Method for efficiently recovering valuable components from low-iron-sulfur flotation tailings containing gold and silver

Abstract

The invention relates to a method for efficiently recovering valuable components from low-iron-sulfur flotation tailings containing gold and silver, which comprises the following steps of: selectively sorting a material to be treated to obtain light overflow and heavy sand with the particle size of-0.037 mm accounting for 70-80%; recovering gold, silver and sulfur in the light overflow to obtain concentrate I containing gold, silver and sulfur and tailings I; grinding and grading the heavy sand to obtain graded overflow with the particle size of 0.043 mm accounting for 80%-85% and the concentration of 30%-35%; carrying out bulk flotation on the graded overflow and the gold-silver-containing sulfur concentrate I to obtain gold-silver-containing sulfur concentrate II and tailings II; carrying out mixed magnetic separation on the tailings II strong / weak magnetite to obtain gold-silver-iron-containing concentrate and tailings III; mixing and roasting the gold-silver-containing sulfur concentrate II and the gold-silver-containing iron concentrate in a reasonable proportion to obtain gold-silver-containing roasting slag and sulfuric acid; the roasting slag is subjected to water washing and carbon leaching, and activated carbon carrying gold and silver and high-quality iron ore concentrate are obtained; the gold and silver loaded activated carbon is subjected to traditional desorption, electrodeposition, smelting, gold and silver separation and ingot casting, and a gold ingot and a silver ingot are obtained. According to the method, comprehensive, efficient, green and tailing-free utilization of the low-iron-sulfur gold and silver-containing tailings is achieved through the steps.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metallurgy and low-grade flotation tailings recovery, and particularly relates to a method for efficiently recovering valuable components from low-iron-sulfur gold-silver-containing flotation tailings. BACKGROUND

[0002] Gold mineral resources have the attribute of non-renewability. With the exhaustion of easy-to-mine resources, secondary utilization of tailings has become the only way for sustainable development of the mining industry. Gold tailings in China generally contain Au 0.4-0.8 g / t, Ag 6-10 g / t, Fe 15-20%, and S 1-3%. Gold is mostly in the form of intergrowth or inclusions, iron coexists in the form of magnetite, limonite and siderite, and sulfur is contained in sulfide ore and sulfate. Gold tailings have the characteristics of "poor, fine and complex". The existing gold recovery methods mainly include gravity separation, flotation, amalgamation, cyanidation and other leaching methods. Gravity separation is mainly used for recovering coarse-grained gold, and the obtained gold concentrate has low grade and recovery rate. Flotation can only recover single fine-grained gold or gold along with intergrowth carrier minerals. Amalgamation pollutes the environment and has been eliminated. Cyanidation and other leaching methods have high extraction cost and are difficult to recover gold with inclusions or many interference factors. Due to the defects of the above-mentioned recovery methods and the complexity of the existing scene, any single recovery method has certain limitations. Therefore, how to recover valuable components from gold-containing flotation tailings and maximize the extraction of valuable metals is still a difficult problem in the field of gold production.

[0003] In this regard, researchers in the field have carried out a lot of research, and there are reports on the recovery of gold from flotation tailings. For example, S1: Hu Shanyou et al. Flotation process test research and practice of a gold tailings [J]. Gold, 2004, 25(12): 42-44, which records the use of sodium carbonate as a pH adjuster, copper sulfate as an activator, and the use of single flotation to recover gold, with a gold recovery rate of 69%. S2: Wang Gai-chao et al. Production practice of recovering gold from flotation tailings [J]. Gold, 2004, 25(9): 41-42, which records that a portion of gold is recovered by using a chute-shaking table for pre-concentration and then using grinding-mercury mixing for further treatment, which seriously pollutes the environment. S3: CN104841565A A method for recovering gold from gold flotation tailings, which is to grind the gold flotation tailings, add lime to adjust the pH value, then add emulsifier, flocculant, collector and foaming agent to adjust the slurry, and then float to obtain a gold concentrate with a gold recovery rate of 70%. However, this process grinds all tailings, and the types and consumption of reagents are high, resulting in high production cost. In addition, the technical solutions recorded in the above documents recover only one element, and there is a lack of economic and environmental benefits in the recovery of gold and silver from tailings with dispersed and complex inclusions and many interference factors.

[0004] In order to overcome the deficiencies or defects of the prior art, the present application provides a green process for efficiently recovering valuable components such as gold, silver, iron and sulfur from low-iron-sulfur gold-silver flotation tailings and synchronously preparing building materials. SUMMARY

[0005] The present application provides a method for efficiently recovering valuable components from low-iron-sulfur gold-silver flotation tailings, which is based on material characteristics and innovatively adopts a technical route of "classification gradient recovery and cross cooperation" to comprehensively and efficiently recover valuable components such as gold, silver, sulfur and iron in low-iron-sulfur gold-silver flotation tailings, and finally obtain gold ingots, silver ingots, sulfuric acid, high-quality iron concentrate and tailings that can be directly used as building materials.

