RU2741025C2 - Gallium purification cell - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to an electrolysis unit for gallium refining. Electrolysis cell comprises anode bath for liquid gallium and electrolyte with current lead, cathode cell with cathode bath from liquid cathode gallium and electrolyte, made with current lead and with perforated bottom, vessel with porous bottom for settling and filtration of electrolyte, siphon of electrolyte return to cathode bath and pump for electrolyte with suction nozzle and with delivery branch pipe, float, connection pipe for sludge collection from anode surface, connected by flexible hose with suction pump union and arranged on float with possibility of its location on boundary of electrolyte-gallium phases of anode bath for suction of sludge from anode surface and maintaining level of anode bath, tray for excess electrolyte drainage from cathode bath surface located on opposite side from electrolyte return siphon into cathode cell, and filter with porous bottom for filtration of sludges and drain into electrolyte tank, to which is brought pump tube assembly, and in its middle part there is pipeline with siphon for connection with level of cleaned electrolyte on cathode bath.

EFFECT: higher degree of purification due to removal of slurries during their formation.

1 cl, 2 dwg, 1 tbl

Description

The invention relates to the field of refining non-ferrous metals, and in particular, to electrical methods for refining metallic gallium.

The known electrolyzer contains a bath with electrolyte and liquid gallium separated by a partition for the cathode and anode space [1].

The prototype is an electrolyzer containing a bath with a liquid gallium anode, a cathode cell with a perforated bottom and a current lead located above it [2].

The disadvantage of this electrolyzer is insufficient mixing of the electrolyte and saturation of the electrolyte with sludge. The changing interelectrode distance from the dissolution of the anode leads to overvoltage at the anode, affecting the dissolution of the slimes of electropositive impurities. Agitators for mixing only contribute to the distribution of the slimes throughout the volume. This leads to a decrease in the quality of the product.

The technical problem is to remove the sludge generated at the anode not from the volume of the changing gap, but directly from the anode surface at the time of formation and to prevent sludge on the cathode surface.

The essence of the electrolyzer is that it is equipped with a float, a fitting for collecting sludge from the surface of the anode, connected by a flexible hose to the suction fitting of the pump and placed on the float with the possibility of its location at the interface between the electrolyte and gallium of the anode bath for sucking the sludge from the surface of the anode and maintaining the level of the anode bath.

This prevents the accumulation of sludge, which after accumulation begins to dissolve and then contaminate the cathode.

The electrolyzer is equipped with a tray for draining excess electrolyte from the surface of the cathode bath, located on the opposite side of the siphon for returning the electrolyte to the cathode cell, and a filter with a porous bottom for filtering sludge and drain into the electrolyte tank, to which the pump discharge pipe is connected, and in its middle part, there is a pipeline with a siphon for communication with the level of the purified electrolyte on the cathode bath.

It also contributes to allow the selective collection of sludge from the anode surface and to create a movement of the electrolyte layer, and also contributes to the renewal of the dissolution surface of the anode and the renewal of the electrolyte on the gallium deposition surface on the cathode.

The design of the electrolyzer is illustrated in Fig. 1 and a cross section of Fig. 2. The electrolyzer consists of a bath 1 for the electrolyte and a liquid gallium anode 2. A current lead 3 with a nickel plate is immersed in it. Cell 4 (one or more) is installed parallel to the surface of the anode 2. Cathode cell 4 in the form of a rectangular box made of plastic with a perforated bottom 5, along which a diaphragm 6 made of nylon fabric is pulled and fixed from above in any way, for example, a shell. A current lead 8 in the form of a nickel plate is installed on the surface of the diaphragm 6 in a layer of liquid cathode gallium 7. Current lead 8 is connected to the negative pole of the direct current source. In one end of the bath behind the partition 10 with a window 11, a submersible pump 12 is installed for pumping out the electrolyte from the surface of the anode gallium. The suction nozzle of the pump 12 is connected by a flexible hose to the nozzle 13 on the float to keep afloat on the metal of the anode. This allows the nozzle 13 to be at the electrolyte-gallium phase separation when its level changes in the intervals between charges (the dashed line shows the minimum and maximum level of the anode metal. The pump discharge pipe is connected to the filter 14 with a porous bottom for filtering sludge and drain into the electrolyte tank 15. In the middle part, the container 14 is equipped with a pipeline 16 with a sip 17 for communication with the level of the purified electrolyte on the cathode bath (Fig. 2), mounted on the brackets 18.On the opposite side of the bath from the siphon 17, the flow of purified electrolyte, the cathode bath is equipped with a drain pan 19 depleted in gallium electrolyte in the anode bath Bath 1 is equipped with a siphon pocket 20 for pouring liquid gallium on the bottom of the bath and immersion of the current lead 3. The bottom of the bath 1 is made with a cooling cavity divided by partitions 21. The cooling cavity is equipped with fittings 22 for supplying and removing water for temperature control.

