A flotation agent for copper, molybdenum, gold and silver sulfide ore and a cascade enrichment flotation method for copper, molybdenum, gold and silver sulfide ore

Abstract

The present invention discloses a flotation agent for copper, molybdenum, gold, and silver sulfide ores and a cascade enrichment flotation method for copper, molybdenum, gold, and silver sulfide ores, relating to the field of mineral flotation technology. The composite depressant is compounded with nitrated modified humic acid and nano-silicon dioxide in a certain mass ratio. This depressant enhances the simultaneous capture of copper, molybdenum, gold, and silver under the action of a composite collector. The composite collector is compounded with mercaptobenzothiazole and hydroxamic acid, synergistically improving the recovery rate of gold and silver. The process includes a mixed flotation stage and a cascade separation stage, ultimately yielding a copper, molybdenum, gold, and silver concentrate. This process addresses the difficulties in separating sulfur and precious metals and the high toxicity of the reagents in traditional processes, offering the advantages of high efficiency, environmental protection, and a short process.

Description

Technical Field

[0001] The present invention relates to the technical field of mineral flotation, and in particular to a flotation agent for copper, molybdenum, gold, and silver sulfide ores and a cascade enrichment flotation method for the copper, molybdenum, gold, and silver sulfide ores. Background Art

[0002] In the beneficiation of copper, molybdenum, gold, silver, and sulfur polymetallic ores, the efficient suppression and selective separation of pyrite (FeS2), a primary associated mineral, has always been a technical challenge. Traditional processes commonly use cyanide as a suppressant. While this suppressant effectively suppresses pyrite, it carries the risk of severe environmental pollution and the complexation of cyanide with gold and silver significantly reduces precious metal recovery. Furthermore, while conventional suppressants such as lime can replace cyanide to suppress sulfur, their non-selective nature often results in the simultaneous suppression of molybdenum minerals, resulting in reduced molybdenum recovery. Furthermore, lignin sulfonate suppressants, due to their adsorption and shielding effects on gold and silver, prevent gold and silver recoveries from exceeding 70%.

[0003] Existing technologies also suffer from collector performance deficiencies. Traditional sulfide-based collectors have weak adsorption capacity for gold and silver. Furthermore, the similar floatability of pyrite and valuable minerals in polymetallic systems forces the separation of copper, molybdenum, gold, and silver to rely on a multi-stage separation process, which not only increases reagent and energy consumption but also reduces overall separation efficiency. Therefore, developing a novel separation method that combines environmental friendliness, high selectivity, and multimetallic synergistic recovery efficiency has become a key direction for addressing technical bottlenecks in this field.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a flotation agent for copper, molybdenum, gold and silver sulfide ores, wherein the composite depressant is combined with pyrite Fe by carboxyl group (-COOH) 3+ Chelation to form a hydrophilic film; -NO2 functional group and Cu on the surface of chalcopyrite (CuFeS2) 2+ Generates [Cu(NO2)4] 3- The complex inhibits copper-activated sulfur. Surface silanol (Si-OH) groups on nanosilica (n-SiO2) form hydrogen bonds (bond length ≤ 2.1 Å) with the interlayer sulfur of molybdenite (MoS2), protecting the floatability of molybdenum. The composite collector selectively adsorbs chalcopyrite via the S-Cu bond. The C=N-OH group coordinates with vacant surface orbitals of gold and silver, improving gold and silver recovery.

[0006] The second object of the present invention is to provide a cascade enrichment flotation method for copper, molybdenum, gold and silver sulfide ores, which uses the above-mentioned flotation reagent for flotation separation.

[0007] The present invention is achieved in that:

[0008] The present invention provides a flotation reagent for copper, molybdenum, gold and silver sulfide ores, the reagent comprising a composite depressant and a composite collector;

[0009] The composite inhibitor comprises nitrified modified humic acid and nano silicon dioxide;

[0010] The composite collector comprises hydroxamic acid and mercaptobenzothiazole.