[0006] The specific technical solution is: a method for efficiently recovering valuable components from low-iron-sulfur gold-silver flotation tailings, comprising the following steps: (1) Selective separation of the material to be treated: after the material to be treated is thickened, it is transported to a cyclone separator for separation to obtain light overflow and heavy sand with-0.037mm accounting for 70%-80%; This step can effectively control the separation ratio of light overflow and heavy sand, reduce the entrainment of the two, and ensure that the fine particle gold-silver-sulfur-iron ore that has been dissociated is preferentially separated into light overflow, while coarse particle intergrowths, quartz and oxidized iron are separated into heavy sand, thereby avoiding overgrinding and mudification.

[0007] (2) Acid activation and flotation of light overflow, specifically as follows: A1: Concentrate the light overflow obtained in step (1) to 60%-65% thickened slurry; A2: Add sulfuric acid to the thickened slurry of step A1 to adjust the pH to 2-3, stir for 5-10 minutes, then add dilution water to adjust the slurry concentration to 25%-30% and the pH to 6-6.5; A3: Transfer the slurry of step A2 to a flotation system for two roughing and two cleaning to obtain gold-silver-sulfur concentrate I and tailings I; This step adopts a combined process of "acidification first, then dilution, and then flotation", which first dissolves the iron hydroxide on the surface of the gold-silver-sulfur-iron ore (the surface of the sulfur-iron ore is oxidized during long-term stacking of the tailings) by high-concentration sulfuric acid to re-activate the gold-silver-sulfur-iron ore, and the specific reaction process is: Fe(OH)3 colloid dissolves at pH=2-3: Fe(OH)3+3H + →Fe 3+ +3H2O, exposing the fresh surface of the sulfur-iron ore; then dilution water is added to adjust the pH to 6-6.5 to avoid excessive Fe 3+Re-hydrolysis desorption under low pH flotation; finally, low concentration flotation with low bubble load and strong secondary enrichment, gold and sulfur float together with high flotation rate. It should be noted that the acidification time cannot be too long, otherwise Fe 3+ will erode pyrite, and S 0 oxidation on the surface will inhibit flotation.

[0008] (3) Heavy sand grinding and classification: the heavy sand of step (1) is ground and classified to obtain a classification overflow with-0.043 mm accounting for 80% to 85% and a concentration of 30% to 35%; The grinding of such intergrowth to-0.043 mm can make the dissociation degree of gold / silver and sulfide iron and oxidized iron ≥90%, providing "qualified particle size and stable concentration" for mixed flotation.

[0009] (4) Carrier mixed flotation: the classification overflow of step (3) and the gold-silver-sulfur concentrate I of step A3 are transferred into the flotation system for two roughing and two cleaning to obtain a gold-silver-sulfur concentrate II and a tailing II; This step mixes the classification overflow with the gold-silver-sulfur concentrate I for flotation, which can utilize the heterogeneous agglomeration-collision-adhesion between coarse-grained pyrite and fine-grained gold to realize the flotation of fine particles with the help of coarse-grained sulfur, thereby improving the recovery rate. At the same time, water glass can disperse silicate slime, reduce impurity flocculation, ensure the cleanliness of foam, improve product quality, and reduce the dosage of flotation reagents.

[0010] (5) Strong / weak magnetite mixed magnetic separation: a pulse high-gradient magnetic separator is used for one roughing and one cleaning of the tailing II of step (4) to obtain a gold-silver-iron concentrate (including magnetite, limonite and siderite) and a tailing III; the tailing III is combined with the tailing I of step (2) as a total tailing, which can be directly used as building materials; This step performs mixed strong magnetic separation on the gold-silver-magnetite and limonite, which can effectively utilize the magnetic agglomeration of magnetite itself, fully recover fine-grained limonite, avoid iron loss, and further recover the co-associated gold and silver. In addition, by increasing the diameter of the magnetic medium and the working gap (2-4 mm), the magnetic agglomeration can be prevented from blocking the magnetic separator, ensuring the efficiency of the magnetic separation.

[0011] (6) Mixed roasting: the gold-silver-sulfur concentrate II of step (4) and the gold-silver-iron concentrate of step (5) are mass-matched according to the theoretical sulfur content of 28% to 35% for roasting (if the sulfur content is insufficient, sulfur or a gold-silver-sulfur concentrate can be additionally added), and then delivered to a fine-grained roasting fluidized bed-acid production system for treatment to obtain a gold-silver roasting slag and sulfuric acid; This step cleverly combines gold-silver-sulfur concentrate II with gold-silver-iron concentrate for roasting, which can make full use of the sulfur in the gold-silver-sulfur concentrate as "self-heating fuel" to convert limonite and siderite in the iron concentrate into Fe2O3 / Fe3O4, thereby improving the iron grade; while the sulfur is oxidized into SO2 and directly used for acid production, realizing the resource utilization of sulfur; in addition, the roasting slag produces honeycomb pores, increasing the specific surface area for subsequent cyanide gold extraction.

