Gold extraction agent and preparation method and application thereof

Abstract

The present application relates to a kind of gold extractant and its preparation method, application, the gold extractant is the aqueous solution containing inorganic copper salt, thiosulfate and EDDHA-Na, wherein, the molar concentration of Cu in the gold extractant is 0.005M-0.05M, S2O3 2+ Molar concentration is 0.005M-0.05M, S2O3 2‑ Molar concentration is 0.1M-1M;EDDHA-Na and water volume ratio is 1-20%.EDDHA-Na is mainly complexed with copper ion to form EDDHA-Cu complex ion, reduce the formation of copper-ammonia complex ion, thereby reducing the oxidation of thiosulfate ion, while EDDHA-Cu complex ion has catalytic effect on the dissolution of gold in thiosulfate ion solution, improve the leaching efficiency of gold.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal extraction, in particular to a gold extraction agent and a preparation method and application thereof. BACKGROUND

[0002] With increasing human concern for the ecological environment, the traditional cyanide method, which is a production gold process with strong toxicity, is banned in many countries and regions, and tailings containing cyanide are listed as hazardous waste.

[0003] The aqua regia dissolution method is to dissolve gold with a mixture of high-concentration nitric acid and high-concentration hydrochloric acid in a volume ratio of 1:3. Neither the concentrated nitric acid nor the high-concentration hydrochloric acid alone can react with gold. Meanwhile, the mixture produces highly toxic chlorine gas during use, and its strong corrosiveness requires the production equipment to be resistant to strong corrosion and oxidation, increasing equipment costs. The thiourea method can extract gold under both acidic and alkaline conditions, but it is more stable under acidic conditions and its technology is more mature. However, in recent years, it has been considered a carcinogen, greatly limiting its industrial application. The halogen method for extracting gold is a gold extraction method using halogen elements or their oxygen-containing acids as extractants. However, the large consumption of reagents, high price, and high requirements for equipment limit its application in industry.

[0004] Thiosulfate has the advantages of fast leaching rate, low toxicity, environmental protection, low price, and insensitivity to impurities, and has become the most potential non-cyanide gold leaching system. The commonly used thiosulfate gold leaching system is copper sulfate-ammonia-thiosulfate, in which ammonia stabilizes copper ions in the solution by forming a complex with Cu(II). Copper-ammonia complex ions act as catalysts to oxidize gold ions to gold ions and react with thiosulfate ions (S2O3 2- ) to form Au(S2O3)2 3- complex. However, copper-ammonia complex ions can also oxidize and decompose metastable S2O3 2- to generate polysulfate (S x O6 2- ), polysulfide (S x 2 ), and elemental sulfur, etc., increasing the consumption of thiosulfate. These substances can adhere to the surface of gold to form a passivation layer, reducing the leaching rate and leaching rate of gold. SUMMARY

[0005] The application provides a gold extraction agent and a preparation method and application thereof, and the gold extraction agent is prepared by mixing a divalent copper ion solution, a thiosulfate solution and EDDHA-Na, the EDDHA-Na is mainly combined with copper ions to form EDDHA-Cu complex ions, the formation of copper-ammonia complex ions is reduced, and the oxidation of thiosulfate ions is reduced, and the EDDHA-Cu complex ions have a catalytic effect on the dissolution of gold in the thiosulfate ion solution.

[0006] The application solves the above technical problems in the following manner: the gold extraction agent is an aqueous solution containing inorganic copper salt, thiosulfate and EDDHA-Na (sodium ethylenediamine di-o-phenylacetate), wherein, in the gold extraction agent, Cu 2+ The molar concentration of the inorganic copper salt is 0.005M-0.05M, the molar concentration of the thiosulfate is 0.01M-0.05M, and the molar concentration of the EDDHA-Na is 0.1M-1M. 2- The molar concentration of the inorganic copper salt is 0.005M-0.05M, the molar concentration of the thiosulfate is 0.01M-0.05M, and the molar concentration of the EDDHA-Na is 0.1M-1M.

