The method of extraction of gallium from powdered waste

 

(57) Abstract:

The invention relates to hydrometallurgy. To extract gallium from geliysoderzhaschih powdered waste carry out the decomposition of waste in the presence of an oxidant and electrochemical allocation of gallium at the cathode. For this decomposition is conducted in aqueous solution of a strong base in the presence of atomic oxygen generated in the anode section of the cell when the anode current density of 0.2 Dand1 A/cm2. The method allows to increase the degree of extraction of gallium and to reduce the number of technological operations. 1 PL.

The invention relates to methods for extracting gallium from semiconductor waste and can be used in the electronic industry, ferrous metallurgy and other industries engaged in the processing kalisoderjasimi raw materials.

The closest in technical essence is the method of extraction of gallium method of oxidation (O. E. crane. Waste scattered rare metals. M.: metallurgy, 1985, S. 46-47). This method produces oxidation of the powder gallium arsenide when heated in oxygen or air. The reaction begins at 300 to 400° C, the most complete passes at 1000° Obrazuyuschihsya gallate, sodium and electrochemically produce gallium.

The main disadvantages of this method are the low degree of extraction of gallium, because, as in the way the analogue is shielding the reaction products - oxide, gallium GA2ABOUT3formed on the surface of the original waste, the method consists of a large number of technological operations and at every possible losses.

The technical result of the present invention is to increase the degree of extraction of gallium and reduce the number of technological operations.

Technical result provided by the invention, is achieved in that in the method of extraction of gallium from geliysoderzhaschih powdered waste including waste decomposition in the presence of an oxidant and electrochemical allocation of gallium at the cathode, the extraction is carried out in the electrolytic cell with anode and cathode sections decomposition of waste in the anode section in an aqueous solution of a strong base in the presence of as oxidant atomic oxygen evolved at the anode when the anode current density of 0.2 Dand1 A/cm2.

Increasing the degree of extraction of gallium is because the oxidation of the feedstock is atomic oxygen, objecto, is a stronger oxidant than with molecular oxygen. Further, the reaction products containing gallium, constantly derived from the decomposition zone - anode section in the cathode section, with a recovery of gallium to metal. So it isn't shielding of the feedstock to the reaction products. When the anode density Dand<0.2 a/cm2oxidation of powders happens in the electrochemical etching of the surface, stops the release of oxygen at the anode. This dramatically reduces the performance of the process, because the conductivity of semiconductors is considerably less than that of metals. When Dand>1 A/cm2there is an increase in electrolyte temperature up to the boiling temperature, which leads to its rapid evaporation and the detuning of the oxidation process of powder waste.

Reducing the number of technological operations is due to the fact that at the stages of the process: the oxidation of waste transfer gallium in the gallate, sodium electrochemical selection gallium occurs when only a single operation.

A specific example of the method.

In the anode section of the cell load previtellogenesis them gallium, then the cell is filled with an aqueous solution of a strong base (for example, 20% aqueous sodium hydroxide solution). The cathode and anode sections are divided by a diaphragm, in order to prevent powder from the zone of decomposition (anode section) in the cathode section, where the recovery of gallium from the solution in the form of metal. As the cathode is used, the melt of gallium, the anode is made, for example, of Nickel, its design provides maximum contact area with the electrolyte waste. After that, turn the power supply to the electrolyzer. Set the anode current density Dandor =0.6 A/cm2. Other process parameters (density cathode current process temperature) is chosen in such a way as to ensure the maximum degree of extraction of gallium. In the course of the process in the anode section is the decomposition of waste due to their oxidation by atomic oxygen, gallium and arsenic transform into soluble compounds that penetrate through the aperture in the cathode section, with a recovery of gallium to metal, arsenic compounds remain in solution and do not interfere with the recovery of gallium to metal. The process ends when all Poroskov the process of producing unloading gallium metal from the cathode section, weigh it and determine the degree of extraction.

Other examples of boundary conditions are shown in table. The dependence of the degree of extraction of gallium from the anode current density.

The method of extraction of gallium from geliysoderzhaschih powdered waste including waste decomposition in the presence of an oxidant and electrochemical allocation of gallium at the cathode, characterized in that the extraction is carried out in the electrolytic cell with anode and cathode sections decomposition of waste in the anode section in an aqueous solution of a strong base in the presence of as oxidant atomic oxygen evolved at the anode when the anode current density of 0.2 Dand1 A/cm2.



 

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