A method for comprehensively recovering gold, silver and iron by co-roasting pyrite to treat gold extraction waste residue

Abstract

The present invention belongs to the technical field of comprehensive utilization of metallurgical tailings resources, and relates to a method for comprehensive recovery of gold, silver and iron by co-roasting treatment of pyrite with gold extraction waste slag, comprising the following steps: 1) batching fine grinding for gold extraction treatment; 2) low-temperature reduction roasting; 3) flotation enrichment of gold, silver and copper; 4) high-temperature reduction roasting and magnetic separation of iron. According to the characteristics of low-gold pyrite and cyanidation gold extraction waste slag, the present invention adopts the idea of ​​"roasting waste treatment, gold and silver cascade recovery, and comprehensive recovery of iron" through a multi-stage treatment process, mainly adopts batching fine grinding gold extraction treatment technology, low-temperature reduction roasting technology, flotation enrichment of gold, silver and copper technology, and high-temperature reduction roasting and magnetic separation of iron technology, and synergistically performs deep treatment of cyanide-containing waste slag in gold mines, combines roasting of low-gold pyrite with purification and treatment of gold extraction slag, and realizes comprehensive recovery of gold, silver and iron in pyrite and cyanidation waste slag; the treatment effect is good, the efficiency is high, the system operation is stable, the process flow is simple, and it is easy to realize industrial application.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive utilization of metallurgical tailings resources, and in particular relates to a method for comprehensively recovering gold, silver and iron from gold-extracting waste slag by co-roasting pyrite. Background Art

[0002] In the gold smelting industry, cyanidation is generally used to extract gold, which is divided into direct cyanidation, roasting cyanidation, two-stage roasting cyanidation, bacterial oxidation cyanidation, hot-pressing oxidation cyanidation, etc. Direct cyanidation can only process gold ores with less harmful elements and higher gold and silver leaching rates; bacterial oxidation cyanidation and hot-pressing oxidation cyanidation have high production and processing costs and poor adaptability to gold ores. Currently, only a few companies have industrialized applications and the production scale is relatively low.

[0003] At present, roasting cyanidation process is the most effective, mature and economical process for processing complex multi-metallic gold-containing materials. Although roasting cyanidation process can recycle sulfur in gold ore through roasting treatment and recover gold and silver in it through cyanidation treatment, the tailings after cyanidation gold extraction still contain about 2g / t gold, about 40g / t silver, about 35% iron, etc. These metal elements cannot be effectively recovered, resulting in a waste of valuable resources.

[0004] In recent years, many researchers have studied how to recover valuable metals from cyanide tailings. Cyanide tailings are difficult to beneficiate. In addition, sodium cyanide, lime, sodium hydroxide, sodium carbonate and other reagents are added to cyanide tailings during the production process. After a long period of cyanidation treatment, the properties of the mineral surface have changed significantly. In addition, the strong inhibitory effect of cyanide on various metal minerals makes the flotation of cyanide tailings more difficult. Since cyanide tailings often contain a lot of residual reagents, which greatly interferes with flotation, the properties of the ore are relatively complex, and the ore particle size is also extremely fine. Finding suitable flotation reagents is the biggest problem at present. Researchers have done a lot of research on reagents for flotation gold extraction from cyanide tailings. Collectors are mainly concentrated in yellow medicine, black medicine, sulfur and nitrogen, etc., and inhibitors are mainly concentrated in water glass, sodium hexametaphosphate, tannin, etc. From the existing research analysis, it is found that it is difficult for conventional single collectors to take into account both selectivity and collection capacity at the same time. The use of a single inhibitor also has the problem of unsatisfactory inhibition effect, and the flotation recovery effect of gold and silver is poor.

