Low-toxicity and environment-friendly gold beneficiation method

Abstract

The application discloses a low-toxicity and environment-friendly gold beneficiation method, which comprises the following steps: mixing gold ore with water to obtain slurry A, adding sodium citrate into the slurry A to obtain slurry B, grinding the slurry B to obtain slurry C, wherein the particle size of more than 90% of the ore powder particles in the slurry C is 50-100 mu m; adding a flotation agent into the slurry C to obtain rough selected ore, mixing the rough selected ore with water to obtain slurry D, adding ammonia water into the slurry D to adjust the pH value, adding a pretreatment agent into the slurry D to obtain fine selected ore after stirring and filtering, wherein the pretreatment agent comprises sodium persulfate, methyl isobutyl carbinol, low alcohol, sodium dodecyl sulfate and water; mixing the fine selected ore with water to obtain slurry E, adding a composite leaching agent into the slurry E to obtain leaching liquid, and obtaining gold mud from the leaching liquid by using a displacement method. The application solves the problem of difficult exposure of gold particles in the refractory gold ore, and improves the gold extraction efficiency by using the composite environment-friendly gold extraction agent for gold leaching.

Description

Technical Field

[0001] This invention belongs to the field of gold ore beneficiation technology, specifically relating to a low-toxicity and environmentally friendly gold ore beneficiation method. Background Technology

[0002] Gold is a chemically stable and highly corrosion-resistant precious metal. It is not only a special currency used for reserves and investment, but also an important material for the jewelry, electronics, modern communications, and aerospace industries. Currently, the main method for extracting gold from mines is the cyanide process, which is simple and inexpensive. However, the cyanide used is highly toxic, causing serious pollution and harm to the environment and humans. With the continuous advancement of mineral processing technology, environmentally friendly gold extraction agents aimed at replacing sodium cyanide are constantly being developed and innovated. These agents mainly include thiourea and thiosulfate, which are less toxic and safer to use than cyanide. However, their gold extraction efficiency and stability still need further improvement. In particular, with the large-scale development and utilization of gold resources, easily leached gold ore resources are gradually being depleted, and difficult-to-leach gold ore has gradually become the main development target. In difficult-to-leach gold ore, gold particles are encased in symbiotic minerals, and grinding cannot expose the gold, making it difficult for the gold particles to contact the leachate. At the same time, gold ore contains a large amount of clay minerals, which not only deteriorate the performance of the pulp but also adsorb dissolved gold. Therefore, how to expose the gold particles in difficult-to-leach gold ore and design efficient and low-toxicity environmentally friendly gold extraction agents are currently difficult problems that need to be solved in the development and utilization of gold mines. Summary of the Invention

[0003] To address the aforementioned shortcomings, this invention discloses a low-toxicity and environmentally friendly gold beneficiation method that solves the problem of difficult gold particle exposure in refractory gold ores. Furthermore, it employs a composite environmentally friendly gold extraction agent to replace sodium cyanide for gold leaching, thereby improving gold extraction efficiency.

[0004] This invention is achieved using the following technical solution:

[0005] A low-toxicity and environmentally friendly gold ore beneficiation method includes the following steps:

[0006] (1) Gold ore is mixed with water to obtain slurry A, the solid-liquid ratio of slurry A is 1g: (3-5)mL, sodium citrate is added to slurry A and stirred for 20-30min to obtain slurry B, the mass ratio of slurry A to sodium citrate is 100: (0.05-0.1), and then slurry B is ground to obtain slurry C, the particle size of more than 90% of the mineral powder particles in slurry C is 50-100μm;

[0007] (2) Add flotation agent to the slurry C obtained in step (1) to obtain rougher ore by flotation. The mass ratio of slurry C to flotation agent is 100:(0.1~0.2). The flotation agent includes the following components in parts by weight: 1~5 parts butyl xanthate, 10~20 parts lactic acid, and 0.2~0.5 parts sodium hexametaphosphate.

