Efficient dressing and smelting method for refractory high-sulfur high-arsenic carbon-containing low-grade gold ore

Abstract

The invention discloses an efficient dressing and smelting method for refractory high-sulfur high-arsenic carbon-containing low-grade gold ore. Comprising the steps of crushing-screening operation, dense medium mineral separation and waste throwing of products with the particle size being-15 + 0.5 mm, combined ore grinding of dense medium concentrate and products with the particle size being-0.5 mm, Nelson reselection, Nelson tailing magnetic separation operation, magnetic separation tailing sulfur and arsenic asynchronous flotation separation operation, magnetic separation concentration concentrate and low-arsenic gold-containing sulfur concentrate roasting-carbon leaching operation. And carrying out superfine grinding-carbon leaching operation on the high-arsenic gold-containing sulfur concentrate. According to the method, gold, iron and sulfur metal resources can be comprehensively recycled, and high-efficiency recycling of the refractory high-arsenic high-sulfur carbon-containing low-grade gold ore is achieved.

Description

Technical Field

[0001] This invention relates to the field of beneficiation and metallurgy technology for refractory low-grade gold ores, and specifically to an efficient beneficiation and metallurgy method for refractory high-sulfur, high-arsenic, and carbon-containing low-grade gold ores. Background Technology

[0002] Of the proven gold reserves in China, refractory gold mines account for over 30%. Among them, high-sulfur, high-arsenic, carbonaceous gold mines are typical examples of refractory gold, and their recovery difficulty is far greater than that of ordinary gold mines. In high-sulfur, high-arsenic gold mines, the arsenic is mainly in the form of arsenopyrite and pyrite. Gold minerals are often encased in arsenopyrite or pyrite at the micron or even nanometer scale. Conventional fine or ultrafine grinding processes cannot break the inclusions, preventing the gold from contacting the leaching agent, resulting in low recovery rates. However, commonly used roasting oxidation or pressurized oxidation pretreatment can expose the gold minerals, followed by carbon leaching or stirred leaching, which can achieve higher gold recovery rates. However, the pretreatment process generates a large amount of arsenic-containing waste gas and acidic wastewater, causing serious pollution to the air, soil, and water sources, which does not comply with current strict environmental protection policies. High-carbon gold mines refer to those containing organic carbon. Due to their strong adsorption properties, they preferentially adsorb dissolved gold-cyanide complexes (i.e., "gold robbery"), reducing the gold recovery rate.

