Beneficiation method and system for comprehensively recovering gold and silver from low-grade flotation tailings

Abstract

The invention relates to a beneficiation method and system for comprehensively recovering gold and silver from low-grade flotation tailings. The beneficiation method comprises the steps that strong magnetic pre-enrichment is conducted; crushing, grinding and grading; gold and silver flotation; and gold and silver are leached through cyanidation. The system comprises a 1 # stirring barrel, a material port of the 1 # stirring barrel is sequentially connected with a 1 # high-intensity magnetic separator and a 2 # high-intensity magnetic separator through a 1 # ore pulp pump, a concentrate outlet of the 2 # high-intensity magnetic separator is connected with a feeding port of a 1 # thickener, an underflow port of the 1 # thickener is connected with a feeding port of a grading cyclone through a 1 # ore pulp pool and a 2 # ore pulp pump, and a sand settling port and an overflow port of the grading cyclone are connected with a ball mill and a feeding port of the 2 # stirring barrel respectively. A discharge port of the ball mill is connected with a feed port of the 1 # ore pulp tank, a discharge port of the 2 # stirring barrel is connected with the flotation system, the flotation system is connected with the 2 # thickener through the 2 # ore pulp tank and the 3 # ore pulp pump, an underflow port of the 2 # thickener is connected with a feed port of the filter press through the 3 # ore pulp tank and the 4 # ore pulp pump, and the filter press is connected with the cyanidation leaching system through the 3 # stirring barrel. According to the method, efficient recovery of gold and silver from low-grade and complex-component flotation tailings is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of tailings recovery, and particularly relates to a beneficiation method and system for comprehensively recovering gold and silver from low-grade flotation tailings. Background Art

[0002] Today, with the increasing shortage of mineral resources and the prominent environmental problems, the secondary recovery and utilization of valuable metals in resources such as tailings and smelting slag have attracted increasing attention. The recovery and utilization of tailings resources have become an important issue for the sustainable development of the current mine economy, and the research on the reduction, resource utilization and safety of tailings resources is of great significance.

[0003] At present, the recovery of gold and silver in flotation tailings mainly adopts flotation method, leaching method and gravity separation method. In recent years, with the progress of technology, the flotation method and leaching method have been widely used in tailings recovery, but the recovery rate still needs to be improved. Especially for tailings with low gold and silver grades and complex compositions, problems such as high recovery difficulty, poor recovery effect, difficulty in obtaining qualified products and high recovery cost are more prominent. For example, the invention patent disclosed in CN104841565 A, a method for recovering gold from gold flotation tailings, includes: grinding the flotation tailings, the particle size of the material after grinding is not more than 0.074mm, adjusting the material concentration to 40%, adjusting the pH value to 8-12 by adding lime, and then adding emulsifier, flocculant, collector and frother for flotation to obtain gold concentrate products. This patent uses the flotation method to achieve more than 70% gold recovery in gold flotation tailings, but the gold grade in the gold flotation tailings targeted by this method is high, above 1.2g / t, and the gold grade in the gold concentrate obtained under this high grade is only about 20%. It can be inferred that if it is applied to flotation tailings with a gold grade far lower than 1.2g / t, the recovery effect will be worse. In addition, the gravity separation method separates gold and silver from other minerals by using the density difference, which is suitable for tailings with coarser gold particles, but has a poor recovery effect on fine-grained gold. However, gold and silver in flotation tailings usually exist in the form of fine-grained dissemination, so it is not applicable. Summary of the Invention

[0004] Based on the above problems, the invention provides a beneficiation method and system for comprehensively recovering gold and silver from low-grade flotation tailings.

[0005] Among them, a beneficiation method for comprehensively recovering gold and silver from low-grade flotation tailings provided by the invention includes the following steps: (1) High-intensity magnetic pre-concentration: performing one-time high-intensity magnetic roughing and one-time high-intensity magnetic cleaning on the low-grade flotation tailings, removing gangue minerals, slimes and other non-magnetic substances that interfere with flotation and leaching, improving the feed grade of the subsequent beneficiation system, obtaining gold and silver-containing high-intensity magnetic concentrate and magnetic separation tailings, and directly discharging the magnetic separation tailings into the tailings pond for stacking; Before flotation, this step removes 75% - 79% of gangue minerals, slimes, and other substances that interfere with the flotation and cyanidation leaching of gold and silver from low-grade flotation tailings through two-stage high-intensity magnetic separation, improving the feed grade of the subsequent beneficiation system, reducing the ore volume processed in subsequent operations, and creating a good foundation for subsequent flotation and leaching of gold and silver. Among them, clay slimes, due to their large specific surface area, are easily adsorbed on the surface of valuable minerals and flotation bubbles during flotation, affecting flotation indexes and consuming a large amount of flotation reagents; sulfides, especially copper sulfide minerals, will be enriched in the gold concentrate product during flotation, and during cyanidation leaching, copper ions will consume a large amount of cyanide, increasing the reagent cost. Therefore, the removal of these substances can significantly reduce the impact on the flotation and leaching processes.

