A method of inhibiting the gold thieving effect of organic carbon gold ores during cyanide leaching

Abstract

The present application relates to the technical field of precious metal smelting, and particularly relates to a method for inhibiting the gold stealing effect of organic carbon gold ore in a cyanide leaching process.The method for inhibiting the gold stealing effect of organic carbon gold ore in a cyanide leaching process provided by the present application comprises the following steps: (1) crushing carbonaceous gold ore to obtain crushed ore; (2) grinding the crushed ore, adding an organic carbon shielding agent during the grinding process or adding the organic carbon shielding agent after the grinding process and performing intensive stirring treatment; the organic carbon shielding agent is a hydrophobic organic polymer with high viscosity and high molecular weight; (3) adjusting the pH, adding sodium cyanide for leaching, and then adding activated carbon for stirring treatment for adsorption.

Description

Technical Field

[0001] This invention relates to the field of precious metal smelting technology, specifically to a method for suppressing the gold-stealing effect of organocarbon gold ores during cyanide leaching. Background Technology

[0002] Carbonaceous gold deposits, especially Carlin-type gold deposits, present significant gold robbery problems due to the presence of natural organic carbon such as graphite and bitumen. Carbonaceous materials, with their adsorption properties similar to activated carbon, adsorb gold cyanide complex ions after cyanide leaching, greatly reducing the gold leaching recovery rate. This is a recognized beneficiation problem in the industry.

[0003] Currently, the four mainstream industrial processes—direct cyanidation, roasting-carbon leaching, flotation-oxidation-carbon leaching, and thiosulfate leaching—all have significant shortcomings: roasting processes have high energy consumption, easily generate harmful arsenic and mercury fumes, and face significant environmental pressure; oxidation pretreatment cannot completely eliminate the problem of carbonaceous gold robbery, limiting the upper limit of gold extraction; conventional liquid shielding agents are prone to activated carbon poisoning, have high reagent consumption, and poor stability; and the thiosulfate leaching system has weak stability, and the industrialization of supporting gold extraction processes is difficult, resulting in high production costs.

[0004] Existing technologies generally suffer from poor process adaptability, insufficient environmental protection, and easy depletion of activated carbon adsorption performance. They have always been unable to simultaneously meet the three core requirements of efficient shielding against carbonaceous gold robbery, preserving the gold extraction efficiency of activated carbon, and adapting to conventional industrial production lines. Therefore, there is an urgent need to develop a new organic carbon shielding technology that is compatible with the existing cyanide-carbon slurry process, stable, efficient, and low-cost. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention proposes a method for improving the shielding effect of organic carbon shielding agents.

[0006] The method of the present invention for suppressing the gold-stealing effect of organocarbon gold ores during cyanide leaching is characterized by comprising the following steps: (1) The carbonaceous gold ore is crushed to obtain crushed ore; (2) The crushed ore is ground, and an organic carbon shielding agent is added during the grinding process or after the grinding process and then subjected to enhanced stirring; the organic carbon shielding agent is a high-viscosity, high-molecular-weight hydrophobic organic polymer. (3) After adjusting the pH, sodium cyanide is added for leaching, and then activated carbon is added and stirred for adsorption.

