RU2479652C1 - Electrochemical processing method of metal wastes of tungsten-copper alloy wastes - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention refers to regeneration of secondary metal-bearing raw material, including to electrochemical processing of metal wastes of tungsten-copper alloys containing 7-50% Cu. The above method involves anodic oxidation of wastes in 10-15% of ammonia solution under action of direct current. At that, the oxidation process is performed with addition to the solution of 0.1-0.5 M NaOH or 0.1-0.5 M KOH at current density of 1000-3000 A/m².

EFFECT: improvement of metal extraction at minimum electric power consumption and effective separation of tungsten and copper.

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Description

The invention relates to the recovery of secondary metal-containing raw materials, in particular to the processing of metal waste from W-Cu alloys.

Involvement in the factory practice of the regeneration of various types of non-ferrous and rare refractory metal wastes is an important scientific and technical task. This is due to the limited raw material base of rare metals and the possibility of achieving sufficiently high indicators in the processing of secondary raw materials (extraction of valuable components, minimization of capital costs, etc.)

In general, the technology for processing tungsten-containing metal wastes (including carbide) is based on combined pyro- and hydrometallurgical processes, such as: firing, leaching, liquid extraction, etc. [A.N. Zelikman. Metallurgy of refractory metals. M.: Metallurgy, 1986. 440 p.].

With regard to the disposal of tungsten metal waste, the use of electrochemical methods based on the anodic oxidation (dissolution) of waste under the influence of various forms of electric current is especially promising. These methods provide high extraction of valuable components and the quality of the resulting product. So, in the RF Patent No. 2340707 “Method for the electrochemical processing of tungsten or rhenium metal wastes”, the technology of these types of metal wastes in ammonia electrolytes under the influence of a symmetrical alternating current of industrial frequency (analogue) is described. To ensure the necessary electrical conductivity of the system, the ammonia electrolyte is preliminarily held in a magnetic field with a strength of> 600 Oe for 24-48 hours.

Under these conditions, an increase in the electrical conductivity of the ammonia solution by more than 50% is achieved. This allows you to reduce the duration of the initial stage of the electrochemical storage redistribution from 24 to 10-12 hours. The limiting moments of the described process are as follows: this is a relatively low degree of increase in electrical conductivity (~ 50%), and a rather high duration of such preliminary processing.

The closest technical solution is the “Method of processing metal tungsten waste” (RF Patent No. 1794108, BI No. 5 of 02/07/1993). According to this method, the processing of tungsten metal waste is carried out in an ammonia electrolyte under the influence of a constant electric current with a force of up to 1 mA and above. To ensure the necessary electrical conductivity of the system, special additives, for example, triethanolamine, are introduced into the electrolyte. The limitations of this method are the use of organic additives of triethanolamine, which are not typical for hydrometallurgical processes of rare metals processing. In addition, these additives can adversely affect the deposition of ammonium paratungstate during evaporation of ammonia solutions.

The problem to which the present invention is directed, is to create a method for the electrochemical processing of metal wastes of a tungsten-copper alloy in ammonia solutions, providing the necessary electrical conductivity of the system and separation of the extracted metals.

The technical result of the invention is to increase the extraction of tungsten and copper in commercial products up to 98-99%.

The technical result is achieved by the fact that in the method of electrochemical processing of metal waste of tungsten-copper alloys, including anodic oxidation in 10-15% ammonia under the influence of direct electric current, according to the invention, the process is carried out with the addition of 0.1-0.5 M NaOH or KOH at a current density of 1000-3000 A / m ² .

Figure 1 shows the dependence of the current efficiency on the current density, which shows that the optimal mode lies in the range of current density up to ~ 300 mA / cm ² .

The essence of the invention lies in the fact that to ensure the necessary electrical conductivity of the anodic oxidation (dissolution) system of metal waste of the tungsten-copper alloy, additives of NaOH or KOH are introduced into the initial ammonia solution.

Recommended electrochemical redistribution mode: NH ₄ OH solution 10-15% + 0.1-0.5 M NaOH or KOH, direct current, temperature 20-30 ° C, duration 2 hours, current density 1000-3000 A / m ² (fig. 1).

As can be seen from table 1, under these conditions, the current efficiency approaches 100%. In this case, tungsten passes into an alkaline solution, and copper by 50% in the precipitate in the form of Cu ⁰ due to the cathodic reduction of copper. It is important that upon boiling the obtained tungstate solution, that part of the copper that has passed into the solution is also reduced and precipitates in the form of Cu ⁰ .

Table 1 Current density, mA / cm ² Current strength, mA Dissolved alloy, Δ M, g Theoretical Δ M, g Current output,% one hundred 128 0.31 0.29 ~ 100 200 280 0.66 0.65 ~ 100 300 294 0.66 0.67 99.9 400 368 0.80 0.86 93.0 500 420 0.87 0.98 89.0

The resulting solutions of W (VI) can be sent, without any pre-treatment, to the precipitation of tungsten acid by a known reaction:

[Na (K) ₂ WO ₄ ] + 2HCl (HNO ₃ ) = H ₂ WO ₄ + 2NaCl (NaNO ₃ )

Thus, the patented process of anodic oxidation (dissolution) of tungsten-copper metal alloys in solutions of NH ₄ OH + Na (K) OH under the influence of direct electric current with a density of up to 3000 A / m ² with the separation of tungsten and copper, which becomes a precipitate in the form Cu ⁰ .

Example 1

W-Cu alloy waste containing 10% Cu enters the electrochemical processing. The mode of anodic oxidation (dissolution) of the alloy: a solution of 10% NH ₄ OH + 0.5 M NaOH, temperature 20 ° C, duration 2 hours, constant current density of 200 mA / cm ² , current strength 280 mA, the area of the dissolved sample 1, 40 cm ² , the volume of the leach solution obtained is 150 ml.

Under these conditions, 0.66 g of the starting alloy was dissolved. In this case, up to 50% of the Cu contained in the alloy passed into a solution in which 3.96 g / L W was dissolved. This product was boiled for 60 min to completely remove copper in the form of Cu ⁰ and increase the tungsten concentration in the solution to ~ 10 g / l H ₂ WO _{4 was} precipitated from this solution by the usual method of neutralization with mineral acid (for example, H ₂ SO ₄ ).

The recovery of W and Cu in commercial products amounted to 99.5%.

Example 2

W-Cu alloy waste containing 10% Cu enters the electrochemical processing. Anodic oxidation mode of the alloy: 10% NH ₄ OH + 0.5 M KOH, temperature 20 ° C, duration 2 hours, direct current density 300 mA / cm ² , current 295 mA, the area of the dissolved sample 1.5 cm ² . In total, 0.66 g of the alloy was dissolved and 120 ml of a solution containing 4.95 g / l W was obtained.

After boiling this solution and completely removing copper in the form of Cu ⁰ from the purified solution, H ₂ WO _{4 was} precipitated by the above procedure.

Extraction of W and Cu in commercial products amounted to 98.9%.

The above examples confirm the achievement of a positive effect when using the proposed technical solution with minimizing energy consumption. Figure 2 shows a schematic flow chart of the processing of these wastes according to the described method.

Claims (1)

A method for the electrochemical processing of metal waste of tungsten-copper alloys, including anodic oxidation of waste in a 10-15% ammonia solution under the influence of direct electric current, characterized in that the oxidation process is carried out with the addition of 0.1-0.5 M NaOH or 0.1-0.5 M KOH at a current density of 1000-3000 A / m ² .

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