Flotation pretreatment reagent system and method for treating gold-bearing waste soot and recovering gold by using flotation pretreatment reagent system

Abstract

The invention provides a flotation pretreatment reagent system and a method for treating gold-bearing waste soot and recycling gold through the flotation pretreatment reagent system, and belongs to the technical field of hydrometallurgy. According to the invention, a multi-agent synergistic agent system is designed, a gold recovery system of'catalytic oxidation-bridging anchoring-hydrophobic flotation 'is constructed, and strategy transformation from passive inhibition of carbon adsorption to active separation of a carbon carrier is successfully realized. Compared with a traditional method which only tries to passivate the adsorption activity of carbon, the method has the advantages that gold-robbing carbon interfering with gold recovery is converted into a flotation carrier easy to separate through accurate reagent matching, and the problem that carbonaceous interferes with cyaniding gold extraction is fundamentally solved. The modified carbon agglomerates are subjected to efficient flotation separation due to the excellent hydrophobic characteristic, and the gold is enriched in the tailings due to the fact that the gold is not hydrophobized. According to the method, the gold recovery rate of follow-up cyanidation leaching is remarkably increased, the agent consumption is greatly reduced, and the important technical value of achieving technological process innovation through molecular-level collaborative design is shown.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrometallurgy, and particularly relates to a flotation pretreatment reagent system and a method for recovering gold from gold-containing waste soot. BACKGROUND

[0002] In the gold smelting industry, a large amount of waste soot rich in carbon is produced when a pyrometallurgical process is used to treat gold-containing materials. The soot usually contains considerable recoverable gold, which has important economic value. At present, wet cyanide leaching is the preferred process for recovering such gold, however, the unburned active carbon components in the soot will preferentially adsorb gold cyanide complexes in the cyanide system, causing a serious "gold robbing" phenomenon, which leads to a sharp decrease in gold recovery, directly causing resource waste and economic losses.

[0003] In view of this industry problem, the existing technology mainly uses roasting or chemical passivation methods for treatment. The roasting method removes carbon components by high-temperature oxidation, but has problems such as high energy consumption, large equipment investment, possible volatilization of harmful gases, and sintering of gold particles. The chemical passivation method attempts to use various inhibitors to cover the active sites of carbon, but it generally has the disadvantages of unstable passivation effect, large reagent consumption, poor selectivity in complex systems, and essentially still retains carbon in the system, which does not fundamentally eliminate its potential adsorption capacity. SUMMARY

[0004] In view of the technical problems in the background art, the present application provides a flotation pretreatment reagent system and a method for recovering gold from gold-containing waste soot, which aims to solve the problems of low recovery efficiency, large reagent consumption, poor selectivity, and serious pollution of the existing methods for recovering gold from gold-containing waste soot.

[0005] In a first aspect, the present application provides a flotation pretreatment reagent system, which comprises hydrogen peroxide, copper sulfate pentahydrate, and cetyltrimethylammonium bromide.

[0006] In the technical scheme of the embodiment of the application, by designing a flotation pretreatment reagent system, copper hydroxide colloid formed by copper ions in an alkaline environment is preferentially anchored on active sites of carbon, not only providing a catalytic reaction site for hydrogen peroxide, but also guiding the generation of highly active radicals. These radicals can accurately oxidize functional groups of gold adsorbed on the surface of carbon, and at the same time, destroy the crystal structure of carbon through micro-etching, significantly reducing the adsorption capacity. This process not only eliminates the gold-robbing characteristics of carbon, but also generates more carboxyl groups on the surface of carbon, thereby enhancing the negative charge and creating more suitable interface conditions for subsequent processing. On this basis, the cationic surfactant cetyltrimethylammonium bromide (CTAB) realizes the key bridging and hydrophobization functions through a unique dual-action mechanism. The cationic head group of CTAB is strongly electrostatically adsorbed on the negatively charged surface of carbon, and at the same time forms a coordination bond with the pre-anchored copper species. This dual bonding mode constructs a firm "carbon-copper-CTAB" ternary composite structure. This strong anchoring effect allows the hydrophobic long chain of CTAB to closely arrange and form a dense monomolecular hydrophobic layer on the surface of the particles, and at the same time, through hydrophobic association, small carbon particles are agglomerated into large particles that are easy to float, creating ideal conditions for subsequent separation.

