A cyanide tailings intensified gold extraction method based on magnetically controlled hydrothermal magnetization activation and manganese doping treatment

Abstract

This invention belongs to the field of hydrometallurgical technology, specifically relating to a method for enhanced gold extraction from cyanide tailings based on magnetically controlled hydrothermal magnetization activation and manganese doping treatment. The method includes: providing cyanide tailings particles; adding the cyanide tailings particles and a biomass reducing donor to an aqueous medium to form a slurry; adjusting the pH of the slurry to obtain an alkaline reaction system; adding a magnetothermal medium of ferric oxide or ferric chloride to the slurry and stirring with MnSO4 to obtain a reaction slurry; placing the reaction slurry in a closed magnetically controlled hydrothermal reactor and conducting a hydrothermal reaction under an external magnetic field; after cooling the reaction product, performing solid-liquid separation; performing graded magnetic separation on the solid phase; leaching the non-magnetic product using a thiosulfate-ammonia system to allow gold to enter the leaching solution; adding a recyclable magnetic gold-capturing carrier to the leaching solution for adsorption and enrichment; recovering the carrier through magnetic separation and regenerating it through analysis to obtain a gold-rich solution; and recovering gold from the gold-rich solution. The above method can stably achieve a synergistic gain in gold extraction and harm reduction under low-temperature hydrometallurgical conditions.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology, specifically relating to a method for enhanced gold extraction from cyanide tailings based on magnetically controlled hydrothermal magnetization activation and manganese doping treatment. Background Technology

[0002] Cyanide gold extraction has long dominated the gold beneficiation and smelting field due to its wide applicability and mature technology. However, its by-product, cyanide tailings, typically share common characteristics such as "difficult recovery of residual gold, cyanide content requiring harm reduction, and complex mineral phases making separation difficult." The residual gold in the tailings originates from both fine-grained gold and encapsulated gold that were not fully dissolved during cyanide leaching, as well as "difficult-to-extract gold" formed by re-adsorption, redeposition, or encapsulation by secondary minerals in the leaching and carbon adsorption system. In tailings containing significant amounts of iron or iron oxides, gold often exists as fine particles or thin films, encapsulated and locked within iron oxides and their hydrates. This makes it difficult for subsequent leaching agents to penetrate the inclusions, resulting in significantly limited mass transfer, low gold exposure, high reagent consumption, and difficulty in improving recovery rates. Furthermore, in addition to residual free cyanide, cyanide tailings may also contain complex components such as thiocyanates and polymetallic complexes, posing environmental risks and regulatory pressures if directly stockpiled. Existing harm reduction technologies include chemical oxidation, thermal decomposition, or roasting, but they often face problems such as long processes, high energy or chemical consumption, and heavy pressure on the treatment of secondary wastewater and exhaust gas. Furthermore, harm reduction and gold extraction are often separated into two separate processes, which limits the overall economic efficiency and engineering feasibility.

[0003] Common approaches to recovering residual gold include regrinding to enhance dissociation, roasting or pressurized oxidation to break down the encapsulation structure, alkaline leaching to desilicate and improve leaching accessibility, flotation enrichment of gold-bearing sulfide concentrate followed by further processing, and smelting for co-processing. However, in actual tailings systems, the close coexistence of gold and iron oxides, the mud-like encapsulation caused by excessively fine tailings particles, and the consumption of reagents and side reactions of iron relative to non-cyanide leaching systems make it difficult for a single enhancement method to simultaneously "increase gold exposure, reduce iron interference, avoid gold loss during separation, and achieve synergistic effects of harm reduction and gold extraction." It is particularly important to note that for tailings where "gold is encapsulated in ferric oxide," if only reduction is used to transform the iron phase from ferric oxide to magnetite, without simultaneously achieving porosification and cracking of the encapsulation structure or closed-loop recovery in the process flow, the apparent change may be "gold changing from being encapsulated in ferric oxide to being encapsulated in magnetite," which is difficult to translate into quantifiable gold extraction gains. Therefore, iron phase transformation must be coupled with structural activation and separation / diversion strategies: on the one hand, phase transformation-induced defects and microcracks are used to improve the accessibility of leaching agents; on the other hand, magnetic differences are used to achieve iron-containing phase diversion and enrichment and to perform closed-loop recovery of gold that migrates with the magnetic phase, while reducing iron interference in non-magnetic branches, thereby ensuring an improvement in the overall recovery rate at both the mechanism and process ends.