[0003] To maximize the recovery of gold minerals from high-arsenic and high-carbon gold ores, arsenopyrite-bearing gold minerals and pyrite-bearing gold minerals are separated by flotation to obtain high-arsenic gold-bearing sulfur concentrate and low-arsenic gold-bearing sulfur concentrate. The low-arsenic gold concentrate can be pretreated by roasting or hot pressing, achieving a higher gold recovery rate while reducing the environmental impact of arsenic and mitigating the problem of harmless arsenic disposal. Therefore, developing an efficient arsenopyrite depressant to achieve the separation of pyrite and arsenopyrite has become a key factor restricting this technology. Simultaneously, for both high-arsenic and low-arsenic gold-bearing sulfur concentrates, reasonable and feasible gold extraction processes need to be studied, balancing gold recovery rate and reducing the environmental impact of arsenic. Given the large reserves of this low-grade gold ore, developing low-cost beneficiation pretreatment methods to reduce crushing and beneficiation process costs is also crucial for the development value of this gold ore. While photoelectric pre-selection and polishing methods are widely used in tungsten-tin, iron, manganese, and chromium ores, their application in gold mines is relatively limited. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention aims to provide an efficient beneficiation and smelting method for refractory, high-sulfur, high-arsenic, carbon-containing, low-grade gold ores. This method can comprehensively recover gold, iron, and sulfur metal resources, achieving efficient recycling of refractory, high-arsenic, high-sulfur, carbon-containing, low-grade gold ores.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A highly efficient beneficiation method for refractory, high-sulfur, high-arsenic, carbon-containing, low-grade gold ores includes the following steps: S1. Crushing and screening operation: The raw ore is crushed, and the crushed product is screened at 15mm and 0.5mm. The product over the +15mm screen is returned to crushing to obtain two particle sizes: -15 +0.5mm and -0.5mm. S2, Heavy media separation waste disposal: The -15+0.5mm particle size product obtained in step S1 is fed into a heavy media hydrocyclone containing heavy media for heavy media separation to obtain heavy media concentrate and heavy media tailings. The heavy media tailings enter the flotation tailings dam. S3. Grinding-Nelson gravity separation: The heavy media concentrate obtained in step S2 and the -0.5mm particle size product obtained in step S1 are combined and fed into a grinding mill for grinding. The fineness of the grinding product is -0.075mm with a content of 60-70%. The resulting grinding product is fed into a Nelson concentrator for gravity separation. The gravity separation yields Nelson concentrate and Nelson tailings. S4. Nelson tailings magnetic separation operation: The Nelson tailings obtained in step S3 are fed into a wet weak magnetic separator for magnetic roughing and magnetic cleaning in sequence. The magnetic roughing produces magnetic roughing concentrate and magnetic roughing tailings. The magnetic roughing concentrate enters the magnetic cleaning process to obtain magnetic cleaning concentrate and magnetic cleaning tailings. The magnetic roughing tailings and magnetic cleaning tailings are combined into magnetic tailings. S5. Asynchronous sulfur-arsenic flotation separation operation: The magnetic separation tailings obtained in step S4 are fed into a flotation machine for sulfur flotation to obtain low-arsenic gold-bearing sulfur concentrate and sulfur tailings; then the sulfur tailings are further subjected to arsenic flotation to obtain high-arsenic gold-bearing sulfur concentrate and flotation tailings, and the flotation tailings are sent into the flotation tailings dam. S6. Roasting-Carbon Leaching Operation: The magnetically separated concentrate obtained in step S4 and the low-arsenic gold-containing sulfur concentrate obtained in step S5 are combined and fed into the roasting furnace. Sulfuric acid is produced by roasting. The roasting residue is subjected to carbon leaching. Activated carbon is added during the carbon leaching process. Then the carbon leaching tailings are screened to obtain gold-loaded carbon and carbon leaching tailings slurry. S7. Ultrafine grinding-carbon leaching operation: The high-arsenic gold-containing sulfur concentrate obtained in step S5 is fed into an arsine mill and ground to P80@10μm through ultrafine grinding. After adjusting the ultrafine grinding product to a slurry with a mass concentration of 42%, carbon leaching is carried out. Activated carbon is added during the carbon leaching process. The obtained carbon leaching tailings are screened to obtain gold-loaded carbon and carbon leaching tailings slurry. S8. The gold-loaded carbon obtained in steps S6 and S7 is subjected to desorption and electrolysis to obtain crude gold and activated carbon. The activated carbon is returned to the carbon leaching process for recycling.

[0006] Further, in step S2, the heavy medium is ferrosilicon powder, and its density is 2.7 g / cm³. 3 .

[0007] Furthermore, in step S3, the gravity multiplier is reselected to 60G.

[0008] Furthermore, in step S4, the magnetic field strengths for the roughing and cleaning magnetic separation are 230 mT and 140 mT, respectively.

