Environment-friendly copper-molybdenum separation depressant, preparation method and application thereof

Abstract

This invention relates to the field of mineral processing technology, specifically to an environmentally friendly copper-molybdenum separation inhibitor, its preparation method, and its application. The method includes: mixing starch and formamide, stirring at room temperature, cooling in an ice-water bath at -5°C, slowly adding chlorosulfonic acid at this temperature to initiate a sulfonation reaction, neutralizing to pH 7-8 with sodium hydroxide solution after the reaction, adding anhydrous methanol to precipitate the product, and washing and drying to obtain the sulfonated anionic starch polymer DGSS. The inhibitor is applied to the flotation separation of copper-molybdenum mixed concentrates, combined with a closed-circuit process of one roughing, one scavenging, and four cleaning stages, employing a gradient reagent reduction and staged kerosene replenishment system from roughing to cleaning. This allows for selective inhibition of copper sulfide minerals such as chalcopyrite at extremely low dosages, with minimal impact on the floatability of molybdenite. It completely avoids the use of toxic substances such as cyanide, Knox reagent, or sodium sulfide, exhibiting good selectivity, low reagent consumption, environmental friendliness, and a simple preparation process that is easy to industrialize.

Description

Technical Field

[0001] This invention relates to the field of mineral processing technology, specifically to an environmentally friendly copper-molybdenum separation inhibitor, its preparation method, and its application. Background Technology

[0002] Copper-molybdenum separation is an important topic in mineral processing. Molybdenite (MoS2) often occurs in close association with copper sulfide minerals such as chalcopyrite (CuFeS2). Due to their similar natural floatability, traditional flotation processes struggle to achieve efficient separation of copper and molybdenum. Currently, the industrial practice commonly employs a "copper-suppressing, molybdenum-floating" process, which involves adding inhibitors to suppress the flotation of copper-bearing minerals such as chalcopyrite, thereby achieving selective flotation enrichment of molybdenite.

[0003] Traditional copper-molybdenum separation inhibitors mainly include inorganic inhibitors (such as sulfur-containing compounds, cyanides, Knox reagents, etc.) and organic inhibitors (such as mercapto compounds, thioureas, and thiocarbonates, etc.). Among them, sodium sulfide (Na2S) and its combination agents have become the most widely used type of inhibitor due to their significant inhibitory effect and wide applicability. However, traditional inhibitors have many problems in practical applications: (1) Great environmental hazards. For example, cyanides and Knox reagents are highly toxic and pose a serious threat to the ecological environment and the health of operators. Sodium sulfide is easy to decompose and release toxic hydrogen sulfide gas (H2S) under acidic or high temperature conditions, and its large-scale use can easily cause water pollution. (2) Large reagent consumption and high production costs. For example, the consumption of sodium sulfide is usually tens of kilograms / ton of raw ore, which significantly increases the reagent cost of the beneficiation plant. (3) Poor selectivity and serious metal intermingling in the concentrate product. Traditional inhibitors, while inhibiting chalcopyrite, also exhibit non-selective adsorption or physical entrainment of molybdenite, exacerbating the cross-encapsulation of metals in the concentrate. With increasingly stringent environmental protection requirements and the deepening of the green mining concept, developing efficient, low-toxicity, easily degradable, highly selective, and cost-effective environmentally friendly copper-molybdenum separation inhibitors has become an urgent need for technological upgrading in the mineral processing field. In recent years, researchers have attempted to utilize natural polymers, small-molecule organic acids, and their complex combinations as novel inhibitors; however, these approaches still have shortcomings in terms of inhibitory effect and adaptability, making it difficult to completely replace traditional inhibitors.

[0004] In summary, there is an urgent need in this field for an environmentally friendly method for preparing copper-molybdenum separation inhibitors and their applications, in order to overcome the barriers of existing technologies. This is of great practical significance for the efficient development and utilization of copper-molybdenum ore resources. Summary of the Invention

[0005] The purpose of this invention is to provide an environmentally friendly copper-molybdenum separation inhibitor, its preparation method, and its application. The inhibitor is prepared by low-temperature sulfonation reaction of starch with formamide and chlorosulfonic acid, and is used for flotation separation of copper-molybdenum mixed concentrates. It has good selectivity, low dosage, and is environmentally friendly.

