Flotation pre-treatment reagent system and method of recovering gold from gold-containing spent fly ash

Abstract

The application provides a flotation pretreatment reagent system and a method for recovering gold from gold-containing waste soot, and belongs to the technical field of hydrometallurgy. The application designs a reagent system with multiple reagents in cooperation, constructs a gold recovery system of "catalytic oxidation-bridging anchoring-hydrophobic flotation", and successfully realizes the strategy change from passive inhibition of carbon adsorption to active separation of carbon carrier. Unlike the traditional method which only tries to passivate the adsorption activity of carbon, the present scheme converts the "gold-robber carbon" which interferes with gold recovery into a flotation carrier which is easy to separate through precise reagent cooperation, and fundamentally solves the problem of interference of carbon with cyanide gold extraction. 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 subsequent cyanide leaching, greatly reduces the reagent consumption, but also shows the important technical value of realizing process innovation through molecular level cooperative design.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, specifically to a flotation pretreatment reagent system and a method for recovering gold from gold-containing waste flue dust. Background Technology

[0002] In the gold smelting industry, pyrometallurgical processes generate large quantities of carbonaceous waste ash when processing gold-bearing materials. This ash typically contains a considerable amount of recoverable gold, which has significant economic value. Currently, wet cyanide leaching is the preferred process for recovering this type of gold. However, the unburned active carbonaceous components in the ash preferentially adsorb gold-cyanide complexes in the cyanide system, causing a severe "gold robbery" phenomenon. This leads to a sharp decline in gold recovery rates, directly resulting in resource waste and economic losses.

[0003] To address this industry challenge, existing technologies primarily employ calcination or chemical passivation. Calcination removes carbonaceous components through high-temperature oxidation, but suffers from high energy consumption, large equipment investment, potential release of harmful gases, and the risk of sintering and encapsulating gold particles. Chemical passivation attempts to cover the active sites of carbon with various inhibitors, but it generally suffers from unstable passivation effects, high reagent consumption, poor selectivity in complex systems, and essentially still retains carbon within the system, failing to fundamentally eliminate its potential adsorption capacity. Summary of the Invention

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

[0005] In a first aspect, this application provides a flotation pretreatment reagent system comprising hydrogen peroxide, copper sulfate pentahydrate, and hexadecyltrimethylammonium bromide.

[0006] In the technical solution of this application embodiment, 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, by micro-etching, they destroy the crystal structure of carbon, 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 negative charge and creating more suitable interface conditions for subsequent processing. Based on this, a cationic surfactant... Hexaalkyltrimethylammonium bromide (CTAB) achieves key bridging and hydrophobication functions through a unique dual-action mechanism. The cationic head group of CTAB generates strong electrostatic adsorption with the negatively charged carbon surface on the one hand, and forms coordination bonds with pre-anchored copper species on the other hand. 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. At the same time, through hydrophobic association, it promotes the aggregation of fine carbon particles into large particles that are easy to float, creating ideal conditions for subsequent separation.

[0007] Secondly, this application provides a method for recovering gold from gold-containing waste flue gas using a flotation pretreatment reagent system, comprising the following steps:

[0008] S1. Grind the gold-containing waste flue ash into a fine sample;

[0009] 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.

[0010] S3. Add hexadecyltrimethylammonium bromide to the catalytically oxidized modified slurry and stir thoroughly to obtain a flotation pretreated slurry;

[0011] 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;

[0012] S5. The flotation tailings are subjected to cyanide leaching to obtain a gold-bearing solution and solid residue.

[0013] In the technical solution of this application embodiment, a method for recovering gold from gold-containing waste flue gas is designed through 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 carbon supports. Unlike traditional methods that only attempt to passivate the adsorption activity of carbon, this solution, 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 are efficiently separated by flotation due to their excellent hydrophobic properties, while gold, not being hydrophobized, is enriched in the tailings. 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 achieving process innovation through molecular-level synergistic design.

[0014] In some embodiments, in step S2, the specific pH value is 10-12.

[0015] In this embodiment, by adjusting the slurry to a specific pH value, conditions are created for subsequent reactions. If the pH is too low, Cu... 2+ It exists in the form of free ions, and its adsorption and bridging abilities are very weak; if the pH is too high (>12), it may form soluble [Cu(OH)4]. 2- The ions will also leave the carbon surface and lose their bridging effect; in addition, the strongly alkaline environment is compatible with the conditions required for subsequent cyanide leaching, avoiding the cost and operational complexity caused by frequent pH adjustments.

