阅读说明：本技术 一种粗镓的电解精炼装置及电解精炼方法 (Crude gallium electrolytic refining device and method ) 是由 许志鹏 邹铭金 郭学益 田庆华 李栋 于 2021-07-08 设计创作，主要内容包括：本发明公开了一种粗镓的电解精炼装置,包括电解槽,所述电解槽内设有用于容置粗镓阳极的阳极区和用于容置高纯镓阴极的阴极区,所述阳极区和阴极区相互独立,所述阴极区为螺旋阶梯式流道结构,所述螺旋阶梯式流道结构的流道两侧及底部封闭,顶部设有与电解液接触的开口。本发明还提供一种利用上述的电解精炼装置电解粗镓的电解精炼方法。本发明的粗镓的电解精炼装置,该装置的阴极区为螺旋阶梯式流道结构,极大地扩展阴极区面积,实现低电流密度下大工作电流生产,在保证了产品的纯度的同时能够增产提效。(The invention discloses an electrolytic refining device for crude gallium, which comprises an electrolytic bath, wherein an anode region for accommodating a crude gallium anode and a cathode region for accommodating a high-purity gallium cathode are arranged in the electrolytic bath, the anode region and the cathode region are mutually independent, the cathode region is of a spiral stepped flow channel structure, two sides and the bottom of a flow channel of the spiral stepped flow channel structure are closed, and the top of the flow channel is provided with an opening which is in contact with electrolyte. The invention also provides an electrolytic refining method for electrolyzing the crude gallium by using the electrolytic refining device. According to the electrolytic refining device for the crude gallium, the cathode area of the device is of a spiral stepped flow channel structure, the area of the cathode area is greatly expanded, the production of large working current under low current density is realized, and the yield and the efficiency can be increased while the purity of the product is ensured.)

1. The electrolytic refining device for the crude gallium comprises an electrolytic cell (1) and is characterized in that an anode region (2) used for containing a crude gallium anode and a cathode region (3) used for containing a high-purity gallium cathode are arranged in the electrolytic cell (1), the anode region (2) and the cathode region (3) are mutually independent, the cathode region (3) is a spiral stepped flow channel structure (4), two sides and the bottom of a flow channel of the spiral stepped flow channel structure (4) are sealed, and an opening in contact with electrolyte is formed in the top of the flow channel.

2. Electrorefining apparatus according to claim 1, characterized in that the spiral stepped flow channel structure (4) is arranged along the inner side wall of the electrolytic cell (1), and the flow channel width of the spiral stepped flow channel structure (4) becomes wider from top to bottom, and the spiral stepped flow channel structure (4) is provided with a discharge valve (5) near the bottom of the electrolytic cell (1).

3. An electrorefining apparatus as claimed in claim 1, characterized in that an annular partition (6) is provided in the centre of the bottom of said electrolytic cell (1), said anode region (2) being located inside said annular partition (6); the electrolytic refining device further comprises a stirring device, the stirring device comprises a stirring paddle (7) with double layers of paddles, a bottom paddle (71) is located in the anode region (2), and an upper paddle (72) is located above the anode region (2).

4. An electrorefining apparatus as claimed in any one of claims 1 to 3 wherein the electrorefining apparatus further comprises a replacement fluid deslagging tube (8), one end of the replacement fluid deslagging tube (8) being located within the anode region (2).

5. An electrorefining method for electrolyzing crude gallium by using the electrorefining apparatus as claimed in any one of claims 1 to 4, comprising the steps of:

s1: respectively injecting liquid crude gallium and high-purity gallium into an anode region (2) and a cathode region (3), arranging an electrolysis lead, adding electrolyte into an electrolytic cell (1), and then electrifying for electrolysis;

s2: supplementing crude gallium to the anode region (2) in the electrolysis process, and collecting electrolysis products from the cathode region (3);

s3: and washing the electrolysis product to obtain the high-purity gallium.

6. The electrorefining method of claim 5, wherein the electrolyte comprises 80-100g/L NaOH and 8-12g/L NaGaO₂The liquid level after the electrolyte is added is determined according to the condition that the electrolyte covers the cathode region (3) under the stirring condition.

