Method for improving the quality of pyrite concentrate powder for recovering cyanide tailings

Abstract

This invention proposes a method for improving the quality of pyrite concentrate powder recovered from cyanide tailings, belonging to the field of slag resource utilization technology. The method includes: mixing raw cyanide tailings ore with water to form a cyanide tailings slurry; filtering the slurry through a fixed mesh screen to remove sand and gravel impurities; and conveying the slurry to an activation tank; adding concentrated sulfuric acid to the activation tank to convert cyanide ions into hydrogen cyanide gas, followed by the addition of alkali solution, a collector, and pine oil to obtain a slurry; agitating and aerating the slurry, causing FeS2-containing slurry particles to float to the surface and be scraped off; continuing agitation and aeration to enrich and purify the FeS2-containing slurry particles; further enrichment and purification followed by scraping off the FeS2 slurry particles to recover the FeS2 slurry particles, yielding concentrate and tailings slurries respectively; the concentrate and tailings slurries undergo solid-liquid separation under the action of a slurry pump, followed by pressure filtration; the filtrate is collected and discharged into a workshop circulating water tank for reuse; after unloading, the concentrate and tailings are collected separately. This invention produces high-quality pyrite concentrate powder with an FeS2 content of approximately 90%.

Description

Technical Field

[0001] This invention relates to the field of slag resource utilization technology, specifically to a method for improving the quality of pyrite concentrate powder recovered from cyanide tailings. Background Technology

[0002] Cyanide tailings are industrial waste from gold mining companies. Their main component is FeS2, a major component of pyrite and a relatively scarce mineral resource in my country. For many years, due to the low FeS2 content in cyanide tailings, they have not been properly disposed of and utilized. They have primarily been used in sulfuric acid production plants, resulting in sulfuric acid slag with low iron content. Some of this slag is used as filler in cement production, while some is indiscriminately stockpiled, leading to a waste of iron resources and environmental pollution.

[0003] Currently, the main technology for treating cyanide tailings is flotation, supplemented by autoclaving, chlorination roasting, molten salt roasting, reduction roasting, oxidation, solidification, and the preparation of silicate cement. Flotation is mostly carried out under weakly acidic conditions, under which CN... - The cyanide tailings are unstable and require multiple flotation processes. The autoclaving method, primarily conducted in autoclaves or high-pressure vessels, requires prolonged high-temperature pressure maintenance and necessitates addressing secondary pollution from the autoclaving process. The chlorination roasting method involves mixing chlorinating agents with cyanide tailings and roasting at high temperatures, demanding high equipment corrosion resistance and consuming significant energy. The molten salt roasting method uses molten salt or a molten pool to roast the cyanide tailings, requiring high temperatures and long roasting times. The reduction roasting method uses reducing agents at high temperatures, resulting in long reduction times. The oxidation method uses oxidants such as ozone, hydrogen peroxide, and sodium hypochlorite to oxidize the cyanide tailings, leading to high operating costs. The solidification method uses solidifying agents to solidify the cyanide tailings, but this does not fundamentally solve the potential environmental pollution caused by cyanide tailings. The preparation of silicate cement utilizes cyanide tailings with high aluminum and silicon content to produce ordinary silicate cement. Currently, these methods are either energy-intensive, involve secondary pollution, have incomplete cyanide removal, or have complex processes, resulting in high operating costs. Therefore, there is currently a lack of economical and effective treatment methods for this type of hazardous waste.

[0004] Chinese invention patent CN100361750B discloses a flotation method for removing impurities and purifying sulfur concentrate. The method employs pretreatment and impurity removal flotation, including roughing, scavenging, primary cleaning, and secondary cleaning to obtain the final product. This method improves the utilization rate of waste residue and has good economic benefits, but it also suffers from problems such as complex processes, large equipment investment, and high operating costs. Summary of the Invention

[0005] The purpose of this invention is to propose a method for improving the quality of pyrite concentrate powder recovered from cyanide tailings. The method employs a production process that effectively removes cyanide ions, reducing the hazardous characteristics of the tailings to general solid waste. It also enhances the flotation of pyrite concentrate, increasing the recovery rate and yield, and reducing the amount of solid waste generated. The method involves the organized recovery of waste gas from the activation tank, which undergoes multi-stage alkaline absorption, resulting in low-cost and effective tail gas absorption. Finally, it utilizes a large-scale flotation machine to improve equipment efficiency and reduce energy consumption.

