A collector for use in the flotation of sphalerite without copper sulphate activation and a method for its preparation

Abstract

This invention discloses a collector for copper sulfate-free flotation of sphalerite and its preparation method. The active component of the collector includes a straight-chain alkylamine or an alkoxy / phenoxy-substituted amine, wherein the alkyl group in the straight-chain alkylamine is a C12-C18 straight-chain alkyl group, and the substituent in the alkoxy / phenoxy-substituted amine is a C2-C4 alkyl or phenyl group, and the linking group is a C2-C3 alkylene group. The collector can be prepared by the reduction reaction of straight-chain fatty acids with ammonia under the action of a catalyst, or by the amination reaction of alkoxy alcohols / phenoxy alcohols with ammonia under pressure. When used for flotation of sphalerite-containing slurry, this collector can enhance adsorption and improve the hydrophobicity and floatability of sphalerite by means of the coordination of the amino nitrogen atom with zinc ions on the surface of sphalerite without the need for the addition of copper sulfate activator. This collector has low dosage, good selectivity, and can reduce copper ion contamination and reagent costs, making it suitable for green and efficient flotation of sphalerite.

Description

Technical Field

[0001] This invention relates to the field of mineral processing reagents, and in particular to a collector for copper sulfate-free activation flotation of sphalerite and its preparation method. Background Technology

[0002] Zinc is an important base metal, widely used in alloy smelting, corrosion-resistant materials, battery manufacturing, and high-end equipment. Sphalerite is one of the most important zinc-bearing minerals, usually occurring in association with galena, pyrite, and gangue minerals such as calcite and dolomite. Its complex ore composition and fine grain size pose significant challenges to beneficiation and separation. Flotation is the primary method for enriching and recovering sphalerite, and the interaction strength and selectivity between the collector and the mineral surface directly affect flotation parameters. Existing sphalerite flotation processes often employ copper sulfate activation followed by the addition of xanthate collectors to create active sites on the sphalerite surface suitable for xanthate adsorption, thus achieving sphalerite flotation. However, this process is highly dependent on copper sulfate activators, increasing reagent consumption and production costs, and leaving copper ions in the slurry and beneficiation wastewater, increasing the difficulty of subsequent wastewater treatment and potentially posing a risk of heavy metal pollution. Therefore, developing collectors that can act directly on the sphalerite surface without copper sulfate activation is an important direction for improving the green and efficient recovery of sphalerite.

[0003] Currently, some copper sulfate-free activated sphalerite collectors have been proposed, such as isohydroxamic acid, heterocyclic chelate, and xanthate collectors. While these collectors can interact with the sphalerite surface under certain conditions, they still suffer from insufficient selectivity, unsatisfactory separation of pyrite or gangue minerals, strong dependence on pulp pH, insufficient reagent stability, or excessively high dosages. These issues make it difficult to fully meet the requirements of industrial flotation of complex lead-zinc sulfide ores. Especially with the increasing prevalence of lean, fine, and complex ores, traditional copper sulfate-activated xanthate systems face significant environmental pressures and complex reagent formulations, while existing copper-free activated collectors struggle to balance collection capacity, selectivity, cost, and stability. Therefore, it is necessary to provide an amine collector that can be used without the addition of copper sulfate activator, so that the amine nitrogen atom in the molecule can coordinate with the zinc ions on the surface of sphalerite, thereby enhancing the adsorption stability of the collector on the surface of sphalerite, and improving the hydrophobic properties and flotation selectivity through the straight-chain alkyl, alkoxy / phenoxy structure, thereby achieving effective separation of sphalerite from gangue minerals. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a collector for sphalerite flotation without copper sulfate activation and its preparation method. The collector comprises straight-chain alkylamines or alkoxy / phenoxy-substituted amines, which can be prepared through fatty acid reductive amination or alcohol amination reactions. When used in the flotation of sphalerite-containing pulp, this collector can react with zinc ions on the surface of sphalerite without the need for the addition of copper sulfate activator, thereby improving the floatability and selectivity of sphalerite.

[0005] This invention can be achieved through the following technical solutions: A collector for copper sulfate-free activated flotation of sphalerite, wherein the active component of the collector comprises a straight-chain alkylamine of Formula 1 or an alkoxy / phenoxy-substituted amine of Formula 2: Formula 1:

[0006] Wherein, R is a straight-chain alkyl group of C12 to C18; Formula 2:

[0007] Wherein, R1 is a C2-C4 alkyl or phenyl group, and R2 is a C2-C3 alkylene group; The collector is used to float sphalerite without the addition of copper sulfate activator.

[0008] Preferably, the linear alkylamine of Formula 1 is selected from one or more of dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine.

