Use of guanidine functionalized microspheres in recovering gold (I) from thiosulfate solutions

Abstract

The application discloses application of guanidine functionalized microspheres to recovery of gold (I) in a thiosulfate solution and belongs to the technical field of precious metal recovery. In the application, a compound containing a guanidine functional group ((NH2)2C(=NH)) is used as a modifying reagent, chloromethylated polystyrene microspheres are used as a carrier, anhydrous sodium carbonate is used as an acid-binding agent, and dimethylformamide is used as a solvent, and an adsorbent containing the guanidine functional group is prepared through a nucleophilic substitution reaction. The guanidine functionalized microspheres prepared by the method can efficiently recover [Au(S2O3)2] 3‑ complex ions in a thiosulfate gold leaching solution and is not easy to be pulverized; the preparation of the adsorbent is simple and easy to implement and has low cost. In general, the material prepared in the application is an excellent adsorbent for recovery of gold (I) in a thiosulfate solution.

Description

Technical Field

[0001] This invention relates to the application of guanidine-functionalized microspheres in the recovery of gold (I) from thiosulfate solutions, belonging to the field of precious metal recovery technology. Background Technology

[0002] Gold, as a rare and precious metal, is not only a global currency but also an indispensable material for various high-tech industries. Gold mines, as the primary source of gold, commonly employ cyanide leaching in hydrometallurgy. However, cyanide is a highly toxic substance, posing serious harm to human health and the environment. Therefore, the research and development of non-cyanide gold extraction technologies are of profound significance. Thiosulfate leaching is considered one of the most promising green non-cyanide gold extraction technologies due to its advantages such as fast leaching speed, low reagent cost, non-toxicity, environmental friendliness, and ease of processing copper- and arsenic-containing carbonaceous gold ores. However, the thiosulfate leaching system is complex, and thiosulfates are prone to decomposition [Au(S₂O₃)₂]. 3- The high charge and large complex molecules mean that methods suitable for gold recovery in cyanide or other leaching systems are not necessarily applicable to thiosulfate systems. Therefore, a significant problem in the application of the thiosulfate gold extraction method is the difficulty in recovering gold from the leaching solution.

[0003] Currently, commonly used methods for recovering gold (I) from gold thiosulfate leaching solutions include displacement, adsorption, solvent extraction, and electrodeposition. Displacement is costly to use directly for recovering gold from gold thiosulfate leaching solutions, making it difficult to apply in actual production. Although solvent extraction has a high recovery rate, the economic cost is increased due to factors such as the need for solid-liquid separation of the slurry and the large consumption of extractant. Electrodeposition is suitable for separating gold when the gold concentration is high, but the gold content in actual gold thiosulfate leaching solutions is generally low, so it is not suitable for recovering gold from gold thiosulfate leaching solutions.

[0004] Adsorption methods are favored by researchers due to their simplicity, low cost, and suitability for recovering solutions with low metal ion concentrations. However, most adsorbents are currently only suitable for gold ions in cyanide or other leaching systems, as the properties of gold ions and [Au(S2O3)2]... 3- Since the properties are different, adsorbents cannot be used interchangeably. Therefore, it is of great significance to seek an economical, efficient and convenient adsorbent material for recovering gold(I) from thiosulfate leachate. Summary of the Invention

[0005] The technical problem this invention aims to solve is that most existing adsorbents can only adsorb gold ions and cannot adsorb [Au(S2O3)2]. 3- .

[0006] The purpose of this invention is to provide an application of guanidine-functionalized microspheres in the recovery of gold (I) from thiosulfate solutions. The guanidine-functionalized microspheres have the advantages of low cost, high efficiency, and ease of implementation.

[0007] The guanidine-functionalized microspheres of this invention are obtained by modifying chloromethylated polystyrene microspheres with compounds containing guanidine functional groups. The modified microspheres can efficiently adsorb gold (I) in thiosulfate solution.

[0008] Preferably, the compound containing the guanidine functional group is one of guanidine hydrochloride, aminoguanidine, 1,3-diaminoguanidine, 1-(o-tolyl)biguanidine, and morpholine guanidine hydrochloride.

[0009] Preferably, the mass ratio of chloromethylated polystyrene microspheres to compounds containing guanidine functional groups is 1:(0.5-3).