[0007] The advantages and technical effects of the method for suppressing the gold-stealing effect of organocarbon gold ore during cyanide leaching of the present invention are as follows: 1. The method of the present invention uses a high molecular weight, high viscosity hydrophobic polymer as an organocarbon shielding agent. During grinding or enhanced stirring, the polymer molecular chains of the organocarbon shielding agent are stretched and spread under high shear conditions, achieving preferential and enhanced adsorption on the surface of organocarbon, thereby forming a dense and stable composite adsorption layer on the surface of organocarbon. During subsequent low-shear cyanide leaching, this layer is not easily desorbed from the surface of organocarbon or migrates to activated carbon, thus not affecting the adsorption of gold cyanide complex ions by activated carbon and avoiding the problem of "shielding agent contaminating activated carbon". 1. To ensure stable operation of sodium cyanide leaching and activated carbon adsorption; 2. The method of the present invention adopts a "high shear-induced adsorption + low shear-maintained stability" mechanism. In the high shear stage such as grinding, the shielding agent preferentially adsorbs organic carbon. In the low shear stage such as leaching and adsorption, the shielding layer remains stable and does not desorb, significantly improving the stability and durability of the shielding effect; 3. The method of the present invention uses an organic carbon shielding agent with a high molecular chain structure and high viscosity system, which can enter the microporous structure of organic carbon under high shear and cover colloidal organic carbon particles. Compared with traditional oils, which can only cover coarse particles, the shielding is more comprehensive and thorough, which can significantly reduce the adsorption of gold cyanide complex ions by organic carbon and reduce the phenomenon of carbon stealing gold. It can significantly reduce the gold theft index in carbonaceous ores and increase the gold leaching recovery rate by about 5-35%; 4. The method of the present invention does not rely on high-temperature slurry and can be implemented directly under conventional grinding temperature (room temperature or slightly heated) conditions. It is suitable for existing CIL / CIP processes, and the shielding agent is not easy to migrate and does not undergo large-scale redispersion. Therefore, the actual effective utilization rate is high, the dosage can be reduced, and the frequency of activated carbon regeneration is reduced, thereby reducing the overall production cost. Therefore, the process is highly adaptable, no new heating equipment is required, and it is easy to promote industrially.

[0008] Optionally, in step (2), the hydrophobic organic polymer includes at least one of polyisobutylene, polyα-olefin, polybutene, polybutadiene, or liquid styrene-butadiene rubber.

[0009] Optionally, in step (2), the weight-average molecular weight of the hydrophobic organic polymer is 500~5000, and the viscosity of the hydrophobic organic polymer is 100~5000000 mPa·s.

[0010] Optionally, in step (2), the amount of organic carbon shielding agent added is 50~5000 g / t.

[0011] Optionally, in step (2), the stirring intensity of the grinding process is greater than 10 kW / m. 3 .

[0012] Optionally, the intensity of the enhanced stirring treatment is 1~3 kW / m 3The time for enhanced stirring is 15-30 minutes.

[0013] Optionally, in step (3), the pH is adjusted to 10.5~12.

[0014] Optionally, in step (3), the amount of sodium cyanide added is 0.2~1.5 kg / t, the leaching time is 16~36 hours, and the leaching process is carried out at a rate of 0.2~0.5 kW / m 3 Stir with the required intensity.

[0015] Optionally, in step (3), the amount of activated carbon added is 20~40 g / L, and the stirring intensity is 0.5~1.0 kW / m. 3 The adsorption time is 12-28 hours.

[0016] Optionally, in step (1), the carbonaceous gold ore includes at least one of the following: Carlin-type gold ore, micro-disseminated carbonaceous gold ore, black shale-type gold ore, carbonaceous sedimentary gold ore, or graphite-type gold ore. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the process flow of the method of the present invention. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] like Figure 1 As shown, the method for suppressing the gold-stealing effect of organocarbon gold ores during cyanide leaching according to an embodiment of the present invention is characterized by comprising the following steps: (1) The carbonaceous gold ore is crushed to obtain crushed ore; (2) The crushed ore is ground, and an organic carbon shielding agent is added during the grinding process or after the grinding process and then subjected to enhanced stirring; the organic carbon shielding agent is a high-viscosity, high-molecular-weight hydrophobic organic polymer. (3) After adjusting the pH, sodium cyanide is added for leaching, and then activated carbon is added and stirred for adsorption.