[0006] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution: A method for preparing an environmentally friendly copper-molybdenum separation inhibitor involves mixing starch and formamide, stirring at room temperature, and then cooling the mixture to -5°C in an ice-water bath. Chlorosulfonic acid is then added dropwise to the resulting mixture while maintaining the -5°C temperature for sulfonation. After the reaction is complete, sodium hydroxide solution is added to neutralize the mixture to pH 7-8. Anhydrous methanol is then added to the neutralized system to precipitate the product, which is collected by centrifugation. The precipitate is washed with anhydrous methanol and dried at 40-60°C for 24 h to obtain the environmentally friendly copper-molybdenum separation inhibitor.

[0007] Furthermore, the ratio of starch to formamide is 2-5 g: 20-50 mL, the amount of chlorosulfonic acid added is 5-12.5 mL, and the adding time is 60-90 min.

[0008] Furthermore, the stirring time at room temperature is 30-60 minutes, and the washing is performed 3-5 times.

[0009] Furthermore, the stirring speed during the sulfonation reaction and neutralization process is 600~1000 r / min.

[0010] Furthermore, the volume ratio of the anhydrous methanol to the formamide is 3~5:1.

[0011] Furthermore, the starch is corn starch, wheat starch, rice starch, potato starch, or cassava starch.

[0012] On the other hand, the present invention proposes an environmentally friendly copper-molybdenum separation inhibitor, which is prepared by the above-mentioned preparation method.

[0013] On the other hand, the present invention proposes the application of the above-mentioned environmentally friendly copper-molybdenum separation inhibitor in the flotation separation of copper-molybdenum mixed concentrate, including the following steps: S1: Grind the copper-molybdenum mixed concentrate to a thickness of -0.038 mm, with 80%~90% of the concentrate being 0.038 mm, and adjust the slurry concentration to 35%~40%. S2: Add sodium hydroxide to the slurry obtained in S1 to adjust the pH to 11.5~12.5, and then add the inhibitor, kerosene and methyl isobutyl methanol in sequence for a roughing process to obtain roughing concentrate and roughing tailings; wherein the amount of inhibitor is 1500~2500 g / t, the amount of kerosene is 100~300 g / t, and the amount of methyl isobutyl methanol is 30~100 g / t; S3: The inhibitor, kerosene, and methyl isobutyl methanol are added sequentially to the roughing tailings obtained in S2 for a single scavenging process to obtain scavenged concentrate and copper concentrate. The scavenged concentrate is then returned to the roughing operation in S2. The amount of inhibitor used is 150-250 g / t, the amount of kerosene used is 50-100 g / t, and the amount of methyl isobutyl methanol used is 15-50 g / t. S4: Perform four cleaning operations on the rough concentrate obtained from S2, specifically including: S4.1: In the first fine selection, 300~500 g / t of the inhibitor is added to obtain fine concentrate and fine tailings. The fine tailings are returned to the roughing operation in S2. S4.2: Add 150-250 g / t of the inhibitor and 50-100 g / t of kerosene to the refined concentrate obtained in S4.1 for a second refinement to obtain refined concentrate and refined tailings. Return the refined tailings to S4.1. S4.3: Add 50-70 g / t of the inhibitor to the refined concentrate obtained in S4.2 for a third refining process to obtain refined concentrate and refined tailings. Return the refined tailings to S4.2. S4.4: Add 20-40 g / t of the inhibitor and 20-40 g / t of kerosene to the refined concentrate obtained in S4.3 for a fourth refinement to obtain molybdenum concentrate and refined tailings. Return the refined tailings to S4.3 to form a closed loop.

[0014] Furthermore, the amount of the inhibitor mentioned in S2 is 2000~2500 g / t, the amount of kerosene is 200~300 g / t, and the amount of methyl isobutyl methanol is 80~100 g / t.