[0008] (3) Add water to the rough ore obtained in step (2) to make slurry D. The solid-liquid ratio of slurry D is 1g: (5-8)mL. Then add ammonia water to slurry D to adjust the pH value to 7.5-8.5. Then add pretreatment agent to slurry D and stir for 20-30min. Then filter to obtain fine ore. The mass ratio of slurry D to pretreatment agent is 100: (0.02-0.03). The pretreatment agent includes the following components in parts by weight: 1-3 parts sodium persulfate, 3-5 parts methyl isobutyl methanol, 3-5 parts lower alcohol, 1-3 parts sodium dodecyl sulfate, and 30-40 parts water.

[0009] (4) Add water to the selected ore obtained in step (3) to make slurry E. The solid-liquid ratio of slurry E is 1g:(3-5)mL. Then add leaching agent to slurry E and stir to leach for 3-5h. Then filter to obtain leachate. Use displacement method to obtain gold mud from leachate. The mass ratio of slurry E to leaching agent is 1000:(0.2-0.5). The leaching agent includes the following raw materials in parts by weight: 20-40 parts of thiourea, 10-20 parts of sodium bicarbonate, and 1-5 parts of mineral salt. The leaching agent is obtained by mixing the raw material components and reacting them at high temperature.

[0010] Furthermore, in step (1), sodium citrate is added to slurry A and mixed for 20-30 minutes under stirring conditions at a speed of 500-600 r / min to obtain slurry B. Strictly controlling the stirring speed can improve the uniform dispersion of sodium citrate in slurry B, which is beneficial to promoting the dissolution of silicates and clays in gold ore.

[0011] Furthermore, in step (3), the slurry D is first ground to make more than 90% of the mineral powder particles in the slurry D have a particle size of 10-20 μm. Then, ammonia water and pretreatment agent are added sequentially for further treatment. Grinding the slurry D to obtain ultrafine mineral powder particles is beneficial for the contact and interaction between the mineral powder particles and the pretreatment agent, thereby fully exposing the gold particles and improving the efficiency of subsequent gold leaching.

[0012] Furthermore, in step (3), a pretreatment agent is added to slurry D and treated for 20-30 minutes under stirring conditions at a speed of 200-300 r / min. Strictly controlling the stirring speed can ensure that the pretreatment agent and the mineral powder particles are in full contact and can also ensure that bubbles are generated uniformly under the action of methyl isobutyl methanol and lower alcohols, which is beneficial to the contact between sodium persulfate in the pretreatment agent and the mineral powder particles.

[0013] Furthermore, the lower alcohol mentioned in step (3) is either propylene glycol or butanediol.

[0014] Furthermore, in step (4), a leaching agent and a dispersant are added to slurry E and stirred for leaching for 3-5 hours. The mass ratio of the dispersant to the leaching agent is 1:(2-3). The dispersant comprises the following components in parts by weight: 10-20 parts of dodecyl dimethyl betaine and 5-8 parts of butanediol or ethylene glycol. The dispersant prepared by adding dodecyl dimethyl betaine and butanediol or ethylene glycol can effectively improve the dispersibility of the leaching agent in the slurry and improve the leaching effect of the leaching agent. At the same time, it can also prevent the mineral powder from agglomerating during the leaching process and affecting the leaching of gold.

[0015] Furthermore, in step (4), the specific method for preparing the leaching agent is to first mix thiourea, sodium bicarbonate, and mineral salt and react them at 100–200°C for 20–30 min, and then react them at 500–700°C for 30–45 min to obtain the leaching agent. First, thiourea, sodium bicarbonate, and mineral salt are mixed and reacted at low temperature to generate the intermediate product sodium cyanate, and then further reacted at high temperature to obtain a composite gold extraction agent. This stepwise reaction can reduce the generation of by-products and improve the yield of active ingredients.

[0016] Compared with existing technologies, this technical solution has the following advantages:

[0017] 1. In this invention, when gold ore is ground by adding water to form a slurry, a certain amount of sodium citrate is added to make the slurry alkaline. Sodium citrate hydrolyzes and ionizes to release a certain amount of hydroxide ions. Hydroxide ions can promote the breaking of Si-O-Si bonds in silicates, thereby promoting the dissolution of silicates and clays in gold ore, which is beneficial for fully exposing the encapsulated gold particles during grinding. On the other hand, sodium ions introduced by sodium citrate can also form ionic bonds with oxygen and break Si-O-Si bonds, thereby promoting the dissolution of silicates and clays in gold ore.

