Method for regenerating failed gold extraction agent

Abstract

The invention relates to a method for regenerating an invalid gold extraction agent. The method comprises the following steps: (1) sodium sulfite pretreatment; (2) reducing the extracting agent: firstly adding sodium hydroxide into the gold extracting agent pretreated in the step (1) to adjust the pH value, then adding a hydrazine hydrate reducing agent, reacting for 1-1.5 hours, and filtering to obtain the reduced gold extracting agent; and (3) hydrogen is supplemented through hydrochloric acid, and finally the regenerated gold extraction agent is obtained. Through the process route of sodium sulfite pretreatment, extraction agent reduction and hydrochloric acid hydrogen supplementation, impurities in the invalid gold extraction agent can be effectively removed, and the extraction capacity of the invalid gold extraction agent is recovered. After the regenerated gold extraction agent and the new gold extraction agent are mixed according to the ratio of 1: 1, the extraction rate of gold in the gold-containing solution reaches 99% or above, the service life of the extraction agent is remarkably prolonged, the production cost is reduced, the use amount of the new extraction agent and the output of the waste extraction agent are reduced, and the environmental risk caused by treatment of the waste extraction agent is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of extractant regeneration, and in particular to a method for regenerating a spent gold extractant. Background Art

[0002] In the precious metal refining and purification process, dibutyl carbitol is usually used as a gold extractant to separate gold from other precious metals. Dibutyl carbitol extractant can form a stable complex with gold ions in the precious metal refining solution, thereby realizing efficient gold extraction; then, oxalic acid is used as a stripping agent to displace the gold element from the gold-carrying extractant, and a gold powder product is obtained after a series of washing and drying. Dibutyl carbitol extractant is a recyclable reagent, but because the precious metal refining solution contains impurity elements such as sulfur that can be co-extracted by dibutyl carbitol, and these co-extracted impurities have no open circuit during the extraction process, they will gradually accumulate in the extractant. Over time, these accumulated impurities will seriously affect the selectivity and extraction rate of the extractant, resulting in a decrease in the gold extraction rate until the extractant is completely ineffective. To address this problem, the current solution is usually to destructively treat the ineffective dibutyl carbitol extractant. Once the performance of the extractant is reduced to the point where it cannot meet the production requirements, it must be stopped from use, and it must be completely decomposed or harmlessly treated by chemical or physical methods, and then replaced with a new extractant to maintain the normal operation of the production line. This not only increases production costs, but may also cause environmental pollution if the waste extractant is not handled properly. Summary of the invention

[0003] In view of the problem in the prior art that the dibutyl carbitol extractant can only be treated destructively after it becomes ineffective, the present invention provides a method for regenerating an ineffective gold extractant, which can achieve the regeneration of ineffective dibutyl carbitol. After the regeneration, the performance of the extractant is restored and can be recycled.

[0004] To achieve the above object, the technical solution of the present invention is as follows:

[0005] A method for regenerating an exhausted gold extractant comprises the following steps:

[0006] (1) Sodium sulfite pretreatment: Sodium sulfite solution and spent gold extractant are mixed in a volume ratio of 2-3:1, reacted for 40-60 minutes, and phase separated to obtain a pretreated gold extractant;

[0007] (2) Extraction agent reduction: first, sodium hydroxide is added to the gold extraction agent after the pretreatment described in step (1) to adjust the pH value, and then hydrazine hydrate is added as a reducing agent, reacted for 1-1.5 hours, and filtered to obtain a reduced gold extraction agent;

[0008] (3) Hydrogenation with hydrochloric acid: The reduced gold extractant in step (2) is mixed with hydrochloric acid in a volume ratio of 1:1-2, and reacted for 30-40 minutes to obtain a regenerated gold extractant.

[0009] Furthermore, the spent gold extractant includes dibutyl carbitol.

[0010] Furthermore, the concentration of the sodium sulfite solution in step (1) is 15-20%.

[0011] Furthermore, in step (2), the pH value is adjusted to 8-9.

