In-situ self-excitation and enhanced gold leaching method for carlin type gold concentrate

Abstract

The invention discloses a carlin type gold concentrate in-situ self-excitation and enhanced gold leaching method which comprises the following steps: adding an oxidizing agent and an alkaline reagent into a carlin type gold concentrate ore pulp system in a continuous, slow and proper adding manner at normal temperature and normal pressure, maintaining the oxidation potential of the ore pulp system to be-600 to-15.3 mV and the pH value to be 7 to 11, and carrying out in-situ self-excitation and enhanced gold leaching on the carlin type gold concentrate; and gold-loaded sulfide minerals in the gold concentrate are subjected to in-situ oxidation in a leaching system to generate stable thiosulfate as a gold leaching agent, so that in-situ self-excitation and enhanced gold leaching of the Carlin type gold concentrate are realized. According to the method, thiosulfate is formed through in-situ self-excitation, meanwhile, gold is extracted through in-situ complexing, consumption of external thiosulfate is reduced, pretreatment is not needed in the gold leaching process, the technology is simpler, the production cost is lower, the good gold extraction rate is guaranteed, meanwhile, no special requirement for equipment is needed, and the system is more controllable.

Description

Technical Field

[0001] The present invention belongs to the technical field of precious metal smelting and comprehensive utilization of Carlin-type gold ore resources, and particularly relates to a method for in-situ self-excitation and enhanced gold leaching of Carlin-type refined gold ore. Background Art

[0002] With the continuous exploitation and utilization of global gold ore resources, high-grade and easily beneficiated gold ore resources are increasingly depleted. At present, more than 60% of the gold reserves in the world are hosted in refractory gold ores, and this ratio is increasing year by year. Therefore, refractory gold ores with huge reserves are gradually becoming an important raw material in the gold production industry.

[0003] Carlin-type gold ore is a typical fine disseminated refractory gold ore, in which gold is mainly hosted in the gold-bearing sulfide minerals pyrite and arsenopyrite in microscopic and submicroscopic forms. Due to the encapsulation of gold, it is difficult to process and extract gold. With the rapid development of modern beneficiation technology, after treatment by technologies such as the combined process of gravity separation and flotation, the gold grade of Carlin-type refined gold ore has been significantly improved. At the same time, as a sulfur-containing gold ore, the sulfur element in it has also been enriched.

[0004] To realize the industrial utilization of Carlin-type gold ore, pretreatment technologies such as roasting oxidation method, pressure oxidation method, and biological oxidation method have emerged successively in the industry. These pretreatment technologies can oxidize and dissociate the gold-bearing sulfide minerals in Carlin-type gold ore, making the gold fully exposed and in good contact with cyanide, thereby improving the leaching rate and recovery rate of gold.

[0005] Among non-cyanide gold leaching methods, the thiosulfate method has the advantages of being non-toxic, short leaching cycle, and high gold recovery rate, which is more in line with the requirements of the green development of the current gold smelting industry. However, thiosulfate is extremely unstable and easily decomposes, resulting in excessive consumption of thiosulfate during the gold leaching process. Therefore, to achieve the industrial application of thiosulfate gold leaching, the high consumption of thiosulfate is an urgent technical bottleneck to be solved.

[0006] Chinese Patent with Publication No. CN112981130B discloses "a method for in-situ self-gold leaching of sulfide gold ore". It conducts roasting treatment on sulfide gold ore powder in an inert atmosphere at 450 - 800 °C for 0.5 - 2 h, then adds water to form a pulp solution, and after mixing evenly with alkali, conducts atmospheric alkaline oxidation to obtain a gold leaching agent. After in-situ gold leaching with the gold leaching agent, a gold-containing leaching solution is obtained. Subsequently, after adding a certain concentration of copper sulfate and ammonia water to the gold-containing leaching solution, the residual gold ore is intensively extracted. Although this method can save the consumption of external thiosulfate by generating thiosulfate through roasting in a high-temperature inert atmosphere first, it still has deficiencies: this method requires roasting pretreatment in a high-temperature inert atmosphere to achieve a better gold leaching effect, which requires external energy and the consumption of inert gas, the process flow is relatively complex, and the overall production cost is high.