[0009] Preferably, the alkoxy / phenoxy substituted amine of Formula 2 is selected from one or more of ethoxyethylamine, phenoxyethylamine, and butoxypropylamine.

[0010] A method for preparing a collector for copper sulfate-free activated flotation of sphalerite includes either route A or route B: Path A: C12-C18 straight-chain fatty acids are mixed with ammonia and heated to the reaction temperature under the action of a catalyst. Hydrogen is then introduced to carry out a reduction reaction, resulting in a mixed solution containing straight-chain alkylamines. After cooling the mixed solution containing straight-chain alkylamines, it is washed with deionized water until neutral, and then the straight-chain alkylamines are extracted with petroleum ether. The solution is then dried with anhydrous magnesium sulfate, purified by vacuum distillation and vacuum fractionation, to obtain the straight-chain alkylamine collector shown in Formula 1. Route B: Mix alkoxy alcohol or phenoxy alcohol with ammonia, add a catalyst, and heat to the reaction temperature under pressure to carry out an amination reaction, obtaining a mixed solution containing alkoxy / phenoxy substituted amines; after cooling the mixed solution containing alkoxy / phenoxy substituted amines to room temperature, adjust the pH to 6-7 with dilute sulfuric acid, extract with dichloromethane, dry with anhydrous sodium sulfate, purify by vacuum distillation and silica gel column chromatography to obtain the alkoxy / phenoxy substituted amine collector shown in Formula 2.

[0011] Preferably, in path A, the C12-C18 straight-chain fatty acids are selected from one or more of lauric acid, myristic acid, palmitic acid, and stearic acid.

[0012] Preferably, the catalyst in path A is Raney nickel, and the amount of catalyst used is 5% to 8% of the mass of C12 to C18 straight-chain fatty acids; the reaction temperature of the reduction reaction is 180 to 220°C, the reaction pressure is 2 to 3 MPa, and the reaction time is 8 to 12 h.

[0013] Preferably, the alkoxy alcohol or phenoxy alcohol in path B is selected from one or more of ethoxyethanol, phenoxyethanol, and butoxypropanol.

[0014] Preferably, the amination reaction in path B is carried out at a temperature of 120–150°C, a pressure of 1.5–2 MPa, and a time of 6–10 h.

[0015] Preferably, the mass fraction of the dilute sulfuric acid is 10%, the molar ratio of the alkoxy / phenoxy substituted amine to the dilute sulfuric acid is 1:1.2, and the mobile phase for the silica gel column chromatography is petroleum ether / ethyl acetate with a volume ratio of 4:1.

[0016] The above-mentioned collector is used in the copper sulfate-free flotation of sphalerite: the collector is added to the slurry containing sphalerite, and zinc flotation is carried out without the addition of copper sulfate activator to obtain sphalerite concentrate; wherein, the pH of the slurry is adjusted to 8-10 before zinc flotation, the amount of the collector is 40-60 g / t, and the slurry is adjusted for 2-3 min after the addition of the amine collector.

[0017] The beneficial effects of this invention are: This invention provides a method for preparing an amine collector for sphalerite flotation without copper sulfate activation. The collector uses straight-chain alkylamines or alkoxy / phenoxy-substituted amines as the active component, enabling direct action on sphalerite flotation without the addition of copper sulfate activator. This overcomes the problem that traditional xanthate collectors require copper ion activation for effective sphalerite collection. The amine collector molecule contains an electronically active amino nitrogen atom, which can coordinate with zinc ions on the sphalerite surface via lone pairs of electrons, forming relatively stable metal-nitrogen coordination bonds or hydrophobic complex structures. This enhances the adsorption strength and stability of the collector on the sphalerite surface, reduces the tendency of the collector to desorb from the mineral surface, and improves the hydrophobicity and floatability of sphalerite. Simultaneously, this type of collector has a weaker effect on gangue minerals such as calcite and dolomite, which is beneficial for improving the flotation separation selectivity between sphalerite and gangue minerals. In this invention, alkoxy / phenoxy-substituted amines, by further introducing alkoxy or phenoxy structures based on amino group coordination, can improve the hydrophobic properties of the molecule, reduce solubility loss in the slurry, and enhance its adsorption rate and collection effect on the sphalerite surface. Compared with traditional copper sulfate-activated xanthate systems, the collector of this invention does not require the addition of copper sulfate activator, achieving high zinc grade and zinc recovery rate at lower dosages. This reduces the consumption of copper sulfate and xanthate reagents, lowers beneficiation costs, and avoids slurry pollution, wastewater treatment pressure, and heavy metal environmental risks caused by copper ion residues. The collector of this invention has a clear preparation route, readily available raw materials, and is suitable for green, efficient, and selective flotation of sphalerite in complex sulfide lead-zinc ores, showing promising industrial application prospects. Detailed Implementation

