RU2595302C2 - Electrolytic cell for extraction of indium from melt of condensate at outlet of vacuum furnace - Google Patents

Abstract

FIELD: electrochemistry.

SUBSTANCE: invention relates to extraction of indium by electrolysis. Disclosed is an electrolytic cell for extraction of indium from melt discharge of condensate of refining crude tin from vacuum furnace. Electrolytic cell comprises heated condensate tank of a vacuum furnace, used as anode bath, immersed therein a cathode cell with perforated walls, lined with a diaphragm made of quartz cloth, barometric pipe, cathode current lead and a cup fixed thereon and placed inside cathode cell. Cell additionally comprises cathode plates. Cathodic cell walls are composed of two perforated strips coiled into a spiral to form a gap between them for electrolyte and immersion therein of cathode plates. Wall of cell on one side is fixed on inner side of condensate tank, and on other on barometric pipe. Cathode plates are made of zinc alloy.

EFFECT: higher extraction of indium from condensate.

1 cl, 3 dwg

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 down 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 zinc chloride molten salt to extract (extract) indium from the molten condensate of vacuum refining into a molten salt. 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 is the high cost due to the multi-stage process.

Known [4] is an electrolyzer containing heated cathode and anode baths separated by porous diaphragms impregnated with an electrolyte, characterized in that the cathode bath is made in the form of a perforated cylinder on which two layers of a diaphragm are made of quartz fabric, and vertically immersed in the alloy of the anode bath, and inside the cathode bath is inserted a bowl mounted on the cathode current lead. The electrolyzer significantly reduces the number of redistributions, but its disadvantage is that it requires separate redistribution of the separation and melting of condensate blocks from the furnace, electrolysis and casting of the anode alloy, which creates conditions for uneconomical processing of condensate with an indium content of less than 0.05%.

Known and adopted as a prototype [5] an electrolyzer containing a heated bath of a vacuum furnace serving as an anode, a cathode cell in the form of a perforated cylinder, covered with two layers of a fabric diaphragm, separated from the anode bath by fabric diaphragms, with a cup inside the cathode cell mounted on the cathode current lead .

The disadvantage of this prototype electrolyzer is that it is unstable at high productivity of the resulting condensate with a high indium content. In this case, there is a high velocity of the condensate (anode alloy) along the diaphragm, and the diffusion rate is insufficient for ionization of indium and passage through the diaphragm from the entire volume of the alloy. This reduces the recovery of indium.

The aim of the invention is to increase the area of the diaphragm relative to the volume of the anode alloy in the bath to ensure a sufficient degree of extraction of indium from the alloy at high productivity of the resulting condensate or a high concentration of indium in the condensate.

The essence of the proposed electrolyzer for the extraction of indium from the outlet of the molten condensate of refining rough tin from a vacuum furnace is that the electrolyzer containing a condensate tank of a vacuum furnace serving as an anode bath, a cathode cell immersed in it with perforated walls fitted with a fabric diaphragm, a barometric pipe, the cathode current lead mounted on it and placed inside the cathode cell bowl, characterized in that it further comprises cathode plates immersed in the cell. The walls of the cathode cell are made in the form of two perforated tapes, rolled into a spiral with the formation of a gap between them for the electrolyte. Perforated tapes are covered with a quartz fabric diaphragm, one side fixed on the inside of the condensate tank, and the other on a barometric pipe. An electrolyte is poured into the gap between the tapes, zinc alloy plates and a cathode current lead with a bowl are immersed.

The technical result is achieved by increasing the area of the diaphragm of separation of the anode and cathode, increasing the length of stay of the alloy at the diaphragms before its continuous discharge.

The technical result is that it provides an increase in the degree of extraction of indium from the alloy with high productivity of the resulting condensate or a high concentration of indium in the condensate.

In the drawings of FIG. 1 shows a general view of the electrolyzer, and in FIG. 2 is a top view of the cell, FIG. 3 is a diagram of a vacuum furnace.

The cell contains a condensate bath 1 serving as an anode bath, in the center with a barometric tube 2 of a vacuum furnace. A cathode cell 3 of two perforated stainless steel mesh tapes 4 rolled into a spiral is immersed in the anode bath. One side of the perforated wall 4 in the form of a stainless steel mesh tape is fixed with a lock 5 on the inside of the anode bath 1. The other side of the perforated wall 4 of the mesh is fixed with a lock 6 on the barometric tube 2. The diaphragms are tightly tightened and fixed to the perforated walls (mesh) 4 made of quartz fabric, for example, grade KT-11 s8 / 3TO, forming the inner diaphragm 7 and the outer diaphragm 8. Between the diaphragms 7, 8, electrolyte is poured, the plates 9 and the cathode current lead with a bowl 10 are connected, connected to the negative floor Su dc rectifier. Above the anode bath is equipped with a drain tray 11 drain melt. The diaphragms 7, 8 are fixed on the mesh tape 4 with clips 12 and are sealed with sealant ΒΓΟ1. The bottom of the barometric pipe 2 is equipped with a cutout 13 for directional discharge of the condensate alloy along the diaphragm 7.