[0009] Further, in step S5, the sulfur flotation process includes a secondary sulfur roughing and a secondary sulfur cleaning. Based on the weight of each ton of dry raw ore, the sulfur roughing stage adds 4500-5500 g / t of arsenic inhibitor, 60-80 g / t of sulfur collector ethyl xanthate or butyl xanthate, and 20-30 g / t of No. 2 oil. The sulfur roughing stage adds 20-30 g / t of ethyl xanthate or butyl xanthate and 10 g / t of No. 2 oil. No reagents are added in the sulfur cleaning stage. The pulp pH in the sulfur roughing stage is 8.8-9.4. The arsenic flotation process includes a primary arsenic roughing, a secondary arsenic scavenging, and a secondary arsenic cleaning. Based on the weight of each ton of dry raw ore, the arsenic roughing stage adds 150-180 g / t of copper sulfate, 10 g / t of No. 2 oil, 70 g / t of butyl xanthate collector, and 30 g / t of butylammonium black powder. The arsenic scavenging stage adds 30 g / t of butyl xanthate. Add 10g / t of butyl xanthate and 10g / t of No. 2 oil to the second arsenic scavenging process. Add 30g / t of butyl xanthate and 10g / t of butyl xanthate to the second arsenic scavenging process. No reagents are added to the arsenic beneficiation process.

[0010] Furthermore, in step S5, the arsenic inhibitor comprises sodium carbonate, zinc sulfate, and sodium sulfite, with a mass ratio of 9:10:5.

[0011] Furthermore, in step S6, the calcination temperature is 650℃-700℃, and the calcination time is 1 hour.

[0012] Furthermore, the carbon leaching process in step S6 maintains a carbon density of 40 g / L, and the carbon leaching process in step S7 maintains a carbon density of 60 g / L.

[0013] Furthermore, lime is added to adjust the slurry in both steps S6 and S7 of the carbon leaching operation. The amount of lime used is 4-6 kg / t based on the dry weight of each ton of ore to be leached. The pH of the slurry after adjustment is 10.8-11.5, and the sodium cyanide concentration is controlled at 1‰.

[0014] Further, the carbon leaching tailings slurry obtained in step S6 is sent to a thickening and filtration system for dewatering to obtain iron concentrate with Fe grade >60%; the carbon leaching tailings slurry obtained in step S7 is sent to a thickener for thickening and dewatering, and the resulting return water is returned to the carbon leaching operation in step S7. The resulting underflow mass concentration is 40-50%, and it is finally sent to the carbon leaching tailings pond.

[0015] The beneficial effects of this invention are as follows: (1) This invention creatively proposes a heavy media pre-selection waste disposal technology for low-grade gold ore. It utilizes the strong correlation between gold and sulfides and the coarse particle size of sulfides, which can be enriched by heavy media beneficiation waste disposal. Gold can be enriched by 4-5 times, with an operation recovery rate of >90% and a comprehensive waste disposal rate of about 70%. The ore is crushed to -15mm, which can significantly reduce the process cost of subsequent grinding and beneficiation. At the same time, about 70% of organic carbon can be disposed of, reducing carbon stealing of gold in subsequent leaching processes, reducing the carbon stealing index, and reducing the impact of organic carbon on carbon leaching gold stealing. (2) The present invention uses Nelson gravity separation of granular gold, which has the advantage of high enrichment ratio, and obtains high-grade heavy sand, which can improve the gold grade in heavy sand, increase the ratio of gold grade to arsenic grade, and increase the sales value of gold; both granular gold minerals and arsenopyrite have a large specific gravity, and arsenopyrite is easily enriched in gravity separation concentrate. By further reducing the yield and increasing the enrichment ratio, Nelson concentrate (heavy sand) with Au grade >500g / t can be obtained; (3) This invention proposes a wet weak magnetic separation of pyrrhotite and magnetite in gravity separation tailings. Due to the easy oxidation of pyrrhotite, the sodium cyanide consumption in subsequent carbon leaching is extremely high. Based on this, by utilizing its strong magnetic properties, a wet weak magnetic separator is used to magnetically separate pyrrhotite and magnetite, which can significantly reduce the subsequent sodium cyanide consumption and reduce the cost of beneficiation and metallurgy. (4) This invention proposes a highly efficient arsenopyrite inhibitor, which can effectively inhibit the flotation of arsenopyrite, solve the difficulty of separating pyrite and arsenopyrite, achieve efficient flotation separation of sulfur and arsenic, and obtain low-arsenic gold-bearing sulfur concentrate (As<1%) and high-arsenic gold-bearing sulfur concentrate (As>10%). The obtained low-arsenic gold-bearing sulfur concentrate can achieve a high gold recovery rate after roasting, oxidation and carbon leaching, while the impact of arsenic on the environment is relatively small. (5) This invention proposes a roasting oxidation-carbon leaching process for low-arsenic gold-sulfur concentrate and magnetic separation concentrate. The roasting oxidation pretreatment fully exposes the gold minerals that are encapsulated before carbon leaching, which can achieve a high gold leaching rate. The sulfuric acid produced by roasting can be sold for external processing, and the roasting oxidation slag can be sold as iron concentrate. This comprehensively recovers gold, iron and sulfur resources. (6) In this invention, an ultrafine grinding-carbon leaching process is proposed for high arsenic gold-sulfur concentrate. Due to its low gold grade and low gold-arsenic ratio, the oxidation pretreatment process for high arsenic gold-sulfur concentrate has a high gold recovery rate, but the harmless disposal of arsenic is difficult and the production cost is high. The ultrafine grinding-carbon leaching method is relatively stable, avoids the problem of harmless disposal of arsenic, minimizes the harm of arsenic, and can realize large-scale production. (7) This invention provides a low-cost, high-efficiency, highly efficient, targeted, and environmentally friendly method for the beneficiation and smelting of low-grade gold ore, which can comprehensively recover gold, iron, and sulfur resources, and provides technical reference for the recovery of this type of difficult-to-process high-sulfur, high-arsenic, and carbon-containing gold ore resources. Attached Figure Description

