Gold leaching agent and gold leaching process for treating high-carbon gold-bearing minerals

Abstract

The invention provides a gold leaching agent for treating high-carbon gold-bearing minerals and a gold leaching process, and belongs to the technical field of hydrometallurgy. According to the gold leaching agent, guanidinium thiocyanate is used as an agent main body, a hydroximic acid compound is used as a complexing synergist, and soluble inorganic salt of ferric iron is used as a competitive adsorbent. In a leaching system, guanidine thiocyanate can be decomposed to generate guanidine, sodium sulfide, sodium thiocyanate and water. Thiourea anions are converted into cyanamide under the alkaline condition, then cyanamide is slowly released and decomposed into cyanide ions, the cyanide ions are complexed with gold ions, and gold leaching is achieved. Namely, guanidinium thiocyanate has the effect of releasing the cyanide ions step by step, and slow release of the cyanide ions is realized. The gold leaching agent system does not contain cyanide (sodium cyanide, potassium cyanide and the like) and is a clean and environment-friendly agent system, and efficient leaching of gold in high-carbon gold-bearing minerals can be achieved through the synergistic effect of all functional agent components.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a gold leaching agent and a gold leaching process for treating high-carbon gold-containing minerals. Background Art

[0002] In the gold industry, difficult-to-process gold-bearing ore resources have become the focus of the future gold industry. Gold-bearing minerals with a carbon content higher than 0.2% are classified as high-carbon gold-bearing minerals. The traditional cyanide gold leaching process is difficult to apply to high-carbon gold-bearing minerals. The main reason is that the amorphous carbon in the carbonaceous material in the ore has a structure similar to activated carbon, which can adsorb gold that has been dissolved by cyanide, resulting in a low gold leaching rate. This phenomenon is also called "gold robbery". In order to increase the leaching rate of gold in high-carbon gold-bearing minerals, it is necessary to pre-treat them by roasting the carbonaceous minerals at high temperatures to oxidize and decompose them, thereby weakening their ability to adsorb gold ions. This method has a short processing time and obvious effects, but it is necessary to pay attention to controlling the roasting temperature to prevent secondary loss of gold and the generation of harmful gases. In the production process, the energy consumption is huge and it is difficult to promote universally.

[0003] In order to achieve efficient gold extraction from high-carbon gold-bearing minerals, gold extraction reagent systems and processes such as the thiosulfate method and the halogen method have emerged. However, the thiosulfate method has problems such as large thiosulfate consumption, easy environmental pollution caused by ammonia water, and difficulty in recovering gold from the leaching solution.

[0004] In view of this, it is necessary to design a gold leaching agent and a gold leaching process for treating high-carbon gold-containing minerals to solve the above problems. Summary of the invention

[0005] The purpose of the present application is to provide a gold leaching agent and a gold leaching process for treating high-carbon gold-containing minerals, wherein the gold leaching agent uses guanidine thiocyanate as the agent body, hydroxamic acid compounds as the complexing synergist, and soluble inorganic salts of trivalent iron as the competitive adsorbent. The gold leaching agent system does not contain cyanide (sodium cyanide, potassium cyanide, etc.), and is a clean and environmentally friendly agent system. Through the synergistic effect of various functional agent components, efficient leaching of gold in high-carbon gold-containing minerals can be achieved.

[0006] An embodiment of the present application provides a gold leaching agent for treating high-carbon gold-containing minerals, including an agent body, a complexing enhancer and a competitive adsorbent; the agent body is guanidine thiocyanate, the complexing enhancer is a hydroxamic acid compound, and the competitive adsorbent is a soluble inorganic salt of trivalent iron.

[0007] In the technical scheme of the embodiment of the present application, guanidine thiocyanate is used as the main body of the agent, hydroxamic acid compounds are used as the complexing synergist, and soluble inorganic salts of trivalent iron are used as competitive adsorbents. Under alkaline conditions, guanidine thiocyanate will decompose to produce guanidine, sodium sulfide, sodium thiocyanate and water. Thiourea anion is converted into cyanamide under alkaline conditions, and then cyanamide is slowly released and decomposed into cyanide ions, which are complexed with gold ions to achieve gold leaching. That is, guanidine thiocyanate has the effect of releasing cyanide ions in steps, and cyanide ions are slowly released. The gold leaching agent system does not contain cyanide (sodium cyanide, potassium cyanide, etc.), is a clean, environmentally friendly agent system, and through the synergistic effect of each functional agent component, it is possible to achieve efficient leaching of gold in high-carbon gold-containing minerals.

