diversity of its chemical properties. Molybdenum is characterized by disproportionation reactions. The coordination number of molybdenum can very easily change with a relatively small change in any process parameter, which greatly complicates the theoretical justification of the optimal parameters of the technology for producing molybdenum-containing products from solutions. To determine the optimal parameters of the technology for producing molybdenum products from molybdenum-containing acid solutions - production wastes - a large number of experiments are required, therefore, the optimal parameters of the claimed technical solution were identified after analyzing the results of numerous experiments, i.e. empirically.

Thus, the claimed technical solution meets the criteria of patentability of the invention "inventive step".

The use of phosphoric acid or its salts to extract molybdenum from acidic solutions as a reagent allows molybdenum to be extracted from solutions containing a wide quantitative range in the initial solution, i.e. from virtually any industrial waste with a high degree of extraction of 97.0-99.5% with the claimed ratios P: Mo = 0.97: 1.0 of the required stoichiometry.

With a ratio less than 0.97, as will be shown below, the degree of extraction decreases, and with a ratio of more than 1.0 it remains practically at the same level, and the consumption of the reagent — phosphoric acid and its even more expensive salts — increases.

The predominant use of sodium or ammonium salts of phosphoric acid is due to the fact that the resulting molybdenum compounds are easily processed into a wide range of industrial products of molybdenum chemistry.

The pH range of 2.0-3.0 is selected based on the stabilization of the composition of the precipitation and the reduction of impurities in them. At a pH of less than 2.0, the degree of extraction of molybdenum decreases, with more than 3.0, the amount of impurities in the finished product increases and the consumption of alkaline reagent to neutralize the suspension increases.

Conducting the neutralization of the suspension in several stages is optimal to ensure a narrow range of pH values, which must be controlled very accurately, because this stage is limiting.

An exposure of the pulp with stirring for 1.0-1.5 hours is necessary to equalize the concentration of molybdenum throughout the reactor volume. Less than an hour may not be enough for this, and more than 1.5 hours - the productivity of the process decreases.

When the pulp is deposited for less than 1 h, the degree of extraction of molybdenum decreases, and more than 2 hours, the productivity of the process decreases, almost without improving its results.

Dissolving the precipitate with a 25% ammonia solution makes it easy to pour the resulting valuable semi-finished product (the molybdenum content in it depends on the content in the initial solution and exceeds it by several times) in cans and can be sent to consumers who produce various molybdenum chemistry products from it.

Based on this, the amount of ammonia solution is desirable to have a minimum, only to ensure the fluidity of the concentrate. Based on the results obtained, the optimum ratio is established - precipitate / solvent. With less than 1: 0.95, there is a probability of obtaining a thick product, and more than 1: 1.1 - causes excessive dilution of the concentrate.

The essence of the chemistry of the process of molybdenum isolation can be represented by the reaction: xHNO ₃ , yH ₂ SO ₄ , 12H ₄ [Mo (SO ₄ ) O ₄ ] + H ₃ PO ₄ + zNH ₄ OH → (NH ₄ ) ₃ PO ₄ · 12MoO ₃ · 6H ₂ O + (12 + y) (NH ₄ ) ₂ SO ₄ + xNH ₄ NO ₃

The precipitate formed as a result of the reaction is a yellow, easily settled crystalline powder, poorly soluble in water, soluble in ammonia, alkalis, an excess of phosphoric acid.

Below are examples of the implementation of the proposed method, and for convenience in all examples, the composition of the initial solution is assumed to be the same. The content of components (in g / dm ³ ): molybdenum 20, sulfuric acid - 180, nitric 85, and the presence of impurities of iron, aluminum, nickel, bismuth, silicon, manganese, magnesium, calcium, copper and zinc in small quantities is also possible.

Example 1: Analysis of the initial molybdenum-containing solution was carried out by the photocoloritic method, the concentration of phosphoric acid by alkalimetric titration, its density using a hydrometer.

The calculation of the amount of phosphoric acid required for the precipitation of 3000 dm ^{3 of a} molybdenum-containing acidic solution was carried out according to the formula:

Mm - the mass of molybdenum contained in 3000 dm ^{3 of the} initial solution is calculated by the result of the analysis and is 0.02 · 3000 = 60 kg;

Mfk = 98 - molecular weight of phosphoric acid,

Sfc = 0.73 - its concentration (73%);

Mmm = 96 - molecular weight of molybdenum;

ρ _fc = 1.56 - the density of phosphoric acid (analysis results);

12 is the theoretical ratio of moles of molybdenum to moles of phosphoric acid.