[0012] Furthermore, the preparation method of the hydrazine hydrate reducing agent described in step (2) comprises the following steps: mixing hydrazine hydrate and ethanol in a volume ratio of 5-6:1, and stirring for 30-40 minutes.

[0013] Furthermore, the amount of the hydrated hydrazine reducing agent added in step (2) is 30-35% of the volume of the pretreated gold extractant.

[0014] Furthermore, the concentration of the hydrochloric acid solution in step (3) is 3-4 mol / L.

[0015] The reaction mechanism involved in the present invention is as follows:

[0016] First, sodium sulfite is used as a reducing agent to pretreat the spent extractant to remove impurity elements such as sulfur in the extractant. Then, the sodium ions in sodium hydroxide are used to exchange other metal ions in the extractant. Hydrazine hydrate is used as a reducing agent to reduce the exchanged other metal ions to metals, which are then removed by filtration. Finally, hydrochloric acid is used to exchange the sodium ions in the extractant to achieve regeneration of the extractant.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention provides a method for regenerating an expired gold extractant. Through the process of sodium sulfite pretreatment, extractant reduction, and hydrochloric acid hydrogenation, impurities in the expired gold extractant can be effectively removed and its extraction capacity can be restored. After the regenerated gold extractant is mixed with the new gold extractant in a ratio of 1:1, the extraction rate of gold in the gold-containing solution reaches more than 99%, which significantly extends the service life of the extractant, reduces production costs, reduces the use of new extractants and the generation of waste extractants, and avoids the environmental risks caused by the treatment of waste extractants. The regeneration method has clear steps and is easy to operate. It does not require complex equipment and cumbersome operating procedures. It has a low technical threshold and can be widely used. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The embodiments of the present invention are further described below with reference to the accompanying drawings, in which:

[0020] Figure 1 A process flow chart for regeneration of spent gold extractant is shown. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] Example 1

[0023] A method for regenerating an exhausted gold extractant comprises the following steps:

[0024] (1) Sodium sulfite pretreatment: a 20% sodium sulfite solution was mixed with a spent gold extractant in a volume ratio of 2:1, reacted for 60 minutes, and phase-separated to obtain a pretreated gold extractant;

[0025] (2) Extraction agent reduction: first, sodium hydroxide is added to the pretreated gold extractant obtained in step (1) to adjust the pH value to 8, and then a hydrazine hydrate reducing agent is added, reacted for 1 hour, and filtered to obtain a reduced gold extractant; the hydrazine hydrate reducing agent is obtained by mixing hydrazine hydrate and ethanol in a volume ratio of 5:1 and stirring for 30 minutes, and the amount of the hydrazine hydrate reducing agent added is 30% of the volume of the pretreated gold extractant;

[0026] (3) Hydrogenation with hydrochloric acid: The reduced gold extractant obtained in step (2) was mixed with 4 mol / L hydrochloric acid in a volume ratio of 1:1 and reacted for 30 min to obtain a regenerated gold extractant.

[0027] The regenerated gold extractant obtained in this embodiment was mixed with the new gold extractant in a volume ratio of 1:1, and a gold-containing solution with the same volume as the mixed gold extractant was added for extraction for 1 hour, and the phases were separated to obtain a raffinate and a loaded extractant; after testing, the gold content in the gold-containing solution was 1.47 g / L, the gold content in the raffinate was 0.0089 g / L, and the gold extraction rate was 99.39%, indicating that the performance of the regenerated gold extractant was restored and could be recycled.

[0028] Example 2

[0029] A method for regenerating an exhausted gold extractant comprises the following steps:

[0030] (1) Sodium sulfite pretreatment: a sodium sulfite solution having a concentration of 15% was mixed with a spent gold extractant in a volume ratio of 3:1, reacted for 40 minutes, and phase-separated to obtain a pretreated gold extractant;

[0031] (2) Extraction agent reduction: first, sodium hydroxide is added to the pretreated gold extractant obtained in step (1) to adjust the pH value to 9, and then a hydrazine hydrate reducing agent is added, reacted for 1.5 hours, and filtered to obtain a reduced gold extractant; the hydrazine hydrate reducing agent is obtained by mixing hydrazine hydrate and ethanol in a volume ratio of 6:1 and stirring for 40 minutes, and the amount of the hydrazine hydrate reducing agent added is 35% of the volume of the pretreated gold extractant;

[0032] (3) Hydrogenation with hydrochloric acid: The reduced gold extractant obtained in step (2) was mixed with 3 mol / L hydrochloric acid in a volume ratio of 1:2 and reacted for 40 min to obtain a regenerated gold extractant.