[0007] The molar concentration of the inorganic copper salt is 0.005M-0.05M, the molar concentration of the thiosulfate is 0.01M-0.05M, and the molar concentration of the EDDHA-Na is 0.1M-1M. 2+ The molar concentration of the inorganic copper salt is 0.005M-0.05M, the molar concentration of the thiosulfate is 0.01M-0.05M, and the molar concentration of the EDDHA-Na is 0.1M-1M. 2- The molar concentration of the inorganic copper salt is 0.005M-0.05M, the molar concentration of the thiosulfate is 0.01M-0.05M, and the molar concentration of the EDDHA-Na is 0.1M-1M.

[0008] The molar concentration of the inorganic copper salt is 0.005M-0.05M, the molar concentration of the thiosulfate is 0.01M-0.05M, and the molar concentration of the EDDHA-Na is 0.1M-1M. 2+ The molar concentration of the inorganic copper salt is 0.005M-0.05M, the molar concentration of the thiosulfate is 0.01M-0.05M, and the molar concentration of the EDDHA-Na is 0.1M-1M. 2- The molar concentration of the inorganic copper salt is 0.005M-0.05M, the molar concentration of the thiosulfate is 0.01M-0.05M, and the molar concentration of the EDDHA-Na is 0.1M-1M.

[0009] Preferably, the inorganic copper salt is one of copper sulfate pentahydrate, copper nitrate, copper chloride and copper carbonate, and further preferably, the inorganic copper salt is copper sulfate pentahydrate.

[0010] Preferably, the thiosulfate is one of sodium thiosulfate and ammonium thiosulfate, and further preferably, the thiosulfate is ammonium thiosulfate.

[0011] The preparation method of the gold extraction agent is characterized in that the raw materials are weighed according to the ratio, the inorganic copper salt, the thiosulfate and the EDDHA-Na are mixed in a reaction container, water is added, and the mixture is stirred uniformly to obtain the gold extraction agent.

[0012] The application of the gold extraction agent in the extraction of gold in minerals is characterized in that the gold extraction agent is added to the minerals, ammonia water is added to adjust the pH of the solution, the solution is continuously stirred and leached, and then filtered to obtain a gold-containing leaching solution.

[0013] Preferably, the solid-liquid ratio of the minerals to the gold extraction agent is 1:3g-12mL, and further preferably, the solid-liquid ratio is 1g:9mL.

[0014] Preferably, the ammonia water adjusts the solution pH to 8-11, further preferably pH=10.

[0015] Preferably, the stirring leaching time is 1-108h; further 1-48h. The stirring speed is 200-2000r / min; further preferably 400-600r / min.

[0016] The beneficial effects of the present application are as follows:

[0017] 1. The present application adopts divalent copper ion solution, thiosulfate solution, EDDHA-Na mixed preparation gold extract solution, EDDHA-Na mainly complex with copper ion to form EDDHA-Cu complex ion, reduces the formation of copper-ammonia complex ion, thereby reducing the oxidation of thiosulfate ion by copper-ammonia complex ion, reducing the consumption of thiosulfate; at the same time, EDDHA-Cu complex ion has catalytic effect on the dissolution of gold in thiosulfate ion solution, improving the leaching rate and leaching rate of gold.

[0018] 2. The raw materials used in the present application are all environmentally friendly drugs, which are more environmentally friendly than traditional cyanide-containing drugs.

[0019] The above description is only a summary of the technical solutions of the present application, in order to more clearly understand the technical means of the present application, and the content of the specification can be implemented, the following preferred embodiments of the present application are described in detail with the help of the drawings. The specific embodiments of the present application are described in detail by the following examples and their drawings. BRIEF DESCRIPTION OF DRAWINGS

[0020] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute undue limitation on the present application. In the drawings:

[0021] Figure 1 The ultraviolet diagram of the copper sulfate solution mixed with EDDHA-Na after reaction. DETAILED DESCRIPTION

[0022] The principles and characteristics of the present application are described below in conjunction with the drawings, the examples are only used to explain the present application, and are not used to limit the scope of the present application.