[0011] In some preferred embodiments, the composite inhibitor is formed by compounding the nitrated modified humic acid and the nano-silicon dioxide through mechanochemical activation;

[0012] The nitrated modified humic acid (N-HA) has a nitro content of ≥5.2 wt% and a carboxyl content of ≥4.5 mmol / g;

[0013] The nano-silicon dioxide (n-SiO2) has a mesoporous structure, a specific surface area of ​​≥600m² / g, and a surface silanol density of ≥3.8 OH / nm²;

[0014] The mass ratio of the nitrated modified humic acid to the nano-silicon dioxide is 1:1-2.

[0015] In some preferred embodiments, the preparation method of the nitrated modified humic acid comprises the following steps: mixing humic acid and water in a mass ratio of 1:7-10, ultrasonically treating for 30-60 minutes, and then mixing humic acid and concentrated nitric acid in a mass ratio of 1:6-8 in an ice water bath at 0-5°C, controlling the system temperature to less than 10°C, to carry out a nitration reaction; then heating to 58-62°C, adding urea, and reacting for 4-8 hours until the degree of nitration is ≥15% to obtain a reaction solution;

[0016] The reaction solution was adjusted to pH 7-8 with alkaline solution, then centrifuged at 8000-10000 rpm for 15-30 min, and dialyzed for 45-50 h after the centrifugation. Finally, the solution was freeze-dried to obtain a yellow powder with a yield of ≥85%.

[0017] In some preferred embodiments, the mass ratio of the hydroxamic acid to the mercaptobenzothiazole is 1:2-3;

[0018] The hydroxamic acid is a C7-C9 alkyl hydroxamic acid, and the hydroxamic group content is ≥90%;

[0019] The purity of the mercaptobenzothiazole is ≥98%, and the sulfur content is ≥25wt%.

[0020] In some preferred embodiments, the contact angle of the composite inhibitor to pyrite decreases by ≥40°, and the contact angle change to molybdenite changes by ≤5°.

[0021] In some preferred embodiments, the adsorption energy of the composite collector for Au is ≤-2.9 eV, and the adsorption energy for CuFeS2 is ≤-3.2 eV; in the pH range of 8-10, the fluctuation of the gold and silver adsorption rate is ≤5%.

[0022] The present invention also provides a cascade enrichment flotation method using a flotation reagent for copper, molybdenum, gold and silver sulfide ores, the steps of which include:

[0023] Grinding the raw copper, molybdenum, gold, silver and sulfide ore and adding water to prepare slurry;

[0024] The pH value of the slurry is adjusted to 8.5-10, and 80-120 g / t of the composite collector is added thereto to obtain a copper, molybdenum, gold and silver mixed flotation concentrate and tailings;

[0025] The copper, molybdenum, gold and silver mixed flotation concentrate is subjected to three-stage roughing suppression-activation separation to obtain roughing concentrate and roughing tailings. A composite collector of 20-30g / t is added to the roughing concentrate and two rounds of concentration are performed to obtain concentrated concentrate and concentrated tailings.

[0026] The selected concentrate is copper, molybdenum, gold and silver concentrate, and the selected tailings and rougher tailings are mixed to obtain sulfur-containing tailings.

[0027] In some preferred embodiments, the three-stage roughing inhibition-activation separation process is to add different masses of composite inhibitors in roughing I, roughing II, and roughing III, and the mass ratio of the composite inhibitors added in the three stages is: 4-6:2-4:1-3; before performing the roughing II, a molybdenum activator is added, the stirring time is ≥2 minutes, and the mixing is uniform; during the two selection processes, the pH value of the system is controlled to be 8.0-8.5.

[0028] In some preferred embodiments, the copper-molybdenum-gold-silver mixed flotation concentrate has a Cu content ≥15%, a Mo content ≥0.5%, an Au content ≥1 g / t, and an Ag content ≥30 g / t.

[0029] In some preferred embodiments, the copper-molybdenum-gold-silver concentrate has a Cu content ≥25%, a Mo content ≥1.2%, an Au content ≥10 g / t, and an Ag content ≥150 g / t, and a sulfur content ≤5%; the copper-molybdenum-gold-silver concentrate has a Cu recovery rate ≥90%, a Mo recovery rate ≥85%, an Au recovery rate ≥80%, and an Ag recovery rate ≥75%; and a sulfur suppression rate ≥93%.