[0004] Chinese patent application CN107460336A studied the treatment of gold cyanide slag, proposing to mix the cyanide slag with reducing agents and additives, followed by reduction roasting to destroy the structure, and then enriching gold and silver precious metals through sorting. This method features structural destruction and precious metal enrichment through high-temperature treatment. However, it mainly relies on the thermodynamic drive and high-temperature reaction provided by roasting, resulting in high energy consumption and flue gas treatment pressure. Furthermore, it lacks sufficient support for the "directional dissociation and diversion closed-loop recovery" mechanism for finely encapsulated gold. Chinese patent CN106498177B provides a scheme for recovering and simultaneously rendering harmless gold, silver, and iron from cyanide tailings under roasting conditions. This method features harm reduction and multi-metal recovery through heat treatment, but the focus remains on high-temperature roasting and subsequent sorting, making it difficult to achieve source reduction of iron phase interference and rapid enrichment and recovery of gold in the solution phase within a low-temperature wet process system. Chinese patent application CN104550205A discloses a scheme for removing cyanide from cyanide tailings using autoclaving and hydrolysis, followed by flotation of secondary resource tailings to obtain sulfur concentrate. This scheme features enhanced cyanide removal through autoclaving and hydrolysis, and enrichment of sulfur-containing components through flotation. However, this approach is often sensitive to the floatability of sulfides in the tailings and the slurry system. For tailings where gold is encapsulated by iron oxides, it still faces issues of insufficient dissociation and unstable enrichment pathways. Chinese patent CN105349797B proposes a scheme for gold-bearing tailings or cyanide tailings involving first high-pressure, low-concentration alkaline leaching for desilication, followed by atmospheric-pressure, high-concentration alkaline leaching for further desilication, and then cyanidation for gold leaching. This scheme improves leaching accessibility through desilication. However, its process involves multiple alkaline leaching stages and ultimately returns to the cyanidation gold extraction system, presenting engineering constraints regarding equipment corrosion resistance, reagent circulation, and cyanide risk control. Furthermore, it lacks a systematic solution for iron phase interference and "magnetic flow separation closed-loop" mechanisms.

[0005] In summary, existing technologies still lack a method that can stably achieve a synergistic gain in gold extraction and harm reduction under low-temperature wet processing conditions. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a method for enhanced gold extraction from cyanide tailings based on magnetically controlled hydrothermal magnetization activation and manganese doping treatment that can stably achieve synergistic gains in gold extraction and harm reduction under low-temperature wet processing conditions.

[0007] To solve the above-mentioned technical problems, the technical solution is as follows: a method for enhanced gold extraction from cyanide tailings based on magnetically controlled hydrothermal magnetization activation and manganese doping treatment, comprising:

[0008] S1, provides cyanide tailings particles; S2. Cyanide tailings particles and biomass reduction donors are added to an aqueous medium to form a slurry. An alkaline regulator is added to adjust the pH of the slurry to obtain an alkaline reaction system. Ferric oxide magnetothermal medium or ferric chloride is added to the slurry, and MnSO4 is added and stirred to obtain a reaction slurry. S3. The reaction slurry is placed in a closed magnetically controlled hydrothermal reactor. Under the condition of an external magnetic field, the temperature is raised and kept at a constant temperature to carry out the hydrothermal reaction, so that the ferric oxide and hydrated iron oxide in the tailings are reduced and transformed to generate magnetic iron oxide. During the phase transformation reconstruction process, defects and microcracks are induced to form. S4. After the reaction product of S3 is cooled, solid-liquid separation is performed. The solid phase is subjected to graded magnetic separation to obtain magnetic iron-containing and non-magnetic products. S5. The non-magnetic product is leached using a thiosulfate-ammonia system to allow gold to enter the leaching solution; a recyclable magnetic gold-capturing carrier is added to the leaching solution for adsorption and enrichment; the carrier is recovered by magnetic separation and then regenerated by analysis to obtain a gold-rich solution; and gold is recovered from the gold-rich solution.

[0009] In one embodiment, the gold content of the cyanide tailings is 0.1–20 g / t, the iron content is 1%–60% by mass, the particle size D50 of the cyanide tailings particles is 5–150 μm, and the D90 is less than 300 μm.

[0010] In one embodiment, the biomass reduction donor is at least one of waste molasses, sugar residue extract, starch saccharification liquid, cellulose hydrolysate, lignin alkali solution, and fruit pomace extract, and the mass ratio of the biomass reduction donor to dry-based cyanidation tailings is 0.02 to 0.35:1.

[0011] In one embodiment, the alkaline regulator is at least one of NaOH, KOH, Ca(OH)2 and Na2CO3, the pH of the slurry is 9 to 13, and the solid-liquid ratio is 1:0.8 to 1:10.