[0023] The working principle of the present application: EDDHA chelating agent has strong complexation with metal, which is traditionally used in the fields of environmental water pollution control, cosmetic bleaching, cloth bleaching, agricultural fertilizer, etc. The present application adopts copper ion solution, thiosulfate solution, EDDHA-Na mixed preparation gold extract solution, EDDHA-Na mainly complex with copper ion to form complex ion. For example, Figure 1As shown, compared with copper sulfate and EDDHA-Na, EDDHA-Na mixed with copper to form a new absorption peak, indicating that EDDHA-Cu complex ions are formed, reducing the formation of copper-ammonia complex ions, thereby reducing the oxidation and consumption of thiosulfate ions.

[0024] The raw material specifications used in the following examples of the present application are as follows:

[0025] 1. EDDHA-Na, purchased from Shanghai Xihai Chemical Industry.

[0026] 2. Copper sulfate pentahydrate, analytical pure, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0027] 3. Ammonium thiosulfate, analytical pure, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0028] 4. Ammonia, industrial grade, mass fraction of 25-28wt%

[0029] 5. The main elements in the oxidized ore sample and their proportions are shown in Table 1:

[0030] Table 1

[0031]

[0032] Example 1

[0033] 1) 1.776g of ammonium thiosulfate, 3mL of EDDHA-Na were weighed and mixed, then 40mL of ultrapure water was added, stirred and dissolved to prepare a gold extraction solution, marked as S1-1.

[0034] 2) 0.05g, 0.1g, 0.2g, 0.3g, 0.4g, 0.5g of copper sulfate pentahydrate were weighed and mixed with 1.776g of ammonium thiosulfate, 3mL of EDDHA-Na, respectively, then 40mL of ultrapure water was added, stirred and dissolved to prepare a gold extraction solution, respectively marked as S1-2, S1-3, S1-4, S1-5, S1-6, S1-7.

[0035] 3) The oxidized ore sample was weighed and mixed with each group of gold extraction solution prepared in steps 1) and 2) according to the solid-liquid ratio of 1g:4mL, industrial ammonia water was added to adjust the solution pH to 10, a magnetic stirrer was started at a speed of 500r / min for continuous stirring for 24h, then the gold leaching solution was collected after filtration and the gold leaching rate of each group of leaching solution was tested, the results are shown in Table 2.

[0036] Copper ions have important catalytic effect in solution, but the presence of copper ions is one of the reasons for the consumption of thiosulfate ions. In addition, due to the decomposition of thiosulfate ions in the leaching solution and other reasons, unstable copper ions will also form sulfides and other substances that hinder the leaching of gold, thereby making the leaching effect of gold poor. Therefore, the gold leaching rate increases with the increase of copper ion concentration and then decreases.

[0037] Table 2 Gold concentration of each group of leaching solution of Example 1

[0038]

[0039] Comparative Example 1

[0040] 1) Weigh 0.1 g of copper sulfate pentahydrate, 1.776 g of ammonium thiosulfate, and add them to 40 mL of ultrapure water, stir and dissolve to prepare a gold extraction solution.

[0041] 3) Weigh the oxidized ore sample, mix it with the gold extraction solution prepared in step 1) according to the solid-liquid ratio of 1 g:4 mL, add industrial ammonia to adjust the solution pH to 10, start the magnetic stirrer at a speed of 500 r / min, continuously stir and leach for 24 h, filter to collect the gold leaching solution and test the gold leaching rate of each group of leaching solution, which is 35.67%.

[0042] Comparative Example 1 and Example 1 have the same conditions in S1-3 group, the only difference is that EDDHA-Na is not added, and the gold leaching rate is lower than that of S1-3 group. It shows that the formed EDDHA-Cu complex has a positive effect on the dissolution of gold in the system.

