A method for selective separation of copper and sulfur based on asynchronous flotation-subsection inhibition

Abstract

The application discloses a copper-sulfur selective separation method based on asynchronous flotation-stepwise inhibition. The copper-sulfur raw ore is subjected to one-stage grinding and two-stage classification to obtain coarse-grained sediment and fine-grained overflow; the coarse-grained sediment is subjected to flash flotation under the condition of pH 8.0-9.0 to obtain a coarse-grained copper concentrate, and the tailings of the flash flotation are returned to regrinding; the fine-grained overflow is subjected to copper flotation by adding a dispersing agent and an organic inhibitor under the condition of pH 7.5-9.5 to obtain a fine-grained copper concentrate and a copper tailing; and the copper tailing is subjected to sulfur flotation by adding an activator to obtain a sulfur concentrate. The application is aimed at the differential response of coarse-grained and fine-grained minerals to the inhibition intensity, the low-alkali lime is used for moderate inhibition in the coarse-grained section, and the organic inhibitor is used for selective pyrite inhibition in the fine-grained section, so that stepwise inhibition is realized, the sulfur concentrate is recovered from the tailings, and the method has the advantages of high separation efficiency, comprehensive recovery of copper and sulfur resources, low reagent consumption and environmental friendliness.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, specifically relating to a copper-sulfur selective separation method based on asynchronous flotation and stepwise suppression. Background Technology

[0002] Chalcopyrite often occurs in close association with pyrite, and copper-sulfur flotation separation is the core process for copper metal recovery. With the increasing depletion of easily beneficiated copper-sulfur ores, the particle size of the target minerals is becoming increasingly fine, and the distribution of coarse, medium, and fine-grained minerals in the ore is becoming more uneven. Studies have shown that the flotation kinetics and optimal flotation conditions differ significantly among different particle sizes of chalcopyrite. Coarse-grained chalcopyrite, due to its large mass and high momentum, requires moderate turbulence intensity and a stable froth layer for effective recovery; excessive agitation can actually cause it to detach from the bubbles. Fine-grained chalcopyrite, due to its large specific surface area and high surface energy, is highly prone to non-selective agglomeration and heterogeneous aggregation, and is easily mechanically entrained into the froth product in high-alkali, high-viscosity slurries. These differences in the flotation characteristics of different particle sizes make it difficult to achieve optimal recovery for all particle sizes under a single flotation condition.

[0003] Several technologies have been explored for asynchronous processing of minerals of different particle sizes. Flash flotation technology feeds the classifying sand from the grinding and classification circuit into a flash flotation machine, utilizing the characteristics of fully liberated coarse particles and low mud content in the sand to achieve rapid recovery of coarse target minerals. It has mature industrial applications in fields such as gold beneficiation. Asynchronous flotation technology, based on differences in mineral floatability, flotation speed patterns, and disseminated particle size characteristics, divides traditional roughing into multiple roughing stages, each employing different reagent regimes and flotation methods. Existing patents disclose low-alkali asynchronous separation methods for arsenic-containing copper sulfide ores and asynchronous flotation methods for high-altitude, fine-particle disseminated copper ores in stockpiles. However, existing asynchronous flotation methods focus on the step-by-step flotation itself, still employing similar suppression strategies for different particle sizes, all using lime as the main depressant under high-alkalinity conditions, failing to design differentiated suppression schemes based on the characteristics of different particle sizes.

[0004] In the area of ​​copper-sulfur separation inhibitors, traditional processes mainly employ high-alkali lime to inhibit pyrite. However, this method has significant drawbacks. Under high alkalinity conditions, the slurry becomes viscous, leading to severe mechanical entrainment of fine-grained minerals. Extensive use of lime causes pipe scaling, reduces the recovery rate of associated precious metals, and makes subsequent activation and recovery of pyrite strongly inhibited by lime difficult. In recent years, researchers have developed various organic inhibitors that selectively inhibit pyrite under low alkalinity conditions, such as ore-derived fulvic acid, sodium tricarboxymethyl dithiocarbonate, locust bean gum, and levodopa. These inhibitors can achieve selective inhibition of pyrite under low alkalinity conditions, avoiding many of the drawbacks of the high-alkali lime process. However, current technologies have not yet systematically coupled low-alkalinity organic inhibitors with flash flotation and asynchronous flotation to form a stepwise inhibition reagent regime targeting different particle sizes.

[0005] More importantly, there is a fundamental difference in the tolerance of coarse-grained and fine-grained minerals to the intensity of inhibition. Coarse-grained pyrite, due to its large mass and high momentum, requires strong inhibition conditions to effectively prevent it from floating. Fine-grained pyrite, on the other hand, due to its small mass, can be effectively inhibited under low-alkali and low-viscosity conditions, even without the addition of strong inhibitors, by using dispersants to remove the fine mud covering, relying on the selective adsorption of organic inhibitors. However, the current process uses uniform flotation conditions and inhibition intensities for different particle sizes, resulting in the loss of some copper minerals in the coarse-grained segment due to excessive inhibition, and the inclusion of large amounts of pyrite and gangue fine mud in the fine-grained segment due to high alkali and high viscosity.

[0006] In summary, the core challenge of existing copper-sulfur separation technologies in processing minerals of different particle sizes lies in the significant differences in optimal flotation conditions and suppression intensities between coarse and fine-grained minerals. Current processes still employ uniform flotation conditions and lime suppression systems, leading to the loss of coarse particles due to over-suppression or over-grinding, and the entrainment of fine particles due to high alkali and high viscosity, making it difficult to simultaneously achieve high copper concentrate grades and recovery rates. Therefore, there is an urgent need to develop a copper-sulfur selective separation method that couples grinding classification, flash flotation, and stepwise suppression. This method should design differentiated flotation conditions and suppression schemes based on the different flotation characteristics of coarse and fine particles, achieving rapid recovery of coarse particles and selective separation of fine particles. Summary of the Invention

[0007] The purpose of this invention is to provide a copper-sulfur selective separation method based on asynchronous flotation and stepwise suppression.