[0006] The technical solution of this invention is implemented as follows: This invention provides a method for improving the quality of pyrite concentrate powder recovered from cyanide tailings, comprising the following steps: (1) The raw material cyanide tailings are mixed with water to make cyanide slag slurry, which is filtered through a fixed screen to remove sand and gravel impurities and then transported to the activation tank. (2) Add concentrated sulfuric acid to the activation tank to destroy the oxide layer on the surface of the fine particles and remove the cyanide ions therein, and turn the cyanide ions into hydrogen cyanide gas, which escapes from the slurry and enters the waste gas absorption treatment device. Add alkaline solution to reduce the unorganized escape of cyanide in the subsequent process. Add a collector to make full contact with the surface of the slurry particles and change the hydrophilic and hydrophobic properties of the particles. Add pine oil to play a bubbling role, and the slurry particles selectively adhere to the surface of the bubbles to obtain the slurry, which overflows to the flotation production device. (3) Under the action of stirring and blowing, the slurry containing FeS2 particles floats to the surface with the air bubbles. Under the action of continued stirring and blowing, the slurry containing FeS2 particles are enriched and purified, and scraped out by the scraper. Under the action of liquid level difference and self-absorption of the flotation machine, FeS2 slurry particles are recovered to obtain concentrate slurry, and the residue is tailings slurry. (4) The concentrate and tailings slurry are separated into solid and liquid by the action of the slurry pump, and then filtered. The filter water is discharged into the circulating water tank for reuse. After unloading, the concentrate and tailings are collected separately.

[0007] As a further improvement of the present invention, the concentration of the cyanide slag slurry is 35-45%, and the particle size of the screen is 60-100 mesh.

[0008] As a further improvement of the present invention, the addition of concentrated sulfuric acid is used to adjust the pH value to 4.5-5.5; the alkaline solution is NaOH or KOH solution, and the addition of alkaline solution is used to adjust the pH value to 7.5-8.5.

[0009] As a further improvement of the present invention, the collector includes a common collector and a modified collector in a mass ratio of 3-5:4-7, the amount of the collector added is 0.2-0.5 wt% of the total mass, the amount of the pine oil added is 0.1-0.3 wt% of the total mass, and the common collector is selected from at least one of dibutyl dithiophosphate, sodium butyl xanthate, sodium pentyl xanthate, and sodium ethyl xanthate.

[0010] As a further improvement of the present invention, the preparation method of the modified collector is as follows: S1. Preparation of modified magnetic iron oxide nanoparticles: Magnetic iron oxide nanoparticles were added to Tris-HCl solution, dopamine hydrochloride was added, the mixture was heated and stirred to react, centrifuged, washed, and dried to obtain modified magnetic iron oxide nanoparticles. S2. Preparation of poly(phenylene oxide) coated magnetic iron oxide nanoparticles: Modified magnetic iron oxide nanoparticles were added to water, phenol and formaldehyde were added, the mixture was stirred and mixed evenly, ammonia was added, the mixture was heated and stirred under reflux, the pH of the solution was adjusted, the reaction was continued, zinc chloride was added, the mixture was heated and cured, thermally decomposed, and ball milled to obtain poly(phenylene oxide) coated magnetic iron oxide nanoparticles. S3. Surface treatment: Poly(phenylene oxide) coated magnetic iron oxide nanoparticles are spread on the surface of a glass plate, oxygen is introduced, and plasma treatment is performed to obtain surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles. S4. Modification: Oleic acid and surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles were added to toluene, p-toluenesulfonic acid was added, the mixture was heated under reflux and stirred, filtered, washed, and dried to obtain modified nanoparticles. S5. Polymerization reaction: Modified nanoparticles and 4-allyloxybenzyl hydroxyxamic acid were added to acetonitrile. Under inert gas protection, an initiator was added, and the mixture was heated and stirred. The mixture was then filtered, washed, dried, and ball-milled to obtain the modified collector.

[0011] The collectors added in this invention include both common and modified collectors, which have a synergistic effect. While common collectors, such as sodium butyl xanthate, have good capture effects, they suffer from poor chemical stability, toxicity, foul odor, insufficient selectivity, flammability, and deliquescence, posing risks during storage and transportation, and resulting in environmental residues and high remediation costs. Therefore, this invention develops a modified collector.

