A method for extracting germanium and rhenium from coal conversion ash

Abstract

The application discloses a method for extracting germanium and rhenium from coal conversion ash. The method first separates the coal conversion ash by flotation to obtain carbon and tail ash; the tail ash is mixed with an auxiliary agent and subjected to thermal activation treatment within a set temperature range; after cooling, the mixture is subjected to water leaching and filtration to obtain a leaching solution containing germanium and rhenium; through extraction, evaporation and chemical treatment steps, germanium and rhenium are separated and purified, and finally high-purity germanium and rhenium products are obtained. The method improves the extraction efficiency of germanium and rhenium, the recovery rate of the germanium product reaches 88%, the purity is 96%, the recovery rate of the rhenium product reaches 92%, the purity is 98%, the process is environmentally friendly, the economic benefit is remarkable, and the comprehensive utilization of coal-based solid waste is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mineral extraction, in particular to a method for extracting germanium from chlorination distillation residues. BACKGROUND

[0002] Coal conversion ash is a solid waste produced in the process of coal conversion, such as coal gasification ash produced in the process of coal gasification, or fly ash produced in the process of power generation of germanium-containing lignite. At present, the main uses of coal conversion ash include structural backfill, roadbed filling, and use as building materials, etc. The utilization mode is relatively single, and the effective treatment degree is not high. Coal conversion ash contains rich germanium and rhenium and other rare metals. These metals have important application value in the fields of electronics, optics, aerospace, etc. Due to the extremely low content and complex distribution of germanium and rhenium in coal conversion ash, it is difficult to extract them efficiently. Research on the extraction of germanium and rhenium from coal conversion ash has practical value and important significance for realizing the resource utilization of solid waste.

[0003] The most commonly used method for extracting metal elements from coal conversion ash is acid extraction process, which is simple, but the acid consumption is generally large. Therefore, it is urgent to develop a method for extracting germanium and rhenium from coal conversion ash with small acid consumption, high product purity and high extraction efficiency. SUMMARY

[0004] The purpose of the present application is to provide a method for extracting germanium and rhenium from coal conversion ash, which has the advantages of small acid consumption, high product purity and high extraction efficiency.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows: a method for extracting germanium and rhenium from coal conversion ash, comprising the following steps:

[0006] S1. Floatation separation of coal conversion ash to obtain residual carbon and tail ash; the coal conversion ash is fly ash or coal gasification ash;

[0007] S2. Mix the tail ash and the auxiliary agent uniformly, and perform heat activation treatment in a set temperature range; the auxiliary agent is sodium hydroxide or calcium hydroxide;

[0008] S3. Cool the mixture after heat activation treatment to room temperature, and then perform leaching and filtration to obtain a germanium and rhenium-containing leaching solution;

[0009] S4. Separate and process the germanium and rhenium in the leaching solution to obtain preliminarily purified germanium and a rhenium-rich solution; the specific operation is: (1) extraction: mix the leaching solution with ethyl acetate at a volume ratio of 1:1, stir to dissolve the germanium and rhenium in the ethyl acetate, separate the organic phase and the aqueous phase after standing for 20-30 min, and repeat the extraction step 3-5 times;

[0010] (2) Evaporation: the organic phase after extraction is evaporated to 10-12% of the original solution volume, concentrating the germanium and rhenium solution;

[0011] (3) Separation of germanium: 1 mol / L hydrogen peroxide is slowly added to the concentrated solution while stirring, so that germanium ions are oxidized to GeO2 precipitate;

[0012] After the oxidation reaction is completed, the mixture is kept still for 1-2 hours, the precipitate is separated, washed, and dried to obtain the germanium precipitate; rhenium ions are oxidized to peroxo-rhenate, and the solution obtained by separating the germanium precipitate is the rhenium solution;

[0013] S5. The preliminarily purified germanium is subjected to purification treatment, and the rhenium solution is subjected to purification treatment to obtain high-purity germanium and rhenium; the specific operation is as follows: (1) Purification of germanium: the dried germanium precipitate is placed into a reduction furnace, hydrogen is introduced, the temperature is controlled to be 700-900°C, and the mixture is kept for 2-4 hours to generate high-purity germanium product;

[0014] (2) Purification of rhenium: 30% ammonia water by mass concentration is slowly added to the rhenium-containing solution, the mixture is continuously stirred at room temperature, and the pH is controlled to be 7-8; the white precipitate generated in the reaction is ammonium rhenate;

[0015] The precipitate is separated, washed, and dried; the dried rhenium precipitate is placed into a reduction furnace, hydrogen is introduced, the temperature is controlled to be 800-1000°C, and the mixture is kept for 3-5 hours to generate high-purity rhenium product.

[0016] Preferably, in step S1, before the coal conversion ash flotation separation, ore grinding treatment is performed: the carbon-ash is ground for 10-40 min under the ore grinding concentration of 25%-45% to fully separate the carbon-ash.