[0007] In a second aspect, the application provides a method for recovering gold from gold-containing waste soot by using a flotation pretreatment reagent system, comprising the following steps: S1. finely grinding the gold-containing waste soot to obtain a finely ground sample; S2. adding water to the finely ground sample to prepare a slurry, then adjusting the slurry to a specific pH value, and then adding copper sulfate pentahydrate and hydrogen peroxide solution under stirring to obtain a catalytically oxidized and modified slurry; S3. adding cetyltrimethylammonium bromide to the catalytically oxidized and modified slurry and stirring thoroughly to obtain a flotation pretreatment slurry; S4. performing flotation on the flotation pretreatment slurry under the specific pH value condition of step S2 to obtain flotation tailings and floated carbonaceous components; S5. performing cyanide leaching on the flotation tailings to obtain a gold-containing pregnant solution and solid residues.

[0008] In the technical scheme of the embodiment of the application, a method for recovering gold from waste soot containing gold is designed through a flotation pretreatment reagent system, and a gold recovery system of "catalytic oxidation-bridging anchoring-hydrophobic flotation" is constructed through multiple reagents. The strategy is successfully changed from passive inhibition of carbon adsorption to active separation of carbon carriers. Unlike the traditional method which only attempts to passivate the adsorption activity of carbon, the present scheme converts the "gold-robbing carbon" that interferes with gold recovery into a flotation carrier that is easy to separate through precise reagent matching, thereby fundamentally solving the interference problem of carbon on cyanide gold leaching. The modified carbon clusters are efficiently separated by flotation due to their excellent hydrophobic properties, and gold is enriched in the tailings because it is not hydrophobized. This not only significantly improves the gold recovery rate of cyanide leaching, but also greatly reduces reagent consumption, and further demonstrates the important technical value of process innovation through molecular-level collaborative design.

[0009] In some embodiments, in step S2, the specific pH value is 10-12.

[0010] In this embodiment, by adjusting the pulp to a specific pH value, conditions are created for subsequent reactions. If the pH is too low, Cu 2+ exists in the form of free ions, and its adsorption and bridging ability is weak; if the pH is too high (>12), soluble [Cu(OH)4] 2- complex ions may be generated, which will also leave the carbon surface and lose the bridging effect; in addition, the strong alkaline environment is also compatible with the conditions required for subsequent cyanide leaching, avoiding the cost and operational complexity brought by frequent pH adjustment.

[0011] In some embodiments, in step S2, the concentration of copper sulfate pentahydrate in the pulp is 10-40 g / L.

[0012] In this embodiment, copper sulfate pentahydrate is added in an alkaline environment. Copper sulfate pentahydrate acts as a catalyst, and copper ions form copper hydroxide colloid, which is first anchored on the active sites of carbon, not only providing catalytic reaction sites for hydrogen peroxide, but also guiding the generation of highly active free radicals to create conditions for subsequent processing.

[0013] In some embodiments, in step S2, the volume of the hydrogen peroxide solution accounts for 5-10% of the volume of water.

[0014] In this embodiment, hydrogen peroxide can be anchored on the above-mentioned catalytic reaction sites and generate highly active free radicals under the guidance of copper sulfate pentahydrate. These free radicals can precisely oxidize the functional groups of gold adsorbed on the surface of carbon, and at the same time, they can significantly reduce the adsorption capacity of carbon by micro-etching the crystal structure of carbon. This process not only eliminates the gold-robbing characteristics of carbon, but also generates more carboxyl groups on the surface of carbon to enhance the negative charge, thereby creating more suitable interface conditions for subsequent processing.

[0015] In some embodiments, in step S3, the mass of the cetyltrimethylammonium bromide accounts for 0.05-0.2% of the mass of the gold-containing waste soot.

[0016] In this embodiment, the cationic surfactant CTAB realizes the key bridging and hydrophobization functions through a unique dual-action mechanism. The cationic head group of CTAB produces strong electrostatic adsorption with the negatively charged carbon surface, and forms coordination bonding with the pre-anchored copper species. This dual-bonding mode constructs a firm "carbon-copper-CTAB" ternary composite structure. Thanks to this strong anchoring effect, the hydrophobic long chains of CTAB can be closely arranged to form a dense monomolecular hydrophobic layer on the particle surface, and at the same time, through hydrophobic interaction, small carbon particles are aggregated into large particles that are easy to float, creating ideal conditions for subsequent separation.

[0017] In some embodiments, in step S4, the flotation specifically includes the following steps: adding 50 g / t of kerosene to the flotation pretreated ore slurry, after 1 min, adding 10 g / t of a foaming agent, after 3 min, opening the air inlet valve to introduce air, scraping the foam every 5 s, and supplementing water every 30 s, repeating the process.

