Method for recovering precious metals from beneficiation tailings

Abstract

The application discloses a method for recovering and extracting precious metals from ore dressing tailings, and belongs to the technical field of resource recovery. The method for recovering and extracting precious metals from ore dressing tailings comprises the following steps: step (1), classifying, crushing and grinding the collected tailings, and then placing the tailings in a filter press to remove water and dry the tailings to obtain pretreated tailings; step (2), adding the pretreated tailings into a flotation reagent, and under the action of stirring and aeration, making the precious metal mineral particles adhere to the bubbles and float to the water surface to form a foam layer; step (3), collecting the foam layer to obtain a concentrate; and step (4), concentrating, water-reducing, drying and smelting the concentrate to obtain the precious metals. The method can effectively improve the recovery rate of the precious metals.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of resource recycling, and particularly relates to a method for recovering and extracting precious metals from ore dressing tailings. BACKGROUND

[0002] With the continuous growth of global demand for precious metals and the increasing depletion of mineral resources, how to efficiently recover and extract precious metals from a large amount of tailings has become an important issue in the mining industry. Precious metals such as gold and silver have wide application value in many fields such as electronics, aerospace, jewelry, etc. due to their unique physical and chemical properties. In recent years, with the progress of science and technology and the development of emerging industries, the demand for precious metals has shown a trend of increasing year by year. However, traditional mineral exploitation and beneficiation methods can only extract part of the precious metals in the ore, and a large amount of precious metals still remain in the tailings. These tailings not only occupy a large amount of land resources, but also may cause potential harm to the environment and ecological system. Therefore, recovering and extracting precious metals from tailings not only can improve the utilization rate of resources and reduce resource waste, but also can reduce environmental damage, which has important economic and environmental significance.

[0003] Patent CN 104846195 B discloses a method for recovering low-grade precious metals from ore dressing tailings. The method includes the steps of tailings raw material flotation, Nelson concentrator gravity separation, Nelson tailings oxidation roasting pretreatment, and cyanide leaching of the cinder. The tailings flotation enriches gold in the flotation concentrate, the flotation concentrate is subjected to Nelson concentrator gravity separation to recover coarse-grained gold again, the Nelson tailings are subjected to oxidation roasting pretreatment, and the cinder after treatment is subjected to cyanide leaching process to recover fine-grained gold lost in the Nelson tailings. The invention realizes the recovery of gold in stages, improves the recovery rate of gold, solves the problem of low recovery rate of precious metals using traditional process in flotation tailings, and improves the recovery rate of precious metals. Gold concentrate and iron concentrate are produced, and the comprehensive utilization rate of tailings is improved. However, there is still room for improvement in the recovery rate of precious metals. SUMMARY

[0004] The purpose of the present application is to provide a method for recovering and extracting precious metals from ore dressing tailings, which solves the technical problem of low recovery rate of precious metals in the prior art.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0006] The present application provides a method for recovering and extracting precious metals from ore dressing tailings, comprising the following steps:

[0007] Step (1): The collected tailings are classified, crushed, and ground, and then placed in a filter press to remove water and dry to obtain pretreated tailings;

[0008] Step (2): The pre-processed tailings are added to the flotation reagent, under the action of stirring and aeration, the noble metal mineral particles are attached to the bubbles and float to the water surface to form a foam layer;

[0009] Step (3): The foam layer is collected to obtain the concentrate;

[0010] Step (4): The concentrate is concentrated, water-reduced, dried, and smelted to obtain the noble metal.

[0011] Preferably, in the step (2), the flotation reagent comprises a modified collector and a composite frother.

[0012] Preferably, the preparation method of the modified collector comprises the following steps:

[0013] Q1: Magnesium chloride hexahydrate and benzonitrile are added to a container containing N,N-dimethylformamide, stirred at room temperature, then sodium hydrosulfide hydrate is added and continues to be stirred, after the reaction is completed, saturated sodium chloride and distilled water are added, extracted, dried, rotary evaporated and concentrated to obtain intermediate 1;

[0014] Q2: Ethyl bromopyruvate is added to ethanol, mixed, then added dropwise to intermediate 1, stirred at room temperature, then heated to reflux, after the reaction is completed, the pH is adjusted, stirred, extracted, dried, purified to obtain intermediate 2;

[0015] Q3: Hydrazine hydrate is slowly added to methanol containing intermediate 2, heated to reflux and stirred, after the stirring is completed, cooled, solid precipitates, suction filtered, washed to obtain intermediate 3;

[0016] Q4: Intermediate 3 and potassium hydroxide are dissolved in methanol, then carbon disulfide is slowly added, stirred at room temperature, then heated to reflux, after the reflux is completed, cooled, ice water is slowly added to the reaction solution, the pH is adjusted, solid precipitates, suction filtered, washed with water, recrystallized, dried to obtain the modified collector.