[0005] The Chinese invention patent with the patent number of 201410678782.4 discloses a method for recovering gold from cyanide tailings by branched series flow flotation, which mainly includes the following steps: pulp pretreatment, using sodium carbonate and ferrous sulfate as pulp adjusters; kerosene flotation decarbonization; split flow slurry adjustment: the decarbonized pulp flows to the stirring distribution tank, and the stirring distribution tank evenly distributes the pulp to two slurry adjustment barrels for slurry adjustment; branched series flow flotation: all the foam products of roughing selection 1 enter roughing selection 2 for flotation together with the decarbonized pulp, and the foam products of roughing selection 2 are subjected to closed-circuit selection operations of selection 1 and selection 2 to obtain gold concentrate, and no reagents are added in this selection stage; the product in the tank of roughing selection 1 is subjected to closed-circuit scavenging of scavenging selection 1 and scavenging selection 2 to obtain tailings. The applicability of this invention is limited to full-mud cyanide tailings, and the step-by-step flotation process is used to produce carbon-containing gold concentrate and gold concentrate, and the process is complicated. In addition, the further treatment and purification methods of the enriched gold concentrate and the carbon-containing gold concentrate are not described in detail.

[0006] In addition, since the cyanide gold extraction tailings also contain some heavy metal ions, cyanide and residual flotation reagents, the "National Hazardous Waste List" stipulates that the cyanide gold extraction tailings after cyanide leaching and gold extraction are inorganic cyanide wastes (code HW33092~003~33), and their long-term large-scale storage will cause environmental pollution. Therefore, it is of great significance to cleanly treat, non-waste disposal and comprehensive utilization of gold extraction waste. Summary of the invention

[0007] In view of the deficiencies in the above-mentioned prior art, the present invention provides a method for comprehensively recovering gold, silver and iron from low-gold pyrite and cyanide waste residue by co-roasting pyrite. The method has a simple process flow and high treatment efficiency, and can achieve comprehensive recovery of gold, silver and iron from low-gold pyrite and cyanide waste residue.

[0008] The specific technical solutions of the present invention are as follows:

[0009] A method for comprehensively recovering gold, silver and iron by co-roasting pyrite to treat gold extraction waste residue, comprising the following steps:

[0010] 1) Fine grinding and gold extraction treatment: Grind and mix the gold-containing low-gold pyrite and the gold-containing gold extraction waste slag evenly, and add soda ash at the same time; adjust the slurry concentration to 30-35wt% with water after grinding, and stir for 6-10h; then add activated carbon and stir for 4-6h; then sieve to obtain the gold-loaded activated carbon on the sieve and the mixed slurry under the sieve; dehydrate the mixed slurry under the sieve to obtain sulfur-containing ore powder;

[0011] 2) Low-temperature reduction roasting: the sulfur-containing ore powder obtained in step 1) is fed into a secondary fluidized bed roasting furnace, and a reducing roasting atmosphere is maintained, and the roasting produces flue gas and low-temperature reduction roasted sand;

[0012] 3) Flotation enrichment of gold, silver and copper: The low-temperature reduced roasted sand produced in step 2) is wet-ground, sodium sulfide and lead nitrate are added and stirred for 20 to 40 minutes, and then butyl xanthate and 25# black medicine are added as collectors. The process is a roughing selection, a scavenging selection and a four-selection selection process, and the flotation enrichment concentrate and flotation tailings are produced by flotation.

[0013] 4) High-temperature reduction roasting and magnetic iron separation: After dehydration and filter pressing of the flotation tailings produced in step 3), calcium oxide and coal gangue are added, mixed, pelletized, and reduced and roasted in a rotary kiln. After roasting, the pellets are quenched with water, rapidly cooled, ball milled, and slurried, and then transported to a magnetic separator to produce iron concentrate and magnetic tailings through magnetic separation.

[0014] According to the characteristics that cyanide-containing waste residue contains multiple pollutants such as cyanide, arsenic and heavy metals, the present invention firstly adopts the primary batching fine grinding gold extraction treatment technology, mixing low-gold pyrite with cyanide-containing waste residue, grinding, stirring, carbon leaching, separation, and filter pressing to obtain gold-carrying carbon and sulfur-containing ore powder; the secondary low-temperature reduction roasting technology, feeding the sulfur-containing ore powder into a secondary boiling roasting furnace, maintaining a reduction roasting atmosphere, and sulfur dioxide flue gas can be produced by traditional sulfuric acid production technology to produce industrial sulfuric acid, and synchronous roasting is used to remove pollutants such as cyanide, arsenic and heavy metals; the third The first-level roasted sand fine grinding gold, silver and copper flotation process, the roasted sand is wet ground, stirred, and floated to enrich gold, silver and copper to obtain flotation concentrate and flotation tailings; the fourth-level batching high-temperature reduction roasting magnetic separation technology, the flotation tailings are mixed by a mixer, balled, reduced and roasted, the roasted ore is finely ground, and the iron concentrate is recovered through a magnetic separation process. The output magnetic separation tailings are identified as general solid waste containing 60-70wt% silicon dioxide, which is used as raw material for building materials production, realizing the clean treatment of pyrite and gold extraction waste slag and the comprehensive recovery and utilization of gold, silver and iron resources.