[0017] Preferably, in step S2, the mass ratio of tail ash to auxiliary agent is 1:0.8-1.8, the temperature of the thermal activation treatment is 500-700°C, the temperature rising rate is 5-12°C / min, and the time is 1-4 hours.

[0018] Preferably, in step S3, the leaching conditions are as follows: deionized water is used as the leaching agent, the liquid-solid ratio (6-10):1 L / kg of the mixture after the thermal activation treatment is used for leaching, and the mixture is stirred at 300-800 r / min for 2-5 hours.

[0019] Preferably, in operation (1) of step S4, the stirring rate of extraction is 300-500 r / min.

[0020] Preferably, in operation (3) of step S4, the temperature for drying the precipitate is 50-60°C, and the time is 6 hours.

[0021] Preferably, in operation (2) of step S5, the temperature for drying the precipitate is 80-100°C.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] (1) The present application makes the germanium and rhenium components in the coal conversion ash more easily extracted by adding a specific additive to the coal conversion ash and performing a thermal activation treatment, significantly improving the extraction efficiency of germanium and rhenium compared to the traditional mechanical grinding and acid leaching method.

[0024] (2) The present application uses water as the leaching agent, avoiding the use of acid solution, reducing the problems of waste acid treatment and environmental pollution, and fundamentally reducing the impact on the environment.

[0025] (3) By optimizing the thermal activation and leaching conditions, the present application reduces the amount of chemical reagents used, reduces the overall processing cost, and improves economic efficiency.

[0026] (4) The process flow of the present application is simple and efficient, and through thermal activation treatment and simple leaching and purification steps, efficient extraction of germanium and rhenium is achieved, with fewer operation steps and lower difficulty.

[0027] (5) The present application optimizes the leaching process, reduces the generation of waste liquid, and the generated leaching residue is easy to handle, reducing the difficulty of waste residue and waste liquid treatment. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a process flow diagram in Example 1 of the present application. DETAILED DESCRIPTION

[0029] The present application will be further described in detail below in combination with the drawings and specific examples.

[0030] A coal gasification ash produced by a certain coal chemical enterprise was used as the raw material, and the germanium and rhenium content of the coal conversion ash was: germanium 9.6 g / t, rhenium 1.3 g / t. The coal gasification ash was comprehensively utilized by using the method of the present application.

[0031] The process flow is shown in Figure 1 , and the operation is as follows:

[0032] After the coal gasification ash was dried, the coal gasification ash was ground in a rod mill for 40 min at a grinding concentration of 40%, so that the carbon-ash was fully separated, and then the residual carbon and tail ash were obtained by flotation;

[0033] Then, the additive was added at a ratio of tail ash to additive weight ratio of 1:1.2, the additive was sodium hydroxide, and the tail ash and the additive were fully mixed to ensure uniform mixing.

[0034] The mixed fly ash and additives are placed in a high-temperature furnace, the temperature is set to 700°C, the heating rate is 8°C / min, and the heat activation treatment is performed for 4 hours. During the treatment, the mixture is stirred regularly to ensure uniform heating. After the heat activation treatment, the germanium and rhenium components in the fly ash are more active and easier to extract subsequently.

[0035] After the heat activation treatment, the mixture is cooled to room temperature, and then leaching treatment is performed. The leaching conditions are as follows: deionized water is used as the leaching agent, the liquid-solid ratio of deionized water to the heat-activated mixture is 7:1 L / kg, and the leaching operation is performed with stirring at 500 r / min for 2-5 hours. After the treatment, the leaching solution is obtained by filtration.

[0036] The leaching solution is mixed with ethyl acetate at a volume ratio of 1:1, stirred at 400 r / min for 30 minutes, and then separated into organic and aqueous phases after standing for 30 minutes. The organic phase after extraction is placed in a rotary evaporator, and the ethyl acetate is evaporated under the conditions of 40°C and -0.09 MPa until the solution volume is reduced to 10% of the original volume.

[0037] The concentrated solution is slowly added to hydrogen peroxide (1 mol / L) with constant stirring. After the oxidation reaction is completed, the mixture is kept still for 1-2 hours to allow the germanium dioxide to precipitate. The precipitate and the solution are separated by a vacuum filter, the precipitate is washed with deionized water for 3 times, and then dried at a temperature of 60°C for 6 hours. The chemical reaction equation is as follows:

[0038] Ge 2+ + H2O2→ GeO2↓ + 2H +

[0039] The dried germanium precipitate is placed in a reduction furnace, hydrogen gas is introduced, the temperature is controlled at 800°C, and the process is maintained for 4 hours to generate germanium products with a purity of 96% and a recovery rate of 88%. The reaction equation is as follows:

[0040] GeO2 + 2H2→ Ge + 2H2O

[0041] The rhenium ions are oxidized to peroxorhenate, and the solution obtained by separating the germanium precipitate is the rhenium solution. Ammonia water with a mass concentration of 30% is slowly added to the rhenium-containing solution, and the mixture is stirred constantly at room temperature to control the pH value at 7-8. The white precipitate produced in the reaction is ammonium rhenate. The chemical reaction equation is as follows:

[0042] HReO4 + NH3·H2O→ NH4ReO4 + H2O

[0043] The precipitate is separated using a vacuum filter, washed with deionized water to remove impurities and residual liquid attached to the surface, and dried in an oven at a temperature of 100°C to ensure that the precipitate is dry and free of moisture.