[0012] The modified collector of this invention, after being modified with polydopamine on the surface of magnetic iron oxide nanoparticles, forms a phenolic resin layer on the adsorption surface. Then, intermolecular dehydration occurs, followed by intramolecular dehydration and dehydrogenation reactions, ultimately forming magnetic iron oxide nanoparticles coated with a conjugated poly(phenylene oxide) structure. After surface plasma treatment with oxygen-containing gas, the surface acquires hydroxyl groups, which react with oleic acid to graft oleic acid, and then copolymerize with 4-allyloxybenzyl hydroxyxamic acid. This results in a modified collector that carries a negative charge at pH 7.5-8.5, enabling it to electrostatically adsorb and deposit on the surface of the raw material cyanide slag, thus entering the foam layer. This reduces the amount of common collectors such as sodium butyl xanthate required, improving flotation selectivity. Furthermore, the modified collector is magnetic; under an applied magnetic field, the nanoparticles and the raw material cyanide slag aggregate through collisions caused by their movement in the flow field. The resulting complexes are then aggregated and recovered with the help of a permanent magnet, improving flotation efficiency. On the other hand, the hydrophobic nature of oleic acid chains and poly(phenylene oxide) facilitates efficient flotation. In the molecular structure of hydroxamic acid, N and O atoms can provide lone pairs of electrons, allowing it to easily coordinate with transition metal cations, thus forming stable five-membered ring chelates or relatively unstable four-membered ring chelates. It has a synergistic effect with sodium butylxanthate, especially when the pulp contains excess Cu. 2+ When oxidized, the poly(benzo[i]benzene) skeleton is oxidized first (quinone form), and it "sacrifices" itself by forming sp³ defects, protecting sodium butylxanthate from oxidation. At the same time, it overcomes the disadvantages of traditional collectors such as easy hydrolysis and oxidation (synergistic effect), high toxicity, foul odor (reduced dosage), poor selectivity (due to the special structure of modified collectors), flammability (poly(benzo[i]benzene) has flame-retardant effects), and environmental pollution (reduced dosage).

[0013] As a further improvement of the present invention, the pH value of the Tris-HCl solution in step S1 is 8.5-9.5, the mass ratio of the magnetic iron oxide nanoparticles to dopamine hydrochloride is 10:3-5, and the temperature of the heating and stirring reaction is 50-60℃, and the time is 2-4h.

[0014] As a further improvement of the present invention, in step S2, the mass ratio of the modified magnetic iron oxide nanoparticles, phenol, formaldehyde, and ammonia is 1:0.45-0.5:0.18-0.2:2-4; the heating and reflux stirring reaction time is 2-4 hours; the pH value of the solution is adjusted to 4-6; the heating reaction is continued for 2-4 hours; the amount of zinc chloride added is 1-2 wt% of the total mass of the system; the heating and curing temperature is 70-80℃ and the time is 22-26 hours; and the thermal decomposition temperature is 450-550℃ and the time is 2-4 hours.

[0015] As a further improvement of the present invention, the plasma treatment method in step S3 is to use a vacuum to 8-12 Pa, wash with oxygen 2-3 times, and then introduce oxygen to reach 20-40 Pa, with a power of 50-100 W and a treatment time of 5-10 min.

[0016] As a further improvement of the present invention, the mass ratio of oleic acid, surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles and p-toluenesulfonic acid in step S4 is 2-3:12-15:0.2-0.5, and the heating, reflux and stirring reaction time is 4-8 hours.

[0017] As a further improvement of the present invention, the mass ratio of the modified nanoparticles, 4-allyloxybenzyl hydroxamic acid and the initiator in step S5 is 10-15:2-4:0.1-0.2, the heating and stirring reaction temperature is 55-65℃, and the time is 3-5h. The initiator is selected from at least one of ammonium persulfate, potassium persulfate, and sodium persulfate.

[0018] The present invention has the following beneficial effects: 1. This invention utilizes a flotation process with the addition of a collector to achieve resource recycling of cyanide tailings and enrich the FeS2 component in gold cyanide tailings. After the sulfur is fully utilized, the iron is enriched into iron concentrate, thus achieving comprehensive utilization of both sulfur and iron resources while effectively protecting the environment. The entire production process includes raw material pretreatment, raw material pulping, flotation reagent addition, flotation enrichment, and solid-liquid separation. It achieves high sulfur and iron recovery rates, yielding high-quality pyrite concentrate with high FeS2 content, while simultaneously producing low-sulfur, high-silicon flotation cyanide slag.

[0019] 2. The production process of this invention has a good effect on cyanide removal, reducing the hazardous characteristics of tailings to general solid waste; it strengthens the flotation of sulfur concentrate, improves the recovery rate and yield of sulfur concentrate, and reduces the amount of solid waste generated; the waste gas from the activation tank is recovered in an organized manner, and after multi-stage alkaline absorption, the tail gas absorption cost is low and the effect is good; a large flotation machine is used to improve equipment efficiency and reduce energy consumption. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 Infrared spectrum of the modified collector prepared in Example 1.

