RU2325327C1 - Method of molybdenum extraction - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method comprises the extraction of molybdenum in sulphide form from water multicomponent solutions by the way of sodium sulphide loading to original solution, subsequent solution treatment with sulphuric acid up to pH = 2.5-3 and precipitation of molybdenum sulphide. beforehand sodium benzoate is added to original solution, its mole ratio to molybdenum salt is not less than 1:1. Sodium sulphide consumption must be not more than 100% of amount stoichiometrically necessary for molybdenum trisulphide precipitation.

EFFECT: decreasing of consumption.

2 cl, 1 tbl, 1 ex

Description

The invention relates to hydrometallurgy of rare metals, and in particular to methods of concentration and purification of molybdenum from aqueous multicomponent solutions.

In the hydrometallurgical technologies of non-ferrous and rare metals, methods of their concentration, preliminary pulp pretreatment, and deposition of these metals from aqueous solutions in the form of sparingly soluble sulfides are widely used (S.S. , Yekaterinburg, GOUUGTU UPI, 2002, S. 671-694) or (I. D. Reznik, S. I. Sobol, V. M. Khudyakov. Cobalt, vol. 2, M .: Mechanical Engineering, 1995, S. 161 -176) or (A.N. Zelikman, O.E.Krein, G.V. Samsonov. Metallurgy of rare metals, M.: Metallurgy, 1978, S. 47).

A common disadvantage of the known methods for the deposition of non-ferrous and rare metals in the form of sulfides is the dependence of their deposition and selectivity of extraction on the compositions of the initial solutions, namely, the presence of metal impurities and anions in them, which during the deposition can co-precipitate with the target metal, or due to complexation of the target metal with anions significantly affect its deposition. To destroy these complex compounds, a significant increase in the consumption of the sulfidizing reagent is most often required.

Known methods for the separation of molybdenum in the form of sulfide from multicomponent aqueous solutions (US patent 4423013, 1983 and patent FR 2404601, 1979). Both of these methods are difficult to implement and require a large consumption of sulfidizing reagents.

Of those described in the literature, the closest to the claimed object is a widely used in industrial practice method for the extraction of Mo in the form of Mo trisulfide from aqueous multicomponent solutions containing, along with Mo, impurities of certain metals (tungsten, silicon) and non-metals (sulfur, phosphorus, fluorine). The method consists in that the initial solution introduced sulphidizer reactant (Na ₂ S or NaHS), c followed by treatment (acidification) solution of mineral acid (HCl, HNO _3, H ₂ SO ₄₎ to a pH in the range 2,5 3.0. At this pH, Mo is precipitated in the form of sparingly soluble molybdenum trisulfide, which is separated from the liquid phase (mother liquor), for example, by filtration and sent for further processing by known methods (A.N. Zelikman, V.E. Krein, G. V. Samsonov. Metallurgy of rare metals. M.: Metallurgy, 1978, S. 47-49).

In the known method sulphidizer-adding reagent (the most common sulfide or sodium hydrosulfide) at the source of molybdenum salt solution (in this case sodium molybdate) is formed sulphosalts Na ₂ MoS ₄ by reacting

Upon subsequent acidification of the solution to pH 2.5-3.0, the Na ₂ MoS ₄ sulfosol is destroyed with the release of sparingly soluble molybdenum trisulfide by the reaction:

Na ₂ MoS ₄ + 2HCl = MoS ₃ + ↓ 2NaCl

Along with Mo, a certain amount of sulfides is also present, which are present in the solution of impurity metals, for example, tungsten in the form of its trisulfide, which necessitates an increase in the consumption of the sulfidizer for the deposition of Mo. A higher consumption of precipitant, leading to the precipitation of impurities, is also required in the presence of fluorine ions in the solution, forming strong oxyanions (MoO ₃ F) ^- .

The disadvantages of the described method are the relatively high consumption of the sulfidizing reagent, which, for the above reasons, exceeds 100% of the stoichiometrically necessary for the deposition of MoS ₃ , and the associated relatively low quality of the sulfide concentrate obtained in terms of its molybdenum content due to the coprecipitation of impurity metals from Mo. At the same time, a decrease in the consumption of the sulfidizer less than 100% of the stoichiometrically necessary leads to a significant underdeposition of Mo in the form of sulfide.

The aim of the present invention is to reduce the consumption of the reagent-sulfidizing agent during the deposition of Mo from multicomponent solutions while improving the quality of the MoS ₃ concentrate in the content of Mo and ensuring a high percentage of its recovery in precipitates.

This goal is achieved due to the fact that sodium benzoate is preliminarily introduced into the initial multicomponent solution of Mo, while the consumption of the sulfidizing reagent is ensured at a level not exceeding 100% of the stoichiometrically necessary for the deposition of MoS ₃ .

Sodium benzoate is introduced into the initial solution in an amount providing a molar ratio of sodium benzoate to the molybdenum salt in the solution of at least 1: 1.

The consumption of the sulfidizing reagent for the deposition of Mo is provided in the range of 80-100% of the stoichiometrically necessary for the deposition of molybdenum trisulfide.