[0012] In one embodiment, the hydrothermal reaction temperature is 130–230 °C, and the holding time is 0.5–8 h.

[0013] In one embodiment, the applied magnetic field is an alternating magnetic field and a static magnetic field. The frequency of the alternating magnetic field is 0.1 to 500 kHz and the magnetic field strength is 2 to 30 kA / m. The magnetic induction intensity of the static magnetic field is 0.05 to 1.2 T.

[0014] In one embodiment, the graded magnetic separation adopts a combination of low field strength pre-magnetic separation and medium field strength fine separation, with the low field strength being 0.05 to 0.30 T and the medium field strength being 0.30 to 1.2 T.

[0015] In one embodiment, in the thiosulfate-ammonia system, the concentration of thiosulfate is 0.05–1.0 mol / L, the pH is 8–11, the liquid-solid ratio is 1:1–10:1, the leaching temperature is 20–80°C, and the leaching time is 0.5–24 h.

[0016] In one embodiment, the magnetic gold-catching carrier is a magnetic biochar composite material, comprising a biochar framework and a magnetic iron phase or an iron-manganese composite magnetic phase, and the surface of the magnetic gold-catching carrier has sulfur-containing and nitrogen-containing coordination sites; the dosage of the magnetic gold-catching carrier is 0.2–20 g / L, and the adsorption time is 5–180 min.

[0017] In one embodiment, an acidic thiourea desorption system is used for desorption and regeneration, with a thiourea concentration of 0.05–1.0 mol / L, a pH of 0.5–2.5, a desorption and regeneration temperature of 20–80 °C, and a desorption and regeneration time of 5–180 min.

[0018] Beneficial Effects: This invention achieves integrated enhancement of phase change structure activation, interference source reduction, and rapid enrichment and recovery of the solution phase through a synergistic process path involving cyanide tailings particles and biomass reduction to form a slurry, magnetically controlled hydrothermal reduction, solid-liquid separation and graded magnetic separation, non-cyanide leaching, and enrichment, magnetic separation, and analytical regeneration of the magnetic gold-collecting carrier. In the magnetically controlled hydrothermal stage, under low-temperature wet processing conditions, ferric oxide and hydrated iron oxides are directionally converted into magnetic magnetite. During the phase change reconstruction process, defects, microcracks, and porous structures are induced, loosening the originally dense and locked iron phase shell and increasing permeability. This improves gold exposure and leaching agent accessibility, avoiding situations where only the encapsulated phase is replaced without significant gold extraction gains. Mechanistically, this improves subsequent leaching efficiency and recovery ceiling.

[0019] This invention utilizes staged magnetic separation to perform windowed stripping of magnetic iron-containing phases, enabling source separation of the iron-containing interfering phase before it enters the leaching unit. After the iron-containing phase is magnetized and enriched, the iron load on the non-magnetic products decreases, thereby reducing the ineffective consumption and side reaction induction of iron in the thiosulfate-ammonia system. This reduces reagent consumption and system fluctuations during leaching, improving leaching kinetics and process stability. Compared to methods that rely solely on extending leaching time or increasing reagent concentration to combat iron interference, this invention achieves pre-control of the interference source through a process design of stripping before leaching, which is beneficial for achieving higher recovery consistency and lower operating costs.

[0020] This invention introduces a recyclable magnetic gold-capturing carrier to achieve rapid adsorption and enrichment of gold in leachate, as well as efficient solid-liquid separation. Gold is directionally captured at the carrier's pores and surface sulfur- and nitrogen-containing coordination active sites. The carrier is then rapidly recovered via magnetic separation and regenerated through desorption to obtain a gold-rich solution, forming a closed loop of adsorption enrichment, solid-liquid separation, and desorption recovery. Compared to traditional filtration sedimentation or methods relying solely on conventional activated carbon adsorption, this invention significantly shortens solid-liquid separation time, reduces the risk of carrier loss, increases enrichment rate and recovery efficiency, and allows for carrier recycling, reducing adsorbent consumption and secondary solid waste generation.