[0018] In this embodiment, through flotation, the modified carbon aggregates are efficiently separated due to their excellent hydrophobic properties, and gold is enriched in the tailings because it is not hydrophobized, thus fundamentally solving the problem of carbon interference in cyanide gold extraction and realizing a strategic change from passive inhibition of carbon adsorption to active separation of carbon carriers.

[0019] In some embodiments, in step S5, the cyanide leaching specifically includes the following steps: adding 5 kg / t of sodium cyanide to the flotation tailings, and leaching for 24 h at a pH value of 10-12.

[0020] In this embodiment, in the cyanide leaching of gold, the alkaline conditions greatly promote the chemical equilibrium of dissolved gold to move to the left, effectively inhibiting the generation of HCN. In the aforementioned flotation process, the pH value of the ore slurry has been adjusted to an appropriate range, so there is no need to adjust the pH value again during the leaching process, which not only saves reagents but also ensures the premise of safe production.

[0021] In some embodiments, in step S2, the concentration of the ore slurry is 20-40%.

[0022] In this embodiment, the ore slurry concentration is the physical basis of the entire "catalytic oxidation-hydrophobic flotation" process, which ensures that both the preceding chemical reaction and the subsequent physical separation process can be efficiently and stably carried out by regulating the fluid force field.

[0023] In some embodiments, in step S1, the ground sample has a particle size of less than 200 mesh, and more than 99% of the sample is less than 200 mesh.

[0024] In this embodiment, the soot is ground to a specific fineness, which facilitates subsequent processing.

[0025] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, the content of the specification can be implemented, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the present application, the drawings used in the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creating any creative labor.

[0027] Figure 1 Mechanism diagram of the effect of the flotation pretreatment reagent system in the embodiments of the present application. DETAILED DESCRIPTION

[0028] The embodiments of the technical solutions of the present application will be described in detail below. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0029] In this document, referring to "embodiments" means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily mean that the same embodiment is referred to, nor is it independent or alternative to other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0030] In order to solve the problems of low recovery efficiency, large reagent consumption, poor selectivity and serious pollution in the existing method for recovering gold from gold-containing waste soot, the application provides a flotation pretreatment reagent system and a method for recovering gold from gold-containing waste soot. By designing the flotation pretreatment reagent system, in an alkaline environment, copper hydroxide colloid formed by copper ions is preferentially anchored on the active sites of carbon, not only providing a catalytic reaction site for hydrogen peroxide, but also guiding the generation of highly active free radicals. These free radicals can accurately oxidize the functional groups of gold adsorbed on the surface of carbon, and at the same time, through micro-etching, the crystal structure of carbon is destroyed, significantly reducing its adsorption capacity. This process not only eliminates the gold-robbing characteristics of carbon, but also generates more carboxyl groups on the surface of carbon, thereby enhancing the negative charge and creating more suitable interface conditions for subsequent processing. On this basis, the cationic surfactant cetyltrimethylammonium bromide (CTAB) realizes the key bridging and hydrophobic functions through a unique dual-action mechanism. The cationic head group of CTAB is strongly electrostatically adsorbed on the negatively charged surface of carbon, and at the same time, forms a coordination bond with the pre-anchored copper species. This dual bonding mode constructs a firm "carbon-copper-CTAB" ternary composite structure. The strong anchoring effect allows the hydrophobic long chain of CTAB to closely arrange and form a dense monomolecular hydrophobic layer on the surface of the particles, and at the same time, through hydrophobic interaction, the small carbon particles are aggregated into large particles that are easy to float, creating ideal conditions for subsequent separation. In addition, through the flotation pretreatment reagent system, a method for recovering gold from gold-containing waste soot is designed, and a "catalytic oxidation-bridging anchoring-hydrophobic flotation" gold recovery system is constructed by the synergistic effect of multiple reagents. The strategy change from passive inhibition of carbon adsorption to active separation of carbon carriers is successfully realized. Unlike traditional methods that only attempt to passivate the adsorption activity of carbon, this scheme accurately matches the reagents to convert the "gold-robbing carbon" that interferes with gold recovery into a floatation carrier that is easy to separate, fundamentally solving the problem of carbon interference with cyanide gold extraction. The modified carbon aggregates are efficiently separated by flotation due to their excellent hydrophobic properties, and gold is enriched in the tailings due to the lack of hydrophobicity. This not only significantly improves the gold recovery rate of cyanide leaching and greatly reduces reagent consumption, but also demonstrates the important technical value of process innovation through molecular-level synergistic design.