[0008] In some embodiments, in the gold leaching agent for treating high-carbon gold-containing minerals, the mass concentration of guanidine thiocyanate is 20-50 g / L, the mass concentration of the complexing enhancer is 0.5-5 g / L, and the mass concentration of the competitive adsorbent is 0.25-2.5 g / L.

[0009] In some embodiments, the hydroxamate compound is one or more of octyl hydroxamic acid sodium salt, sodium hydroxamate, and sodium benzohydroxamate hydrate.

[0010] In some embodiments, the soluble inorganic salt of trivalent iron is one or more of ferric nitrate, ferric sulfate, and ferric hydrochloride.

[0011] In some embodiments, the gold leaching agent system for treating high-carbon gold-containing minerals is used in an environment with a pH of ≥7.

[0012] The embodiment of the present application also provides a gold leaching process, which uses the aforementioned gold leaching agent for treating high-carbon gold-containing minerals to leaching gold, including the following steps:

[0013] S1, crushing the high-carbon gold-containing ore material to a particle size of -0.074 mm, wherein the ore powder accounts for 75% to 85% of the total mass of the material, and adding water to adjust the slurry to a mass percentage concentration of 30% to 35%;

[0014] S2, adding the reagent body, the complexing enhancer and the competitive adsorbent to the slurry prepared in step S1, adjusting the pH value of the slurry to keep it at pH ≥ 7, stirring and leaching for 12-24 hours at normal temperature and pressure to obtain gold-containing precious liquid and gold leaching tailings.

[0015] In the technical solution of the embodiment of the present application, gold is leached using a gold leaching agent for treating high-carbon gold-containing minerals. In an alkaline environment, the reaction process is as follows:

[0016] 2GuSCN+3NaOH=2Gu+Na2S+2NaSCN+H2O

[0017] Among them, GuSCN represents guanidine thiocyanate, Gu represents guanidine, NaOH represents sodium hydroxide (base), Na2S represents sodium sulfide, and NaSCN represents sodium thiocyanate.

[0018] That is, in the leaching system, guanidine thiocyanate decomposes to produce guanidine, sodium sulfide, sodium thiocyanate and water.

[0019] The thiourea anion is converted to cyanamide under alkaline conditions:

[0020] SCN - →NH2CH

[0021] Subsequently, cyanamide slowly decomposes into cyanide ions, which complex with gold ions to achieve gold leaching.

[0022] That is, guanidine thiocyanate has the effect of releasing cyanide ions in steps, achieving the sustained release of cyanide ions.

[0023] In the process of leaching gold using the gold leaching agent for treating high-carbon gold-containing minerals of the present invention, soluble trivalent iron ions are used as oxidants to increase the gold valence state, which is conducive to the conversion into gold ions, while the trivalent iron is reduced to divalent iron. The free iron (III) ions react with hydroxamate compounds to form chelates.

[0024] For example, when the hydroxamate compound is sodium octylhydroxamate, the molecular structure of the generated chelate A is shown below. There is a significant difference in the electrostatic potential between iron (III)-hydroxamate chelates and gold-cyanide complexes, resulting in the electrostatic adsorption of iron (III)-hydroxamate chelates to carbonaceous materials in high-carbon gold-bearing minerals being better than the electrostatic adsorption of gold-cyanide complexes to carbonaceous materials in high-carbon gold-bearing minerals. When iron (III)-hydroxamate chelates and gold-cyanide complexes exist in the system at the same time, the carbonaceous materials in the gold-bearing minerals preferentially electrostatically adsorb iron (III)-hydroxamate chelates. When the electrochemical sites on the carbonaceous surface are saturated, they no longer electrostatically adsorb to the gold-cyanide complex, and ultimately the gold-cyanide complex is completely in the liquid phase, thereby ensuring the gold leaching rate.

[0025]

[0026] In some embodiments, in step S1, the high-carbon gold-containing mineral material includes one or more of bio-oxidation slag, bio-oxidation heap leaching slag, roasted sand, and flotation gold concentrate.

[0027] In some embodiments, in step S2, sodium hydroxide is used to adjust the pH value of the slurry.