[0006] (2)Crushing, grinding, and classification: After concentrating the gold and silver-bearing high-intensity magnetic concentrate obtained in step (1), through crushing, grinding, and classification, qualified materials with more than 80% passing - 0.043mm and coarse-grained materials are obtained, and the coarse-grained materials are returned to the ball mill for re-grinding; Crushing, grinding, and classification are carried out before flotation to fully dissociate the gold and silver-bearing high-intensity magnetic concentrate, enable the flotation reagents to act effectively on the mineral surface, and improve flotation selectivity.

[0007] (3)Flotation of gold and silver: Transfer the qualified materials obtained in step (2) into the flotation system, and after one rough selection, three cleanings, and two scavengings, flotation gold concentrate and flotation tailings are obtained. The flotation tailings are directly discharged into the tailings pond for stacking; This step further enriches and improves the grade of the gold concentrate through multi-stage flotation, and separates 96% - 98% of gangue minerals and other interfering substances in the feed into the tailings, improving the efficiency and effect of subsequent cyanidation leaching.

[0008] (4)Cyanidation leaching of gold and silver: After concentrating and pressure-filtering the flotation gold concentrate obtained in step (3), adjust the pulp pH to 12, add sodium cyanide for cyanidation leaching for 32 - 36h, to obtain pregnant solution and cyanidation residue. The pregnant solution is processed through activated carbon adsorption, desorption, electrolysis, and refining to obtain gold concentrate (this part belongs to the conventional process and will not be elaborated here).

[0009] The purpose of thickening and pressure-filtering before cyanidation leaching in this step: First, return the filtrate in the flotation gold concentrate to the flotation section for recycling, and the flotation reagents in the filtrate can be fully utilized; Second, avoid the flotation reagents entering the cyanidation leaching section, causing the activated carbon to be "poisoned" and affecting the adsorption effect of gold and silver.

[0010] Furthermore, in step (1), the pulp concentration for the two-stage high-intensity magnetic separation is 31% - 33%, and the magnetic induction intensities for high-intensity magnetic roughing and high-intensity magnetic cleaning are 0.8T and 0.6T respectively.

[0011] Furthermore, in step (2), the pulp concentration of the thickened underflow is 50% - 60%.

[0012] Further, 500 - 600 g / t of sodium carbonate as regulator is added during grinding in step (2).

[0013] Further, collector sodium butyl xanthate and frother pine oil alcohol are added in rough selection, first scavenging and second scavenging in step (3), and 120 - 180 g / t of sodium butyl xanthate and 40 - 60 g / t of pine oil alcohol are added in total in the three flotation processes.

[0014] Further, the dosage of sodium cyanide in step (4) is 3 - 3.5 kg / t.

[0015] The present invention also provides a system for the ore dressing method for comprehensively recovering gold and silver from the above - mentioned low - grade flotation tailings, including a No. 1 stirring tank. The discharge port of the No. 1 stirring tank is sequentially connected to a No. 1 high - intensity magnetic separator and a No. 2 high - intensity magnetic separator through a No. 1 pulp pump. The concentrate outlet of the No. 2 high - intensity magnetic separator is connected to the feed inlet of a No. 1 thickener. The underflow port of the No. 1 thickener is connected to the feed inlet of a hydrocyclone through a No. 1 pulp sump and a No. 2 pulp pump. The sand outlet and the overflow outlet of the hydrocyclone are respectively connected to the feed inlets of a ball mill and a No. 2 stirring tank. The discharge outlet of the ball mill is connected to the feed inlet of the No. 1 pulp sump. The discharge outlet of the No. 2 stirring tank is connected to a flotation system. The flotation system is connected to a No. 2 thickener through a No. 2 pulp sump and a No. 3 pulp pump. The underflow port of the No. 2 thickener is connected to the feed inlet of a filter press through a No. 3 pulp sump and a No. 4 pulp pump. The filter press is connected to a cyanidation leaching system through a No. 3 stirring tank.