[0007] The title of the doctoral dissertation of Beijing University of Science and Technology is "Research on the Mechanism and Process of Alkaline Pressure Self-leaching of Arsenic-containing Refractory Gold Ore", author Wu Hao, the article mentioned the alkaline pressure self-leaching method of arsenic-sulfur refractory gold ore, under the conditions of stirring speed 600rpm, oxygen pressure 0.5MPa, NaOH dosage 0.6M, liquid-solid ratio 5:1, CMC dosage 0.1g / L, temperature 35℃, sodium carbonate dosage 0.3M, leaching for 18h, the leaching rate reached more than 90%. The main shortcomings of this method are: 1. The leaching time is too long, and it is difficult to ensure production efficiency; 2. The use of pressure treatment has the problem that the generation process has high equipment requirements and is difficult to control some process parameters such as potential fluctuation range and pH value, which makes the leaching process uncontrollable.

[0008] In summary, in order to solve the above problems, break through relevant technical bottlenecks, and promote the industrial application of thiosulfate method for gold extraction, it is necessary to conduct more in-depth research and development. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides a method for in-situ self-excitation and enhanced gold leaching of Carlin-type fine gold ore. The present invention aims to make up for the deficiencies of the prior art and provide a method for in-situ self-excitation and enhanced gold leaching of Carlin-type fine gold ore to get rid of the difficulties existing in the existing gold leaching process. The method maintains the redox potential and pH value of the leaching system at normal temperature and pressure, so that it is continuously in an appropriate range, thereby self-exciting and dissociating the inherent sulfur in the gold-bearing sulfide minerals in the Carlin-type fine gold ore into thiosulfate ions, and simultaneously destroys its wrapping structure for gold, so that gold and the in-situ generated gold leaching agent are in good contact, and a stable thiosulfate gold complex is generated, thereby achieving effective leaching of gold. The method of the present invention adopts in-situ self-excitation to form thiosulfate and in-situ gold extraction, which not only saves the consumption of external thiosulfate, but also does not require pretreatment during the gold leaching process, the process is simpler, the production cost is lower, and while ensuring a good gold extraction rate, there is no special demand for equipment, and the system is more controllable.

[0010] The technical solution of the present invention:

[0011] A method for in-situ self-excitation and enhanced gold leaching of Carlin-type refined gold ore is disclosed. An oxidant and an alkaline reagent are added to a slurry system of the Carlin-type refined gold ore in a continuous, slow and appropriate manner at room temperature and pressure, and the oxidation potential of the slurry system is maintained at -600 to -15.3 mV and the pH value is maintained at 7 to 11, so that gold-bearing sulfide minerals in the refined gold ore are in-situ oxidized in the leaching system to generate stable thiosulfate as a gold leaching agent, thereby achieving in-situ self-excitation and enhanced gold leaching of the Carlin-type refined gold ore.

[0012] Preferably, the aforementioned method for in-situ self-excitation and enhanced gold leaching of Carlin-type gold concentrate comprises the following steps:

[0013] S1. Take refined gold ore powder and set it aside;

[0014] S2. Add water and an alkaline reagent to the refined gold ore powder to prepare an alkaline gold ore pulp;

[0015] S3. At normal temperature and pressure, add an oxidizing agent and an alkaline reagent to the alkaline gold ore pulp in a continuous, slow, and appropriate addition manner, stir, and maintain the oxidation potential of the refined gold ore pulp system between -600 and -15.3 mV, and keep the pH value between 7 and 11, so that the gold-bearing sulfide minerals in the refined gold ore are in-situ oxidized to form stable thiosulfate as a gold leaching agent in the leaching system and perform self-excited leaching to obtain a gold-containing leachate;

[0016] S4. Add a strengthened gold leaching agent to the gold-containing leachate, stir, and perform strengthened leaching to obtain a strengthened leachate;

[0017] S5. Filter and wash the strengthened leachate, and incorporate the washing liquid into the filtrate together to obtain a gold-containing precious liquid;

[0018] S6. Use a conventional gold extraction process to extract gold from the gold-containing precious liquid to obtain gold; the conventional gold extraction process described in this step is gold extraction by activated carbon adsorption or extraction process.

[0019] Preferably, in the aforementioned method for in-situ self-excited and strengthened leaching of Carlin-type refined gold ore, the gold content of the Carlin-type refined gold ore is 10.9 - 28.3 g / t, the total sulfur content is 18.34 - 45.5 wt%, the arsenic content is 1.56 - 2.16 wt%, and the gold encapsulated by arsenic sulfide ore in the gold ore is 70.4 - 80.6 wt%.

[0020] Preferably, in the aforementioned method for in-situ self-excited and strengthened leaching of Carlin-type refined gold ore, the liquid-solid ratio in the alkaline gold ore pulp described in S2 is 5:1 - 10:1.