[0022] Figure 2Hysteresis curves of the modified collector prepared in Example 1.

[0023] Figure 3 This is a process flow diagram of the method for improving the quality of pyrite concentrate powder recovered from cyanide tailings according to the present invention. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The average particle size of the magnetic iron oxide nanoparticles is 50-100 nm.

[0026] Preparation Example 1: Modified Collector The preparation method is as follows: S1. Preparation of modified magnetic iron oxide nanoparticles: 1g of magnetic iron oxide nanoparticles were added to 50mL of Tris-HCl solution with a pH of 8.5, 0.3g of dopamine hydrochloride was added, the mixture was heated to 50℃, stirred for 2h, centrifuged, washed, and dried to obtain modified magnetic iron oxide nanoparticles. S2. Preparation of poly(phenylene oxide) coated magnetic iron oxide nanoparticles: 1g of modified magnetic iron oxide nanoparticles were added to 50mL of water, along with 0.45g of phenol and 0.18g of formaldehyde. The mixture was stirred and mixed evenly. 2g of ammonia water was added, and the mixture was heated under reflux and stirred for 2h. The pH of the solution was adjusted to 4, and the reaction was continued for 2h. Zinc chloride was added at 1wt% of the total mass of the system. The mixture was heated to 70℃, cured for 22h, thermally decomposed at 450℃ for 2h, and ball-milled for 2h to obtain poly(phenylene oxide) coated magnetic iron oxide nanoparticles. S3. Surface treatment: Poly(phenylene oxide) coated magnetic iron oxide nanoparticles are evenly and thinly spread on the surface of a glass plate. The plate is evacuated to 8 Pa, purged twice with oxygen, and then oxygen is introduced to reach 20 Pa. The power is 50 W and the treatment time is 5 min to obtain surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles. S4. Modification: 0.2g of oleic acid and 1.2g of surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles were added to 50mL of toluene, and 0.02g of p-toluenesulfonic acid was added. The mixture was heated under reflux and stirred for 4h. After filtration, washing, and drying, the modified nanoparticles were obtained. S5. Polymerization reaction: 1 g of modified nanoparticles and 0.2 g of 4-allyloxybenzyl hydroxamic acid were added to 50 mL of acetonitrile. Under nitrogen protection, 0.01 g of potassium persulfate was added, and the mixture was heated to 55 °C and stirred for 3 h. The mixture was then filtered, washed, dried, and ball-milled for 2 h to obtain the modified collector. Figure 1 It can be seen that 3300-3600cm -1 The peak at 3010 cm⁻¹ represents the stretching vibration of hydroxyl and amino groups. -1 The position represents the =CH stretching vibration of an olefin, at 2922 cm⁻¹. -1 The peak at 2852 cm⁻¹ represents the asymmetric stretching vibration of the methylene group. -1 The peak at 1735 cm⁻¹ represents the symmetric stretching vibration of the methylene group. -1 The peak at 1650 cm⁻¹ represents the carbonyl stretching vibration. -1 The peak at 1608 cm⁻¹ corresponds to the C=O stretching vibration of the amide group. -1 1510cm -1 The peak at 1460 cm⁻¹ represents the skeletal vibration peak of the aromatic ring. -1 The peak at 1160 cm⁻¹ represents the asymmetric and symmetric bending vibrations of the CH bond. -1 The peak value for the stretching vibration of COC / CN is 920 cm⁻¹. -1 The stretching vibration peak of NO is 810 cm⁻¹. -1 720cm -1 The peak represents the out-of-plane bending vibration of the aromatic ring CH, <600 cm⁻¹ -1 The peak at this location corresponds to the stretching vibration of Fe-O. Figure 2 It can be seen that the saturation magnetization of the modified collector is 12.5 emu / g, the remanent magnetization is 2.1 emu / g, and the coercivity is 0.25 kOe.