[0044] The dried rhenium precipitate is put into a reduction furnace, hydrogen is passed in, the temperature is controlled at 950 DEG C, and is kept for 4 hours, a rhenium product with purity of 98% is generated, and the recovery rate of the rhenium product reaches 92%. The reaction equation is as follows:

[0045] 2NH4ReO4+7H2→2Re+8H2O+2NH3

[0046] The above merely describes specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any modification, equivalent replacement, and improvement within the technical range disclosed by the present application and within the spirit and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method for extracting germanium and rhenium from coal conversion ash, characterized in that, Includes the following steps: S1. The coal conversion ash residue is separated by flotation to obtain residual carbon and tailings ash; the coal conversion ash residue is fly ash or coal gasification ash residue; S2. Grind and mix the tailings ash and additives evenly, and then perform thermal activation treatment; the additives are sodium hydroxide or calcium hydroxide; S3. The mixture after thermal activation treatment is cooled to room temperature, and then leached and filtered to obtain a germanium-rhenium leachate; S4. Separate germanium and rhenium in the leachate to obtain pre-purified germanium and a rhenium-rich solution; the specific operation is: (1) Extraction: Mix the leachate with ethyl acetate at a volume ratio of 1:1, stir to fully dissolve germanium and rhenium in ethyl acetate, let stand for 20-30 minutes to separate the organic phase and aqueous phase, and repeat the extraction step 3-5 times. (2) Evaporation: The extracted organic phase is rotary evaporated to 10-12% of the original solution volume to concentrate the germanium and rhenium solution; (3) Separation of germanium: Slowly add 1 mol / L hydrogen peroxide to the concentrated solution and stir continuously to oxidize the germanium ions into GeO2 precipitate; After the oxidation reaction is complete, let it stand for 1 to 2 hours, separate the precipitate, wash and dry it to obtain germanium precipitate; rhenium ions are oxidized to peroxyrhenic acid, and the solution obtained by separating the germanium precipitate is rhenium solution; S5. Purify the initially purified germanium and purify the rhenium solution to obtain high-purity germanium and rhenium. The specific operation is as follows: (1) Purification of germanium: Put the dried germanium precipitate into the reduction furnace, pass hydrogen gas through it, control the temperature at 700-900℃, and keep it for 2-4 hours to generate high-purity germanium product. (2) Purification of rhenium: Slowly add 30% ammonia water to the rhenium-containing solution, stir continuously at room temperature, and control the pH to 7-8. The white precipitate produced by the reaction is ammonium perrylate. Separate the precipitate, wash and dry it; put the dried rhenium precipitate into a reduction furnace, introduce hydrogen gas, control the temperature at 800-1000℃, and maintain it for 3-5 hours to generate high-purity rhenium product.

2. The method for extracting germanium and rhenium from coal conversion ash according to claim 1, characterized in that, In step S1, before the coal conversion ash slag is separated by flotation, grinding is performed: grinding is carried out for 10 to 40 minutes under the condition of grinding concentration of 25% to 45% to fully dissociate carbon and ash.

3. The method for extracting germanium and rhenium from coal conversion ash according to claim 1, characterized in that, In step S2, the mass ratio of tailings ash to additives is 1:0.8 to 1.8, the temperature of the thermal activation treatment is 500 to 700°C, the heating rate is 5 to 12°C / min, and the time is 1 to 4 hours.

4. The method for extracting germanium and rhenium from coal conversion ash according to claim 1, characterized in that, In step S3, the leaching conditions are as follows: deionized water is used as the leaching agent, and the mixture of deionized water and heat-activated treatment is leached at a liquid-solid ratio of (6-10):1L / kg, and stirred at 300-800r / min for 2-5 hours.

5. The method for extracting germanium and rhenium from coal conversion ash according to claim 1, characterized in that, In step S4 (1), the extraction stirring rate is 300-500 r / min.

6. The method for extracting germanium and rhenium from coal conversion ash according to claim 1, characterized in that, In step S4, operation (3), the temperature for drying the precipitate is 50-60°C and the time is 6 hours.

7. The method for extracting germanium and rhenium from coal conversion ash according to claim 1, characterized in that, In step S5, operation (2), the temperature for drying the precipitate is 80-100℃.

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