[0015] Furthermore, the amount of the inhibitor mentioned in S3 is 200~250 g / t, the amount of kerosene is 80~100 g / t, and the amount of methyl isobutyl methanol is 30~50 g / t.

[0016] It should be understood that the primary hydroxyl group at C6 of starch has the highest activity and preferentially undergoes esterification. Based on the solubilizing and catalytic effects of formamide, sulfonic acid groups (-SO3H) are grafted onto the network structure of starch via esterification to synthesize a sulfonated anionic starch polymer (DGSS). The polymer has the following characteristics: First, DGSS is rich in sulfonic acid and hydroxyl groups, exhibiting a strong affinity for copper and iron active sites, and can selectively adsorb onto the surface of copper sulfide minerals, forming a stable capping of hydrophilic species, while having little effect on molybdenite. Second, the network structure of starch promotes the bridging adsorption of DGSS on mineral particles, effectively reducing the cost of reagents for inhibiting copper sulfide minerals. The grafted sulfonic acid groups point towards the pulp and exhibit strong electronegativity, enhancing the solubility of starch. Third, the preparation method of this polymer is simple and easy to implement on a large scale. The specific chemical reaction equation is as follows: The beneficial effects of this invention are: This invention utilizes a sulfonation process involving the slow, dropwise addition of chlorosulfonic acid at -5°C to covalently graft sulfonic acid groups onto the starch molecular backbone, yielding the anionic starch polymer DGSS. The densely distributed sulfonate and hydroxyl groups on the polymer molecular chain exhibit strong chemical affinity for the copper and iron active sites on the chalcopyrite surface. This allows for multi-point anchoring and adsorption to form a dense, hydrophilic hydration film on the chalcopyrite surface, while showing extremely weak adsorption on the layered hydrophobic surface of molybdenite. Thus, highly selective separation of chalcopyrite and molybdenite is achieved without the use of toxic substances such as cyanide, Knox reagent, or sodium sulfide. Example results show that using DGSS achieves a molybdenum concentrate grade of 45.85%-51.23%, while maintaining a copper recovery rate of over 99.45% in the copper concentrate, demonstrating a selective inhibition capability that surpasses traditional highly toxic inhibitor systems.

[0017] This invention utilizes the synergistic mechanism of polymeric multi-point anchoring and bridging flocculation of DGSS to achieve complete suppression of chalcopyrite with a roughing dosage of only 1500-2500 g / t and a cumulative dosage of approximately 3000-3500 g / t throughout the entire process. Compared to the comparative example where the cumulative dosage of sodium sulfide exceeded 17 kg / t, the unit mass suppression efficiency of DGSS is increased by 5-8 times, and the reagent consumption is reduced to one-fifth to one-tenth of that of the sodium sulfide system. This difference directly translates into a significant reduction in the cost of mineral processing reagents. Furthermore, due to the low dosage and biodegradability of DGSS, the tailings water treatment load and environmental compliance costs are also significantly reduced.

[0018] This invention designs a closed-circuit flotation process with gradient reagent reduction and selective collector supplementation, specifically addressing the suppression characteristics of DGSS. In the roughing stage, a high dose of DGSS is used to establish an initial suppression environment. In the scavenging stage, the dosage is reduced to 150-250 g / t to suppress residual copper minerals. During the four cleaning stages, the DGSS dosage is gradually reduced from 300-500 g / t to 20-40 g / t, with kerosene added in appropriate amounts during the second and fourth cleaning operations. This ensures that the suppression intensity decreases synchronously with the number of cleaning operations, preventing the loss of molybdenite due to excessive suppression. Furthermore, the staged addition of kerosene activates the molybdenite surface in a timely manner, thus achieving efficient molybdenum recovery while ensuring effective suppression of copper minerals throughout the process.