[0017] In the above process, the synthesis reaction formula of the modified collector is as follows:

[0018]

[0019] The mass spectrometry analysis result is: m / z: 261.00 (100.0%), 262.01 (12.0%), 263.00 (9.2%), 262.00 (2.7%), 264.00 (1.3%), 263.01 (1.1%).

[0020] As preferred, in the Q1, the molar ratio of magnesium chloride hexahydrate, benzonitrile and sodium hydrosulfide hydrate is (5.33-5.86):(4.85-5.34):(10.67-11.74), the stirring time at room temperature is 10-20 min, the continuous stirring time is 12-16 h, the volume ratio of saturated sodium chloride and distilled water is 7:1, cross-extraction is performed using ethyl acetate and saturated sodium chloride, and drying is performed using anhydrous sodium sulfate; in the Q2, the molar ratio of ethyl bromopyruvate and intermediate 1 is (5.33-5.86):(4.85-5.34), the stirring time at room temperature is 1-2 h, the reflux stirring time is 4-6 h, the pH is adjusted to 8-8.3, stirring is performed for 30-45 min, cross-extraction is performed using saturated sodium chloride and dichloromethane, drying is performed using anhydrous sodium sulfate, and purification is performed using a mixed solution of petroleum ether and ethyl acetate with a volume ratio of 5:1 as an eluent.

[0021] As preferred, in the Q3, the molar ratio of hydrazine hydrate and intermediate 2 is (10.9-13.1):(3.63-4.36), and the reflux stirring time is 4-6 h; in the Q4, the molar ratio of intermediate 3, potassium hydroxide and carbon disulfide is (3.09-4.64):(9.27-13.91):(7.72-11.58), the stirring time at room temperature is 30-45 min, the heating reflux time is 8-10 h, and the pH is adjusted to 5-6, and recrystallization is performed using methanol.

[0022] As preferred, the preparation method of the composite foaming agent comprises the following steps:

[0023] S1: An aqueous solution of sodium hypochlorite is added to a container, followed by the addition of 1-methylpyrazole-5-carboxylic acid, stirring at room temperature, acidification after stirring, solid precipitation, suction filtration, to obtain compound A; compound A is added to a container, and thionyl chloride is added dropwise, stirring under reflux, vacuum concentration after stirring, to obtain compound B;

[0024] S2: Pyridine-3-acetic acid methyl ester and tetrahydrofuran are added to a container, lithium bis(trimethylsilyl)amide in tetrahydrofuran is added dropwise under nitrogen protection at low temperature, stirring, then tetrahydrofuran containing compound B is added dropwise, continuous stirring after dropwise addition, addition of distilled water to quench the reaction after stirring, pH adjustment, extraction, washing, drying, vacuum filtration and concentration, purification, to obtain compound C;

[0025] S3: Compound C is added to a container, an aqueous solution of sulfuric acid is added dropwise, heated to reflux and stirred, after stirring, distilled water is added for dilution, pH is adjusted, extracted, washed, dried, concentrated by vacuum filtration, purified to obtain compound D; compound D is dissolved in methanol, sodium borohydride is added under ice bath conditions, stirred at room temperature, after stirring, concentrated under reduced pressure, adjusted pH, extracted, dried, concentrated by vacuum filtration, purified to obtain compound E;

[0026] S4: sodium hydride is added to a solution of compound E in N,N-dimethylformamide, stirred at room temperature, then an N,N-dimethylformamide solution containing iodomethane is added dropwise, continue to stir, after stirring, quench the reaction with saturated aqueous ammonium chloride solution, extract, wash, dry, concentrate by vacuum filtration, purify to obtain a composite foaming agent.

[0027] In the above process, the synthesis reaction formula of the composite foaming agent is as follows:

[0028]

[0029] The mass spectrometry result is: m / z: 251.08 (100.0%), 253.08 (32.1%), 252.09 (13.2%), 254.08 (4.5%), 252.08 (1.1%), 253.09 (1.0%).

[0030] As preferred, in S1, the amount ratio of aqueous sodium hypochlorite solution and 1-methylpyrazole-5-carboxylic acid is (24-36) mL:(2-2.5) g, the volume fraction of aqueous sodium hypochlorite solution is 10 vt%, the stirring time at room temperature is 10-12 h, and 2 mol / L hydrochloric acid is used for acidification; the amount ratio of compound A and thionyl chloride is (1-1.5) g:(5-7.5) mL, and the stirring time is 5-8 h.