[0012] (7) Roasting slag water washing-carbon leaching: The gold and silver-containing roasting slag from step (6) is washed and filtered to obtain rinsed slag (to remove soluble sulfates and acids and avoid unnecessary consumption of subsequent cyanide reagents) and acidic wastewater; then the rinsed slag is carbon leached to obtain gold and silver-loaded activated carbon and high-quality iron concentrate. (8) Gold and silver refining and casting: The gold and silver loaded activated carbon from step (7) is subjected to traditional desorption-electrowinning-smelting-gold and silver separation-casting to obtain gold and silver ingots.

[0013] Furthermore, in step (1), the feed concentration of the hydrocyclone separator is 40%~45%, the feed pressure is controlled at 0.035~0.15MPa, and the overflow of the separated light particles is controlled at 40%~60% of the total feed.

[0014] Furthermore, the dilution water in step A2 is preferably the overflow water obtained from the concentration in step A1, which saves water and contains a small amount of residual acid, thus stabilizing the pH.

[0015] Furthermore, in step A3, 40-80 g / t butyl xanthate and 20-30 g / t pine oil are added to the first coarse selection, and 20-40 g / t butyl xanthate and 10 g / t pine oil are added to the second coarse selection.

[0016] Furthermore, in step (3), a φ250 hydrocyclone is used for grading, and the grading concentration is 50%~55%.

[0017] Further, in step (4), 20~40g / t butyl xanthate and 10~20g / t pine oil are added to the first roughing process, 10~30g / t butyl xanthate and 10g / t pine oil are added to the second roughing process, and 300~500g / t water glass is added to the first fine selection process.

[0018] Furthermore, in step (5), the background magnetic field strength of the pulse high gradient magnetic separator is 750~900mT, the diameter of the magnetic medium and the working gap are 2~4mm, the pulse intensity is 100~200 times / minute, and the stroke is 15cm~20cm.

[0019] Furthermore, in step (6), the temperature of the fine-particle calcination fluidized bed furnace is controlled at 600~650℃.

[0020] Furthermore, in step (7), the total liquid-to-solid ratio of the water washing section is 3:1; in the carbon leaching section, lime is added to control the pH to 10.5~11.5, the sodium cyanide concentration is controlled to 0.5‰~0.7‰, and the leaching concentration is 35%~45%.

[0021] The beneficial effects of this invention are as follows: This invention achieves comprehensive and efficient recovery of gold, silver, iron, and sulfur from low-iron and sulfur-containing gold and silver flotation tailings and the reuse of tailings through a closed-loop process of graded separation, acid activation flotation, mixed magnetic separation, mixed roasting, and water washing and carbon leaching. The gold recovery rate is ≥80%, silver ≥75%, iron concentrate grade ≥60% and recovery rate ≥75%, sulfur recovery rate ≥85%, and sulfur content in tailings ≤0.15%. It has a high comprehensive utilization rate of resources and significant economic and environmental benefits. It solves the pain points of traditional processes such as single recovery components, low recovery rate, high reagent consumption, and inability to reuse tailings. It has demonstration and promotion value for the green transformation of the gold industry.

[0022] (1) Dual-effect separation can effectively separate fine-grained gold-silver-iron ore and coarse-grained intergrown oxide minerals in tailings. Combined with the corresponding "acid flotation" process, the ferric hydroxide colloid on the surface of the gold-silver-iron ore is dissolved, making it fully exposed and improving the flotation recovery rate. For the coarse-grained intergrown oxide minerals, further grinding and classification are carried out to further liberate them.

[0023] (2) The gold and silver sulfur concentrate obtained by acid flotation is mixed with the overflow of heavy sand classification and secondary flotation. This can make full use of the heterogeneous aggregation-collision-adhesion between coarse pyrite and fine gold, so that the fine particles can float with the help of coarse sulfur, thereby further improving the recovery rate. At the same time, water glass can disperse silicate mud, reduce flocculation, ensure foam cleanliness, improve product quality and reduce the amount of flotation reagents used.

[0024] (3) Using pulsed high gradient strong magnetic separation technology to mix and magnetically separate the tailings from the secondary flotation, fully capture the co-existing gold and silver in fine-grained limonite, siderite and iron oxide, and improve the recovery rate of iron and gold and silver.

