Glutamic acid-based leaching reagent and process for extracting mineral resources

Abstract

The application provides a glutamic acid leaching agent and a process for extracting mineral resources, the leaching agent introduces chain and ring structures on the active sites of glutamic acid respectively, and the amino group, the carbonyl group and the mutual cooperation between the chain and ring structures make the leaching agent have the effect of efficiently leaching gold, copper and silver in mineral resources. In the gold, copper and silver leaching process, firstly, the fineness of the ore powder in the ore pulp is controlled, and the concentration of the ore pulp is controlled in a reasonable range; then the glutamic acid leaching agent, an oxidizing agent and a pH regulator are sequentially added into the ore pulp, the oxidizing agent fully oxidizes the metal elements into metal ions, and the pH regulator adjusts the ore pulp to a suitable pH value, the leaching conditions are strictly controlled, the leaching agent firmly combines the metal ions on the molecular chain of the functional group leaching agent in a specific way, and the leaching rate is improved.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, and in particular to a glutamic acid leaching agent and its process for extracting mineral resources. Background Technology

[0002] In hydrometallurgical metal recovery, traditional leaching methods use inorganic acids or cyanides as the main leaching agents. These agents, especially cyanides, cause significant environmental pollution. Therefore, the hydrometallurgical industry is constantly developing various relatively environmentally friendly leaching agents. Among these, sulfur-based leaching (thiosulfates, thiourea, and thiocyanates), halide-based leaching, and ammonium-based leaching have received considerable research. However, each of these systems has its limitations. For example, thiosulfate leaching consumes too much thiosulfate, and the sulfur generated during the reaction easily covers the mineral surface, affecting subsequent leaching and leading to low efficiency. Thiourea and thiocyanate, as potential carcinogens, require further treatment of wastewater and solid waste generated during metal extraction, increasing environmental protection costs for enterprises. Halide systems are highly corrosive, requiring high corrosion resistance in equipment, and halides are expensive. Ammonium-based leaching produces large amounts of ammonia gas, affecting the working environment.

[0003] With the continuous development of the hydrometallurgical industry, amino acids have been increasingly studied. For example, amino acids are used as additives to modify other leaching systems through synergistic effects, achieving the desired purpose. Feng and Van Deventer (2011, The role of amino acids in the thiosulphate leaching of gold. Miner. Eng. 24(9), 1022-1024) introduced amino acids as additives into the thiosulfate leaching system and studied the effects of different types of amino acids (glycine, L-valine, DL-α-alanine and L-histidine) on copper-sulfur gold concentrate. The study found that by adding 10 mM valine, glycine, alanine, and histidine respectively, and leaching for 24 hours, the consumption of thiosulfate decreased from 12.6 kg / t to 6.6 kg / t, 6.3 kg / t, 5.2 kg / t, and 4.5 kg / t, respectively. The addition of amino acids reduced the amount of thiosulfate used to some extent, but amino acids still do not play a major role and are only an additive. The reaction system still requires the addition of a large amount of salts, a variety of reagents are used, and the environmental pressure is relatively high.

[0004] Patent publication number WO2015031943A1 discloses a process for recovering copper and / or precious metals. While exploring the feasibility of extracting metal resources using a glycine leaching system with pure metals, it was found that in most cases, using amino acids (glycine) alone as a leaching agent did not achieve satisfactory results; cyanide had to be used in combination to achieve the desired effect. Therefore, Eksteen and Oraby (2021, Elimination of most of the cyanide requirement and concomitant effluent during precious metals extraction from waste printed circuit boards. Waste Manag. 125, 87-97) used a glycine-cyanide co-leaching process (i.e., amino acids were still used as an additive) to treat electronic waste and extract metal resources. However, cyanide is highly toxic and causes serious environmental pollution, and is still not an ideal leaching system.

[0005] In view of this, it is necessary to design an improved glutamic acid leaching agent and its extraction process for mineral resources in order to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a glutamic acid-based leaching agent and its process for extracting mineral resources. Chain-like and cyclic structures are introduced into the active sites of glutamic acid, and the synergistic effects between amino groups, carbonyl groups, and the chain-like and cyclic structures are utilized to achieve highly efficient leaching of gold, copper, and silver from mineral resources. In the gold, copper, and silver leaching process, this invention, through strict control of leaching conditions, enables the leaching agent to firmly bind metal ions to the molecular chain of the functional group leaching agent in a specific manner, thereby improving the leaching rate.