[0021] This invention primarily utilizes a wet process, taking waste biomass as a low-cost source for reduction and activation. Key processes consist of magneto-controlled hydrothermal reaction, graded magnetic separation, non-cyanide leaching, and magnetic separation recovery. The equipment is highly versatile and easily modularized for integration. Compared to energy-intensive routes such as high-temperature roasting or pressurized oxidation, this invention reduces energy consumption and pollution control pressure while achieving synergistic gains in residual gold recovery and cyanide reduction. Furthermore, it enhances recovery stability and scale-up adaptability through a combined mechanism of structural activation, interference stripping, and magnetic gold capture, demonstrating promising prospects for engineering and industrial applications. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a magnetically controlled hydrothermal reaction device according to an embodiment of the present invention. Wherein, 1: feed port and valve; 2: corrosion-resistant lining; 3: temperature sensor; 4: stirring paddle; 5: alternating magnetic field coil module; 6: pressure-resistant shell layer; 7: material; 8: outer shell of the reaction device; 9: thermal insulation layer; 10: discharge port. Detailed Implementation

[0024] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0025] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0026] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0027] Please see Figure 1 One embodiment of the gold extraction method for enhanced cyanide tailings based on magnetized hydrothermal magnetization activation and manganese doping treatment includes the following steps: S1, provides cyanide tailings particles; The gold content in the cyanide tailings is 0.1–20 g / t, and the iron content is 1%–60% by mass. The particle size D50 of the cyanide tailings particles is 5–150 μm, and the D90 is less than 300 μm.

[0028] S2. Cyanide tailings particles and biomass reduction donors are added to an aqueous medium to form a slurry, and an alkaline regulator is added to adjust the pH of the slurry to obtain an alkaline reaction system. The biomass reduction donor has the ability to stably release reducing intermediates and surface-activating components under hydrothermal conditions.

[0029] Specifically, the biomass reduction donor is at least one of waste molasses, sugar residue extract, starch saccharification liquid, cellulose hydrolysate, lignin alkali solution, and fruit pomace extract. The mass ratio of the biomass reduction donor to dry-based cyanidation tailings is 0.02 to 0.35:1, in order to provide a controllable reduction equivalent and enhance the directional conversion of the iron phase.

[0030] The alkaline regulator is at least one of NaOH, KOH, Ca(OH)2 and Na2CO3, the pH of the slurry is 9 to 13, and the solid-liquid ratio is 1:0.8 to 1:10.

[0031] S3. Place the reaction slurry in a sealed magnetically controlled hydrothermal reactor (e.g., Figure 1 (As shown) Under the condition of an external magnetic field, the temperature is raised and kept at a high temperature to carry out a hydrothermal reaction, which causes the ferric oxide and hydrated iron oxide in the tailings to undergo reduction and transformation to generate magnetic iron tetroxide. During the phase transformation and reconstruction process, defects and microcracks are induced to form, thereby weakening the dense encapsulation and locking structure and improving the gold exposure and leaching agent accessibility, while reducing the load of residual cyanide and complexed cyanide.

[0032] Specifically, the hydrothermal reaction temperature is 130–230 °C, and the holding time is 0.5–8 h.

[0033] The applied magnetic field consists of an alternating magnetic field and a static magnetic field. The frequency of the alternating magnetic field is 0.1–500 kHz and the magnetic field strength is 2–30 kA / m. The magnetic induction intensity of the static magnetic field is 0.05–1.2 T, in order to enhance heat and mass transfer and improve magnetic cohesion and separability.

[0034] S4. After the reaction product from S3 cools, solid-liquid separation is performed. The solid phase is subjected to graded magnetic separation to obtain magnetic iron-containing and non-magnetic products. This achieves source stripping and enrichment of the iron-containing interfering phase, yielding a low-iron-interference raw material for subsequent gold extraction. The graded magnetic separation uses a combination of low-field pre-magnetic separation and medium-field fine separation. The low field strength is 0.05–0.30 T, and the medium field strength is 0.30–1.2 T, to achieve efficient stripping of iron-containing phases and obtain non-magnetic products with low iron interference.

[0035] S5. Non-magnetic products are leached using a thiosulfate-ammonia system to allow gold to enter the leaching solution. A recyclable magnetic gold-capturing carrier is added to the leaching solution for adsorption and enrichment. The carrier is recovered by magnetic separation and then regenerated through analysis to obtain a gold-rich solution. Gold is recovered from the gold-rich solution. Specifically, the gold-rich solution recovers the gold product through displacement, electrodeposition, or reduction precipitation. The analyzed carrier is washed and recycled.

[0036] In the thiosulfate-ammonia system, the concentration of thiosulfate is 0.05–1.0 mol / L, the pH is 8–11, the liquid-solid ratio is 1:1–10:1, the leaching temperature is 20–80℃, and the leaching time is 0.5–24 h, in order to improve leaching kinetics and reduce environmental risks.

[0037] The magnetic gold-catching carrier is a magnetic biochar composite material, comprising a biochar framework and a magnetic iron phase or an iron-manganese composite magnetic phase. The surface of the magnetic gold-catching carrier has sulfur-containing and nitrogen-containing coordination sites. The dosage of the magnetic gold-catching carrier is 0.2–20 g / L, and the adsorption time is 5–180 min, so that gold is enriched in the carrier pores and surface active sites and rapid solid-liquid separation is achieved through magnetic separation.