[0008] The objective of this invention is achieved as follows: the copper-sulfur selective separation method based on asynchronous flotation-step suppression includes classification and flotation steps, specifically including: A. Classification: 1) After grinding the copper-sulfur ore, it is fed into the first stage classification equipment in sequence to obtain the return sand a and the overflow b of the first stage classification equipment. The return sand a of the first stage classification equipment is returned to the first stage ball mill. 2) The overflow b from the first stage grading equipment is fed into the second stage grading equipment to obtain the sediment c from the second stage grading equipment and the overflow d from the second stage grading equipment; B. Flotation: 1) After adjusting the pH value of the sediment c in the second stage classification equipment to 8.0~9.0, add selective collector and frother for flotation to obtain coarse copper concentrate e and flotation tailings f. The flotation tailings are returned to the first stage ball mill. 2) After adjusting the pH value of the overflow d of the second stage classifier to 7.5~9.5, add dispersant, organic inhibitor, collector and frother for flotation to obtain fine copper concentrate g and copper tailings h; 3) Add activator, collector and frother to copper tailings h and perform flotation to obtain sulfur concentrate i and tailings j.

[0009] The specific steps are as follows: (1) One-stage grinding and two-stage classification: After the copper-sulfur ore is fed into the first-stage ball mill for grinding, it is fed into the first-stage classification equipment and the second-stage classification equipment in sequence for classification; the return sand from the first-stage classification equipment is returned to the first-stage ball mill, the overflow from the first-stage classification equipment is fed into the second-stage classification equipment, all the underflow from the second-stage classification equipment is fed into the flash flotation operation, and the overflow from the second-stage classification equipment is fed into the subsequent flotation operation. (2) Coarse flash flotation: All the sand from the second stage classification equipment in step (1) is fed into the flash flotation operation. Selective collectors and frothers are added under pH 8.0-9.0 conditions to carry out flash flotation, and coarse copper concentrate and flash flotation tailings are obtained. The flash flotation tailings are returned to the first stage ball mill. (3) Fine-grained copper flotation: The overflow of the second stage classification equipment in step (1) is fed into the flotation operation. Dispersant, organic inhibitor, collector and frother are added under pH 7.5-9.5 conditions to carry out flotation and obtain fine-grained copper concentrate and copper tailings. (4) Sulfur flotation: Add activator, collector and frother to the copper tailings in step (3) and carry out sulfur flotation to obtain sulfur concentrate and tailings.

[0010] in: In step (1), the first stage overflow fineness is -0.074mm, accounting for 40%-60%, and the second stage overflow fineness is -0.074mm, accounting for 70%-90%.

[0011] The slurry concentration for flash flotation in step (2) is 40%-55%, and the flotation time is 2-5 min.

[0012] The pH adjuster mentioned in step (2) is lime, which adjusts the pH of the flotation pulp to 8.0~9.0; the selective collector is at least one of Z-200, butyl xanthate or ethyl xanthate, with a dosage of 30-100 g / t; the frother is No. 2 oil or MIBC, with a dosage of 30-100 g / t.

[0013] The flash flotation concentrate described in step (2) can be used directly as the final copper concentrate product or enter the subsequent beneficiation operation for beneficiation.

[0014] The dispersant in step (3) is at least one of sodium hexametaphosphate, water glass or carboxymethyl cellulose, and the dosage is 200-1000 g / t; the organic inhibitor is at least one of legume polysaccharide inhibitor, levodopa, diosmin or sodium dimethyl dithiocarbamate, and the dosage is 100-500 g / t.

[0015] The collector mentioned in step (3) is at least one of butyl xanthate, pentyl xanthate or Z-200, with a dosage of 50-200 g / t, and the foaming agent is No. 2 oil or MIBC, with a dosage of 20-50 g / t.

[0016] The slurry mass concentration of the fine-particle flotation in step (3) is 25%-40%, and copper concentrate is obtained through one roughing, multiple cleaning and multiple scavenging.

[0017] In the flotation process described in step (3), organic inhibitors are added to maintain the inhibition environment during the fine selection operation, with an addition amount of 100-300 g / t; collectors and frothers are added in stages during the scavenging operation, with the addition amount of collectors being 10-50 g / t and the addition amount of frothers being 5-20 g / t.

[0018] The activator in step (4) is copper sulfate or lead nitrate, with a dosage of 200-1000 g / t; the collector is either butyl xanthate or pentyl xanthate, with a dosage of 100-200 g / t; the frother is No. 2 oil or MIBC, with a dosage of 30-100 g / t; and the sulfur concentrate is obtained through one roughing, multiple cleaning, and multiple scavenging processes.

[0019] Compared with the prior art, the present invention has the following advantages: (1) This invention proposes a novel approach to selective copper-sulfur separation: asynchronous flotation with stepwise suppression. Through a single grinding stage and two-stage classification stages, mineral particles are separated into two independent products: coarse-grained underflow and fine-grained overflow. These are processed asynchronously using flash flotation and conventional flotation, respectively. A stepwise suppression reagent regime is designed to address the differentiated response characteristics of minerals of different particle sizes to suppression intensity. While existing asynchronous flotation technologies have addressed the stepwise recovery of minerals with different floatability, they all employ a single suppression system based on lime, failing to precisely adapt suppression strategies according to particle size differences. This invention elevates asynchronous flotation from a simple process stepwise approach to a dual asynchronous approach of flotation conditions and suppression intensity, achieving independent separation of coarse and fine particles in their respective optimal flotation environments. This fundamentally solves the technical problem of mutual interference between minerals of different particle sizes in traditional single flotation processes.