[0027] Preparation Example 2: Modified Collector The preparation method is as follows: S1. Preparation of modified magnetic iron oxide nanoparticles: 1g of magnetic iron oxide nanoparticles were added to 50mL of Tris-HCl solution with a pH of 9.5, 0.5g of dopamine hydrochloride was added, the mixture was heated to 60℃, stirred for 4h, centrifuged, washed, and dried to obtain modified magnetic iron oxide nanoparticles. S2. Preparation of poly(phenylene oxide) coated magnetic iron oxide nanoparticles: 1g of modified magnetic iron oxide nanoparticles were added to 50mL of water, along with 0.5g of phenol and 0.2g of formaldehyde. The mixture was stirred and mixed evenly. 4g of ammonia water was added, and the mixture was heated under reflux and stirred for 4h. The pH of the solution was adjusted to 6, and the reaction was continued for 4h. Zinc chloride was added at 2wt% of the total mass of the system. The mixture was heated to 80℃, cured for 26h, thermally decomposed at 550℃ for 4h, and ball-milled for 2h to obtain poly(phenylene oxide) coated magnetic iron oxide nanoparticles. S3. Surface treatment: Poly(phenylene oxide) coated magnetic iron oxide nanoparticles are evenly and thinly spread on the surface of a glass plate. The plate is evacuated to 12 Pa, purged with oxygen 3 times, and then oxygen is introduced to reach 40 Pa. The power is 100 W and the treatment time is 10 min to obtain surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles. S4. Modification: Add 0.3g of oleic acid and 1.5g of surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles to 50mL of toluene, add 0.05g of p-toluenesulfonic acid, heat under reflux and stir for 4-8h, filter, wash and dry to obtain modified nanoparticles. S5. Polymerization reaction: 1.5g of modified nanoparticles and 0.4g of 4-allyloxybenzyl hydroxamic acid were added to 50mL of acetonitrile. Under nitrogen protection, 0.02g of ammonium persulfate was added, heated to 65℃, stirred for 5h, filtered, washed, dried, and ball-milled for 2h to obtain the modified collector.

[0028] Preparation Example 3: Modified Collector The preparation method is as follows: S1. Preparation of modified magnetic iron oxide nanoparticles: 1g of magnetic iron oxide nanoparticles were added to 50mL of Tris-HCl solution with pH 9, 0.4g of dopamine hydrochloride was added, the mixture was heated to 55℃, stirred for 3h, centrifuged, washed and dried to obtain modified magnetic iron oxide nanoparticles. S2. Preparation of poly(phenylene oxide) coated magnetic iron oxide nanoparticles: 1g of modified magnetic iron oxide nanoparticles were added to 50mL of water, along with 0.47g of phenol and 0.19g of formaldehyde. The mixture was stirred and mixed evenly. 3g of ammonia water was added, and the mixture was heated under reflux and stirred for 3h. The pH of the solution was adjusted to 5, and the reaction was continued for 3h. Zinc chloride was added at 1.5wt% of the total mass of the system. The mixture was heated to 75℃, cured for 24h, thermally decomposed at 500℃ for 3h, and ball-milled for 2h to obtain poly(phenylene oxide) coated magnetic iron oxide nanoparticles. S3. Surface treatment: Poly(phenylene oxide) coated magnetic iron oxide nanoparticles are evenly and thinly spread on the surface of a glass plate. The plate is evacuated to 10 Pa, purged with oxygen 3 times, and then oxygen is introduced to reach 30 Pa. The power is 75 W and the treatment time is 7 min to obtain surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles. S4. Modification: 0.25g of oleic acid and 1.35g of surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles were added to 50mL of toluene, and 0.035g of p-toluenesulfonic acid was added. The mixture was heated under reflux and stirred for 6h. After filtration, washing, and drying, the modified nanoparticles were obtained. S5. Polymerization reaction: 1.2g of modified nanoparticles and 0.3g of 4-allyloxybenzyl hydroxamic acid were added to 50mL of acetonitrile. Under nitrogen protection, 0.015g of sodium persulfate was added, heated to 60℃, stirred for 4h, filtered, washed, dried, and ball-milled for 2h to obtain the modified collector.

[0029] Comparative Preparation Example 1 The difference compared to Preparation Example 3 is that steps S2 and S3 were not performed.

[0030] The preparation method is as follows: S1. Preparation of modified magnetic iron oxide nanoparticles: 1g of magnetic iron oxide nanoparticles were added to 50mL of Tris-HCl solution with pH 9, 0.4g of dopamine hydrochloride was added, the mixture was heated to 55℃, stirred for 3h, centrifuged, washed and dried to obtain modified magnetic iron oxide nanoparticles. S2. Modification: Add 0.25g of oleic acid to 50mL of toluene, add 0.1g of N-hydroxysuccinimide and 0.1g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, stir and activate at 0℃ for 30min, add 1.35g of modified magnetic iron oxide nanoparticles, stir and react at room temperature for 10h, filter, wash, and dry to obtain modified nanoparticles; S3. Polymerization reaction: 1.2g of modified nanoparticles and 0.3g of 4-allyloxybenzyl hydroxamic acid were added to 50mL of acetonitrile. Under nitrogen protection, 0.015g of sodium persulfate was added, heated to 60℃, stirred for 4h, filtered, washed, dried, and ball-milled for 2h to obtain the modified collector.