[0030] The present invention has the following beneficial effects:

[0031] (1) The flotation agent for copper, molybdenum, gold and silver sulfide ores provided by the present invention comprises a nitrated modified humic acid in the composite inhibitor which reacts with the Fe of pyrite via a carboxyl group. 3+ Chelation forms a hydrophilic film, while its -NO2 functional group interacts with Cu on the surface of chalcopyrite. 2+The formation of a stable complex selectively inhibits pyrite and reduces copper activation of sulfur. Nanosilica forms hydrogen bonds with the interlayer sulfur of molybdenite through silanol groups, protecting the floatability of molybdenum. The composite collector, composed of thiobenzothiazole, efficiently captures chalcopyrite through a strong S-Cu bond, while the C=N-OH group of hydroxylamine coordinates with the vacant surface orbitals of gold and silver, increasing recovery by 30% to 40%, addressing the weak adsorption of gold and silver by traditional collectors.

[0032] (2) The cascade enrichment process proposed in the present invention not only achieves efficient separation and enrichment of multiple metals by optimizing the reagent system and operating parameters in the flotation and separation stages, but also reduces energy consumption by simplifying the process, thus achieving both environmental friendliness and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 This is a process flow chart of the enrichment and flotation method of copper, molybdenum, gold and silver sulfide ores in this application. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0036] A first aspect of the present invention provides a flotation reagent for copper, molybdenum, gold and silver sulfide ores, the reagent comprising a composite depressant and a composite collector;

[0037] The composite inhibitor includes nitrated modified humic acid and nano-silica, and the composite inhibitor is formed by compounding the nitrated modified humic acid and the nano-silica through mechanochemical activation; the nitro content of the nitrated modified humic acid (N-HA) is ≥5.2wt%, and the carboxyl content is ≥4.5mmol / g; the nano-silica (n-SiO2) has a mesoporous structure, a specific surface area ≥600m² / g, and a surface silanol density ≥3.8 OH / nm².

[0038] Nitrified modified humic acid reacts with pyrite Fe through carboxyl group (-COOH) 3+ Chelation, forming a hydrophilic film, -NO2 functional group, and Cu on the surface of chalcopyrite (CuFeS2)2+ Generates [Cu(NO2)4] 3- The complex inhibits the activation of sulfur by copper; the surface silanol (Si-OH) of nano-silica (n-SiO2) forms hydrogen bonds (bond length ≤ 2.1Å) with the sulfur between the layers of molybdenite (MoS2), protecting the floatability of molybdenum.

[0039] In some specific embodiments of the present invention, the mass ratio of the nitrated modified humic acid to the nano-silicon dioxide is 1:1-2, for example, any value of 1:1 or 1:2 or a range of two values, preferably 1:1.5. When the proportion of nano-silicon dioxide (n-SiO2) is greater than 66%, the gold and silver recovery rate decreases by ≥25%. At this time, the silanol group will excessively adsorb Au. 0 ; When the proportion of nitrified modified humic acid (N-HA) is greater than 50%, the molybdenum grade decreases by ≥18%.

[0040] In some specific embodiments of the present invention, the preparation method of the nitrated modified humic acid comprises the following steps: mixing humic acid and water in a mass ratio of 1:7-10, ultrasonically treating for 30-60 minutes, removing ash, controlling the ash content to be ≤3%, mixing humic acid and concentrated nitric acid in a mass ratio of 1:6-8 in an ice water bath at 0-5°C, controlling the system temperature to be <10°C, and carrying out a nitration reaction; then heating to 58-62°C, adding urea, which inhibits excessive oxidation, and reacting for 4-8 hours until the nitration degree is ≥15% to obtain a reaction solution; wherein the nitration degree is detected by FTIR detection at 1720cm -1 (-COOH) and 1530 cm -1 The (-NO2) peak intensity changes, and the nitrification degree is measured by the N element content.

[0041] The reaction solution was adjusted to pH 7-8 with alkaline solution, then centrifuged at 8000-10000 rpm for 15-30 minutes. After centrifugation, the solution was dialyzed for 45-50 hours to remove free nitrate. Finally, the solution was freeze-dried to obtain a yellow powder with a yield of ≥85%.