7. An electrorefining process as claimed in claim 5, characterized in that the purity of the crude gallium of the anode region (2) is 3N, the purity of the high purity gallium of the cathode region (3) is 6N, and the electrolytic lead is a platinum wire with a purity of 5N.

8. The electrorefining method as claimed in any one of claims 5 to 7, wherein during the electrification and electrolysis, the stirring is started to heat the water bath, the stirring speed is controlled to be 200rpm and 300rpm, the stirring direction is consistent with the spiral direction of the spiral stepped flow channel structure (4), and the heating temperature of the water bath is controlled to be 36-40 ℃.

9. The electrolytic refining method as claimed in any one of claims 5 to 7, wherein the current density is controlled to 200-300A/m during the electrification electrolysis²The cell voltage is 2-3V.

10. The electrolytic refining method according to any one of claims 5 to 7, wherein the electrolytic product is washed by two-stage stirring washing with an inorganic strong acid and ultrapure water, the inorganic strong acid comprises hydrochloric acid or sulfuric acid, the mass fraction of the hydrochloric acid is 10 to 15%, the mass fraction of the sulfuric acid is 15 to 20%, the washing temperature is controlled to be 50 to 60 ℃, and the magnetic stirring speed is controlled to be 200-400rpm during stirring.

Technical Field

The invention belongs to the field of metal purification, and particularly relates to a device and a method for electrolyzing crude gallium.

Background

Gallium is a rare and dispersive metal with low melting point and high boiling point, and a compound formed by the gallium and elements such as nitrogen, oxygen, arsenic and the like has excellent semiconductor characteristics, and is widely applied to the fields of solar batteries, LEDs, wireless communication and the like. With the development of new energy and 5G communication technology in recent years, the demand for gallium is increasing, and the demand for gallium purity is also increasing.

At present, the method for preparing high-purity gallium mainly comprises an electrolytic refining method, a zone melting method, a crystallization method and the like. The zone melting method has the advantages of small production scale, high energy consumption, low yield, high crystallization cost and high operation difficulty, and the electrolytic refining has low requirements on equipment and is simple to operate and easy to realize industrial production.

The electrolytic refining of gallium is mainly carried out under alkaline conditions, with NaOH and NaGaO₂The solution is used as electrolyte, crude gallium is used as anode, platinum sheet or platinum rod is used as cathode, liquid crude gallium at anode is dissolved in electrolytic process, and GaO in electrolyte₂ ^-The ions reach the cathode through migration and are discharged and separated out, and the separation and purification are carried out by utilizing the difference of the separation potentials of gallium and various impurity elements.

The research and analysis of the inventor find that the main problems of the gallium electrolytic refining are as follows: the cathodic current efficiency is low, and the hydrogen evolution side reaction is serious. The cathode material is often platinum sheet or platinum plate, and platinum is used for H₂Has higher catalytic activity and the evolution potential of hydrogen on the platinum surface is higher than that of GaO₂ ^-The Ga content is high, and stainless steel materials also have lower hydrogen evolution overpotential, so that the cathode is always accompanied by stronger hydrogen evolution reaction in the electrolysis process, the electrolysis balance is damaged, and even the Ga precipitation at the cathode is inhibited, so that the gallium electrolysis efficiency is lower. Secondly, the production period, the yield and the product purity are difficult to be balanced. The electrolysis period is short and the yield is high under the heavy current density, but the impurities such as Cu, Pb and the like are easily precipitated to cause the low purity of the product. If low current density electrolysis is adopted for improving the purity of the gallium product, the electrolysis period is long and the yield is low; and the anode is easy to passivate. When NaOH and GaO are in solution₂ ^-Too high a concentration may cause passivation of the anode. In view of the above problems, it is necessary to develop an apparatus and a method for electrorefining of crude gallium.