[0016] Further, the flotation system includes one flotation roughing machine, three flotation cleaning machines and two flotation scavenging machines.

[0017] Further, the cyanidation leaching system includes a plurality of leaching tanks connected in series.

[0018] The beneficial effects of the present invention: Before flotation, the present invention first uses two - stage high - intensity magnetic separation to enrich the flotation tailings, removing 75% - 79% of gangue minerals, slimes and other interfering substances, greatly improving the feed grade of the subsequent flotation. Then, a crushing, grinding and classification closed - circuit system is adopted to fully dissociate the gold - and silver - containing high - intensity magnetic concentrate, creating good feed conditions for flotation. Subsequently, through one rough selection, three cleanings and two scavengings, the concentrate grade is further improved, and the rejection rate of gangue minerals, slimes and other interfering substances reaches 96% - 98%, thus ensuring the cyanidation leaching efficiency and effect, realizing the efficient recovery of gold and silver from low - grade and complex - component flotation tailings, and the gold recovery rate reaches more than 90% and the silver recovery rate reaches more than 60%. In addition, this method fully removes interfering substances before flotation and leaching, which can not only improve the flotation and leaching indexes, but also reduce the consumption of flotation reagents and cyanidation reagents, having significant economic benefits. Description of the Drawings

[0019] Figure 1 is the flow chart of the ore dressing method of the present invention; Figure 2 is the equipment connection diagram of the ore dressing system of the present invention; In the figure: 1-1# agitation tank, 2-1# pulp pump, 3-1# high-intensity magnetic separator, 4-2# high-intensity magnetic separator, 5-1# thickener, 6-1# pulp sump, 7-2# pulp pump, 8-classifying cyclone, 9-ball mill, 10-2# agitation tank, 11-flotation system, 12-2# pulp sump, 13-3# pulp pump, 14-2# thickener, 15-3# pulp sump, 16-4# pulp pump, 17-filter press, 18-3# agitation tank, 19-cyanidation leaching system. Specific embodiments

[0020] In order to make the technical problems and technical 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 only used to explain the present invention and are not used to limit the present invention. Embodiment 1

[0021] Raw ore 1#: A low-grade flotation tailing, the main elements are silicon, calcium, magnesium, aluminum, gold, silver and iron, where iron mainly exists in the forms of hematite, siderite and iron silicate; gold and silver are in fine-grained dissemination, mainly disseminated in hematite and siderite; the main gangue minerals are quartz, calcite, ankerite, dolomite of carbonate class and a small amount of garnet, biotite, diopside, etc. Among them, the total iron grade is 13.98%, the gold grade is 0.21 g / t, the silver grade is 2.04 g / t, and the copper grade is 0.046%.

[0022] As Figure 1 shown, the method of the present invention is used to recover raw ore 1#, and the specific steps are as follows: (1) High-intensity magnetic pre-concentration: Conduct one-stage high-intensity magnetic roughing and one-stage high-intensity magnetic cleaning on the low-grade flotation tailing, remove the gangue minerals, slime and other non-magnetic substances that interfere with flotation and leaching therein, improve the feed grade of the subsequent ore dressing system, obtain the gold-silver-containing high-intensity magnetic concentrate and the magnetic separation tailing, and the magnetic separation tailing is directly discharged into the tailing pond for storage; during this process, the pulp concentration of the two-stage high-intensity magnetic separation is about 32%, and the magnetic induction intensities of the high-intensity magnetic roughing and high-intensity magnetic cleaning are 0.8 T and 0.6 T respectively.

[0023] (2) Crushing, grinding and classification: After concentrating the gold-silver-containing high-intensity magnetic concentrate obtained in step (1), the concentration of the thickened underflow is about 53%, and it is transferred to a classifying cyclone and a ball mill for crushing, grinding and classification to obtain qualified materials with more than 80% of -0.043 mm and coarse-grained materials, and the coarse-grained materials are returned to the ball mill for re-grinding; among them, 550 g∕t of the regulator sodium carbonate is added during grinding.