[0010] Preferably, the preparation method of the guanidine functionalized microspheres specifically includes the following steps:

[0011] (1) Chloromethylated polystyrene microspheres are mixed with compounds containing guanidine functional groups, nitrogen-nitrogen dimethylformamide, and anhydrous sodium carbonate.

[0012] (2) The mixture obtained in step (1) was refluxed under oil bath heating conditions. After the reaction was completed, it was washed repeatedly with water and ethanol until neutral, and then dried in a vacuum drying oven to obtain guanidine functionalized microspheres.

[0013] Preferably, in step (1), the molar ratio of the compound containing the guanidine functional group to anhydrous sodium carbonate is 1:0.7, and the solid-liquid ratio of chloromethylated polystyrene microspheres to N-dimethylformamide is 1g:30ml.

[0014] Preferably, in step (2), the oil bath temperature is 70-120℃ and the reflux time is 4-24h.

[0015] Preferably, the amount of guanidine-functionalized microspheres added to the thiosulfate solution is 1 g / L to 10 g / L.

[0016] The specific adsorption method is as follows: Guanidine functionalized microspheres are added to a gold (I)-containing thiosulfate solution and adsorption is carried out by mechanical stirring. The pH of the solution is adjusted to alkaline before the adsorbent is added.

[0017] This invention involves reacting chloromethylated polystyrene microspheres with a compound containing guanidine functional groups to synthesize a compound capable of adsorbing [Au(S2O3)2]. 3- The adsorbent, through experiments, revealed that unmodified p-chloromethylated polystyrene microspheres are effective against [Au(S2O3)2]. 3- It has no adsorption properties, so simply mixing the two together for adsorption will not be effective.

[0018] Beneficial effects of the present invention

[0019] (1) In this invention, guanidine-functionalized microspheres are used for the recovery of Au(I) from thiosulfate solution. The synthesized guanidine-functionalized microspheres have stable performance and can effectively recover gold from simulated and actual thiosulfate solutions.

[0020] (2) Guanidine functionalized microspheres can achieve rapid solid-liquid separation after adsorption of Au(I), and the guanidine functionalized microspheres loaded with Au(I) have good desorption performance.

[0021] (3) The method described in this invention has a simple modification process, low cost, and the synthesized adsorbent material has a good gold recovery effect. Detailed Implementation

[0022] The technical solution of the present invention will be further illustrated below through specific embodiments. However, the following embodiments are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0023] Example 1

[0024] This embodiment uses guanidine hydrochloride as a modifier to recover gold(I) from thiosulfate solution using guanidine-functionalized microspheres obtained through modification, including the following steps:

[0025] (1) Add 1g of chloromethylated polystyrene microspheres, 0.5g of guanidine hydrochloride, and 0.41g of anhydrous sodium carbonate to 30ml of nitrogen-nitrogen dimethylformamide and mix well.

[0026] (2) The mixture obtained in step (1) was refluxed for 24 hours under an oil bath heating condition at 80°C. After cooling, it was repeatedly washed with water and ethanol until neutral. It was then dried in a vacuum drying oven at 60°C to obtain guanidine functionalized microspheres.

[0027] (3) Take 0.2g of the guanidine-functionalized microspheres obtained in step (2) and add them to a volume of 100mL. The Au(I) concentration is 25mg / L, and the S2O3 concentration is 25mg / L. 2- The gold was adsorbed by stirring in a simulated gold thiosulfate leaching solution with a concentration of 0.1 mol / L. The solid-liquid ratio was 1:500, the adsorption time was 24 h, and the initial pH was 9.0.

[0028] The calculated loading of gold on guanidine-functionalized microspheres was 8.9 kg / t.

[0029] Example 2

[0030] This embodiment uses aminoguanidine hydrochloride as a modifier to obtain guanidine-functionalized microspheres for the recovery of gold (I) from thiosulfate solution, including the following steps:

[0031] (1) Add 1g of chloromethylated polystyrene microspheres, 3g of aminoguanidine hydrochloride, and 2.23g of anhydrous sodium carbonate to 30ml of nitrogen-nitrogen dimethylformamide and mix well.

[0032] (2) The mixture obtained in step (1) was refluxed for 24 hours under oil bath heating at 70°C. After cooling, it was repeatedly washed with water and ethanol until neutral. It was then dried in a vacuum drying oven at 60°C to obtain guanidine functionalized microspheres.