[0016] In some embodiments, in step S2, the concentration of copper sulfate pentahydrate in the slurry is 10~40 g / L.

[0017] 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 at the active sites of carbon. This not only provides catalytic reaction sites for hydrogen peroxide, but also guides it to generate highly active free radicals, creating conditions for subsequent processing.

[0018] In some embodiments, in step S2, the volume of the hydrogen peroxide solution accounts for 5-10% of the volume of the water.

[0019] In this embodiment, hydrogen peroxide can be anchored at 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 carbon surface, and at the same time destroy the crystal structure of carbon through micro-etching, significantly reducing its adsorption capacity. This process not only eliminates the gold-robbing property of carbon, but also generates more carboxyl groups on the carbon surface to enhance its negative charge, creating more suitable interface conditions for subsequent processing.

[0020] In some embodiments, in step S3, the mass of the hexadecyltrimethylammonium bromide accounts for 0.05 to 0.2% of the mass of the gold-containing waste flue dust.

[0021] In this embodiment, the cationic surfactant CTAB achieves key bridging and hydrophobication functions through a unique dual-action mechanism. The cationic head group of CTAB exhibits strong electrostatic adsorption with the negatively charged carbon surface on one hand, and coordinate bonding with pre-anchored copper species on the other. This dual-bonding mode constructs a robust "carbon-copper-CTAB" ternary composite structure. Thanks to this strong anchoring effect, the hydrophobic long chains of CTAB are tightly packed, 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.

[0022] In some embodiments, step S4 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 off bubbles every 5 seconds, adding water every 30 seconds, and repeating the process.

[0023] In this embodiment, the modified carbon aggregates are efficiently separated by flotation due to their excellent hydrophobic properties, while gold is enriched in the tailings because it is not hydrophobized. This fundamentally solves the problem of carbon interference in cyanide gold extraction and realizes a strategy shift from passively inhibiting carbon adsorption to actively separating carbon carriers.

[0024] In some embodiments, step S5 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.

[0025] In this embodiment, under alkaline conditions, the chemical equilibrium of dissolved gold is greatly shifted to the left during cyanide leaching, effectively inhibiting the formation of HCN. Since the pH value of the pulp has been adjusted to a suitable range during the aforementioned flotation process, no further pH adjustment is required during the leaching process, which can achieve a good leaching effect, saving reagents while ensuring safe production.

[0026] In some embodiments, in step S2, the concentration of the slurry is 20-40%.

[0027] In this embodiment, the slurry concentration is the physical basis of the entire "catalytic oxidation-hydrophobic flotation" process. By regulating the fluid force field, it ensures that the preceding chemical reaction and the subsequent physical separation process can be carried out efficiently and stably.

[0028] In some embodiments, in step S1, the finely ground sample has a particle size of less than 200 mesh accounting for more than 99%.

[0029] In this embodiment, the flue ash is ground to a specific fineness to facilitate subsequent processing.

[0030] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0032] Figure 1 This is a mechanism diagram of the flotation pretreatment reagent system in the embodiments of this application. Detailed Implementation

[0033] The embodiments of the technical solution of this application are described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the scope of protection of this application.

[0034] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0035] To address the problems of low recovery efficiency, high reagent consumption, poor selectivity, and severe pollution associated with existing methods for recovering gold from gold-containing waste flue dust, this application provides a flotation pretreatment reagent system and a method for recovering gold from gold-containing waste flue dust. By designing the 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 on the carbon surface where gold is adsorbed. 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 processing. Based on this, the cationic surfactant hexadecyltrimethylammonium bromide (CTAB) achieves key bridging and hydrophobicity through a unique dual-action mechanism. The cation head group of CTAB exhibits strong electrostatic adsorption on the negatively charged carbon surface and coordinate 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.

[0036] In a first aspect, this application provides a flotation pretreatment reagent system comprising hydrogen peroxide, copper sulfate pentahydrate, and hexadecyltrimethylammonium bromide.

[0037] In the technical solution of this application embodiment, 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, by micro-etching, they destroy the crystal structure of carbon, 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 negative charge and creating more suitable interface conditions for subsequent processing. Based on this, a cationic surfactant... Hexaalkyltrimethylammonium bromide (CTAB) achieves key bridging and hydrophobication functions through a unique dual-action mechanism. The cationic head group of CTAB generates strong electrostatic adsorption with the negatively charged carbon surface on the one hand, and forms coordination bonds with pre-anchored copper species on the other hand. 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. At the same time, through hydrophobic association, it promotes the aggregation of fine carbon particles into large particles that are easy to float, creating ideal conditions for subsequent separation.