[0007] To achieve the above-mentioned objective, the present invention provides a glutamic acid-based leaching agent, comprising one of glutamic acid and a glutamic acid derivative; wherein the glutamic acid derivative comprises one of a first glutamic acid derivative derived from an amino group, a second glutamic acid derivative derived from a carboxyl group, or a third glutamic acid derivative cyclized from glutamic acid.

[0008] The general structural formula of the first glutamic acid derivative is:

[0009]

[0010] In the formula, R1 is one of alkyl or acyl groups;

[0011] The general structural formula of the second glutamic acid derivative is:

[0012]

[0013] In the formula, R2 is one of alkoxy or stereocyclic structures;

[0014] The structural formula of the third glutamic acid derivative is:

[0015] .

[0016] As a further improvement of the present invention, in the general structural formula of the first glutamic acid derivative, R1 is one of methyl, ethyl, or acetyl groups.

[0017] As a further improvement of the present invention, in the general structural formula of the second glutamic acid derivative, R2 is one of methoxy, ethoxy, R2-A, and R2-B;

[0018] Among them, R 2-A The structural formula is:

[0019]

[0020] R 2-B The structural formula is:

[0021]

[0022] This invention also provides a process for extracting mineral resources, using the aforementioned glutamic acid-based leaching agent, comprising the following steps:

[0023] S1. Grind the mineral resource to be tested to a particle size of less than 100 mesh to obtain mineral powder, add water to the mineral powder and stir to obtain a mineral slurry of a preset concentration;

[0024] S2. Add one or more of the glutamic acid leaching agents to the slurry to bring the glutamic acid leaching agent to a preset concentration;

[0025] S3. Next, add an oxidant and a pH adjuster to adjust the slurry to alkaline. Stir the slurry at a temperature of 20-80℃ for 6-72 hours to extract gold, copper, and silver from the mineral resources.

[0026] As a further improvement of the present invention, in step S1, the mineral resources include natural minerals and secondary minerals.

[0027] As a further improvement of the present invention, in step S2, the preset concentration of the glutamic acid leaching agent in the slurry is 0.5-2 mol / L.

[0028] As a further improvement of the present invention, in step S1, the portion of the mineral powder with a particle size of less than 100 mesh accounts for 90% of the total mass of the mineral powder; the mass concentration of the slurry is 5%-10%.

[0029] As a further improvement of the present invention, in step S3, the oxidant is one or more of hydrogen peroxide, sodium hypochlorite, and potassium permanganate; the concentration of the oxidant in the slurry is 0.05-0.2 mol / L.

[0030] As a further improvement of the present invention, the pH adjuster is one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, calcium oxide, sodium phosphate, sodium monohydrogen phosphate, sodium dihydrogen phosphate, and sodium phosphate; the slurry is adjusted to a pH of 8-14.

[0031] As a further improvement of the present invention, in step S3, the stirring speed is 50-150 r / min.

[0032] The beneficial effects of this invention are:

[0033] (1) This invention uses glutamic acid as the molecular backbone, modifies glutamic acid, introduces chain-like and cyclic structures on its active sites, and utilizes the synergistic effect between amino groups, carbonyl groups and chain-like and cyclic structures to make it have the effect of efficiently leaching gold, copper and silver from mineral resources.

[0034] In the leaching of gold, copper, and silver, the mineral powder in the slurry is first controlled to a certain fineness, and the slurry concentration is controlled within a relatively low range according to the composition and content of the selected mineral resources, thereby initially improving the leaching rate of gold, copper, and silver in the mineral powder. Then, an appropriate concentration of glutamic acid leaching agent, oxidant, and pH adjuster are added sequentially. The oxidant fully oxidizes the elemental metal into metal ions, while the pH adjuster adjusts the slurry to a suitable acidity or alkalinity. The glutamic acid leaching agent of this invention strictly controls the type, number, and positional relationship of functional groups in the glutamic acid molecular chain, as well as the length of the molecular chain. Through the synergistic effect between functional groups, it enables the metal ions to be firmly bound to the functional groups of the molecular chain of the functional group leaching agent in a specific manner. The functional groups in this multifunctional leaching agent more easily and firmly chelate metal ions (gold, copper, and silver) in the functional groups of its molecular chain, thereby improving the leaching rate.