[0031] As preferred, in S2, the molar ratio of pyridine-3-acetic acid methyl ester, lithium bis(trimethylsilyl)amide and compound B is (13.08-18.31):(14.33-20.06):(6.2-8.68), the low temperature is -78 to -80℃, the stirring time is 1-2 h, the continuous stirring time is 1-1.5 h, 2 mol / L hydrochloric acid is used to adjust pH=4-5, ethyl acetate is used for extraction, saturated sodium chloride is used for washing, anhydrous sodium sulfate is used for drying, and 100-200 mesh silica gel column is used for purification during purification, and the mixed solution of petroleum ether and ethyl acetate with a volume ratio of 4:1 is used as eluent.

[0032] As preferred, in the S3, the ratio of the use amount of the compound C and the aqueous sulfuric acid solution is (1-1.5)g:(5-7.5)mL, the volume fraction of the aqueous sulfuric acid solution is 50vt%, the stirring temperature under heating reflux is 90-110℃, the stirring time is 1-2h, the pH is adjusted to 7-7.2 by using 4mol / L sodium hydroxide solution; the ratio of the use amount of the compound D and sodium borohydride is (0.5-1)g:(0.16-0.32)g, the stirring time at room temperature is 1-2h, the pH is adjusted to 5-6 by using 2mol / L hydrochloric acid.

[0033] As preferred, in the S4, the molar ratio of sodium hydride and the compound E is (0.84-1.01):(0.42-0.5), the stirring time at room temperature is 10-20min, the continuous stirring time is 1-2h, the extraction is performed 3-5 times by using ethyl acetate, the washing is performed by using distilled water and saturated sodium chloride, and the drying is performed by using anhydrous sodium sulfate.

[0034] In summary, due to the adoption of the above technical solutions, the present application has the following beneficial effects:

[0035] 1. The present application firstly uses benzyl cyanide, magnesium chloride hexahydrate, ethyl bromopyruvate, hydrazine hydrate and carbon disulfide as raw materials to prepare a modified collector, and then uses 1-methylpyrazole-5-carboxylic acid, sodium hypochlorite, thionyl chloride, pyridine-3-methyl acetate and iodomethane as raw materials to prepare a composite foaming agent, so that the modified collector and the composite foaming agent can be used as flotation reagents in the beneficiation process, and the recovery efficiency of noble metals can be effectively improved.

[0036] 2. The present application uses benzyl cyanide, magnesium chloride hexahydrate, ethyl bromopyruvate, hydrazine hydrate and carbon disulfide as raw materials to prepare a modified collector, and the use of the modified collector can effectively improve the recovery efficiency of noble metals. The sulfur and nitrogen coordination atoms in the modified collector have lone pair electrons, which can form a coordination bond with the empty orbital of noble metals. The formation of this coordination bond forms a close chelation relationship between the modified collector and the noble metals. Because different metals have different binding abilities with these coordination atoms, the modified collector can exhibit high selectivity to noble metals. This selectivity promotes the effective separation of noble metals from tailings in the extraction process, while reducing the interference and extraction of other non-noble metal elements. The close coordination chelation relationship between the modified collector and the noble metals can effectively capture and extract the noble metals from the tailings, which not only improves the extraction efficiency of the noble metals, but also reduces the loss in the extraction process, thereby improving the recovery rate of the noble metals.

[0037] 3. The present application uses 1-methylpyrazole-5-carboxylic acid, sodium hypochlorite, thionyl chloride, pyridine-3-acetic acid methyl ester and iodomethane as raw materials to prepare a composite foaming agent. The nitrogen atom on the pyridine ring in the composite foaming agent has a lone pair of electrons, which can form a coordination bond with noble metal ions to form a stable complex. The presence of the complex can change the state of existence of noble metal ions in the tailings, making it easier to release and extract from the tailings, and improving the purity of noble metals. Moreover, the composite foaming agent can reduce the surface tension of the tailings suspension, increase the stability and number of bubbles, and thus increase the contact area and contact time of bubbles and tailings particles, improve the adsorption and migration efficiency of noble metal ions, and improve the extraction efficiency of noble metals. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0039] Embodiment 1

[0040] The present embodiment discloses a preparation method of a modified collector, comprising the following steps:

[0041] Q1: 11.36g of magnesium chloride hexahydrate and 5.2g of benzonitrile were added to a container containing 220mL of N,N-dimethylformamide, stirred at room temperature for 15min, then 8.3g of sodium hydrosulfide hydrate was added and continued to stir for 16h, after the reaction was completed, saturated sodium chloride and distilled water were added, the volume ratio of saturated sodium chloride to distilled water was 7:1, cross-extraction was performed using ethyl acetate and saturated sodium chloride, dried with anhydrous sodium sulfate, concentrated by rotary evaporation, and intermediate 1 was obtained;