[0015] Furthermore, in the step 1), the amount of soda ash added is 5-10wt% based on the total mass of the gold-containing low-gold pyrite and the gold-containing gold extraction waste slag; the grinding fineness after grinding is -400 mesh 98-100%; and the activated carbon particle size is +20 mesh 98%.

[0016] By adopting the above further technical features, the mixed slurry can be dehydrated to obtain sulfur-containing ore powder with a water content of 8-12wt%, a gold content of 1-2g / t, a silver content of 30-40g / t, a sulfur content of 25-30wt%, and an iron content of 30wt%.

[0017] Furthermore, in the step 2), the roasting temperature is 450-550° C.; the oxygen supply during roasting is 91-95% of the total oxygen required for the complete combustion of the materials; and the roasting time is 50-70 min.

[0018] By adopting the above-mentioned further technical features, pollutants such as cyanide, arsenic and heavy metals can be removed by roasting; low-temperature reduction roasted sand containing 1.5-2.5g / t of gold, 40-50g / t of silver and 40-50% of iron can be produced; among which, the flue gas containing sulfur dioxide, sulfur trioxide, fine-grained mineral dust, etc. produced by roasting can be purified, converted, absorbed and other processes of traditional acid production process to produce industrial sulfuric acid products.

[0019] Furthermore, in the step 3), the grinding fineness after wet grinding is -400 mesh 90 to 95%.

[0020] Furthermore, in the step 3), based on the mass of low-temperature reduced roasted sand, the amount of sodium sulfide added is 500-1000 g / t, the amount of lead nitrate added is 200-300 g / t; the amount of collector butyl xanthate added is 800-1600 g / t, and the amount of 25# black medicine added is 300-500 g / t.

[0021] Furthermore, in the step 3), the total flotation time is 30 to 60 minutes.

[0022] By adopting the above further technical characteristics, flotation can produce flotation enriched concentrate containing 15-25g / t gold, 300-500g / t silver, and 3-6% copper, and flotation tailings containing 0.30-0.50g / t gold, 3-5g / t silver, and 43-53% iron; after dehydration and filtration, the flotation tailings have a moisture content of 8-10%.

[0023] Furthermore, in the step 4), based on the mass of the flotation tailings, the amount of calcium oxide added is 8-12wt%, and the amount of coal gangue added is 8-12wt%.

[0024] Furthermore, in the step 4), a disc ball making machine is used to make pellets, and the diameter of the pellets is 5 to 7 mm.

[0025] Furthermore, in the step 4), the oxygen supply in the rotary kiln is 85-95% of the total oxygen required for the complete combustion of the materials, the roasting temperature is 950-1050° C., and the roasting time is 60-90 min.

[0026] Furthermore, in the step 4), the fineness after ball milling (-200 mesh) is 85-95%; and the concentration of the slurry after slurry adjustment is 20-30wt%.

[0027] Furthermore, in the step 4), the slurry flow rate transported to the magnetic separator is 20-30 t / h, and the magnetic field strength is 100-120 mT.

[0028] By adopting the above further technical features, iron concentrate containing 70-80wt% iron and 0.3-0.5wt% sulfur can be produced after magnetic separation, and the iron recovery rate is 90-95%. The magnetic separation tailings are general solid waste containing 60-70% silicon dioxide, which can be used as raw materials for building materials production, realizing the clean treatment of pyrite and gold extraction waste slag and the comprehensive recovery and utilization of gold, silver and iron resources.

[0029] The beneficial effects of the present invention are:

[0030] (1) According to the characteristics of low-gold pyrite and cyanide gold extraction waste residue, the present invention adopts a multi-stage treatment process of "roasting waste treatment, step-by-step recovery of gold and silver, and comprehensive recovery of iron", combines the roasting of low-gold pyrite with the purification and treatment of gold extraction slag, and realizes the comprehensive recovery of gold, silver and iron in pyrite and cyanide waste residue.