[0031] In a first aspect, the application provides a flotation pretreatment reagent system, which comprises hydrogen peroxide, copper sulfate pentahydrate and cetyltrimethylammonium bromide.

[0032] In the technical scheme of the embodiment of the application, by designing a flotation pretreatment reagent system, copper hydroxide colloid formed by copper ions in an alkaline environment is preferentially anchored on active sites of carbon, not only providing a catalytic reaction site for hydrogen peroxide, but also guiding the generation of highly active radicals. These radicals can accurately oxidize functional groups of gold adsorbed on the surface of carbon, and at the same time, destroy the crystal structure of carbon through micro-etching, significantly reducing the adsorption capacity. This process not only eliminates the gold-robbing characteristics of carbon, but also generates more carboxyl groups on the surface of carbon, thereby enhancing the negative charge and creating more suitable interface conditions for subsequent processing. On this basis, the cationic surfactant cetyltrimethylammonium bromide (CTAB) realizes the key bridging and hydrophobization functions through a unique dual-action mechanism. The cationic head group of CTAB is strongly electrostatically adsorbed on the negatively charged surface of carbon, and at the same time forms a coordination bond with the pre-anchored copper species. This dual bonding mode constructs a firm "carbon-copper-CTAB" ternary composite structure. The strong anchoring effect allows the hydrophobic long chain of CTAB to closely arrange and form a dense monomolecular hydrophobic layer on the surface of the particles, and at the same time, through hydrophobic association, small carbon particles are agglomerated into large particles that are easy to float, creating ideal conditions for subsequent separation.

[0033] In a second aspect, the application provides a method for recovering gold from gold-containing waste soot by using a flotation pretreatment reagent system, comprising the following steps: S1. finely grinding the gold-containing waste soot to obtain a finely ground sample; S2. adding water to the finely ground sample to prepare a slurry, then adjusting the slurry to a specific pH value, and then adding copper sulfate pentahydrate and hydrogen peroxide solution under stirring to obtain a catalytically oxidized and modified slurry; S3. adding cetyltrimethylammonium bromide to the catalytically oxidized and modified slurry and stirring thoroughly to obtain a flotation pretreatment slurry; S4. performing flotation on the flotation pretreatment slurry under the specific pH value condition of step S2 to obtain flotation tailings and floated carbonaceous components; S5. performing cyanide leaching on the flotation tailings to obtain a gold-containing pregnant solution and solid residues.

[0034] In the technical scheme of the embodiment of the application, a method for recovering gold from waste soot containing gold is designed through a flotation pretreatment reagent system, and a gold recovery system of "catalytic oxidation-bridging anchoring-hydrophobic flotation" is constructed through multiple reagents. The strategy is successfully changed from passive inhibition of carbon adsorption to active separation of carbon carriers. Unlike the traditional method which only attempts to passivate the adsorption activity of carbon, the present scheme converts the "gold-robbing carbon" that interferes with gold recovery into a flotation carrier that is easy to separate through precise reagent coordination, thereby fundamentally solving the problem of interference of carbon with cyanide gold leaching. The modified carbon clusters are efficiently separated by flotation due to their excellent hydrophobic properties, and gold is enriched in the tailings because it is not hydrophobized. This not only significantly improves the gold recovery rate of cyanide leaching, but also greatly reduces reagent consumption, and further demonstrates the important technical value of process innovation through molecular-level collaborative design.

[0035] Further, in some embodiments, in step S2, the specific pH value is 10-12.

[0036] In the technical scheme of the embodiment of the application, the pH of the ore slurry is adjusted to a specific value to create conditions for subsequent reactions. If the pH is too low, Cu 2+ exists in the form of free ions, and its adsorption and bridging ability is weak; if the pH is too high (>12), soluble [Cu(OH)4] 2- complex ions may be generated, which will also leave the carbon surface and lose the bridging effect; in addition, a strong alkaline environment is also compatible with the conditions required for subsequent cyanide leaching, avoiding the cost and operational complexity caused by frequent pH adjustment.

[0037] Further, in some embodiments, in step S2, the concentration of copper sulfate pentahydrate in the ore slurry is 10-40 g / L.

[0038] In the technical scheme of the embodiment of the application, copper sulfate pentahydrate is added in an alkaline environment. Copper sulfate pentahydrate acts as a catalyst, and copper ions form copper hydroxide colloid, which is first anchored on the active sites of carbon, not only providing catalytic reaction sites for hydrogen peroxide, but also guiding the generation of highly active free radicals to create conditions for subsequent treatment.