[0019] The DGSS preparation method provided by this invention can be implemented using a conventional enamel-lined reactor. Starch and formamide are stirred and swollen at room temperature. Then, chlorosulfonic acid is added dropwise at a uniform rate over 60-90 minutes in an ice-water bath at -5°C. This low-temperature, slow-dropping process effectively controls the exothermic rate of the sulfonation reaction, preventing starch carbonization, cross-linking, or glycosidic bond breakage. Subsequently, sodium hydroxide is used to neutralize to pH 7-8 to convert the sulfonic acid groups to sodium sulfonate to enhance water solubility. Finally, anhydrous methanol is added at 3-5 times the volume of formamide to precipitate the product. After repeated washing to remove impurities, the product is dried at 40-60°C to obtain the pure product. This method does not involve high temperature and pressure, requires no inert gas protection, and does not use highly toxic or explosive reagents. The reaction conditions are mild, the operating window is wide, and batch reproducibility is good, making it directly feasible for industrial scale-up.

[0020] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments 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.

[0022] Figure 1 This is a flowchart of the flotation separation process for copper-molybdenum mixed concentrate according to the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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. Example 1

[0024] The preparation method of the inhibitor in this embodiment is as follows: (1) Weigh 2 g of starch and 20 mL of formamide into a reaction flask, stir at room temperature for 30 min at a stirring speed of 600 r / min, and after stirring, place the reaction flask in an ice-water bath and cool to -5 ℃. (2) Measure 5 mL of chlorosulfonic acid and slowly add it to the starch-formamide mixture in step (1) through a constant pressure dropping funnel. The dropping time is 60 min. During the dropping process, turn on the stirrer at a speed of 600 r / min and maintain the temperature at -5 ℃. (3) Slowly add 1 mol / L sodium hydroxide solution to step (2), and use pH test paper to detect the pH value of the mixture until the pH is adjusted to 7. During the addition process, continue to cool in an ice bath and stir at a speed of 600 r / min. (4) Add 60 mL of anhydrous methanol to step (3) (the volume ratio of anhydrous methanol to formamide is 3:1). After the reaction is complete, collect the precipitate by centrifugation. (5) Wash the precipitate from step (4) three times with anhydrous methanol; (6) The precipitate from step (5) is dried at 40 °C for 24 h to obtain the copper-molybdenum separation inhibitor DGSS of the present invention.

[0025] The inhibitor prepared in this embodiment was applied to the flotation separation of a copper-molybdenum mixed concentrate in Yunnan Province. The copper-molybdenum mixed concentrate had a Cu grade of 19.25% and a Mo grade of 0.42%. The main copper sulfide mineral was chalcopyrite, and the main molybdenum mineral was molybdenite. The specific steps for copper-molybdenum separation are as follows: (1) Grinding: The copper-molybdenum mixed concentrate was ground, and the grinding fineness was controlled to be -0.038 mm with a proportion of 80%, and the pulp concentration was adjusted to 35%; (2) Copper-molybdenum separation roughing: Sodium hydroxide is added to the slurry described in step (1) to control the pH of the slurry to 11.5. Then, DGSS 1500 g / t inhibitor, kerosene 100 g / t collector and MIBC 30 g / t frother are added in sequence to carry out one copper-molybdenum separation roughing to obtain roughing concentrate and roughing tailings. (3) Copper-molybdenum separation and scavenging: Add 150 g / t of inhibitor DGSS, 50 g / t of collector kerosene and 15 g / t of frother MIBC to the roughing tailings in step (2) in sequence to carry out one copper-molybdenum separation and scavenging to obtain scavenged concentrate and copper concentrate, wherein the scavenged concentrate is returned to the copper-molybdenum separation roughing. (4) Copper-molybdenum separation and refining: The rough concentrate described in step (2) is subjected to four copper-molybdenum separation and refining processes. During refining I, 300 g / t of inhibitor DGSS is added to obtain refined concentrate I and refined middlings I, wherein the refined middlings I are returned to the copper-molybdenum separation rougher; refined concentrate I is subjected to refining II by adding 150 g / t of inhibitor DGSS and 50 g / t of collector kerosene to refined concentrate I, to obtain refined concentrate II and refined middlings II, wherein the refined middlings II are returned to copper-molybdenum separation refining I; refined concentrate II is subjected to refining III by adding 50 g / t of inhibitor DGSS to refined concentrate II, to obtain refined concentrate III and refined middlings III, wherein the refined middlings III are returned to copper-molybdenum separation refining II; refined concentrate III is subjected to refining IV by adding 20 g / t of inhibitor DGSS and 20 g / t of collector kerosene to refined concentrate III, to obtain molybdenum concentrate and refined middlings IV, wherein the refined middlings IV are returned to copper-molybdenum separation refining III, forming a closed-loop cycle.