[0038] An acidic thiourea desorption system was used for desorption and regeneration. The thiourea concentration was 0.05–1.0 mol / L, the pH was 0.5–2.5, the desorption and regeneration temperature was 20–80 ℃, and the desorption and regeneration time was 5–180 min. The carrier was recycled at least 5 times and the adsorption capacity retention rate was not less than 80%.

[0039] Example 1 A method for enhanced gold extraction from cyanide tailings based on magnetized hydrothermal magnetization activation and manganese doping treatment includes the following steps: Take 1000 g of cyanide tailings, with a tailings D50 of approximately 45 μm, a gold content of approximately 2.5 g / t, a total cyanide content of approximately 380 mg / kg, and an iron content of approximately 20% by mass. Take 120 g of waste molasses by-products (based on solids), add deionized water to prepare a biomass reduction donor solution, and stir until homogeneous. Add the tailings and biomass reduction donor solution to a stirred tank, add deionized water to adjust the solid-liquid ratio to 1:3, add NaOH to adjust the pH of the slurry to 11.2, and stir for 20 min to obtain a homogeneous slurry. Add 20 g of magnetothermal medium (Fe3O4) and MnSO4 to the slurry, making the amount of Mn added 0.3% of the dry weight of the tailings, and continue stirring for 10 min.

[0040] The slurry was transferred to a closed magneto-controlled hydrothermal reactor and held at 190 °C for 2 h. Simultaneously, an alternating magnetic field with a frequency of 200 kHz and a magnetic field strength of 12 kA / m was applied, along with a static magnetic field with a magnetic induction intensity of 0.20 T. After the reaction, the mixture was cooled to room temperature. The reaction product was then subjected to solid-liquid separation to obtain the solid phase. The solid phase was subjected to staged magnetic separation. First, pre-magnetic separation at 0.15 T was used to obtain magnetic iron-containing particles. Then, the non-magnetic portion was further refined and weakly magnetic particles were recovered at 0.60 T, ultimately yielding both magnetic iron-containing and non-magnetic products.

[0041] Non-magnetic products were added to a leaching vessel and leached using a thiosulfate-ammonia system. The thiosulfate concentration was 0.40 mol / L, the total ammonia concentration was 0.80 mol / L, and CuSO4 was used as a catalyst to leach Cu. 2+ The concentration was 0.002 mol / L, pH was 9.8, liquid-to-solid ratio was 4:1, temperature was 35 ℃, and leaching was carried out with stirring for 8 h. After leaching, solid-liquid separation was performed to obtain the leachate. 5 g / L of magnetic gold-collecting carrier was added to the leachate, and the mixture was stirred and adsorbed for 60 min to enrich gold in the carrier channels and sulfur- and nitrogen-containing active sites on the surface. The carrier was then recovered by magnetic separation and regenerated by elution with an acidic thiourea solution (thiourea concentration 0.50 mol / L, pH 1.2, temperature 50 ℃, elution for 60 min) to obtain a gold-rich solution. Gold was recovered from the gold-rich solution by electrowinning, and the eluted carrier was washed and recycled.

[0042] The test results showed that the total gold recovery rate was 93.1%, the gold leaching rate in the leaching section was 90.7%, the gold capture and desorption recovery rate was 98.6%, and the total cyanide reduction rate after hydrothermal treatment was 98.9%.

[0043] Example 2 A method for enhanced gold extraction from cyanide tailings based on magnetized hydrothermal magnetization activation and manganese doping treatment includes the following steps: Take 1000 g of cyanide tailings, with a tailings D50 of approximately 45 μm, a gold content of approximately 2.5 g / t, a total cyanide content of approximately 380 mg / kg, and an iron content of approximately 20% by mass. Take 150 g of starch (based on solids) and add it to deionized water to prepare a reducing donor solution, stirring until homogeneous. Add the tailings and reducing donor solution to a stirred tank, add deionized water to adjust the solid-liquid ratio to 1:3, add NaOH to adjust the pH of the slurry to 10.8, and stir for 20 min to obtain a homogeneous slurry. Add 20 g of magnetothermal medium (Fe3O4) and MnSO4 to the slurry, making the amount of Mn added 0.3% of the dry weight of the tailings, and continue stirring for 10 min.

