A Combination Inhibitor for Copper-Lead Separation and Its Application

Abstract

This invention discloses a combined inhibitor for copper-lead separation and its application. The combined inhibitor comprises ferric chloride (FeCl3) and 2,5-dimercapto-1,3,4-thiadiazole (DMTD), with a mass ratio of FeCl3 to DMTD of (0.5–4):(2–10). This combined inhibitor is applied to the flotation separation of copper-lead sulfide ores, inhibiting chalcopyrite and resulting in good copper-lead separation with high-grade concentrate. This is of great significance for the efficient recovery and utilization of copper-lead sulfide ores. Furthermore, both FeCl3 and DMTD in the combined inhibitor are non-toxic and pollution-free, avoiding the problems of toxicity and environmental and human health issues associated with traditional inhibitors. This combined inhibitor requires a small dosage, has stable effects, and strong inhibitory ability, showing promising prospects for technological applications.

Description

Technical Field

[0001] This invention relates to a combined inhibitor for copper-lead separation and its application, belonging to the field of mineral processing reagents technology. Background Technology

[0002] Chalcopyrite (CuFeS2) and galena (PbS) are important raw materials for smelting copper and lead, and are mostly found in polymetallic sulfide deposits. In the flotation of copper-lead polymetallic sulfide ores, a common method for copper and lead recovery is to first perform mixed flotation of copper and lead followed by copper-lead separation. However, the flotation separation of chalcopyrite and galena is challenging due to homogenization and their similar floatability. Therefore, after removing surface flotation reagents, the mixed copper-lead concentrate should undergo effective flotation conditioning to reduce the floatability of either chalcopyrite or galena and increase the difference in floatability between the two minerals.

[0003] For copper-lead mixed concentrates with a copper-lead mass ratio greater than 1, based on the flotation principle of "suppressing more and floating less," cyanide was previously commonly used to suppress copper minerals in the concentrate. When the copper-lead mass ratio is less than 1, especially when separating copper from lead concentrate, a "lead suppression and copper flotation" scheme should be adopted. Potassium dichromate (K2Cr2O7) is often used as a depressant for galena.

[0004] However, given the requirements of environmental protection departments and the increasingly "poor, fine-grained, and complex" characteristics of mined ores, the use of toxic and environmentally harmful agents such as cyanide and dichromate is discouraged. Some organic inhibitors, such as sodium pyrophosphate, polysaccharides, carboxymethyl cellulose, and lignin, suffer from low solubility, unstable efficacy, and poor selectivity. Therefore, research on low-cost, green, and efficient inhibitors is of great significance for improving resource utilization and reducing environmental pollution.

[0005] Currently, in existing technologies, single inhibitors are difficult to achieve highly efficient inhibition, while some combined inhibitors are environmentally harmful and have limited inhibitory effects. Therefore, it is necessary to find a highly efficient, non-toxic, and environmentally friendly combined inhibitor to solve the problem of flotation separation of polymetallic copper-lead sulfide ores. Summary of the Invention

[0006] One objective of this invention is to provide a combined inhibitor for the flotation separation of copper-lead sulfide ores, thereby addressing the aforementioned problems. This combined inhibitor selectively inhibits chalcopyrite, achieving copper-lead separation, and requires only a small dosage while maintaining stable efficacy.

[0007] This combined inhibitor comprises ferric chloride (FeCl3) and 2,5-dimercapto-1,3,4-thiadiazole (DMTD), wherein the mass ratio of ferric chloride (FeCl3) to DMTD is (0.5–4):(2–10). This combined inhibitor is used to inhibit chalcopyrite. When the combined inhibitor is added to the slurry, the mass percentage of the ferric chloride (FeCl3) aqueous solution is adjusted to 1%, the mass percentage of the DMTD aqueous solution is adjusted to 5%, and the pH is adjusted to 10 using NaOH.

