Highly efficient base desorption method for amidoxime gallium adsorption resin

Abstract

The application discloses a new method for efficiently desorbing gallium from saturated and adsorbed amidoamine resin in an alkaline medium. In order to solve the technical bottleneck existing in the alkaline elution of the gallium adsorption resin, the application provides a new method for enriching gallium from a Bayer process alumina production mother liquor by using amidoamine resin, then realizing efficient desorption of the gallium in an alkaline medium, and finally preparing a gallium-rich solution for electrolysis. The method adopts polysulfide-chelation composite eluent, can replace the traditional sodium sulfide-sodium hydroxide eluent, can effectively improve the desorption efficiency of the amidoamine gallium adsorption resin, can improve the service life of the chelation resin, can reduce the overall cost of extracting elemental gallium from the Bayer process mother liquor, and can effectively connect with the strong alkaline Bayer process aluminum extraction process.

Description

TECHNICAL FIELD

[0001] The application relates to an alkali desorption method of high-efficiency amidoamine gallium adsorption resin and belongs to the field of hydrometallurgy. BACKGROUND

[0002] Gallium is a kind of rare metal with unique physical and chemical properties, which is widely used in the fields of semiconductor manufacturing, solar cells, low-melting-point alloys, special optical glass and the like. In recent years, with the rapid development of economy, the global demand for gallium continues to increase, the market gap continues to expand, and the price of gallium continues to rise.

[0003] Gallium is difficult to form ore independently and mainly exists in other minerals in the form of a rare metal. Gallium mainly comes from bauxite, sphalerite and coal processing processes, and is recovered in the form of a by-product. At present, about 90% of gallium in the world is extracted from the strong alkaline circulating mother liquor of the Bayer process for producing aluminum. Although the abundance of gallium in most bauxite is only dozens of ppm, gallium will continuously enrich in the circulating mother liquor along with the continuous dissolution of aluminum from bauxite in the Bayer process for extracting aluminum, so that the concentration of gallium in the mother liquor is as high as 100-300 ppm.

[0004] The extraction of gallium from the Bayer process mother liquor includes two steps of gallium enrichment and electrolysis of the gallium-rich solution to produce gallium. Among them, the technology involved in the enrichment of gallium from the mother liquor is the most critical. As of now, the industry generally considers that the most economical and effective method for mother liquor enrichment (GaO2 - ) is to use chelating resin to selectively adsorb gallium from the mother liquor with extremely complex components to realize the effective separation of gallium. The chelating resin is formed by the combination of a resin skeleton and a chelating functional group in the form of a chemical bond, and is a kind of exchange resin with high selectivity. Among them, the application of amidoamine resin in the enrichment process of gallium-containing mother liquor is the most widespread. The O and N in the amidoamine functional group (-C=NOH) carried on the skeleton of the chelating resin form a coordination bond with Ga through the lone pair of electrons and finally form a stable structure similar to small molecule chelates, which has the advantages of large adsorption capacity, good stability and relatively small interference in strong alkaline solution.

[0005] Effective desorption of gallium from saturated adsorbed amylopectin resins directly impacts the cost of the gallium enrichment process. The desorption stage constitutes the majority of the overall cost of gallium extraction from Bayer's mother liquor process. Gallium-containing resin desorption can be categorized into acidic and alkaline desorption. In acidic media, gallium desorption from the adsorbed resin is highly efficient and fast; however, in acidic eluents, the amylopectin functional groups readily react with protons, leading to deactivation and accelerated resin depletion, necessitating frequent resin replacement. Alkaline elution techniques, such as sodium sulfide-sodium hydroxide elution, significantly extend the lifespan of amylopectin resins and are easily integrated with the aluminum extraction process in the strongly alkaline media of the Bayer process, but they result in low gallium desorption rates and noticeably slow desorption kinetics. Summary of the Invention

[0006] To address the technical bottlenecks of current gallium adsorption resins under alkaline elution conditions, this invention provides a novel method for enriching gallium from Bayer process alumina production mother liquor using a metallo-oxime resin, followed by efficient gallium desorption in an alkaline medium, and finally preparing a gallium-rich solution for electrolysis. This method employs a polysulfide-chelate composite eluent, which can replace the traditional sodium sulfide-sodium hydroxide eluent, effectively improving the desorption efficiency of the metallo-oxime gallium adsorption resin, extending the service life of this type of chelate resin, reducing the overall cost of extracting elemental gallium from Bayer process mother liquor, and enabling effective integration with the strongly alkaline Bayer process alumina extraction process.

[0007] A novel, highly efficient alkaline desorption method for gallium oxime adsorption resins is performed according to the following steps: (1) Preparation of polysulfide-chelate composite eluent: Under air-isolated conditions, a certain amount of sodium sulfide nonahydrate and elemental sulfur (molar ratio 1:1) were added to a reactor containing 1 cubic meter of oxygen-free water. The mixture was continuously stirred at 100 rpm and slowly heated to 50-75°C. The mixture was stirred at a constant temperature for 8-15 hours until the elemental sulfur was completely dissolved, thus preparing a 0.1-2 M polysulfide solution. Subsequently, a certain amount of ethylenediaminetetraacetic acid (EDTA) or nitrotriacetic acid (NTA) was added to the polysulfide solution, and the final concentrations of EDTA and NTA were controlled within the range of 0.01-0.5 M.