[0035] (2) The glutamic acid-based leaching agent of the present invention plays a major role in the leaching system, eliminating the need to add thiosulfate or cyanide to the entire leaching system. This breaks the traditional amino acid-cyanide synergistic system, making the leaching system green and environmentally friendly. At the same time, it expands the types of traditional leaching agents and provides ideas and screening directions for the subsequent search for new leaching agents that can be industrialized and used on a large scale. Attached Figure Description

[0036] Figure 1This is a synthetic route diagram of the glutamic acid extractants used in Examples 5-6 and Comparative Examples 16-19.

[0037] Figure 2 for Figure 1 The structural formula of a mesocyclic alcohol. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0040] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0041] This invention provides a glutamic acid-based leaching agent, comprising one of glutamic acid and glutamic acid derivatives; the glutamic acid derivatives include one of a first glutamic acid derivative derived from an amino group, a second glutamic acid derivative derived from a carboxyl group, or a third glutamic acid derivative cyclized from glutamic acid;

[0042] The general structural formula of the first glutamate derivative:

[0043]

[0044] In the formula, R1 is one of alkyl or acyl groups; preferably one of methyl, ethyl, or acetyl groups.

[0045] General structural formula of second glutamate derivatives:

[0046]

[0047] In the formula, R2 is one of alkoxy or stereocyclic structure; preferably one of methoxy, ethoxy, R2-A, or R2-B.

[0048] Among them, R 2-A The structural formula is:

[0049]

[0050] R 2-B The structural formula is:

[0051]

[0052] The structural formula of the third glutamic acid derivative is:

[0053] .

[0054] This invention also provides a process for extracting mineral resources, using the aforementioned glutamic acid-based leaching agent, comprising the following steps:

[0055] S1. Preparation of slurry:

[0056] The mineral resource to be tested is ground to a particle size of less than 100 mesh to obtain mineral powder, ensuring that the portion of the mineral powder with a particle size of less than 100 mesh accounts for 90% of the total mass of the mineral powder. Then, water is added to the mineral powder and stirred to obtain a slurry with a mass concentration of 5%-10%.

[0057] The mineral resources include natural minerals and secondary minerals. Secondary minerals are preferably electronic waste. The accumulation of electronic waste not only wastes resources but also pollutes the environment and occupies a large amount of space. The glutamic acid-based leaching agent of this application can extract heavy metals from electronic waste, making rational use of resources while protecting the environment, and has significant practical value.

[0058] By controlling the portion of mineral powder with a particle size smaller than 100 mesh to 90% of the total mineral powder mass, the mineral powder in the prepared slurry is kept at a certain fineness, which is more conducive to the leaching of copper and gold from the mineral powder and improves the leaching rate.

[0059] S2. Add glutamate-based extractants:

[0060] One or more glutamic acid leaching agents are added to the slurry to make the total concentration of glutamic acid leaching agents in the slurry 0.5-2 mol / L.

[0061] S3. Add oxidant and pH adjuster:

[0062] Next, an oxidant is added to the slurry, ensuring that the concentration of the oxidant in the slurry is 0.05-0.2 mol / L. The oxidant can be one or more of hydrogen peroxide, sodium hypochlorite, and potassium permanganate.

[0063] Next, a pH adjuster is added to the slurry to adjust it to alkalinity, bringing the pH value to 8-14. The slurry is then stirred at a temperature of 20-80℃ for 6-72 hours at a stirring speed of 50-150 r / min to extract gold, copper, and silver from the mineral resources. The pH adjuster is one or more of the following: sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, calcium oxide, sodium phosphate, sodium monohydrogen phosphate, sodium dihydrogen phosphate, and sodium phosphate.

