A method for recovering and purifying gallium from seed liquor of aluminum plant

Abstract

The present invention belongs to the technical field of aluminum oxide production, and relates to a method for recovering and purifying gallium from seed and mother liquor of an aluminum plant, which comprises the following steps: S1: regulating the temperature of the seed and mother liquor, S2: obtaining saturated resin by adsorption, S3: washing the saturated resin with water, S4: analyzing the saturated resin, S5: evaporating, concentrating and freezing the analytical solution to obtain a solid-liquid mixture, S6: performing solid-liquid separation on the solid-liquid mixture, S7: obtaining an electrolytic stock solution, S8: electrolyzing the electrolytic stock solution to obtain crude gallium, S9: refining the crude gallium, and S10 collecting, weighing, packaging and storing gallium in a cold storage. The present invention improves the recovery rate and purity of gallium while reducing production costs and energy consumption. The heat exchanger can adjust the mother liquor temperature and the reflux mother liquor temperature; the improvement of the resin tower prolongs the service life of the resin, improves the resin utilization rate and reduces the cost; the cyclic adsorption of the tail liquid by the resin improves the recovery rate of gallium; the acid and alkali cyclic washing method greatly improves the purity of gallium.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum oxide production, and particularly relates to a method for recovering and purifying gallium from seed denominator liquor in an aluminum plant. Background Art

[0002] Gallium is a soft metal with a silvery white luster, usually associated with In, Ge, and Tl in bauxite and zinc sulfide ores. Due to its low melting point, extremely high boiling point, wide temperature range in which the metal remains liquid, low vapor pressure, ability to absorb neutrons, control reaction speed and other special properties, it is widely used as a heat exchanger in the atomic energy industry, such as semiconductor electronic materials, lasers, functional alloy materials, low-temperature superconducting materials, atomic energy industry and other fields. The industry is currently relatively stable and has promising prospects.

[0003] Gallium metal is mostly a by-product of alumina production. Usually, aluminum is separated by lime milk causticization, secondary carbon separation, organic solvent extraction or resin adsorption to obtain a gallium-rich solution, which is then prepared into an alkaline gallium-containing electrolyte solution and reduced and recovered by electrolysis.

[0004] At present, how to reduce the impurity content in gallium-rich solution and improve gallium recovery efficiency and purity on the basis of controlling energy consumption is the research and development direction and focus of existing technologies. The improvement and design of process methods are the most direct and intuitive technical means to solve the above technical problems. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a method for recovering and purifying gallium from aluminum plant seed liquor, which can reduce the impurity content in the gallium-rich solution, improve the recovery efficiency and purity of gallium, and improve the utilization rate of resources.

[0006] The present invention is achieved through the following technical solutions.

[0007] The present invention provides a method for recovering and purifying gallium from seed liquor of an aluminum plant, comprising the following process steps:

[0008] S1: Adjust the temperature of the seed liquor from the aluminum plant to 38℃~42℃;

[0009] S2: transporting the seed fraction solution into the resin tower so that gallium is adsorbed by the resin to obtain a saturated resin;

[0010] S3: Washing the mother liquor remaining on the surface of the saturated resin;

[0011] S4: using an analytical agent to analyze the saturated resin after washing, analyzing gallium into the analytical agent to obtain a gallium-containing analytical solution, and regenerating the resin at the same time;

[0012] S5: evaporating and concentrating the analytical solution to obtain a concentrated solution, and freezing the concentrated solution to obtain a solid-liquid mixture;

[0013] S6: performing solid-liquid separation on the solid-liquid mixture to obtain solution A and crystal A;

[0014] S7: using an oxidant to react with solution A to obtain an electrolytic solution;

[0015] S8: electrolyzing the electrolytic solution to obtain crude gallium;

[0016] S9: refining the crude gallium;

[0017] S10: Collect, weigh, package and store the refined gallium in a cold storage.

[0018] As a further improvement of the above scheme, in S1, the seed denominator liquid is heat exchanged through a heat exchanger to adjust the temperature to 40°C.

[0019] As a further improvement of the above scheme, in S2, the resin tower is divided into one tower layer, two tower layers, three tower layers and four tower layers according to volume, and a liquid distributor is provided between the two tower layers and the three tower layers.

[0020] As a further improvement of the above scheme, in S2, the seed mother liquid in the resin tower is fed from the bottom, and the first tower layer adsorbs the seed mother liquid; after the resin in the first tower layer is saturated with adsorption, the saturated resin is output for saturation washing, and at the same time, the resin of the second tower layer falls to the position of the first tower layer to directly contact the seed mother liquid, and the resin of the remaining towers falls down one layer accordingly; the adsorbed mother liquid is transported to the tail liquid tank.