[0024] (3) Flotation of gold and silver: Transfer the qualified materials obtained in step (2) to the flotation system. After one rough selection, three fine selections, and two scavenging selections, flotation gold concentrate and flotation tailings are obtained. The flotation tailings are directly discharged into the tailings pond for stacking. During this process, the addition amounts of the collector sodium butyl xanthate in rough selection, scavenging selection 1, and scavenging selection 2 are 80 g / t, 40 g / t, and 20 g / t respectively, and the addition amounts of the frother pine oil are 20 g / t, 10 g / t, and 10 g / t respectively. (4) Cyanidation leaching of gold and silver: After concentrating and pressure filtering the flotation gold concentrate obtained in step (3), adjust the pulp pH to 12, add 3 kg / t of sodium cyanide for cyanidation leaching for 32 h to obtain pregnant solution and cyanidation slag. The pregnant solution is adsorbed by activated carbon, desorbed, electrolyzed, and refined to obtain gold concentrate.

[0025] The process indexes for treating the original ore 1# by the above method are shown in Table 1: Table 1: Process indexes of the original ore 1# Example 2

[0026] Original ore 2#: A low-grade flotation tailing, the main elements are silicon, calcium, magnesium, manganese, gold, silver, and iron, among which iron mainly exists in the forms of limonite, siderite, and ferrosilicate; gold and silver are disseminated in fine particles, mainly disseminated in limonite and siderite; the main gangue minerals are quartz, calcite, ankerite, dolomite of carbonate class, and a small amount of garnet, biotite, diopside, etc. Among them, the total iron grade is 15.36%, the gold grade is 0.29 g / t, the silver grade is 3.25 g / t, and the copper grade is 0.073%.

[0027] As Figure 1 shown, the method of the present invention is used to recover the original ore 2#, and the specific steps are as follows: (1) High-intensity magnetic pre-concentration: Conduct one high-intensity magnetic rough selection and one high-intensity magnetic fine selection on the low-grade flotation tailing to remove the gangue minerals, slime, and other non-magnetic substances that interfere with flotation and leaching, improve the feed grade of the subsequent beneficiation system, and obtain high-intensity magnetic concentrate containing gold and silver and magnetic separation tailings. The magnetic separation tailings are directly discharged into the tailings pond for stacking. During this process, the pulp concentration of the two high-intensity magnetic separations is about 32%, and the magnetic induction intensities of high-intensity magnetic rough selection and high-intensity magnetic fine selection are 0.8 T and 0.6 T respectively.

[0028] (2) Crushing, grinding, and classification: After concentrating the high-intensity magnetic concentrate containing gold and silver obtained in step (1), the concentration of the thickened underflow is about 55%. Transfer it to a hydrocyclone and a ball mill for crushing, grinding, and classification to obtain qualified materials with more than 80% -0.043 mm and coarse-grained materials. The coarse-grained materials are returned to the ball mill for re-grinding. Among them, 570 g / t of the regulator sodium carbonate is added during grinding.

[0029] (3)Flotation of gold and silver: Transfer the qualified materials obtained in step (2) to the flotation system. After one rough selection, three fine selections, and two scavenging selections, flotation gold concentrate and flotation tailings are obtained. The flotation tailings are directly discharged into the tailings pond for stacking. During this process, the addition amounts of butyl xanthate as the collector in rough selection, scavenging selection 1, and scavenging selection 2 are 82 g / t, 40 g / t, and 20 g / t respectively, and the addition amounts of pine oil as the frother are 20 g / t, 10 g / t, and 10 g / t respectively. (4)Cyanidation leaching of gold and silver: After concentrating and pressure filtering the flotation gold concentrate obtained in step (3), adjust the pulp pH to 12, add 3.5 kg / t of sodium cyanide for cyanidation leaching for 36 h to obtain pregnant solution and cyanidation slag. The pregnant solution is processed through activated carbon adsorption, desorption, electrolysis, and refining to obtain gold concentrate.

[0030] The process indexes for processing the original ore #2 using the above method are shown in Table 2: Table 2: Process indexes of the original ore #2

[0031] Based on the above embodiments, when using the method described in the present invention to recover gold and silver from this type of low-grade flotation tailings, the gold recovery rate can reach over 90%, and the silver recovery rate can reach over 60%. The gold grade is increased from the original 0.2 - 0.3 g / t to 13 - 18 g / t, and the silver grade is increased from the original 2.0 - 3.5 g / t to 28 - 45.5 g / t. It can be seen that this method has a good recovery effect on such low-grade flotation tailings and has guiding significance for the recovery of low-grade and complex-component flotation tailings. Example 3