[0064] In this process, the oxidant fully oxidizes the elemental metals in the mineral resources into metal ions, while the pH adjuster adjusts the slurry to a suitable acidity or alkalinity, allowing the metal ions to interact better with the glutamic acid-based leaching agent, thereby increasing the metal leaching rate. Specifically, the special functional groups (chain-like, cyclic structures, and carbonyl and amino groups with specific structures) in the molecular structure of the glutamic acid-based leaching agent undergo chelation reactions with the metal ions, firmly binding the metal ions to the molecular chain of the functional group leaching agent in a specific manner, forming a soluble metal ligand complex.

[0065] Compared to traditional leaching agents (chelating agents), such as disodium ethylenediaminetetraacetate (EDTA), polyacetylimide (PEI), biodegradable ethylenediaminedisuccinic acid (EDDS), tetrasodium glutamate diacetate (GLDA), and iminodiacetic acid (IDSA), the glutamate-based leaching agent of this application, by rationally controlling the positional relationship between amino and carbonyl groups, as well as the length of the molecular chain and the specific structure of the ring, utilizes the synergistic effect of each structure to more easily and firmly chelate metal ions (gold, copper, silver) in its molecular chain, thereby improving the leaching rate.

[0066] The present invention will be described below through specific embodiments. In the following embodiments, waste circuit boards containing metal resources (a type of electronic waste) are selected. The main components of the waste circuit boards are shown in Table 1. Among them, the units of Au, Ag, Pt and Pd are g / t.

[0067] Table 1 Main Components of Waste Circuit Boards

[0068]

[0069] Example 1

[0070] A process for extracting mineral resources includes the following steps:

[0071] S1. Preparation of slurry:

[0072] The above-mentioned electronic waste is ground to a particle size of less than 100 mesh to obtain mineral powder, ensuring that the portion of the mineral powder with a particle size of less than 100 mesh accounts for 90% of the total mass of the mineral powder. Then, water is added to the mineral powder and stirred to obtain a slurry with a mass concentration of 5%.

[0073] S2. Add glutamate-based extractants:

[0074] Glutamic acid was added to the slurry to make the total concentration of glutamic acid leaching agents in the slurry 1 mol / L.

[0075] S3. Add oxidant and pH adjuster:

[0076] Next, sodium hypochlorite is added to the slurry to ensure that the concentration of sodium hypochlorite in the slurry is 0.2 mol / L.

[0077] Sodium hydroxide was added to the slurry to adjust it to alkalinity, and the pH value of the slurry was adjusted to 12. The slurry was stirred at 20°C for 36 hours at a stirring speed of 100 r / min to extract gold, copper and silver from the mineral resources.

[0078] Examples 2-7

[0079] A process for extracting mineral resources differs from Example 1 in that the type of glutamic acid leaching agent added in step S2 is different; otherwise, it is largely the same as Example 1 and will not be described in detail here.

[0080] The leaching rates of gold, copper, and silver in Examples 1-7 are shown in Table 1:

[0081] Table 1. Leaching rates of gold, copper, and silver in Examples 1-7

[0082]

[0083]

[0084] Table 1 shows that the structure of glutamic acid leaching agents has a significant impact on the leaching rates of gold, copper, and silver. The glutamic acid leaching agents in Examples 2, 5, 6, and 7 showed better leaching effects on gold, copper, and silver, while the glutamic acid leaching agents in Examples 1, 3, and 4 showed similar leaching rates for gold and copper. This may be because the presence of acetyl groups in Examples 2 and 7 enhances the ability of the carbonyl and amine groups (lone pair electrons of the nitrogen atom) to synergistically complex metal ions, and the special cyclic structures in Examples 5 and 6 better promote the capture of metal ions, thus resulting in higher leaching rates of gold, copper, and silver.

[0085] Example 8 and Comparative Example 1

[0086] A process for extracting mineral resources differs from Example 2 in that the slurry concentration is different in step S1, but otherwise it is largely the same as Example 2 and will not be described again here.

[0087] The leaching rates of gold, copper, and silver in Example 8 and Comparative Example 1 are shown in Table 2:

[0088] Table 2 shows the leaching rates of gold, copper, and silver in Example 8 and Comparative Example 1.

