Preparation method of precipitant for SED-MET germanium deposition method

Abstract

The invention discloses a preparation method of a precipitator for an SED-MET germanium precipitation method, and belongs to the technical field of hydrometallurgy. The preparation method comprises the following steps: adding 5 to 10g of 3-mercaptosalicylic acid and 20 to 40mL of absolute ethyl alcohol into a reaction container, adding 1 to 5mL of concentrated sulfuric acid, and reacting at 80 to 100 DEG C for 10 to 30 minutes to generate ethyl 3-mercaptosalicylate. And after the reaction is finished, adjusting the pH value of the reaction system to be neutral, extracting the ethyl 3-mercaptosalicylate, removing water, filtering, separating the extracting agent, and purifying the product to obtain the target precipitating agent. According to the preparation method, the material ratio, the catalyst dosage, the reaction temperature and the reaction time are optimized, side reactions are effectively prevented, the product yield is increased, and a mixed solvent system is selected for recrystallization, so that a high-purity product can be obtained. The preparation method has the advantages of easily available raw materials, simple production process and good process compatibility, has the advantages of environmental protection and cost, and is suitable for the industrialization demand of the SED-MET germanium deposition method.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrometallurgy, and particularly relates to a preparation method of a precipitant for SED-MET germanium precipitation method. Background Art

[0002] To achieve efficient recovery of germanium by using the SED-MET germanium precipitation method, high selectivity, high recovery rate and economic feasibility need to be considered. Currently, the commonly used precipitants mainly include the following several kinds: tannic acid-based precipitants such as sulfonated tannin, etc., have poor selectivity, are prone to coprecipitation with Fe 3+ , Si 4+ etc., and the precipitation is difficult to filter, increasing the complexity of the process; metal sulfide-based precipitants such as hydrogen sulfide, sodium sulfide, etc., not only have poor selectivity, will coprecipitate heavy metals such as Cu, As, Cd, etc., but also due to their high toxicity, have high requirements for the operating environment and equipment; while organic acid-based precipitants such as oxalic acid and citric acid, etc., need to strictly control the pH value of the reaction system, and the precipitation is incomplete when the germanium concentration is low, resulting in low recovery rate. Based on this, the present invention aims to provide a preparation method of a precipitant for SED-MET germanium precipitation method that is safe and efficient, has a simple process, and is environmentally friendly, improves the purity of germanium recovery, and realizes the efficient recovery and utilization of germanium resources. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method of a precipitant for SED-MET germanium precipitation method.

[0004] The purpose of the present invention is achieved as follows: The preparation method of the precipitant for SED-MET germanium precipitation method includes the following steps: Add 5 - 10 g of 3-mercapto salicylic acid and 20 - 40 mL of absolute ethanol into a reaction vessel, add 1 - 5 mL of concentrated sulfuric acid, and react at 80 - 100 °C for 10 - 30 min to generate ethyl 3-mercapto salicylate; After the reaction is completed, adjust the pH value of the reaction system to neutral, extract ethyl 3-mercapto salicylate, remove water, filter, separate the extractant, and purify the product to obtain the target precipitant.

[0005] Compared with the prior art, the technical solution of the present invention has the following advantages: For the precipitant prepared by using the technical solution of the present invention, the hydroxyl group (-OH) and carboxyl group (-COOH) in its ligand can provide oxygen atoms to form coordination bonds with germanium ions (Ge 4+ ), and at the same time, the mercapto group (-SH) provides sulfur atoms to further enhance the coordination ability. The ligand and germanium ions form stable insoluble precipitates through multiple coordination effects. This structure not only improves the stability of the precipitate but also significantly enhances the selective precipitation ability for germanium ions.