[0042] Q2: 10.91g of ethyl bromopyruvate was added to 300mL of ethanol, mixed, then added dropwise to 7.29g of intermediate 1, stirred at room temperature for 2h, then heated to reflux for 6h, after the reaction was completed, the pH was adjusted to 8, stirred for 45min, cross-extracted with saturated sodium chloride and dichloromethane, dried with anhydrous sodium sulfate, and purified with a mixed solution of petroleum ether and ethyl acetate with a volume ratio of 5:1 as eluent to obtain intermediate 2;

[0043] Q3: 5.83g of hydrazine hydrate was slowly added to 300mL of methanol containing 9.31g of intermediate 2, heated to reflux and stirred for 6h, after stirring was completed, the mixture was cooled, and solid was precipitated, filtered, and washed to obtain intermediate 3;

[0044] Q4: 8.62 g of intermediate 3 and 6.49 g of potassium hydroxide were dissolved in 500 mL of methanol, then 7.34 g of carbon disulfide was slowly added, stirred at room temperature for 45 min, then heated to reflux for 10 h. After the reflux was completed, the reaction solution was cooled, ice water was slowly added to adjust the pH to 5, and a solid was precipitated. Filtration, water washing, recrystallization with methanol, and drying were performed to obtain the modified collector.

[0045] The embodiment discloses a preparation method of a composite foaming agent, and comprises the following steps:

[0046] S1: 30 mL of a 10 vt% sodium hypochlorite aqueous solution was added to a container, followed by the addition of 2.25 g of 1-methylpyrazole-5-carboxylic acid. Stirring was performed at room temperature for 12 h. After the stirring was completed, acidification was performed with 2 mol / L hydrochloric acid, a solid was precipitated, and filtration was performed to obtain compound A. 1.25 g of compound A was added to a container, 6.25 mL of thionyl chloride was added dropwise, and stirring was performed under reflux for 8 h. After the stirring was completed, concentration was performed under reduced pressure to obtain compound B.

[0047] S2: 2.38 g of pyridine-3-acetic acid methyl ester and 10 mL of tetrahydrofuran were added to a container. Under nitrogen protection, 10 mL of tetrahydrofuran containing 2.88 mL of lithium bis(trimethylsilyl)amide was added dropwise at-78 ℃. Stirring was performed for 2 h, then 5 mL of tetrahydrofuran containing 1.33 g of compound B was added dropwise. After the dropwise addition was completed, stirring was continuously performed for 1.5 h. After the stirring was completed, distilled water was added to quench the reaction, 2 mol / L hydrochloric acid was used to adjust the pH to 4, extraction was performed with ethyl acetate, washing was performed with saturated sodium chloride, drying was performed with anhydrous sodium sulfate, concentration was performed under reduced pressure, and purification was performed with a silica gel column with a particle size of 100-200 mesh. A mixed solution of petroleum ether and ethyl acetate with a volume ratio of 4:1 was used as an eluent to purify compound C.

[0048] S3: 1.25 g of compound C was added to a container, 6.25 mL of a 50 vt% sulfuric acid aqueous solution was added dropwise, and stirring was performed under reflux at 110 ℃ for 2 h. After the stirring was completed, distilled water was added for dilution, 4 mol / L sodium hydroxide solution was used to adjust the pH to 7, extraction was performed, washing was performed, drying was performed, concentration was performed under reduced pressure, and purification was performed to obtain compound D. 0.75 g of compound D was dissolved in 15 mL of methanol, 0.24 g of sodium borohydride was added under ice bath conditions, stirring was performed at room temperature for 2 h, after the stirring was completed, concentration was performed under reduced pressure, 2 mol / L hydrochloric acid was used to adjust the pH to 5, extraction was performed, drying was performed, concentration was performed under reduced pressure, and purification was performed to obtain compound E.

[0049] S4: 0.033 g of sodium hydride was added to 1 mL of N, N-dimethylformamide solution containing 0.11 g of compound E, after stirring at room temperature for 15 min, 0.2 mL of N, N-dimethylformamide solution containing 0.015 g of iodomethane was added dropwise, and stirring was continued for 2 h, after the end of stirring, the reaction was quenched with saturated aqueous ammonium chloride solution, extracted with ethyl acetate 5 times, washed with distilled water, saturated sodium chloride, dried with anhydrous sodium sulfate, concentrated by vacuum filtration, purified to obtain a composite frother.

[0050] The embodiment discloses a method for recovering and extracting precious metals from beneficiation tailings, comprising the following steps:

[0051] Step (1): The collected tailings are classified, crushed, and ground, and then placed in a filter press to remove water and dry to obtain pretreated tailings;

[0052] Step (2): The pretreated tailings are added to a flotation reagent containing a modified collector and a composite frother, under the action of stirring and aeration, the precious metal mineral particles are attached to the gas bubbles and float to the water surface to form a froth layer;

[0053] Step (3): The froth layer is collected to obtain a concentrate;

[0054] Step (4): The concentrate is concentrated, shrunk, dried and smelted to obtain the precious metal.