[0042] In some specific embodiments of the present invention, the composite collector comprises hydroxamic acid and mercaptobenzothiazole, wherein the hydroxamic acid is a C7~C9 alkyl hydroxamic acid with a hydroxamic group content of ≥90%; the purity of mercaptobenzothiazole is ≥98% and the sulfur content is ≥25wt%.

[0043] The composite collector enhances the selective adsorption of copper, molybdenum, gold and silver minerals through synergistic action. Mercaptobenzothiazole (MBT) binds to Cu on the surface of chalcopyrite through its thiol (-SH) 2+Strong chemical adsorption is formed (adsorption energy ≤ -3.2 eV), and the high stability of the S-Cu bond ensures the efficient and selective capture of chalcopyrite while reducing the accidental capture of pyrite; hydroxamic acid chelates and coordinates with the empty d orbitals on the gold and silver surfaces through the C=N-OH functional group (Au adsorption energy ≤ -2.9 eV). Its unique electron donor properties can effectively overcome the inertness of the gold and silver surfaces and significantly enhance the adsorption capacity of fine-particle gold and silver.

[0044] In some embodiments of the present invention, the mass ratio of hydroxamic acid to mercaptobenzothiazole is 1:2-3, for example, any value or a range consisting of two values ​​of 1:2 or 1:3, preferably 1:2.5. Within this range, mercaptobenzothiazole preferentially adsorbs copper minerals to form a hydrophobic layer, while hydroxamic acid is directed onto the gold and silver surfaces, further inhibiting pyrite flotation through steric hindrance, thereby increasing gold and silver recovery by 30% to 40%. Furthermore, this composite system maintains high activity under weakly alkaline conditions (pH 8.5-9.0), avoiding the inhibition of molybdenum in a strongly alkaline environment while reducing reagent consumption, achieving both high efficiency and economical efficiency.

[0045] In some specific embodiments of the present invention, the composite depressant reduces the contact angle of pyrite by ≥40° and changes the contact angle of molybdenite by ≤5°, and is suitable for flotation separation of precious metal-containing sulfide ores.

[0046] In some specific embodiments of the present invention, the adsorption energy of the composite collector for Au is ≤-2.9eV, and the adsorption energy for CuFeS2 is ≤-3.2eV; in the pH range of 8-10, the fluctuation of the gold and silver adsorption rate is ≤5%; and it is suitable for flotation separation of copper, molybdenum, gold and silver ores.

[0047] A second aspect of the present invention provides a cascade enrichment flotation method for copper, molybdenum, gold, and silver sulfide ores, which uses the above-mentioned flotation reagent and comprises the following steps:

[0048] Grinding the raw copper, molybdenum, gold, silver and sulfide ore and adding water to prepare slurry;

[0049] The pH value of the slurry is adjusted to 8.5-10, and 80-120 g / t of the composite collector is added thereto to obtain a copper, molybdenum, gold and silver mixed flotation concentrate and tailings;

[0050] The copper, molybdenum, gold and silver mixed flotation concentrate is subjected to three-stage roughing suppression-activation separation to obtain roughing concentrate and roughing tailings. A composite collector of 20-30g / t is added to the roughing concentrate and two rounds of concentration are performed to obtain concentrated concentrate and concentrated tailings.

[0051] The selected concentrate is copper, molybdenum, gold and silver concentrate, and the selected tailings and rougher tailings are mixed to obtain sulfur-containing tailings.

[0052] In some specific embodiments of the present invention, the three-stage roughing inhibition-activation separation process is to add composite inhibitors of different masses into roughing I, roughing II and roughing III, and the mass ratio of the composite inhibitors added into the three stages is: 4-6:2-4:1-3, for example, any point value among 4:2:1, 4:2:2, 4:3:1, 4:3:2, 4:4:1, 4:4:2, 4:4:3, 5:2:1, 5:2:2, 5:3:1, 5:3:2, 5:4:1, 5:4:2, 5:4:3, 6:2:1, 6:2:2, 6:3:1, 6:3:2, 6:4:1, 6:4:2 and 6:4:3, or a range value consisting of any two point values;

[0053] Before the roughing II, a molybdenum activator is added, the stirring time is ≥2 minutes, and the mixture is evenly mixed; during the two selection processes, the pH value of the system is controlled to be 8.0-8.5.