[0032] This embodiment provides a beneficiation system for comprehensively recovering gold and silver from low-grade flotation tailings, including a #1 agitation tank 1. The discharge port of the #1 agitation tank 1 is sequentially connected to a #1 high-intensity magnetic separator 3 and a #2 high-intensity magnetic separator 4 through a #1 slurry pump 2. The concentrate outlet of the #2 high-intensity magnetic separator 4 is connected to the feed inlet of a #1 thickener 5. The underflow port of the #1 thickener 5 is connected to the feed inlet of a hydrocyclone 8 through a #1 slurry sump 6 and a #2 slurry pump 7. The sand outlet and overflow outlet of the hydrocyclone 8 are respectively connected to the feed inlets of a ball mill 9 and a #2 agitation tank 10. The discharge outlet of the ball mill 9 is connected to the feed inlet of the #1 slurry sump 6. The discharge outlet of the #2 agitation tank 10 is connected to a flotation system 11. The flotation system is connected to a #2 thickener 14 through a #2 slurry sump 12 and a #3 slurry pump 13. The underflow port of the #2 thickener is connected to the feed inlet of a filter press 17 through a #3 slurry sump 15 and a #4 slurry pump 16. The filter press 17 is connected to a cyanidation leaching system 19 through a #3 agitation tank 18.

[0033] The above flotation system 11 includes one flotation roughing machine, three flotation cleaning machines, and two flotation scavenging machines; the cyanidation leaching system 18 includes multiple series-connected leaching tanks.

[0034] It should be noted that the above-mentioned devices are all existing devices. This application only involves the application of these existing devices and does not involve the improvement of their structures.

[0035] When the above system is used to recover gold and silver from low-grade flotation tailings, the specific working principle is as follows: (1) High-intensity magnetic pre-concentration: The low-grade flotation tailings are added to the 1# agitation tank 1 for pulp adjustment to a concentration of 31% - 33%, and then transported by the 1# pulp pump 2 to the 1# high-intensity magnetic separator 3 for rough selection. The concentrate obtained from the rough selection is further transferred to the 2# high-intensity magnetic separator 4 for fine selection. The concentrate magnetically separated by the 2# high-intensity magnetic separator 4 is the gold and silver-containing high-intensity magnetic concentrate, while the magnetic tailings discarded by the 1# high-intensity magnetic separator 3 and the 2# high-intensity magnetic separator 4 are mainly gangue minerals, slime, and other non-magnetic substances that interfere with flotation and leaching. In this way, the tailings are pre-concentrated through two high-intensity magnetic separations to improve the feed grade of the subsequent flotation or leaching beneficiation system.

[0036] (2) Crushing, grinding, and classification: The gold and silver-containing high-intensity magnetic concentrate obtained in step (1) is transferred to the 1# thickener 5 for thickening until the underflow concentration reaches 50% - 60%. The underflow pulp is transferred to the 1# pulp sump 6 for buffering, and then pumped by the 2# pulp pump 7 to the classification cyclone 8 for classification, obtaining qualified materials with more than 80% of -0.043mm and coarse-grained materials. The coarse-grained materials are transferred from the sand discharge port of the classification cyclone 8 to the ball mill 9 for re-grinding. The re-ground materials are transferred to the 1# pulp sump 6 for buffering and then pumped by the 2# pulp pump 7 to the classification cyclone 8 for classification again. This cycle continues until all materials are crushed and ground into qualified materials.

[0037] (3) Flotation of gold and silver: The qualified materials obtained in step (2) are transferred from the overflow port of the classification cyclone 8 to the 2# agitation tank 10 for pulp adjustment to a concentration of 35% - 37%, and then transferred to the flotation system 11. After one rough selection, three fine selections, and two scavenging selections (this part is a conventional process and will not be elaborated here), flotation gold concentrate and flotation tailings are obtained. The flotation tailings are directly discharged into the tailings pond for stacking.

[0038] (4) Cyanide leaching of gold and silver: The flotation gold concentrate obtained in step (3) is transferred from the concentrate outlet of the third cleaner to the 2# pulp sump 12 for buffering, and then transported by the 3# pulp pump 13 to the 2# thickener 14 for thickening; after thickening, it is transferred to the 3# pulp sump 15 for buffering, and then transported by the 4# pulp pump 16 to the filter press 17 for pressure filtration. The filter cake obtained from the pressure filtration is further transferred to the 3# agitation tank for pulp adjustment to a concentration of 30% - 33%, and then transferred to the cyanide leaching system 18 for cyanide leaching, obtaining pregnant solution and cyanide slag.