[0033] (3) Take 0.2g of the guanidine-functionalized microspheres obtained in step (2) and add them to a volume of 100mL. The Au(I) concentration is 25mg / L, and the S2O3 concentration is 25mg / L. 2- The gold was adsorbed by stirring in a simulated gold thiosulfate leaching solution with a concentration of 0.1 mol / L. The solid-liquid ratio was 1:500, the adsorption time was 24 h, and the initial pH was 9.0.

[0034] The calculated loading of gold on guanidine-functionalized microspheres was 10.13 kg / t.

[0035] Example 3

[0036] This embodiment uses 1,3-diaminoguanidine hydrochloride as a modifier to recover gold(I) from thiosulfate solution using the modified guanidine-functionalized microspheres, including the following steps:

[0037] (1) Add 1g of chloromethylated polystyrene microspheres, 1.14g of 1,3-diaminoguanidine hydrochloride, and 0.74g of anhydrous sodium carbonate to 30ml of nitrogen-nitrogen dimethylformamide, and mix well.

[0038] (2) The mixture obtained in step (1) was refluxed for 4 hours under oil bath heating at 120°C. After cooling, it was repeatedly washed with water and ethanol until neutral. It was then dried in a vacuum drying oven at 60°C to obtain guanidine functionalized microspheres.

[0039] (3) Take 0.2g of the guanidine-functionalized microspheres obtained in step (2) and add them to a volume of 100mL. The Au(I) concentration is 25mg / L, and the S2O3 concentration is 25mg / L. 2- The gold was adsorbed by stirring in a simulated gold thiosulfate leaching solution with a concentration of 0.1 mol / L. The solid-liquid ratio was 1:500, the adsorption time was 24 h, and the initial pH was 9.0.

[0040] The calculated loading of gold on guanidine-functionalized microspheres was 7.95 kg / t.

[0041] Example 4

[0042] This embodiment uses 1-(o-tolyl)biguanide as a modifier to recover gold(I) from thiosulfate solution using the modified guanidine-functionalized microspheres, including the following steps:

[0043] (1) Add 1g of chloromethylated polystyrene microspheres, 1.74g of 1-(o-tolyl)biguanide, and 0.74g of anhydrous sodium carbonate to 30ml of nitrogen-nitrogen dimethylformamide, and mix well.

[0044] (2) The mixture obtained in step (1) was refluxed for 24 hours under an oil bath heating condition at 80°C. After cooling, it was repeatedly washed with water and ethanol until neutral. It was then dried in a vacuum drying oven at 60°C to obtain guanidine functionalized microspheres.

[0045] (3) Take 0.2g of the guanidine-functionalized microspheres obtained in step (2) and add them to a volume of 100mL. The Au(I) concentration is 25mg / L, and the S2O3 concentration is 25mg / L. 2- The gold was adsorbed by stirring in a simulated gold thiosulfate leaching solution with a concentration of 0.1 mol / L. The solid-liquid ratio was 1:500, the adsorption time was 24 h, and the initial pH was 9.0.

[0046] The calculated loading of gold on guanidine-functionalized microspheres was 8.61 kg / t.

[0047] Example 5

[0048] This embodiment uses morpholine guanidine hydrochloride as a modifier to recover gold(I) from thiosulfate solution using the modified guanidine-functionalized microspheres, including the following steps:

[0049] (1) Add 1g of chloromethylated polystyrene microspheres, 1.8784g of morpholine guanidine hydrochloride, and 0.74g of anhydrous sodium carbonate to 30ml of nitrogen-nitrogen dimethylformamide and mix well.

[0050] (2) The mixture obtained in step (1) was refluxed for 24 hours under an oil bath heating condition at 80°C. After cooling, it was repeatedly washed with water and ethanol until neutral. It was then dried in a vacuum drying oven at 60°C to obtain guanidine functionalized microspheres.

[0051] (3) Take 0.2g of the guanidine-functionalized microspheres obtained in step (2) and add them to a volume of 100mL. The Au(I) concentration is 25mg / L, and the S2O3 concentration is 25mg / L. 2- The gold was adsorbed by stirring in a simulated gold thiosulfate leaching solution with a concentration of 0.1 mol / L. The solid-liquid ratio was 1:500, the adsorption time was 24 h, and the initial pH was 9.0.

[0052] The calculated loading of gold on guanidine-functionalized microspheres was 10.42 kg / t.