[0021] As a further improvement of the above solution, the resin adsorption time in the first tower layer is 2 hours.

[0022] As a further improvement of the above scheme, in S3, the water washing includes saturated washing and overflow rinsing, the saturated resin is first saturated washed and then overflow rinsed; the saturated washing tail liquid after saturated washing is transported to the tail liquid tank; the overflow liquid of rinsing is discharged to the tail liquid tank; a resin recovery tank is set at the overflow outlet.

[0023] As a further improvement of the above scheme, in S4, the analysis includes: primary analysis: analyzing the saturated resin after water washing; secondary analysis: the analyzing agent analyzes the resin that has been analyzed once again; the analyzing agent is composed of liquid alkali, regeneration tail liquid, crystal dissolving liquid, and yellow alkali dissolving liquid; wherein the regeneration tail liquid is the tail liquid of the analyzing liquid in S4; the crystal dissolving liquid is the dissolving liquid of crystal A in S6.

[0024] As a further improvement of the above scheme, in S4, part of the resin regenerated after analysis is transported back to the resin tower, and the other part is transported to the tail liquid tank to adsorb gallium therein, and the saturated resin after adsorption is then subjected to the operation of S3.

[0025] As a further improvement of the above scheme, in S6, the oxidant is hydrogen peroxide.

[0026] As a further improvement of the above scheme, the refining in S9 includes the following steps: washing the crude gallium with dilute hydrochloric acid solution, water, NaOH solution, and water alone in sequence, and the above operation is repeated at least 3 times.

[0027] The beneficial effects achieved by the present invention are:

[0028] Compared with the prior art, the method for recovering and purifying gallium from the mother liquor of an aluminum plant of the present invention has an overall improvement, which reduces production costs and energy consumption while improving the recovery rate and purity of gallium. The setting of the heat exchanger ensures that the temperature of the mother liquor entering the production meets the production requirements, and can adjust the temperature of the reflux mother liquor according to the needs of the aluminum plant to avoid the fluctuation of the reflux mother liquor temperature affecting the normal production of the aluminum plant; the improvement of the resin tower prolongs the service life of the resin, improves the resin utilization rate, and greatly saves the resin cost; in addition, the recycling adsorption of the tail liquid by the resin further improves the recovery rate of gallium and the output of gallium, and the purity of gallium is greatly improved through the acid and alkali recycling washing method. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the process flow in the present invention;

[0030] Figure 2 It is a structural schematic diagram of the resin tower in the present invention.

[0031] In the figure: first tower layer 1, second tower layer 2, third tower layer 3, fourth tower layer 4, liquid distributor 5, mother liquor inlet 6, and adsorption mother liquor outlet 7. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0033] like Figure 1-Figure 2 As shown, the present invention provides a method for recovering and purifying gallium from seed liquor of an aluminum plant, comprising the following process steps:

[0034] S1: The temperature of the seed liquor from the aluminum plant is adjusted to 38°C to 42°C. In this embodiment, the seed liquor is heat exchanged through a heat exchanger to adjust the temperature to 40°C;

[0035] S2: The seed denominator liquid is transported into the resin tower, so that gallium is adsorbed by the resin to obtain saturated resin; specifically, the resin tower includes a first tower layer 1, a second tower layer 2, a third tower layer 3, and a fourth tower layer 4 according to volume. A liquid distributor 5 is arranged between the second tower layer 2 and the third tower layer 3. In this embodiment, the height of the resin tower cylinder is = 4.8m below the liquid distributor 5 + 4m above the liquid distributor 5, the diameter of the adsorption tower cylinder is 2.5m, and the volume of resin in each tower is 7.85m 3 The seed mother liquid in the resin tower is fed from the bottom, and the first tower layer 1 adsorbs the seed mother liquid. The resin adsorption time in the first tower layer 1 is 2 hours. After the resin in the first tower layer 1 is saturated with adsorption, the saturated resin is output for washing. At the same time, the resin in the second tower layer 2 falls to the position of the first tower layer 1 to directly contact the seed mother liquid, and the resins in the remaining towers fall one layer accordingly; the adsorbed mother liquid is transported to the tail liquid tank;

[0036] In practice, the resin will absorb vanadium while adsorbing gallium. By improving the resin tower, the impact of vanadium on the resin can be reduced, the service life of the resin can be extended, the resin utilization rate can be improved, and costs can be saved.