[0031] Comparative Preparation Example 2 The difference from preparation example 3 is that step S5 was not performed.

[0032] The preparation method is as follows: S1. Preparation of modified magnetic iron oxide nanoparticles: 1g of magnetic iron oxide nanoparticles were added to 50mL of Tris-HCl solution with pH 9, 0.4g of dopamine hydrochloride was added, the mixture was heated to 55℃, stirred for 3h, centrifuged, washed and dried to obtain modified magnetic iron oxide nanoparticles. S2. Preparation of poly(phenylene oxide) coated magnetic iron oxide nanoparticles: 1g of modified magnetic iron oxide nanoparticles were added to 50mL of water, along with 0.47g of phenol and 0.19g of formaldehyde. The mixture was stirred and mixed evenly. 3g of ammonia water was added, and the mixture was heated under reflux and stirred for 3h. The pH of the solution was adjusted to 5, and the reaction was continued for 3h. Zinc chloride was added at 1.5wt% of the total mass of the system. The mixture was heated to 75℃, cured for 24h, thermally decomposed at 500℃ for 3h, and ball-milled for 2h to obtain poly(phenylene oxide) coated magnetic iron oxide nanoparticles. S3. Surface treatment: Poly(phenylene oxide) coated magnetic iron oxide nanoparticles are evenly and thinly spread on the surface of a glass plate. The plate is evacuated to 10 Pa, purged with oxygen 3 times, and then oxygen is introduced to reach 30 Pa. The power is 75 W and the treatment time is 7 min to obtain surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles. S4. Modification: Add 0.25g of oleic acid and 1.35g of surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles to 50mL of toluene, add 0.035g of p-toluenesulfonic acid, heat under reflux and stir for 6h, filter, wash and dry to obtain modified nanoparticles, which are the modified collector.

[0033] Comparative preparation example 3 The difference compared to preparation example 3 is that steps S4 and S5 were not performed.

[0034] The preparation method is as follows: S1. Preparation of modified magnetic iron oxide nanoparticles: 1g of magnetic iron oxide nanoparticles were added to 50mL of Tris-HCl solution with pH 9, 0.4g of dopamine hydrochloride was added, the mixture was heated to 55℃, stirred for 3h, centrifuged, washed and dried to obtain modified magnetic iron oxide nanoparticles. S2. Preparation of poly(phenylene oxide) coated magnetic iron oxide nanoparticles: 1g of modified magnetic iron oxide nanoparticles were added to 50mL of water, along with 0.47g of phenol and 0.19g of formaldehyde. The mixture was stirred and mixed evenly. 3g of ammonia water was added, and the mixture was heated under reflux and stirred for 3h. The pH of the solution was adjusted to 5, and the reaction was continued for 3h. Zinc chloride was added at 1.5wt% of the total mass of the system. The mixture was heated to 75℃, cured for 24h, thermally decomposed at 500℃ for 3h, and ball-milled for 2h to obtain poly(phenylene oxide) coated magnetic iron oxide nanoparticles. S3. Surface treatment: Poly(phenylene oxide) coated magnetic iron oxide nanoparticles are evenly and thinly spread on the surface of a glass plate. The plate is then evacuated to 10 Pa, purged with oxygen three times, and then oxygen is introduced to reach 30 Pa. The power is 75 W and the treatment time is 7 min to obtain surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles, which are the modified collectors.

[0035] Comparative preparation example 4 The difference compared to preparation example 3 is that steps S2 to S5 were not performed.

[0036] The preparation method is as follows: S1. Preparation of modified magnetic iron oxide nanoparticles: 1g of magnetic iron oxide nanoparticles were added to 50mL of Tris-HCl solution with a pH of 9, and 0.4g of dopamine hydrochloride was added. The mixture was heated to 55℃ and stirred for 3h. After centrifugation, washing, and drying, modified magnetic iron oxide nanoparticles were obtained, which are the modified collectors.