Substituting these values in the formula, we obtain a stoichiometric amount of acid, which is equal to 4.48 DM ³ .

3 m ^{3 of a} molybdenum-containing solution is poured into a reaction apparatus with a volume of 4.2 m ³ equipped with a stirrer or a device for sparging. Turn on a stirrer or bubbler and load 4.48 dm ^{3 of} phosphoric acid. The neutralization of the reaction mass is started by loading into the apparatus initially 800 dm ^{3 of} 25% ammonia, after which the pH is checked using indicator paper. The pH was ~ 2.0. Then continued loading of 25% ammonia in portions of 20-25 dm ³ , each time measuring the pH of the reaction mixture, at pH 3.0, the loading of the reagent was stopped. In total, 900 dm ^{3 of} 25% ammonia were loaded. During the neutralization process, the reaction mass is heated to 50-60 ° C. After completion of the neutralization process, the reaction mass was stirred for 1.25 hours so that the mixture became uniform in composition. Then, the supply of cooling water to the jacket was turned on, and pulp sedimented for 2 hours. The resulting mother liquor in an amount of 3.8 m ³ and a residual content of 0.22 g / dm ^{3 was} decanted and sent to an ion exchange purification unit. The crystals obtained as a result of precipitation, the formula of which is (NH ₄ ) ₃ PO ₄ · 12MoO ₃ · 6H ₂ O, were dissolved with stirring in about 100 dm ^{3 of} 25% ammonia until the concentrate was liquid. The ratio of precipitate (104.8 DM ³ ) and solvent was: 1: 0.954. The resulting solution is a liquid concentrate with a molybdenum content of 180 g / dm ³ and is a valuable semi-finished product for the production of the entire spectrum of molybdenum compounds.

The degree of extraction of molybdenum (X%) was determined by the formula:

Sysh - the content of molybdenum in the initial solution, g / DM ³ ;

Misk - the volume of loading its initial solution, dm ³ ;

Smr - the content of molybdenum in the mother liquor, g / DM ³ ;

Mmr - the volume of the mother liquor in the reactor, DM ³ .

Example 2: It differs from example 1 in that the sodium salt of orthophosphoric acid (Na ₃ PO ₄ · 12H ₂ O) is used as a reagent for the precipitation of 3000 dm ^{3 of the} initial molybdenum-containing solution. The analysis of the reagent was carried out by known methods, as in example 1.

The calculation of the required amount of precipitating reagent was carried out according to the formula:

Mc is the mass of sodium phosphate 12-aqueous (sodium orthophosphate), kg;

Mm = 96 is the molecular weight of molybdenum;

12 - theoretical ratio of moles of molybdenum to moles of phosphoric acid;

Mms = 380 is the molecular weight of the sodium salt;

Sorn = 0.98 - concentration of sodium orthophosphate (according to analysis).

Further, all operations were carried out analogously to example 1. To neutralize the pulp to pH 3, 880 dm ^{3 of} 25% ammonia was consumed. The molybdenum content in the mother liquor was 0.25 g / dm ³ , and its amount was the same, i.e. 3800 dm ³ . 100 dm ^{3 of} 25% ammonia was added to the remaining precipitate (~ 96 dm ³ ), i.e. O: P-1: 1.04. The resulting liquid concentrate with a molybdenum content of 176 g / DM ³ .

The degree of extraction of molybdenum was determined by formula 2 and amounted to 98.4%.

Example No. 3: It differed from Example 1 in that ammonium phosphate 3-aqueous {(NH ₄ ) ₃ PO ₄ · 3H ₂ O} was used as the precipitating agent.

Accordingly, the molecular weight of three-water ammonium phosphate was introduced into formula 3, the concentration of the basic substance (according to the analysis) was 95%.

Further, all operations are as in example 1. 890 dm ^{3 of} 25% ammonia were used to neutralize the pulp to pH 3. The volume of the drained mother liquor was 3800 dm ³ , the molybdenum content in it was 0.24 g / dm ³ . 100 dm ^{3 of} 25% ammonia was added to the remaining precipitate (~ 100 dm); the precipitate / solvent ratio was 1: 1. The result was a liquid concentrate with a molybdenum content of 178 g / dm ³ .

The degree of extraction of molybdenum was 98.5%.