[0016] Figure 1 This is a flowchart of a method according to an embodiment of the present invention. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0018] A large, difficult-to-process, high-sulfur, high-arsenic, low-carbon gold mine in Liaoning Province. The raw ore contains 0.48 g / t Au, 4.2% S, 0.40% As, and S... 2- The ore contains 3.86% gold and 0.023% organic carbon. The main gold minerals are native gold and silver-gold ore, the main sulfides are pyrite and pyrrhotite, the main arsenic-bearing mineral is arsenopyrite, and the main gangue minerals are quartz and muscovite, with minor amounts of chlorite and kaolinite. The raw ore has a low gold grade, high sulfur and arsenic content, and a low gold-to-sulfur ratio, resulting in a low gold grade in the flotation concentrate. Furthermore, the high arsenic content in the concentrate makes it difficult to sell, hindering the development of this low-grade gold mine.

[0019] This embodiment provides an efficient beneficiation method for refractory, high-sulfur, high-arsenic, carbon-containing, low-grade gold ores. Processing these ores enables low-cost, high-efficiency development and reduces environmental impact. The specific process is as follows: Figure 1 As shown, the main steps include the following: S1. Crushing-screening operation: The raw ore is crushed, and the crushed product is screened at 15mm and 0.5mm. The product over the +15mm screen is returned to crushing to obtain two particle size products: -15 +0.5mm and -0.5mm. The yield of the -0.5mm particle size product is 7%.

[0020] S2. Heavy Media Concentration Waste Disposal: The -15 +0.5mm particle size product obtained in step S1 is fed into a heavy media hydrocyclone for heavy media concentration. Heavy media is added to the hydrocyclone to obtain heavy media concentrate and heavy media tailings. The heavy media tailings are then sent to the flotation tailings pond. The heavy media used has a density of 2.7 g / cm³. 3 The heavy medium waste rate of the ferrosilicon powder was 69.84%.