[0037] Example 1 like Figure 3 This embodiment describes a method for improving the quality of pyrite concentrate powder recovered from cyanide tailings, comprising the following steps: (1) Mix raw cyanide slag with water to make cyanide slag slurry with a concentration of 40±5%, fix a 60-mesh screen to filter out sand and gravel impurities, and transport it to the activation tank. (2) Add concentrated sulfuric acid to the activation tank to adjust the pH value to 4.5-5.5, so that the cyanide ions are converted into hydrogen cyanide gas and escape from the slurry into the waste gas absorption treatment device; add alkaline solution to adjust the pH value to 7.5-8.5 to reduce the unorganized escape of cyanide in the subsequent process; add a collector, the amount of which is 0.3wt% of the total mass; add pine oil, the amount of which is 0.2wt% of the total mass; the slurry particles selectively adhere to the surface of the bubbles, and the obtained slurry overflows to the flotation production device. The collector includes a common collector and a modified collector prepared in Preparation Example 1, with a mass ratio of 3:4; (3) The slurry overflowing from the activation tank first enters the primary roughing tank. Under the action of stirring and blowing, the slurry particles containing FeS2 float with the bubbles, are scraped off by the scraper, and flow into the primary cleaning tank along the flow channel. Similarly, under the action of stirring and blowing, the slurry particles containing FeS2 are further enriched and purified in the primary cleaning tank, and flow to the secondary cleaning tank. After being enriched and purified again, they are scraped off by the scraper and flow into the concentrate slurry underground tank. The slurry after primary roughing is drawn into the secondary roughing equipment through the gate channel between the flotation cells under the action of liquid level difference and flotation machine stirring and self-aspiration. Under the action of stirring and blowing, the FeS2 particles floating with the bubbles in the secondary roughing equipment are scraped off and returned to the primary roughing equipment along the flow channel. The slurry after secondary roughing enters the first and second scavenging flotation cells in sequence to further recover the FeS2 slurry particles and maximize the recovery rate. Finally, the remaining slurry flows into the tailings slurry underground tank. (4) The concentrate and tailings slurries are pumped to their respective intermediate buffer tanks, which are equipped with stirring devices to keep the slurry uniform and prevent sedimentation. Under the action of a high-lift, high-flow slurry pump, the concentrate and tailings slurries are fed into a filter press to achieve solid-liquid separation. After the filter chamber of the filter press is full of material, the slurry pump stops, and 0.8MPa compressed air is introduced into the filter chamber to further reduce the moisture content of the filter cake. The filter water is collected and discharged into the workshop's circulating water pool for reuse. After unloading, the concentrate and tailings are stored in their respective sites as high-quality pyrite concentrate powder (concentrate) and low-sulfur, high-silica flotation cyanide slag (tailings), respectively.

[0038] Example 2 The only difference from Example 1 is that the collector includes a common collector and the modified collector prepared in Preparation Example 2, in a mass ratio of 5:7.

[0039] Example 3 The only difference from Example 1 is that the collector includes a common collector and the modified collector prepared in Preparation Example 3, in a mass ratio of 4:5.

[0040] Comparative Examples 1-4 The only difference from Example 3 is that the modified collector was prepared from Comparative Preparation Examples 1-4.

[0041] Comparative Example 5 The only difference from Example 3 is that the modified collector is replaced by magnetic iron oxide nanoparticles of equal mass.

[0042] Comparative Example 6 The only difference from Example 3 is that the collector is a single sodium butyl xanthate.

[0043] Comparative Example 7 The only difference from Example 3 is that the collector is the modified collector prepared in Preparation Example 3.

[0044] Test Example 1 The methods in Examples 1-3 and Comparative Examples 1-7 were evaluated, and the results are shown in Table 1.

[0045] Table 1

[0046] As can be seen from the table above, the methods in Examples 1-3 of this invention have a high sulfur recovery rate and a high FeS2 content in the high-quality pyrite concentrate powder.

[0047] 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 principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of improving the quality of pyrite concentrate fines for recovery of cyanide tailings, characterized by, Includes the following steps: (1) The raw material cyanide tailings are mixed with water to make cyanide slag slurry, which is filtered through a fixed screen to remove sand and gravel impurities and then transported to the activation tank. (2) Add concentrated sulfuric acid to the activation tank to convert cyanide into hydrogen cyanide gas, and then add alkaline solution, collector and pine oil to obtain slurry; (3) Under the action of stirring and blowing, the slurry containing FeS2 particles floats to the surface with the air bubbles. Under the action of continued stirring and blowing, the slurry containing FeS2 particles are enriched and purified, and scraped out by the scraper. Under the action of liquid level difference and self-absorption of the flotation machine, FeS2 slurry particles are recovered to obtain concentrate slurry, and the residue is tailings slurry. (4) The concentrate and tailings slurry are separated into solid and liquid by the action of the slurry pump, and then filtered. The filter water is discharged into the circulating water tank for reuse. After unloading, the concentrate and tailings are collected separately.

2. The method for improving the quality of pyrite concentrate powder recovered from cyanide tailings according to claim 1, characterized in that, The concentration of the cyanide slag slurry is 35-45%, and the particle size of the screen is 60-100 mesh.