[0008] The molecular formula of the 2,5-dimercapto-1,3,4-thiadiazole is C2H2N2S3, and its structural formula is as follows:

[0009]

[0010] This combined inhibitor for copper-lead separation is applied in the flotation separation of copper-lead sulfide. After the copper-lead mixed concentrate is slurry prepared, it is subjected to a flotation process of one roughing, two scavenging, and three cleaning to obtain copper concentrate and lead concentrate. The specific steps are as follows:

[0011] After adjusting the copper-lead mixed concentrate to 30-40%, 200-500 g / t activated carbon, 400-1000 g / t combined depressant, 20-40 g / t ethyl yellow, and 10-20 g / t No. 2 oil are added, followed by a lead roughing operation to obtain roughed lead concentrate and roughed lead tailings.

[0012] Add 10-20 g / t of ethyl sulfide and 8-15 g / t of No. 2 oil to the roughing lead tailings for a first lead scavenging operation to obtain the first lead scavenging concentrate and the first lead scavenging tailings. Add 5-10 g / t of ethyl sulfide and 5-10 g / t of No. 2 oil to the first lead scavenging tailings for a second lead scavenging operation to obtain the second lead scavenging concentrate and the second lead scavenging tailings. Return the second lead scavenging concentrate to the first scavenging operation to form a closed loop. The second lead scavenging tailings are the lead tailings.

[0013] A first lead cleaning operation is performed by adding 100–500 g / t of combined depressant to the roughing lead concentrate, yielding a first lead cleaning concentrate and tailings. The tailings from the first lead cleaning operation are mixed with the first lead scavenging concentrate and returned to the lead roughing operation. A second lead cleaning operation is performed by adding 50–200 g / t of combined depressant to the first lead cleaning concentrate, yielding a second lead cleaning concentrate and tailings. The tailings from the second lead cleaning operation are returned to the first lead cleaning operation. The second lead cleaning concentrate is then subjected to a third lead cleaning operation without any reagents, yielding the third lead cleaning concentrate, which is the lead concentrate. The tailings from the third lead cleaning operation are returned to the second lead cleaning operation, forming a closed-loop cycle.

[0014] The technical principle of this invention is as follows:

[0015] The inhibitory mechanism of the combined inhibitor has the following four points: First, FeCl3 promotes the oxidative dissolution of the chalcopyrite surface, eliminating components that cause the chemical composition of the chalcopyrite and galena surfaces to tend towards homogenization. Simultaneously, the dissolved Cu ions undergo strong chelation with DMTD to form a hydrophilic Cu-DMTD complex surface. Second, FeCl3 also promotes the oxidative dissolution of the galena surface, but its effect on its surface chemical composition is not significant; hydrophobic sulfides and ethyl sulfoxide adsorption products exist on its surface. Third, a surface rich in hydrophilic iron hydroxyl oxides, hydroxides, and ferric hydroxysulfate is formed on the chalcopyrite surface, enhancing the hydrophilicity of the chalcopyrite surface, but having little effect on galena. Therefore, it increases the difference in floatability between the two, enabling efficient separation. Fourth, Fe... 3+ The introduction of FeCl3 removes most of the chalcopyrite and cuprous xanthate from the surface of chalcopyrite in the mixed copper-lead concentrate, while exposing new surfaces that allow DMTD to complex on these surfaces, forming hydrophilic Cu(I)-DMTD. Although DMTD can also adsorb on the galena surface, its adsorption is weaker compared to chalcopyrite. Furthermore, in a system where ethyl xanthate is the collector, ethyl xanthate can compete with DMTD for adsorption on the galena surface, leading to the desorption of some DMTD adsorbed on the galena surface, but with little effect on chalcopyrite. Therefore, DMTD can effectively and selectively inhibit chalcopyrite. Thus, the combination of FeCl3 and DMTD, as a chalcopyrite inhibitor, can selectively inhibit chalcopyrite at appropriate dosages, while having minimal impact on the flotation of galena.

[0016] The beneficial effects of this invention are:

[0017] (1) The FeCl3 and DMTD of the present invention are combined in a certain proportion as chalcopyrite inhibitors. Through the synergistic effect between the two agents, the defects of traditional inhibitors such as large dosage, high cost, toxicity and poor selectivity are solved.