[0055] Example 2

[0056] The embodiment discloses a preparation method of a modified collector, comprising the following steps:

[0057] Q1: 10.82 g of magnesium chloride hexahydrate and 4.95 g of benzonitrile are added to a container containing 220 mL of N, N-dimethylformamide, after stirring at room temperature for 15 min, 7.9 g of sodium hydrosulfide hydrate is added and stirring is continued for 16 h, after the reaction is completed, saturated sodium chloride and distilled water are added, the volume ratio of saturated sodium chloride to distilled water is 7:1, cross-extraction is performed using ethyl acetate and saturated sodium chloride, drying is performed using anhydrous sodium sulfate, rotary evaporation is performed to concentrate, and intermediate 1 is obtained;

[0058] Q2: 10.39 g of ethyl bromopyruvate is added to 300 mL of ethanol, after mixing, it is added dropwise to 6.94 g of intermediate 1, stirring is performed at room temperature for 2 h, and then heating reflux is performed for 6 h, after the reaction is completed, the pH is adjusted to 8, stirring is performed for 45 min, cross-extraction is performed using saturated sodium chloride and dichloromethane, drying is performed using anhydrous sodium sulfate, a mixed solution of petroleum ether and ethyl acetate with a volume ratio of 5:1 is used as an eluent for purification, and intermediate 2 is obtained;

[0059] Q3: 5.29 g of hydrazine hydrate was slowly added to 300 mL of methanol containing 8.46 g of intermediate 2, heated to reflux and stirred for 6 h. After stirring, the reaction was cooled, and a solid was precipitated. Filtration, washing, and drying yielded intermediate 3.

[0060] Q4: 6.89 g of intermediate 3 and 5.19 g of potassium hydroxide were dissolved in 500 mL of methanol, and then 5.87 g of carbon disulfide was slowly added. After stirring at room temperature for 45 min, the reaction was heated to reflux for 10 h. After the reaction was completed, ice water was slowly added to the reaction solution, and the pH was adjusted to 5. A solid was precipitated, and filtration, washing with water, recrystallization with methanol, and drying yielded the modified collector.

[0061] The present embodiment discloses a preparation method of a composite foaming agent, comprising the following steps:

[0062] S1: 24 mL of 10 vol% sodium hypochlorite aqueous solution was added to a container, followed by the addition of 2.5 g of 1-methylpyrazole-5-carboxylic acid. The mixture was stirred at room temperature for 12 h. After stirring, the reaction was acidified with 2 mol / L hydrochloric acid, and a solid was precipitated. Filtration yielded compound A. 1.5 g of compound A was added to a container, and 7.5 mL of thionyl chloride was added dropwise. The mixture was stirred at reflux for 8 h. After stirring, the reaction was concentrated under reduced pressure to obtain compound B.

[0063] S2: 1.98 g of pyridine-3-acetic acid methyl ester and 10 mL of tetrahydrofuran were added to a container. Under nitrogen protection, 10 mL of 2.4 mL of lithium bis(trimethylsilyl)amide in tetrahydrofuran was added dropwise at -78°C. After stirring for 2 h, 5 mL of 1.11 g of compound B in tetrahydrofuran was added dropwise. After the addition was completed, the mixture was stirred for 1.5 h. After stirring, the reaction was quenched with distilled water, and the pH was adjusted to 4 with 2 mol / L hydrochloric acid. Extraction was performed with ethyl acetate, and the organic phase was washed with saturated sodium chloride, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. During purification, a silica gel column with a particle size of 100-200 mesh was used. A mixture of petroleum ether and ethyl acetate with a volume ratio of 4:1 was used as the eluent to obtain compound C.

[0064] S3: 1.5 g of compound C was added to a container, and 5 mL of 50 vol% sulfuric acid aqueous solution was added dropwise. The mixture was heated to reflux and stirred at 110°C for 2 h. After stirring, the reaction was diluted with distilled water, and the pH was adjusted to 7 with 4 mol / L sodium hydroxide solution. After extraction, washing, and drying, the mixture was concentrated under reduced pressure. Purification yielded compound D. 0.5 g of compound D was dissolved in 15 mL of methanol, and 0.32 g of sodium borohydride was added under ice bath conditions. The mixture was stirred at room temperature for 2 h. After stirring, the reaction was concentrated under reduced pressure, and the pH was adjusted to 5 with 2 mol / L hydrochloric acid. After extraction, drying, and concentration under reduced pressure, purification yielded compound E.