[0020] (2) This invention fully explores and utilizes the essential differences in the tolerance of coarse and fine-grained minerals to the intensity of inhibition. Coarse-grained pyrite, due to its large mass and high momentum, has a high energy barrier to detach from the bubble surface, requiring strong inhibition conditions to effectively prevent its floatation; fine-grained pyrite, due to its small mass and low inertia, can be effectively inhibited under low-alkali and low-viscosity conditions without relying on strong inhibitors, after the fine mud covering is eliminated with the help of dispersants, by relying on the selective chemical adsorption of organic inhibitors. Based on the above-mentioned differences in inhibition response dependent on particle size, this invention uses lime as an inhibitor in the coarse flash flotation section, utilizing its moderate inhibition effect on coarse-grained pyrite under pH 8.0-9.0 conditions, and combining it with a highly selective collector to achieve rapid recovery of coarse-grained chalcopyrite; in the fine-grained flotation section, organic inhibitors are used instead of lime to achieve selective inhibition of fine-grained pyrite under low-alkali conditions of pH 7.5-9.5. This stepwise inhibition design, which uses lime for coarse particles and organic inhibitors for fine particles, precisely matches the different inhibition strength requirements of minerals of different particle sizes. It avoids the loss of coarse particles due to over-inhibition and the entrainment of fine particles due to high alkali in the traditional process caused by the mismatch between inhibition strength and particle size.

[0021] (3) In the fine-particle flotation stage, this invention employs low-alkalinity organic inhibitors to selectively inhibit pyrite, fundamentally eliminating the negative impact of high-alkali lime processes on fine-particle flotation. In traditional high-alkali lime processes, a large number of calcium ions react with carbonate and sulfate ions in the pulp to form fine calcium salt precipitates. These precipitates adsorb onto the surface of bubbles, making the foam abnormally stable. In addition, the viscosity of the pulp increases significantly under high-alkalinity conditions, resulting in a large amount of fine-particle chalcopyrite and gangue slime being mechanically carried into the foam product. In the fine-particle stage, this invention abandons the lime inhibition path and instead uses organic inhibitors such as legume polysaccharide inhibitors, levodopa, diosmin, or sodium dimethyl dithiocarbamate. Under low-alkalinity conditions, the active groups in the inhibitor molecules selectively chemically adsorb onto the iron sites on the pyrite surface, forming a hydrophilic film layer to hinder the adsorption of collectors on the pyrite surface. The low-alkalinity flotation environment effectively reduces the viscosity of the pulp, avoids excessive foam stability and mechanical entrainment of fine mud caused by high alkali, and significantly improves the grade and recovery rate of fine copper concentrate.

[0022] (4) This invention organically integrates flash flotation technology with the grinding and classification process, forming a closed-loop circulation system of "classification-flash flotation-return grinding". All the sludge from the second-stage classification equipment is directly fed into the flash flotation operation. Taking advantage of the technical advantage of flash flotation in processing coarse-grained minerals under high-concentration conditions, it realizes the rapid recovery of already liberated coarse-grained chalcopyrite. The flash flotation tailings are returned to the first-stage ball mill for regrinding, giving the intergrowth minerals a further opportunity for liberation; the flash flotation concentrate is directly used as the final copper concentrate product or enters subsequent beneficiation operations. This design avoids over-grinding losses and metal loss caused by returning liberated coarse-grained minerals to the mill, while reducing the grinding cycle load, improving grinding and classification conditions, and realizing the beneficiation principle of "recovering as soon as possible".

[0023] (5) This invention achieves deep coupling of three operating units—grinding, classification, and flotation—through a process configuration of one-stage grinding and two-stage classification. The first-stage classification equipment and the ball mill form a closed-loop grinding system, controlling the overflow fineness of the first-stage classification to be -0.074mm, accounting for 40%-60%. The second-stage classification equipment performs secondary classification on the overflow of the first-stage classification, controlling the overflow fineness of the second-stage classification to be -0.074mm, accounting for 70%-90%. The underflow from the second-stage classification enters flash flotation, and the overflow enters conventional flotation. This two-stage classification configuration achieves precise particle size separation of the slurry without increasing the number of mills, allowing coarse and fine minerals to enter their respective suitable flotation operations, avoiding the drawbacks of insufficient classification accuracy in traditional single-stage classification processes, which leads to coarse particles entering fine flotation or fine particles being returned for regrinding.

[0024] (6) In the method described in this invention, the flotation conditions and reagent regimes of the coarse flash flotation section and the fine flotation section are designed independently and do not interfere with each other. The coarse section uses a higher pulp concentration and a shorter flotation time, combined with highly selective collectors such as Z-200, butyl xanthate, or ethyl xanthate, to achieve rapid recovery of coarse minerals; the fine section uses a conventional flotation concentration and a complete roughing-cleaning-scavenging flotation process, combined with dispersants to eliminate fine mud covering and organic inhibitors to selectively inhibit pyrite, to achieve selective separation of fine minerals. The two asynchronous operations avoid the inherent contradiction in traditional processes of sacrificing other particle sizes to accommodate one particle size, and achieve simultaneous improvement in both copper concentrate grade and recovery rate.