[0026] Experimental results: Molybdenum concentrate grade 45.85%, molybdenum recovery rate 81.42%; copper concentrate grade 20.13%, copper recovery rate 99.45%. Example 2

[0027] The preparation method of the inhibitor in this embodiment is as follows: Weigh 3 g of starch and 30 mL of formamide into a reaction flask, stir at room temperature for 40 min at a stirring speed of 800 r / min, and after stirring, place the reaction flask in an ice-water bath and cool to -5℃. (2) Measure 8 mL of chlorosulfonic acid and slowly add it to the starch-formamide mixture in step (1) through a constant pressure dropping funnel. The dropping time is 80 min. During the dropping process, turn on the stirrer at a speed of 800 r / min and maintain the temperature at -5 ℃. (3) Slowly add 1 mol / L sodium hydroxide solution to step (2), and use pH test paper to test the pH value of the mixture until the pH is adjusted to 7.8. During the addition process, continue to cool in an ice bath and stir at a speed of 800 r / min. (4) Add 120 mL of anhydrous methanol to step (3) (the volume ratio of anhydrous methanol to formamide is 4:1). After the reaction is complete, collect the precipitate by centrifugation. (5) Wash the precipitate from step (4) repeatedly with anhydrous methanol 4 times; (6) The precipitate from step (5) is dried at 50 °C for 24 h to obtain the copper-molybdenum separation inhibitor DGSS of the present invention.

[0028] The inhibitor prepared in this embodiment was applied to the flotation separation of a copper-molybdenum mixed concentrate in Yunnan Province. The copper-molybdenum mixed concentrate contained 20.52% Cu and 0.75% Mo. The main copper sulfide mineral was chalcopyrite, with a small amount of chalcocite, and the main molybdenum mineral was molybdenite. The specific steps for copper-molybdenum separation are as follows: (1) Grinding: The copper-molybdenum mixed concentrate was ground, and the grinding fineness was controlled to be -0.038 mm, accounting for about 85%, and the pulp concentration was adjusted to 35%; (2) Copper-molybdenum separation roughing: Sodium hydroxide is added to the slurry described in step (1) to control the pH of the slurry to 11.8. Then, 2000 g / t of inhibitor DGSS, 200 g / t of collector kerosene and 80 g / t of frother methyl isobutyl methanol (MIBC) are added in sequence to carry out one copper-molybdenum separation roughing to obtain roughing concentrate and roughing tailings. (3) Copper-molybdenum separation and scavenging: Add 200 g / t of inhibitor DGSS, 80 g / t of collector kerosene and 30 g / t of frother MIBC to the roughing tailings in step (2) in sequence to carry out one copper-molybdenum separation and scavenging to obtain scavenged concentrate and copper concentrate, wherein the scavenged concentrate is returned to the copper-molybdenum separation roughing. (4) Copper-molybdenum separation and refining: The rough concentrate described in step (2) is subjected to four copper-molybdenum separation and refining processes. During refining I, 400 g / t of inhibitor DGSS is added to obtain refined concentrate I and refined middlings I, wherein the refined middlings I are returned to the copper-molybdenum separation rougher; refined concentrate I is subjected to refining II by adding 200 g / t of inhibitor DGSS and 80 g / t of collector kerosene to refined concentrate I, to obtain refined concentrate II and refined middlings II, wherein the refined middlings II are returned to copper-molybdenum separation refining I; refined concentrate II is subjected to refining III by adding 60 g / t of inhibitor DGSS to refined concentrate II, to obtain refined concentrate III and refined middlings III, wherein the refined middlings III are returned to copper-molybdenum separation refining II; refined concentrate III is subjected to refining IV by adding 30 g / t of inhibitor DGSS and 30 g / t of collector kerosene to refined concentrate III, to obtain molybdenum concentrate and refined middlings IV, wherein the refined middlings IV are returned to copper-molybdenum separation refining III, forming a closed-loop cycle.