[0020] The method for suppressing the gold-stealing effect of organocarbon gold ores during cyanide leaching in this invention employs a high-molecular-weight, high-viscosity hydrophobic polymer as an organocarbon shielding agent. During grinding or intensified stirring, the polymer molecular chains of the shielding agent are stretched and spread under high shear conditions, achieving preferential and enhanced adsorption on the organocarbon surface. This forms a dense and stable composite adsorption layer on the organocarbon surface, which is less prone to desorption from the organocarbon surface and migration to activated carbon during subsequent low-shear cyanide leaching. Therefore, it does not affect the adsorption of gold cyanide complex ions by activated carbon, avoiding the problem of "shielding agent contaminating activated carbon," and ensuring the leaching of sodium cyanide and activation... The method of this invention employs a "high shear-induced adsorption + low shear-maintained stability" mechanism. During high shear stages such as grinding, the shielding agent preferentially adsorbs organic carbon. During low shear stages such as leaching and adsorption, the shielding layer remains stable and does not desorb, significantly improving the stability and durability of the shielding effect. The method of this invention uses an organic carbon shielding agent with a high molecular chain structure and high viscosity system, which can enter the microporous structure of organic carbon and cover colloidal organic carbon particles under high shear. Compared with traditional oils, which can only cover coarse particles, this method provides a more comprehensive and thorough shielding effect, significantly reducing the adsorption of gold cyanide complex ions by organic carbon and reducing the phenomenon of gold robbery by carbon. This method can significantly reduce the gold theft index in carbonaceous ores and increase the gold leaching recovery rate by approximately 5-35%. The method in this embodiment of the invention does not rely on high-temperature slurry and can be implemented directly under conventional grinding temperatures (room temperature or slightly elevated temperature). It is suitable for existing CIL / CIP processes, and the shielding agent is not prone to migration or large-scale redispersion. Therefore, the actual effective utilization rate is high, the dosage can be reduced, and the frequency of activated carbon regeneration is reduced, thereby reducing the overall production cost. Therefore, the process is highly adaptable, requires no additional heating equipment, and is easy to promote industrially.

[0021] The organic carbon shielding agent in this invention operates through the following mechanism: (1) Adsorption priority principle: Carbonaceous materials in ores have high specific surface area and hydrophobic surface properties, which can strongly adsorb gold cyanide complex ions in the solution, thus producing the phenomenon of gold robbery by carbon. The molecular chains of hydrophobic polymers contain long-chain alkyl, aromatic or other hydrophobic side chains, which give them a high affinity for the surface of carbonaceous materials. When the polymer molecules are fully expanded under the high shear conditions of the slurry, the molecular chains form a physical adsorption or hydrophobic preferential layer with the surface of carbonaceous materials, thereby preventing gold complex ions from directly contacting the carbonaceous materials.

[0022] (2) Shear-induced adsorption mechanism: During the grinding or intensified stirring stage, the high shear force generated by the slurry can fully extend the polymer molecular chains, increasing the contact area between the chain segments and carbonaceous materials. The shearing effect not only increases the diffusion rate of polymer molecules, but also enhances the adsorption force between the polymer and the surface of carbonaceous materials, making the capping layer more uniform and dense. This adsorption remains stable under conditions of slurry flow cessation or low shear, and is not easily desorbed.

[0023] (3) High viscosity shielding effect: The hydrophobic polymer forms a high viscosity solution or local colloidal structure in the slurry, increasing the thickness of the adsorption layer formed on the surface of carbonaceous materials. This high viscosity shielding layer can reduce the contact frequency between gold complex ions and carbonaceous materials in the solution, thereby significantly weakening the re-adsorption behavior of gold. In the subsequent low-shear CIL / CIP stage, the polymer layer can still remain stable, and the polymer does not desorb, ensuring the efficient adsorption of gold complex ions by activated carbon.

[0024] (4) Chemical inertness and selectivity: The hydrophobic polymer is chemically stable and inert to gold cyanide complex ions and other components in the slurry. It hardly competes with activated carbon for the adsorption of gold cyanide complex ions. Its adsorption is mainly targeted at carbonaceous substances in the ore, without significantly affecting the adsorption capacity of activated carbon, thus achieving shielding selectivity.

[0025] (5) High viscosity locking mechanism and downstream stability: The high viscosity shielding layer formed by the hydrophobic polymer effectively reduces the contact probability between gold complex ions and carbonaceous substances in the solution, thereby inhibiting the gold robbery phenomenon. More importantly, the high viscosity significantly reduces the migration rate of the polymer in the subsequent low-shear leaching desorption and carbon slurry adsorption process, thereby preventing the polymer from transferring to the activated carbon surface and ensuring that the activated carbon maintains its high-efficiency adsorption capacity.

[0026] In some embodiments, preferably, in step (2), the hydrophobic organic polymer includes at least one of polyisobutylene, polyα-olefin, polybutene, polybutadiene, or liquid styrene-butadiene rubber.