[0065] S4: 0.03 g of sodium hydride was added to 1 mL of N,N-dimethylformamide solution containing 0.12 g of compound E, stirred at room temperature for 15 min, then 0.2 mL of N,N-dimethylformamide solution containing 0.015 g of iodomethane was added dropwise, and stirring was continued for 2 h. After stirring was completed, the reaction was quenched with saturated aqueous ammonium chloride solution, extracted with ethyl acetate 5 times, washed with distilled water and saturated sodium chloride, dried over anhydrous sodium sulfate, concentrated by vacuum filtration, and purified to obtain a composite frother.

[0066] The embodiment discloses a method for recovering and extracting precious metals from ore dressing tailings, comprising the following steps:

[0067] Step (1): The collected tailings are classified, crushed, and ground, and then placed in a filter press to remove water and dry to obtain pretreated tailings;

[0068] Step (2): The pretreated tailings are added to a flotation reagent containing a modified collector and a composite frother, and under the action of stirring and aeration, the precious metal mineral particles are attached to the gas bubbles and float to the water surface to form a froth layer;

[0069] Step (3): The froth layer is collected to obtain a concentrate;

[0070] Step (4): The concentrate is concentrated, shrunk, dried, and smelted to obtain the precious metal.

[0071] Example 3

[0072] The embodiment discloses a preparation method of a modified collector, comprising the following steps:

[0073] Q1: 11.9 g of magnesium chloride hexahydrate and 5.45 g of benzonitrile are added to a container containing 220 mL of N,N-dimethylformamide, stirred at room temperature for 15 min, then 8.69 g of sodium hydrosulfide hydrate is added and stirring is continued for 16 h. After the reaction is completed, saturated sodium chloride and distilled water are added, the volume ratio of saturated sodium chloride to distilled water is 7:1, cross-extraction is performed using ethyl acetate and saturated sodium chloride, drying is performed over anhydrous sodium sulfate, rotary evaporation is performed for concentration, and intermediate 1 is obtained.

[0074] Q2: 11.43 g of ethyl bromopyruvate is added to 300 mL of ethanol, mixed, then added dropwise to 7.64 g of intermediate 1, stirred at room temperature for 2 h, then heated to reflux for 6 h. After the reaction is completed, the pH is adjusted to 8, stirring is performed for 45 min, cross-extraction is performed using saturated sodium chloride and dichloromethane, drying is performed over anhydrous sodium sulfate, a mixed solution of petroleum ether and ethyl acetate with a volume ratio of 5:1 is used as an eluent for purification, and intermediate 2 is obtained.

[0075] Q3: 6.36 g of hydrazine hydrate was slowly added to 300 mL of methanol containing 10.16 g of intermediate 2, heated to reflux and stirred for 6 h. After stirring, the reaction was cooled, and a solid was precipitated. Filtration, washing, and drying yielded intermediate 3.

[0076] Q4: 10.35 g of intermediate 3 and 7.79 g of potassium hydroxide were dissolved in 500 mL of methanol, and then 8.8 g of carbon disulfide was slowly added. After stirring at room temperature for 45 min, the reaction was heated to reflux for 10 h. After the reaction was completed, ice water was slowly added to the reaction solution, and the pH was adjusted to 5. A solid was precipitated, and filtration, washing with water, recrystallization with methanol, and drying yielded the modified collector.

[0077] The present embodiment discloses a preparation method of a composite foaming agent, comprising the following steps:

[0078] S1: 36 mL of 10 vol% sodium hypochlorite aqueous solution was added to a container, followed by the addition of 2 g of 1-methylpyrazole-5-carboxylic acid. The mixture was stirred at room temperature for 12 h. After stirring, the reaction was acidified with 2 mol / L hydrochloric acid, and a solid was precipitated. Filtration yielded compound A. 1 g of compound A was added to a container, and 5 mL of thionyl chloride was added dropwise. The mixture was stirred at reflux for 8 h. After stirring, the reaction was concentrated under reduced pressure to obtain compound B.

[0079] S2: 2.77 g of pyridine-3-acetic acid methyl ester and 10 mL of tetrahydrofuran were added to a container. Under nitrogen protection, 10 mL of lithium bis(trimethylsilyl)amide in tetrahydrofuran was added dropwise at -78°C. After stirring for 2 h, 5 mL of tetrahydrofuran containing 1.55 g of compound B was added dropwise. After the addition was completed, the mixture was stirred for another 1.5 h. After stirring, the reaction was quenched with distilled water, and the pH was adjusted to 4 with 2 mol / L hydrochloric acid. Extraction was performed with ethyl acetate, and the organic phase was washed with saturated sodium chloride, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. During purification, a silica gel column with a particle size of 100-200 mesh was used. A mixture of petroleum ether and ethyl acetate with a volume ratio of 4:1 was used as the eluent to obtain compound C.