[0054] In some specific embodiments of the present invention, the copper-molybdenum-gold-silver mixed flotation concentrate has a Cu content ≥15%, a Mo content ≥0.5%, an Au content ≥1 g / t, and an Ag content ≥30 g / t.

[0055] In some specific embodiments of the present invention, the copper-molybdenum-gold-silver concentrate has a Cu content ≥25%, a Mo content ≥1.2%, an Au content ≥10 g / t, and an Ag content ≥150 g / t, and a sulfur content ≤5%; the copper-molybdenum-gold-silver concentrate has a Cu recovery rate ≥90%, a Mo recovery rate ≥85%, an Au recovery rate ≥80%, and an Ag recovery rate ≥75%; and a sulfur suppression rate ≥93%.

[0056] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0057] Example 1

[0058] This embodiment provides a cascade enrichment flotation method for copper, molybdenum, gold and silver sulfide ores, the process is as follows: Figure 1 As shown, the mineral raw material in this example is a copper-molybdenum-gold-silver-sulfur polymetallic ore from a location in Inner Mongolia. The main metal mineral components are: chalcopyrite, molybdenite, native gold, native silver, and pyrite. The gangue minerals are mainly quartz and feldspar. The raw ore grade is: Cu 1.8g / t, Mo 0.6g / t, Au 1.5g / t, Ag 40g / t, S 20g / t. The main steps include:

[0059] (1) Pharmaceutical preparation:

[0060] Preparation of composite inhibitor: Humic acid and deionized water were mixed in a mass ratio of 1:10 and ultrasonically treated at 40kHz, 600W for 30 minutes to fully disperse and remove ash (control ash content ≤ 3%). Subsequently, 100g of pretreated humic acid was slowly added to 500mL of concentrated nitric acid in an ice-water bath at 0-5°C, strictly controlling the temperature below 10°C to inhibit side reactions. After the nitration reaction was heated to 60±2°C, 10g of urea was added as an antioxidant and the reaction was allowed to proceed for 4 hours. During this time, the FTIR spectra at 1720cm -1 (-COOH) and 1530 cm -1 (-NO2) characteristic peak intensity ensures that the nitrification degree is ≥15% (calculated as N element content).

[0061] After the reaction, the pH was adjusted to 7-8 with NaOH, and insoluble impurities were removed by centrifugation at 8000 rpm for 15 minutes. The product was then dialyzed for 48 hours to a conductivity of <50 μS / cm. Finally, the product was freeze-dried to obtain a yellow powdered N-HA product with a yield of ≥85%, a nitro content of 5.8 wt%, and a carboxyl content of 4.7 mmol / g.

[0062] At the same time, highly active nano-silica (n-SiO2) with a specific surface area of ​​620m² / g and a silanol density of 4.0 OH / nm² was selected as the composite component.

[0063] N-HA and n-SiO2 were mixed by mechanical ball milling at an optimized mass ratio of 1:1.5, a ball-to-material ratio of 5:1, a rotation speed of 300 rpm, and a time of 30 min to prepare a composite inhibitor.

[0064] Preparation of composite collector: Mercaptobenzothiazole with a purity of 98.5% and C8 alkyl hydroxamic acid with a content of 92% are compounded in a mass ratio of 2.5:1 to prepare the composite collector.

[0065] (2) Copper, molybdenum, gold, silver and sulfur mixed flotation: The original ore is ground to -0.074mm, accounting for 80%, and the pH value of the slurry is adjusted to 9.0 with Na2CO3. A composite collector of 80g / t is added to obtain copper, molybdenum, gold and silver mixed flotation concentrate and tailings.