Disclosure of Invention

The invention aims to overcome the defects and shortcomings in the background technology and provide an electrolytic refining device and an electrolytic refining method for crude gallium, which can ensure the purity of products and increase the yield and improve the efficiency. In order to solve the technical problems, the technical scheme provided by the invention is as follows:

the electrolytic refining device for the crude gallium comprises an electrolytic cell, wherein an anode area used for accommodating a crude gallium anode and a cathode area used for accommodating a high-purity gallium cathode are arranged in the electrolytic cell, the anode area and the cathode area are mutually independent, the cathode area is of a spiral stepped flow channel structure, two sides and the bottom of a flow channel of the spiral stepped flow channel structure are sealed, and an opening in contact with electrolyte is formed in the top of the flow channel. Above-mentioned cascaded runner structure of spiral is like spiral stair form, vertical direction setting, and the upper portion opening of runner is used for contacting with electrolyte.

Among the above-mentioned electrolytic refining device, preferred, the cascaded runner structure of spiral is followed the electrolysis trough inside wall sets up, just the runner width of the cascaded runner structure of spiral is from last to becoming widen gradually down, the cascaded runner structure of spiral is close to electrolysis trough bottom department is equipped with the baiting valve. The outer edge of the spiral stepped flow channel is parallel and level to the inner side wall of the electrolytic cell in the vertical direction, the inner edge of the flow channel is closer to the center of the electrolytic cell from top to bottom, and the design of gradually widening from top to bottom is adopted. The upper layer of the electrolytic cell with the structural design has larger operable space, can be assisted by a stirring device to facilitate the effective ions in the electrolyte to better transfer mass to the cathode, and can ensure the area of the cathode area. The runner trend of the spiral stepped runner structure can be clockwise spiral downwards, refined high-purity gallium is laid in the runner to serve as a cathode, the refined high-purity gallium is in contact with electrolyte through a top opening (preferably a top full opening), and the refined high-purity gallium is connected with the cathode of an electrolytic power supply through a platinum wire lead. Gallium accumulated at the cathode may be tapped off through a bleed valve.

In the above electrolytic refining apparatus, preferably, an annular partition is provided at the center of the bottom of the electrolytic bath, and the anode region is located at the annular partitionThe interior of the panel; the electrolytic refining device further comprises a stirring device, the stirring device comprises a stirring paddle with double layers of blades, the bottom layer blade is located in the anode area, and the upper layer blade is located above the anode area. The height of the annular partition is preferably 1/4-1/3 of the height of the electrolytic cell. The stirring device can be made of polytetrafluoroethylene. The stirring paddle with double layers of blades can be used for stirring the electrolyte and the anode region at the same time, the stirring structure is simpler, and the GaO is strengthened in the stirring process₂ ^-The mass transfer effect in the solution avoids concentration polarization, and on the other hand, the continuous stirring of the anode crude gallium can strengthen the dissolution of the anode and also avoid the passivation phenomenon of the anode.

In the above electrolytic refining device, preferably, the electrolytic refining device further includes a liquid supplementing and slag removing pipe, and one end of the liquid supplementing and slag removing pipe is located in the anode region. The liquid supplementing and deslagging pipe supplements crude gallium to the anode region and absorbs possible scum on the surface of the anode region, thereby being convenient for realizing continuous production.

The electrolytic cell can adopt a circular groove, the material can adopt a polypropylene material, a concentric annular partition plate is arranged at the center of the bottom of the circular groove, the spiral stepped flow passage structure is arranged around the inner side wall of the circular groove, and the anode region is positioned inside the spiral structure of the spiral stepped flow passage structure. During electrolysis, a platinum wire is used as a lead, and the part of the platinum wire lead passing through the electrolyte is wrapped by silicon rubber.

As a general technical concept, the present invention also provides an electrorefining method for electrolyzing crude gallium using the above electrorefining apparatus, comprising the steps of:

s1: respectively injecting liquid crude gallium and high-purity gallium into an anode region and a cathode region, arranging an electrolysis lead (the exposed part of the lead is immersed in the anode region and the cathode region), adding electrolyte into an electrolytic cell, and then electrifying for electrolysis;

s2: supplementing coarse gallium to the anode region through the liquid supplementing deslagging pipe in the electrolysis process, absorbing possible scum on the surface of the anode region through the liquid supplementing deslagging pipe, and collecting electrolysis products from the cathode region through a bottom discharge valve;

s3: and washing the electrolysis product to obtain the high-purity gallium.