[0021] Preferably, in the aforementioned method for in-situ self-excited and strengthened leaching of Carlin-type refined gold ore, the oxidizing agent described in S3 is hydrogen peroxide, and the concentration of hydrogen peroxide is 0.3 - 1.5 mol / L; or the oxidizing agent is oxygen or ozone, and the volume concentration of oxygen or ozone is 60 - 99.2%; the alkaline reagents described in S2 and S3 are sodium hydroxide or potassium hydroxide.

[0022] Preferably, in the aforementioned method for in-situ self-excited and strengthened leaching of Carlin-type refined gold ore, the time for self-excited leaching described in S3 is 1 - 3 h.

[0023] Preferably, in the aforementioned method for in-situ self-excited and strengthened leaching of Carlin-type refined gold ore, the stirring speed in S3 and S4 is 450 - 800 rpm.

[0024] Preferably, in the method for in-situ self-excitation and enhanced gold leaching of the foregoing Carlin-type refined gold ore, the enhanced gold leaching agent described in S4 is a mixed solution of copper sulfate solution and ethylenediamine solution.

[0025] Preferably, in the method for in-situ self-excitation and enhanced gold leaching of the foregoing Carlin-type refined gold ore, the concentration of copper sulfate in the mixed solution is 0.05 - 0.2 mol / L, and the concentration of ethylenediamine is 0.05 - 0.15 mol / L; the liquid-solid ratio of the mixed solution to the solid phase in the gold-containing leaching product is 3:1 - 5:1.

[0026] Preferably, in the method for in-situ self-excitation and enhanced gold leaching of the foregoing Carlin-type refined gold ore, the time for enhanced leaching described in S4 is 2 - 4 h.

[0027] Advantages of the present invention:

[0028] 1. The method of the present invention belongs to the in-situ self-excitation thiosulfate gold leaching process. Compared with the traditional thiosulfate gold leaching method, the present invention can significantly save the consumption of external thiosulfate and save the gold leaching cost.

[0029] 2. The present invention adds an oxidant and an alkaline reagent to the gold ore pulp system in a continuous, slow, and appropriate amount at normal temperature and pressure, and maintains the oxidation potential and pH value in the reaction system, so that the thiosulfate formed by in-situ self-excitation is always in a stable state, enabling it to maintain a good gold leaching effect. Compared with the existing thiosulfate gold extraction technology, the method of the present invention does not require any pretreatment and does not require a high-temperature and high-pressure environment. It only needs to prepare the refined gold ore powder into a pulp and carry out in-situ oxidation self-excitation gold leaching at normal temperature and pressure. Therefore, the gold leaching process is simpler, the production cost is lower, and there is no special requirement for equipment while ensuring a good gold extraction rate, and the system is more controllable.

[0030] In summary, the method of the present invention has the advantages of high gold extraction rate, simpler gold leaching process, no special equipment requirements, lower production cost, and more controllable system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the process flow chart of the method of the present invention;

[0032] Figure 2 is the E-pH diagram of the S-H2O system at 298.15K drawn through thermodynamic calculation;

[0033] Figure 3 is the E-pH diagram of the S-Au-H2O system at 298.15K drawn through thermodynamic calculation.

[0034] It can be seen from Figure 2 that S element will exist in the aqueous solution in various ionic forms, and S can exist in the solution 2-, S2O3 2- , S4O6 2- , S3O6 2- , SO3 2- Plasma, S2O3 2- The stable existence region (ABCD) of S2O3 is at a relatively negative potential, approximately -546.8 mV to -15.3 mV, and the region range is small. If the oxidation potential in the leaching system is within this range and the appropriate pH value is controlled, the formation of S2O3 can be achieved. 2- Using H2O2 for in-situ self-excitation of Carlin-type refractory gold ore and adding NaOH to adjust the pH value of the system to be alkaline, the main reactions that may occur are:

[0035] 2OH - + FeS2 + 7.5H2O2 = S2O3 2- + Fe(OH)3↓ + 7H2O + 2O2↑ (1)

[0036] 4OH - + FeS2 + 15.5H2O2 = 2SO4 2- + Fe(OH)3↓ + 16H2O + 4O2↑ (2)

[0037] 4OH - + FeS2 + 13.5H2O2 = 2SO3 2- + Fe(OH)3↓ + 14H2O + 4O2↑ (3)

[0038] 2OH - + FeS2 + 7H2O2 = S2O3 2- + Fe(OH)2↓ + 7H2O + 2O2↑ (4)

[0039] FeAsS + 7H2O2 + 5OH - = Fe(OH)3↓ + SO4 2- + AsO4 3- + 8H2O (5)