[0029] Experimental results: Molybdenum concentrate grade 46.72%, molybdenum recovery rate 82.53%; copper concentrate grade 21.32%, copper recovery rate 99.75%. Example 3

[0030] The preparation method of the inhibitor in this embodiment is as follows: (1) Weigh 5 g of starch and 50 mL of formamide into a reaction flask, stir at room temperature for 90 min at a stirring speed of 1000 r / min, and after stirring, place the reaction flask in an ice-water bath and cool to -5℃. (2) Measure 12.5 mL of chlorosulfonic acid and slowly add it to the starch-formamide mixture in step (1) through a constant pressure dropping funnel. The dropping time is 90 min. During the dropping process, turn on the stirrer at a speed of 1000 r / min and maintain the temperature at -5℃. (3) Slowly add 1 mol / L sodium hydroxide solution to step (2), and use pH test paper to detect the pH value of the mixture until the pH is adjusted to 8. During the addition process, continue to cool in an ice bath and stir at a speed of 1000 r / min. (4) Add 250 mL of anhydrous methanol to step (3) (the volume ratio of anhydrous methanol to formamide is 5:1). After the reaction is complete, collect the precipitate by centrifugation. (5) Wash the precipitate from step (4) repeatedly with anhydrous methanol 5 times; (6) The precipitate from step (5) is dried at 60 °C for 24 h to obtain the copper-molybdenum separation inhibitor DGSS of the present invention.

[0031] The inhibitor prepared in this embodiment was applied to the flotation separation of a copper-molybdenum mixed concentrate in Yunnan Province. The copper-molybdenum mixed concentrate had a Cu grade of 21.15% and a Mo grade of 1.45%. The main copper sulfide mineral was chalcopyrite, and the main molybdenum mineral was molybdenite. The specific steps for copper-molybdenum separation are as follows: (1) Grinding: The copper-molybdenum mixed concentrate was ground, and the grinding fineness was controlled to be -0.038 mm, accounting for about 90%, and the pulp concentration was adjusted to 40%; (2) Copper-molybdenum separation roughing: Sodium hydroxide is added to the slurry described in step (1) to control the pH of the slurry to 12.5. Then, DGSS 2500 g / t inhibitor, kerosene 300 g / t collector and MIBC 100 g / t frother are added in sequence to carry out one copper-molybdenum separation roughing to obtain roughing concentrate and roughing tailings. (3) Copper-molybdenum separation and scavenging: Add 250 g / t of inhibitor DGSS, 100 g / t of collector kerosene and 50 g / t of frother MIBC to the roughing tailings in step (2) in sequence to carry out one copper-molybdenum separation and scavenging to obtain scavenged concentrate and copper concentrate, wherein the scavenged concentrate is returned to the copper-molybdenum separation roughing. (4) Copper-molybdenum separation and refining: The rough concentrate described in step (2) is subjected to four copper-molybdenum separation and refining processes. During refining I, 500 g / t of inhibitor DGSS is added to obtain refined concentrate I and refined middlings I, wherein the refined middlings I are returned to the copper-molybdenum separation rougher; refined concentrate I is subjected to refining II by adding 250 g / t of inhibitor DGSS and 100 g / t of collector kerosene to refined concentrate I, to obtain refined concentrate II and refined middlings II, wherein the refined middlings II are returned to copper-molybdenum separation refining I; refined concentrate II is subjected to refining III by adding 70 g / t of inhibitor DGSS to refined concentrate II, to obtain refined concentrate III and refined middlings III, wherein the refined middlings III are returned to copper-molybdenum separation refining II; refined concentrate III is subjected to refining IV by adding 40 g / t of inhibitor DGSS and 40 g / t of collector kerosene to refined concentrate III, to obtain molybdenum concentrate and refined middlings IV, wherein the refined middlings IV are returned to copper-molybdenum separation refining III, forming a closed-loop cycle.