[0080] S3: 1 g of compound C was added to a container, and 7.5 mL of 50 vol% sulfuric acid aqueous solution was added dropwise. The mixture was heated to reflux and stirred at 110°C for 2 h. After stirring, the reaction was diluted with distilled water, and the pH was adjusted to 7 with 4 mol / L sodium hydroxide solution. After extraction, washing, and drying, the mixture was concentrated under reduced pressure. Purification yielded compound D. 1 g of compound D was dissolved in 15 mL of methanol, and 0.16 g of sodium borohydride was added under ice bath conditions. The mixture was stirred at room temperature for 2 h. After stirring, the reaction was concentrated under reduced pressure, and the pH was adjusted to 5 with 2 mol / L hydrochloric acid. After extraction, drying, and concentration under reduced pressure, purification yielded compound E.

[0081] S4: 0.036 g of sodium hydride was added to 1 mL of N, N-dimethylformamide solution containing 0.1 g of compound E, stirred at room temperature for 15 min, then 0.2 mL of N, N-dimethylformamide solution containing 0.015 g of iodomethane was added dropwise, and stirring was continued for 2 h. After stirring was completed, the reaction was quenched with saturated aqueous ammonium chloride solution, extracted with ethyl acetate 5 times, washed with distilled water and saturated sodium chloride, dried over anhydrous sodium sulfate, concentrated by vacuum filtration, and purified to obtain a composite frother.

[0082] The present embodiment discloses a method for recovering and extracting precious metals from beneficiation tailings, comprising the following steps:

[0083] Step (1): The collected tailings are classified, crushed, and ground, and then placed in a filter press to remove water and dry to obtain pretreated tailings;

[0084] Step (2): The pretreated tailings are added to a flotation reagent containing a modified collector and a composite frother, and under the action of stirring and aeration, the precious metal mineral particles adhere to the gas bubbles and float to the water surface to form a froth layer;

[0085] Step (3): The froth layer is collected to obtain a concentrate;

[0086] Step (4): The concentrate is concentrated, water-reduced, dried, and smelted to obtain precious metals.

[0087] Example 4

[0088] The present embodiment discloses a method for preparing a modified collector, comprising the following steps:

[0089] Q1: 11.09 g of magnesium chloride hexahydrate and 5.08 g of benzonitrile were added to a container containing 220 mL of N, N-dimethylformamide, stirred at room temperature for 15 min, then 8.1 g of sodium hydrosulfide hydrate was added and stirring was continued for 16 h. After the reaction was completed, saturated sodium chloride and distilled water were added in a volume ratio of 7:1, cross-extraction was performed using ethyl acetate and saturated sodium chloride, dried over anhydrous sodium sulfate, concentrated by rotary evaporation, and intermediate 1 was obtained.

[0090] Q2: 10.65 g of ethyl bromopyruvate was added to 300 mL of ethanol, mixed, and then added dropwise to 7.12 g of intermediate 1, stirred at room temperature for 2 h, and then heated to reflux for 6 h. After the reaction was completed, the pH was adjusted to 8, stirred for 45 min, cross-extracted with saturated sodium chloride and dichloromethane, dried over anhydrous sodium sulfate, and purified using a mixed solution of petroleum ether and ethyl acetate in a volume ratio of 5:1 as an eluent to obtain intermediate 2.

[0091] Q3: 5.56 g of hydrazine hydrate was slowly added to 300 mL of methanol containing 8.89 g of intermediate 2, heated to reflux and stirred for 6 h. After stirring, the reaction was cooled, and a solid was precipitated. Filtration, washing, and drying yielded intermediate 3.

[0092] Q4: 7.76 g of intermediate 3 and 7.14 g of potassium hydroxide were dissolved in 500 mL of methanol, and then 8.07 g of carbon disulfide was slowly added. After stirring at room temperature for 45 min, the reaction was heated to reflux for 10 h. After the reaction was completed, ice water was slowly added to the reaction solution, and the pH was adjusted to 5. A solid was precipitated, and filtration, washing with water, recrystallization with methanol, and drying yielded the modified collector.

[0093] The present embodiment discloses a preparation method of a composite foaming agent, comprising the following steps:

[0094] S1: 33 mL of 10 vol% sodium hypochlorite aqueous solution was added to a container, followed by the addition of 2.1 g of 1-methylpyrazole-5-carboxylic acid. The mixture was stirred at room temperature for 12 h. After stirring, the reaction was acidified with 2 mol / L hydrochloric acid, and a solid was precipitated. Filtration yielded compound A. 1.1 g of compound A was added to a container, and 5.5 mL of thionyl chloride was added dropwise. The mixture was stirred at reflux for 8 h. After stirring, the reaction was concentrated under reduced pressure to obtain compound B.