[0031] (2) The present invention mainly adopts the technology of fine grinding and gold extraction, low-temperature reduction and roasting technology, flotation enrichment of gold, silver and copper technology, and high-temperature reduction and roasting magnetic separation technology to coordinately carry out deep treatment of cyanide-containing waste residues in gold mines. The treatment effect is good and the efficiency is high. The system operation is stable and the process flow is simple, which is easy to realize industrial application. After treatment, iron concentrate is produced, and the tailings after magnetic separation are used as raw materials for building materials production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a flow chart of a method for comprehensively recovering gold, silver and iron from waste slag by co-roasting pyrite. DETAILED DESCRIPTION

[0033] The principles and features of the present invention are described below in conjunction with examples. The examples are only used to explain the present invention and are not used to limit the scope of the present invention.

[0034] Embodiment 1:

[0035] like Figure 1 As shown, a method for comprehensively recovering gold, silver and iron by co-roasting pyrite to treat gold extraction waste residue comprises the following steps:

[0036] The waste slag from cyanide gold extraction of a certain enterprise mainly contains 2g / t gold, 38g / t silver, 32wt% iron and 28wt% water. The sodium cyanide content in the detected water is 0.20wt%.

[0037] 1) Fine grinding and gold extraction treatment: a low-gold pyrite containing 1g / t gold and the above-mentioned cyanide gold extraction waste residue are ground and mixed evenly in a ball mill according to a mass ratio of 1:1, and 5wt% of soda ash is added at the same time to ensure that the grinding fineness of -400 mesh reaches 98%. After grinding, water is used for slurry adjustment to adjust the slurry concentration to 30% by mass, and the stirring time is ensured to be 6 hours. Carbon leaching is performed, that is, activated carbon with a particle size of +20 mesh 98% is added and stirred for 4 hours; then the gold-loaded activated carbon on the sieve and the mixed slurry under the sieve are obtained by screening, and the mixed slurry is dehydrated to obtain a sulfur-containing ore powder with a moisture content of 8%, a gold content of 1g / t, a silver content of 30g / t, a sulfur content of 25%, and an iron content of 36%.

[0038] 2) Low-temperature reduction roasting: The sulfur-containing ore powder obtained in step 1) is fed into a secondary fluidized bed roasting furnace, and a reducing roasting atmosphere is maintained. The roasting temperature is controlled at 450° C. The oxygen supply is 91% of the total oxygen required for the complete combustion of the material, and the reducing roasting atmosphere is fully guaranteed. The reaction time is 50 minutes. The flue gas containing sulfur dioxide, sulfur trioxide, fine-grained mineral dust, etc. produced by the roasting is purified, converted, absorbed, and other processes through traditional acid production processes to produce industrial sulfuric acid products. Pollutants such as cyanide, arsenic, and heavy metals are removed by simultaneous roasting. At the same time, low-temperature reducing roasted sand containing 1.5 g / t of gold, 40 g / t of silver, and 40% of iron is produced.

[0039] 3) flotation enrichment of gold, silver and copper: the low-temperature reduced roasted sand produced in step 2) is wet-ground, the grinding fineness is -400 mesh 90%, the amount of sodium sulfide added is 500g / t, the lead nitrate is 200g / t, and the stirring is carried out for 20min; the amount of collector butyl xanthate is 800g / t, 25# black medicine is 300g / t, the process flow of one roughing selection, two scavenging selections and four concentrating selections is carried out, the total flotation time is 30 minutes, and the flotation enrichment concentrate containing 15g / t of gold, 300g / t of silver and 3% of copper and the flotation tailings containing 0.30g / t of gold, 3g / t of silver and 43% of iron are produced, and the moisture content is 8% after dehydration and filtration.