[0025] (7) This invention can achieve highly efficient and selective separation of copper and sulfur under low alkalinity conditions (pH 8.0-9.0 for coarse particles and pH 7.5-9.5 for fine particles). The amount of lime used in the coarse particles is only 200-800 g / t, and no lime is needed at all in the fine particles. Compared with the traditional high-alkali lime process, this invention significantly reduces lime consumption and eliminates a series of problems caused by high-alkali environment, such as sticky slurry, increased foam entrainment, scaling of pipes and equipment, inhibition of associated precious metals in the lime system and difficulty in recovery, and high cost of treating tailings with excessive alkalinity. This significantly reduces mineral processing costs and environmental impact. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0027] The present invention will be further described below with reference to embodiments, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0028] The copper-sulfur selective separation method based on asynchronous flotation-step suppression described in this invention includes a classification and flotation step, specifically including: A. Classification: 1) After grinding the copper-sulfur ore, it is fed into the first stage classification equipment in sequence to obtain the return sand a and the overflow b of the first stage classification equipment. The return sand a of the first stage classification equipment is returned to the first stage ball mill. 2) The overflow b from the first stage grading equipment is fed into the second stage grading equipment to obtain the sediment c from the second stage grading equipment and the overflow d from the second stage grading equipment; B. Flotation: 1) After adjusting the pH value of the sediment c in the second stage classification equipment to 8.0~9.0, add selective collector and frother for flotation to obtain coarse copper concentrate e and flotation tailings f. The flotation tailings are returned to the first stage ball mill. 2) After adjusting the pH value of the overflow d of the second stage classifier to 7.5~9.5, add dispersant, organic inhibitor, collector and frother for flotation to obtain fine copper concentrate g and copper tailings h; 3) Add activator, collector and frother to copper tailings h and perform flotation to obtain sulfur concentrate i and tailings j.

[0029] The selective collector mentioned in step 1) is Z-200, butyl xanthate, or ethyl xanthate.

[0030] The foaming agent mentioned in step 1) is No. 2 oil or MIBC.

[0031] The dispersant mentioned in step 2) is sodium hexametaphosphate, water glass, or carboxymethyl cellulose.

[0032] The organic inhibitor mentioned in step 2) is a legume polysaccharide inhibitor, levodopa, diosmin, or sodium dimethyl dithiocarbamate.

[0033] The collector mentioned in step 2) is butyl xanthate, pentyl xanthate, or Z-200.

[0034] The foaming agent mentioned in step 2) is No. 2 oil or MIBC.

[0035] The activator mentioned in step 3) is copper sulfate or lead nitrate.

[0036] The collector mentioned in step 3) is butyl xanthate or pentyl xanthate.

[0037] The foaming agent mentioned in step 3) is No. 2 oil or MIBC.

[0038] The present invention will be further described below with reference to specific embodiments: Example 1

[0039] The copper-sulfur selective separation method based on asynchronous flotation-step suppression described in Example 1 consists of the following steps: (1) One-stage grinding and two-stage classification: Take a copper-sulfur ore with a copper grade of 0.85% and a sulfur grade of 18.6%. After the raw ore is fed into a ball mill for grinding, it is fed into a spiral classifier and a hydrocyclone for classification in sequence; the return sand from the spiral classifier is returned to the ball mill, and the overflow is fed into the hydrocyclone; all the underflow from the hydrocyclone is fed into flash flotation, and the overflow is fed into subsequent flotation operations; the fineness of the overflow from the first stage classification is -0.074 mm, accounting for 51%, and the fineness of the overflow from the second stage classification is -0.074 mm, accounting for 82%.

[0040] (2) Coarse flash flotation: All the sediment from the hydrocyclone in step (1) is fed into the flash flotation operation. The flash flotation pulp has a mass concentration of 45%. Under pH 8.5 conditions, 60 g / t of Z-200 and 50 g / t of No. 2 oil are added for flash flotation. The flotation time is 3 min to obtain coarse copper concentrate and flash flotation tailings. The flash flotation tailings are returned to the first-stage ball mill. (3) Fine-grained copper flotation: The overflow from the hydrocyclone in step (1) is fed into the flotation operation. The mass concentration of the roughing pulp is 30%. Under pH 8.0 conditions, 500 g / t of sodium hexametaphosphate, 200 g / t of levodopa, 100 g / t of butyl xanthate and 30 g / t of No. 2 oil are added for flotation. After one roughing, two cleaning and two scavenging, fine-grained copper concentrate and copper tailings are obtained. In the cleaning operation, 150 g / t of levodopa is added. In the scavenging operation, butyl xanthate (30 g / t of scavenging I and 15 g / t of scavenging II) and No. 2 oil (15 g / t of scavenging I and 8 g / t of scavenging II) are added in stages.

[0041] (4) Sulfur flotation: Add 500 g / t of copper sulfate, 150 g / t of butyl xanthate and 60 g / t of No. 2 oil to the copper tailings in step (3). After one roughing, two cleaning and two scavenging processes, sulfur concentrate and final tailings are obtained.

[0042] Comparative Example 1 (Conventional single flotation, without flash flotation) Comparative Example 1 is basically the same as Example 1, except that: in step (1), two-stage classification and flash flotation are not used. After the ore is ground by a ball mill, it is fed into a spiral classifier to form a closed circuit. The overflow fineness of the classification is -0.074mm, accounting for 65%. The classification overflow directly enters a single conventional flotation operation. Under pH 11.0 conditions, 3000 g / t of lime, 120 g / t of butyl xanthate, and 40 g / t of No. 2 oil are added for copper flotation. After one roughing, two cleaning, and two scavenging, fine-grained copper concentrate and copper tailings are obtained. Then, 500 g / t of copper sulfate, 150 g / t of butyl xanthate, and 60 g / t of No. 2 oil are added to the copper tailings for sulfur flotation to obtain sulfur concentrate and final tailings. The remaining conditions are the same as in Example 1.