[0018] The following provides a detailed description of the embodiments of the present invention: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0019] Example 1: This embodiment is a preferred example of the collector used in the copper sulfate-free flotation of sphalerite according to the present invention. The collector is butoxypropylamine, which belongs to the alkoxy-substituted amines of Formula 2, wherein R1 is butyl and R2 is propylene, and the structural formula is CH3(CH2)3OCH2CH2CH2NH2. The specific steps are as follows: S1. According to the mass fraction, take 14 parts of butoxypropanol, 5 parts of ammonia, 81 parts of dimethylformamide, and 0.56 parts of Raney nickel catalyst. Add butoxypropanol to dimethylformamide and stir to dissolve. Add ammonia and mix. Then add Raney nickel catalyst and stir evenly. Then transfer to a high-pressure reactor. After sealing the reactor, adjust the reaction pressure to 2 MPa and the reaction temperature to 150℃. Carry out the amination reaction for 6 h to obtain a mixed solution containing butoxypropane. S2. After cooling the mixed solution containing butoxypropylamine to room temperature, the pH was adjusted to 7 with 10% (w / w) dilute sulfuric acid, wherein the molar ratio of butoxypropylamine to dilute sulfuric acid was 1:1.2. Then, it was extracted three times with dichloromethane, the extracts were combined, and dried with anhydrous sodium sulfate for 4 h. Then, the dichloromethane was removed by vacuum distillation at 0.08 MPa and 105 °C. The remaining product of vacuum distillation was purified by silica gel column chromatography. The mobile phase of silica gel column chromatography was petroleum ether / ethyl acetate with a volume ratio of 4:1 to obtain the butoxypropylamine collector. S3. Grind the raw ore containing sphalerite into a slurry. Adjust the pH of the slurry to 10 before zinc flotation. Without adding copper sulfate activator, add the butoxypropylamine collector obtained in this example to the slurry at a dosage of 60 g / t. After adjusting the slurry for 3 minutes, perform zinc flotation to obtain sphalerite concentrate.

[0020] Example 2: This embodiment is an example of the collector used in the copper sulfate-free flotation of sphalerite according to the present invention. The collector is phenoxyethylamine, which belongs to the phenoxy-substituted amines shown in Formula 2, wherein R1 is phenyl, R2 is ethylene, and the structural formula is C6H5OCH2CH2NH2. The specific steps are as follows: S1. According to the mass fraction, take 15 parts of phenoxyethanol, 6 parts of ammonia, 79 parts of dimethylformamide, and 0.75 parts of Raney nickel catalyst; add phenoxyethanol to dimethylformamide and stir to dissolve, add ammonia and mix, then add Raney nickel catalyst and stir evenly, then transfer to a high-pressure reactor, seal the reactor, adjust the reaction pressure to 1.75 MPa, the reaction temperature to 135℃, and carry out the amination reaction for 8 h to obtain a mixed solution containing phenoxyethylamine; S2. After cooling the mixed solution containing phenoxyethylamine to room temperature, the pH was adjusted to 6.5 with 10% (w / w) dilute sulfuric acid, wherein the molar ratio of phenoxyethylamine to dilute sulfuric acid was 1:1.2. Subsequently, it was extracted three times with dichloromethane, the extracts were combined, and dried with anhydrous sodium sulfate for 4 h. Then, the dichloromethane was removed by vacuum distillation at 0.08 MPa and 110 °C. The remaining product of vacuum distillation was purified by silica gel column chromatography. The mobile phase of silica gel column chromatography was petroleum ether / ethyl acetate with a volume ratio of 4:1 to obtain the phenoxyethylamine collector. S3. Grind the raw ore containing sphalerite into a slurry. Adjust the pH of the slurry to 9 before zinc flotation. Without adding copper sulfate activator, add the phenoxyethylamine collector obtained in this example to the slurry at a dosage of 50 g / t. After adjusting the slurry for 2.5 min, perform zinc flotation to obtain sphalerite concentrate.