[0018] (2) The combined copper inhibitor of the present invention for copper-lead separation is applied to the flotation separation of copper-lead sulfide, with good separation effect and high concentrate grade, which is of great significance for the efficient recovery and utilization of copper-lead sulfide ore.

[0019] (3) Compared with traditional inhibitors, the FeCl3 and DMTD in the combined inhibitor of the present invention are both non-toxic and harmless, avoiding the problems of traditional inhibitors being toxic, environmentally unfriendly and unfriendly to the human body.

[0020] (4) The combined inhibitors of the present invention have small dosage, stable effect, strong inhibitory ability, and good process application prospects. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0023] Example 1: Experimental study on flotation separation of a copper-lead polymetallic sulfide ore in Yunnan Province. The raw ore contained 0.59% Cu and 1.87% Pb. The main minerals were chalcopyrite, galena, sphalerite, and pyrite. The gangue minerals were mainly quartz and calcite.

[0024] In this embodiment, the combined inhibitor is a 5% DMTD solution with pH adjusted to 10 using NaOH, a 1% ferric chloride solution, and the mass ratio of ferric chloride (FeCl3) to DMTD is 4:2.

[0025] The specific steps for the flotation separation of copper-lead sulfide using the combined inhibitors in this embodiment are as follows:

[0026] (1) Grind the raw ore to 75% of the size of -0.074mm, and then obtain copper-lead mixed concentrate and copper-lead mixed tailings through a copper-lead mixed flotation process of one roughing, two scavenging and three cleaning.

[0027] (2) Copper-lead separation flotation: The process is as follows Figure 1 As shown, in the roughing process, the copper-lead mixed concentrate is slurry adjusted to a slurry concentration of 30%. 200 g / t activated carbon, 400 g / t combined inhibitor (i.e., 133.33 g / t DMTD solution and 266.67 g / t ferric chloride solution), 20 g / t ethyl yellow, and 10 g / t No. 2 oil are added to the slurry. After stirring for 3 minutes, a lead roughing operation is carried out, followed by flotation for 3 minutes to obtain roughed lead concentrate and roughed lead tailings.

[0028] (3) Copper-lead separation-scavenging process: Add 10g / t of ethyl yellow and 8g / t of No. 2 oil to the rough lead tailings in step (2), stir for 3 minutes and then carry out the first lead scavenging operation, float for 2 minutes to obtain the first lead scavenging concentrate and the first lead scavenging tailings; add 5g / t of ethyl yellow and 5g / t of No. 2 oil to the first lead scavenging tailings, stir for 3 minutes and then carry out the second lead scavenging operation, float for 2 minutes to obtain the second lead scavenging concentrate and the second lead scavenging tailings. The second lead scavenging concentrate is returned to the first lead scavenging operation to form a closed loop. The second lead scavenging tailings are the lead tailings, which are the final copper concentrate.

[0029] (4) Copper-Lead Separation and Refinement Process: 200 g / t of combined inhibitor (66.67 g / t of DMTD solution and 133.33 g / t of ferric chloride solution) is added to the roughing lead concentrate slurry. After stirring for 3 minutes, the first lead refinement operation is performed. After flotation for 2 minutes, the first refined lead concentrate and tailings are obtained. The tailings are mixed with the first scavenged lead concentrate and returned to the lead roughing operation. 100 g / t of combined inhibitor (33.33 g / t of DMTD solution and 66.67 g / t of ferric chloride solution) is added to the first refined lead concentrate. After stirring for 3 minutes, the second refinement operation is performed. After flotation for 2 minutes, the second refined lead concentrate and tailings are obtained. The tailings are returned to the first refinement operation. The second refined lead concentrate is then subjected to a third refinement operation without any reagents. The third refinement yields the third refined lead concentrate, which is the lead concentrate itself. The tailings are returned to the second refinement operation, forming a closed-loop cycle. The flotation separation effect is shown in Table 1.