[0039] Further, in some embodiments, in step S2, the volume of the hydrogen peroxide solution accounts for 5-10% of the volume of water.

[0040] In the technical scheme of the embodiment of the application, hydrogen peroxide can be anchored on the above-mentioned catalytic reaction sites and generate highly active free radicals under the guidance of copper sulfate pentahydrate. These free radicals can accurately oxidize the functional groups of gold adsorbed on the surface of carbon, and at the same time, they can significantly reduce the adsorption capacity of carbon by micro-etching the crystal structure of carbon. This process not only eliminates the gold-robbing characteristics of carbon, but also generates more carboxyl groups on the surface of carbon to enhance the negative charge, thereby creating more suitable interface conditions for subsequent treatment.

[0041] Further, in some embodiments, in step S2, the reaction time is 2h.

[0042] Further, in some embodiments, in step S3, the mass of the cetyltrimethylammonium bromide accounts for 0.05-0.2% of the mass of the gold-containing waste soot.

[0043] In the technical scheme of the embodiments of the present application, the cationic surfactant CTAB realizes the key bridging and hydrophobization functions through a unique dual-action mechanism. The cationic head group of CTAB produces strong electrostatic adsorption with the negatively charged carbon surface, and forms a coordination bond with the pre-anchored copper species. This dual-bonding mode constructs a firm "carbon-copper-CTAB" ternary composite structure. Thanks to this strong anchoring effect, the hydrophobic long chains of CTAB can be closely arranged to form a dense monomolecular hydrophobic layer on the particle surface, and at the same time, through hydrophobic interaction, small carbon particles are aggregated into large particles that are easy to float, creating ideal conditions for subsequent separation.

[0044] Further, in some embodiments, in step S4, the flotation specifically includes the following steps: adding 50g / t of kerosene to the flotation pretreated ore slurry, after 1min, adding 10g / t of a foaming agent, after 3min, opening the air inlet valve to introduce air, scraping the foam every 5s, and supplementing water every 30s, repeating the process.

[0045] In the technical scheme of the embodiments of the present application, through flotation, the modified carbon aggregates are efficiently separated due to their excellent hydrophobic properties, and gold is enriched in the tailings because it is not hydrophobized, thus fundamentally solving the problem of carbon interference in cyanide gold extraction and realizing the strategic change from passive inhibition of carbon adsorption to active separation of carbon carriers.

[0046] Further, in some embodiments, in step S5, the cyanide leaching specifically includes the following steps: adding 5kg / t of sodium cyanide to the flotation tailings, and leaching for 24h at a pH value of 10-12.

[0047] In the technical scheme of the embodiments of the present application, in cyanide leaching of gold, the alkaline condition greatly promotes the chemical equilibrium of dissolved gold to move to the left, effectively inhibiting the generation of HCN. In the aforementioned flotation process, the pH value of the ore slurry has been adjusted to an appropriate range, so there is no need to adjust the pH value again during the leaching process, which not only saves reagents but also ensures the premise of safe production.

[0048] Further, in some embodiments, in step S2, the concentration of the ore slurry is 20-40%.

[0049] In the technical scheme of the embodiment of the present application, the slurry concentration of 20-40% is the physical basis of the whole "catalytic oxidation-hydrophobic flotation" process, which ensures that the previous chemical reaction and the subsequent physical separation process can be carried out efficiently and stably by regulating the fluid force field.

[0050] Further, in some embodiments, in step S1, the ground sample has a particle size of less than 200 mesh, accounting for more than 99%.

[0051] In the technical scheme of the embodiment of the present application, the soot is ground to a specific fineness, which facilitates subsequent processing.

[0052] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are used to explain the present application, and cannot be understood as limiting the present application. If the specific technology or condition is not specified in the embodiments, the technology or condition described in the literature in the art or according to the product manual is used. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained from the market.