[0040] Using O2 or the oxidation product O2 in the system may also in-situ self-excite pyrite to generate thiosulfate:

[0041] 2FeS2 + 3.5O2 + 4OH - + H2O = 2S2O3 2- + 2Fe(OH)3↓ (6)

[0042] Calculated, the Δ r G θThey are -1580.89 kJ / mol, -840.415 kJ / mol, -658.699 kJ / mol, -605.843 kJ / mol, -341.335 kJ / mol, and -337.564 kJ / mol in sequence, all having a spontaneous tendency. From the above equations, it can be seen that conventional oxidants such as H2O2 and O2 can oxidize and dissociate the gold-bearing minerals arsenopyrite and pyrite in refractory gold ore. The arsenic element in arsenopyrite will ultimately enter the solution in the form of AsO4 3- and the S2 2- in pyrite will enter the solution in different valence states such as S2O3 2- , SO3 2 , and SO4 2- and other forms. By adopting the specific addition method of the oxidant (such as H2O2) and the synergistic effect of other process conditions of the present invention, the in-situ oxidation and self-excitation of gold-bearing sulfide minerals are promoted to enable the sufficient and effective occurrence of reaction formulas (1), (4), and (6), allowing S2O3 2- to be generated and stably exist in an appropriate amount in the system, opening the encapsulation while enabling gold to enter the leaching system, creating extremely favorable conditions for the subsequent gold leaching.

[0043] The in-situ self-excitation effect of the present invention is to control the oxidation potential and pH value of the system in a specific manner. The specific control region is such as the quadrilateral region ABCD in the Figure 2 central position. By observing this region, it is not difficult to find that under acidic conditions, by controlling an appropriate redox potential, the generation of S2O3 2- can also be achieved, but it is extremely easy to decompose, and at the same time, toxic gases such as H2S and SO2 will be generated, and the anti-corrosion requirements for equipment are high. Therefore, it is more appropriate to select a slightly alkaline leaching environment. The specific reactions are as follows:

[0044] S2O3 2- + 2H + = S↓ + H2O + SO2↑ (7)

[0045] FeS2 + 2H + = Fe 2+ + H2S↑ (8)

[0046] 4FeS2 + 11H2O2 + 6H + = 14H2O + 2Fe 3+ + 8SO2↑ (9)

[0047] From thermodynamics Figure 2 , 3 it can be known that there is a situation where the thermodynamic stable region of S2O3 2- in aqueous solution overlaps with the stable region of Au(S2O3)2 2- . This overlapping part is located in the Figure 3Near neutral pH value and a potential of 0 mV, which provides important theoretical support for the in-situ self-excited generation of S2O3 2- and the synchronous dissolution of gold. Detailed implementation manners

[0048] The present invention will be further described below in conjunction with embodiments, but it shall not be used as a basis for limiting the present invention.

[0049] Embodiments of the present invention

[0050] Embodiment 1

[0051] The Carlin-type refractory gold ore from an enterprise in Guizhou, in which the metal minerals in the ore are mainly fine-grained disseminated pyrite and arsenopyrite, and the non-metal minerals are mainly mica, quartz, etc. Most of the gold is embedded in metal sulfides in the form of fine grains and submicroscopic particles. The gold content is 11.8 g / t, the sulfur mass percentage is 36.3%, and the arsenic mass percentage content is 1.81%. The particle size of this ore with 60 - 90 μm accounts for 91.3%. Among them, the proportion of gold wrapped by gold-bearing minerals is 80.1%. The specific implementation steps are as follows:

[0052] (1) Prepare a pulp solution by mixing Carlin-type refractory gold ore powder and a certain volume of water, and use NaOH to mix evenly to adjust the initial pH value to 11, and prepare an alkaline pulp with a liquid-solid mass ratio of 5:1;

[0053] (2) Continuously and slowly add 0.3 mol / L hydrogen peroxide solution to the alkaline pulp within 1.5 h, control the oxidation potential of the system to be between -560 ± 20 mV, and at the same time continuously and slowly add sodium hydroxide to the alkaline pulp within 1.5 h to control the pH value of the system to be maintained near 11. During the addition process, the stirring intensity is 450 r / min and the temperature is 40 °C, and perform alkaline in-situ self-excited leaching under normal pressure for 2 h to obtain a gold-containing leachate; use the iodometric method to measure the concentration of thiosulfate in the gold-containing leachate, and the result is about 0.16 mol / L;

[0054] (3) Add a mixed solution with a copper sulfate concentration of 0.1 mol / L and an ethylenediamine concentration of 0.1 mol / L to the above gold-containing leachate. The liquid-solid ratio of the mixed solution to the solid phase in the gold-containing leachate is 3:1 to form a copper-ethylenediamine-thiosulfate gold leaching system, so as to strengthen the gold extraction of the gold not leached in the system. During the strengthening gold extraction, the stirring intensity is 450 r / min, the temperature drops to 25 °C, and the leaching time is 2.5 h;

[0055] (4) After the strengthening gold extraction, filter, wash the filter residue and combine the filtrates, and extract gold from the filtrates through a conventional gold extraction process.