[0037] S3: washing the mother liquor remaining on the surface of the saturated resin with water. Specifically, the water washing includes saturated washing and overflow rinsing. The saturated resin is first saturated washed and then overflow rinsed. The saturated washing tail liquid after saturated washing is transported to the tail liquid tank, and the overflow liquid of rinsing is discharged to the tail liquid tank. A resin recovery tank is provided at the overflow outlet;

[0038] S4: using an analytical agent to analyze the washed saturated resin, analyzing gallium into the analytical agent to obtain a gallium-containing analytical solution, and regenerating the resin at the same time. Specifically, the analysis includes:

[0039] Primary analysis: analysis of saturated resin after water washing;

[0040] Secondary analysis: The analytical agent analyzes the resin that has been analyzed once again;

[0041] The analytical agent is composed of liquid alkali, regeneration tail liquid, crystal dissolving liquid, and yellow alkali dissolving liquid, wherein the regeneration tail liquid is the tail liquid of the analytical liquid in S4, and the crystal dissolving liquid is the dissolving liquid of crystal A in S6;

[0042] Part of the resin regenerated after analysis is transported back to the resin tower, and the other part is transported to the tail liquid tank to adsorb gallium in it. The saturated resin after adsorption is then subjected to the S3 operation;

[0043] S5: evaporating and concentrating the analytical solution to obtain a concentrated solution, and freezing the concentrated solution to obtain a solid-liquid mixture;

[0044] S6: performing solid-liquid separation on the solid-liquid mixture to obtain solution A and crystal A;

[0045] S7: using an oxidant to react with solution A to obtain an electrolytic solution, wherein the specific oxidant is hydrogen peroxide;

[0046] S8: electrolyzing the electrolytic solution to obtain crude gallium;

[0047] S9: refining the crude gallium; specifically, the refining comprises the following steps: washing the crude gallium with a dilute hydrochloric acid solution, water, a NaOH solution, and water alone in sequence, and the above operation is repeated at least 3 times;

[0048] S10: Collect, weigh, package and store the refined gallium in a cold storage.

[0049] The working process of the present invention is as follows: through a heat exchanger, the seed liquor from the aluminum plant that has been filtered is adjusted to a suitable production temperature (it can be adjusted from low temperature to high temperature, or from high temperature to low temperature. In this embodiment, a plate heat exchanger is used to adjust the seed liquor to 40°C to ensure production needs), and the temperature-adjusted seed liquor is transported to a mother liquor tank for storage. When it is put into production, the mother liquor is input from the mother liquor inlet 6 at the bottom of the resin tower through a delivery pump for adsorption. The mother liquor after resin adsorption overflows through the adsorption mother liquor outlet 7 at the upper position of the liquid distributor 5 and is discharged to the tail liquid tank.

[0050] After the adsorption is completed, there will inevitably be residual mother liquor attached to the surface of the resin. In order to wash away the residual mother liquor on the resin, the resin tower adsorbed saturated with resin is pressed into the saturation tower by compressed air for saturation washing. The saturation washing adopts new water downstream washing. The water enters from the top of the saturation tower and is discharged from the bottom. The saturated washing liquid is transported from top to bottom into the tail liquid tank.

[0051] Furthermore, in order to remove fine impurities in the resin (such as aluminum hydroxide particles, small resins and damaged resins, etc.), the saturated resin is pressed into the rinsing tower by compressed air for countercurrent overflow rinsing. Water enters the rinsing tower from the bottom and overflows from the top. The rinsing overflow liquid is discharged into the tail liquid tank, and the rinsing tail liquid is transported to the sewage treatment station.

[0052] Furthermore, in order to prevent part of the resin from being carried away during the rinsing overflow process, a resin recovery tank is provided at the overflow outlet, and the recovered resin re-enters the rinsing tower for rinsing.

[0053] After rinsing, the resin is pressed into the analytical tower by compressed air, and the gallium on the saturated resin is analyzed into the analytical agent by eluting with the analytical agent, so that the resin can be regenerated while generating a pure analytical agent with a high gallium content.

[0054] Specifically, the analytical agent is prepared by uniformly stirring water, liquid alkali, regeneration tail liquid, crystal dissolving liquid, and yellow alkali (containing 60% Na2S and 32% H2O) dissolving liquid in a preparation tank with a stirrer. The prepared analytical agent is transported to the analytical liquid tank. Before the analytical agent is put into use, necessary sampling and testing are required to ensure that the analytical agent meets production requirements.