3. The method of improving the quality of pyrite concentrate fines for recovery of cyanidation tailings according to claim 1, characterized in that, The pH value is adjusted to 4.5-5.5 by adding concentrated sulfuric acid; the alkaline solution is NaOH or KOH solution, and the pH value is adjusted to 7.5-8.5 by adding alkaline solution.

4. The method of improving the quality of pyrite concentrate fines for recovery of cyanidation tailings according to claim 1, characterized in that, The collector includes a common collector and a modified collector in a mass ratio of 3-5:4-7. The amount of the collector added is 0.2-0.5 wt% of the total mass, and the amount of pine oil added is 0.1-0.3 wt% of the total mass. The common collector is selected from at least one of dibutyl dithiophosphate, sodium butyl xanthate, sodium pentyl xanthate, and sodium ethyl xanthate.

5. The method for improving the quality of pyrite concentrate powder recovered from cyanide tailings according to claim 4, characterized in that, The modified collector is prepared as follows: S1. Preparation of modified magnetic iron oxide nanoparticles: Magnetic iron oxide nanoparticles were added to Tris-HCl solution, dopamine hydrochloride was added, the mixture was heated and stirred to react, centrifuged, washed, and dried to obtain modified magnetic iron oxide nanoparticles. S2. Preparation of poly(phenylene oxide) coated magnetic iron oxide nanoparticles: Modified magnetic iron oxide nanoparticles were added to water, phenol and formaldehyde were added, the mixture was stirred and mixed evenly, ammonia was added, the mixture was heated and stirred under reflux, the pH of the solution was adjusted, the reaction was continued, zinc chloride was added, the mixture was heated and cured, thermally decomposed, and ball milled to obtain poly(phenylene oxide) coated magnetic iron oxide nanoparticles. S3. Surface treatment: Poly(phenylene oxide) coated magnetic iron oxide nanoparticles are spread on the surface of a glass plate, oxygen is introduced, and plasma treatment is performed to obtain surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles. S4. Modification: Oleic acid and surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles were added to toluene, p-toluenesulfonic acid was added, the mixture was heated under reflux and stirred, filtered, washed, and dried to obtain modified nanoparticles. S5. Polymerization reaction: Modified nanoparticles and 4-allyloxybenzyl hydroxyxamic acid were added to acetonitrile. Under inert gas protection, an initiator was added, and the mixture was heated and stirred. The mixture was then filtered, washed, dried, and ball-milled to obtain the modified collector.

6. The method for improving the quality of pyrite concentrate powder recovered from cyanide tailings according to claim 5, characterized in that, In step S1, the pH value of the Tris-HCl solution is 8.5-9.5, the mass ratio of the magnetic iron oxide nanoparticles to dopamine hydrochloride is 10:3-5, and the heating and stirring reaction temperature is 50-60℃ for 2-4 hours.

7. The method of improving the quality of pyrite concentrate fines for recovery of cyanidation tailings according to claim 5, characterized in that, In step S2, the mass ratio of modified magnetic iron oxide nanoparticles, phenol, formaldehyde, and ammonia is 1:0.45-0.5:0.18-0.2:2-4. The heating and reflux stirring reaction time is 2-4 hours. The pH of the solution is adjusted to 4-6. The heating reaction is continued for 2-4 hours. The amount of zinc chloride added is 1-2 wt% of the total mass of the system. The heating and curing temperature is 70-80℃ and the time is 22-26 hours. The thermal decomposition temperature is 450-550℃ and the time is 2-4 hours.

8. The method of improving the quality of pyrite concentrate fines for recovery of cyanidation tailings according to claim 5, characterized in that, The plasma treatment method described in step S3 involves evacuating to 8-12 Pa, purging with oxygen 2-3 times, then introducing oxygen to reach 20-40 Pa, with a power of 50-100 W and a treatment time of 5-10 min.

9. The method for improving the quality of pyrite concentrate powder recovered from cyanide tailings according to claim 4, characterized in that, In step S4, the mass ratio of oleic acid, surface-treated poly(phenylene oxide) coated magnetic iron oxide nanoparticles, and p-toluenesulfonic acid is 2-3:12-15:0.2-0.5, and the heating, reflux, and stirring reaction time is 4-8 hours.

10. The method for improving the quality of pyrite concentrate powder recovered from cyanide tailings according to claim 5, characterized in that, In step S5, the mass ratio of the modified nanoparticles, 4-allyloxybenzyl hydroxamic acid, and the initiator is 10-15:2-4:0.1-0.

2. The heating and stirring reaction is carried out at a temperature of 55-65°C for 3-5 hours. The initiator is selected from at least one of ammonium persulfate, potassium persulfate, and sodium persulfate.

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