[0038] Secondly, this application provides a method for recovering gold from gold-containing waste flue gas using a flotation pretreatment reagent system, comprising the following steps:

[0039] S1. Grind the gold-containing waste flue ash into a fine sample;

[0040] 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.

[0041] S3. Add hexadecyltrimethylammonium bromide to the catalytically oxidized modified slurry and stir thoroughly to obtain a flotation pretreated slurry;

[0042] 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;

[0043] S5. The flotation tailings are subjected to cyanide leaching to obtain a gold-bearing solution and solid residue.

[0044] In the technical solution of this application embodiment, a method for recovering gold from gold-containing waste flue gas is designed through 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 carbon supports. Unlike traditional methods that only attempt to passivate the adsorption activity of carbon, this solution, 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 are efficiently separated by flotation due to their excellent hydrophobic properties, while gold, not being hydrophobized, is enriched in the tailings. 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 achieving process innovation through molecular-level synergistic design.

[0045] Furthermore, in some embodiments, in step S2, the specific pH value is 10-12.

[0046] In the technical solution of this application embodiment, by adjusting the slurry to a specific pH value, conditions are created for subsequent reactions. If the pH is too low, Cu... 2+ It exists in the form of free ions, and its adsorption and bridging abilities are very weak; if the pH is too high (>12), it may form soluble [Cu(OH)4]. 2- The ions will also leave the carbon surface and lose their bridging effect; in addition, the strongly alkaline environment is compatible with the conditions required for subsequent cyanide leaching, avoiding the cost and operational complexity caused by frequent pH adjustments.

[0047] Furthermore, in some embodiments, in step S2, the concentration of copper sulfate pentahydrate in the slurry is 10~40 g / L.

[0048] In the technical solution of this application 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 at the active sites of carbon. This not only provides catalytic reaction sites for hydrogen peroxide, but also guides it to generate highly active free radicals, creating conditions for subsequent processing.

[0049] Furthermore, in some embodiments, in step S2, the volume of the hydrogen peroxide solution accounts for 5-10% of the volume of water.

[0050] In the technical solution of this application embodiment, hydrogen peroxide can be anchored at the above-mentioned catalytic reaction site 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 carbon surface, and at the same time destroy the crystal structure of carbon through micro-etching, significantly reducing its adsorption capacity. This process not only eliminates the gold-robbing property of carbon, but also generates more carboxyl groups on the carbon surface to enhance the negative charge, creating more suitable interface conditions for subsequent processing.

[0051] Furthermore, in some embodiments, the reaction time in step S2 is 2 hours.

[0052] Furthermore, in some embodiments, in step S3, the mass of the hexadecyltrimethylammonium bromide accounts for 0.05 to 0.2% of the mass of the gold-containing waste flue dust.

[0053] In the technical solution of this application embodiment, the cationic surfactant CTAB achieves key bridging and hydrophobication functions through a unique dual-action mechanism. The cationic head group of CTAB generates strong electrostatic adsorption with the negatively charged carbon surface on one hand, and forms coordination bonds with pre-anchored copper species on the other. This dual-bonding mode constructs a robust "carbon-copper-CTAB" ternary composite structure. Thanks to this strong anchoring effect, the hydrophobic long chains of CTAB are tightly arranged, forming a dense monomolecular hydrophobic layer on the particle surface. Simultaneously, through hydrophobic association, it promotes the aggregation of fine carbon particles into larger particles that are easily floated, creating ideal conditions for subsequent separation.

[0054] Furthermore, in some embodiments, step S4 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 off bubbles every 5 seconds, adding water every 30 seconds, and repeating the process.

[0055] In the technical solution of this application embodiment, the modified carbon agglomerates are efficiently separated by flotation due to their excellent hydrophobic properties, while gold is enriched in the tailings because it is not hydrophobized. This fundamentally solves the problem of carbon interference with cyanide gold extraction and realizes a strategy shift from passively inhibiting carbon adsorption to actively separating carbon carriers.

[0056] Furthermore, in some embodiments, step S5 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.

[0057] In the technical solution of this application embodiment, under alkaline conditions in cyanide gold leaching, the chemical equilibrium of dissolved gold will be greatly shifted to the left, effectively inhibiting the formation of HCN. The pH value of the pulp has been adjusted to a suitable range during the aforementioned flotation process, so there is no need to adjust the pH value again during the leaching process, which can also achieve a good leaching effect, saving reagents while ensuring safe production.