[0025] (4) The intermediate products, gold and silver sulfur concentrate and gold and silver iron concentrate, are cleverly mixed and roasted in a reasonable ratio. The sulfur in the raw materials serves as a self-heating fuel, which can provide a heat source for roasting and can also be oxidized into SO2 in time for use by the acid production system. Moreover, this roasting process can convert limonite and siderite in the iron concentrate into Fe2O3 / Fe3O4, thereby improving the iron grade; and make the roasting slag form a honeycomb pore structure, which provides a larger specific surface area for subsequent cyanide gold extraction and promotes the improvement of cyanide extraction rate. Attached Figure Description

[0026] Figure 1 This is a flowchart of a method for efficiently recovering valuable components from low-iron, sulfur-containing gold and silver flotation tailings according to the present invention. Detailed Implementation

[0027] To make the technical problems and solutions solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. Example 1

[0028] Raw material #1: A low-iron, sulfur-containing gold and silver flotation tailings. The main valuable elements are Au, Ag, Fe, and S, with grades of 0.64 g / t, 7.8 g / t, 18.56%, and 1.98%, respectively. Gold in the tailings mainly exists in the form of intercalated and encapsulated gold, accounting for 89.68%. Iron mainly exists in the form of magnetite and limonite, accounting for 88.78%, followed by siderite. Gangue minerals are mainly quartz sand and silicates.

[0029] The method described in this invention is applied to raw material #1, and the specific steps are as follows: (1) Selective separation of materials to be processed: After the material to be processed is slurryed to a concentration of 40%~45%, it is fed to a hydrocyclone separator for separation to obtain light overflow and heavy sand with a content of -0.037mm accounting for 70%~80%. Among them, the feed pressure of the hydrocyclone separator is controlled at 0.035~0.15MPa, and the amount of light overflow separated is controlled at 40%~60% of the total feed. (2) Recovery of gold, silver and sulfur from light overflow, as detailed below: A1: The light overflow obtained in step (1) is sent to a thickener for concentration to obtain concentrated slurry and overflow water with a concentration of 60%~65%; A2: Add sulfuric acid to the concentrated slurry from step A1 to adjust the pH to 2-3. Stir for 5-10 minutes, then add dilution water to adjust the slurry concentration to 25%-30% and the pH to 6-6.5. A3: Transfer the slurry from step A2 into the flotation system for two roughing and two cleaning processes to obtain gold-silver-sulfur concentrate I and tailings I; wherein, 40g / t butyl xanthate and 25g / t pine oil are added to roughing process I, and 35g / t butyl xanthate and 10g / t pine oil are added to roughing process II.

[0030] (3) Heavy sand grinding and classification: The heavy sand from step (1) is ground and classified to obtain a classification overflow with -0.043mm content of 80%~85% and a concentration of 30%~35%; wherein, the classification is carried out by a φ250 hydrocyclone and the classification concentration is 50%~55%; (4) Carrier mixing flotation: The overflow from step (3) and the gold-silver-sulfur concentrate I from step A3 are transferred to the flotation system for two roughing and two cleaning processes to obtain gold-silver-sulfur concentrate II and tailings II; wherein, 30 g / t of butyl xanthate and 10 g / t of pine oil are added to roughing process I, 15 g / t of butyl xanthate and 10 g / t of pine oil are added to roughing process II, and 350 g / t of water glass is added to cleaning process I; (5) Strong / weak magnetite mixed magnetic separation: The tailings II from step (4) are roughed and cleaned once using a pulse high gradient magnetic separator to obtain gold-silver-iron concentrate (including magnetite, limonite and siderite) and tailings III; tailings III and tailings I from step (2) are combined into total tailings, which can be directly used as building materials; the operating parameters of the pulse high gradient magnetic separator are: background magnetic field strength 750~900mT, magnetic medium diameter and working gap 2~4mm, pulse intensity 100~120 times / minute, stroke 15~20cm; (6) Mixed roasting: The gold and silver sulfur concentrate II from step (4) and the gold and silver iron concentrate from step (5) are mixed according to the theoretical sulfur content of 28%~35% for roasting feed. After mixing, the mixture is sent to the fine-particle roasting fluidized bed furnace-acid production system for processing. The roasting temperature is controlled at 600~650℃. After roasting, gold and silver roasting residue and sulfuric acid are obtained. (7) Roasting slag water washing-carbon leaching: The gold and silver-containing roasting slag from step (6) is washed and filtered to obtain rinsed slag (to remove soluble sulfates and acids, and to avoid unnecessary consumption of subsequent cyanide reagents) and acidic wastewater; then the rinsed slag is carbon leached to obtain gold and silver-loaded activated carbon and high-quality iron concentrate; wherein, the total liquid-solid ratio in the water washing section is 3:1; in the carbon leaching section, the lime controls the pH to 10.5~11.5, the sodium cyanide concentration is controlled to 0.5‰~0.7‰, and the leaching concentration is 35%~45%.

[0031] (8) Gold and silver refining and casting: The gold and silver loaded activated carbon from step (7) is subjected to traditional desorption-electrowinning-smelting-gold and silver separation-casting to obtain gold and silver ingots.