[0018] 2. The present invention uses butyl xanthate, lactic acid and sodium hexametaphosphate to prepare a flotation agent. Butyl xanthate can be used to capture gold-bearing minerals to obtain rough ore and remove silicates and clays from the gold ore. The added lactic acid can effectively inhibit the flotation of silicates and clays, so that silicates and clays are effectively separated from the rough ore. The added sodium hexametaphosphate can promote the dispersion of butyl xanthate and lactic acid and improve the flotation efficiency.

[0019] 3. In this invention, after adding water to the roughing ore to form a slurry, the pH of the slurry is first adjusted with ammonia water, and then a composite pretreatment agent is added. The composite pretreatment agent is obtained by uniformly mixing sodium persulfate, methyl isobutyl methanol (which has a foaming effect), and lower alcohols in the presence of sodium dodecyl sulfate and water. During the pretreatment of the roughing ore slurry, the reaction of methyl isobutyl methanol and lower alcohols generates uniform bubbles that adsorb mineral particles. At the same time, it can promote the dispersion of sodium persulfate in the slurry, which is beneficial for sodium persulfate to contact with mineral particles and oxidize sulfides and other substances that encapsulate gold particles, thereby promoting the subsequent leaching of gold.

[0020] 4. This invention uses a mixture of thiourea, sodium bicarbonate, and mineral salts at high temperature to prepare a composite gold extraction agent that can replace sodium cyanide. Moreover, it has the characteristic of low toxicity. At the same time, this invention also adds a dispersant obtained by dodecyl dimethyl betaine and butanediol or ethylene glycol during the gold leaching process to promote the dispersion of the composite gold extraction agent in the slurry, which is beneficial to its binding with gold particles and improves the gold leaching efficiency.

[0021] 5. The process of this invention is simple, easy to operate, and highly controllable, making it suitable for large-scale and automated production. Moreover, the process uses low-toxicity and harmless agents, reducing harm to the environment and people. Implementation

[0022] The present invention is further illustrated by the following examples, but these are not intended to limit the invention. Specific experimental conditions and methods not specified in the following examples are generally conventional methods well known to those skilled in the art.

[0023] Example 1: A low-toxicity and environmentally friendly gold ore beneficiation method, comprising the following steps:

[0024] (1) Gold ore is mixed with water to obtain slurry A, the solid-liquid ratio of slurry A is 1g:4mL, sodium citrate is added to slurry A and mixed for 25min under stirring at a speed of 550r / min to obtain slurry B, the mass ratio of slurry A to sodium citrate is 100:0.08, and then slurry B is ground to obtain slurry C, the particle size of more than 90% of the mineral powder particles in slurry C is 50-60μm;

[0025] (2) Add flotation agent to the slurry C obtained in step (1) to obtain rougher ore by flotation. The mass ratio of slurry C to flotation agent is 100:0.13. The flotation agent includes the following components in parts by weight: 4 parts butyl xanthate, 18 parts lactic acid, and 0.3 parts sodium hexametaphosphate.

[0026] (3) The rough ore obtained in step (2) is mixed with water to obtain slurry D. The solid-liquid ratio of slurry D is 1g:6mL. Slurry D is first ground so that more than 90% of the mineral powder particles in slurry D have a particle size of 10-20μm. Then, ammonia water is added to slurry D to adjust the pH value to 7.8. Then, a pretreatment agent is added to slurry D and treated for 20min under stirring at a speed of 200r / min. Then, the ore is filtered to obtain the refined ore. The mass ratio of slurry D to pretreatment agent is 100:0.025. The pretreatment agent includes the following components in parts by weight: 2.2 parts of sodium persulfate, 3.5 parts of methyl isobutyl methanol, 3.5 parts of lower alcohol, 2.5 parts of sodium dodecyl sulfate, and 32 parts of water. The lower alcohol is propylene glycol.

[0027] (4) Add water to the selected ore obtained in step (3) to make slurry E. The solid-liquid ratio of slurry E is 1g:3..5mL. Then add leaching agent and dispersant to slurry E and stir to leach for 4h. Then filter to obtain leachate. Use displacement method to obtain gold mud from leachate. The mass ratio of slurry E to leaching agent is 1000:0.4. The leaching agent includes the following raw materials in parts by weight: 30 parts of thiourea, 18 parts of sodium bicarbonate, and 4 parts of mineral salt. The specific preparation method of the leaching agent is to first mix thiourea, sodium bicarbonate and mineral salt and react at 150℃ for 25min, and then react at 600℃ for 40min to obtain leaching agent. The mass ratio of dispersant to leaching agent is 1:2.2. The dispersant includes the following components in parts by weight: 14 parts of dodecyl dimethyl betaine and 6 parts of ethylene glycol.