Example.

In the initial multicomponent solution of the composition, g / l: molybdenum - 3.1, tungsten - 10.4, sodium sulfate - 145, fluorine - 0.8 with pH 7.5, sodium benzoate was added in the form of an aqueous solution with a concentration of 300 g / l in an amount providing a ratio of sodium benzoate to sodium molybdate in the initial solution equal to 1: 1. Then, sodium sulfide was added to the resulting solution in the form of a solution with a concentration of 300 g / l in an amount corresponding to 100% of the stoichiometrically necessary for the precipitation of MoS ₃ . 92% N ₂ SO _{4 was} poured into the resulting solution until the pH of the solution was 2.8.

The resulting pulp was heated to T = 95 ° C and agitated at this temperature for 1 hour. The pulp obtained after agitation was filtered through a double layer of a filter cloth (1st layer - belting, 2nd layer - dense lavsan). The MoS ₃ precipitate obtained on the filter was washed with hot water (T = 50 ° C) at a water flow rate of 3 kg / kg of wet sediment. Then the precipitate was collected and dried to constant weight, after which the MoS ₃ concentrate was analyzed for the content of Mo and basic impurities.

The results of an example implementation of the proposed method are summarized in Table 1.

In addition, this table provides data on the implementation of the method from a solution of the above composition depending on the ratio of sodium benzoate to sodium molybdate and on the consumption of the sulfidizing reagent.

Table 1 Experience number The molar ratio in solution of C ₆ H ₅ COONa / Na ₂ MoO ₄ The consumption of Na ₂ S,% of stoichiometry to MoS ₃ Extraction of Mo to precipitate MoS ₃ The composition of the concentrate MoS ₃ ,% dry sediment Note Mo W The amount of impurities one 0 120 97.4 48.3 2,5 3.4 Known method 2 0.5: 1 one hundred 98.3 48.9 1.4 2.2 The proposed method 3 1: 1 one hundred 98.6 49.6 0.2 0.8 four 2: 1 one hundred 98.4 49.5 0.25 1,0 5 1: 1 70 92.2 49.0 1,1 2.0 6 1: 1 80 97.8 49.8 0.15 0.4 7 1: 1 90 98.0 49.5 0.13 1,0 8 1: 1 one hundred 98.6 49.6 0.2 0.8 9 1: 1 110 98.6 48.8 1.8 2,4

As can be seen from the above table, the implementation of the proposed method in comparison with the known (experiment 1, table 1), allows to reduce the consumption of sulfidizing reagent up to 80-100% of the stoichiometrically necessary for the deposition of MoS ₃ while improving the quality of the molybdenum concentrate (i.e. increasing Mo content and decreasing the concentration of impurities in it while ensuring high Mo recovery in sediment). In this case, the best results from the implementation of the proposed method are achieved when the molar ratio of the sodium benzoate additionally added to the initial solution to the molybdenum salt in the solution is set to at least 1: 1 (experiments 3 and 4 of Table 1) and the consumption of the sulfidizing reagent is within 80-100% of the stoichiometrically necessary for the deposition of molybdenum trisulfide. Outside of the claimed intervals of these distinctive features, there is a decrease in the Mo recovery in the precipitate of its trisulfide. Thus, if the molar ratio of sodium benzoate to the molybdenum salt in the solution is less than 1: 1 (Experiment 2 Table 1), then a reduction in the quality of the concentrate MoS ₃ by increasing the coprecipitation of impurities.

The completeness of molybdenum extraction in the precipitate in the case of using a sulfidizing reagent in an amount of less than 100% of the stoichiometrically necessary for the formation of Mo8z is explained by the fact that in the presence of sodium benzoate, molybdenum oxo sulfides MoO _x S ₃ -x are formed and also precipitate.

At the same time, if the consumption of the sulfidizing reagent is less than 80 of the stoichiometrically necessary for the deposition of MoS ₃ (experiment 5 of Table 1), then there is a decrease in the extraction of molybdenum in the precipitate with a slight decrease in the quality of the concentrate. On the other hand, if the indicated consumption of the sulfidizing reagent is more than 100% of the stoichiometrically necessary for the deposition of MoS ₃ , then the quality of molybdenum trisulfide decreases due to an increase in the degree of impurity deposition into the precipitate.

Claims (2)

1. The method of extraction of molybdenum from aqueous multicomponent solutions in the form of sulfides by introducing sodium sulfide into the initial solution, followed by treating the solution with mineral acid to a pH of 2.5-3 and isolating a precipitate of molybdenum sulfide, characterized in that sodium benzoate is preliminarily introduced into the initial solution the molar ratio to the molybdenum salt in the solution is not less than 1: 1, while the sodium sulfide consumption is ensured at a level not exceeding 100% of the stoichiometrically necessary for the precipitation of molybdenum trisulfide, with leduyuschey treatment with sulfuric acid. 2. The method according to claim 1, characterized in that the consumption of sodium sulfide is provided in the range of 80-100% of the stoichiometrically necessary for the deposition of molybdenum trisulfide.