The electrolyzer works as follows. Bath 1 is filled with electrolyte from a 10-20% solution of sodium hydroxide of high purity. Liquid gallium is poured into the bottom of the bath 1 through the siphon pocket 20 as anode 2.

A direct current with a voltage of 2-4 V and a current of 20-100 a bursts to the current leads 8, 3, gallium from the anode 2 dissolves into the electrolyte and at a concentration of 10-50 g / l Ga diffuses through the diaphragm 6 (nylon fabric), is deposited on the current supply plate 8, and as the accumulation of gallium is deposited on the entire surface of the liquid cathode 7. After the accumulation of liquid gallium 7 on the cathode in the cell 4 with a layer of 3-4 cm, it is periodically drained by any method (scooping or vacuum suction). Liquid gallium is added periodically through the siphon pocket 20. At start-up, hot water (40-60 ° C) is supplied to the cooling cavity through the nozzle 22, and during continuous operation, cold water is supplied to cool liquid gallium at the anode 2. During electrolysis, impurities in the form of hydrates accumulate in the electrolyte layer on the anode surface. The pump 12 sucks in the electrolyte with sludge through the nozzle 13 floating on the surface of the anode metal 2. The electrolyte is pumped into the pressure filter 14 with a porous bottom to filter the sludge of solid impurities. After separating the sludge on the filter 14 through channel 16, it is fed to the siphon 17 of the cathode cell 4 of the cathode gallium 7.

Example: 3.5 l of 100 g / l NaOH solution is poured into the anode bath. The bathtub is heated with hot water up to 50 degrees. Through pocket 20, 3 kg of liquid gallium is poured onto the anode. Current leads 3 and 8 are supplied with a constant current with an adjustable current strength of 20A and a voltage of 5V. A peristalic pump is turned on for uniform distribution of the electrolyte in the anode and cathode volumes. Regularly after 2 hours, an electrolyte sample is taken for gallium content. 12 hours after the accumulation of gallium in the electrolyte up to 20 g / L, the current increases to 60A. After another 48 hours, the gallium content in the electrolyte is 48 g / l. For the continuity of the process, additional loading of the anode is necessary, but to take readings, cathode gallium is unloaded for weighing and analysis, and sludge is collected for analysis. The results are shown in the table.

The technical result of the invention is expressed in stirring the electrolyte at the surface of the anode, cleaning the electrolyte from sludge and, thereby, increasing the cleaning factor. The proposed electrolyzer according to the invention provides for the purification of gallium from impurities to a gallium content of 99.8% (according to the prototype) to 99.99%.

Literature:

1. Patent of Russia No. 2127328 on application No. 97111637 dated 1997.07.15. Method for producing gallium, C22B 58/00, published 03/10/1999.

2. Kolenkova M.A., Kerin O.E. Metallurgy of scattered and light rare metals, 1977, 143 p.

Claims (1)

An electrolyzer for refining gallium, containing an anode bath for liquid gallium and electrolyte with a current lead, a cathode cell with a cathode bath of liquid cathode gallium and electrolyte, made with a current lead and with a perforated bottom, a vessel with a porous bottom for settling and filtering the electrolyte, a siphon for returning the electrolyte to a cathode bath and an electrolyte pump with a suction nozzle and a discharge nozzle, characterized in that it is equipped with a float, a nozzle for collecting sludge from the anode surface, connected by a flexible hose to the pump suction nozzle and placed on the float with the possibility of its location at the electrolyte phase boundary - gallium of the anode bath for suction of sludge from the surface of the anode and maintaining the level of the anode bath, a tray for draining excess electrolyte from the surface of the cathode bath, located on the opposite side from the siphon of electrolyte return to the cathode cell, and a filter with a porous bottom for filtering sludge and drain into the container for elect it, to which the discharge pipe of the pump is connected, and in its middle part there is a pipeline with a siphon for communication with the level of the purified electrolyte on the cathode bath.

Images