[0043] Comparative Example 2 (conventional two-stage classification but without flash flotation) Comparative Example 2 is basically the same as Example 1, except that the hydrocyclone sediment obtained in step (1) is not sent to flash flotation, but is directly returned to the first ball mill for re-grinding; the hydrocyclone overflow is sent to conventional flotation. Step (2) is omitted. In step (3), copper flotation is carried out under pH 11.0 conditions with the addition of 3000 g / t lime, 120 g / t butyl xanthate and 40 g / t No. 2 oil. After one roughing, two cleaning and two scavenging processes, fine copper concentrate and copper tailings are obtained. Then, 500 g / t copper sulfate, 150 g / t butyl xanthate and 60 g / t No. 2 oil are added to the copper tailings for sulfur flotation to obtain sulfur concentrate and final tailings. The remaining conditions are the same as in Example 1.

[0044] Comparative Example 3 (coarse-grained segments were suppressed using high-alkali lime) Comparative Example 3 is basically the same as Example 1, except that in step (2) coarse flash flotation, 2000 g / t of lime, 80 g / t of butyl xanthate and 50 g / t of No. 2 oil are added under pH 11.0 conditions for flash flotation. The remaining steps (1), (3) and (4) are the same as in Example 1.

[0045] Comparative Example 4 (fine particles were suppressed with lime, without organic inhibitors) Comparative Example 4 is basically the same as Example 1, except that in step (3) fine copper flotation, 3000 g / t of lime is added at pH 11.0 to replace the organic inhibitor, and 500 g / t of sodium hexametaphosphate, 100 g / t of butyl xanthate and 30 g / t of No. 2 oil are added for flotation. After one roughing, two cleaning and two scavenging, fine copper concentrate and copper tailings are obtained. Then, 500 g / t of copper sulfate, 150 g / t of butyl xanthate and 60 g / t of No. 2 oil are added to the copper tailings for sulfur flotation to obtain sulfur concentrate and final tailings. The remaining steps (1) and (2) are the same as in Example 1.

[0046] Comparative Example 5 (lime was used to suppress both coarse and fine grains) The copper-sulfur separation flotation method described in Comparative Example 5 is basically the same as that in Example 1, except that: 2000 g / t of lime is added to the coarse-grained flash flotation section at pH 11.0, and 3000 g / t of lime is added to the fine-grained copper flotation section at pH 11.0, for a total lime dosage of 5000 g / t; after obtaining copper tailings from the fine-grained copper flotation, 500 g / t of copper sulfate, 150 g / t of butyl xanthate, and 60 g / t of No. 2 oil are added to it for sulfur flotation to obtain sulfur concentrate and final tailings. The rest is the same as in Example 1.

[0047] Comparative Example 6 (without dispersant) Comparative Example 6 is basically the same as Example 1, except that sodium hexametaphosphate dispersant is not added in step (3) of fine-grained copper flotation. The other reagents (200 g / t of levodopa, 100 g / t of butyl xanthate, and 30 g / t of No. 2 oil) and flotation conditions are the same as in Example 1. After obtaining copper tailings, 500 g / t of copper sulfate, 150 g / t of butyl xanthate, and 60 g / t of No. 2 oil are added to it for sulfur flotation to obtain sulfur concentrate and final tailings. The remaining steps (1) and (2) are the same as in Example 1.

[0048] Example 2

[0049] The copper-sulfur selective separation method based on asynchronous flotation-step suppression described in Example 2 consists of the following steps: (1) One-stage grinding and two-stage classification: Take the same ore as in Example 1, feed the raw ore into a ball mill for grinding, and then feed it into two hydrocyclones for classification in sequence; the underflow from the first hydrocyclone is returned to the first ball mill, and the overflow is fed into the second hydrocyclone; all the underflow from the second hydrocyclone is fed into flash flotation, and the overflow is fed into subsequent flotation operations; the overflow fineness of the first stage classification is -0.074mm, accounting for 45%, and the overflow fineness of the second stage classification is -0.074mm, accounting for 76%.

[0050] (2) Coarse flash flotation: The sediment from the second hydrocyclone in step (1) is fed into the flash flotation operation. The flash flotation pulp has a mass concentration of 50%. Under pH 8.0 conditions, 80 g / t of butyl xanthate and 60 g / t of MIBC are added for flash flotation. The flotation time is 4 min to obtain coarse copper concentrate and flash flotation tailings. The flash flotation tailings are returned to the first ball mill. (3) Fine-grained copper flotation: The overflow from the two-stage hydrocyclone in step (1) is fed into the flotation operation. The mass concentration of the roughing pulp is 35%. Under pH 8.5 conditions, 700 g / t of water glass, 300 g / t of leguminous polysaccharide inhibitor, 120 g / t of pentyl xanthate and 40 g / t of MIBC are added for flotation. After one roughing, three cleaning and three scavenging, fine-grained copper concentrate and copper tailings are obtained. In the cleaning operation, 200 g / t of leguminous polysaccharide inhibitor is added. In the scavenging operation, pentyl xanthate (40 g / t of scavenging I, 20 g / t of scavenging II, 10 g / t of scavenging III) and MIBC (20 g / t of scavenging I, 10 g / t of scavenging II, 5 g / t of scavenging III) are added in stages.

[0051] (4) Sulfur flotation: Add 600 g / t of copper sulfate, 180 g / t of pentyl xanthate and 80 g / t of MIBC to the copper tailings in step (3). After one roughing, two cleaning and two scavenging processes, sulfur concentrate and final tailings are obtained.