[0008] (2) Enrichment of gallium in mother liquor by chelating resin: Amidoxime resin was packed into an ion exchange column. The feed temperature was controlled at 20-30℃, and the vanadium-removed Bayer process circulating mother liquor was fed into the exchange column from bottom to top. Under the condition of empty column linear velocity of 1-15 m / h, the feed was fed for 0.5-10 hours until the resin reached more than 80% saturation adsorption, and then the feed to the adsorption column was turned off. The vanadium content in the vanadium-removed circulating mother liquor should be controlled below 20 mg / L or gallium concentration below 10% to reduce the interference of vanadium on gallium adsorption on the resin and improve gallium adsorption efficiency.

[0009] (3) Water washing: After the resin reaches 80% or more of saturation adsorption, deionized water is introduced from the bottom of the exchange column to remove the residual vanadium removal mother liquor between the resin particles. Water washing is stopped when the pH of the outlet solution drops below 9. The water washing solution is returned to the vanadium removal mother liquor.

[0010] (4) Desorption of saturated gallium adsorption resin: Control the empty column linear velocity at 1-10 m / h and at 20-30℃, pass the prepared polysulfide-chelate composite eluent from below the saturated adsorption column, and collect the gallium-rich desorbed solution into a buffer tank. Add hydrogen peroxide to the buffer tank, control the temperature to remove impurities, and electrolyze the purified gallium-rich electrolyte to prepare metallic gallium; (5) Gallium-depleted resin regeneration: Deionized water is introduced from below the gallium-depleted resin exchange column at a blank column velocity of 1-15 m / h to remove the eluent remaining on the column and resin surface. Water washing is stopped when the pH of the outlet liquid drops below 9. The collected eluent solution is returned to the polysulfide-chelate composite eluent storage tank or the eluent concentration adjustment tank. At this point, the gallium-depleted resin regeneration is complete, and it enters the next gallium adsorption cycle. Detailed Implementation

[0011] Example 1: (1) The gallium content of a certain Bayer process alumina production mother liquor was measured to be 280 ppm after vanadium removal treatment; (2) Pretreatment of chelating resin: LSC-600 oxime resin was soaked in 1 M sodium hydroxide solution at room temperature for 24 h, and then washed and soaked with deionized water for activation before use.

[0012] (3) Preparation of polysulfide-chelate composite eluent: Under anaerobic conditions, to 1 m 3 Sodium sulfide nonahydrate and elemental sulfur (molar ratio 1:1) were added to anoxic water. The solution was heated to 75°C with stirring at 100 rpm and stirred at this temperature for 8 hours until the elemental sulfur was completely dissolved, thus preparing a 1.5 M polysulfide solution. NTA was then added to the prepared polysulfide solution to achieve a concentration of 0.05 M.

[0013] (4) LSC-600 enrichment of gallium in mother liquor: The activated resin was loaded into the exchange column. At 25°C, the vanadium-removing circulating mother liquor of 280 ppm was fed into the exchange column from bottom to top. The feed was carried out for 5 hours at a blank column velocity of 1 m / h until the resin reached 87% saturation.

[0014] (5) Water washing: Deionized water is passed from bottom to top through the saturated adsorption column to remove the mother liquor remaining between the resin particles. The washing is stopped when the pH reaches 8.6.

[0015] (6) Desorption of saturated gallium-absorbing resin: The empty column linear velocity was controlled at 2 m / h. At 25°C, the polysulfide-chelate composite eluent prepared above was introduced from below the adsorption column, and the gallium-rich desorbate was collected into a buffer tank. Hydrogen peroxide was added to the buffer tank, and impurities were removed by controlling the temperature. The purified gallium-rich electrolyte contained 4.9 g / L of gallium. (7) Gallium-depleted resin regeneration: Deionized water is introduced from below the resin column at a linear velocity of 3 m / h to remove residual eluent from the column and resin surface. The rinsing and regeneration washing is stopped when the pH of the outlet liquid reaches 8.5. The collected eluent solution is returned to the polysulfide-chelate composite eluent conditioning tank and the eluent concentration is adjusted. At this point, the gallium-depleted resin has completed regeneration and enters the next gallium adsorption cycle.

[0016] Example 2: (1) The gallium content of a certain Bayer process alumina production mother liquor was measured to be 312 ppm after vanadium removal treatment; (2) Preparation of polysulfide-chelate composite eluent: Under anaerobic conditions, sodium sulfide nonahydrate and elemental sulfur solid (molar ratio 1:1) were added to 1 cubic meter of oxygen-free water. The solution was heated to 70°C under stirring at 100 rpm and stirred at a constant temperature for 9 hours until the elemental sulfur was completely dissolved, thus preparing a 2 M polysulfide solution. EDTA was added to the prepared polysulfide solution to achieve a concentration of 0.025 M.