[0021] S3. Grinding-Nelson Gravity Separation: The heavy media concentrate obtained in step S2 and the -0.5mm particle size product obtained in step S1 are fed into a grinding mill for grinding. The fineness of the grinding product is -0.075mm with a content of 68%. The resulting grinding product is fed into a Nelson concentrator for gravity separation. The gravity separation ratio is 60G. The gravity separation yields Nelson concentrate (heavy sand) and Nelson tailings. The heavy sand contains Au > 500g / t. S4. Nelson tailings magnetic separation operation: The Nelson tailings obtained in step S3 are fed into a wet weak magnetic separator for magnetic roughing and magnetic cleaning in sequence. Magnetic roughing produces magnetic roughing concentrate and magnetic roughing tailings. The magnetic roughing concentrate enters the magnetic cleaning process to produce magnetic cleaning concentrate and magnetic cleaning tailings. The magnetic roughing tailings and magnetic cleaning tailings are combined into magnetic tailings. The magnetic field strengths for magnetic roughing and magnetic cleaning are 230mT and 140mT, respectively.

[0022] S5. Magnetic tailings sulfur-arsenic asynchronous flotation separation operation: The magnetic tailings obtained in step S4 are fed into a flotation machine for sulfur flotation to obtain low-arsenic gold-bearing sulfur concentrate (containing As<1%) and sulfur tailings; the sulfur tailings are further subjected to arsenic flotation to obtain high-arsenic gold-bearing sulfur concentrate (containing As>10%) and flotation tailings, and the flotation tailings are sent into the flotation tailings dam.

[0023] S6. Roasting-Carbon Leaching Operation: The magnetically separated concentrate obtained in step S4 and the low-arsenic gold-bearing sulfur concentrate obtained in step S5 are fed into a roasting furnace. The temperature is adjusted to 650℃ and roasted for 1 hour. Sulfuric acid is produced during roasting. The roasting residue is then subjected to carbon leaching, with lime added to adjust the slurry. The lime dosage is 6 kg / t based on the dry weight of each ton of ore added for leaching. The slurry pH is 11.2, and the sodium cyanide concentration is controlled at 1‰. Activated carbon is added during the carbon leaching process to maintain a carbon density of 40 g / L. The carbon leaching tailings are screened to separate gold-loaded carbon and carbon leaching tailings slurry. The gold-loaded carbon undergoes desorption and electrolysis to obtain crude gold (gold mud) and activated carbon. The activated carbon is returned to the carbon leaching operation for recycling.

[0024] S7. Ultrafine Grinding—Carbon Leaching Operation: The high-arsenic gold-bearing sulfur concentrate obtained in step S5 is fed into an arsine mill for ultrafine grinding to P80@10μm. The slurry is adjusted to a mass concentration of 42% for carbon leaching. Lime is added to the slurry during carbon leaching, with a lime dosage of 4 kg / t based on the dry weight of each ton of ore being leached. The slurry pH is 10.8, and the sodium cyanide concentration is controlled at 1‰. Activated carbon is added during carbon leaching to maintain a carbon density of 60 g / L. The resulting carbon leaching tailings are screened to separate gold-loaded carbon and carbon leaching tailings slurry. The gold-loaded carbon undergoes desorption and electrolysis to obtain crude gold (gold mud) and activated carbon. The activated carbon is returned to the carbon leaching operation for recycling.

[0025] In this embodiment, the sulfur flotation in step S5 includes secondary sulfur roughing and secondary sulfur cleaning. Based on the weight of each ton of dry raw ore, 4900 g / t of arsenic inhibitor, 72 g / t of sulfur collector ethyl xanthate, and 26 g / t of No. 2 oil are added to sulfur roughing one; 28 g / t of ethyl xanthate and 10 g / t of No. 2 oil are added to sulfur roughing two; no reagents are added to sulfur cleaning. The pH of the pulp in sulfur roughing one is 9.1. The arsenic inhibitor is a mixture of sodium carbonate, zinc sulfate, and sodium sulfite in a mass ratio of 9:10:5.