[0021] Example 3: This embodiment is an example of the collector used in the copper sulfate-free flotation of sphalerite according to the present invention. The collector is dodecylamine, which belongs to the straight-chain alkylamines shown in Formula 1, wherein R is dodecyl and has the structural formula CH3(CH2)11NH2. The specific steps are as follows: S1. According to the mass fraction, take 15 parts of lauric acid, 3 parts of ammonia, 82 parts of dimethylformamide, and 0.75 parts of Raney nickel catalyst; add lauric acid to dimethylformamide and stir to dissolve, then introduce ammonia until the mixed solution is alkaline, add Raney nickel catalyst and stir evenly, then transfer to a high-pressure reactor, seal the reactor and introduce hydrogen, adjust the reaction pressure to 2 MPa, the reaction temperature to 180℃, and carry out the reduction reaction for 8 h to obtain a mixed solution containing dodecylamine; S2. After cooling the mixed solution containing dodecylamine to room temperature, wash with deionized water until the washing liquid is neutral; then extract with petroleum ether 3 times, combine the petroleum ether extracts, and dry with anhydrous magnesium sulfate for 4 h. Then remove petroleum ether by vacuum distillation at 0.08 MPa and 120℃. Then purify the remaining product by vacuum distillation to obtain the dodecylamine collector. S3. Grind the raw ore containing sphalerite into a slurry. Adjust the pH of the slurry to 8 before zinc flotation. Without adding copper sulfate activator, add the dodecylamine collector obtained in this example to the slurry at a dosage of 40 g / t. After adjusting the slurry for 2 minutes, perform zinc flotation to obtain sphalerite concentrate.

[0022] Comparative Example 1: The difference between this comparative example and Example 1 is that the butoxypropylamine collector prepared in Example 1 is not used in the zinc flotation process, but sodium butyl xanthate is used as the sphalerite collector, and no copper sulfate activator is added.

[0023] Specifically, the raw ore containing sphalerite was ground into a slurry and then subjected to zinc flotation pretreatment in the same manner as in Example 1. During the zinc flotation process, no copper sulfate activator was added, and sodium butyl xanthate was added to the slurry as a collector. The amount of sodium butyl xanthate used in the zinc roughing was 60 g / t, the amount used in zinc scavenging I was 30 g / t, and the total amount used was 90 g / t. The remaining flotation conditions were the same as in Example 1.

[0024] Comparative Example 2: The difference between this comparative example and Example 1 is that the butoxypropylamine collector prepared in Example 1 is not used in the zinc flotation process. Instead, copper sulfate is used as an activator and ethyl xanthate is used as a collector for traditional copper sulfate activated xanthate flotation.

[0025] Specifically, the raw ore containing sphalerite was ground into a slurry and then subjected to zinc flotation pretreatment in the same manner as in Example 1. In the zinc roughing process, 150 g / t of copper sulfate and 60 g / t of ethyl xanthate were added, and in the zinc scavenging process I, 50 g / t of copper sulfate and 30 g / t of ethyl xanthate were added. The total amount of copper sulfate used was 200 g / t, and the total amount of ethyl xanthate used was 90 g / t. The remaining flotation conditions were the same as in Example 1.

[0026] Table 1. Flotation test parameters of the collectors obtained in Examples 1-3

[0027] Table 1 shows that the collectors obtained in Examples 1-3 can all achieve sphalerite flotation without the addition of copper sulfate activator. Among them, the butoxypropylamine collector obtained in Example 1 showed better flotation performance, with a Zn grade of 34.26% and a Zn recovery rate of 92.16% in the obtained zinc concentrate; the phenoxyethylamine collector obtained in Example 2 yielded a Zn grade of 30.26% in the obtained zinc concentrate and a Zn recovery rate of 89.36%; and the dodecylamine collector obtained in Example 3 yielded a Zn grade of 20.35% in the obtained zinc concentrate and a Zn recovery rate of 85.07%. These results indicate that the straight-chain alkylamines and alkoxy / phenoxy-substituted amines described in this invention can all be used as sphalerite collectors without copper sulfate activation, with alkoxy / phenoxy-substituted amines exhibiting superior collecting effect and selectivity.

[0028] Table 2. Flotation test parameters of sodium butyl xanthate in Comparative Example 1

[0029] Table 2 shows that, without the addition of copper sulfate activator, sodium butyl xanthate alone, when used as a collector, yields a Zn grade of only 3.47% in the zinc concentrate and a Zn recovery rate of only 4.99%, while the Zn grade in the tailings reaches as high as 2.32%. This result indicates that traditional xanthate-based collectors have weak collecting ability for sphalerite without copper sulfate activation, making it difficult to achieve effective enrichment of sphalerite. Table 3. Flotation test parameters of copper sulfate activated xanthate method in Comparative Example 2

[0030] Table 3 shows that the copper sulfate-activated xanthate method can achieve sphalerite flotation, with a Zn grade of 21.16% and a Zn recovery rate of 86.59%. However, this method requires the addition of an additional 200 g / t of copper sulfate activator and 90 g / t of xanthate collector, resulting in problems such as high reagent consumption, residual copper ions, and increased pressure on subsequent wastewater treatment.