[0089]

[0090]

[0091] Table 2 shows that the leaching rates of gold, copper, and silver gradually decrease with increasing pulp concentration. This may be because, on the one hand, increasing pulp concentration affects the mass transfer between the reaction liquid and solid during the leaching process, ultimately affecting the effective complexation of the leaching reagent with metal ions; on the other hand, it affects the relative molar ratio of the leaching reagent to the leached metal in the mineral. When the pulp concentration is higher than 10%, the amount of reagent used is relatively insufficient, and the metal resources in the electronic waste cannot be effectively leached. In addition, since the copper content in the selected electronic waste is relatively high, excessively high pulp concentration causes the copper-complex originally leached by the leaching reagent to precipitate out of the solution system, and also affects the leaching of other metals.

[0092] When the slurry concentration is too low (<5%), it is not conducive to industrial production. For example, it wastes water resources and generates a large amount of wastewater. In order to achieve environmentally friendly wastewater discharge, it will further increase the environmental protection costs of enterprises.

[0093] Other glutamate-based leaching agents have similar effects on the leaching rates of gold, copper, and silver depending on the pulp concentration.

[0094] Examples 9-10 and Comparative Examples 2-3

[0095] A process for extracting mineral resources differs from Example 2 in that the concentration of the glutamic acid leaching agent is different in step S2. Otherwise, it is largely the same as Example 2 and will not be described again here.

[0096] The leaching rates of gold, copper, and silver in Examples 9-10 and Comparative Examples 2-3 are shown in Table 3.

[0097] Table 3 shows the leaching rates of gold, copper, and silver in Implementation 9-10 and Comparative Examples 2-3.

[0098]

[0099] Table 3 shows that as the concentration of glutamate-based leaching agents increases, the leaching rates of gold and copper gradually increase and then stabilize, while the leaching rate of silver shows a trend of first increasing and then decreasing. When the concentration of glutamate-based leaching agents is too high (≥2.5 mol / L), the leaching rates of gold and copper no longer increase. When the concentration of glutamate-based leaching agents is too low (≤0.5 mol / L), the leaching effects of gold, copper, and silver are all poor. This is because the amount of leaching agent is insufficient, and the metals in the electronic waste cannot react completely with the leaching agent. This trend is more pronounced when the concentration of glutamate-based leaching agents is below 0.5 mol / L.

[0100] Examples 11-12 and Comparative Examples 4-5

[0101] A process for extracting mineral resources differs from Example 2 in that the concentration of the oxidant is different in step S3. Otherwise, it is largely the same as Example 2 and will not be described again here.

[0102] The leaching rates of gold, copper, and silver in Examples 11-12 and Comparative Examples 4-5 are shown in Table 4:

[0103] Table 4 shows the leaching rates of gold, copper, and silver in Examples 11-12 and Comparative Examples 7-8.

[0104]

[0105] As shown in Table 4, with the continuous increase of oxidant concentration, the leaching rates of gold and copper initially increased significantly and then stabilized, while the leaching rate of silver showed a trend of first increasing and then decreasing. When the oxidant concentration was too low, the leaching rates of gold, copper, and silver were significantly lower. This is mainly because a small amount of oxidant cannot fully oxidize the elemental metals into metal ions, thus affecting their complexation with the leaching agent and consequently affecting the leaching rates of gold, copper, and silver.

[0106] Other glutamate-based leaching agents have similar effects on the leaching rate of gold, copper, and silver depending on the concentration of the oxidant.

[0107] Examples 13-14

[0108] A process for extracting mineral resources differs from Example 2 in that the type of oxidant used in step S3 is different; otherwise, it is largely the same as Example 2 and will not be described again here.

[0109] The leaching rates of gold, copper, and silver in Examples 13-14 are shown in Table 5:

[0110] Table 5 shows the leaching rates of gold, copper, and silver in implementations 13-14.

[0111]

[0112] As shown in Table 5, the leaching effects of the three oxidants on gold and copper are in the following order: sodium hypochlorite is superior to hydrogen peroxide, and hydrogen peroxide is superior to potassium permanganate. This is because potassium permanganate, as an oxidant, reacts to form manganese dioxide precipitate, which coats the surface of the electronic waste, affecting the contact between the electronic waste and the leaching solution.