[0026] In this embodiment, the arsenic flotation process described in step S5 includes primary arsenic roughing, secondary arsenic scavenging, and secondary arsenic cleaning. Based on the weight of each ton of dry raw ore, the arsenic roughing process adds 170 g / t of copper sulfate, 70 + 30 g / t of butyl xanthate + butyl ammonium black reagent, and 10 g / t of No. 2 oil. The arsenic scavenging process adds 30 + 10 g / t of butyl xanthate + butyl ammonium black reagent and 10 g / t of No. 2 oil. The arsenic scavenging process adds 30 + 10 g / t of butyl xanthate + butyl ammonium black reagent. No reagents are added for the arsenic cleaning process.

[0027] In this embodiment, the carbon leaching tailings slurry obtained in step S6 is dewatered by a thickening and filtration system to obtain iron concentrate with Fe grade >60%; the carbon leaching tailings slurry obtained in step S7 is sent to a thickener for thickening and dewatering, and the recycled water is returned to the carbon leaching operation in step S7. The underflow mass concentration of the thickener is 48%, and it is finally sent to the carbon leaching tailings pond.

[0028] The process parameters of this embodiment are shown in Tables 1 and 2.

[0029] Table 1

[0030] Table 2

[0031] * indicates the unit is g / t As shown in Table 1, the total recovery rate of the method in this embodiment (comprehensive gold recovery rate of gravity separation + flotation) is 84.7%; the total gold recovery rate of the entire beneficiation and smelting process (comprehensive gold recovery rate of gravity separation + magnetic separation + flotation + leaching) is 73.6%. The method in this embodiment is low in cost, has little environmental impact, and produces good comprehensive gold indicators. It is operable and can turn large, difficult-to-process, low-grade gold mines into valuable resources.

[0032] For those skilled in the art, various corresponding changes and modifications can be made based on the above technical solutions and concepts, and all such changes and modifications should be included within the protection scope of the claims of this invention.

Claims

1. A high-efficiency beneficiation and smelting method of a refractory high-sulfur high-arsenic carbon-containing low-grade gold ore, characterized in that, The method comprises the following steps: S1, crushing-screening operation: crushing the raw ore, screening the crushing product into 15 mm and 0.5 mm, returning the +15 mm screen product to crushing, and obtaining -15+0.5 mm and -0.5 mm products; S2, heavy medium beneficiation and waste discarding: feeding the -15+0.5 mm product obtained in step S1 into a heavy medium cyclone with heavy medium for heavy medium beneficiation, obtaining heavy medium concentrate and heavy medium tailings, and feeding the heavy medium tailings into a flotation tailings pond; S3, grinding-Nelson gravity separation: combining the heavy medium concentrate obtained in step S2 and the -0.5 mm product obtained in step S1 and feeding into a mill for grinding, the grinding product having a fineness of -0.075 mm content of 60-70%; feeding the obtained grinding product into a Nelson concentrator for gravity separation operation, and obtaining Nelson concentrate and Nelson tailings by gravity separation; S4, magnetic separation operation of Nelson tailings: feeding the Nelson tailings obtained in step S3 into a wet low-intensity magnetic separator in turn for rough magnetic separation and fine magnetic separation, obtaining rough magnetic separation concentrate and rough magnetic separation tailings by rough magnetic separation, feeding the rough magnetic separation concentrate into fine magnetic separation, obtaining fine magnetic separation concentrate and fine magnetic separation tailings, and combining the rough magnetic separation tailings and the fine magnetic separation tailings into magnetic separation tailings; S5, sulfur-arsenic asynchronous flotation separation operation: feeding the magnetic separation tailings obtained in step S4 into a flotation machine to perform sulfur flotation first, obtaining low-arsenic gold-containing sulfur concentrate and sulfur tailings; and then further performing arsenic flotation on the sulfur tailings to obtain high-arsenic gold-containing sulfur concentrate and flotation tailings, and feeding the flotation tailings into a flotation tailings pond; S6, roasting-carbon-in-leach operation: combining the fine magnetic separation concentrate obtained in step S4 and the low-arsenic gold-containing sulfur concentrate obtained in step S5 and feeding into a roasting furnace, roasting to produce sulfuric acid, performing carbon-in-leach operation on the roasting slag, adding activated carbon in the carbon-in-leach process, and then screening the obtained carbon-in-leach tailings to obtain gold-loaded carbon and carbon-in-leach tailings slurry; S7, ultra-fine grinding-carbon-in-leach operation: feeding the high-arsenic gold-containing sulfur concentrate obtained in step S5 into a Aimesha mill, grinding the high-arsenic gold-containing sulfur concentrate to P80@10μm by ultra-fine grinding, adjusting the ultra-fine grinding product to a mass concentration of 42% to perform carbon-in-leach operation, adding activated carbon in the carbon-in-leach process, and screening the obtained carbon-in-leach tailings to obtain gold-loaded carbon and carbon-in-leach tailings slurry; S8, desorption and electrolysis operation on the gold-loaded carbon obtained in steps S6 and S7 to obtain crude gold and activated carbon, and returning the activated carbon to the carbon-in-leach operation for recycling.