[0006] The technical solution of the present invention optimizes the catalyst dosage, avoids incomplete oxidation of mercapto groups or esterification reactions, and improves the product yield. By optimizing the material ratio of 3-mercapto salicylic acid to absolute ethanol, the reaction temperature and time, the formation of carboxyl dimers is inhibited, effectively preventing side reactions. The entire reaction process is supplemented with inert gas protection to further avoid mercapto oxidation. Recrystallization is carried out using a mixed solvent system to separate unreacted residues, and a high-purity product can be obtained, which meets the industrialization requirements of the SED-MET germanium precipitation method.

[0007] In addition, the raw materials of the technical solution of the present invention are easily available, the production process is simple, the process compatibility is good, the product ethyl 3-mercapto salicylate is safer to operate than traditional precipitants, and the decomposition products are environmentally friendly, having both environmental protection and cost advantages, and having great promotion and application value. Specific Embodiments

[0008] The present invention will be further described below, but it is not limited to the present invention in any way. Any transformation or substitution based on the teachings of the present invention belongs to the protection scope of the present invention.

[0009] The preparation method of the precipitant for the SED-MET germanium precipitation method includes the following steps: Add 5-10 g of 3-mercapto salicylic acid and 20-40 mL of absolute ethanol to the reaction vessel, add 1-5 mL of concentrated sulfuric acid, and react at 80-100 °C for 10-30 min to produce ethyl 3-mercapto salicylate; After the reaction is completed, adjust the pH value of the reaction system to neutral, extract ethyl 3-mercapto salicylate, remove water, filter, separate the extractant, and purify the product to obtain the target precipitant.

[0010] The temperature of the reaction is preferably 80-90 °C.

[0011] The time of the reaction is preferably 15-25 min.

[0012] When the reaction is carried out, an inert gas is introduced at a flow rate of 10-20 mL / min for protection to reduce mercapto oxidation. It is preferred to introduce the inert gas before the reaction starts to displace the air in the reaction system. The inert gas is any one of nitrogen or argon.

[0013] The concentrated sulfuric acid is sulfuric acid with a concentration ≥ 95%.

[0014] The pH value of the reaction system is adjusted using a 0.1-0.5 mol / L sodium carbonate solution.

[0015] The extraction of ethyl 3-mercapto salicylate refers to extraction with ethyl acetate and then separation of the organic phase.

[0016] The water removal refers to drying the separated organic phase with anhydrous sodium sulfate after extracting ethyl 3-mercaptobenzoate.

[0017] The separation of the extractant refers to separating the extractant by means of vacuum distillation.

[0018] The purification of the product refers to recrystallization purification using a mixed solvent system of ethanol and water, a mixed solvent system of ethyl acetate and n-hexane, or a mixed solvent system of dichloromethane and petroleum ether.

[0019] When the mixed solvent system is composed of ethanol and water, the volume ratio is 7:3 or 8:2; when composed of ethyl acetate and n-hexane, the volume ratio is 1:2; when composed of dichloromethane and petroleum ether, the volume ratio is 1:3.

[0020] Example 1

[0021] Add 5 g of 3-mercaptobenzoic acid and 20 mL of anhydrous ethanol to a reaction vessel, add 1 mL of concentrated sulfuric acid, introduce nitrogen for protection at a flow rate of 10 mL / min, and react at 80 °C for 30 min to produce ethyl 3-mercaptobenzoate. After the reaction is completed, adjust the pH value of the reaction system to neutral with 0.2 mol / L sodium carbonate solution, extract ethyl 3-mercaptobenzoate with ethyl acetate, separate the organic phase, dry the separated organic phase with anhydrous sodium sulfate, and after filtration, separate the extractant by vacuum distillation. Recrystallize and purify the product with a mixed solvent of ethanol and water (volume ratio 7:3) to obtain the target precipitant.