[0033] The regenerated gold extractant obtained in this embodiment was mixed with the new gold extractant in a volume ratio of 1:1, and a gold-containing solution with the same volume as the mixed gold extractant was added for extraction for 1 hour, and the phases were separated to obtain a raffinate and a loaded extractant; after testing, the gold content in the gold-containing solution was 1.12 g / L, the gold content in the raffinate was 0.0097 g / L, and the gold extraction rate was 99.13%, indicating that the performance of the regenerated gold extractant was restored and could be recycled.

[0034] The present invention provides a method for regenerating an expired gold extractant. Through the process of sodium sulfite pretreatment, extractant reduction, and hydrochloric acid hydrogenation, impurities in the expired gold extractant can be effectively removed and its extraction capacity can be restored. After the regenerated gold extractant is mixed with the new gold extractant in a ratio of 1:1, the extraction rate of gold in the gold-containing solution reaches more than 99%, which significantly extends the service life of the extractant, reduces production costs, reduces the use of new extractants and the generation of waste extractants, and avoids the environmental risks caused by the treatment of waste extractants. The regeneration method has clear steps and is easy to operate. It does not require complex equipment and cumbersome operating procedures. It has a low technical threshold and can be widely used.

[0035] Some exemplary embodiments of the present invention are described above. It can be understood that the above embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention. The features in these embodiments can be recombined in a suitable manner, and the scheme obtained thereby is still within the protection scope required by the present invention. Based on the above embodiments, all other embodiments obtained by those skilled in the art without making creative work, that is, all modifications, equivalent substitutions and improvements made within the spirit and principles of this application, fall within the protection scope required by the present invention.

Claims

1. A method for regenerating an exhausted gold extractant, characterized in that: The steps include: (1) Sodium sulfite pretreatment: Sodium sulfite solution and spent gold extractant are mixed in a volume ratio of 2-3:1, reacted for 40-60 minutes, and phase separated to obtain a pretreated gold extractant; (2) Extraction agent reduction: first, sodium hydroxide is added to the gold extraction agent after the pretreatment described in step (1) to adjust the pH value, and then hydrazine hydrate is added as a reducing agent, reacted for 1-1.5 hours, and filtered to obtain a reduced gold extraction agent; (3) Hydrogenation with hydrochloric acid: The reduced gold extractant in step (2) is mixed with hydrochloric acid in a volume ratio of 1:1-2, and reacted for 30-40 minutes to obtain a regenerated gold extractant.

2. The method for regenerating a spent gold extractant according to claim 1, characterized in that: The spent gold extractant includes dibutyl carbitol.

3. The method for regenerating a spent gold extractant according to claim 1, characterized in that: The concentration of the sodium sulfite solution in step (1) is 15-20%.

4. The method for regenerating a spent gold extractant according to claim 1, characterized in that: In step (2), the pH value is adjusted to 8-9.

5. The method for regenerating a spent gold extractant according to claim 1, characterized in that: The preparation method of the hydrazine hydrate reducing agent described in step (2) comprises the following steps: mixing hydrazine hydrate and ethanol in a volume ratio of 5-6:1, and stirring for 30-40 minutes.

6. The method for regenerating a spent gold extractant according to claim 1 or 5, characterized in that: The amount of the hydrated hydrazine reducing agent added in step (2) is 30-35% of the volume of the pretreated gold extractant.

7. The method for regenerating a spent gold extractant according to claim 1, characterized in that: The concentration of the hydrochloric acid solution in step (3) is 3-4 mol / L.

Images