The remaining examples are shown in table 1. It also shows the main parameters of the first three examples of the implementation of the proposed method. In the examples in Table 1 (4-16), 73% orthophosphoric acid was used as the precipitating reagent, the amount of which was determined according to formula 1, and 90% of a 25% ammonia solution from the calculated value was initially introduced to neutralize with subsequent portioned administration the remaining amount to obtain a given pH of the pulp. The mother liquor in a volume of 3800 dm ³ (with the exception of examples 7 and 17) was decanted and the molybdenum content was analytically determined in it, then it was supplied to an ion exchange purification unit or drained into the sewer. The degree of extraction of molybdenum was determined by formula 2, and after dilution of the precipitate, the molybdenum content in the liquid concentrate was determined by analysis.

Table 1 The performance of the individual stages of the process No. p.p. P / mo ratio pulp pH Reagent consumption (dm ³ ) or kg Ammonia consumption (dm ³ ) for neutralization Pulp holding time (h) Precipitation Time (h) Qty Mo in the match. r-g / dm ³ Ammonia consumption for dissolution (dm ³ ) one 1,0 3.0 4.48 900 1.25 2.0 0.22 one hundred 2 1,0 3.0 13.46 880 1.25 2.0 0.25 one hundred 3 1,0 3.0 7.42 890 1.25 2.0 0.24 one hundred four 1,0 2,5 4.48 880 1.25 2.0 0.33 95 5 1,0 2.0 4.48 870 1.25 2.0 0.47 90 6 1,0 3,5 4.48 910 1.25 2.0 0.19 110 7 1,0 1,0 4.48 750 1,5 2.0 1,62 88 8 0.95 3.0 4.26 896 1.25 2.0 0.72 one hundred 9 0.90 3.0 4.03 885 1.25 2.0 2,36 90 10 1,1 3.0 4.93 904 1.25 2.0 0.915 one hundred eleven 0.97 2,5 4.36 890 0.75 2.0 0.90 95 12 0.97 2,5 4.36 890 1.75 2.0 0.40 one hundred 13 0.97 2,5 4.36 890 1,5 2,5 0.38 98 fourteen 0.97 2,5 4.36 890 1,0 2.0 0.40 one hundred fifteen 0.97 2,5 4.36 890 1,5 0.75 0.438 95 16 0.97 2,5 4.36 890 1,5 1,0 0.43 95 17 * 1,0 3.0 4.48 1440 1,5 2.0 0.23 150

Example 17 differs from previous examples in that the extraction of molybdenum from a strongly acidic solution is carried out by the claimed method from the initial solution of the prototype. The content of the components in it is the following, g / dm ³ : sulfuric acid 304, nitric acid 145, molybdenum 33.8, as well as the following impurities in terms of molybdenum: iron 7.6, nickel and tungsten - 0.13 each, the rest - minor amounts. Given the very strong acidity of the solution, in order to neutralize it to pH 3.0 it is necessary to spend 1440 dm ^{3 of a} 25% solution of ammonia, the process is carried out in an apparatus with a capacity of at least 5 m ³ and, accordingly, 4350 dm ^{3 of the} mother liquor are removed. The remaining process parameters are shown in table 1 and 2.

Quality indicators of examples 1-17 are shown in table 2.

table 2 Indicators / Experience No. The degree of extraction of Mo,% The ratio of sediment / solution g / DM ³ Mo content in mat. R-g / dm ³ Mo content in concentrate, g / dm ³ one 98.6 1: 0.954 0.22 180 2 98.4 1: 1,04 0.25 177 3 98.5 1: 1 0.24 178 four 97.9 1: 1,1 0.33 175 5 97.0 1: 1.12 0.47 171 6 98.8 1: 0.96 0.19 180 7 90.0 1: 1 1,62 172 8 95.4 1: 1 0.72 170 9 85.0 1: 1 2,36 140 10 94.2 1: 1.09 0.915 150 eleven 94.4 1: 1 0.90 172 12 97.3 1: 1.05 0.42 174 13 98.2 1,: 1,035 0.26 178 fourteen 98.0 1: 1.05 0.31 172 fifteen 97.2 1: 1 0.43 120 16 97.4 1: 1 0.40 182 17 99.1 1: 1.58 0.23 150

The analysis of examples and the final results of the implementation of the proposed method allows us to establish that the pH of the end of the deposition and the molar ratio P / Mo have the greatest influence on the degree of extraction of molybdenum from acidic solutions. The exposure time and sedimentation of the pulp also affect the final results, but to a lesser extent.