[0040] 4) High-temperature reduction roasting and magnetic iron separation: 8wt% of calcium oxide and 8wt% of coal gangue are added to the flotation tailings after dehydration and pressure filtration, mixed by a mixer, and pellets with a diameter of 5mm are obtained by a disc ball making machine, and reduction roasting is carried out in a rotary kiln. The oxygen supply is 85% of the total oxygen required for the complete combustion of the materials, the roasting temperature is 950°C, and the roasting time is 60min. After roasting, the pellets are quenched with water, rapidly cooled, and finely ground to -200 mesh 85% by a ball mill. The ore concentration is adjusted to a mass percentage of 25% by water and transported to a magnetic separator. The slurry flow rate is controlled at 20t / h and the magnetic field strength is 100mT. After magnetic separation, an iron concentrate containing 70wt% of iron and 0.3wt% of sulfur is produced, and the iron recovery rate is 90%. The magnetic separation tailings are identified as general solid waste containing 70wt% of silicon dioxide, which is used as raw materials for building materials production, realizing the clean treatment of pyrite and gold extraction waste slag and the comprehensive recycling of gold, silver and iron resources.

[0041] Embodiment 2:

[0042] The cyanide tailings of a certain enterprise mainly contain 2.2g / t gold, 40g / t silver, 35% iron, 30% water, and the sodium cyanide content in the detected water is 0.25%.

[0043] 1) Fine grinding and gold extraction treatment: The low-gold pyrite containing 2g / t of gold and the above-mentioned cyanide gold extraction waste residue are ground and mixed evenly in a ball mill at a mass ratio of 1:1, and 7.5% of soda ash is added at the same time to ensure that the grinding fineness of -400 mesh reaches 99%. After grinding, water is used for slurry adjustment to adjust the slurry concentration to 33% by mass, and the stirring time is ensured to be 8 hours. Carbon leaching is performed, that is, activated carbon with a particle size of +20 mesh 98% is added, and stirred for 5 hours. The gold-loaded activated carbon on the sieve and the mixed slurry under the sieve are obtained by screening. The mixed slurry is dehydrated to obtain sulfur-containing ore powder with a moisture content of 10%, a gold content of 1.5g / t, a silver content of 35g / t, a sulfur content of 27%, and an iron content of 40%.

[0044] 2) Low-temperature reduction roasting: The sulfur-containing ore powder obtained in step 1) is fed into a secondary fluidized bed roasting furnace, and a reducing roasting atmosphere is maintained. The roasting temperature is controlled at 500° C. The oxygen supply is 93% of the total oxygen required for the complete combustion of the material, and the reducing roasting atmosphere is fully guaranteed. The reaction time is 60 minutes. The flue gas containing sulfur dioxide, sulfur trioxide, fine-grained mineral dust, etc. produced by the roasting is purified, converted, absorbed, and other processes through traditional acid production processes to produce industrial sulfuric acid products. Pollutants such as cyanide, arsenic, and heavy metals are removed by simultaneous roasting. At the same time, low-temperature reducing roasted sand containing 2.0 g / t of gold, 45 g / t of silver, and 45% of iron is produced.

[0045] 3) flotation enrichment of gold, silver and copper: the low-temperature reduced roasted sand produced in step 2) is wet-milled, the grinding fineness is -400 mesh 93%, the amount of sodium sulfide added is 750g / t, the amount of lead nitrate added is 250g / t, stirring is 30min, the amount of collector butyl xanthate is 1200g / t, 25# black medicine is 400g / t, the process flow of one roughing selection, two scavenging selection and four concentrating selection is carried out, the total flotation time is 45 minutes, and the flotation enrichment concentrate containing 20g / t of gold, 400g / t of silver and 3-6% of copper and the flotation tailings containing 0.40g / t of gold, 4g / t of silver and 48% of iron are produced, and the moisture content is 9% after dehydration and filtration;

[0046] 4) High-temperature reduction roasting and magnetic iron separation: 10% calcium oxide and 10% coal gangue are added to the flotation tailings after dehydration and pressure filtration, mixed by a mixer, and pellets with a diameter of 6 mm are obtained by a disc ball making machine, and reduction roasting is carried out in a rotary kiln. The oxygen supply is 90% of the total oxygen required for the complete combustion of the materials, the roasting temperature is 1000°C, and the roasting time is 75 minutes. After roasting, the pellets are quenched with water and rapidly cooled, and finely ground by a ball mill to 90% of 200 mesh. The ore concentrate is adjusted to 30% by mass with water and transported to a magnetic separator. The slurry flow rate is controlled to 25 t / h and the magnetic field strength is 110 mT. After magnetic separation, an iron concentrate containing 75% iron and 0.4% sulfur is produced, and the iron recovery rate is 92.5%. The identification result of the magnetic separation tailings is a general solid waste containing 65% silicon dioxide, which is used as a raw material for building materials production, realizing the clean treatment of pyrite and gold extraction waste slag and the comprehensive recycling of gold, silver and iron resources.