[0053] Embodiment 1 Embodiment 1 provides a method for recovering gold from gold-containing waste soot by using a flotation pretreatment reagent system, which specifically comprises the following steps: (1) grinding the gold-containing waste soot generated by pyrogenic gold smelting to a particle size of less than 200 mesh, accounting for 99%, to obtain a ground sample; (2) adding water to the ground sample to prepare a slurry with a concentration of 33%, and then adjusting the pH value of the slurry to 10.50, under stirring, adding 20 g / L of copper sulfate pentahydrate, and then adding 8% of hydrogen peroxide solution based on the volume of water, and reacting for 2 h to obtain a catalytically oxidized modified slurry; (3) adding CTAB with a mass of 0.1% of the mass of the gold-containing waste soot to the catalytically oxidized modified slurry, and stirring for 30 min to obtain a flotation pretreatment slurry; (4) adjusting the pH value of the flotation pretreatment slurry to 10.50, adding 50 g / t of kerosene, and after 1 min, adding 10 g / t of a foaming agent, and after 3 min, opening the air inlet valve to introduce air, and scraping the foam every 5 s, and adding water every 30 s, and repeating the process to obtain a flotation tailings and an up-floating carbonaceous component; (5) adding 5 kg / t of sodium cyanide to the flotation tailings, and leaching for 24 h at a pH value of 10.50 to obtain a gold-containing pregnant solution and a solid residue.

[0054] The gold content in the solid residue in each embodiment and the comparative example is detected by fire assaying, and the test analysis method refers to GB / T 7739 "Gold Concentrate Chemical Analysis Method", and the gold leaching rate η is Where η represents the gold leaching rate, in %; m1 represents the mass of the original gold-containing waste flue ash, in g; β1 represents the grade of the gold-containing waste flue ash, in g / t; m2 represents the mass of the solid residue after leaching the gold-containing waste flue ash, in g; and β2 represents the grade of the solid residue after leaching the gold-containing waste flue ash, in g / t.

[0055] The gold concentration in the gold-containing solutions of each embodiment and comparative example was then detected by ICP-OES. The gold leaching rate test results of the two methods were compared, and data with a deviation of less than 1% between the two methods were considered valid. Finally, the gold leaching rate in each embodiment and comparative example was determined.

[0056] Examples 2-3 and Comparative Examples 1-2 Examples 2-3 and Comparative Examples 1-2 respectively provide a method for recovering gold from gold-containing waste flue gas using a flotation pretreatment reagent system. The difference between Example 1 and Example 2 is that the amount of copper sulfate pentahydrate added is different, as shown in Table 1. The other steps are roughly the same as in Example 1 and will not be repeated here.

[0057] Table 1. Amount of copper sulfate pentahydrate added and gold leaching rate in Examples 1-3 and Comparative Examples 1-2 As shown in Table 1, when the concentration of copper sulfate pentahydrate is between 10 and 40 g / L, the gold leaching rate is over 90%. However, when the concentration of copper sulfate pentahydrate increases to 50 g / L, the gold leaching rate decreases to 90%, indicating that excessive copper catalyst can inhibit the recovery process. The main reason is that excessively high copper concentration will form an excessively thick copper hydroxide coating on the surface of carbon particles. This not only blocks the pores of carbon, hindering the effective contact between the oxidant and the active sites, but also consumes a large number of cyanide ions in the subsequent cyanide leaching stage, competing with gold to form stable copper-cyanide complexes (such as [Cu(CN)3]²⁻ or [Cu(CN)4]³⁻), resulting in insufficient effective cyanide concentration. At the same time, some dissolved copper ions may also be directly adsorbed or deposited on the surface of gold particles, forming a passivation film that hinders the contact between gold and the cyanide solution, ultimately reducing the gold leaching efficiency.

[0058] Examples 4-5 and Comparative Examples 3-4 Examples 4-5 and Comparative Examples 3-4 respectively provide a method for recovering gold from gold-containing waste flue gas using a flotation pretreatment reagent system. The difference between Example 1 and Example 2 is that the amount of hydrogen peroxide solution added is different, as shown in Table 2. The other steps are roughly the same as in Example 1 and will not be described again here.

[0059] Table 2 shows the volume fraction of hydrogen peroxide solution and the gold leaching rate in Examples 1, 4-5, and Comparative Examples 3-4. Table 2 shows that there is a clear optimization window for the amount of hydrogen peroxide used to leach gold. When the volume fraction of hydrogen peroxide is in the range of 5-10%, the leaching rate of gold can be maintained above 90%. In Comparative Example 3 (4%), due to insufficient oxidant, the destruction of the "gold-robbing" active sites on the carbon surface was incomplete, and some carbon still retained adsorption capacity, resulting in a leaching rate of 86%. In Comparative Example 4 (12%), excessive hydrogen peroxide may cause severe ineffective decomposition, and the large number of bubbles generated will interfere with the stability of the subsequent flotation process. At the same time, the over-oxidized carbon surface may generate new functional groups that are not conducive to CTAB adsorption, which will destroy the stable formation of the "carbon-copper-CTAB" ternary complex, ultimately leading to a leaching rate of 89%. This indicates that controlling the concentration of hydrogen peroxide at an appropriate level is crucial to maintaining the efficient operation of the entire synergistic system.