[0030] Comparative Example 1: Sodium cyanide was used to suppress chalcopyrite in Comparative Example 1, while other process conditions remained unchanged. The flotation results are shown in Table 1.

[0031] Comparative Example 2: DMTD was used as a chalcopyrite inhibitor in Comparative Example 2, with other process conditions remaining unchanged. The flotation results are shown in Table 1.

[0032] Table 1. Flotation separation results of Example 1 and Comparative Examples 1 and 2

[0033]

[0034] As shown in Table 1, under the condition of minimum reagent dosage, the combined inhibitor improved the recovery rates of copper and lead by 2.09% and 0.6% respectively compared with sodium cyanide, and by 5.54% and 2.85% respectively compared with DMTD alone. The combined inhibitor demonstrated good inhibition performance and efficient copper-lead separation effect on chalcopyrite under this flotation process and reagent regime.

[0035] Example 2: Using a polymetallic sulfide ore in Sichuan as the ore sample, the original ore had a Cu grade of 0.35% and a Pb grade of 0.76%. Copper mainly existed in the form of chalcopyrite, and lead mainly existed in the form of galena.

[0036] In this embodiment, the combined inhibitor concentration is 5% DMTD solution with pH adjusted to 10 using NaOH, 1% ferric chloride solution, and the mass ratio of ferric chloride (FeCl3) to DMTD is 0.5:10.

[0037] After the ore sample undergoes copper-lead mixed flotation, a copper-lead mixed concentrate is obtained. The copper-lead mixed concentrate is then slurry-adjusted and subjected to a flotation process consisting of one roughing, two scavenging, and two cleaning stages to obtain copper concentrate and lead concentrate. The specific steps are as follows:

[0038] (1) Copper-lead separation flotation-roughing process: The copper-lead mixed concentrate is adjusted to a pulp concentration of 40%. 500g / t activated carbon, 1000g / t combined inhibitor (i.e., 952.38g / t DMTD solution and 47.62g / t ferric chloride solution), 40g / t ethyl yellow, and 20g / t No. 2 oil are added to the pulp. After stirring for 3 minutes, a lead roughing operation is carried out for 3 minutes to obtain roughed lead concentrate and roughed lead tailings.

[0039] (2) Scavenging process: Add 20g / t of ethyl yellow and 15g / t of No. 2 oil to the rough lead tailings in step (1), stir for 3 minutes and then carry out the first lead scavenging operation, float for 2 minutes to obtain the first lead scavenging concentrate and the first lead scavenging tailings; add 10g / t of ethyl yellow and 10g / t of No. 2 oil to the first lead scavenging tailings, stir for 3 minutes and then carry out the second lead scavenging operation, float for 2 minutes to obtain the second lead scavenging concentrate and the second lead scavenging tailings, return the second lead scavenging concentrate to the first lead scavenging operation to form a closed loop, and the second lead scavenging tailings are the lead tailings, which are the final copper concentrate;

[0040] (3) Refinement process: 500 g / t of combined inhibitor (476.19 g / t of DMTD solution and 23.81 g / t of ferric chloride solution) is added to the slurry. After stirring for 3 minutes, the first lead refinement operation is performed. After flotation for 2 minutes, the first lead refinement concentrate and the first lead refinement tailings are obtained. The first lead refinement tailings are mixed with the first lead scavenging concentrate and returned to the lead roughing operation. 200 g / t of combined inhibitor (190.48 g / t of DMTD solution and 9.52 g / t of ferric chloride solution) is added to the first lead refinement concentrate. After stirring for 3 minutes, the second lead refinement operation is performed. After flotation for 2 minutes, the second lead refinement concentrate and the second lead refinement tailings are obtained. The second lead refinement tailings are returned to the first lead refinement operation. The second lead refinement concentrate is subjected to a third lead refinement operation without adding any reagents. The third lead refinement concentrate is the lead concentrate. The third lead refinement tailings are returned to the second lead refinement operation, forming a closed-loop cycle. The flotation experiment results are shown in Table 2.