In the above electrolytic refining method, preferably, the electrolyte solution comprises 80-100g/L NaOH (more preferably 90g/L) and 8-12g/L NaGaO₂(more preferably 10g/L), the liquid level after the electrolyte is added is such that the electrolyte covers the cathode region under stirring. The anode passivation is easily caused by the over-high concentration of NaOH, the current efficiency is not high when the concentration of NaOH is over-low, and the adding concentration of NaGaO in the initial electrolyte is 8-12g/L₂The electrolysis reaction can be rapidly generated.

In the above electrolytic refining method, it is preferable that the purity of the crude gallium in the anode region is 3N, the purity of the high purity gallium in the cathode region is 6N, and the electrolytic lead is a platinum wire having a purity of 5N. In the invention, high-purity gallium is used as an actual cathode, and a high-purity platinum wire is used as a lead wire. Compared with the traditional platinum sheet, stainless steel and other materials, the cathode made of high-purity gallium has large hydrogen evolution overpotential and small gallium evolution overpotential, so that the current efficiency of gallium can be effectively improved while the hydrogen evolution side reaction can be inhibited.

In the above electrolytic refining method, preferably, during the electrification electrolysis, the stirring is started to heat the steel plate by a water bath, the stirring speed is controlled to be 200-300rpm, the stirring direction is consistent with the spiral direction of the spiral stepped flow channel structure, and the heating temperature of the water bath is controlled to be 36-40 ℃ (more preferably 38 ℃). The mass transfer is enhanced by stirring the electrolyte, so that more GaO is generated₂ ^-Ions migrate to the surface of the cathode gallium to be discharged and separated out, the electrochemical deposition of effective ions in the cathode area is further increased through the spiral structure of the cathode area, gallium separated out on the surface of the cathode is polymerized under the pushing of stirring consistent with the spiral direction and moves to the bottom of the groove along the flow channel, and the stirring speed can ensure the smooth proceeding of the process. The control of the heating temperature of the water bath is based on the following considerations: the melting point of gallium is 29.78 ℃, the electrochemical reaction is facilitated by keeping gallium in a liquid state, NaOH is easily separated out when the temperature is too high, and the overpotential of hydrogen is reduced by increasing the temperature, so that the gallium is disadvantageously separated out.

In the above electrolytic refining method, it is preferable that the current density is controlled to 200-300A/m during the electrolysis²The cell voltage is2-3V. When the current density is higher, impurities are precipitated to reduce the product purity, and the production efficiency is low when the current density is lower. The invention adopts the electrolysis device with the spiral stepped flow passage structure to greatly increase the area of the cathode, and still has larger working current under lower current density, so that the yield is greatly improved, and the efficiency is also increased.

In the above electrolytic refining method, preferably, when washing the electrolysis product, two-stage stirring washing is performed by using inorganic strong acid and ultrapure water, the inorganic strong acid comprises hydrochloric acid or sulfuric acid, the mass fraction of the hydrochloric acid is 10-15%, the mass fraction of the sulfuric acid is 15-20%, the washing temperature is controlled to be 50-60 ℃, and the magnetic stirring speed is controlled to be 200-400rpm during stirring. More preferably, hydrochloric acid is used, and at room temperature, gallium is slightly soluble in hydrochloric acid, while impurities of gallium are rapidly soluble in the acid. The hydrochloric acid can be used for removing impurities with a negative potential compared with gallium, such as Zn, Al, Fe, Ca, Mg and the like, and the purity of the gallium product can be further improved by washing with ultrapure water to remove the acid. The washing effect can be further improved by magnetic stirring at 200-400rpm under the water bath condition of 50-60 ℃. The electrolytic product of the invention adopts inorganic strong acid-ultrapure water two-stage washing to further improve the purity, and the purity can reach 7N at most.

The electrolytic refining device and the electrolytic refining method adopted by the invention are convenient for continuous production, and the product obtained under the parameters of the invention has higher purity.