[0113] Other multifunctional leaching agents have similar effects on the leaching rates of gold, copper, and silver, depending on the type of oxidant.

[0114] Examples 15-16 and Comparative Examples 6-7

[0115] A process for extracting mineral resources differs from Example 2 in that the pH value of the slurry is different after adjustment with a pH adjuster in step S3. Otherwise, it is largely the same as Example 2 and will not be described in detail here.

[0116] The leaching rates of gold, copper, and silver in Examples 15-16 and Comparative Examples 6-7 are shown in Table 6.

[0117] Table 6 shows the leaching rates of gold, copper, and silver in Examples 15-16 and Comparative Examples 6-7.

[0118]

[0119] Table 6 shows that glutamic acid leaching agents exhibit poor leaching effects on gold and silver at a pH of 7. Under acidic conditions, glutamic acid leaching agents no longer have a leaching effect on gold and silver. This is mainly because the carboxyl groups in the leaching agents exist in an electrically neutral molecular form and cannot effectively complex with gold and silver, resulting in the inability to leach them. Simultaneously, the leaching rate of copper is low. As the pH of the leaching system increases, the carboxyl groups in the leaching agents hydrolyze into anionic forms, and the pH of the leaching system has a smaller impact on the leaching effect on metals.

[0120] Other glutamate-based leaching agents have similar effects on the leaching rate of gold and copper depending on the pH value.

[0121] Examples 17-18 and Comparative Examples 8-9

[0122] A process for extracting mineral resources differs from Example 5 in that the concentration of the glutamic acid leaching agent is different in step S2. Otherwise, it is largely the same as Example 5 and will not be described again here.

[0123] The leaching rates of gold, copper, and silver in Examples 17-18 and Comparative Examples 8-9 are shown in Table 7.

[0124] Table 7 shows the leaching rates of gold, copper, and silver in Examples 17-18 and Comparative Examples 8-9.

[0125]

[0126] As shown in Table 7, the leaching effect of gold and silver is poor when the concentration is too low (≤0.5mol / L); when the concentration of glutamic acid leaching agent is too high (≥2.5mol / L), the leaching rate of gold, copper and silver not only does not increase, but decreases instead.

[0127] Comparative Example 10

[0128] A process for extracting mineral resources, compared with Example 1, differs in that the leaching agent added in step S2 is EDTA. The rest is largely the same as Example 1 and will not be repeated here. In Comparative Example 10, the copper leaching rate was 92%, the silver leaching rate was 37%, and gold could not be leached. This further illustrates that the glutamic acid-based leaching agent of this application has a structure that more easily and firmly chelates metal ions (copper, gold, and silver) in its molecular chain, thereby improving the leaching rate.

[0129] Comparative Example 11

[0130] A process for extracting mineral resources differs from Example 2 in that glycine is added as the leaching agent in step S2. The rest is largely the same as Example 2 and will not be repeated here. In Comparative Example 11, the gold leaching rate was 62%, the copper leaching rate was 87%, and the silver leaching rate was 65%. The effect of Comparative Example 11 is significantly worse than that of Example 2, indicating that glycine has a generally poor leaching effect on metals in electronic waste of specific components and cannot meet the needs of the increasingly diverse types of electronic waste.

[0131] Comparative Example 12

[0132] A process for extracting mineral resources differs from Example 2 in that, in step S2, the added leaching agent is glycine and cyanide, specifically at a concentration of 1 mol / L glycine and 1500 g / t sodium cyanide (i.e., 1500 g sodium cyanide is needed for one ton of electronic waste). Other steps are largely the same as in Example 2 and will not be repeated here. In Comparative Example 12, the gold leaching rate was 82%, the silver leaching rate was 85%, and the copper leaching rate was 92%. While Comparative Example 12 achieved good results, it required the use of highly toxic cyanide. This application, by modifying the structure of glutamic acid, achieves excellent leaching results using only this leaching agent, without the need for cyanide.