[0043] Example 2

[0044] 1) Weigh 0.592 g, 1.776 g, 2.96 g, 4.144 g, 5.82 g of ammonium thiosulfate, respectively, and mix them with 0.1 g of copper sulfate pentahydrate, 5.4 mL of EDDHA-Na, respectively, then add 40 mL of ultrapure water, stir and dissolve to prepare a gold extraction solution, respectively, marked as S2-1, S2-2, S2-3, S2-4, S2-5.

[0045] 2) Weigh the oxidized ore sample, mix it with the gold extraction solution prepared in step 1) according to the solid-liquid ratio of 1 g:4 mL, add industrial ammonia to adjust the solution pH to 10, start the magnetic stirrer at a speed of 500 r / min, continuously stir and leach for 24 h, filter to collect the gold leaching solution and test the gold leaching rate of each group of leaching solution, as shown in Table 3.

[0046] The main role of thiosulfate ion in leaching is to form stable complex ions with gold, but it is easily consumed due to its own reducing property and instability. When its concentration is too low, it cannot sufficiently form complexes with gold ions, and when its concentration is too high, most of it will form complex ions with copper ions, and the copper thiosulfate complex ions formed will oxidize the thiosulfate ions and possibly reduce the gold leaching rate when the concentration is too high.

[0047] Table 3 Gold concentration of each group of leaching solution in Example 2

[0048]

[0049]

[0050] Example 3

[0051] 1) Measure 0.6 mL, 1.8 mL, 3 mL, 4.2 mL, 5.4 mL, 7.8 mL, 0 mL of EDDHA-Na, respectively, and mix with 0.1 g of copper sulfate pentahydrate, 1.776 g of ammonium thiosulfate, respectively, then add 40 mL of ultrapure water, stir and dissolve to prepare gold extraction solution, respectively, and mark as S3-1, S3-2, S3-3, S3-4, S3-5, S3-6, S3-7.

[0052] 2) Weigh the oxidized ore sample and mix it with the gold extraction solution prepared in step 1) according to the solid-liquid ratio of 1 g:4 mL, add industrial ammonia water to adjust the solution pH to 10, start the magnetic stirrer at a speed of 500 r / min for continuous stirring for 24 h, then filter to collect the gold leaching solution and test the gold leaching rate of each group of leaching solution, the results are shown in Table 4.

[0053] When the volume of EDDHA-Na in the solution is small, the effect is small; when the volume of EDDHA-Na in the solution is too large, it will reduce the gold leaching rate because it reduces the oxidizing property of the solution.

[0054] Table 4 Gold concentration of each group of leaching solution in Example 3

[0055]

[0056] Example 4

[0057] 1) Weigh 0.1 g of copper sulfate pentahydrate, 1.776 g of ammonium thiosulfate, and 5.4 mL of EDDHA-Na, mix them, then add 40 mL of ultrapure water, stir and dissolve to prepare gold extraction solution.

[0058] 2) Take the oxidized ore sample, and mix it with the gold extraction liquid prepared in step 1) according to the solid-liquid ratio of 1g: 4mL, respectively. Add industrial ammonia to adjust the solution pH = 10, and start the magnetic stirrer at a speed of 500r / min for continuous stirring leaching. The leaching time is set to 1h, 3h, 6h, 9h, 12h, 24h, 36h, and 48h, respectively, and the groups are recorded as S5-1, S5-2, S5-3, S5-4, S5-5, S5-6, S5-7, and S5-8. After filtering the mixed solutions of each group, the gold leaching liquid is collected and the gold leaching rate of each group of leaching liquid is tested. The results are shown in Table 6.

[0059] The greatest impact of the solid-liquid ratio is on the dosage of the reagent. When the solid-liquid ratio is large, the leaching rate and leaching rate of gold will be low, and when the solid-liquid ratio is small, the leaching rate and leaching rate of gold will theoretically increase. However, after the solid-liquid ratio is increased from 1:9 to 1:12, the gold leaching rate is improved, but the improvement rate is not high.