Compared with the prior art, the invention has the advantages that:

1. according to the electrolytic refining device for the crude gallium, the cathode area of the device is of a spiral stepped flow channel structure, the area of the cathode area is greatly expanded, the production of large working current under low current density is realized, and the yield and the efficiency can be increased while the purity of the product is ensured. In addition, the gallium precipitated on the cathode is rapidly polymerized under large working current due to the electrode heat release effect, and the electrolysis efficiency can be further improved. In addition, the spiral stepped flow channel structure is convenient for gallium precipitated at the cathode to flow downwards, and electrolytic products are easy to collect.

2. The device and the method for the electrolytic refining of the crude gallium adopt the high-purity gallium as the cathode, can greatly reduce the cost compared with the traditional platinum cathode, and can inhibit the hydrogen evolution reaction in the electrolytic process to greatly improve the current efficiency due to the larger hydrogen evolution overpotential of the gallium phase.

3. The crude gallium electrolytic refining device has simple structure, the electrolytic refining method has simple process, can continuously produce and has wide market application prospect.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic view of the structure of an electrolytic refining apparatus according to the present invention.

Fig. 2 is a schematic structural view of a flow channel in the spiral stepped flow channel structure of the present invention.

Illustration of the drawings:

1. an electrolytic cell; 2. an anode region; 3. a cathode region; 4. a spiral stepped flow passage structure; 5. a discharge valve; 6. an annular partition plate; 7. stirring the slurry; 71. a bottom layer paddle; 72. an upper paddle; 8. fluid infusion slag removal pipe.

Detailed Description

In order to facilitate an understanding of the invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.

Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.

The crude gallium used in the following examples had a Ga content of 99.948%, and contained major impurities including Zn 89ppm, Cu 63ppm, Mg 79ppm, and Pb 86 ppm.

Example 1:

as shown in fig. 1-2, the crude gallium electrorefining apparatus of the present embodiment includes an electrolytic cell 1, an anode region 2 for accommodating a crude gallium anode and a cathode region 3 for accommodating a high purity gallium cathode are disposed in the electrolytic cell 1, the anode region 2 and the cathode region 3 are independent of each other, the cathode region 3 is a spiral stepped flow channel structure 4, two sides and bottom of the flow channel of the spiral stepped flow channel structure 4 are closed, and an opening contacting with an electrolyte is disposed at the top.

Specifically, in this embodiment, the spiral stepped flow channel structure 4 is arranged along the inner side wall of the electrolytic tank 1, the flow channel width of the spiral stepped flow channel structure 4 gradually becomes wider from top to bottom, and the discharge valve 5 is arranged at the position, close to the bottom of the electrolytic tank 1, of the spiral stepped flow channel structure 4.

In the embodiment, an annular clapboard 6 is arranged at the center of the bottom of an electrolytic cell 1, and an anode area 2 is positioned inside the annular clapboard 6; the electrolytic refining device also comprises a stirring device, the stirring device comprises a stirring paddle 7 with double layers of paddles, the bottom layer paddle 71 is positioned in the anode region 2, and the upper layer paddle 72 is positioned above the anode region 2.

In this embodiment, the electrolytic refining device further includes a liquid supplementing and slag removing pipe 8, and one end of the liquid supplementing and slag removing pipe 8 is located in the anode region 2.

The electrolytic refining method for electrolyzing crude gallium in the embodiment comprises the following steps:

s1: respectively injecting liquid crude gallium (3N) and high-purity gallium (6N) into an anode region and a cathode region, immersing bare parts of platinum wire leads (5N) corresponding to the two electrodes in the liquid crude gallium and the high-purity gallium, and adding NaOH with the concentration of 90g/L, NaGaO into the electrolytic bath₂Electrolyte with concentration of 10g/L is stirred at 200rpm and 38 ℃ in water bath at 290A/m²The electrolysis is started under the current density, and the cell voltage is 2.9V;

s2: after electrolysis for a period of time, crude gallium can be supplemented to the anode region 2 through the liquid supplementing and slag removing pipe 8, scum possibly appearing on the surface of the anode region 2 can be absorbed, and a certain amount of electrolysis products can be discharged through the discharge valve 5 at the bottom of the cathode region 3;

s3: and (3) washing the electrolytic product for 0.5h by hydrochloric acid with the mass fraction of 10% and ultrapure water for two sections respectively under the conditions that the temperature is 55 ℃ and the magnetic stirring speed is 300rpm, and finally obtaining the high-purity gallium product.