[0028] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. DETAILED DESCRIPTION

[0029] The following is a detailed description of the embodiments of the technical solution of the present application. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the description and claims of this application and any variations thereof are intended to cover non-exclusive inclusions.

[0031] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0032] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0033] The traditional cyanide gold leaching process is difficult to apply to high-carbon gold-bearing minerals. In order to improve the leaching rate of gold in high-carbon gold-bearing minerals, it is necessary to pre-treat them by roasting the carbonaceous minerals at high temperatures to oxidize and decompose them, thereby weakening their ability to adsorb gold ions. This method has a short processing time and obvious effects, but it is necessary to pay attention to controlling the roasting temperature to prevent secondary loss of gold and the generation of harmful gases. In the production process, the energy consumption is huge and it is difficult to promote universally.

[0034] The present invention provides a gold leaching agent for treating high-carbon gold-containing minerals, comprising an agent body, a complexing synergist and a competitive adsorbent. The agent body is guanidine thiocyanate, the complexing synergist is a hydroxamic acid compound, and the competitive adsorbent is a soluble inorganic salt of trivalent iron. The hydroxamic acid salt compound is one or more of octyl hydroxamic acid sodium salt, sodium hydroxamic acid, and sodium benzohydroxamic acid hydrate.

[0035] The soluble inorganic salt of trivalent iron is one or more of ferric nitrate, ferric sulfate and ferric hydrochloride.

[0036] In the gold leaching agent for treating high-carbon gold-bearing minerals, the mass concentration of guanidine thiocyanate is 20-50 g / L, the mass concentration of the complexing enhancer is 0.5-5 g / L, and the mass concentration of the competitive adsorbent is 0.25-2.5 g / L.

[0037] In an alkaline environment, guanidine thiocyanate in the gold leaching agent system will decompose to produce guanidine, sodium sulfide, sodium thiocyanate and water. Thiourea anions are converted into cyanamide under alkaline conditions, and then cyanamide is slowly decomposed into cyanide ions, which are complexed with gold ions to achieve gold leaching. That is, guanidine thiocyanate has the effect of releasing cyanide ions in steps, achieving a slow release of cyanide ions.

[0038] The gold leaching reagent system does not contain cyanide (sodium cyanide, potassium cyanide, etc.) and is a clean and environmentally friendly reagent system. Through the synergistic effect of various functional reagent components, efficient leaching of gold in high-carbon gold-containing minerals can be achieved.

[0039] The present invention also provides a gold leaching process, which uses the above-mentioned gold leaching agent for treating high-carbon gold-containing minerals to leaching gold, comprising the following steps:

[0040] S1, crushing the high-carbon gold-containing ore material to a particle size of -0.074 mm, wherein the ore powder accounts for 75% to 85% of the total mass of the material, and adding water to adjust the slurry to a mass percentage concentration of 30% to 35%;

[0041] S2, adding the reagent body, the complexing enhancer and the competitive adsorbent to the slurry prepared in step S1, adjusting the pH value of the slurry to keep it at pH ≥ 7, stirring and leaching for 12-24 hours at normal temperature and pressure to obtain gold-containing precious liquid and gold leaching tailings.

[0042] In step S1, the high-carbon gold-containing mineral material includes one or more of bio-oxidation slag, bio-oxidation heap leaching slag, roasted sand, and flotation gold concentrate.

[0043] In step S2, sodium hydroxide is used to adjust the pH value of the slurry.

[0044] The present invention realizes the slow-release cyanide extraction of gold from high-carbon gold-containing minerals by designing the components of the gold leaching agent and utilizing the synergistic effect of the components in the system, so as to solve the technical bottleneck in the gold field and achieve a balance between economy and environment.