Thus, deviations of the pH value of pulp deposition from the claimed range (examples 6, 7) indicate that at pH <2.0 there is a noticeable decrease in the degree of extraction of molybdenum (90%) due to competitive complexation from sulfate ions. At pH> 3.0, the degree of release of molybdenum increases slightly, while almost all impurities are entrained in the precipitate along with molybdenum, which complicates the further processing of liquid concentrate. The consumption of 25% ammonia for neutralization also increases.

At pH 2.0 (example 5), the process indicators are higher than that of the prototype, but the molybdenum content in the mother liquor is slightly higher than desired.

With an increase in the molar ratio P / Mo in excess of 100% of the stoichiometric, i.e. excess phosphate (example 10), leads to the formation of another already more soluble phosphate complex and, accordingly, to a decrease in the degree of extraction of molybdenum.

The decrease in the ratio P / Mo <95% of the stoichiometric (example 9) leads to a decrease in the degree of extraction of molybdenum, because the amount of phosphorus is simply not enough for the formation of an insoluble precipitate (NH ₄ ) ₃ PO ₄ · 6H ₂ O · 12MoO ₃ .

When the ratio P / Mo = 95% of stoichiometry (example 8) shows that the degree of extraction of molybdenum is at the prototype level, although the process time is much shorter, but there is a lot of molybdenum in the mother liquor (0.9 g / dm ³ ).

Deviations of the claimed range of pulp holding time while stirring it (examples 11, 12) show that with holding less than 1 hour the degree of molybdenum extraction is insufficient, and with more than 1.5 hours it does not give a positive result, but only increases the duration of the process.

Deviations of the claimed range of time for the deposition of pulp (examples 13, 15) show that when the deposition time is more than two hours, the degree of extraction and other process indicators practically do not change, and the duration of the process increases. A deposition time of less than an hour affects the molybdenum content in the liquid concentrate (120 g / dm ³ ), i.e. process performance decreases.

Examples 2, 3 confirm the possibility of using sodium and ammonium orthophosphates for the extraction of molybdenum from acidic solutions - waste electric lamp production, and the results are almost similar to example 1, but their cost is higher than orthophosphoric acid.

An analysis of examples of the implementation of the proposed method, in which the process parameters are in the optimal range, shows that 95-110 dm ^{3 of} 25% ammonia is sufficient to dissolve the precipitate in order to bring it to a fluid flow consistency, i.e. when the ratio of sediment / solvent in the range of 1: (0.95-1.1).

The degree of extraction of molybdenum from the initial solution of the prototype by the present method is significantly higher, 99.1% - 95-95.5% of the prototype.

Compared with the known technical solutions, the claimed technical solution does not require bulky and complex equipment, because the whole process is carried out in one apparatus with a mixer. Analytical and technological control of the process of extracting molybdenum and obtaining liquid concentrate does not cause difficulties and does not require highly qualified personnel.

The advantages of the proposed technical solution include:

- a high degree of extraction (95.5-99%) of molybdenum from acidic solutions - waste from a number of industries;

- reducing the time of extraction of molybdenum from acidic and strongly acidic solutions;

- reduction in energy consumption, i.e. the technology is energy efficient;

- the versatility of the method suitable for the extraction of molybdenum from solutions, both poor and rich;

- obtaining a liquid concentrate - semi-finished product for the production of a wide range of molybdenum compounds.

The method was tested under industrial conditions at a pilot plant and at the end of this year it will be implemented at one of the electric lamp plants in Russia.

Claims (5)

1. The method of extraction of molybdenum from acidic solutions, including processing the initial solution with a reagent, neutralizing the mixture with an alkaline reagent, holding the pulp with stirring, precipitation, removing the liquid phase, characterized in that the processing of the initial solution is carried out with phosphoric acid or its salts in an amount of 97-100 % of the required stoichiometry in terms of molybdenum, the resulting mixture is neutralized to pH = 2.0-3.0, after precipitation the liquid phase is decanted and the resulting precipitate is dissolved with ammonia solution to liquid fluid state. 2. The method according to claim 1, characterized in that as the salts of phosphoric acid using sodium or ammonium salts. 3. The method according to claim 1 or 2, characterized in that the neutralization is carried out with a 25% ammonia solution by the sequential administration of several doses, the first dose being 90% of the calculated value of the ammonia solution, and the subsequent doses being 2-3% of the calculated amount ammonia solution to achieve a given pH. 4. The method according to claim 1, characterized in that the exposure of the pulp with stirring is carried out for 1.0-1.5 hours, and deposition for 1-2 hours. 5. The method of claim 1, characterized in that after decanting the liquid phase, the precipitate is dissolved in a 25% ammonia solution in a volume ratio of 1: (0.95-1.1).