[0056] Calculated by the mass and gold content of the residue, the gold leaching rate of the process in the above embodiment is 81.1%.

[0057] Example 2

[0058] The Carlin-type refractory gold ore from an enterprise in Guizhou has fine-grained and dispersed pyrite and arsenopyrite as the main metal minerals in the ore, while the non-metal minerals are mainly mica, quartz, etc. Gold is mostly embedded in metal sulfides in the form of fine grains and submicroscopic particles. The gold content is 12.06 g / t, the total sulfur mass percentage is 45.5%, and the mass percentage content of arsenic is 2.02%. The particle size of this ore with 60 - 90 μm accounts for 90.5%, and the proportion of gold-bearing minerals wrapping gold is 79.7%. The specific implementation steps are as follows:

[0059] (1) Prepare a pulp solution by mixing Carlin-type refractory gold ore powder and a certain volume of water, and use KOH to mix evenly to adjust the pH value to 9, and prepare an alkaline pulp with a liquid-solid mass ratio of 6:1;

[0060] (2) Continuously and slowly add 1.5 mol / L hydrogen peroxide solution to the alkaline pulp in batches within 0.8 h, control the oxidation potential of the system to be between -312 ± 20 mV, and at the same time continuously and slowly add sodium hydroxide to the alkaline pulp within 0.8 h, control the pH value of the system to be maintained near 9. During the addition process, the stirring intensity is 450 r / min and the temperature is 30 °C for atmospheric pressure alkaline in-situ self-excited leaching for 1 h to obtain a gold-containing leaching solution; Use the iodometric method to measure the concentration of thiosulfate in the gold-containing leaching solution, and the result is about 0.17 mol / L;

[0061] (3) Add a mixed solution with a copper sulfate concentration of 0.15 mol / L and an ethylenediamine concentration of 0.15 mol / L to the above gold-containing leaching solution. The liquid-solid ratio of the mixed solution to the solid phase in the gold-containing leaching solution is 4:1 to form a copper-ethylenediamine-thiosulfate gold leaching system, which can strengthen the gold extraction of the unextracted gold in the solution. During the strengthening gold extraction, the stirring intensity is 500 r / min, the temperature drops to 25 °C, and the leaching time is 3 h;

[0062] (4) After the strengthening gold extraction, filter, wash the filter residue and combine the filtrate, and extract gold from the filtrate through a conventional gold extraction process.

[0063] The total gold leaching rate obtained by calculating through the mass and gold content of the residue in the above process is 83.6%.

[0064] Example 3

[0065] The Carlin-type refractory gold ore from an enterprise in Guizhou, in which the metallic minerals in the ore are mainly fine-grained disseminated pyrite and arsenopyrite, and the non-metallic minerals are mainly mica, quartz, etc. Gold is mostly embedded in metal sulfides in the form of fine grains and submicroscopic particles. The gold content is 15.67 g / t, the total sulfur mass percentage is 44.2%, and the mass percentage content of arsenic is 1.89%. The particle size of this ore is 60 - 90 μm accounting for 90.8%, and the proportion of gold wrapped by gold-bearing minerals is 70.4%. The specific implementation steps are as follows:

[0066] (1) Prepare a pulp solution by mixing Carlin-type refractory gold ore powder and a certain volume of water, and use NaOH to mix evenly to adjust the pH value to 8.5, and prepare an alkaline pulp with a liquid-solid mass ratio of 8:1;

[0067] (2) Continuously and slowly add 1 mol / L hydrogen peroxide solution to the alkaline pulp within 2.0 h, control the oxidation potential of the system to be between -245 ± 20 mV. At the same time, continuously and slowly add sodium hydroxide to the alkaline pulp within 2.0 h, control the pH value of the system to be maintained near 8.5. During the addition process, the stirring intensity is 600 r / min and the temperature is 35 °C for atmospheric pressure alkaline in-situ self-excited leaching for 3 h to obtain a gold-containing leaching solution. Use the iodometric method to measure the concentration of thiosulfate in the gold-containing leaching solution, and the result is about 0.20 mol / L;

