Method for processing waste solid alloys

 

(57) Abstract:

The invention relates to hydrometallurgy of refractory metals and can be used in electrochemical recycling tungsten-containing hard alloy. The invention allows to increase the productivity of the electrolysis process, increase the output current, reduce reagent consumption and the improvement of sanitary and hygienic working conditions. Method for processing hard alloy includes anodic dissolution in the electrolyte on the basis of hydrochloric or sulfuric acid. This anodic dissolution is carried out in the mode of the asymmetric reversible current under the action of a direct electric current with a periodic switching of the current direction on the reverse, while the process is conducted at a concentration of hydrochloric or sulfuric acid 30-150 g/l, duration of the reverse currentarr=0,5-2, the relationCR/arr== 5-15, the forward current density jCR=1,0-5,0 kA/m2and the reverse current to direct jarr/jCR= 0.5 to 2.0, whereCRthe time of action of a direct current with;arr- the duration of the reverse current, s; jCRthe forward current density, kA/m2; jarrthe density of the reverse current, kA/mwho owano electrochemical recycling tungsten-containing hard alloy.

There is a method of refining alloys (RF patent 2044112, IPC725 With 1/00, publ. 01.07.93 year ), including conducting electrolysis in the electrolyte solution by passing a direct electric current with periodic switching directions on the reverse of the given potential difference, the strength of the reverse current set 1.1 - 10 times the current corresponding to the emission of the gas from the electrolyte, and lead the process when the value of the reverse current to reduce the rate of change of potential difference in the 10 - 100 times, then reduce the current to the value of the potential dissolution of electronegative impurities and switch the direction of current to direct upon reaching the thickness of the cathode layer value (0,05-0,5) L where L is the interelectrode distance.

This method cannot be used for recycling tungsten-containing alloys, since the tungsten from aqueous electrolytes electrochemically not allocated, furthermore, the method has a complicated instrumentation.

Closest to the claimed method is a method of anodic dissolution of waste carbide hard alloys of the type VK and TTK in electrolytes containing HNO3H2SO4or with Hcl and the A. A., Levin, A. M. , Bryukvin Century A. / Electrochemical processing of tungsten-containing carbide waste of hard alloys. // Non-ferrous metals. 1999. 8. S. 42-45.)

The disadvantage of the prototype is a low current output during anodic dissolution at a constant current (49-67% per WO3and on alternating sinusoidal current it is 20-25%, which is explained by the formation of oxide films, increasing the capacity of the dual electrode layer, and increasing the capacitive current component.

In half-wave mode of electrolysis in the electrolyte on the basis of HNO3the current output increases, however, the application of HNO3requires special equipment and is associated with the release of harmful nitrous gases.

Another disadvantage of the prototype is the high consumption of acid (350-400 g/l in the initial solutions) and reagent on the reverse (residual concentration of NGO3in cobalt solutions 320-350 g/l).

The objective of the proposed technical solution is to provide a method for recycling of solid alloys with high performance and low consumption of reagents, the improvement of working conditions.

The technical result consists in the intensification process by expanding on the, is that the known method of processing waste of hard alloys based on tungsten carbide, including anodic dissolution in the electrolyte on the basis of hydrochloric or sulfuric acid, according to the invention anodic dissolution is carried out in the mode of the asymmetric reversible current under the action of a direct electric current with a periodic switching of the current direction on the reverse, while the process is conducted at a concentration of hydrochloric or sulfuric acid 30-150 g/l, duration of the reverse currentarr= 0,5 - 2, the relation CR/arr= 5 - 15, the density of the forward current jCR= 1,0 - 5,0 kA/m2and the reverse current to direct jarr/jCR= 0.5 to 2.0,

where CRthe time of action of a direct current, with,

arr- the duration of the reverse current, with,

jCRthe forward current density, kA/m2,

jo6pthe density of the reverse current, kA/m2.

Experimentally determined optimal regimes of electrolysis and when performance is above or below concentrations, densities and duration of action forward and reverse currents and their relationship anode current output is reduced.

It is established that the increase in acid concentration leads to a decrease in the efficiency of the method is illustrated on a concrete example.

Example

Was studied the behavior of the alloy VK-15, having the following composition, %: W 85; 15.

As a source of reversible current was used appliance series RIT (made by and. C. the USSR 1458956, IPC7H 02 M 9/06, publ. 15.02.89 year) that allows you to adjust both direct and reverse current in a wide range of variation.

Anodic dissolution was carried out under the action of the reversible asymmetrical current in an aqueous solution of hydrochloric acid concentration of 50 g/l aqueous solution of sulfuric acid concentration of 50 g/l when the duration of the reverse current arr= 1, the relationCR/arr= 5, density direct current jCR= 5,0 kA/m2, the reverse current to direct jarr/jCR= 1.5 and room temperature.

When dissolved uses two electrodes of dissolved alloy. The discharge of cobalt ions on the cathode electrodes period elapses, because the hydrogen evolution overpotential on VK in acidic solutions is lower than the evolution overpotential cobalt, and therefore the cathode is allocated only to hydrogen.

When changing the current direction plentiful allocation of dissolved hydrogen on the electrode causes the Opera is concerned with the current output.

The magnitude of the output but current in hydrochloric acid under the conditions specified above, amounted to 99,28% (some other examples are given in table. 1 and 2, the values specified WITH theHCl,arrand jarr/jCRare optimal).

The use of the proposed method in comparison with the prototype will allow to improve the performance of anodic dissolution, to increase the anode current output, to use cheaper and safer electrolytes and reduce the consumption of reagents.

Method for processing waste of hard alloys based on tungsten carbide by anodic dissolution in the electrolyte on the basis of hydrochloric or sulfuric acid, characterized in that the anodic dissolution is carried out in the mode of the asymmetric reversible current under the action of a direct electric current with a periodic switching of the current direction on the reverse, the concentration of the hydrochloric or sulfuric acid equal 30-150 g/l, duration of the reverse currentarr= 0.5 to 2.0 s with respect toCR/arr= 5-15, the forward current density jCR= 1,0-5,0 kA/m2the attitude of the reverse current to direct jarr/jCR= 0.5 to 2.0, whereCRthe time of action of a direct current with;arr- the duration of the reverse that is

 

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