[0032] Experimental results: Molybdenum concentrate grade 51.23%, molybdenum recovery rate 84.26%; copper concentrate grade 22.02%, copper recovery rate 99.94%.

[0033] Comparative Example 1 The steps for copper-molybdenum flotation separation are the same as in Example 1, except that conventional sodium sulfide is used instead of the inhibitor DGSS. The amounts of sodium sulfide used in roughing, scavenging, cleaning I, cleaning II, cleaning III, and cleaning IV are 15 kg / t, 1.5 kg / t, 1 kg / t, 800 g / t, 600 g / t, and 400 g / t, respectively.

[0034] Experimental results: Molybdenum concentrate grade 44.08%, molybdenum recovery rate 81.53%; copper concentrate grade 20.23%, copper recovery rate 98.35%.

[0035] Comparative Example 2 The steps for copper-molybdenum flotation separation are the same as in Example 2, except that conventional sodium sulfide and sodium thioglycolate are used as a combined inhibitor (the mass ratio of sodium sulfide to sodium thioglycolate is 3:1) instead of the inhibitor DGSS. The amounts of the combined inhibitor used in roughing, scavenging, cleaning I, cleaning II, cleaning III and cleaning IV are 10 kg / t, 1 kg / t, 800 g / t, 600 g / t, 400 g / t and 200 g / t, respectively.

[0036] Experimental results: Molybdenum concentrate grade 44.26%, molybdenum recovery rate 82.82%; copper concentrate grade 21.42%, copper recovery rate 97.85%.

[0037] Comparative Example 3 The steps for copper-molybdenum flotation separation are the same as in Example 3, except that the conventional sodium sulfide and L-cysteine ​​combined inhibitor (sodium sulfide to L-cysteine ​​mass ratio of 8:1) is used instead of the inhibitor DGSS. The amounts of the combined inhibitor used in roughing, scavenging, cleaning I, cleaning II, cleaning III and cleaning IV are 10 kg / t, 1 kg / t, 800 g / t, 600 g / t, 400 g / t and 200 g / t, respectively.

[0038] Experimental results: Molybdenum concentrate grade 48.26%, molybdenum recovery rate 84.52%; copper concentrate grade 22.12%, copper recovery rate 97.05%. The results of Examples 1-3 above demonstrate that the preparation method and application of the environmentally friendly copper-molybdenum separation inhibitor disclosed in this invention have good adaptability to the separation of copper-molybdenum mixed concentrates. The results of Comparative Examples 1-3 show that the inhibitor DGSS of this invention can selectively inhibit copper sulfide minerals at low dosages, improving the flotation separation effect between copper sulfide minerals and molybdenite. Compared with conventional separation indicators using sodium sulfide, a combination of sodium sulfide and sodium thioglycolate, or a combination of sodium sulfide and L-cysteine ​​as inhibitors, the molybdenum concentrate grade is increased by 1-3%, and the copper concentrate recovery rate is increased by 1-2%.

[0039] In summary, this invention proposes an environmentally friendly copper-molybdenum separation inhibitor, its preparation method, and its application. The inhibitor is prepared by the following method: starch and formamide are mixed, stirred at room temperature, and then cooled in an ice-water bath at -5°C. Chlorosulfonic acid is slowly added dropwise at this temperature to carry out a sulfonation reaction. After the reaction is complete, the mixture is neutralized to pH 7-8 with sodium hydroxide solution, and then anhydrous methanol is added to precipitate the product. After washing and drying, the sulfonated anionic starch polymer DGSS is obtained. This inhibitor is applied to the flotation separation of copper-molybdenum mixed concentrates. Combined with a closed-circuit process of one roughing, one scavenging, and four cleaning stages, and employing a gradient reduction of reagents from roughing to cleaning and staged addition of kerosene, it can selectively inhibit copper sulfide minerals such as chalcopyrite at extremely low dosages, while having minimal impact on the floatability of molybdenite. This inhibitor does not use any toxic substances such as cyanide, Knox reagent, or sodium sulfide, and has advantages such as good selectivity, low reagent consumption, environmental friendliness, simple preparation process, and ease of industrial production.