[0017] (3) Enrichment of gallium in mother liquor by LSC-600: The activated LSC-600 oxime resin was loaded into the exchange column. At 25°C, the vanadium-removing circulating mother liquor with a concentration of 312 ppm was fed into the exchange column from bottom to top. The feed was carried out for 7 hours at a blank column velocity of 1.2 m / h until the resin reached 91% saturation.

[0018] (4) Water washing: Deionized water is passed from bottom to top through the saturated adsorption column to remove the residual mother liquor between the resin particles. The washing is stopped when the pH reaches 8.5.

[0019] (5) Desorption of saturated gallium-absorbing resin: The empty column linear velocity was controlled at 1.5 m / h, and the polysulfide-chelate composite eluent prepared above was introduced from below the adsorption column at 25°C. The gallium-rich desorbed solution was collected into a buffer tank. Hydrogen peroxide was added to the buffer tank, and the temperature was controlled to remove impurities. The purified gallium-rich electrolyte contained 5.3 g / L of gallium. (6) Gallium-depleted resin regeneration: Deionized water is introduced from below the resin column at a linear velocity of 3 m / h to remove the eluent remaining on the column and resin surface. The rinsing and regeneration are stopped when the pH of the outlet liquid reaches 8.4. At this point, the gallium-depleted resin has completed regeneration and enters the next gallium adsorption cycle.

Claims

1. A highly efficient alkaline desorption method for gallium oxime adsorption resin, characterized in that, Includes the following steps: (1) Preparation of polysulfide-chelate composite eluent: Under air-isolated conditions, a certain amount of sodium sulfide nonahydrate and elemental sulfur (molar ratio 1:1) were added to a reactor containing 1 cubic meter of oxygen-free water. The mixture was continuously stirred at 100 rpm and slowly heated to 50-75°C. The mixture was stirred at a constant temperature for 8-15 hours until the elemental sulfur was completely dissolved, thus preparing a 0.1-2 M polysulfide solution. Subsequently, a certain amount of ethylenediaminetetraacetic acid (EDTA) or nitrilotriacetic acid (NTA) was added to the polysulfide solution, and the final concentrations of EDTA and NTA were controlled within the range of 0.01-0.5 M. (2) Enrichment of gallium in mother liquor by chelating resin: A chelate oxime resin was packed into an ion exchange column. The feed temperature was controlled at 20-30℃, and the vanadium-removed Bayer process circulating mother liquor was fed into the exchange column from bottom to top. Under an empty column velocity of 1-15 m / h, the feed was continued for 0.5-10 hours until the resin reached saturation adsorption of over 80%, and then the feed to the adsorption column was turned off. The vanadium content in the vanadium-removed circulating mother liquor needed to be controlled below 20 mg / L or below 10% of the gallium concentration to reduce the interference of vanadium on gallium adsorption on the resin and improve the gallium adsorption efficiency. (3) Water washing: After the resin reaches 80% or more of saturated adsorption, deionized water is introduced from the bottom of the exchange column to remove the residual vanadium removal mother liquor between the resin particles. Water washing is stopped when the pH value of the outlet solution drops to 8-9; the water washing liquid is returned to the vanadium removal mother liquor. (4) Desorption of saturated gallium adsorption resin: Controlling the empty column linear velocity at 1-10 m / h and the temperature at 20-30℃, the polysulfide-chelate composite eluent prepared above is introduced from below the saturated adsorption column, and the gallium-rich desorbate is collected into a buffer tank. Hydrogen peroxide is added to the buffer tank, and impurities are removed by temperature control. The purified gallium-rich electrolyte is then electrolyzed to prepare metallic gallium. (5) Gallium-depleted resin regeneration: Deionized water is passed through the bottom of the gallium-depleted resin exchange column at a blank column velocity of 1-15 m / h to remove residual eluent on the column and resin surface. Water washing is stopped when the pH of the outlet liquid reaches 8-9. The collected eluent solution is returned to the polysulfide-chelate composite eluent storage tank or the eluent concentration adjustment tank. At this point, the gallium-depleted resin regeneration is complete, and it enters the next gallium adsorption cycle.

2. The novel method according to claim 1, characterized in that: Step (1) Preparation of the polysulfide-chelate composite eluent involves reacting elemental sulfur with sodium sulfide at 50-75°C in the absence of air to generate polysulfides, which are then combined with subsequently added EDTA or NTA (0.01-0.5 M) to form a novel base desorbent. This desorbent strongly complexes with GaO2 adsorbed on the oxime groups of the amylopyramine. - It has excellent desorption capabilities, which can effectively improve the desorption efficiency of gallium oxime adsorption resin in alkaline media, extend the service life of the resin, reduce the overall cost of extracting elemental gallium from Bayer process mother liquor, and can be effectively integrated with the strongly alkaline Bayer process for aluminum extraction.