[0060] Examples 6-7 and Comparative Examples 5-6 Examples 6-7 and Comparative Examples 5-6 respectively provide a method for recovering gold from gold-containing waste flue gas using a flotation pretreatment reagent system. The difference from Example 1 is that the amount of CTAB added is different, as shown in Table 3. The other steps are roughly the same as in Example 1, and will not be repeated here.

[0061] Table 3 shows the mass fraction of CTAB and the gold leaching rate in Examples 1, 6-7, and Comparative Examples 5-6. As shown in Table 3, although Comparative Example 6 still achieved a gold leaching rate of 94% with a CTAB mass fraction as high as 0.25%, demonstrating technical feasibility, its economic efficiency was significantly inferior to that of Example 1 (0.1%). This is mainly because CTAB is a relatively expensive cationic surfactant, and increasing its dosage would directly lead to a sharp increase in the cost of pretreatment reagents. Under the premise of achieving the same technical indicators (94% leaching rate), the amount of CTAB used in Comparative Example 6 was 2.5 times that of Example 1, which is uneconomical in actual industrial applications. The comparison results clearly show that controlling the mass fraction of CTAB within the preferred range of 0.05% to 0.2%, especially around 0.1%, is sufficient to achieve the best technical and economic efficiency while ensuring the ultimate recovery rate, avoiding excessive use of reagents and cost waste.

[0062] Examples 8-9 and Comparative Examples 7-8 Examples 8-9 and Comparative Examples 7-8 respectively provide a method for recovering gold from gold-containing waste flue gas using a flotation pretreatment reagent system. The difference between Example 1 and Example 2 is that the pH value in step (2) is different, as shown in Table 4. The other steps are roughly the same as in Example 1 and will not be repeated here.

[0063] Table 4 shows the pH value and gold leaching rate in step (2) of Examples 1, 8-9, and Comparative Examples 7-8. As shown in Table 4, when the pH value of the system increases to above 13, the gold leaching rate decreases significantly. This is mainly attributed to the ineffective decomposition of hydrogen peroxide in a strongly alkaline environment. Under high pH conditions, the chemical stability of H2O2 decreases sharply. Its decomposition pathway changes from the effective free radical generation reaction catalyzed by copper ions (generating ·OH with strong oxidizing properties) to spontaneous ineffective catalytic decomposition (2H2O2 → O2 + 2H2O). This process not only consumes a large amount of oxidant, but more importantly, it greatly weakens the directional oxidation and etching effect on the "gold-robbing" active sites (such as lactone groups, phenolic hydroxyl groups, etc.) on the carbon surface. The adsorption activity of carbon is not completely destroyed, which seriously affects the subsequent flotation separation and the final gold leaching effect.

[0064] Examples 10-11 and Comparative Examples 9-10 Examples 10-11 and Comparative Examples 9-10 respectively provide a method for recovering gold from gold-containing waste flue dust using a flotation pretreatment reagent system. The difference from Example 1 is that the concentration of the slurry is different, as shown in Table 5. The other steps are roughly the same as in Example 1 and will not be repeated here.

[0065] Table 5. Concentration of slurry and gold leaching rate in Examples 1, 10-11 and Comparative Examples 9-10. As shown in Table 5, the concentration of the slurry has a significant impact on the gold leaching effect. When the solid-liquid ratio is within the range of 20-40%, the gold leaching rate can be maintained above 90%. Although Comparative Example 7 (solid-liquid ratio of 10%) can achieve a leaching rate of 95%, the excessively low slurry concentration means that more water and energy are needed to process the same amount of material, resulting in low equipment efficiency and poor economic performance. In contrast, Comparative Example 7 (solid-liquid ratio of 55%) suffers from excessively high slurry concentration, which leads to hindered reagent diffusion, difficulty in bubble precipitation, and a sharp decline in flotation separation efficiency, resulting in a significant decrease in the leaching rate to 82%. This indicates that the present invention achieves the best balance between technical effectiveness and economic efficiency by optimizing the solid-liquid ratio of 20-40% while ensuring a high recovery rate.