[0044] The slurry was transferred to a closed magnetron-controlled hydrothermal reactor and held at 180 °C for 3 h. An alternating magnetic field with a frequency of 200 kHz and a strength of 12 kA / m was applied simultaneously, along with a static magnetic field with a magnetic induction of 0.20 T. After the reaction, the mixture was cooled to room temperature. The reaction product was then subjected to solid-liquid separation to obtain the solid phase. The solid phase was subjected to staged magnetic separation. First, pre-magnetic separation at 0.15 T was used to obtain magnetic iron-containing particles. Then, the non-magnetic portion was further refined and weakly magnetic particles were recovered at 0.60 T, ultimately yielding both magnetic iron-containing and non-magnetic products.

[0045] Non-magnetic products were added to a leaching vessel and leached using a thiosulfate-ammonia system. The thiosulfate concentration was 0.35 mol / L, the total ammonia concentration was 0.70 mol / L, and CuSO4 was used as a catalyst to leach Cu. 2+ The concentration was 0.002 mol / L, pH was 9.8, liquid-to-solid ratio was 4:1, temperature was 35 ℃, and leaching was carried out with stirring for 8 h. After leaching, solid-liquid separation was performed to obtain the leachate. 6 g / L of magnetic gold-collecting carrier was added to the leachate, and the mixture was stirred and adsorbed for 60 min to enrich gold in the carrier channels and sulfur- and nitrogen-containing active sites on the surface. The carrier was then recovered by magnetic separation and regenerated by elution with an acidic thiourea solution (thiourea concentration 0.50 mol / L, pH 1.2, temperature 50 ℃, elution time 60 min) to obtain a gold-rich solution. Gold products were recovered from the gold-rich solution by electrowinning, and the eluted carrier was washed and recycled.

[0046] The test results showed that the total gold recovery rate was 91.8%, the gold leaching rate in the leaching section was 89.4%, the gold capture and analysis recovery rate was 98.1%, and the total cyanide reduction rate after hydrothermal treatment was 98.3%.

[0047] Example 3 A method for enhanced gold extraction from cyanide tailings based on magnetized hydrothermal magnetization activation and manganese doping treatment includes the following steps: Take 1000 g of cyanide tailings, with a tailings D50 of approximately 45 μm, a gold content of approximately 2.5 g / t, a total cyanide content of approximately 380 mg / kg, and an iron content of approximately 20% by mass. Take 120 g of waste molasses by-products (based on solids), add deionized water to prepare a reducing donor solution, and stir until homogeneous. Add the tailings and reducing donor solution to a stirred tank, add deionized water to adjust the solid-liquid ratio to 1:3, add NaOH to adjust the pH of the slurry to 11.0, and stir for 20 min to obtain a homogeneous slurry. Add 20 g of ferric chloride and MnSO4 to the slurry, making the amount of Mn added 0.3% of the dry weight of the tailings, and continue stirring for 10 min.

[0048] The slurry was transferred to a closed magneto-controlled hydrothermal reactor and held at 200 °C for 1.5 h. Simultaneously, an alternating magnetic field with a frequency of 250 kHz and a magnetic field strength of 12 kA / m was applied, along with a static magnetic field with a magnetic induction intensity of 0.25 T. After the reaction, the mixture was cooled to room temperature. The reaction product was then subjected to solid-liquid separation to obtain the solid phase. The solid phase was subjected to staged magnetic separation. First, pre-magnetic separation at 0.18 T was used to obtain magnetic iron-containing particles. Then, the non-magnetic portion was further refined and weakly magnetic particles were recovered at 0.65 T, ultimately yielding both magnetic iron-containing and non-magnetic products.

[0049] Non-magnetic products were added to a leaching vessel and leached using a thiosulfate-ammonia system. The thiosulfate concentration was 0.40 mol / L, the total ammonia concentration was 0.80 mol / L, and CuSO4 was used as a catalyst to leach Cu. 2+ The concentration was 0.002 mol / L, pH was 9.8, liquid-to-solid ratio was 4:1, temperature was 35 ℃, and leaching was carried out with stirring for 8 h. After leaching, solid-liquid separation was performed to obtain the leachate. 5 g / L of magnetic gold-collecting carrier was added to the leachate, and the mixture was stirred and adsorbed for 45 min to enrich gold in the carrier channels and sulfur- and nitrogen-containing active sites on the surface. The carrier was then recovered by magnetic separation and regenerated by analysis with an acidic thiourea solution (thiourea concentration 0.50 mol / L, pH 1.2, temperature 50 ℃, analysis for 60 min) to obtain a gold-rich solution. Gold products were recovered from the gold-rich solution by electrowinning, and the analyzed carrier was washed and recycled.