[0068] (3) Add a mixed solution with a copper sulfate concentration of 0.2 mol / L and an ethylenediamine concentration of 0.15 mol / L to the above gold-containing leaching solution. The liquid-solid ratio of the mixed solution to the solid phase in the gold-containing leaching solution is 4:1 to form a copper-ethylenediamine-thiosulfate gold leaching system, and then the gold that has not been leached in the system can be intensively leached. During the intensive gold leaching, the stirring intensity is 600 r / min, the temperature drops to 30 °C, and the leaching time is 2.5 h;

[0069] (4) After intensive gold leaching, filter, wash the filter residue and combine the filtrate, and extract gold from the filtrate through a conventional gold extraction process.

[0070] Calculated by the mass and gold content of the residue, the total gold leaching rate obtained by the above process is 84.6%.

[0071] Example 4

[0072] The Carlin-type refractory gold ore from an enterprise in Guizhou, in which the metallic minerals in the ore are mainly fine-grained disseminated pyrite and arsenopyrite, and the non-metallic minerals are mainly mica, quartz, etc. Gold is mostly embedded in metal sulfides in the form of fine grains and submicroscopic particles. The gold content is 21.3 g / t, the total sulfur mass percentage is 42.3%, and the mass percentage content of arsenic is 1.56%. The particle size of this ore is 60 - 90 μm accounting for 90.8%, and the proportion of gold wrapped by gold-bearing minerals is 80.6%. The specific implementation steps are as follows:

[0073] (1) Prepare a pulp solution by mixing Carlin-type fine gold ore powder with a certain volume of water. Use NaOH to mix evenly and adjust the pH value to 7.5. The prepared solution has a liquid-solid mass ratio of 10:1;

[0074] (2) Continuously and slowly add 0.7 mol / L hydrogen peroxide solution to the alkaline pulp within 1.5 h, control the oxidation potential of the system to be between -35.3 ± 10 mV. At the same time, continuously and slowly add sodium hydroxide to the alkaline pulp within 1.5 h, control the pH value of the system to remain near 7.5. During the addition process, stir at a strength of 800 r / min and a temperature of 40 °C for 2.5 h of atmospheric pressure alkaline in-situ self-excited leaching to obtain a gold-containing leaching solution; Use the iodometric method to measure the concentration of thiosulfate in the gold-containing leaching solution, and the result is about 0.25 mol / L;

[0075] (3) Add a mixed solution with a copper sulfate concentration of 0.05 mol / L and an ethylenediamine concentration of 0.05 mol / L to the above gold-containing leaching solution. The liquid-solid ratio of the mixed solution to the solid phase in the gold-containing leaching solution is 5:1 to form a copper-ethylenediamine-thiosulfate gold leaching system, which can strengthen the gold extraction of the unextracted gold in the system. When strengthening the gold extraction, stir at a strength of 800 r / min, lower the temperature to 25 °C, and the leaching time is 2.5 h;

[0076] (4) After strengthening the gold extraction, filter, wash the filter residue and combine the filtrates. The filtrates are used to extract gold through a conventional gold extraction process.

[0077] Calculated by the mass and gold content of the residue, the total gold leaching rate obtained by the process of the above example is 80.7%.

[0078] Example 5

[0079] The Carlin-type fine gold ore from a certain enterprise in Guizhou, the metal minerals in its ore are mainly fine-grained dispersed pyrite and arsenopyrite, and the non-metal minerals are mainly mica, quartz, etc. Gold is mostly embedded in metal sulfides in the form of fine grains and submicroscopic forms. The gold content is 17.32 g / t, of which the total sulfur mass percentage is 45.2%, and the mass percentage content of arsenic is 2.16%. The particle size of this ore is 60 - 90 μm accounting for 91.2%, and the proportion of gold-bearing minerals wrapping gold is 77.4%. The specific implementation steps are as follows:

[0080] This example is consistent with the process of Example 2, the difference is that: the oxidant used in this example is ozone, with a volume concentration of 50%. Similarly, continuously supply the oxidant to maintain the potential of the system between -550 and -20 mV. After atmospheric pressure alkaline in-situ self-excitation and solid-liquid separation, use the iodometric method to measure the thiosulfate content in the gold-containing leaching solution, and the result shows a concentration of 0.16 mol / L.

[0081] Based on the calculation of the quality and gold content of the residue, the total leaching rate of gold obtained by the process of the above embodiment is 79.6%.

[0082] Example 6

[0083] This example is the same as Example 5 in terms of process and gold ore raw materials, except that: the volume concentration of ozone used in this example is 99.2%.