[0058] Furthermore, in some embodiments, in step S2, the concentration of the slurry is 20-40%.

[0059] In the technical solution of this application embodiment, a pulp concentration of 20-40% is the physical basis of the entire "catalytic oxidation-hydrophobic flotation" process. By regulating the fluid force field, it ensures that the preceding chemical reaction and the subsequent physical separation process can be carried out efficiently and stably.

[0060] Furthermore, in some embodiments, in step S1, the ground sample has a particle size of less than 200 mesh accounting for more than 99%.

[0061] In the technical solution of this application embodiment, the flue ash is ground to a specific fineness to facilitate subsequent processing.

[0062] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0063] Example 1

[0064] Example 1 provides a method for recovering gold from gold-containing waste flue gas using a flotation pretreatment reagent system, specifically including the following steps:

[0065] (1) Grind the gold-containing waste flue dust produced by pyrometallurgical refining to a particle size of less than 200 mesh, accounting for 99%, to obtain a finely ground sample;

[0066] (2) Add water to the finely ground sample to prepare a slurry with a concentration of 33%. Then adjust the pH of the slurry to 10.50. Add 20 g / L of copper sulfate pentahydrate while stirring. Then add hydrogen peroxide solution accounting for 8% of the water volume. React for 2 hours to obtain the slurry after catalytic oxidation modification.

[0067] (3) Add 0.1% of the mass of gold-containing waste flue dust to the catalytically oxidized slurry and stir for 30 min to obtain the flotation pretreatment slurry;

[0068] (4) Adjust the pH of the flotation pretreatment slurry to 10.50, add 50 g / t of kerosene, add 10 g / t of frother after 1 min, open the air valve to introduce air after 3 min, scrape the bubbles once every 5 s, add water once every 30 s, repeat the process to obtain flotation tailings and floating carbonaceous components.

[0069] (5) Add 5 kg / t of sodium cyanide to the flotation tailings and leach for 24 h at pH 10.50 to obtain gold-containing solution and solid residue.

[0070] The gold content in the solid residues of each embodiment and comparative example was determined by fire assay, and the testing and analysis methods were in accordance with GB / T 7739 "Chemical Analysis Methods for Gold Concentrates". Therefore, the gold leaching rate η was...

[0071]

[0072] 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.

[0073] 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.

[0074] Examples 2-3 and Comparative Examples 1-2

[0075] 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.

[0076] Table 1. Amount of copper sulfate pentahydrate added and gold leaching rate in Examples 1-3 and Comparative Examples 1-2

[0077]

[0078] 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.

[0079] Examples 4-5 and Comparative Examples 3-4

[0080] 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.

[0081] 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.

[0082]

[0083] 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.

[0084] Examples 6-7 and Comparative Examples 5-6

[0085] 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.

[0086] Table 3 shows the mass fraction of CTAB and the gold leaching rate in Examples 1, 6-7, and Comparative Examples 5-6.

[0087]

[0088] 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.

[0089] Examples 8-9 and Comparative Examples 7-8

[0090] 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.

[0091] Table 4 shows the pH value and gold leaching rate in step (2) of Examples 1, 8-9, and Comparative Examples 7-8.

[0092]

[0093] 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.

[0094] Examples 10-11 and Comparative Examples 9-10

[0095] 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.

[0096] Table 5. Concentration of slurry and gold leaching rate in Examples 1, 10-11 and Comparative Examples 9-10.

[0097]

[0098] 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.

[0099] 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.

[0100] 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 method for recovering gold from gold-containing waste flue gas using a flotation pretreatment reagent system, characterized in that, The process employs a flotation pretreatment reagent system, including 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; The flotation pretreatment reagent system includes hydrogen peroxide, copper sulfate pentahydrate, and hexadecyltrimethylammonium bromide.

2. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 1, characterized in that, In step S2, the specific pH value is 10~12.

3. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 1, characterized in that, In step S2, the concentration of copper sulfate pentahydrate in the slurry is 10~40 g / L.

4. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 1, characterized in that, In step S2, the volume of the hydrogen peroxide solution accounts for 5-10% of the volume of the water.

5. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 1, 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.

6. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 1, 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.

7. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 1, 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.

8. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 1, characterized in that, In step S2, the concentration of the slurry is 20-40%.

9. The method for recovering gold from gold-containing waste flue gas using the flotation pretreatment reagent system according to claim 1, 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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