[0032] The test results were as follows: gold recovery rate was 81.35%; silver recovery rate was 78.73%; iron grade of iron concentrate was 61.59% and iron recovery rate was 76.19%; sulfur recovery rate was 85.52%; and the tailings contained 0.14% sulfur, making it suitable as a high-quality building material. Example 2

[0033] Raw material #2: A low-iron, sulfur-containing gold and silver flotation tailings. The main valuable elements are Au, Ag, Fe, and S, with grades of 0.53 g / t, 8.55 g / t, 17.62%, and 2.15%, respectively. Gold in the tailings mainly exists in the form of intercalated and encapsulated gold, accounting for 88.58%. Iron mainly exists in the form of magnetite and limonite, accounting for 89.95%, followed by siderite. Gangue minerals are mainly quartz sand and silicates.

[0034] The method described in this invention is applied to raw material #2, and the specific steps are as follows: (1) Selective separation of materials to be processed: After the material to be processed is slurryed to a concentration of 40%~45%, it is fed to a hydrocyclone separator for separation to obtain light overflow and heavy sand with a content of -0.037mm accounting for 70%~80%. Among them, the feed pressure of the hydrocyclone separator is controlled at 0.035~0.15MPa, and the amount of light overflow separated is controlled at 40%~60% of the total feed. (2) Recovery of gold, silver and sulfur from light overflow, as detailed below: A1: The light overflow obtained in step (1) is sent to a thickener for concentration to obtain concentrated slurry and overflow water with a concentration of 60%~65%; A2: Add sulfuric acid to the concentrated slurry from step A1 to adjust the pH to 2-3. Stir for 5-10 minutes, then add dilution water to adjust the slurry concentration to 25%-30% and the pH to 6-6.5. A3: Transfer the slurry from step A2 into the flotation system for two roughing and two cleaning processes to obtain gold-silver-sulfur concentrate I and tailings I; wherein, 55g / t butyl xanthate and 20g / t pine oil are added to roughing process I, and 30g / t butyl xanthate and 10g / t pine oil are added to roughing process II.

[0035] (3) Heavy sand grinding and classification: The heavy sand from step (1) is ground and classified to obtain a classification overflow with -0.043mm content of 80%~85% and a concentration of 30%~35%; wherein, the classification is carried out by a φ250 hydrocyclone and the classification concentration is 50%~55%; (4) Carrier mixing flotation: The staged overflow from step (3) and the gold-silver-sulfur concentrate I from step A3 are transferred to the flotation system for two roughing and two cleaning processes to obtain gold-silver-sulfur concentrate II and tailings II; wherein, 40 g / t of butyl xanthate and 10 g / t of pine oil are added to roughing process I, 10 g / t of butyl xanthate and 10 g / t of pine oil are added to roughing process II, and 400 g / t of water glass is added to cleaning process I; (5) Strong / weak magnetite mixed magnetic separation: The tailings II from step (4) are roughed and cleaned once using a pulse high gradient magnetic separator to obtain gold-silver-iron concentrate (including magnetite, limonite and siderite) and tailings III; tailings III and tailings I from step (2) are combined into total tailings, which can be directly used as building materials; the operating parameters of the pulse high gradient magnetic separator are: background magnetic field strength 750~900mT, magnetic medium diameter and working gap 2~4mm, pulse intensity 130~170 times / minute, stroke 15~20cm; (6) Mixed roasting: The gold and silver sulfur concentrate II from step (4) and the gold and silver iron concentrate from step (5) are mixed according to the theoretical sulfur content of 28%~35% for roasting feed. After mixing, the mixture is sent to the fine-particle roasting fluidized bed furnace-acid production system for processing. The roasting temperature is controlled at 600~650℃. After roasting, gold and silver roasting residue and sulfuric acid are obtained. (7) Roasting slag water washing-carbon leaching: The gold and silver-containing roasting slag from step (6) is washed and filtered to obtain rinsed slag (to remove soluble sulfates and acids, and to avoid unnecessary consumption of subsequent cyanide reagents) and acidic wastewater; then the rinsed slag is carbon leached to obtain gold and silver-loaded activated carbon and high-quality iron concentrate; wherein, the total liquid-solid ratio in the water washing section is 3:1; in the carbon leaching section, the lime controls the pH to 10.5~11.5, the sodium cyanide concentration is controlled to 0.5‰~0.7‰, and the leaching concentration is 35%~45%.

[0036] (8) Gold and silver refining and casting: The gold and silver loaded activated carbon from step (7) is subjected to traditional desorption-electrowinning-smelting-gold and silver separation-casting to obtain gold and silver ingots.

[0037] The experimental results obtained are as follows: gold recovery rate is 80.07%; silver recovery rate is 79.62%; iron grade of iron concentrate is 61.17% and iron recovery rate is 77.84%; sulfur recovery rate is 86.13%; and the tailings contain 0.15% sulfur, which can be used as high-quality building material. Example 3

[0038] Raw material #3: A low-iron, sulfur-containing gold and silver flotation tailings. The main valuable elements are Au, Ag, Fe, and S, with grades of 0.72 g / t, 6.94 g / t, 17.85%, and 1.59%, respectively. Gold in the tailings mainly exists in the form of intercalated and encapsulated gold, accounting for 88.43%. Iron mainly exists in the form of magnetite and limonite, accounting for 88.15%, followed by siderite. Gangue minerals are mainly quartz sand and silicates.