[0050] The test results showed that the total gold recovery rate was 92.6%, the gold leaching rate in the leaching section was 90.1%, the gold capture and analysis recovery rate was 96.8%, and the total cyanide reduction rate after hydrothermal treatment was 97.0%.

[0051] Comparative Example 1 Compared with Example 1, Comparative Example 1 did not add biomass reduction donors, but the remaining pulping conditions, magnetically controlled hydrothermal conditions, graded magnetic separation conditions, leaching conditions, gold capture and desorption conditions were the same as those in Example 1.

[0052] The test results showed that the total gold recovery rate was 76.4%, the gold leaching rate in the leaching stage was 74.2%, the gold capture and desorption recovery rate was 87.9%, and the total cyanide reduction rate after hydrothermal treatment was 82.1%. These results indicate that without the reducing equivalent from biomass supply and interfacial activation, the directional transformation of the iron phase and the activation of the phase change structure are insufficient, resulting in limited loosening of the encapsulated structure and limiting subsequent leaching enhancement.

[0053] Comparative Example 2 Compared with Example 1, in Comparative Example 2, the solid phase obtained by removing the iron-containing interfering phase without graded magnetic separation was directly leached into the thiosulfate-ammonia system, and the other conditions were the same as in Example 1.

[0054] The test results showed that the total gold recovery rate was 84.2%, the gold leaching rate in the leaching section was 81.0%, the gold capture and desorption recovery rate was 88.2%, and the total cyanide reduction rate after hydrothermal treatment was 88.5%. The concentration of dissolved iron in the leachate increased, as did the consumption of thiosulfate and ammonia. These results indicate that without source stripping of the iron-containing interfering phase, the ineffective consumption and side reactions induced by the iron phase are enhanced, leading to a decrease in leaching kinetics and recovery stability.

[0055] Table 1. Comparison of gold recovery and effects between the examples and comparative examples.

[0056] Table 1 shows that the total gold recovery rates of Examples 1 to 3 were significantly higher than those of Comparative Examples 1 and 2, with Example 1 reaching 93.1%, an increase of 16.7% compared to Comparative Example 1 and 8.9% compared to Comparative Example 2. This indicates that the integrated pathway of the present invention, consisting of magnetically controlled hydrothermal magnetization activation, graded magnetic separation stripping, and magnetic gold capture and enrichment recovery, can produce a clear and stable gold recovery gain. In Comparative Example 1, without the addition of waste biomass reduction donors, the total gold recovery rate, gold leaching rate in the leaching stage, and total cyanide reduction rate after hydrothermal treatment decreased to 76.4%, 74.2%, and 82.1%, respectively. This reflects that the reduction equivalent and interfacial activation effect provided by biomass have a decisive contribution to the directional transformation of the iron phase and the activation of the phase change structure. The absence of this step will lead to insufficient loosening of the encapsulation structure, limited improvement in gold exposure, and a simultaneous decrease in the harm reduction effect. In Comparative Example 2, after the elimination of staged magnetic separation, the total gold recovery rate and the leaching rate of the leaching stage decreased to 84.2% and 81.0%, respectively, accompanied by an increase in dissolved iron in the leachate and increased consumption of thiosulfate and ammonia. This indicates that staged magnetic separation can reduce iron-containing interfering phases before leaching, reduce ineffective consumption and side reactions, and improve the kinetics and stability of the thiosulfate-ammonia system, thereby enhancing the overall recovery performance. Among the examples, Example 1 showed the most balanced performance in terms of total gold recovery rate and total cyanide reduction rate; Example 2 had a slightly lower total gold recovery rate due to changes in donor type and hydrothermal window, but still maintained a high level; Example 3, while maintaining a high total gold recovery rate, saw a slight decrease in gold capture and desorption recovery rates and total cyanide reduction rate, suggesting that changes in the medium composition may affect the impurity background of the leachate and the adsorption and desorption process. Overall, the data validated that the present invention improves the leaching response through structural activation and pre-interference reduction, and achieves efficient enrichment and recovery of gold in the solution phase through magnetic gold capture, thereby achieving a synergistic gain in gold extraction and harm reduction under low-temperature wet processing conditions.