[0028] Example 2: A low-toxicity and environmentally friendly gold beneficiation method, comprising the following steps:

[0029] (1) Gold ore is mixed with water to obtain slurry A, the solid-liquid ratio of which is 1g:3mL. Sodium citrate is added to slurry A and mixed for 20min under stirring at a speed of 500r / min to obtain slurry B. The mass ratio of slurry A to sodium citrate is 100:0.05. Then, slurry B is ground to obtain slurry C. More than 90% of the mineral powder particles in slurry C have a particle size of 50-60μm.

[0030] (2) Add flotation agent to the slurry C obtained in step (1) to obtain rougher ore by flotation. The mass ratio of slurry C to flotation agent is 100:0.1. The flotation agent includes the following components in parts by weight: 1 part butyl xanthate, 10 parts lactic acid, and 0.2 parts sodium hexametaphosphate.

[0031] (3) The rough ore obtained in step (2) is mixed with water to obtain slurry D. The solid-liquid ratio of slurry D is 1g:5mL. Slurry D is first ground so that more than 90% of the mineral powder particles in slurry D have a particle size of 10-20μm. Then, ammonia water is added to slurry D to adjust the pH value to 7.5. Then, a pretreatment agent is added to slurry D and treated for 20min under stirring at a speed of 200r / min. Then, the ore is filtered to obtain the refined ore. The mass ratio of slurry D to pretreatment agent is 100:0.02. The pretreatment agent includes the following components in parts by weight: 1 part sodium persulfate, 3 parts methyl isobutyl methanol, 3 parts lower alcohol, 1 part sodium dodecyl sulfate, and 30 parts water. The lower alcohol is butanediol.

[0032] (4) Add water to the selected ore obtained in step (3) to make slurry E. The solid-liquid ratio of slurry E is 1g:3mL. Then add leaching agent and dispersant to slurry E and stir to leach for 3h. Then filter to obtain leachate. Use displacement method to obtain gold mud from leachate. The mass ratio of slurry E to leaching agent is 1000:0.2. The leaching agent includes the following raw materials in parts by weight: 20 parts thiourea, 10 parts sodium bicarbonate, and 1 part mineral salt. The specific preparation method of the leaching agent is to first mix thiourea, sodium bicarbonate and mineral salt and react at 100℃ for 20min, and then react at 500℃ for 30min to obtain leaching agent. The mass ratio of dispersant to leaching agent is 1:2. The dispersant includes the following components in parts by weight: 10 parts dodecyl dimethyl betaine and 5 parts butanediol.

[0033] Example 3: A low-toxicity and environmentally friendly gold beneficiation method, comprising the following steps:

[0034] (1) Gold ore is mixed with water to obtain slurry A, the solid-liquid ratio of which is 1g:4.5mL. Sodium citrate is added to slurry A and mixed for 25min under stirring at a speed of 550r / min to obtain slurry B. The mass ratio of slurry A to sodium citrate is 100:0.07. Then, slurry B is ground to obtain slurry C. More than 90% of the mineral powder particles in slurry C have a particle size of 60-80μm.

[0035] (2) Add flotation agent to the slurry C obtained in step (1) to obtain rougher ore by flotation. The mass ratio of slurry C to flotation agent is 100:0.15. The flotation agent includes the following components in parts by weight: 2 parts butyl xanthate, 15 parts lactic acid, and 0.4 parts sodium hexametaphosphate.

[0036] (3) The rough ore obtained in step (2) is mixed with water to obtain slurry D. The solid-liquid ratio of slurry D is 1g:7mL. Slurry D is first ground so that more than 90% of the mineral powder particles in slurry D have a particle size of 10-20μm. Then, ammonia water is added to slurry D to adjust the pH value to 8.0. Then, a pretreatment agent is added to slurry D and treated for 25min under stirring at a speed of 250r / min. Then, the ore is filtered to obtain the refined ore. The mass ratio of slurry D to pretreatment agent is 100:0.028. The pretreatment agent includes the following components in parts by weight: 2 parts sodium persulfate, 4 parts methyl isobutyl methanol, 4 parts lower alcohol, 2.8 parts sodium dodecyl sulfate, and 35 parts water. The lower alcohol is propylene glycol.