[0041] Comparative Example 3: Sodium cyanide was used to suppress chalcopyrite in Comparative Example 3, while other process conditions remained unchanged. The flotation results are shown in Table 2.

[0042] Comparative Example 4: DMTD was used as a chalcopyrite inhibitor in Comparative Example 4, with other process conditions remaining unchanged. The flotation results are shown in Table 2.

[0043] Table 2. Flotation separation results of Example 2 and Comparative Examples 3 and 4

[0044]

[0045] Under the same experimental conditions, the combined inhibitor was more effective than DMTD alone in reducing copper in lead concentrate, and had a better inhibitory effect on chalcopyrite. Compared with sodium cyanide, it increased copper recovery by 1.78% and lead recovery by 0.72%.

[0046] Example 3: A copper-lead-zinc sulfide ore from Yunnan Province was used as the ore sample. The original ore had a Cu grade of 0.5% and a Pb grade of 1.32%.

[0047] In this embodiment, the combined inhibitor is a 5% DMTD solution with pH adjusted to 10 using NaOH, and a 1% ferric chloride solution with a ferric chloride FeCl3 to DMTD mass ratio of 2:3.

[0048] After the ore sample undergoes copper-lead mixed flotation, a copper-lead mixed concentrate is obtained. The copper-lead mixed concentrate is then slurry-adjusted and subjected to a flotation process of one roughing, two scavenging, and three cleaning stages to obtain copper concentrate and lead concentrate. The specific steps are as follows:

[0049] (1) Copper-lead separation flotation-roughing process: The copper-lead mixed concentrate is adjusted to a pulp concentration of 35%. 350g / t activated carbon, 700g / t combined inhibitor (i.e., 420g / t DMTD solution and 280g / t ferric chloride solution), 30g / t ethyl yellow, and 15g / t No. 2 oil are added to the pulp. After stirring for 3 minutes, a lead roughing operation is carried out for 3 minutes to obtain roughed lead concentrate and roughed lead tailings.

[0050] (2) Scavenging process: Add 15g / t of ethyl yellow and 10g / t of No. 2 oil to the rough lead tailings in step (1), stir for 3 minutes and then carry out the first lead scavenging operation, float for 2 minutes to obtain the first lead scavenging concentrate and the first lead scavenging tailings; add 8g / t of ethyl yellow and 8g / t of No. 2 oil to the first lead scavenging tailings, stir for 3 minutes and then carry out the second lead scavenging operation, float for 2 minutes to obtain the second lead scavenging concentrate and the second lead scavenging tailings, return the second lead scavenging concentrate to the first lead scavenging operation to form a closed loop, and the second lead scavenging tailings are the lead tailings, which are the final copper concentrate;

[0051] (3) Refinement process: 350 g / t of combined inhibitors (i.e., 210 g / t of DMTD solution and 140 g / t of ferric chloride solution) are added to the slurry. After stirring for 3 minutes, the first lead refinement operation is performed. After flotation for 2 minutes, the first lead refinement concentrate and the first lead refinement tailings are obtained. The first lead refinement tailings are mixed with the first lead scavenging concentrate and returned to the lead roughing operation. 150 g / t of combined inhibitors (i.e., 100 g / t of DMTD solution and 50 g / t of ferric chloride solution) are added to the first lead refinement concentrate. After stirring for 3 minutes, the second lead refinement operation is performed. After flotation for 2 minutes, the second lead refinement concentrate and the second lead refinement tailings are obtained. The second lead refinement tailings are then used in the first lead refinement operation. The second lead refinement concentrate is used in the third lead refinement operation without adding any reagents. The third lead refinement concentrate is obtained as the lead concentrate. The third lead refinement tailings are returned to the second lead refinement operation, forming a closed-loop cycle. The flotation experiment results are shown in Table 3.

[0052] Comparative Example 5: Comparative Example 5 used sodium cyanide to suppress chalcopyrite, while keeping other process conditions unchanged. The flotation results are shown in Table 3.