[0066] (3) Copper, molybdenum, gold, silver and sulfur separation operation: The copper, molybdenum, gold and silver mixed flotation concentrate is subjected to a three-stage roughing inhibition-activation separation process. 150 g / t, 90 g / t and 60 g / t of composite inhibitors are added to roughing I, roughing II and roughing III respectively. Then, a molybdenum activator (NH4)2MoO440 g / t is added before roughing II. The stirring time is 3 min. After the three-stage roughing inhibition-activation separation process, roughing concentrate and roughing tailings are obtained.

[0067] Adding 20 g / t of a composite collector to the rougher concentrate, performing two concentrations, controlling the pH value to 8.3 during the concentration process, and preparing a concentrated concentrate and a concentrated tailings;

[0068] The selected concentrate is copper, molybdenum, gold and silver concentrate, and the selected tailings and rougher tailings are mixed to obtain sulfur-containing tailings.

[0069] Example 2

[0070] This embodiment provides a cascade enrichment flotation method for copper, molybdenum, gold and silver sulfide ores, the process is as follows: Figure 1 As shown, the mineral raw material in this example is a copper-molybdenum-gold-silver-sulfur polymetallic ore from a location in Inner Mongolia. The main metal mineral components are: chalcopyrite, molybdenite, native gold, native silver, and pyrite. The gangue minerals are mainly quartz and feldspar. The raw ore grade is: Cu 1.6g / t, Mo 0.5g / t, Au 1.3g / t, Ag 37g / t, S 25g / t. The main steps include:

[0071] (1) Pharmaceutical preparation:

[0072] Preparation of composite inhibitor: Humic acid and deionized water were mixed in a mass ratio of 1:10 and ultrasonically treated at 40kHz, 600W for 30 minutes to fully disperse and remove ash (control ash content ≤3%). Subsequently, 100g of pretreated humic acid was slowly added to 500mL of concentrated nitric acid in an ice-water bath at 0-5°C, strictly controlling the temperature below 10°C to inhibit side reactions. After the nitration reaction was heated to 60±2°C, 10g of urea was added as an antioxidant and the reaction was allowed to proceed for 4 hours. During this period, the 1720cm -1 (carboxyl) and 1530cm -1 (Nitro) characteristic peak intensity ensures that the nitration degree is ≥15% (calculated as N element content).

[0073] After the reaction, the pH was adjusted to 7-8 with NaOH, and insoluble impurities were removed by centrifugation at 8000 rpm for 15 minutes. The product was then dialyzed for 48 hours to a conductivity of <50 μS / cm. Finally, the product was freeze-dried to obtain a yellow powdered N-HA product with a yield of ≥85%, a nitro content of 5.8 wt%, and a carboxyl content of 4.7 mmol / g.

[0074] At the same time, highly active nano-silica (n-SiO2) with a specific surface area of ​​620m² / g and a silanol density of 4.0 OH / nm² was selected as the composite component.

[0075] N-HA and n-SiO2 were mixed by mechanical ball milling at an optimized mass ratio of 1:2, a ball-to-material ratio of 5:1, a rotation speed of 300 rpm, and a time of 30 min to prepare a composite inhibitor.

[0076] Preparation of composite collector: Mercaptobenzothiazole with a purity of 98.5% and C8 alkyl hydroxamic acid with a content of 92% are compounded in a mass ratio of 2.5:1 to prepare the composite collector.

[0077] (2) Copper, molybdenum, gold, silver and sulfur mixed flotation: The original ore is ground to -0.074mm, accounting for 80%, and the pH value of the slurry is adjusted to 9.0 with Na2CO3. A composite collector of 80g / t is added to obtain copper, molybdenum, gold and silver mixed flotation concentrate and tailings.

[0078] (3) Copper, molybdenum, gold, silver and sulfur separation operation: The copper, molybdenum, gold and silver mixed flotation concentrate is subjected to a three-stage roughing inhibition-activation separation process. 150 g / t, 90 g / t and 60 g / t of composite inhibitors are added to roughing I, roughing II and roughing III respectively. Then, a molybdenum activator (NH4)2MoO440 g / t is added before roughing II. The stirring time is 3 min. After the three-stage roughing inhibition-activation separation process, roughing concentrate and roughing tailings are obtained.