[0037] (4) Add water to the selected ore obtained in step (3) to make slurry E. The solid-liquid ratio of slurry E is 1g:4.5mL. Then add leaching agent and dispersant to slurry E and stir to leach for 4h. Then filter to obtain leachate. Use displacement method to obtain gold mud from leachate. The mass ratio of slurry E to leaching agent is 1000:0.3. The leaching agent includes the following raw materials in parts by weight: 30 parts of thiourea, 15 parts of sodium bicarbonate, and 2 parts of mineral salt. The specific preparation method of the leaching agent is to first mix thiourea, sodium bicarbonate and mineral salt and react at 180℃ for 30min, and then react at 600℃ for 35min to obtain leaching agent. The mass ratio of dispersant to leaching agent is 1:2.2. The dispersant includes the following components in parts by weight: 15 parts of dodecyl dimethyl betaine and 7 parts of ethylene glycol.

[0038] Example 4: A low-toxicity and environmentally friendly gold beneficiation method, comprising the following steps:

[0039] (1) Gold ore is mixed with water to obtain slurry A, the solid-liquid ratio of which is 1g:5mL. Sodium citrate is added to slurry A and mixed for 30min under stirring at a speed of 600r / min to obtain slurry B. The mass ratio of slurry A to sodium citrate is 100:0.1. Then, slurry B is ground to obtain slurry C. More than 90% of the mineral powder particles in slurry C have a particle size of 80-100μm.

[0040] (2) Add flotation agent to the slurry C obtained in step (1) to obtain rougher ore by flotation. The mass ratio of slurry C to flotation agent is 100:0.2. The flotation agent includes the following components in parts by weight: 5 parts butyl xanthate, 20 parts lactic acid, and 0.5 parts sodium hexametaphosphate.

[0041] (3) The rough ore obtained in step (2) is mixed with water to obtain slurry D. The solid-liquid ratio of slurry D is 1g:8mL. Slurry D is first ground so that more than 90% of the mineral powder particles in slurry D have a particle size of 10-20μm. Then, ammonia water is added to slurry D to adjust the pH value to 8.5. Then, a pretreatment agent is added to slurry D and the mixture is treated for 30min under stirring at a speed of 300r / min. Then, the ore is filtered to obtain the refined ore. The mass ratio of slurry D to pretreatment agent is 100:0.03. The pretreatment agent includes the following components in parts by weight: 3 parts sodium persulfate, 5 parts methyl isobutyl methanol, 5 parts lower alcohol, 3 parts sodium dodecyl sulfate, and 40 parts water. The lower alcohol is butanediol.

[0042] (4) Add water to the selected ore obtained in step (3) to make slurry E. The solid-liquid ratio of slurry E is 1g:5mL. Then add leaching agent and dispersant to slurry E and stir to leach for 5h. Then filter to obtain leachate. Use displacement method to obtain gold mud from leachate. The mass ratio of slurry E to leaching agent is 1000:0.5. The leaching agent includes the following raw materials in parts by weight: 40 parts of thiourea, 20 parts of sodium bicarbonate, and 5 parts of mineral salt. The specific preparation method of the leaching agent is to first mix thiourea, sodium bicarbonate and mineral salt and react at 200℃ for 30min, and then react at 700℃ for 45min to obtain leaching agent. The mass ratio of dispersant to leaching agent is 1:2. The dispersant includes the following components in parts by weight: 20 parts of dodecyl dimethyl betaine and 8 parts of butanediol.

[0043] Example 5: A low-toxicity and environmentally friendly gold beneficiation method, comprising the following steps:

[0044] (1) Gold ore is mixed with water to obtain slurry A, the solid-liquid ratio of which is 1g:3.5mL. Sodium citrate is added to slurry A and mixed for 30min under stirring at a speed of 600r / min to obtain slurry B. The mass ratio of slurry A to sodium citrate is 100:0.09. Then, slurry B is ground to obtain slurry C. More than 90% of the mineral powder particles in slurry C have a particle size of 80-100μm.