[0039] The method described in this invention is applied to raw material #3, and the specific steps are as follows: (1) Selective separation of materials to be processed: After the material to be processed is slurryed to a concentration of 40%~45%, it is fed to a hydrocyclone separator for separation to obtain light overflow and heavy sand with a content of -0.037mm accounting for 70%~80%. Among them, the feed pressure of the hydrocyclone separator is controlled at 0.035~0.15MPa, and the amount of light overflow separated is controlled at 40%~60% of the total feed. (2) Recovery of gold, silver and sulfur from light overflow, as detailed below: A1: The light overflow obtained in step (1) is sent to a thickener for concentration to obtain concentrated slurry and overflow water with a concentration of 60%~65%; A2: Add sulfuric acid to the concentrated slurry from step A1 to adjust the pH to 2-3. Stir for 5-10 minutes, then add dilution water to adjust the slurry concentration to 25%-30% and the pH to 6-6.5. A3: Transfer the slurry from step A2 into the flotation system for two roughing and two cleaning processes to obtain gold-silver-sulfur concentrate I and tailings I; wherein, 80g / t butyl xanthate and 20g / t pine oil are added to roughing process I, and 20g / t butyl xanthate and 10g / t pine oil are added to roughing process II.

[0040] (3) Heavy sand grinding and classification: The heavy sand from step (1) is ground and classified to obtain a classification overflow with -0.043mm content of 80%~85% and a concentration of 30%~35%; wherein, the classification is carried out by a φ250 hydrocyclone and the classification concentration is 50%~55%; (4) Carrier mixing flotation: The overflow from step (3) and the gold-silver-sulfur concentrate I from step A3 are transferred to the flotation system for two roughing and two cleaning processes to obtain gold-silver-sulfur concentrate II and tailings II; wherein, butyl xanthate 25g / t and pine oil 15g / t are added in roughing process I, butyl xanthate 20g / t and pine oil 10g / t are added in roughing process II, and water glass 300g / t is added in cleaning process I; (5) Strong / weak magnetite mixed magnetic separation: The tailings II from step (4) are roughed and cleaned once using a pulse high gradient magnetic separator to obtain gold-silver-iron concentrate (including magnetite, limonite and siderite) and tailings III; tailings III and tailings I from step (2) are combined into total tailings, which can be directly used as building materials; the operating parameters of the pulse high gradient magnetic separator are: background magnetic field strength 750~900mT, magnetic medium diameter and working gap 2~4mm, pulse intensity 180~200 times / minute, stroke 15~20cm; (6) Mixed roasting: The gold and silver sulfur concentrate II from step (4) and the gold and silver iron concentrate from step (5) are mixed according to the theoretical sulfur content of 28%~35% for roasting feed. After mixing, the mixture is sent to the fine-particle roasting fluidized bed furnace-acid production system for processing. The roasting temperature is controlled at 600~650℃. After roasting, gold and silver roasting residue and sulfuric acid are obtained. (7) Roasting slag water washing-carbon leaching: The gold and silver-containing roasting slag from step (6) is washed and filtered to obtain rinsed slag (to remove soluble sulfates and acids, and to avoid unnecessary consumption of subsequent cyanide reagents) and acidic wastewater; then the rinsed slag is carbon leached to obtain gold and silver-loaded activated carbon and high-quality iron concentrate; wherein, the total liquid-solid ratio in the water washing section is 3:1; in the carbon leaching section, the lime controls the pH to 10.5~11.5, the sodium cyanide concentration is controlled to 0.5‰~0.7‰, and the leaching concentration is 35%~45%.

[0041] (8) Gold and silver refining and casting: The gold and silver loaded activated carbon from step (7) is subjected to traditional desorption-electrowinning-smelting-gold and silver separation-casting to obtain gold and silver ingots.

[0042] The test results obtained are as follows: gold recovery rate is 82.16%; silver recovery rate is 77.06%; iron grade of iron concentrate is 60.84% ​​and iron recovery rate is 78.51%; sulfur recovery rate is 87.47%; and the tailings contain 0.13% sulfur, which can be used as high-quality building material. Example 4

[0043] Raw material #4: A low-iron, sulfur-containing gold and silver flotation tailings. The main valuable elements are Au, Ag, Fe, and S, with grades of 0.49 g / t, 8.06 g / t, 16.47%, and 1.83%, respectively. Gold in the tailings mainly exists in the form of intercalated and encapsulated gold, accounting for 89.11%. Iron mainly exists in the form of magnetite and limonite, accounting for 89.55%, followed by siderite. Gangue minerals are mainly quartz sand and silicates.