[0031] As can be seen from Tables 1 to 3, compared with Comparative Example 1, the collector of the present invention significantly improves the flotation effect of sphalerite under the condition of no copper sulfate activation; compared with Comparative Example 2, the butoxypropylamine collector obtained in Example 1 of the present invention can obtain zinc concentrate with a Zn grade of 34.26% and a Zn recovery rate of 92.16% without the addition of copper sulfate activator. The flotation index is better than that of the traditional copper sulfate activated xanthate system, indicating that the collector of the present invention has strong sphalerite collecting ability, good selectivity and environmental friendliness.

[0032] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A collector for copper sulfate-free activation flotation of sphalerite, characterized in that, The active component of the collector includes a straight-chain alkylamine of Formula 1 or an alkoxy / phenoxy-substituted amine of Formula 2: Formula 1: ; Wherein, R is a straight-chain alkyl group of C12 to C18; Formula 2: ; Wherein, R1 is a C2-C4 alkyl or phenyl group, and R2 is a C2-C3 alkylene group; The collector is used to float sphalerite without the addition of copper sulfate activator.

2. The collector for copper sulfate-free flotation of sphalerite according to claim 1, characterized in that, The linear alkylamine shown in Formula 1 is selected from one or more of dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine.

3. The collector for copper sulfate-free activation flotation of sphalerite according to claim 1, characterized in that, The alkoxy / phenoxy substituted amines shown in Formula 2 are selected from one or more of ethoxyethylamine, phenoxyethylamine, and butoxypropylamine.

4. A method for preparing a collector for copper sulfate-free flotation of sphalerite as described in any one of claims 1-3, characterized in that, Including path A or path B: Path A: C12-C18 straight-chain fatty acids are mixed with ammonia and heated to the reaction temperature under the action of a catalyst. Hydrogen is then introduced to carry out a reduction reaction, resulting in a mixed solution containing straight-chain alkylamines. After cooling the mixed solution containing straight-chain alkylamines, it is washed with deionized water until neutral, and then the straight-chain alkylamines are extracted with petroleum ether. The solution is then dried with anhydrous magnesium sulfate, purified by vacuum distillation and vacuum fractionation, to obtain the straight-chain alkylamine collector shown in Formula 1. Route B: Mix alkoxy alcohol or phenoxy alcohol with ammonia, add a catalyst, and heat to the reaction temperature under pressure to carry out an amination reaction, obtaining a mixed solution containing alkoxy / phenoxy substituted amines; after cooling the mixed solution containing alkoxy / phenoxy substituted amines to room temperature, adjust the pH to 6-7 with dilute sulfuric acid, extract with dichloromethane, dry with anhydrous sodium sulfate, purify by vacuum distillation and silica gel column chromatography to obtain the alkoxy / phenoxy substituted amine collector shown in Formula 2.

5. The preparation method according to claim 4, characterized in that, In path A, the C12-C18 straight-chain fatty acids are selected from one or more of lauric acid, myristic acid, palmitic acid, and stearic acid.

6. The preparation method according to claim 1, characterized in that, The catalyst in pathway A is Raney nickel, and the amount of catalyst used is 5% to 8% of the mass of C12 to C18 straight-chain fatty acids; the reaction temperature of the reduction reaction is 180 to 220°C, the reaction pressure is 2 to 3 MPa, and the reaction time is 8 to 12 h.

7. The preparation method according to claim 1, characterized in that, In path B, the alkoxy alcohol or phenoxy alcohol is selected from one or more of ethoxyethanol, phenoxyethanol, and butoxypropanol.

8. The preparation method according to claim 1, characterized in that, The amination reaction in pathway B is carried out at a temperature of 120–150°C, a pressure of 1.5–2 MPa, and a time of 6–10 h.

9. The preparation method according to claim 1, characterized in that, The mass fraction of the dilute sulfuric acid is 10%, and the molar ratio of the alkoxy / phenoxy substituted amine to the dilute sulfuric acid is 1:1.2; the mobile phase for the silica gel column chromatography is petroleum ether / ethyl acetate with a volume ratio of 4:

1.

10. The application of a collector as described in any one of claims 1-3 in copper sulfate-free activation flotation of sphalerite, characterized in that, A collector is added to a slurry containing sphalerite, and zinc flotation is carried out without the addition of copper sulfate activator to obtain sphalerite concentrate. The pH of the slurry is adjusted to 8-10 before zinc flotation, the amount of the collector is 40-60 g / t, and the slurry is adjusted for 2-3 min after the addition of the amine collector.

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