[0047] Embodiment 3:

[0048] The cyanide tailings of a certain enterprise mainly contain 3g / t gold, 45g / t silver, 38% iron and 28% water. The sodium cyanide content in the detected water is 0.26%.

[0049] 1) Fine grinding and gold extraction treatment: low-gold pyrite containing 3g / t gold and gold extraction waste slag containing 3g / t gold are ground and mixed evenly in a ball mill in a mass ratio of 1:1, and 10% of soda ash is added to ensure that the grinding fineness -400 mesh reaches 100%. After grinding, water is used for slurry adjustment to adjust the slurry concentration to 35% by mass, and the stirring time is ensured to be 10 hours. Carbon leaching is performed, that is, activated carbon with a particle size of +20 mesh 98% is added, and stirred for 6 hours. The gold-loaded activated carbon on the sieve and the mixed slurry under the sieve are obtained by screening. The mixed slurry is dehydrated to obtain sulfur-containing ore powder with a moisture content of 12%, a gold content of 2g / t, a silver content of 40g / t, a sulfur content of 30%, and an iron content of 44%.

[0050] 2) Low-temperature reduction roasting: The sulfur-containing ore powder obtained in step 1) is fed into a secondary fluidized bed roasting furnace, and a reducing roasting atmosphere is maintained. The roasting temperature is controlled at 550° C. The oxygen supply is 95% of the total oxygen required for the complete combustion of the material, and the reducing roasting atmosphere is fully guaranteed. The reaction time is 70 minutes. The flue gas containing sulfur dioxide, sulfur trioxide, fine-grained mineral dust, etc. produced by the roasting is purified, converted, absorbed, and other processes through traditional acid production processes to produce industrial sulfuric acid products. Pollutants such as cyanide, arsenic, and heavy metals are removed by simultaneous roasting. At the same time, low-temperature reducing roasted sand containing 2.5 g / t of gold, 50 g / t of silver, and 50% of iron is produced.

[0051] 3) flotation enrichment of gold, silver and copper: the low-temperature reduced roasted sand produced in step 2) is wet ground, the grinding fineness is -400 mesh 95%, the amount of sodium sulfide added is 1000g / t, the lead nitrate is 300g / t, the stirring is 40min, the amount of collector butyl xanthate is 1600g / t, the amount of 25# black medicine is 500g / t, the process flow of one roughing selection, two scavenging selections and four concentrating selections is adopted, the total flotation time is 60 minutes, and the flotation enrichment concentrate containing 25g / t of gold, 500g / t of silver and 6% of copper and the flotation tailings containing 0.50g / t of gold, 5g / t of silver and 53% of iron are produced. After dehydration and filtration, the moisture content is 10.