[0045] (2) Add flotation agent to the slurry C obtained in step (1) to obtain rougher ore by flotation. The mass ratio of slurry C to flotation agent is 100:0.18. The flotation agent includes the following components in parts by weight: 3 parts butyl xanthate, 120 parts lactic acid, and 0.25 parts sodium hexametaphosphate.

[0046] (3) The rough ore obtained in step (2) is mixed with water to obtain slurry D. The solid-liquid ratio of slurry D is 1g:6.5mL. Slurry D is first ground so that more than 90% of the mineral powder particles in slurry D have a particle size of 10-20μm. Then, ammonia water is added to slurry D to adjust the pH value to 8.0. Then, a pretreatment agent is added to slurry D and treated for 30min under stirring at a speed of 300r / min. Then, the ore is filtered to obtain the refined ore. The mass ratio of slurry D to pretreatment agent is 100:0.025. The pretreatment agent includes the following components in parts by weight: 2.5 parts sodium persulfate, 4.5 parts methyl isobutyl methanol, 4.5 parts lower alcohol, 2.6 parts sodium dodecyl sulfate, and 38 parts water. The lower alcohol is propylene glycol.

[0047] (4) Add water to the selected ore obtained in step (3) to make slurry E. The solid-liquid ratio of slurry E is 1g:4mL. Then add leaching agent and dispersant to slurry E and stir to leach for 3h. Then filter to obtain leachate. Use displacement method to obtain gold mud from leachate. The mass ratio of slurry E to leaching agent is 1000:0.45. The leaching agent includes the following raw materials in parts by weight: 25 parts thiourea, 14 parts sodium bicarbonate, and 3.5 parts mineral salt. The specific preparation method of the leaching agent is to first mix thiourea, sodium bicarbonate and mineral salt and react at 160℃ for 25min, and then react at 550℃ for 30min to obtain leaching agent. The mass ratio of dispersant to leaching agent is 1:2.6. The dispersant includes the following components in parts by weight: 18 parts dodecyl dimethyl betaine and 7 parts ethylene glycol.

[0048] Comparative Example 1: The difference between the low-toxicity and environmentally friendly gold beneficiation method described in this comparative example and the method described in Example 1 is that in step (1), sodium citrate is not added to slurry A, but slurry A is directly ground to obtain slurry C.

[0049] Comparative Example 2: The difference between the low-toxicity and environmentally friendly gold beneficiation method described in this comparative example and the method described in Example 1 is that, in step (2), the flotation agent does not contain lactic acid components.

[0050] Comparative Example 3: The difference between the low-toxicity and environmentally friendly gold beneficiation method described in this comparative example and the method described in Example 1 is that the pretreatment agent in step (3) does not contain methyl isobutyl methanol.

[0051] Comparative Example 4: The difference between the low-toxicity and environmentally friendly gold beneficiation method described in this comparative example and the method described in Example 1 is that the dispersant in step (4) does not contain dodecyl dimethyl betaine.

[0052] Comparative Example 5: The difference between the low-toxicity and environmentally friendly gold beneficiation method described in this comparative example and the method described in Example 1 is that the dispersant in step (4) does not contain ethylene glycol.

[0053] Experimental Example: The same batch of gold ore was evenly divided into 10 portions, and then processed according to the methods described in Examples 1-5 and Comparative Examples 1-5 respectively. The gold leaching rate of the method was calculated based on the gold content in the gold ore and the gold content in the slag obtained, i.e., gold leaching rate = (gold ore mass × gold content in gold ore - slag mass × gold content in slag) / (gold ore mass × gold content in gold ore) × 100%. The specific results are shown in Table 1.

[0054] Table 1 Gold leaching rates obtained by different treatment methods

[0055]

[0056] As can be seen from the above data, the method of the present invention can achieve excellent gold leaching rates. However, in Comparative Example 1, the absence of sodium citrate treatment makes it difficult to dissolve silicates and other substances, increasing the difficulty of exposing the encapsulated gold particles and thus affecting the gold leaching rate. In Comparative Example 2, the absence of lactic acid components means that some silicate substances remain mixed with the rough ore, and during the leaching process, silicates adsorb gold particles, affecting the gold leaching rate. In Comparative Example 3, the absence of methyl isobutyl methanol components affects the stable generation of bubbles, reducing the pretreatment effect and thus affecting the gold leaching rate. Comparative Examples 4 and 5 used only dodecyl dimethyl betaine or ethylene glycol, which could not achieve the effect of the composite dispersant of the present invention.