[0044] The method described in this invention is applied to raw material #4, and the specific steps are as follows: (1) Selective separation of materials to be processed: After the material to be processed is slurryed to a concentration of 40%~45%, it is fed to a hydrocyclone separator for separation to obtain light overflow and heavy sand with a content of -0.037mm accounting for 70%~80%. Among them, the feed pressure of the hydrocyclone separator is controlled at 0.035~0.15MPa, and the amount of light overflow separated is controlled at 40%~60% of the total feed. (2) Recovery of gold, silver and sulfur from light overflow, as detailed below: A1: The light overflow obtained in step (1) is sent to a thickener for concentration to obtain concentrated slurry and overflow water with a concentration of 60%~65%; A2: Add sulfuric acid to the concentrated slurry from step A1 to adjust the pH to 2-3. Stir for 5-10 minutes, then add dilution water to adjust the slurry concentration to 25%-30% and the pH to 6-6.5. A3: Transfer the slurry from step A2 into a flotation system for two roughing and two cleaning processes to obtain gold-silver-sulfur concentrate I and tailings I; wherein, 65g / t butyl xanthate and 30g / t pine oil are added to roughing process I, and 40g / t butyl xanthate and 10g / t pine oil are added to roughing process II.

[0045] (3) Heavy sand grinding and classification: The heavy sand from step (1) is ground and classified to obtain a classification overflow with -0.043mm content of 80%~85% and a concentration of 30%~35%; wherein, the classification is carried out by a φ250 hydrocyclone and the classification concentration is 50%~55%; (4) Carrier mixing flotation: The staged overflow from step (3) and the gold-silver-sulfur concentrate I from step A3 are transferred to the flotation system for two roughing and two cleaning processes to obtain gold-silver-sulfur concentrate II and tailings II; wherein, butyl xanthate 20g / t and pine oil 20g / t are added in roughing process I, butyl xanthate 30g / t and pine oil 10g / t are added in roughing process II, and water glass 500g / t is added in cleaning process I; (5) Strong / weak magnetite mixed magnetic separation: The tailings II from step (4) are roughed and cleaned once using a pulse high gradient magnetic separator to obtain gold-silver-iron concentrate (including magnetite, limonite and siderite) and tailings III; tailings III and tailings I from step (2) are combined into total tailings, which can be directly used as building materials; the operating parameters of the pulse high gradient magnetic separator are: background magnetic field strength 750~900mT, magnetic medium diameter and working gap 2~4mm, pulse intensity 150~180 times / minute, stroke 15~20cm; (6) Mixed roasting: The gold and silver sulfur concentrate II from step (4) and the gold and silver iron concentrate from step (5) are mixed according to the theoretical sulfur content of 28%~35% for roasting feed. After mixing, the mixture is sent to the fine-particle roasting fluidized bed furnace-acid production system for processing. The roasting temperature is controlled at 600~650℃. After roasting, gold and silver roasting residue and sulfuric acid are obtained. (7) Roasting slag water washing-carbon leaching: The gold and silver-containing roasting slag from step (6) is washed and filtered to obtain rinsed slag (to remove soluble sulfates and acids, and to avoid unnecessary consumption of subsequent cyanide reagents) and acidic wastewater; then the rinsed slag is carbon leached to obtain gold and silver-loaded activated carbon and high-quality iron concentrate; wherein, the total liquid-solid ratio in the water washing section is 3:1; in the carbon leaching section, the lime controls the pH to 10.5~11.5, the sodium cyanide concentration is controlled to 0.5‰~0.7‰, and the leaching concentration is 35%~45%.

[0046] (8) Gold and silver refining and casting: The gold and silver loaded activated carbon from step (7) is subjected to traditional desorption-electrowinning-smelting-gold and silver separation-casting to obtain gold and silver ingots.

[0047] The experimental results obtained are as follows: gold recovery rate is 80.45%; silver recovery rate is 76.81%; iron grade of iron concentrate is 60.19% and iron recovery rate is 75.93%; sulfur recovery rate is 85.83%; and the tailings contain 0.15% sulfur and can be used as high-quality building materials.

[0048] In summary, the method described in this invention for treating this type of low-iron, sulfur-containing gold and silver flotation tailings can achieve a gold recovery rate of over 80%; a silver recovery rate of over 75%; an iron grade of over 60% and an iron recovery rate of over 75% in the iron concentrate; a sulfur recovery rate of over 85%; and a sulfur content of less than 0.15% in the tailings, meeting the standards for building sand and allowing for direct use as building materials, thus achieving zero tailings discharge.

[0049] The recovery effects of the method described in this invention compared with the three methods (S1, S2, S3) in the background art are as follows:

[0050] It is evident that the method described in this invention not only significantly outperforms other existing technologies in terms of gold recovery rate, but also simultaneously achieves comprehensive recovery of silver, iron, and sulfur, resulting in remarkable comprehensive resource utilization.