[0053] Comparative Example 6: DMTD was used to suppress chalcopyrite in Comparative Example 6, while other process conditions remained unchanged. The flotation results are shown in Table 3.

[0054] Table 3. Flotation separation results of Example 3 and Comparative Examples 5 and 6

[0055]

[0056] Table 3 shows that the combined inhibitor has a good inhibitory effect on chalcopyrite, enabling efficient copper-lead separation. Furthermore, compared to sodium cyanide, the combined inhibitor is widely available, non-toxic, pollution-free, and poses less environmental pressure, making it more suitable for use in industrial production.

[0057] In summary, the combined inhibitor (ferric chloride + DMTD) exhibits significant effects in inhibiting copper and lead flotation. While sodium cyanide can also effectively inhibit chalcopyrite, it suffers from drawbacks such as high toxicity and significant environmental impact. DMTD, as a low-molecular-weight organic compound, is widely available, has less environmental impact, requires only a small dosage, and is a novel, environmentally friendly, and highly efficient chalcopyrite inhibitor. The combined inhibitor of this invention is stable, exhibits good selective inhibition, requires a small dosage, is safe to use, has strong adaptability, and has broad application prospects.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A combined inhibitor for copper-lead separation, characterized in that, The combined inhibitor comprises ferric chloride (FeCl3) and 2,5-dimercapto-1,3,4-thiadiazole (DMTD), wherein the molecular formula of 2,5-dimercapto-1,3,4-thiadiazole is C2H2N2S3, and its structural formula is as follows: ； The mass ratio of ferric chloride (FeCl3) to DMTD is (0.5~4):(2~10). The combined inhibitor is used to inhibit chalcopyrite. When the combined inhibitor is added to the slurry, the mass percentage of ferric chloride (FeCl3) aqueous solution is adjusted to 1%, the mass percentage of DMTD aqueous solution is adjusted to 5%, and the pH is adjusted to 10 using NaOH.

2. The combined inhibitor for copper-lead separation as described in claim 1 is applied in the flotation separation of copper-lead sulfide, characterized in that, After the copper-lead mixed concentrate is slurryed, it undergoes a flotation process of one roughing, two scavenging, and three cleaning stages to obtain lead tailings and lead concentrate with high copper content. The specific steps are as follows: After adjusting the copper-lead mixed concentrate to 30-40%, 200-500 g / t activated carbon, 400-1000 g / t combined depressant, 20-40 g / t ethyl yellow, and 10-20 g / t No. 2 oil are added, and a lead roughing operation is carried out to obtain rough lead concentrate and rough lead tailings. Add 10-20 g / t of ethyl yellow and 8-15 g / t of No. 2 oil to the roughing lead tailings for the first lead scavenging operation to obtain the first lead scavenging concentrate and the first lead scavenging tailings; add 5-10 g / t of ethyl yellow and 5-10 g / t of No. 2 oil to the first lead scavenging tailings for the second lead scavenging operation to obtain the second lead scavenging concentrate and the second lead scavenging tailings; return the second lead scavenging concentrate to the first scavenging operation to form a closed loop, and the second lead scavenging tailings are the lead tailings; A first lead cleaning operation is performed by adding 100-500 g / t of combined depressant to the roughing lead concentrate, yielding a first lead cleaning concentrate and a first lead cleaning tailings. The first lead cleaning tailings are mixed with the first lead scavenging concentrate and returned to the lead roughing operation. A second lead cleaning operation is performed by adding 50-200 g / t of combined depressant to the first lead cleaning concentrate, yielding a second lead cleaning concentrate and a second lead cleaning tailings. The second lead cleaning tailings are returned to the first lead cleaning operation. The second lead cleaning concentrate is then subjected to a third lead cleaning operation without adding any reagents, yielding the third lead cleaning concentrate, which is the lead concentrate. The third lead cleaning tailings are returned to the second lead cleaning operation, forming a closed-loop cycle.

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