[0079] Adding 20 g / t of a composite collector to the rougher concentrate, performing two concentrations, controlling the pH value to 8.3 during the concentration process, and preparing a concentrated concentrate and a concentrated tailings;

[0080] The selected concentrate is copper, molybdenum, gold and silver concentrate, and the selected tailings and rougher tailings are mixed to obtain sulfur-containing tailings.

[0081] Comparative Example 1

[0082] This comparative example provides a flotation separation method for copper, molybdenum, gold and silver sulfide ores. The other conditions of this comparative example are the same as those of Example 1, except that the ratio of N-HA to n-SiO2 in the composite depressant is 2:1.5;

[0083] The ratio of mercaptobenzothiazole to C8 alkyl hydroxamic acid in the composite collector is 2.5:1.5.

[0084] The comparative results of the copper, molybdenum, gold and silver recovery rates obtained in Examples 1-2 and Comparative Example 1 are shown in Table 1.

[0085] Table 1. Comparison of copper, molybdenum, gold and silver recovery rates

[0086]

[0087] The experimental results demonstrate the superiority of the cascade enrichment flotation method by comparing the copper and molybdenum grades and recoveries of Examples 1 and 2, as well as the comparative example. Example 1 demonstrated the most outstanding copper enrichment, with a final concentrate copper grade of 26.7 g / t and a recovery of 89%, significantly higher than the comparative example's 24.32 g / t and 87.69% respectively. Molybdenum recovery also exhibited a similar trend, with Example 1 achieving a final concentrate molybdenum grade of 1.5 g / t and a recovery of 84%, both superior to the comparative example's 1.25 g / t and 80.36% respectively. This demonstrates that optimizing the ratio of the composite depressant (N-HA and n-SiO2) and the composite collector (sulfanylbenzothiazole and CS-alkylhydroxylamine) can effectively improve the separation efficiency of the target mineral.

[0088] Further analysis revealed that the primary difference between Example 1 (N-HA:n-SiO2 = 1:1.5) and Example 2 (N-HA:n-SiO2 = 1:2) lies in the reagent ratio. While Example 1 offers a higher copper recovery rate, Example 2 achieves a slightly better molybdenum flotation recovery rate (87.55% vs. 87%). This may be due to the reduced inhibition of molybdenum by the increased N-HA ratio in the latter. Furthermore, the increased proportion of CS alkylhydroxylamine in the collector may also enhance molybdenum capture. This phenomenon suggests that the reagent ratio needs to be tailored to the characteristics of the target mineral. If copper is the primary target, the ratio of Example 1 can be used; if molybdenum recovery is also important, the optimization approach outlined in Example 2 can be considered.

[0089] The comparative example, lacking an optimized reagent ratio, yielded significantly lower grade and recovery than the two examples. This highlights the importance of staged addition of inhibitors and activators in the cascade enrichment flotation method. By combining cascaded inhibition (150 g / t → 90 g / t → 60 g / t) and selective activation in the roughing stage, this method achieves highly efficient mineral separation. For future industrial applications, it is recommended to adjust the reagent ratio in real time based on fluctuations in ore composition and utilize monitoring methods such as FTIR to ensure reaction stability, thereby maximizing economic benefits.

[0090] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A flotation reagent for copper, molybdenum, gold and silver sulfide ores, characterized in that: The reagents include a composite inhibitor and a composite collector; The composite inhibitor comprises nitrified modified humic acid and nano silicon dioxide; The composite collector comprises hydroxamic acid and mercaptobenzothiazole; The preparation method of the nitrated modified humic acid comprises the following steps: mixing humic acid and water in a mass ratio of 1:7-10, ultrasonically treating for 30-60 minutes, then mixing humic acid and concentrated nitric acid in a mass ratio of 1:6-8 in an ice water bath at 0-5°C, controlling the system temperature to less than 10°C, and performing a nitration reaction; then heating to 58-62°C, adding urea, and reacting for 4-8 hours until the nitration degree is ≥15% to obtain a reaction solution; The reaction solution was adjusted to pH 7-8 with alkaline solution, then centrifuged at 8000-10000 rpm for 15-30 min. After centrifugation, the solution was dialyzed for 45-50 h. Finally, the solution was freeze-dried to obtain a yellow powder with a yield of ≥85%.