[0045] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0046] Example 1

[0047] This embodiment provides a gold leaching process, which uses a clean gold leaching agent system for treating gold-containing minerals to leaching gold, including the following steps:

[0048] The high-carbon gold-bearing minerals used in the test have multi-element contents as shown in Table 1 below:

[0049] Table 1 Results of multi-element analysis of raw ore

[0050]

[0051]

[0052] S1, slurry preparation: take 500g of high-carbon gold-containing ore, add water and ball mill for 25min, crush the ore powder to a particle size of -0.074mm, which accounts for 80% of the total mass of the material, pour the ball-milled ore powder into a stirring tank, add water under mechanical stirring to adjust the slurry concentration to 30%;

[0053] S2, adding the reagent body (guanidine thiocyanate), the complexing enhancer (octyl hydroxamic acid sodium salt) and the competitive adsorbent (ferric nitrate) to the slurry prepared in step S1; the pH potentiometer shows that the pH of the slurry is 9.0-10.0, stirring and leaching for 24 hours at normal temperature and pressure to obtain gold-containing precious liquid and gold leaching tailings; wherein, the concentration of guanidine thiocyanate is 30 g / L, the concentration of the complexing enhancer octyl hydroxamic acid sodium salt is 1 g / L, and the concentration of the competitive adsorbent ferric nitrate is 2 g / L.

[0054] Comparative Example 1

[0055] Comparative Example 1: The conventional cyanide leaching process is used to leach gold from high carbon gold-bearing minerals, and the steps are as follows:

[0056] The high-carbon gold-containing mineral used in the comparative example 1 test is the same as the high-carbon gold-containing mineral used in example 1.

[0057] S1. Preparation of ore pulp: Take 500g of high-carbon gold-containing ore material, add water and ball mill for 25min, crush it to the ore powder with a particle size of -0.074mm accounting for 80% of the total mass of the material, pour the ball-milled ore powder into a stirring tank, add water under mechanical stirring to adjust the ore pulp concentration to 30%;

[0058] S2. Add sodium cyanide to the slurry prepared in step S1. The pH potentiometer shows that the pH of the slurry is 9.0-10.0. Stir and leach for 24 hours at normal temperature and pressure to obtain gold-containing precious liquid and gold leaching tailings; wherein, the sodium cyanide is 5 g / L (sufficient amount).

[0059] The gold leaching rates of Example 1 and Comparative Example 1 are shown in Table 2 below.

[0060] Table 2

[0061]

[0062]

[0063] It can be seen from the gold leaching rate shown in the above table that the gold leaching agent for high-carbon gold-bearing minerals is suitable for high-carbon gold-bearing minerals, while traditional cyanide leaching is difficult to apply to high-carbon gold-bearing mineral systems.

[0064] Comparative Example 2

[0065] Compared with Example 1, the difference is that in step S2, no complexing synergist is added, and the rest is substantially the same as Example 1, which will not be described again.

[0066] Comparative Example 3

[0067] Compared with Example 1, the difference is that in step S2, no competitive adsorbent is added, and the rest is substantially the same as Example 1, which will not be described again.

[0068] Table 3 Gold leaching rate of Example 1 and Comparative Examples 2-3

[0069] Gold leaching rate (%) Example 1 93 Comparative Example 2 72 Comparative Example 3 56

[0070] From the gold leaching rate shown in the table above, it can be seen that each reagent in the gold leaching reagent system for high-carbon gold-bearing minerals plays an important role and is indispensable. Without a complexing enhancer or a competitive adsorbent, it is impossible to achieve efficient leaching of gold in high-carbon gold-bearing minerals. When the reagent system is complete in variety and the dosage is reasonably matched, the reagents of each functional unit cooperate with each other for synergistic leaching to achieve efficient leaching of gold in high-carbon gold-bearing minerals.

[0071] It can be seen from Comparative Example 2 that when the complexing enhancer octyl hydroxamic acid sodium salt is not used, the chelating ligand required for the iron ions cannot be provided, and the iron (III)-hydroxamate chelate complex cannot preferentially electrostatically adsorb the carbon in the high-carbon gold-containing mineral, which affects the efficient leaching of gold.

[0072] It can be seen from Comparative Example 3 that when the competitive adsorbent ferric nitrate is not used, the chelating center ion required for the chelation of the complexing enhancer cannot be provided, and the iron (III)-hydroxamate chelate cannot preferentially electrostatically adsorb the carbon in the high-carbon gold-containing mineral, which affects the efficient leaching of gold.

[0073] Examples 2-3 and Comparative Examples 1-3

[0074] Compared with Example 1, the main difference is that the mass concentration of the main agent guanidine thiocyanate in step S2 is changed, and other experimental parameters and conditions are basically the same as those in Example 1, which will not be repeated here. The details are shown in the following table.

[0076]

[0077] The gold leaching rates of Examples 1-7 and Comparative Examples 4-10 are shown in the following table.