[0052] Example 3

[0053] The copper-sulfur selective separation method based on asynchronous flotation-step suppression described in Example 3 consists of the following steps: (1) First-stage grinding and two-stage classification: A copper-sulfur ore was taken, with a copper grade of 1.20% and a sulfur grade of 22.3%. The raw ore was fed into a first-stage ball mill for grinding, and then fed into a spiral classifier and a hydrocyclone for classification. The return sand from the spiral classifier was returned to the first-stage ball mill, and the overflow was fed into the hydrocyclone. All the underflow from the hydrocyclone was fed into flash flotation, and the overflow was fed into subsequent flotation operations. The overflow fineness of the first-stage classification was -0.074 mm, accounting for 55%, and the overflow fineness of the second-stage classification was -0.074 mm, accounting for 88%. (2) Coarse flash flotation: All the sediment from the hydrocyclone in step (1) is fed into the flash flotation operation. The flash flotation pulp has a mass concentration of 40%. Under pH 9.0 conditions, 100 g / t of ethyl xanthate and 80 g / t of No. 2 oil are added for flash flotation. The flotation time is 2 min to obtain coarse copper concentrate and flash flotation tailings. The flash flotation tailings are returned to the first-stage ball mill. (3) Fine-grained copper flotation: The overflow from the hydrocyclone in step (1) is fed into the flotation operation. The mass concentration of the roughing pulp is 30%. Under pH 7.5 conditions, 800 g / t of carboxymethyl cellulose, 400 g / t of diosmin, 150 g / t of Z-200 and 50 g / t of MIBC are added for flotation. After one roughing, two cleaning and two scavenging, fine-grained copper concentrate and copper tailings are obtained. In the cleaning operation, 250 g / t of diosmin is added. In the scavenging operation, Z-200 (scavenging I 40 g / t, scavenging II 20 g / t) and MIBC (scavenging I 20 g / t, scavenging II 10 g / t) are added in stages.

[0054] (4) Sulfur flotation: 400 g / t of lead nitrate, 200 g / t of butyl xanthate, and 100 g / t of No. 2 oil are added to the copper tailings from step (3). After one roughing, two cleaning, and two scavenging processes, sulfur concentrate and final tailings are obtained. Example 4 The copper-sulfur selective separation method based on asynchronous flotation-step suppression described in Example 4 consists of the following steps: (1) One-stage grinding and two-stage classification: Take a copper-sulfur ore with a copper grade of 0.62% and a sulfur grade of 25.8%. After the ore is fed into a ball mill for grinding, it is fed into two hydrocyclones for classification. The underflow from the first hydrocyclone is returned to the ball mill, and the overflow is fed into the second hydrocyclone. All the underflow from the second hydrocyclone is fed into flash flotation, and the overflow is fed into subsequent flotation operations. The overflow fineness of the first stage classification is -0.074 mm, accounting for 48%, and the overflow fineness of the second stage classification is -0.074 mm, accounting for 80%.

[0055] (2) Coarse-grained flash flotation: All the sediment from the hydrocyclone in step (1) is fed into the flash flotation operation. The flash flotation pulp has a mass concentration of 55%. Z-200 40 g / t and MIBC 40 g / t are added under pH 8.2 conditions for flash flotation. The flotation time is 5 min to obtain coarse-grained copper concentrate and flash flotation tailings. The flash flotation tailings are returned to the first-stage ball mill. (3) Fine-grained copper flotation: The overflow from the two-stage hydrocyclone in step (1) is fed into the flotation operation. The mass concentration of the roughing pulp is 35%. Under pH 9.0 conditions, 400 g / t of sodium hexametaphosphate, 350 g / t of sodium dimethyl dithiocarbamate, 80 g / t of butyl xanthate and 25 g / t of No. 2 oil are added for flotation. After one roughing, one cleaning and one scavenging, fine-grained copper concentrate and copper tailings are obtained. In the cleaning operation, 200 g / t of sodium dimethyl dithiocarbamate is added. In the scavenging operation, 25 g / t of butyl xanthate and 12 g / t of No. 2 oil are added.

[0056] (4) Sulfur flotation: Add 800 g / t of copper sulfate, 120 g / t of pentyl xanthate and 50 g / t of MIBC to the copper tailings in step (3). After one roughing, two cleaning and two scavenging processes, sulfur concentrate and final tailings are obtained.

[0057] The flotation effects of Examples 1-4 and Comparative Examples 1-6 are summarized, and their main flotation indicators are listed in Tables 1-2.

[0058] Table 1. Flotation test results of Example 1 and Comparative Examples 1-6

[0059] Table 2 Results of flotation tests in Examples 2-4

[0060] The data obtained from the flotation tests in Table 1-2 show that: (1) Comparative Example 1 adopted a conventional single flotation process. The ore was directly fed into the flotation process after a first-stage grinding. 3000 g / t lime was added to suppress pyrite under high alkalinity conditions of pH 11.0. This process did not classify the coarse and fine particles. The coarse chalcopyrite particles that had been liberated continued to collide with the steel balls in the grinding loop, resulting in unavoidable over-grinding. This over-grinded copper mineral was lost in subsequent operations due to its excessively fine particle size. At the same time, the fine chalcopyrite and gangue slime had extremely poor dispersibility in the high-alkalinity and high-viscosity slurry. A large amount of fine chalcopyrite was mechanically entrained into the tailings by the over-stabilized froth. The flotation results showed that the Cu grade of Comparative Example 1 was only 18.62% and the recovery rate was only 77.43%, which was 4.53 percentage points worse and 11.89 percentage points lower than that of Example 1, respectively. This demonstrates that in traditional single flotation processes, minerals of different particle sizes interfere with each other under the same flotation conditions. Coarse particles are lost due to over-grinding, and fine particles are lost due to entrainment, making it impossible to simultaneously improve grade and recovery rate.