[0084] Based on the calculation of the quality and gold content of the residue, the total leaching rate of gold obtained by the process of the above embodiment is 81.7%.

[0085] Example 7

[0086] This example is the same as Example 5 in terms of process and gold ore raw materials, except that: the volume concentration of ozone used in this example is 60%.

[0087] Based on the calculation of the quality and gold content of the residue, the total leaching rate of gold obtained by the process of the above embodiment is 77.8%.

[0088] Example 8

[0089] The Carlin-type refined gold ore from an enterprise in Guizhou, in which the metal minerals in the ore are mainly fine-grained disseminated pyrite and arsenopyrite, and the non-metal minerals are mainly mica, quartz, etc. Gold is mostly embedded in metal sulfides in the form of fine grains and submicroscopic particles. The gold content is 16.4 g / t, the total sulfur mass percentage is 45.1%, and the mass percentage content of arsenic is 2.07%. 91.2% of the ore has a particle size of 60 - 90 μm, and the proportion of gold-bearing minerals wrapping gold is 76.2%. The specific implementation steps are as follows:

[0090] This example is the same as Example 2 in terms of process, except that: the oxidant is oxygen with a volume concentration of 99.2%. After continuous supply and atmospheric pressure alkaline in-situ self-excited solid-liquid separation, the thiosulfate content in the gold-bearing leaching solution is measured by the iodometric method, and the result shows that the concentration is 0.19 mol / L.

[0091] Based on the calculation of the quality and gold content of the residue, the total leaching rate of gold obtained by the process of the above embodiment is 83.6%.

[0092] Comparative Example 1

[0093] Replace the Carlin-type refined gold ore of an enterprise in Guizhou in Example 3 with the original Carlin-type gold ore in Guizhou, and other experimental operations and conditions are the same as those in Example 3.

[0094] Specifically, the replaced primary ore of Carlin-type gold deposit has fine-grained and disseminated pyrite and arsenopyrite as the main metallic minerals, while the non-metallic minerals are mainly mica, quartz, etc. A small amount of gold is embedded in metal sulfides in the form of fine grains and submicroscopic particles. After crushing and ball milling, the particle size of the ore is 60 - 90μm, accounting for 90.8%, the gold content is 4.6g / t, the total sulfur mass percentage is 8.34%, the arsenic mass percentage content is 0.13%, and the proportion of gold wrapped by gold-bearing minerals is 20.7%.

[0095] After the solution obtained by atmospheric pressure alkaline in-situ self-excitation is separated by solid-liquid separation, the thiosulfate content in the gold-bearing leaching solution is determined by the iodometric method, and the concentration is obtained as 0.038mol / L. Compared with Example 3 with a relatively high sulfur content in refined gold ore, the thiosulfate concentration in this comparative example is relatively low, which is mainly due to the relatively small sulfur element content in the primary ore. Under the condition of the same sulfur conversion rate, the total amount of thiosulfate generated is correspondingly reduced.

[0096] The process of this example not only utilizes the sulfur in the gold-bearing minerals in the gold ore but also opens the inclusions of gold in the gold-bearing minerals. To verify the process effect, a primary ore comparative experiment is carried out. Under the same enhanced gold leaching conditions, it is calculated through the mass and gold content of the residue that the total gold leaching rate of the process in this example is only 28.6%.

[0097] Comparative Example 2

[0098] The addition method of hydrogen peroxide in Example 3 is changed from continuous and slow addition to one-time input, and other experimental operations and conditions are the same as those in Example 3. The iodometric method is used to measure the concentration of thiosulfate in the gold-bearing leaching solution, and the result is about 0.013mol / L. Compared with Example 3, its content is significantly reduced. Through the analysis of experimental phenomena and reaction products, it is preliminarily determined that in the one-time addition method, the reaction is too intense in the initial stage, resulting in local high-concentration peroxidation to generate SO4 2- , in the middle and late stages of the reaction, hydrogen peroxide will react and decompose by itself, and the potential and pH value in the system fluctuate greatly and are difficult to control, making it extremely difficult for S2O3 2- to be generated and stably exist.

[0099] The calculated total gold leaching rate obtained by the process of the above example is 31.2%.