[0022] Example 2

[0023] Add 6 g of 3-mercaptobenzoic acid and 25 mL of anhydrous ethanol to a reaction vessel, add 2 mL of concentrated sulfuric acid, introduce argon for protection at a flow rate of 15 mL / min, and react at 85 °C for 25 min to produce ethyl 3-mercaptobenzoate. After the reaction is completed, adjust the pH value of the reaction system to neutral with 0.5 mol / L sodium carbonate solution, extract ethyl 3-mercaptobenzoate with ethyl acetate, separate the organic phase, dry the separated organic phase with anhydrous sodium sulfate, and after filtration, separate the extractant by vacuum distillation. Recrystallize and purify the product with a mixed solvent of ethanol and water (volume ratio 8:2) to obtain the target precipitant.

[0024] Example 3

[0025] Add 10 g of 3-mercapto salicylic acid and 40 mL of absolute ethanol to a reaction vessel, add 5 mL of concentrated sulfuric acid, introduce nitrogen for protection at a flow rate of 20 mL / min, and react at 90 °C for 15 min to produce ethyl 3-mercapto salicylate. After the reaction is completed, adjust the pH value of the reaction system to neutral with 0.3 mol / L sodium carbonate solution, extract ethyl 3-mercapto salicylate with ethyl acetate, separate the organic phase, dry the separated organic phase with anhydrous sodium sulfate, filter, and then distill under reduced pressure to separate the extractant. Recrystallize and purify the product with a mixed solvent of dichloromethane and petroleum ether (volume ratio 1:3) to obtain the target precipitating agent.

[0026] Example 4

[0027] Add 8 g of 3-mercapto salicylic acid and 30 mL of absolute ethanol to a reaction vessel, add 4 mL of concentrated sulfuric acid, introduce argon for protection at a flow rate of 15 mL / min, and react at 100 °C for 10 min to produce ethyl 3-mercapto salicylate. After the reaction is completed, adjust the pH value of the reaction system to neutral with 0.1 mol / L sodium carbonate solution, extract ethyl 3-mercapto salicylate with ethyl acetate, separate the organic phase, dry the separated organic phase with anhydrous sodium sulfate, filter, and then distill under reduced pressure to separate the extractant. Recrystallize and purify the product with a mixed solvent of ethyl acetate and n-hexane (volume ratio 1:2) to obtain the target precipitating agent.

Claims

1. A method for preparing a precipitant for SED-MET germanium precipitation method, characterized in that: The steps include: Add 5-10 g of 3-mercaptosalicylic acid and 20-40 mL of anhydrous ethanol into a reaction vessel, add 1-5 mL of concentrated sulfuric acid, and react at 80-100°C for 10-30 min to generate ethyl 3-mercaptosalicylate; After the reaction is completed, the pH value of the reaction system is adjusted to neutral, 3-mercaptosalicylic acid ethyl ester is extracted, water is removed, the extractant is filtered, and the product is purified to obtain the target precipitant.

2. The method for preparing a precipitant according to claim 1, characterized in that: The reaction temperature is 80-90°C.

3. The method for preparing a precipitant according to claim 1, characterized in that: The reaction time is 15 to 25 minutes.

4. The method for preparing a precipitant according to claim 1, characterized in that: During the reaction, an inert gas protection is introduced at a flow rate of 10-20 mL / min.

5. The method for preparing a precipitant according to claim 1, characterized in that: The pH value of the reaction system is adjusted using a 0.1-0.5 mol / L sodium carbonate solution.

6. The method for preparing a precipitant according to claim 1, characterized in that: The extracting of ethyl 3-mercaptosalicylate refers to extracting with ethyl acetate and then separating the organic phase.

7. The method for preparing a precipitant according to claim 1, characterized in that: The dehydration refers to extracting ethyl 3-mercaptosalicylate and then drying the separated organic phase with anhydrous sodium sulfate.

8. The method for preparing a precipitant according to claim 1, characterized in that: The separation of the extractant refers to separation of the extractant by a reduced pressure distillation method.

9. The method for preparing a precipitant according to claim 1, characterized in that: The purified product refers to a product that is purified by recrystallization using a mixed solvent system of ethanol and water, a mixed solvent system of ethyl acetate and n-hexane, or a mixed solvent system of dichloromethane and petroleum ether.