[0061] (2) Although Comparative Example 2 used a two-stage classification to obtain coarse-grained underflow and fine-grained overflow, it did not include flash flotation. All coarse-grained underflow was returned to the ball mill for regrinding. Compared with Comparative Example 1, although the classification process removed some fine mud before flotation, reducing the interference of fine mud on flotation, the coarse-grained chalcopyrite that had been liberated in the underflow had to be returned to the ball mill for re-grinding due to the lack of a flash flotation recovery stage. This liberated coarse-grained mineral collided again with the grinding media in the ball mill, and its surface developed a large number of microcracks and new hydrophilic surfaces due to over-grinding, resulting in a significant decrease in floatability; some particles were further fragmented into fine particles, which greatly increased the difficulty of flotation recovery. The flotation results showed that the Cu grade of Comparative Example 2 was 19.15% and the recovery rate was 80.26%, which was slightly better than Comparative Example 1, but still worse than Example 1 by 3.47 percentage points and decreased by 9.06 percentage points, respectively. The results show that while grading can improve the sorting environment, if flash flotation is not configured to recover the dissociated coarse particles in a timely manner, the particle size separation advantage brought by grading will be greatly offset by the over-grinding of coarse particles and cannot be fully converted into an improvement in flotation performance.

[0062] (3) In Comparative Example 3, high-alkali lime suppression (pH 11.0, lime 2000 g / t) was used in the coarse-grain flash flotation section, while low-alkali suppression with levodopa was maintained in the fine-grained section. Under high-alkali conditions of pH 11.0, a large amount of OH-... - Ions and Ca in the pulp 2+ Competitive adsorption occurs on the surface of chalcopyrite. Some chalcopyrite surfaces lose their hydrophobicity due to the formation of hydrophilic copper hydroxide or calcium films, significantly reducing their adhesion strength to air bubbles. Even with high momentum, coarse-grained minerals struggle to adhere effectively to the bubble surface. Simultaneously, the ionic strength of the pulp increases sharply under high-alkali conditions, and double-layer compression alters the interparticle forces, leading to a decrease in selectivity in the flash flotation stage. Flotation results show that in Comparative Example 3, the Cu grade was 20.87%, and the recovery rate was 82.11%, representing a deterioration of 2.28 percentage points and a decrease of 7.21 percentage points compared to Example 1, respectively. This demonstrates that higher inhibition strength is not always better in the coarse-grained flash flotation stage. Excessive alkalinity and lime content can actually cause a hydrophilic transformation of the chalcopyrite surface, inhibiting its floatability. The coarse-grained stage should utilize moderately low-alkali conditions combined with a highly selective collector, relying on the momentum advantage of the coarse-grained minerals themselves to achieve rapid recovery, rather than indirectly improving selectivity by strongly inhibiting pyrite.

[0063] (4) In Comparative Example 4, lime was used to replace the levodopa organic inhibitor in the fine-particle flotation section (pH 11.0, lime 3000 g / t), while low-alkali flash flotation was maintained in the coarse-particle section (pH 8.5, lime 400 g / t). Under high-alkali conditions, a large amount of Ca... 2+ CO3 dissolved in the slurry 2- SO4 2-The formation of fine-grained calcium salt precipitates, which adsorb onto the bubble surface to form a composite bubble film, significantly enhances the mechanical strength and stability of the foam, making the foam layer less prone to rupture. Simultaneously, the high-alkalinity environment drastically increases the viscosity of the slurry, further reducing the settling rate of fine-grained minerals in the viscous medium, making it difficult to effectively separate fine-grained chalcopyrite from gangue slime within the foam layer. The combined effect of these two factors results in a large amount of non-targeted slime being mechanically carried into the concentrate product by the over-stabilized foam. Flotation results show that the Cu grade in Comparative Example 4 is only 18.94%, and the recovery rate is only 78.55%, representing a deterioration of 4.21 percentage points and a decrease of 10.77 percentage points compared to Example 1, respectively. The study demonstrates that while lime inhibition in the fine-grained flotation stage can achieve chemical inhibition of pyrite, the accompanying physical effects, such as increased pulp viscosity, overly stable foam, and intensified mechanical entrainment, have a serious negative impact on the selective separation of fine-grained minerals. Organic inhibitors, on the other hand, achieve inhibition through selective chemical adsorption under low alkalinity conditions without altering the rheological properties of the pulp, and thus have an irreplaceable advantage over lime in the fine-grained stage.

[0064] (5) Comparative Example 5 used high-alkali lime for suppression in both the coarse and fine-grained stages, with a total lime consumption of up to 5000 g / t. This comparative example vividly illustrates the superposition of all the negative effects of the high-alkali lime process in copper-sulfur separation: the inhibition of hydrophilicity on the chalcopyrite surface under high-alkali conditions in the coarse-grained stage led to a decrease in the coarse-grained recovery rate; mechanical entrainment under high-alkali and high-viscosity conditions in the fine-grained stage led to a deterioration in the concentrate grade; and excessive lime in both stages caused the slurry to become sticky and the bubbles to become overly stable. More seriously, the negative effects of the two stages were not simply additive, but were mutually transmitted and synergistically amplified through the slurry circulation medium, resulting in a severe loss of selectivity in the entire separation system. The flotation results showed that the Cu grade of Comparative Example 5 was only 17.23%, and the recovery rate was only 72.89%, which were 5.92 percentage points worse and 16.43 percentage points lower than those of Example 1, respectively. The study demonstrates that the stepwise inhibition strategy of "using lime for coarse particles and organic inhibitors for fine particles" is not a simple substitution of reagents, but rather a precise match based on the different requirements of different particle sizes for inhibition intensity and slurry environment. The use of a unified lime system in both stages contradicts the optimal conditions for the fine particle stage in terms of both chemical inhibition and physical environment, and the superimposed effect leads to a systematic deterioration of the sorting index.

