RU2490375C2 - Electrolysis unit for extraction of indium from indium-containing molten metal in form of condensate from vacuum furnace - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: electrolysis unit includes a heated anode bath, a cathode cell in the form of a perforated cylinder having two diaphragms, a current lead and a collecting bowl for indium extracted from molten metal, which is fixed on it. As the anode bath, it contains a receiving molten bath of condensate from a vacuum furnace, which contains bismuth, tin and indium. The cathode sell is made in the form of a perforated cylinder enclosed in a diaphragm from quartz cloth, equipped with a shell and a cylindrical insert from electroinsulating material, which is arranged in lower part. The shell and the cylindrical insert are enclosed in a diaphragm from quartz cloth with formation of a gap between two 2-5 mm diaphragms in the form of an electrolyte pouring pocket.

EFFECT: invention improves indium extraction.

2 cl, 2 dwg, 1 tbl, 1 ex

Description

The invention relates to non-ferrous metallurgy, in particular to the extraction of indium by electrolysis in a molten salt.

In the process of vacuum refining of tin [1], indium, along with other volatile impurities, evaporates from tin, and the purified tin flows through the tin pipe into a tank and is poured into blocks of finished products. Impurities condense on cold screens and flow down a barometric pipe into a receiving tank, and then they are poured into blocks of a lead-bismuth alloy that contains indium.

In the known device [2], a lead-bismuth alloy is melted and mixed with a salt melt of zinc chloride to extract indium from the molten condensate of vacuum refining into a salt melt. Indium is extracted into a molten salt based on zinc chloride. The molten salt is drained and dissolved in an acidic medium, and indium is cemented from the solution on zinc sheets. The indium sponge is melted into a rough indium alloy.

In the known electrolyzer [3], a rough indium alloy is refined by electrolysis in a melt based on zinc chloride.

A disadvantage of the known devices at high cost due to the multi-stage process.

Known and adopted as a prototype [4] an electrolyzer containing heated cathode and anode baths separated by porous diaphragms saturated with electrolyte, characterized in that the cathode bath is made in the form of a perforated cylinder on which two layers of a quartz fabric diaphragm are fixed, and vertically immersed in alloy of the anode bath, and inside the cathode bath is inserted a bowl mounted on the cathode current lead. The cell is significantly reduced the number of redistributions.

The disadvantage of this prototype of the electrolyzer is that it requires separate processing of separation and melting of condensate blocks from the furnace, electrolysis and casting of the anode alloy, frequent replacement of diaphragms due to evaporation of the electrolyte, which becomes an uneconomical processing of condensate with an indium content of less than 0.05% .

An object of the invention is to eliminate the operation of melting the alloy and increasing the extraction of indium by involving the alloy with any low content of indium.

The essence of the proposed electrolyzer is that as an anode bath it contains a heated receiving bath of molten condensate from a vacuum furnace containing lead, bismuth, tin and indium. The cathode cell is made in the form of a perforated cylinder, covered with a quartz fabric diaphragm, equipped with a shell and placed in the lower part of a cylindrical insert of electrical insulating material. In this case, the shell and the cylindrical insert are covered with a quartz fabric diaphragm with the formation of a gap between two 2-5 mm diaphragms in the form of a pocket for filling the electrolyte.

The technical result is achieved by the fact that the electrolyzer with the anode of the receiving bath at the condensate outlet of the vacuum furnace allows to obtain cathode rough indium without bottling, remelting. Pocket filling electrolyte between the layers of the diaphragm and periodic unloading of the accumulated cathode metal in accordance with the continuous operation of the vacuum furnace and to increase the total extraction of indium.

In the drawings of figure 1 shows a General view of the electrolyzer, and figure 2 - installation of the electrolyzer on a vacuum furnace.

The cell contains an anode bath 1 (condensate receiving bath) and a cathode current lead 2 connected to the negative pole of a DC rectifier. In the lower part, the current supply is equipped with a cathode bowl 3. The current supply 2 with a bowl 3 is immersed in a perforated cylinder 4, fitted with a diaphragm 5 made of KT-11 c8 / 3TO quartz fabric, fixed with a clamp 6 on a perforated cylinder 4. Perforated cylinder 4, covered with fabric 5 , inserted into the casing 7 with a pocket 8. The casing 7 is covered with a diaphragm 9 made of CT quartz fabric with a certain gap of 2-5 mm from the diaphragm 5, and secured with a similar clamp 6.

In the lower part of the diaphragm 9 is formed on a cylindrical insert 10 of an electrically insulating material, for example fluoroplastic. The nodes 4, 5, 6, 7, 8, 9, 10 assemble to form a cathode cell 11, which is immersed in the molten anode metal in the receiving bath 1, on an electrically insulating stand 12.