2. The method of claim 1, wherein, In step S2, the heavy medium is ferrosilicon powder, and the heavy medium density is 2.7 g / cm 3 .

3. The method of claim 1, wherein, In step S3, the gravity multiple of gravity separation is 60G.

4. The method of claim 1, wherein, In step S4, the magnetic field strengths of rough magnetic separation and fine magnetic separation are 230mT and 140mT, respectively.

5. The method of claim 1, wherein, In step S5, the process of the selective sulfur flotation includes secondary sulfur roughing and secondary sulfur cleaning, and the sulfur roughing one adds arsenic inhibitor 4500-5500 g / t, sulfur collector ethyl xanthate or butyl xanthate 60-80 g / t, and 2# oil 20-30 g / t per ton of dry ore weight, the sulfur roughing two adds ethyl xanthate or butyl xanthate 20-30 g / t, 2# oil 10 g / t, and the sulfur cleaning does not add reagent; the pulp pH in the sulfur roughing one is 8.8-9.4; the process of the selective arsenic flotation includes primary arsenic roughing, secondary arsenic scavenging and secondary arsenic cleaning, and the arsenic roughing adds copper sulfate 150-180 g / t, 2# oil 10 g / t, and arsenic roughing collector butyl xanthate 70 g / t and ammonium black 30 g / t per ton of dry ore weight, the arsenic scavenging one adds butyl xanthate 30 g / t and ammonium black 10 g / t, and 2# oil 10 g / t, the arsenic scavenging two adds butyl xanthate 30 g / t and ammonium black 10 g / t, and the arsenic cleaning does not add reagent.

6. The method of claim 3, wherein, In step S5, the arsenic inhibitor includes sodium carbonate, zinc sulfate and sodium sulfite, and the mass ratio of sodium carbonate, zinc sulfate and sodium sulfite is 9:10:

5.

7. The method of claim 1, wherein, In step S6, the roasting temperature is 650-700℃, and the roasting time is 1h.

8. The method of claim 1, wherein, In step S6, the carbon-in-pulp operation maintains a carbon density of 40 g / L, and in step S7, the carbon-in-pulp operation maintains a carbon density of 60 g / L.

9. The method of claim 1, wherein, In the carbon-in-pulp operations of step S6 and step S7, lime is added for slurry conditioning, and the amount of lime is 4-6 kg / t per ton of dry ore weight, and the pH of the slurry after conditioning is 10.8-11.5, and the concentration of sodium cyanide is controlled at 1‰.

10. The method of claim 1, wherein, The carbon-in-pulp tailings slurry obtained in step S6 is sent to a thickening pressure filtration system for dewatering to obtain iron concentrate with Fe grade >60%; the carbon-in-pulp tailings slurry obtained in step S7 is sent to a thickener for thickening and dewatering, the returned water is returned to the carbon-in-pulp operation of step S7, and the underflow with mass concentration of 40-50% is finally sent to a carbon-in-pulp tailings pond.

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