[0060] Table 5 Gold concentration of each group of leaching liquid in Example 4

[0061]

[0062] Example 5

[0063] 1) Take 0.05g of copper sulfate pentahydrate, 1.776g of ammonium thiosulfate, and 3mL of EDDHA-Na, and mix them. Then add 40mL of ultrapure water and stir to dissolve, to prepare a gold extraction liquid.

[0064] 2) Take the oxidized ore sample, and mix it with the gold extraction liquid prepared in step 1) according to the solid-liquid ratio of 1g: 4mL, respectively. Add industrial ammonia to adjust the solution pH = 10, and start the magnetic stirrer at a speed of 500r / min for continuous stirring leaching. The leaching time is set to 1h, 3h, 6h, 9h, 12h, 24h, 36h, and 48h, respectively, and the groups are recorded as S5-1, S5-2, S5-3, S5-4, S5-5, S5-6, S5-7, and S5-8. After filtering the mixed solutions of each group, the gold leaching liquid is collected and the gold leaching rate of each group of leaching liquid is tested. The results are shown in Table 6.

[0065] Table 6 Gold concentration of each group of leaching liquid in Example 5

[0066]

[0067] Example 6

[0068] 1) Take 0.1g of copper sulfate pentahydrate, 1.776g of ammonium thiosulfate, and 11.7675mL of EDDHA-Na, and mix them. Then add 78.23mL of ultrapure water and stir to dissolve, to prepare a gold extraction liquid.

[0069] 2) Take the oxidized ore sample, divide it into several groups, mix it with the gold extraction liquid prepared in step 1) according to the solid-liquid ratio of 1g:4mL, add concentrated sulfuric acid to one group and industrial ammonia to the rest, and adjust the pH of the solution to 4, 6, 8, 10, and 11 respectively. Denoted as S6-1, S6-2, S6-3, S6-4, and S6-5. Turn on the magnetic stirrer to continuously stir the leaching at a speed of 500r / min, and set the leaching time to 24h respectively. After filtering the mixed solution of each group, collect the gold leaching liquid and test the gold leaching rate of each group of leaching liquid, and the results are shown in Table 7.

[0070] Table 7 Gold concentration of each group of leaching liquid in Example 6

[0071]

[0072] Based on the above several experimental conditions and cost considerations, the best embodiment or optimal experimental condition is: 0.3M S2O3 2- , 0.45M (volume ratio to water 13.5%) EDDHA-Na, pH=10, Cu 2+ concentration 0.01M, solid-liquid ratio 1:9, and extraction time 24h. The corresponding gold extraction rate is 83.47%.

[0073] The above is only a preferred embodiment of the present application, and does not limit the present application in any form; any ordinary skilled person in the industry can easily implement the present application according to the drawings and the above description; however, any equivalent changes, modifications and evolution made by those skilled in the art within the scope of the technical solutions of the present application, using the above disclosed technical content, are equivalent embodiments of the present application; at the same time, any equivalent changes, modifications and evolution of the above embodiments according to the essential technology of the present application are still within the protection scope of the technical solutions of the present application.

Claims

1. A method for preparing a gold extractant, characterized in that, Copper sulfate pentahydrate, ammonium thiosulfate, and EDDHA-Na were mixed in a reaction vessel, water was added, and the mixture was stirred until homogeneous to obtain a gold extractant. In the gold extraction agent, Cu 2+ The molar concentration is 0.01M, S2O3 2- The molar concentration is 0.3M; the volume ratio of EDDHA-Na to water is 13.5%.

2. An application of a gold extractant prepared by the method described in claim 1 in the extraction of gold from minerals, characterized in that, Minerals are added to the gold extractant, and then ammonia is added to adjust the pH of the solution to 8-11. The gold-containing leachate was continuously stirred and leached for 1-48 hours, then filtered to obtain a gold-containing leachate. The stirring speed was 400-600 r / min. The solid-liquid ratio of the mineral to the gold extractant is 1g:3-12mL.

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