In the embodiment, a large amount of hydrogen evolution side reactions do not occur in the electrolysis process, and the detection result shows that the purity of the washed final product reaches 6N, and the purification effect is obvious.

Example 2:

the apparatus for electrorefining crude gallium of this example was the same as in example 1.

The electrolytic refining method for electrolyzing crude gallium in the embodiment comprises the following steps:

s1: respectively injecting liquid crude gallium (3N) and high-purity gallium (6N) into an anode region and a cathode region, immersing bare parts of platinum wire leads (5N) corresponding to the two electrodes in the liquid crude gallium and the high-purity gallium, and adding NaOH with the concentration of 90g/L, NaGaO into the electrolytic bath₂Electrolyte with concentration of 10g/L is stirred at the rotation speed of 250rpm and the water bath heating temperature of 38 ℃ at 250A/m²The electrolysis is started under the current density, and the cell voltage is 2.6V;

s2: after electrolysis for a period of time, crude gallium can be supplemented to the anode region 2 through the liquid supplementing and slag removing pipe 8, scum possibly appearing on the surface of the anode region 2 can be absorbed, and a certain amount of electrolysis products can be discharged through the discharge valve 5 at the bottom of the cathode region 3;

s3: and respectively washing the electrolytic product for 1h by hydrochloric acid with the mass fraction of 12% and ultrapure water for two stages under the conditions that the temperature is 55 ℃ and the magnetic stirring speed is 300rpm, and finally obtaining the high-purity gallium product.

In the embodiment, a large amount of hydrogen evolution side reactions do not occur in the electrolysis process, and the detection result shows that the purity of the washed final product reaches 7N, and the purification effect is obvious.

Example 3:

the apparatus for electrorefining crude gallium of this example was the same as in example 1.

The electrolytic refining method for electrolyzing crude gallium in the embodiment comprises the following steps:

s1: respectively injecting liquid crude gallium (3N) and high-purity gallium (6N) into an anode region and a cathode region, immersing bare parts of platinum wire leads (5N) corresponding to the two electrodes in the liquid crude gallium and the high-purity gallium, and adding NaOH with the concentration of 90g/L, NaGaO into the electrolytic bath₂Electrolyte with concentration of 10g/L is stirred at 300rpm and water bath heating temperature of 38 ℃ at 200A/m²The electrolysis is started under the current density, and the cell voltage is 2.3V;

s2: after electrolysis for a period of time, crude gallium can be supplemented to the anode region 2 through the liquid supplementing and slag removing pipe 8, scum possibly appearing on the surface of the anode region 2 can be absorbed, and a certain amount of electrolysis products can be discharged through the discharge valve 5 at the bottom of the cathode region 3;

s3: and (3) washing the electrolytic product for 0.8h by 15 mass percent hydrochloric acid and ultrapure water in two stages respectively under the conditions that the temperature is 55 ℃ and the magnetic stirring speed is 300rpm, and finally obtaining the high-purity gallium product.

In the embodiment, a large amount of hydrogen evolution side reactions do not occur in the electrolysis process, and the detection result shows that the purity of the washed final product reaches 7N, and the purification effect is obvious.

Comparative example:

comparative examples A conventional cylindrical electrolytic gallium refining apparatus (having a cathode area of about 150 cm) was used for each of the comparative examples²) And in example 1, an electrolytic refining apparatus having a spiral stepped flow path structure 4 was used (cathode area about 400 cm)²) The concentration of NaOH is 90g/L, NaGaO₂And starting the electrolyte with the concentration of 10g/L, stirring at the rotation speed of 250rpm, heating in a water bath at the temperature of 38 ℃, electrolyzing for 10 hours at the current density of 250A/square meter, and washing cathode gallium by adopting the S3 washing operation in the example 3 after the electrolysis is finished, wherein the results show that the product purity of the electrolyte and the cathode gallium reaches 7N, and the final cathode product weight is 29.72g and 76.33g respectively, so that the electrolytic refining device with the spiral stepped flow channel structure 4 in the example 1 has an obvious effect under the electrolysis parameters.