[0027] In this embodiment of the invention, the type of organic polymer is preferred. The selected hydrophobic polymer has long-chain alkyl, aromatic or other hydrophobic side chains on its molecular chain, which makes it have a high affinity for carbonaceous material surfaces and is more conducive to reducing the occurrence of gold theft effect.

[0028] In some embodiments, preferably, in step (2), the weight-average molecular weight of the hydrophobic organic polymer is 500~5000, and the viscosity of the hydrophobic organic polymer is 100~5000000 mPa·s.

[0029] In some embodiments, preferably, in step (2), the amount of organic carbon shielding agent added is 50~5000g / t, such as 50g / t, 100g / t, 500g / t, 1000g / t, 2000g / t, 3000g / t, 4000g / t or 5000g / t, etc.

[0030] In this embodiment of the invention, the optimal amount of organic carbon shielding agent is selected to ensure complete coverage of the active sites on the organic carbon surface while controlling costs. If the amount of organic carbon shielding agent added is too low, it will not be sufficient to cover the active sites on the organic carbon surface, and the organic carbon will still maintain its strong gold-stealing ability; if the amount of organic carbon shielding agent added is too high, it will increase production costs without significantly improving the effect.

[0031] In some embodiments, preferably, in step (2), the stirring intensity of the grinding process is greater than 10 kW / m. 3 .

[0032] In some embodiments, preferably, the intensity of the enhanced stirring treatment is 1~3 kW / m 3 The intensified mixing treatment time is 15-30 minutes. Understandably, the intensity of the intensified mixing treatment is controlled at 1-3 kW / m². 3 It can fully induce the preferential adsorption of organic carbon shielding agents on the surface of organic carbon. Although further increasing the intensity of the enhanced stirring treatment will not bring adverse effects, it will cause energy waste and increase costs.

[0033] In some embodiments, preferably, in step (3), the pH is adjusted to 10.5~12.

[0034] In some embodiments, preferably, in step (3), the amount of sodium cyanide added is 0.2~1.5 kg / t, the leaching time is 16~36 hours, and the leaching process is carried out at a rate of 0.2~0.5 kW / m 3 Stir with the required intensity.

[0035] In some embodiments, preferably, in step (3), the amount of activated carbon added is 20~40 g / L, and the stirring intensity is 0.5~1.0 kW / m. 3 The adsorption time is 12-28 hours. During the cyanide leaching and activated carbon adsorption stages, since the stirring intensity of the slurry system is usually significantly lower than that during the grinding or enhanced stirring mixing stage, the adsorption layer formed by the high molecular organic matter can maintain high stability and is not easily desorbed from the carbonaceous material surface or transferred to the activated carbon surface.

[0036] In some embodiments, preferably, in step (1), the carbonaceous gold ore includes at least one of Carlin-type gold ore, micro-disseminated carbonaceous gold ore, black shale-type gold ore, carbonaceous sedimentary gold ore, or graphite-type gold ore.

[0037] The technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0038] Example 1 The ore used in this embodiment is oxidized Carlin-type gold ore containing 0.27 wt% organic carbon and 0.85 g / t gold, with a gold theft index of 2.1.

[0039] The processing steps are as follows: (1) The ore is crushed to obtain crushed ore with a particle size of less than 3 mm; (2) The crushed ore is ground. During the grinding process, organic carbon shielding agents of different viscosities and molecular weights are added. The amount of organic carbon shielding agent added is 1 kg / t, and the stirring intensity of the grinding process is 15 kW / m. 3 ; (3) Adjust the pH to pH 11 and add 0.5 kg / t sodium cyanide at 0.3 kW / m 3 The mixture was stirred at high intensity for 24 hours, and 30 g / L activated carbon was added at 0.5 kW / m³. 3 The adsorption was carried out under stirring intensity for 24 hours, and the results are shown in Table 1.

[0040] Table 1

[0041] Example 2 The ore used in this embodiment is oxidized Carlin-type gold ore containing 0.11% organic carbon and 0.73 g / t gold, with a gold theft index of 1.5.

[0042] The method in this embodiment is the same as that in embodiment 1, except that in step (2), the amount of organic carbon shielding agent added is 0.6 kg / t, and the results are shown in Table 2.

[0043] Table 2

[0044] Example 3 The ore used in this embodiment is the same as in Embodiment 1.