[0053] Example 6

[0054] This embodiment uses aminoguanidine hydrochloride as a modifier to recover gold(I) from thiosulfate solution using the modified guanidine-functionalized microspheres, including the following steps:

[0055] (1) Add 1g of chloromethylated polystyrene microspheres, 1g of aminoguanidine hydrochloride, and 0.74g of anhydrous sodium carbonate to 30ml of nitrogen-nitrogen dimethylformamide and mix well.

[0056] (2) The mixture obtained in step (1) was refluxed for 24 hours under an oil bath heating condition at 80°C. After cooling, it was repeatedly washed with water and ethanol until neutral. It was then dried in a vacuum drying oven at 60°C to obtain guanidine functionalized microspheres.

[0057] (3) Adsorption of gold(I) in actual gold ore leaching solution by the material: Taking a high-sulfur, high-arsenic gold ore leaching solution containing approximately 20.4 g / t of gold after roasting as an example, the concentration of gold(I) in the leaching solution is 7.02 mg / L, Cu 2+ With a concentration of 5 mmol / L, an ethylenediamine (en) concentration of 10 mmol / L, and a pH of 9, 100 mL of the leachate was taken, and 1 g of the material obtained in step (2) was added. The mixture was mechanically stirred for 24 h for adsorption. After the adsorption experiment, the sample was subjected to oxidation, drying, and volume adjustment, and the gold concentration of the sample was finally analyzed. After 24 h, the gold in the actual leachate was basically completely adsorbed.

[0058] Example 7

[0059] This embodiment uses aminoguanidine hydrochloride as a modifier to recover gold(I) from thiosulfate solution using the modified guanidine-functionalized microspheres, including the following steps:

[0060] (1) Add 1g of chloromethylated polystyrene microspheres, 1g of aminoguanidine hydrochloride, and 0.74g of anhydrous sodium carbonate to 30ml of nitrogen-nitrogen dimethylformamide and mix well.

[0061] (2) The mixture obtained in step (1) was refluxed for 24 hours under oil bath heating at 100°C. After cooling, it was repeatedly washed with water and ethanol until neutral. It was then dried in a vacuum drying oven at 60°C to obtain guanidine functionalized microspheres.

[0062] (3) Adsorption of gold(I) in actual gold ore leaching solution by the material: Taking a high-sulfur, high-arsenic gold ore leaching solution with a gold content of approximately 20.4 g / t as an example, the concentration of gold(I) in the leaching solution is 6.71 mg / L, Cu 2+ Concentration of 5 mmol / L, NH3 / NH4 + With a concentration of 2 mol / L and a pH of 9, 100 mL of the leachate was taken, and 1 g of the material obtained in step (2) was added. The mixture was mechanically stirred and adsorbed for 24 h. After the adsorption experiment, samples were taken and subjected to oxidation, drying, and volume adjustment. Finally, the gold concentration of the sample was analyzed. After 24 h, the adsorption rate of the material on the gold in the actual leachate was greater than 83%.

Claims

1. An application of guanidine-functionalized microspheres in the recovery of gold (I) from thiosulfate solution, characterized in that: The guanidine-functionalized microspheres were obtained by modifying chloromethylated polystyrene microspheres with compounds containing guanidine functional groups. The compound containing the guanidine functional group is one of guanidine hydrochloride, aminoguanidine, 1,3-diaminoguanidine, 1-(o-tolyl)biguanidine, and morpholine guanidine hydrochloride. The mass ratio of chloromethylated polystyrene microspheres to compounds containing guanidine functional groups is 1:(0.5~3); The preparation method of the guanidine functionalized microspheres specifically includes the following steps: (1) Mix chloromethylated polystyrene microspheres with a compound containing guanidine functional groups, N-dimethylformamide, and anhydrous sodium carbonate; (2) The mixture obtained in step (1) was refluxed under oil bath heating conditions. After the reaction was completed, it was repeatedly washed with water and ethanol until neutral, and then dried in a vacuum drying oven to obtain guanidine functionalized microspheres. Step (1) The molar ratio of the compound containing the guanidine functional group to anhydrous sodium carbonate is 1:0.7, and the solid-liquid ratio of chloromethylated polystyrene microspheres to N-dimethylformamide is 1g:30ml.

2. The application according to claim 1, characterized in that: In step (2), the oil bath temperature is 70-120℃ and the reflux time is 4-24h.

3. The application according to claim 1, characterized in that: The amount of guanidine-functionalized microspheres added to the thiosulfate solution is 1 g / L to 10 g / L.