Bath 1 as a node of a vacuum furnace (Fig. 3) serves as the anode into which the barometric pipe 2 of the alloy liquid condensate drain is immersed. The vacuum furnace, in addition to the condensate bath 1 and the barometric condensate pipe 2, contains a vacuum chamber 14, a source tin boiler 15, evaporation trays 16, condensation screens 17, a refined tin barometric pipe 18 and a tin discharge tank 19.

The cell operates as follows.

In the vacuum furnace (Fig. 3), crude tin from the boiler 15 is suctioned by vacuum into the vacuum chamber 14 and drained by means of a barometric tube 18 into the receiving tank 19. The admixtures of lead and indium are evaporated on the evaporation plates 16 and condensed on the screens 17 and drained through the barometric pipe 2 into the intake tank 1.

A cathode cell 3 (Fig. 1, 2) of two perforated walls 4 of mesh tapes, onto which diaphragms 7, 8 of quartz fabric are tightly fastened and fastened, is immersed into the condensate bath 1, which serves as the anode.

In the gap between the diaphragms 7, 8 on the walls, the cathode plates 9 and the cathode current lead with a bowl 10 are connected, connected to the negative pole of the DC rectifier. In the gap between the diaphragms 7, 8 for tissue impregnation, the electrolyte is poured in the form of a molten salt of 74-70% zinc chloride, 16-18% potassium chloride, 10-12% sodium chloride. Quartz fabric is not wetted by metal and impermeable to metal, but permeable to transfer ions through a fabric moistened with electrolyte.

Into the condensate bath 1 of the furnace, which serves as the anode (Fig. 1, 2), liquid condensate, an alloy containing lead, bismuth, tin and 0.03-0.2% indium, continuously flows from the barometric pipe 2 through the gap 13 at the bottom. The alloy flows in a spiral along the diaphragms to the drain tray 11 (shown by arrow).

A constant current voltage of 1-20 V with a current density of 0.02-0.2 A / cm ^{2 is} connected to the bath 1 and current lead 10. Indium cations diffuse through the electrolyte in the capillaries of the tissue and discharge on the cathode sheets 9, drain to the bottom of the gap between the diaphragms 7, 8 and fill the bowl 10. The more positive bismuth, lead, and tin in the presence of indium do not ionize and flow down the tray 11 from the bath. Periodically once a day, the cup on the cathode current lead 10 is removed and the indium alloy is poured. The length of the diaphragms increases by 6 times in comparison with the prototype with the same diameter and height of the tank.

The technical result of the proposed electrolyzer is that the electrolyzer provides an increase in the extraction of indium from the condensate of the vacuum furnace with a high condensate formation rate and a high indium content due to the increased 6-fold diaphragm area with the same bath volume.

Information sources

[1] Pat. Russia №1489195. Tin refining vacuum apparatus. Ml C22B 9/04.

[2] Pat. Russia №1401903. An apparatus for extracting indium from molten metals. Ml C22B 58/00.

[3] Pat. Russia №1482248. Electrolyzer for refining low-melting metals. Ml C25C 7/00.

[4] Pat of Russia No. 2463388. Electrolyzer for extracting indium from melts. Publ. 12/10/2011. Ml C25C 7/04.

[5] Pat. Russia №2490375. An electrolyzer for extracting indium from an indium-containing melt in the form of condensate from a vacuum furnace. Ml C25B 9/04.

Claims (2)

1. An electrolyzer for extracting indium from the outlet of a melt of condensate of refining rough tin from a vacuum furnace, containing a heated tank of condensate of a vacuum furnace, used as an anode bath, a cathode cell immersed in it with perforated walls covered with a quartz fabric diaphragm, a barometric tube, a cathode current supply and a cup fixed on it and placed inside the cathode cell, characterized in that it further comprises cathode plates, and the walls of the cathode cell are made in the form of two ne forirovannyh ribbons rolled into a spiral to form a gap between them for electrolyte, and immersion therein of cathode plates, wherein the wall on one side of the cell is fixed on the inner side of the condensate tank, and the other - to the barometric tunnel. 2. The electrolyzer according to claim 1, characterized in that the cathode plates are made of zinc alloy.

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