2. A flotation reagent for copper, molybdenum, gold and silver sulfide ores according to claim 1, characterized in that: The composite inhibitor is formed by compounding the nitrated modified humic acid and the nano-silicon dioxide through mechanochemical activation; The nitrated modified humic acid (N-HA) has a nitro content of ≥5.2 wt% and a carboxyl content of ≥4.5 mmol / g; The nano-silicon dioxide (n-SiO2) has a mesoporous structure and a specific surface area of ​​600m 2 / g, surface silanol density ≥3.8OH / nm 2 ; The mass ratio of the nitrated modified humic acid to the nano-silicon dioxide is 1:1-2.

3. A flotation reagent for copper, molybdenum, gold and silver sulfide ores according to claim 1, characterized in that: The mass ratio of the hydroxamic acid to the mercaptobenzothiazole is 1:2-3; The hydroxamic acid is a C7-C9 alkyl hydroxamic acid, and the hydroxamic group content is ≥90%; The purity of the mercaptobenzothiazole is ≥98%, and the sulfur content is ≥25wt%.

4. A flotation reagent for copper, molybdenum, gold and silver sulfide ores according to claim 1, characterized in that: The contact angle of the composite inhibitor to pyrite is reduced by ≥40°, and the contact angle change to molybdenite is ≤5°.

5. The flotation reagent for copper, molybdenum, gold and silver sulfide ores according to claim 1, characterized in that: The adsorption energy of the composite collector for Au is ≤-2.9eV, and the adsorption energy for CuFeS2 is ≤-3.2eV; within the pH range of 8-10, the fluctuation of the gold and silver adsorption rate is ≤5%.

6. A cascade enrichment flotation method for copper, molybdenum, gold and silver sulfide ores, characterized by: The flotation reagent for copper, molybdenum, gold and silver sulfide ores according to any one of claims 1 to 5 is used, and the steps include: Grinding the raw copper, molybdenum, gold, silver and sulfide ore and adding water to prepare slurry; The pH value of the slurry is adjusted to 8.5-10, and 80-120 g / t of the composite collector is added thereto to obtain a copper, molybdenum, gold and silver mixed flotation concentrate and tailings; The copper, molybdenum, gold and silver mixed flotation concentrate is subjected to three-stage roughing suppression-activation separation to obtain roughing concentrate and roughing tailings. A composite collector of 20-30g / t is added to the roughing concentrate and two rounds of concentration are performed to obtain concentrated concentrate and concentrated tailings. The selected concentrate is copper, molybdenum, gold and silver concentrate, and the selected tailings and rougher tailings are mixed to obtain sulfur-containing tailings.

7. The cascade enrichment flotation method for copper, molybdenum, gold and silver sulfide ores according to claim 6, characterized in that: The three-stage roughing inhibition-activation separation process is to add composite inhibitors of different masses in roughing I, roughing II, and roughing III, and the mass ratio of the composite inhibitors added in the three stages is: 4-6:2-4:1-3; before performing roughing II, a molybdenum activator is added, and the stirring time is ≥2 minutes to mix evenly; during the two cleaning processes, the pH value of the system is controlled to be 8.0-8.

5.

8. The cascade enrichment flotation method for copper, molybdenum, gold and silver sulfide ores according to claim 6, characterized in that: The copper-molybdenum-gold-silver mixed flotation concentrate has a Cu content of ≥15%, a Mo content of ≥0.5%, an Au content of ≥1 g / t, and an Ag content of ≥30 g / t.

9. The cascade enrichment flotation method for copper, molybdenum, gold and silver sulfide ores according to claim 6, characterized in that: The copper-molybdenum-gold-silver concentrate has a Cu content of ≥25%, a Mo content of ≥1.2%, an Au content of ≥10 g / t, and an Ag content of ≥150 g / t, and a sulfur content of ≤5%; the copper-molybdenum-gold-silver concentrate has a Cu recovery rate of ≥90%, a Mo recovery rate of ≥85%, an Au recovery rate of ≥80%, and an Ag recovery rate of ≥75%; and a sulfur inhibition rate of ≥93%.

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