[0078]

[0079]

[0080] It can be seen from the above table that there is an optimal range for the dosage of each reagent in the gold leaching reagent system for high-carbon gold-bearing minerals. When the dosage is lower than this range, the gold leaching rate is low and the leaching effect is poor. When the dosage is higher than the value in the range, the leaching effect will no longer be significantly improved, and may even worsen the gold leaching effect.

[0081] For details, please refer to Examples 1, 6-7 and Comparative Examples 8-10. When the concentration of the competitive adsorbent ferric nitrate is ≤0.25 g / L, most of the Fe 3+ Completely converted to Fe 2+ , destroying the Fe 3+ , Fe 2+ The optimal equilibrium concentration of the leaching system E(Fe 3+ / Fe 2+ ) redox potential, the catalyst Fe 3+ The catalytic oxidation effect of the gold leaching reaction was deteriorated, which in turn affected the progress of the entire gold leaching reaction. At the same time, when the concentration of the competitive adsorbent ferric nitrate was ≥5g / L, the complexing enhancer in the leaching solution was completely consumed, and the free Fe 3+ The concentration is too high, a large amount of Fe 3+Under alkaline conditions, it is converted into iron hydroxide precipitation, which adheres to the surface of the mineral and affects the subsequent gold leaching, resulting in a low gold leaching rate. Therefore, the optimal dosage of the reagent is obtained by combining the leaching effect and production cost. When the reagent components are within the optimal range, the maximum gold leaching effect can be exerted. The various reagents interact with each other for synergistic leaching, the gold leaching rate is high, the cost is low, and the economic benefits are high.

[0082] Experiments show that the complexing synergist is replaced by one or more of sodium hydroxamate and sodium benzohydroxamate hydrate. The soluble inorganic salt of trivalent iron is replaced by one or more of ferric sulfate and ferric hydrochloride.

[0083] The gold leaching rate can reach over 90%.

[0084] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A gold leaching agent for treating high-carbon gold-containing minerals, characterized in that: It comprises a drug body, a complexing enhancer and a competitive adsorbent; the drug body is guanidine thiocyanate, the complexing enhancer is a hydroxamic acid compound, and the competitive adsorbent is a soluble inorganic salt of trivalent iron.

2. The gold leaching agent for treating high-carbon gold-containing minerals according to claim 1, characterized in that: In the gold leaching agent for treating high-carbon gold-containing minerals, the mass concentration of the guanidine thiocyanate is 20-50 g / L, the mass concentration of the complexing enhancer is 0.5-5 g / L, and the mass concentration of the competitive adsorbent is 0.25-2.5 g / L.

3. The gold leaching agent for treating high-carbon gold-containing minerals according to claim 1, characterized in that: The hydroxamate compound is one or more of octyl hydroxamic acid sodium salt, sodium hydroxamate, and sodium benzohydroxamic acid hydrate.

4. The gold leaching agent for treating high-carbon gold-containing minerals according to claim 1, characterized in that: The soluble inorganic salt of trivalent iron is one or more of ferric nitrate, ferric sulfate and ferric hydrochloride.

5. The gold leaching agent for treating high-carbon gold-containing minerals according to claim 1, characterized in that: The use environment of the gold leaching agent system for treating high-carbon gold-containing minerals is pH ≥ 7.

6. A gold immersion process, characterized in that: The gold leaching agent for treating high-carbon gold-containing minerals according to any one of claims 1 to 5 is used for gold leaching, comprising the following steps: S1, crushing the high-carbon gold-containing ore material to a particle size of -0.074 mm, wherein the ore powder accounts for 75% to 85% of the total mass of the material, and adding water to adjust the slurry to a mass percentage concentration of 30% to 35%; S2, adding the reagent body, the complexing enhancer and the competitive adsorbent to the slurry prepared in step S1, adjusting the pH value of the slurry to keep it at pH ≥ 7, stirring and leaching for 12-24 hours at normal temperature and pressure to obtain gold-containing precious liquid and gold leaching tailings.

7. The immersion gold process according to claim 6, characterized in that: In step S1, the high-carbon gold-containing mineral material includes one or more of bio-oxidation slag, bio-oxidation heap leaching slag, roasted sand, and flotation gold concentrate.

8. The immersion gold process according to claim 6, characterized in that: In step S2, sodium hydroxide is used to adjust the pH value of the slurry.

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