[0040] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing an environmentally friendly copper-molybdenum separation inhibitor, characterized in that: Starch and formamide were mixed, stirred at room temperature, and then cooled to -5°C in an ice-water bath. Chlorosulfonic acid was added dropwise to the resulting mixture at a temperature maintained at -5 °C to carry out a sulfonation reaction; After the reaction is complete, add sodium hydroxide solution to neutralize to pH 7-8; Anhydrous methanol was added to the neutralized system to precipitate the product, and the precipitate was collected by centrifugation. The precipitate was washed with anhydrous methanol and dried at 40-60 °C for 24 h to obtain the environmentally friendly copper-molybdenum separation inhibitor.

2. The preparation method according to claim 1, characterized in that: The ratio of starch to formamide is 2-5 g: 20-50 mL, the amount of chlorosulfonic acid added is 5-12.5 mL, and the adding time is 60-90 min.

3. The preparation method according to claim 1, characterized in that: The stirring time at room temperature is 30-60 minutes, and the washing is performed 3-5 times.

4. The preparation method according to claim 1, characterized in that: The stirring speed during the sulfonation reaction and neutralization process is 600~1000 r / min.

5. The preparation method according to claim 1, characterized in that: The volume ratio of anhydrous methanol to formamide is 3~5:

1.

6. The preparation method according to claim 1, characterized in that: The starch is corn starch, wheat starch, rice starch, potato starch, or cassava starch.

7. An environmentally friendly copper-molybdenum separation inhibitor, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 6.

8. The application of the environmentally friendly copper-molybdenum separation inhibitor as described in claim 7 in the flotation separation of copper-molybdenum mixed concentrate, characterized in that... Includes the following steps: S1: Grind the copper-molybdenum mixed concentrate to a thickness of -0.038 mm, with 80%~90% of the concentrate being 0.038 mm, and adjust the slurry concentration to 35%~40%. S2: Add sodium hydroxide to the slurry obtained in S1 to adjust the pH to 11.5~12.5, and then add the inhibitor, kerosene and methyl isobutyl methanol in sequence for a roughing process to obtain roughing concentrate and roughing tailings; wherein the amount of inhibitor is 1500~2500 g / t, the amount of kerosene is 100~300 g / t, and the amount of methyl isobutyl methanol is 30~100 g / t; S3: The inhibitor, kerosene, and methyl isobutyl methanol are added sequentially to the roughing tailings obtained in S2 for a single scavenging process to obtain scavenged concentrate and copper concentrate. The scavenged concentrate is then returned to the roughing operation in S2. The amount of inhibitor used is 150-250 g / t, the amount of kerosene used is 50-100 g / t, and the amount of methyl isobutyl methanol used is 15-50 g / t. S4: Perform four cleaning operations on the rough concentrate obtained from S2, specifically including: S4.1: In the first fine selection, 300~500 g / t of the inhibitor is added to obtain fine concentrate and fine tailings. The fine tailings are returned to the roughing operation in S2. S4.2: Add 150-250 g / t of the inhibitor and 50-100 g / t of kerosene to the refined concentrate obtained in S4.1 for a second refinement to obtain refined concentrate and refined tailings. Return the refined tailings to S4.

1. S4.3: Add 50-70 g / t of the inhibitor to the refined concentrate obtained in S4.2 for a third refining process to obtain refined concentrate and refined tailings. Return the refined tailings to S4.

2. S4.4: Add 20-40 g / t of the inhibitor and 20-40 g / t of kerosene to the refined concentrate obtained in S4.3 for a fourth refinement to obtain molybdenum concentrate and refined tailings. Return the refined tailings to S4.3 to form a closed loop.

9. The application as described in claim 8, characterized in that: The dosage of the inhibitor mentioned in S2 is 2000~2500 g / t, the dosage of kerosene is 200~300 g / t, and the dosage of methyl isobutyl methanol is 80~100 g / t.

10. The application as described in claim 8, characterized in that: The dosage of the inhibitor mentioned in S3 is 200~250 g / t, the dosage of kerosene is 80~100 g / t, and the dosage of methyl isobutyl methanol is 30~50 g / t.

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