[0057] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A low-toxicity and environmentally friendly gold beneficiation method, characterized in that: Includes the following steps: (1) Gold ore is mixed with water to obtain slurry A, the solid-liquid ratio of slurry A is 1g: (3-5)mL, sodium citrate is added to slurry A and stirred for 20-30min to obtain slurry B, the mass ratio of slurry A to sodium citrate is 100: (0.05-0.1), and then slurry B is ground to obtain slurry C, the particle size of more than 90% of the mineral powder particles in slurry C is 50-100μm; (2) Add flotation agent to the slurry C obtained in step (1) to obtain rougher ore by flotation. The mass ratio of slurry C to flotation agent is 100:(0.1~0.2). The flotation agent includes the following components in parts by weight: 1~5 parts butyl xanthate, 10~20 parts lactic acid, and 0.2~0.5 parts sodium hexametaphosphate. (3) Add water to the rough ore obtained in step (2) to make slurry D. The solid-liquid ratio of slurry D is 1g: (5-8)mL. Then add ammonia water to slurry D to adjust the pH value to 7.5-8.

5. Then add pretreatment agent to slurry D and stir for 20-30min. Then filter to obtain fine ore. The mass ratio of slurry D to pretreatment agent is 100: (0.02-0.03). The pretreatment agent includes the following components in parts by weight: 1-3 parts sodium persulfate, 3-5 parts methyl isobutyl methanol, 3-5 parts lower alcohol, 1-3 parts sodium dodecyl sulfate, and 30-40 parts water. (4) Add water to the selected ore obtained in step (3) to make slurry E. The solid-liquid ratio of slurry E is 1g:(3-5)mL. Then add leaching agent to slurry E and stir to leach for 3-5h. Then filter to obtain leachate. Use displacement method to obtain gold mud from leachate. The mass ratio of slurry E to leaching agent is 1000:(0.2-0.5). The leaching agent includes the following raw materials in parts by weight: 20-40 parts of thiourea, 10-20 parts of sodium bicarbonate, and 1-5 parts of mineral salt. The leaching agent is obtained by mixing the raw material components and reacting them at high temperature.

2. The low-toxicity and environmentally friendly gold beneficiation method according to claim 1, characterized in that: In step (1), sodium citrate is added to slurry A and mixed for 20 to 30 minutes under stirring conditions of 500 to 600 r / min to obtain slurry B.

3. The low-toxicity and environmentally friendly gold ore beneficiation method according to claim 1, characterized in that: In step (3), the slurry D is first ground so that more than 90% of the mineral powder particles in the slurry D have a particle size of 10-20 μm. Then, ammonia water and pretreatment agent are added in sequence for further treatment.

4. The low-toxicity and environmentally friendly gold ore beneficiation method according to claim 1, characterized in that: In step (3), a pretreatment agent is added to slurry D and treated for 20 to 30 minutes under stirring conditions at a speed of 200 to 300 r / min.

5. The low-toxicity and environmentally friendly gold ore beneficiation method according to claim 1, characterized in that: The lower alcohol mentioned in step (3) is either propylene glycol or butanediol.

6. The low-toxicity and environmentally friendly gold ore beneficiation method according to claim 1, characterized in that: In step (4), an extractant and a dispersant are added to slurry E and stirred for 3-5 hours. The mass ratio of the dispersant to the extractant is 1:(2-3). The dispersant includes the following components in parts by weight: 10-20 parts of dodecyl dimethyl betaine and 5-8 parts of butanediol or ethylene glycol.

7. The low-toxicity and environmentally friendly gold ore beneficiation method according to claim 1, characterized in that: In step (4), the specific method for preparing the leaching agent is to first mix thiourea, sodium bicarbonate and mineral salt and react them at 100-200℃ for 20-30 min, and then react them at 500-700℃ for 30-45 min to obtain the leaching agent.

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