[0057] The above are merely preferred embodiments of the present invention. It should be noted that the present invention is not limited to the above embodiments. For those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for enhanced gold extraction from cyanide tailings based on magnetized hydrothermal magnetization activation and manganese doping treatment, characterized in that, Includes the following steps: S1, provides cyanide tailings particles; S2. Cyanide tailings particles and biomass reduction donors are added to an aqueous medium to form a slurry. An alkaline regulator is added to adjust the pH of the slurry to obtain an alkaline reaction system. Ferric oxide magnetothermal medium or ferric chloride is added to the slurry, and MnSO4 is added and stirred to obtain a reaction slurry. S3. The reaction slurry is placed in a closed magnetically controlled hydrothermal reactor. Under the condition of an external magnetic field, the temperature is raised and kept at a constant temperature to carry out the hydrothermal reaction, so that the ferric oxide and hydrated iron oxide in the tailings are reduced and transformed to generate magnetic iron oxide. During the phase transformation reconstruction process, defects and microcracks are induced to form. S4. After the reaction product of S3 is cooled, solid-liquid separation is performed. The solid phase is subjected to graded magnetic separation to obtain magnetic iron-containing and non-magnetic products. S5. The non-magnetic product is leached using a thiosulfate-ammonia system to allow gold to enter the leaching solution; a recyclable magnetic gold-capturing carrier is added to the leaching solution for adsorption and enrichment; the carrier is recovered by magnetic separation and then regenerated by analysis to obtain a gold-rich solution; and gold is recovered from the gold-rich solution.

2. The method for enhanced gold extraction from cyanide tailings based on magnetically controlled hydrothermal magnetization activation and manganese doping treatment according to claim 1, characterized in that, The gold content of the cyanide tailings is 0.1–20 g / t, the iron content is 1%–60% by mass, the particle size D50 of the cyanide tailings particles is 5–150 μm, and the D90 is less than 300 μm.

3. The method for enhanced gold extraction from cyanide tailings based on magnetically controlled hydrothermal magnetization activation and manganese doping treatment according to claim 1, characterized in that, The biomass reduction donor is at least one of waste molasses, sugar residue extract, starch saccharification liquid, cellulose hydrolysate, lignin alkaline solution, and fruit pomace extract, and the mass ratio of the biomass reduction donor to dry-based cyanidation tailings is 0.02 to 0.35:

1.

4. The method for enhanced gold extraction from cyanide tailings based on magnetically controlled hydrothermal magnetization activation and manganese doping treatment according to claim 1, characterized in that, The alkaline regulator is at least one of NaOH, KOH, Ca(OH)2 and Na2CO3, the pH of the slurry is 9 to 13, and the solid-liquid ratio is 1:0.8 to 1:

10.

5. The method for enhanced gold extraction from cyanide tailings based on magnetically controlled hydrothermal magnetization activation and manganese doping treatment according to claim 1, characterized in that, The hydrothermal reaction temperature is 130–230 °C, and the holding time is 0.5–8 h.

6. The method for enhanced gold extraction from cyanide tailings based on magnetically controlled hydrothermal magnetization activation and manganese doping treatment according to claim 1, characterized in that, The applied magnetic field is an alternating magnetic field and a static magnetic field. The frequency of the alternating magnetic field is 0.1 to 500 kHz and the magnetic field strength is 2 to 30 kA / m. The magnetic induction intensity of the static magnetic field is 0.05 to 1.2 T.

7. The method for enhanced gold extraction from cyanide tailings based on magnetically controlled hydrothermal magnetization activation and manganese doping treatment according to claim 1, characterized in that, The graded magnetic separation uses a combination of low-field-strength pre-magnetic separation and medium-field-strength fine separation, with the low field strength being 0.05–0.30 T and the medium field strength being 0.30–1.2 T.

8. The method for enhanced gold extraction from cyanide tailings based on magnetically controlled hydrothermal magnetization activation and manganese doping treatment according to claim 1, characterized in that, In the thiosulfate-ammonia system, the concentration of thiosulfate is 0.05–1.0 mol / L, the pH is 8–11, the liquid-solid ratio is 1:1–10:1, the leaching temperature is 20–80℃, and the leaching time is 0.5–24 h.

9. The method for enhanced gold extraction from cyanide tailings based on magnetically controlled hydrothermal magnetization activation and manganese doping treatment according to claim 1, characterized in that, The magnetic gold-catching carrier is a magnetic biochar composite material, comprising a biochar framework and a magnetic iron phase or an iron-manganese composite magnetic phase. The surface of the magnetic gold-catching carrier has sulfur-containing and nitrogen-containing coordination sites. The dosage of the magnetic gold-catching carrier is 0.2–20 g / L, and the adsorption time is 5–180 min.

10. The method for enhanced gold extraction from cyanide tailings based on magnetically controlled hydrothermal magnetization activation and manganese doping treatment according to claim 1, characterized in that, An acidic thiourea resorption system was used for resorption and regeneration. The thiourea concentration was 0.05–1.0 mol / L, the pH was 0.5–2.5, the resorption and regeneration temperature was 20–80 ℃, and the resorption and regeneration time was 5–180 min.

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