[0055] Among them, the liquid caustic soda comes from the liquid caustic soda intermediate tank and is transported to the preparation tank through the liquid caustic soda pump;

[0056] The regeneration tail liquid comes from the regeneration tail liquid tank, mainly from the analytical tail liquid of the analytical tower;

[0057] Crystal dissolving liquid, coming from a crystal dissolving tank, mainly sodium sulfide crystal dissolving liquid;

[0058] Furthermore, the analysis process adopts a rinsing method to perform secondary washing analysis.

[0059] Specifically, the first analysis is to wash the saturated resin from the rinsing tower with an analytical agent in the first analysis tower, and the second analysis is to perform a secondary analysis on the resin after the first analysis tower in the second analysis tower. The overflow liquid of the analysis tower is transported to the sewage treatment station, and the analysis tail liquid is transported to the regeneration tail liquid tank.

[0060] Furthermore, part of the lean resin obtained after analysis is transported back to the resin tower, and the other part is transported to the tail liquid tank mentioned above to adsorb gallium therein. The saturated resin after adsorption in the tail liquid tank is transported to the rinsing tower for rinsing, and the adsorbed tail liquid is transported back to the aluminum plant.

[0061] Furthermore, a heat exchanger is installed on the return pipe of the aluminum plant. In this embodiment, it is a plate heat exchanger, which can adjust the temperature of the materials returned to the aluminum plant to meet the production needs of the aluminum plant.

[0062] The qualified gallium-containing analysis liquid obtained after analysis by the analysis tower is transported to the evaporator for evaporation. The steam used in this embodiment comes from the steam in the evaporation workshop of the aluminum plant, with a steam pressure of 0.6Mpa and a temperature of 180°C. The evaporated liquid (i.e., concentrated liquid) is transported to the concentrated liquid tank, and the qualified concentrated liquid that has been tested is sent to the freezing tank for freezing through a concentration pump to freeze the sodium sulfide into crystals. The freezing temperature is controlled at -3°C to 0°C, and the temperature of the evaporated liquid is 80°C. It is naturally cooled, and the 80°C solution is naturally cooled to 40 degrees using a cooling tower (air cooling), and then frozen to -3°C to 0°C using a refrigerator.

[0063] The frozen crystal and liquid mixture are subjected to solid-liquid separation. In this embodiment, a belt filter is used to separate the solid and liquid, and crystal A and solution A are obtained.

[0064] Among them, crystal A is transported to the crystal dissolution tank and sent to the preparation tank together with the yellow alkali dissolution solution to prepare the analytical agent.

[0065] Furthermore, the regenerated tail liquid in the regenerated tail liquid tank is used to clean the crystal A, the cleaned crystal is transported to the crystal dissolution tank, the crystal washing water is transported to the crystal washing water tank, the crystal washing water is then transported to the evaporator for evaporation to generate a concentrated liquid, thereby reducing the circulation of gallium, and the concentrated liquid is then sent to the freezing tank.

[0066] The solid-liquid separated solution A is transported to the filtrate tank, and then pumped to the oxidation tank by the filtrate pump.

[0067] After condensation and crystallization, most of the sodium sulfide has been precipitated to form sodium sulfide crystals, but there is still a small amount of sodium sulfide that needs to be removed by oxidation. The purpose of oxidation is to remove the S 2- Oxidized to SO4 2- In this embodiment, hydrogen peroxide is used as the oxidant, which is stored in a hydrogen peroxide storage tank.

[0068] Solution A undergoes an oxidation reaction with hydrogen peroxide to generate an electrolytic stock solution, which is then transported to an electrolytic stock solution tank.

[0069] The electrolyte stock solution is transported to the electrolytic cell by an electrolyte stock solution pump for electrolysis, and the gallium in the electrolyte stock solution containing sodium gallate is electrolyzed into single metallic gallium.

[0070] Furthermore, after the electrolysis reaction is completed, crude gallium (Ga) and a small amount of hydrogen (H2) are generated at the cathode, oxygen (O2) is generated at the anode, and the remaining electrolytic tail liquid is discharged into the electrolytic tail liquid tank and finally pumped to the tail liquid tank by the electrolytic tail liquid pump, and crude gallium is discharged from the bottom of the electrolytic tank.

[0071] The crude gallium obtained by electrolysis has a large amount of impurities in its oxide film. Gallium is slightly soluble in hydrochloric acid, and some impurities in gallium will quickly dissolve in acid and alkali at room temperature. Therefore, this characteristic of gallium can be used to selectively dissolve metal impurities in it. Treatment with hydrochloric acid can remove or reduce impurities such as zinc, aluminum, iron, calcium, and magnesium. Hydrogen and oxygen are then used to dissolve impurities in gallium that are insoluble in hydrochloric acid and to neutralize excess hydrochloric acid, thereby obtaining higher purity metallic gallium. Waste acid and waste alkali generated during the refining process are recovered and centrally treated.