[0051] The present invention has been described in detail above through specific and preferred embodiments. However, those skilled in the art should understand that the present invention is not limited to the embodiments described above. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for efficiently recovering valuable components from low-iron, sulfur-containing gold and silver flotation tailings, characterized in that, Includes the following steps: (1) Selective sorting of materials to be processed: After the materials to be processed are slurried, they are sent to a hydrocyclone separator for sorting to obtain light overflow and heavy sand with a content of -0.037mm accounting for 70%~80%; (2) Light overflow acid activation and flotation, as detailed below: A1: Concentrate the light overflow obtained in step (1) into a concentrated slurry of 60%~65%; A2: Add sulfuric acid to the concentrated slurry from step A1 to adjust the pH to 2-3. Stir for 5-10 minutes, then add dilution water to adjust the slurry concentration to 25%-30% and the pH to 6-6.

5. A3: Transfer the slurry from step A2 into the flotation system for two roughing and two cleaning processes to obtain gold-silver-sulfur concentrate I and tailings I; (3) Heavy sand grinding and classification: The heavy sand from step (1) is ground and classified to obtain a classification overflow with -0.043mm accounting for 80%~85% and a concentration of 30%~35%; (4) Carrier mixing flotation: The staged overflow from step (3) and the gold-silver-sulfur concentrate I from step A3 are transferred into the flotation system for two roughing and two cleaning processes to obtain gold-silver-sulfur concentrate II and tailings II. (5) Strong / weak magnetite mixed magnetic separation: The tailings II from step (4) are roughed and cleaned once using a pulse high gradient magnetic separator to obtain gold, silver and iron concentrate and tailings III; tailings III and tailings I from step (2) are combined into total tailings, which can be directly used as building materials. (6) Mixed roasting: The gold and silver sulfur concentrate II from step (4) and the gold and silver iron concentrate from step (5) are mixed according to the theoretical sulfur content of 28%~35% for roasting feed. After mixing, the mixture is sent to the fine-particle roasting fluidized bed furnace-acid production system for processing to obtain gold and silver roasting slag and sulfuric acid. (7) Roasting residue water washing-carbon leaching: The gold and silver-containing roasting residue from step (6) is washed and filtered to obtain rinsed residue and acidic wastewater; then the rinsed residue is carbon leached to obtain gold and silver-loaded activated carbon and high-quality iron concentrate. (8) Gold and silver refining and casting: The gold and silver loaded activated carbon from step (7) is subjected to traditional desorption-electrowinning-smelting-gold and silver separation-casting to obtain gold and silver ingots.

2. The method for efficiently recovering valuable components from low-iron, sulfur-containing gold and silver flotation tailings according to claim 1, characterized in that, In step (1), the feed concentration of the hydrocyclone separator is 40%~45%, the feed pressure is controlled at 0.035~0.15MPa, and the light overflow of the separator is controlled at 40%~60% of the total feed.

3. The method for efficiently recovering valuable components from low-iron, sulfur-containing gold and silver flotation tailings according to claim 1, characterized in that, The dilution water in step A2 is preferably the overflow water obtained from the concentration in step A1.

4. The method for efficiently recovering valuable components from low-iron, sulfur-containing gold and silver flotation tailings according to claim 1, characterized in that, In step A3, 40-80 g / t butyl xanthate and 20-30 g / t pine oil are added to the first coarse selection, and 20-40 g / t butyl xanthate and 10 g / t pine oil are added to the second coarse selection.

5. The method for efficiently recovering valuable components from low-iron, sulfur-containing gold and silver flotation tailings according to claim 1, characterized in that, In step (3), a φ250 hydrocyclone is used for grading, and the grading concentration is 50%~55%.

6. The method for efficiently recovering valuable components from low-iron, sulfur-containing gold and silver flotation tailings according to claim 4, characterized in that, In step (4), 20-40 g / t butyl xanthate and 10-20 g / t pine oil are added to the first coarse selection, 10-30 g / t butyl xanthate and 10 g / t pine oil are added to the second coarse selection, and 300-500 g / t water glass is added to the first fine selection.

7. The method for efficiently recovering valuable components from low-iron, sulfur-containing gold and silver flotation tailings according to claim 1, characterized in that, In step (5), the background magnetic field strength of the pulse high gradient magnetic separator is 750~900mT, the diameter of the magnetic medium and the working gap are 2~4mm, the pulse intensity is 100~200 times / minute, and the stroke is 15cm~20cm.

8. The method for efficiently recovering valuable components from low-iron, sulfur-containing gold and silver flotation tailings according to claim 1, characterized in that, In step (6), the temperature of the fine-particle calcination fluidized bed furnace is controlled at 600~650℃.

9. The method for efficiently recovering valuable components from low-iron, sulfur-containing gold and silver flotation tailings according to claim 1, characterized in that, In step (7), the total liquid-to-solid ratio in the water washing section is 3:1; in the carbon leaching section, lime is added to control the pH to 10.5~11.5, the sodium cyanide concentration is controlled to 0.5‰~0.7‰, and the leaching concentration is 35%~45%.

Images