[0133] Comparative Example 13

[0134] A process for extracting mineral resources differs from Example 2 in that, in step S2, the R1 group in the added leaching agent is a propionyl group. The other steps are largely the same as in Example 2 and will not be repeated here. In Comparative Example 13, the gold leaching rate was 7%, the copper leaching rate was 67%, and the silver leaching rate was 19%. The effect of Comparative Example 13 was significantly worse than that of Example 2. This is partly because the steric hindrance of the propionyl group affects the complexation between the leaching agent and metal ions, thus affecting the leaching rate of metal ions; and partly because, with the increase of the carbon chain of the R1 functional group in the molecular structure of the first glutamic acid derivative leaching agent, the solubility of the agent itself in water deteriorates.

[0135] Comparative Example 14

[0136] A process for extracting mineral resources differs from Example 3 in that, in step S2, R1 in the added leaching agent is propyl. The other steps are largely the same as in Example 3 and will not be repeated here. In Comparative Example 14, metal leaching was practically impossible because the solubility of the agent in water decreased with the increase of the carbon chain in the R1 functional group.

[0137] Comparative Example 15

[0138] A process for extracting mineral resources differs from Example 4 in that, in step S2, R2 in the added leaching agent is propoxylated. The other steps are largely the same as in Example 4 and will not be repeated here. In Comparative Example 15, metal could not be leached because when R2 is propoxylated, the agent itself has poor solubility in water.

[0139] Comparative Example 16

[0140] A process for extracting mineral resources differs from Example 5 in that the structure of the leaching agent added in step S2 is different, as shown below. The rest is largely the same as in Example 5 and will not be described again here.

[0141]

[0142] Comparative Example 17

[0143] A process for extracting mineral resources differs from Example 5 in that the structure of the leaching agent added in step S2 is different, as shown below. The rest is largely the same as in Example 5 and will not be described again here.

[0144]

[0145] Comparative Examples 16-17 could hardly achieve metal leaching. This is mainly because as the R2 functional group in the molecular structure of the first glutamic acid derivative leaching agent is introduced into a ring structure composed entirely of carbon, the solubility of the agent in water deteriorates, making it unable to dissolve in water and thus resulting in the agent not having a leaching effect.

[0146] Comparative Example 18

[0147] A process for extracting mineral resources differs from Example 5 in that the structure of the leaching agent added in step S2 is different (the specific structure is shown below). Otherwise, it is largely the same as Example 5 and will not be described again here. In Comparative Example 18, the gold leaching rate was 37%, the copper leaching rate was 83%, and the silver leaching rate was 53%. The effect of Comparative Example 18 was significantly worse than that of Example 5.

[0148]

[0149] Comparative Example 19

[0150] A process for extracting mineral resources differs from Example 5 in that the structure of the leaching agent added in step S2 is different (the specific structure is shown below). Otherwise, it is largely the same as Example 5 and will not be described again here. In Comparative Example 19, the gold leaching rate was 42%, the copper leaching rate was 81%, and the silver leaching rate was 59%. The effect of Comparative Example 19 is significantly worse than that of Example 5.

[0151]

[0152] As can be seen from the data of Comparative Examples 18-19, with the introduction of furan ring structure into the R2 functional group of the first glutamic acid derivative leaching agent molecule, although there is no problem of poor solubility of the agent in water, the leaching effect of the agent is not outstanding due to the difference between the five-membered ring and the six-membered ring structure. This indicates that only a specific ring structure can achieve a better leaching effect.

[0153] Specifically, such as Figure 1 As shown, the preparation methods of the glutamic acid-based extractants in Examples 5-6 and Comparative Examples 16-19 are as follows:

[0154] S1. Glutamic acid and copper sulfate pentahydrate were added to deionized water at a molar ratio of 2:(0.8-1). The pH of the system was adjusted to 10±0.2 with sodium hydroxide. Hydrogen peroxide was added so that its volume accounted for 10-30% of the total volume. The mixture was stirred at 60℃ for 12 hours. Subsequently, the solution was evaporated to 20% of its original volume, filtered, and the filter cake was washed 2-5 times with a small amount of deionized water to obtain the glutamic acid-copper complex.