[0072] Specifically, the crude gallium is first washed with pure water and then placed in a washing container. Three equivalents of dilute hydrochloric acid (36% reagent hydrochloric acid configuration) are poured into the washing container. The dilute hydrochloric acid and the crude gallium are fully contacted and mixed by a vibrating device or a stirring device (the washing temperature is controlled at 40°C), and the gallium after acid washing is taken out and washed with pure water. The washed gallium is placed in a washing container, and 3 equivalents of NaOH solution (96% reagent sodium hydroxide configuration) are added for alkaline washing. The NaOH solution and the crude gallium are fully contacted and mixed by a vibrating device or a stirring device, and the alkaline washing is completed. The gallium after acid washing is taken out and washed with pure water. The above acid washing and alkaline washing steps are repeated three times to complete the refining and purification of gallium to obtain 4N gallium.

[0073] The refined and purified gallium is weighed, packaged into packaging bottles, placed in a cold storage and stored frozen.

[0074] The above describes in detail the implementation modes of the present invention in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes. The implementation modes can still be changed within the knowledge scope of ordinary technicians in the field. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for recovering and purifying gallium from seed liquor of an aluminum plant, characterized in that: The process steps include: S1: Adjust the temperature of the seed liquor from the aluminum plant to 38℃~42℃; S2: The seed denominator liquid is transported into the resin tower so that gallium is adsorbed by the resin to obtain a saturated resin; in S2, the resin tower is divided into a first tower layer (1), a second tower layer (2), a third tower layer (3), and a fourth tower layer (4) according to volume, and a liquid distributor (5) is arranged between the second tower layer (2) and the third tower layer (3); in S2, the seed denominator liquid in the resin tower is fed from the bottom, and the first tower layer (1) adsorbs the seed denominator liquid; after the resin in the first tower layer (1) is saturated with adsorption, the saturated resin is output for saturation washing, and at the same time, the resin in the second tower layer (2) falls to the position of the first tower layer (1) to directly contact the seed denominator liquid, and the resins in the remaining towers fall one layer accordingly; the adsorbed denominator liquid is transported to the tail liquid tank; S3: washing the mother liquor remaining on the surface of the saturated resin; in S3, the water washing includes saturated washing and overflow rinsing, the saturated resin is first saturated washed and then overflow rinsed; the saturated washing tail liquid after saturated washing is transported to the tail liquid tank; the overflow liquid of rinsing is discharged to the tail liquid tank; a resin recovery tank is provided at the overflow outlet; S4: Use an analytical agent to analyze the saturated resin after water washing, analyze gallium into the analytical agent, obtain a gallium-containing analytical solution, and regenerate the resin at the same time; in S4, the analysis includes: primary analysis: analyzing the saturated resin after water washing; secondary analysis: the analytical agent analyzes the resin that has been analyzed once again; the analytical agent is configured by liquid alkali, regeneration tail liquid, crystal dissolving liquid, and yellow alkali dissolving liquid; wherein the regeneration tail liquid is the tail liquid of the analytical solution in S4; the crystal dissolving liquid is the dissolving liquid of crystal A in S6; in S4, part of the resin regenerated after analysis is transported back to the resin tower, and the other part is transported to the tail liquid tank to adsorb gallium therein, and the saturated resin after adsorption is then subjected to the operation of S3. S5: evaporating and concentrating the analytical solution to obtain a concentrated solution, and freezing the concentrated solution to obtain a solid-liquid mixture; S6: performing solid-liquid separation on the solid-liquid mixture to obtain solution A and crystal A; S7: using an oxidant to react with solution A to obtain an electrolytic solution; in S7, the oxidant is hydrogen peroxide; S8: electrolyzing the electrolytic solution to obtain crude gallium; S9: Refining the crude gallium; the refining in S9 comprises the following steps: washing the crude gallium with dilute hydrochloric acid solution, water, NaOH solution, and water alone in sequence, and the above operation is repeated at least 3 times S10: Collect, weigh, package and store the refined gallium in a cold storage.

2. The method for recovering and purifying gallium from aluminum plant seed liquor according to claim 1, characterized in that: In S1, the seed liquor is heat exchanged through a heat exchanger to adjust the temperature to 40°C.

3. The method for recovering and purifying gallium from aluminum plant seed liquor according to claim 1, characterized in that: The resin adsorption time in the first tower layer (1) is 2 hours.

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