[0039] The present invention has been described in detail through specific and preferred embodiments. However, those skilled in the art should understand that the present invention is not limited to the above-described embodiments. Any modifications, equivalent substitutions, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A beneficiation method for comprehensive recovery of gold and silver from low-grade flotation tailings, characterized in that: The steps include: (1) Strong magnetic pre-enrichment: The low-grade flotation tailings are subjected to a strong magnetic roughing and a strong magnetic concentration to remove gangue minerals, ore mud and other non-magnetic materials that interfere with flotation and leaching, thereby improving the feed grade of the subsequent beneficiation system, and obtaining strong magnetic concentrates containing gold and silver and magnetic tailings. The magnetic tailings are directly discharged into the tailings pond for storage; (2) Crushing and classification: After the gold-silver-containing strong magnetic concentrate obtained in step (1) is concentrated, it is crushed and classified to obtain qualified materials with a particle size of -0.043 mm accounting for more than 80% and coarse particles. The coarse particles are returned to the ball mill for further grinding; (3) Flotation of gold and silver: The qualified materials obtained in step (2) are transferred to the flotation system, and after a roughing separation, a third cleaning separation and a second scavenging separation, flotation gold concentrate and flotation tailings are obtained. The flotation tailings are directly discharged into the tailings pond for storage; (4) Cyanide leaching of gold and silver: The flotation gold concentrate obtained in step (3) is concentrated and filtered, the pH value of the slurry is adjusted to 12, and sodium cyanide is added for cyanide leaching for 32 to 36 hours to obtain precious liquid and cyanide slag. The precious liquid is adsorbed on activated carbon, desorbed, electrolyzed, and refined to obtain gold concentrate.

2. The method for comprehensive recovery of gold and silver from low-grade flotation tailings according to claim 1, characterized in that: The ore pulp concentration of the two strong magnetic separations in step (1) is 31% to 33%, and the magnetic induction intensities of the strong magnetic roughing separation and the strong magnetic concentration are 0.8T and 0.6T respectively.

3. The ore dressing method for comprehensive recovery of gold and silver from low-grade flotation tailings according to claim 1 is characterized in that: The concentration of the concentrated underflow slurry in step (2) is 50% to 60%.

4. The ore dressing method for comprehensive recovery of gold and silver from low-grade flotation tailings according to claim 1 is characterized in that: In step (2), 500-600 g / t of sodium carbonate as a conditioning agent is added during grinding.

5. The method for comprehensive recovery of gold and silver from low-grade flotation tailings according to claim 1, characterized in that: In step (3), sodium butyl xanthate as a collector and pine oil as a frother are added to the roughing, scavenging first and scavenging second flotation steps, and a total of 120-180 g / t of sodium butyl xanthate and 40-60 g / t of pine oil are added to the three flotation steps.

6. The method for comprehensive recovery of gold and silver from low-grade flotation tailings according to claim 1, characterized in that: The amount of sodium cyanide used in step (4) is 3 to 3.5 kg / t.

7. A beneficiation system for comprehensive recovery of gold and silver from low-grade flotation tailings, characterized in that: The invention comprises a 1# stirring barrel (1), wherein the discharge port of the 1# stirring barrel (1) is connected to a 1# high-intensity magnetic separator (3) and a 2# high-intensity magnetic separator (4) in sequence through a 1# slurry pump (2), the concentrate outlet of the 2# high-intensity magnetic separator (4) is connected to the feed port of a 1# thickener (5), the underflow port of the 1# thickener (5) is connected to the feed port of a classifying cyclone (8) through a 1# slurry pool (6) and a 2# slurry pump (7), and the sand settling port and the overflow port of the classifying cyclone (8) are respectively connected to a ball mill (9) and a 2# stirring barrel (10). The feed inlet of the ball mill (9) is connected to the feed inlet of the 1# slurry pool (6), the discharge port of the 2# stirring barrel (10) is connected to the flotation system (11), the flotation system is connected to the 2# thickener (14) via the 2# slurry pool (12) and the 3# slurry pump (13), the underflow port of the 2# thickener is connected to the feed inlet of the filter press (17) via the 3# slurry pool (15) and the 4# slurry pump (16), and the filter press (17) is connected to the cyanide leaching system (19) via the 3# stirring barrel (18).

8. The ore dressing system for comprehensive recovery of gold and silver from low-grade flotation tailings according to claim 7 is characterized in that: The flotation system (11) comprises a flotation rougher, three flotation cleaners, and two flotation sweepers.

9. A beneficiation system for comprehensive recovery of gold and silver from low-grade flotation tailings according to claim 7 or 8, characterized in that: The cyanide leaching system (19) comprises a plurality of leaching tanks connected in series.

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