[0065] (6) In Comparative Example 6, no dispersant was added in the fine-grained flotation section, and selective inhibition relied solely on levodopa. In the absence of a dispersant, strong non-selective heterogeneous agglomeration occurred between fine-grained chalcopyrite, fine-grained pyrite, and gangue slime due to differences in surface charge and hydrophobic interactions. In this agglomerate, the chalcopyrite particles were tightly wrapped by the hydrophilic pyrite and gangue slime, forming a "core-shell" structure. Levodopa molecules were physically blocked by the outer layer of slime and could not effectively act on the surface of the wrapped chalcopyrite; simultaneously, the collector could not penetrate the slime layer to reach the chalcopyrite surface for effective adsorption. The wrapped chalcopyrite could not effectively collide and adhere to the bubbles and entered the tailings with the agglomerates. The flotation results showed that the Cu grade of Comparative Example 6 was 20.46%, and the recovery rate was 84.33%, which were 2.69 percentage points worse and 4.99 percentage points lower than those of Example 1, respectively. This demonstrates that the function of dispersants in the fine-particle flotation stage is not simply to disperse slime, but to ensure that organic inhibitors and collectors can effectively reach their respective target mineral surfaces by eliminating heterogeneous agglomeration and blocking the formation of "core-shell" structures. The synergistic effect of dispersants and organic inhibitors is a necessary condition for achieving selective separation in the fine-particle stage, and neither can be dispensed with.

[0066] (7) Examples 2-4 respectively used three organic inhibitors: legume polysaccharide inhibitor, diosmin, and sodium dimethyl dithiocarbamate. Together with levodopa in Example 1, they covered the types of organic inhibitors defined in the claims. Although the molecular structures of the four organic inhibitors are different, they all contain active groups that can selectively chemically coordinate with iron sites on the surface of pyrite. Under low alkalinity conditions, they can selectively adsorb and inhibit pyrite, while having no significant effect on the surface of chalcopyrite. The coarse particles in each example were all flash flotation under low alkalinity conditions of pH 8.0-9.0; the fine particles were all selectively separated under low alkalinity conditions of pH 7.5-9.0. The Cu grade of the copper concentrate in each example was ≥22.41%, and the Cu recovery rate was ≥87.89%, which fully demonstrates that the technical solution of the present invention has a wide applicability to different types of organic inhibitors. Its core mechanism lies in the synergistic effect of particle size separation and stepwise inhibition, rather than relying on the specificity of a specific reagent. Compared with the traditional high-alkali lime process (Comparative Examples 1-5), this invention improves the copper concentrate grade by 3.79-6.39 percentage points and the copper recovery rate by 7.60-17.26 percentage points under low alkalinity conditions. At the same time, it fundamentally eliminates a series of problems caused by high-alkali environment, such as sticky slurry, excessively stable foam, pipe scaling, the inhibition of associated precious metals in alkaline system, making them difficult to recover, and the high cost of treating tailings with excessive alkalinity.

Claims

1. A method for selective separation of copper and sulfur based on asynchronous flotation and stepwise suppression, characterized in that, The copper-sulfur selective separation method based on asynchronous flotation-step suppression includes classification and flotation steps, specifically including: A. Classification: 1) After grinding the copper-sulfur ore, it is fed into the first stage classification equipment in sequence to obtain the return sand a and the overflow b of the first stage classification equipment. The return sand a of the first stage classification equipment is returned to the first stage ball mill. 2) The overflow b from the first stage grading equipment is fed into the second stage grading equipment to obtain the sediment c from the second stage grading equipment and the overflow d from the second stage grading equipment; B. Flotation: 1) After adjusting the pH value of the sediment c in the second stage classification equipment to 8.0~9.0, add selective collector and frother for flotation to obtain coarse copper concentrate e and flotation tailings f. The flotation tailings are returned to the first stage ball mill. 2) After adjusting the pH value of the overflow d of the second stage classifier to 7.5~9.5, add dispersant, organic inhibitor, collector and frother for flotation to obtain fine copper concentrate g and copper tailings h; 3) Add activator, collector and frother to copper tailings h and perform flotation to obtain sulfur concentrate i and tailings j.

2. The copper-sulfur selective separation method based on asynchronous flotation-step suppression according to claim 1, characterized in that, The selective collector mentioned in step 1) is Z-200, butyl xanthate, or ethyl xanthate.

3. The copper-sulfur selective separation method based on asynchronous flotation-step suppression according to claim 1, characterized in that, The foaming agent mentioned in step 1) is No. 2 oil or MIBC.

4. The copper-sulfur selective separation method based on asynchronous flotation-step suppression according to claim 1, characterized in that, The dispersant mentioned in step 2) is sodium hexametaphosphate, water glass, or carboxymethyl cellulose.

5. The copper-sulfur selective separation method based on asynchronous flotation-step suppression according to claim 1, characterized in that, The organic inhibitor mentioned in step 2) is a legume polysaccharide inhibitor, levodopa, diosmin, or sodium dimethyl dithiocarbamate.

6. The copper-sulfur selective separation method based on asynchronous flotation-step suppression according to claim 1, characterized in that, The collector mentioned in step 2) is butyl xanthate, pentyl xanthate, or Z-200.

7. The copper-sulfur selective separation method based on asynchronous flotation-step suppression according to claim 1, characterized in that, The foaming agent mentioned in step 2) is No. 2 oil or MIBC.

8. The copper-sulfur selective separation method based on asynchronous flotation-step suppression according to claim 1, characterized in that, The activator mentioned in step 3) is copper sulfate or lead nitrate.

9. The copper-sulfur selective separation method based on asynchronous flotation-step suppression according to claim 1, characterized in that, The collector mentioned in step 3) is butyl xanthate or pentyl xanthate.

10. The copper-sulfur selective separation method based on asynchronous flotation-step suppression according to claim 1, characterized in that, The foaming agent mentioned in step 3) is No. 2 oil or MIBC.

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