[0155] S2. Preheat the reactor (preset temperature 50-80℃). When the reactor temperature reaches 40℃, add the glutamic acid-copper complex, cyclic alcohol, and tetrabutyl titanate catalyst. Control the stirring speed to 10 r / min and preheat at 50-80℃ for 10-15 min. During stirring, perform nitrogen purging 3-5 times to prevent oxidation side reactions of air inside the reactor. Glutamic acid-copper complex and cyclic alcohol (structure as shown) Figure 2 The molar ratio of tetrabutyl titanate to cyclic alcohol is 1.5-1.8:1, and the molar ratio of tetrabutyl titanate to cyclic alcohol is 0.5‰-1‰:1.

[0156] Continue heating. When the temperature inside the reactor reaches 100-120℃, gradually increase the stirring speed until it reaches 50 r / min. While maintaining the stirring speed at 50 r / min, purge with nitrogen to 120-150 kPa. The raw material undergoes pressurized esterification under nitrogen atmosphere for 4-8 hours. After the reaction, transfer the product to a container and dissolve it in deionized water. Then, add sodium sulfide, with a molar ratio of 0.8-1 times that of glutamic acid. Filter, collect the filtrate, and distill under reduced pressure. Finally, acidify, precipitate cold, collect the solid, and dry to obtain the corresponding glutamic acid extractant. Figure 2 The cyclic alcohols shown in af correspond sequentially to the structures of the glutamic acid extractants in Examples 16, 17, 18, 19, 5, and 6.

[0157] In summary, this invention provides a glutamic acid-based leaching agent and its process for extracting mineral resources. It introduces planar and three-dimensional structures onto the active sites of glutamic acid, and utilizes the synergistic effects between amino groups, carbonyl groups, and the three-dimensional structures to achieve highly efficient leaching of gold, copper, and silver from mineral resources. In the gold, copper, and silver leaching process, this invention, through strict control of leaching conditions, allows the leaching agent to firmly bind metal ions to the molecular chain of the functional group leaching agent in a specific manner, thereby improving the leaching rate. The glutamic acid-based leaching agent of this invention plays a major role in the leaching system, eliminating the need for the addition of thiosulfate or cyanide, breaking away from the traditional amino acid-salt synergistic system. This leaching system is green and environmentally friendly.

[0158] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A process for extracting mineral resources, characterized in that, The extraction of mineral resources is carried out using glutamate-based leaching agents, wherein the glutamate-based leaching agents include glutamate derivatives derived from carboxyl groups, and the general structural formula of the glutamate derivatives is: ； In the formula, R2 is R 2-A R 2-B One of them; Among them, R 2-A The structural formula is: ； R 2-B The structural formula is: ； The process for extracting mineral resources includes the following steps: S1. Grind the mineral resource to be tested to a particle size of less than 100 mesh to obtain mineral powder, add water to the mineral powder and stir to obtain a mineral slurry of a preset concentration; S2. Add the glutamic acid leaching agent to the slurry to bring the glutamic acid leaching agent to a preset concentration; S3. Next, add an oxidant and a pH adjuster to adjust the slurry to alkaline. Stir the slurry at a temperature of 20-80℃ for 6-72 hours to extract gold, copper, and silver from the mineral resources.

2. The process for extracting mineral resources according to claim 1, characterized in that, In step S1, the mineral resources include natural minerals and secondary minerals.

3. The process for extracting mineral resources according to claim 1, characterized in that, In step S2, the preset concentration of the glutamic acid leaching agent in the slurry is 0.5-2 mol / L.

4. The process for extracting mineral resources according to claim 1, characterized in that, In step S1, the mass concentration of the slurry is 5%-10%.

5. The process for extracting mineral resources according to claim 1, characterized in that, In step S3, the oxidant is one or more of hydrogen peroxide, sodium hypochlorite, and potassium permanganate; the concentration of the oxidant in the slurry is 0.05-0.2 mol / L.

6. The process for extracting mineral resources according to claim 1, characterized in that, The pH adjuster is one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, calcium oxide, sodium monohydrogen phosphate, sodium dihydrogen phosphate, and sodium phosphate; the slurry is adjusted to a pH of 8-14.

7. The process for extracting mineral resources according to claim 1, characterized in that, In step S3, the stirring speed is 50-150 r / min.

Images