[0066] In summary, this application provides a flotation pretreatment reagent system and a method for recovering gold from gold-containing waste flue gas. The mechanism of action of the flotation pretreatment reagent system is illustrated in the diagram below. Figure 1As shown, by designing a flotation pretreatment reagent system, in an alkaline environment, copper ions form copper hydroxide colloids that preferentially anchor on the active sites of carbon. This not only provides catalytic reaction sites for hydrogen peroxide but also guides the generation of highly active free radicals. These free radicals can precisely oxidize the functional groups of gold adsorbed on the carbon surface. Simultaneously, they destroy the crystal structure of carbon through micro-etching, significantly reducing its adsorption capacity. This process not only eliminates the gold-robbing properties of carbon but also generates more carboxyl groups on the carbon surface, thereby enhancing its electronegativity and creating more suitable interfacial conditions for subsequent treatment. Based on this, the cationic surfactant hexadecyltrimethylammonium bromide (CTAB) achieves key bridging and dehydrogenation through a unique dual-action mechanism. In terms of hydration, the cationic head group of CTAB exhibits strong electrostatic adsorption on the negatively charged carbon surface and simultaneously forms coordination bonds with pre-anchored copper species. This dual-bonding mode constructs a robust "carbon-copper-CTAB" ternary composite structure. This strong anchoring effect allows the hydrophobic long chains of CTAB to be tightly arranged, forming a dense monomolecular hydrophobic layer on the particle surface. Simultaneously, hydrophobic association promotes the aggregation of fine carbon particles into larger particles that are easily floated, creating ideal conditions for subsequent separation. Furthermore, a method for recovering gold from gold-containing waste flue gas was designed using a flotation pretreatment reagent system. Multiple reagents synergistically construct a gold recovery system of "catalytic oxidation-bridging anchoring-hydrophobic flotation." This successfully achieves a strategic shift from passively inhibiting carbon adsorption to actively separating the carbon support. Unlike traditional methods that merely attempt to passivate the adsorption activity of carbon, this scheme, through precise reagent formulation, transforms the "gold-robbing carbon" that interferes with gold recovery into an easily separable flotation support, fundamentally solving the problem of carbon interference in cyanide gold extraction. The modified carbon aggregates were efficiently separated by flotation due to their excellent hydrophobic properties, while gold, which remained unhydrophobic, was enriched in the tailings. This not only significantly improved the gold recovery rate of cyanide leaching and greatly reduced reagent consumption, but also demonstrated the important technological value of achieving process innovation through molecular-level co-design.

[0067] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A flotation pretreatment reagent system, characterized in that, The flotation pretreatment reagent system includes hydrogen peroxide, copper sulfate pentahydrate, and hexadecyltrimethylammonium bromide.

2. A method for recovering gold from gold-containing waste flue gas using a flotation pretreatment reagent system, characterized in that, The process using the flotation pretreatment reagent system described in claim 1 includes the following steps: S1. Grind the gold-containing waste flue ash into a fine sample; S2. Add water to the ground sample to prepare a slurry, then adjust the slurry to a specific pH value, add copper sulfate pentahydrate while stirring, then add hydrogen peroxide solution. After the reaction is complete, the catalytically oxidized slurry is obtained. S3. Add hexadecyltrimethylammonium bromide to the catalytically oxidized modified slurry and stir thoroughly to obtain a flotation pretreated slurry; S4. Under the specific pH conditions described in step S2, the pretreated flotation pulp is subjected to flotation to obtain flotation tailings and the floating carbonaceous components; S5. The flotation tailings are subjected to cyanide leaching to obtain a gold-bearing solution and solid residue.

3. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 2, characterized in that, In step S2, the specific pH value is 10~12.

4. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 2, characterized in that, In step S2, the concentration of copper sulfate pentahydrate in the slurry is 10~40 g / L.

5. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 2, characterized in that, In step S2, the volume of the hydrogen peroxide solution accounts for 5-10% of the volume of the water.

6. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 2, characterized in that, In step S3, the mass of the hexadecyltrimethylammonium bromide accounts for 0.05~0.2% of the mass of the gold-containing waste flue dust.

7. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 2, characterized in that, In step S4, the flotation specifically includes the following steps: adding 50 g / t of kerosene to the flotation pretreatment slurry, adding 10 g / t of frother after 1 minute, opening the air valve to introduce air after 3 minutes, scraping the bubbles every 5 seconds, adding water every 30 seconds, and repeating the process.

8. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 2, characterized in that, In step S5, the cyanide leaching specifically includes the following steps: adding 5 kg / t of sodium cyanide to the flotation tailings and leaching for 24 hours at a pH of 10-12.

9. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 2, characterized in that, In step S2, the concentration of the slurry is 20-40%.

10. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 2, characterized in that, In step S1, the finely ground sample has a particle size of less than 200 mesh accounting for more than 99%.

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