The receiving anode bath 1 is equipped with a tray 13 for draining the melt, condensing impurities from the vacuum furnace of FIG. 2. A barometric condensate pipe 14 of a drain of volatile impurities containing indium 18, a refined tin barometric pipe 19 and a tin discharge tank 20 is immersed in the receiving anode bath 1.

The cell operates as follows.

Liquid condensate containing lead, bismuth, tin and 0.03-0.1% indium continuously flows into the receiving bath 1, which serves as the anode (Fig. 1). In the melt of the receiving anode bath 1, the cathode cell 11 is immersed on the stand 12. In the pocket 8 of the shell 7, an electrolyte containing zinc, potassium, sodium chlorides is poured into the gap (2-5 mm) between the diaphragms 5, 9 for tissue impregnation. The electrolyte wets the fabric of the diaphragms 5, 9, stretched over the perforated cylinder 4 and the cage 7. The CT tissue becomes capable of transporting metal ions of the electrolyte. The fabric is not wetted by metal and is not permeable to metal (permeability pressure 10 kg / cm ² fabric). Through the electrodes include direct current voltage of 1-30 V with a current density of 0.02-0.2 A \ cm ² . Indium cations diffuse through the electrolyte in the capillaries of two layers of tissue and are discharged at the cathode-bowl 3, and accumulate in the cylinder 4, covered with a diaphragm 5. More positive bismuth, as a rule, in the presence of indium, lead is not ionized.

As the cathode cell 11 is filled with indium in an alloy with lead, the cup 3 on the cathode current lead 2 is periodically removed and indium is poured. Periodically once a day, electrolyte is added to pocket 8. The operation of draining the cathode indium alloy is repeated until the filling of the bowl 3. The anode lead-bismuth alloy (with indium removed) is continuously discharged from the receiving bath-anode 1 through the tray 13 into the molds as a finished product.

The technical result of the proposed electrolyzer is that the cost of redistribution of melting is reduced and the extraction of indium from the alloy is increased, due to the fact that indium is extracted from any of the contents of the composition without preparatory operations.

Example: A 1 kg sample of a condensate of an alloy containing 0.03% indium; 8% tin; 87% lead; 2% bismuth; 3% of antimony is poured into the model of the anode bath and maintain a temperature of 400 degrees. A cathode cell is lowered into the melt of the anode bath. 25 g of electrolyte, a pre-melted mixture of salts of 49% zinc chloride, 44% potassium chloride, 7% sodium chloride, is poured into the cathode cell in the gap between the diaphragms of the KT-11 s8 / 3TO brand quartz fabric. A direct current of 1 A voltage of 5 V is turned on and electrolysis is carried out for 3 hours. Every hour, 1 kg of the initial alloy is added in bullion. At the same time, an excess of spent anode alloy flows from the bath model. In just 3 hours, 3 kg of condensate alloy is loaded. The cathode cell is lifted and the cathode metal is drained.

The test results of the extraction of indium from the condensate alloy with different indium contents are given in the table.

Table The results of the experiments of the example options Experience number one 2 The content of In% in the anode 0,03 0.13 Weight of initial alloy condensate, kg 3 3 Current strength, A one one Duration, h 3 3 Weight of cathode alloy, g 6 8.2 The content of In% in the cathode 14,4 46.6 The final content of In% in the anode 0.002 0.003 Removing% In from the Anode 93.3 97.7

An example shows that the proposed electrolyzer allows to increase the extraction of indium from the condensate alloy with both poor and rich indium content without hydrometallurgical processing operations.

Thus, the proposed electrolyzer allows to increase the extraction and reduce the total cost of associated extraction of indium.

List of analogues

[1] Pat. Russia - No. 1489195 - Mcl. С22в 9/04 - Vacuum apparatus for the refining of tin.

[2] Pat. Russia - No. 1401903 - С22В 58/00 - Apparatus for extracting indium from molten metals.

[3] Pat. Russia - 1482248 - MKI S25S 7/00 - Electrolyzer for refining low-melting metals.

[4] Application of Russia - No. 20111132432 - C25C 7/04, publ. - December 10, 2011.

Claims (2)

1. An electrolyzer for extracting indium from an indium-containing melt, including a heated anode bath, a cathode cell in the form of a perforated cylinder having two diaphragms made of quartz fabric, a current conductor and a bowl fixed thereon for collecting indium extracted from the melt, characterized in that it is an anode bath it contains a receiving bath of condensate melt from a vacuum furnace containing lead, bismuth, tin and indium, the cathode cell is made in the form of a perforated cylinder covered with a quartz fabric diaphragm, equipped with The shell and the cylindrical insert located in the lower part are covered with a quartz fabric diaphragm to form a gap between two 2-5 mm diaphragms in the form of a pocket for filling the electrolyte. 2. The electrolyzer according to claim 1, characterized in that the cathode cell is placed in the anode bath on an insulating stand.

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