[0045] The method in this embodiment is the same as in embodiment 1, except that in step (2), after grinding the crushed ore, organic carbon shielding agents of different viscosities and molecular weights are added at 1.5 kW / m 3The stirring intensity was increased and the mixture was stirred for 20 minutes. The results are shown in Table 3.

[0046] Table 3

[0047] As can be seen from the results of the above examples, high molecular weight and high viscosity polymers have a significantly better shielding effect on organic carbon than low molecular weight polymers, and polymers containing aromatic structures exhibit better adsorption stability and shielding ability.

[0048] Comparative Example 1 The method for this comparative example is the same as that for Example 1, except that no organic carbon shielding agent is added in step (2), or kerosene is added as an organic carbon shielding agent. The results are shown in Table 4: Table 4

[0049] Comparative Example 2 The method for this comparative example is the same as that for Example 2, except that no organic carbon shielding agent is added in step (2), or kerosene is added as an organic carbon shielding agent. The results are shown in Table 5: Table 5

[0050] Comparative Example 3 The method for this comparative example is the same as that for Example 3, except that no organic carbon shielding agent is added in step (2), or kerosene is added as an organic carbon shielding agent. The results are shown in Table 6: Table 6

[0051] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0052] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A method for suppressing the gold-stealing effect of organocarbon gold ores during cyanide leaching, characterized in that, Includes the following steps: (1) The carbonaceous gold ore is crushed to obtain crushed ore; (2) The crushed ore is ground, and an organic carbon shielding agent is added during the grinding process or after the grinding process and then subjected to enhanced stirring; the organic carbon shielding agent is a high-viscosity, high-molecular-weight hydrophobic organic polymer. (3) After adjusting the pH, sodium cyanide is added for leaching, and then activated carbon is added and stirred for adsorption.

2. The method for suppressing the gold-stealing effect of organocarbon gold ores during cyanide leaching according to claim 1, characterized in that, In step (2), the hydrophobic organic polymer includes at least one of polyisobutylene, polyα-olefin, polybutene, polybutadiene, or liquid styrene-butadiene rubber.

3. The method for suppressing the gold-stealing effect of organocarbon gold ores during cyanide leaching according to claim 1 or 2, characterized in that, In step (2), the weight-average molecular weight of the hydrophobic organic polymer is 500~5000, and the viscosity of the hydrophobic organic polymer is 100~5000000 mPa·s.

4. The method for suppressing the gold-stealing effect of organocarbon gold ores during cyanide leaching according to claim 3, characterized in that, In step (2), the amount of organic carbon shielding agent added is 50~5000 g / t.

5. The method for suppressing the gold-stealing effect of organocarbon gold ores during cyanide leaching according to claim 1, characterized in that, In step (2), the stirring intensity of the grinding process is greater than 10 kW / m. 3 .

6. The method for suppressing the gold-stealing effect of organocarbon gold ores during cyanide leaching according to claim 1, characterized in that, In step (2), the intensity of the enhanced stirring treatment is 1~3 kW / m 3 The time for enhanced stirring is 15-30 minutes.

7. The method for suppressing the gold-stealing effect of organocarbon gold ores during cyanide leaching according to claim 1, characterized in that, In step (3), the pH is adjusted to 10.5~12.

8. The method for suppressing the gold-stealing effect of organocarbon gold ores during cyanide leaching according to claim 1, characterized in that, In step (3), the amount of sodium cyanide added is 0.2~1.5 kg / t, the leaching time is 16~36 hours, and the leaching process is carried out at a rate of 0.2~0.5 kW / m 3 Stir with the required intensity.

9. The method for suppressing the gold-stealing effect of organocarbon gold ores during cyanide leaching according to claim 1 or 8, characterized in that, In step (3), the amount of activated carbon added is 20~40 g / L, and the stirring intensity is 0.5~1.0 kW / m. 3 The adsorption time is 12-28 hours.

10. The method for suppressing the gold-stealing effect of organocarbon gold ores during cyanide leaching according to claim 1, characterized in that, In step (1), the carbonaceous gold ore includes at least one of the following: Carlin-type gold ore, micro-disseminated carbonaceous gold ore, black shale-type gold ore, carbonaceous sedimentary gold ore, or graphite-type gold ore.

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