[0052] 4) High-temperature reduction roasting and magnetic iron separation: 12% calcium oxide and 12% coal gangue are added to the flotation tailings after dehydration and pressure filtration, mixed by a mixer, and pellets with a diameter of 7 mm are obtained by a disc ball making machine, and reduction roasting is carried out in a rotary kiln. The oxygen supply is 95% of the total oxygen required for the complete combustion of the materials, the roasting temperature is 1050°C, and the roasting time is 90 min. After roasting, the pellets are quenched with water and rapidly cooled, and finely ground by a ball mill to 95% of 200 mesh. The ore concentration is adjusted to 35% by mass with water and transported to a magnetic separator. The slurry flow rate is controlled at 30 t / h and the magnetic field strength is 120 mT. After magnetic separation, an iron concentrate containing 80% iron and 0.5% sulfur is produced, and the iron recovery rate is 95%. The identification result of the magnetic separation tailings is a general solid waste containing 70% silicon dioxide, which is used as a raw material for building materials production, realizing the clean treatment of pyrite and gold extraction waste slag and the comprehensive recycling of gold, silver and iron resources.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for comprehensively recovering gold, silver and iron from waste slag by co-roasting pyrite, characterized in that: The steps include: 1) Fine grinding and gold extraction treatment: Grind and mix the gold-containing low-gold pyrite and gold-containing gold extraction waste slag evenly, and add soda ash at the same time; adjust the slurry concentration to 30-35wt% after grinding, and stir for 6-10h; then add activated carbon and stir for 4-6h; then sieve to obtain the gold-loaded activated carbon on the sieve and the mixed slurry under the sieve; dehydrate the mixed slurry under the sieve to obtain sulfur-containing ore powder; 2) Low-temperature reduction roasting: the sulfur-containing ore powder obtained in step 1) is fed into a secondary fluidized bed roasting furnace, and a reducing roasting atmosphere is maintained, and the roasting produces flue gas and low-temperature reducing roasted sand; the roasting temperature is 450-550°C; 3) Flotation enrichment of gold, silver and copper: The low-temperature reduced roasted sand produced in step 2) is wet-ground, sodium sulfide and lead nitrate are added and stirred for 20-40 minutes, and then butyl xanthate and 25# black medicine are added as collectors. The process is followed by one roughing, two scavenging and four concentrating steps, and flotation produces flotation enriched concentrate and flotation tailings; 4) High-temperature reduction roasting for magnetic iron separation: After dehydration and filter pressing of the flotation tailings produced in step 3), calcium oxide and coal gangue are added, mixed, pelletized, and reduced and roasted in a rotary kiln. The roasting temperature is 950-1050°C. After roasting, the pellets are quenched with water, rapidly cooled, ball milled, and slurried, and then transported to a magnetic separator to produce iron concentrate and magnetic tailings through magnetic separation.

2. The method for comprehensive recovery of gold, silver and iron from pyrite coordinated roasting treatment of gold extraction waste slag according to claim 1, characterized in that: In the step 1), the amount of soda ash added is 5-10wt%; the grinding fineness after grinding is -400 mesh 98-100%; and the particle size of the activated carbon is +20 mesh 98%.

3. The method for comprehensive recovery of gold, silver and iron from pyrite coordinated roasting treatment of gold extraction waste slag according to claim 1, characterized in that: In the step 2), the oxygen supply for roasting is 91-95% of the total oxygen required for the complete combustion of the materials; and the roasting time is 50-70 minutes.

4. The method for comprehensive recovery of gold, silver and iron from pyrite coordinated roasting treatment of gold extraction waste slag according to claim 2, characterized in that: In the step 3), the grinding fineness after wet grinding is -400 mesh 90-95%.

5. The method for comprehensive recovery of gold, silver and iron from pyrite coordinated roasting treatment of gold extraction waste slag according to claim 2, characterized in that: In the step 3), the amount of sodium sulfide added is 500-1000 g / t, the amount of lead nitrate added is 200-300 g / t; the amount of collector butyl xanthate added is 800-1600 g / t, and the amount of 25# black medicine added is 300-500 g / t.

6. The method for comprehensive recovery of gold, silver and iron from pyrite coordinated roasting treatment of gold extraction waste slag according to claim 5, characterized in that: In the step 3), the total flotation time is 30 to 60 minutes.

7. The method for comprehensive recovery of gold, silver and iron from pyrite coordinated roasting treatment of gold extraction waste slag according to claim 1, characterized in that: In the step 4), the amount of calcium oxide added is 8-12wt%, and the amount of coal gangue added is 8-12wt%.

8. The method for comprehensive recovery of gold, silver and iron from pyrite coordinated roasting treatment of gold extraction waste slag according to claim 7, characterized in that: In the step 4), a disc ball making machine is used to make pellets, the diameter of the pellets is 5-7 mm; the fineness after ball milling -200 mesh is 85-95%; the concentration of the slurry after slurry adjustment is 20-30wt%.

9. The method for comprehensive recovery of gold, silver and iron from pyrite coordinated roasting treatment of gold extraction waste slag according to claim 7, characterized in that: The oxygen supply in the rotary kiln is 85-95% of the total oxygen required for the complete combustion of the materials, and the roasting time is 60-90 minutes.

10. The method for comprehensive recovery of gold, silver and iron from waste slag by coordinated roasting of pyrite according to claim 7, characterized in that: In the step 4), the slurry flow rate transported to the magnetic separator is 20-30 t / h, and the magnetic field strength is 100-120 mT.

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