[0100] Comparative Example 3

[0101] The in-situ self-excitation mode of Example 8 was changed from continuously supplying oxygen with a concentration of 99.2% to oxygen with a concentration of 30%, and other experimental operations and conditions were the same as those in Example 8. The thiosulfate content in the gold-containing leaching solution was determined by the iodometric method, and the result showed a concentration of 0.014 mol / L. After analysis, this was mainly attributed to the following factors: First, the oxygen concentration in the leaching system was insufficient, lacking sufficient oxygen pressure; second, due to the low diffusion coefficient of oxygen in the gold leaching system, the overall oxidation ability of the system was insufficient, which in turn affected the generation and stability of thiosulfate.

[0102] Through the calculation of the mass and gold content of the slag, the total leaching rate of the process gold in the above example was obtained as 51.2%.

[0103] As described above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A method for in-situ self-excitation and enhanced gold leaching of Carlin-type gold ore, characterized in that: At room temperature and pressure, an oxidant and an alkaline reagent are added to the slurry system of the Carlin-type fine gold ore in a continuous, slow and appropriate manner, and the oxidation potential of the slurry system is maintained at -600 to -15.3 mV and the pH value is maintained at 7 to 11, so that the gold-bearing sulfide minerals in the fine gold ore are in situ oxidized in the leaching system to generate stable thiosulfate as a gold leaching agent, thereby realizing in-situ self-excitation and enhanced gold leaching of the Carlin-type fine gold ore.

2. The method for in-situ self-excitation and enhanced gold leaching of Carlin-type gold ore according to claim 1, characterized in that: The steps include: S1. Take the refined gold ore powder and set aside; S2. adding water and an alkaline reagent to the refined gold ore powder to prepare an alkaline gold ore slurry; S3. At room temperature and pressure, an oxidant and an alkaline reagent are added to the alkaline gold ore pulp in a continuous and slow manner in an appropriate amount, and the oxidation potential of the refined gold ore pulp system is maintained between -600 and -15.3 mV, and the pH value is maintained between 7 and 11, so that the gold-bearing sulfide minerals in the refined gold ore are in situ oxidized in the leaching system to generate stable thiosulfate as a gold leaching agent and self-excited leaching is performed to obtain a gold-containing leachate; S4. Adding a gold-enhancing leaching agent to the gold-containing leaching product, stirring and performing enhanced leaching to obtain an enhanced leaching product; S5. The enhanced extract is filtered and washed, and the washing liquid is incorporated into the filtrate to obtain a precious liquid containing gold; S6. The gold-containing precious liquid is extracted with conventional gold extraction technology to obtain gold.

3. The method for in-situ self-excitation and enhanced gold leaching of Carlin-type gold concentrate according to claim 1 or 2, characterized in that: The Carlin-type gold concentrate has a gold content of 10.9-28.3 g / t, a total sulfur content of 18.34-45.5 wt%, an arsenic content of 1.56-2.16 wt%, and 70.4-80.6 wt% of the gold in the gold ore is encapsulated by arsenic sulfide ore.

4. The method for in-situ self-excitation and enhanced gold leaching of Carlin-type gold ore according to claim 2, characterized in that: The liquid-to-solid ratio in the alkaline gold ore slurry described in S2 is 5:1-10:

1.

5. The method for in-situ self-excitation and enhanced gold leaching of Carlin-type gold concentrate according to claim 2, characterized in that: The oxidant in S3 is hydrogen peroxide, and the concentration of hydrogen peroxide is 0.3-1.5 mol / L; or the oxidant is oxygen or ozone, and the volume concentration of oxygen or ozone is 60-99.2%; the alkaline reagent in S2 and S3 is sodium hydroxide or potassium hydroxide.

6. The method for in-situ self-excitation and enhanced gold leaching of Carlin-type gold concentrate according to claim 2, characterized in that: The self-excited leaching time in S3 is 1-3h.

7. The method for in-situ self-excitation and enhanced gold leaching of Carlin-type gold concentrate according to claim 2, characterized in that: The stirring speed in S3 and S4 is 450-800 rpm.

8. The method for in-situ self-excitation and enhanced gold leaching of Carlin-type gold concentrate according to claim 2, characterized in that: S4 The enhanced gold leaching agent is a mixture of copper sulfate solution and ethylenediamine solution.

9. The method for in-situ self-excitation and enhanced gold leaching of Carlin-type gold concentrate according to claim 8, characterized in that: The concentration of copper sulfate in the mixed solution is 0.05-0.2 mol / L, and the concentration of ethylenediamine is 0.05-0.15 mol / L; the liquid-to-solid ratio of the mixed solution to the solid phase in the gold-containing leaching material is 3:1-5:

1.

10. The method for in-situ self-excitation and enhanced gold leaching of Carlin-type gold concentrate according to claim 2, characterized in that: The time of the enhanced leaching in S4 is 2-4h.

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