[0095] S2: 2.18 g of pyridine-3-acetic acid methyl ester and 10 mL of tetrahydrofuran were added to a container. Under nitrogen protection, 10 mL of lithium bis(trimethylsilyl)amide in tetrahydrofuran was added dropwise at -78°C. After stirring for 2 h, 5 mL of tetrahydrofuran containing 1.22 g of compound B was added dropwise. After the addition was completed, the mixture was stirred for another 1.5 h. After stirring, the reaction was quenched with distilled water, and the pH was adjusted to 4 with 2 mol / L hydrochloric acid. Extraction was performed with ethyl acetate, and the organic phase was washed with saturated sodium chloride, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. Purification was performed on a silica gel column with 100-200 mesh, and a mixture of petroleum ether and ethyl acetate (4:1, by volume) was used as the eluent to obtain compound C.

[0096] S3: 1.1 g of compound C was added to a container, and 5.5 mL of 50 vol% sulfuric acid aqueous solution was added dropwise. The mixture was heated to reflux and stirred at 110°C for 2 h. After stirring, the reaction was diluted with distilled water, and the pH was adjusted to 7 with 4 mol / L sodium hydroxide solution. Extraction, washing, and drying were performed, and the mixture was concentrated under reduced pressure. Purification yielded compound D. 0.6 g of compound D was dissolved in 15 mL of methanol, and 0.2 g of sodium borohydride was added under ice bath conditions. The mixture was stirred at room temperature for 2 h. After stirring, the reaction was concentrated under reduced pressure, the pH was adjusted to 5 with 2 mol / L hydrochloric acid, and the mixture was extracted, dried, and concentrated under reduced pressure. Purification yielded compound E.

[0097] S4: 0.032 g of sodium hydride was added to 1 mL of N, N-dimethylformamide solution containing 0.12 g of compound E, stirred at room temperature for 15 min, then 0.2 mL of N, N-dimethylformamide solution containing 0.015 g of iodomethane was added dropwise, and stirring was continued for 2 h. After stirring was completed, the reaction was quenched with saturated aqueous ammonium chloride solution, extracted with ethyl acetate 5 times, washed with distilled water, saturated sodium chloride, dried with anhydrous sodium sulfate, concentrated by vacuum filtration, and purified to obtain a composite frother.

[0098] The present embodiment discloses a method for recovering and extracting precious metals from mineral processing tailings, comprising the following steps:

[0099] Step (1): The collected tailings are classified, crushed, and ground, and then placed in a filter press to remove water and dry to obtain pretreated tailings;

[0100] Step (2): The pretreated tailings are added to a flotation reagent containing a modified collector and a composite frother, and under the action of stirring and aeration, the precious metal mineral particles adhere to the gas bubbles and float to the water surface to form a foam layer;

[0101] Step (3): The foam layer is collected to obtain a concentrate;

[0102] Step (4): The concentrate is concentrated, shrunk, dried, and smelted to obtain precious metals.

[0103] Comparative Example 1: Comparative Example 1 is compared with Example 1. In the preparation of the modified collector of Comparative Example 1, ethyl bromopyruvate is not added, and other conditions remain unchanged.

[0104] Comparative Example 2: Comparative Example 2 is compared with Example 1. In the preparation of the composite frother of Comparative Example 2, pyridine-3-methyl acetate is not added, and other conditions remain unchanged.

[0105] Comparative Example 3: Comparative Example 3 is compared with Example 1. In the recovery and extraction process of Comparative Example 3, the modified collector is not added, and other conditions remain unchanged.

[0106] Comparative Example 4: Comparative Example 4 is compared with Example 1. In the recovery and extraction process of Comparative Example 4, the composite frother is not added, and other conditions remain unchanged.

[0107] According to the methods of Examples 1-4 and Comparative Examples 1-4, the precious metals in the mineral processing tailings are recovered and extracted, the content of heavy metals is tested according to GB / T 17418.7-2010, the recovery rate of precious metals is calculated, and the test results are shown in Table 1:

[0108] Table 1

[0109]

[0110] From the test results in Table 1, it can be seen that the precious metal has excellent recovery rate by the method of Examples 1-4. From the comparison of Comparative Example 1 and Examples 1-4, it can be seen that the addition of ethyl bromopyruvate can make the precious metal in the tailings have excellent recovery rate; from the comparison of Comparative Example 2 and Examples 1-4, it can be seen that the addition of pyridine-3-acetic acid methyl ester can make the precious metal in the tailings have excellent recovery rate; from the comparison of Comparative Example 3 and Examples 1-4, it can be seen that the addition of modified collector can make the precious metal in the tailings have excellent recovery rate; from the comparison of Comparative Example 4 and Examples 1-4, it can be seen that the addition of composite foaming agent can make the precious metal in the tailings have excellent recovery rate.

[0111] The above description is only for the preferred embodiments of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

[0112] The above disclosed preferred embodiments of the present application are only used to help explain the present application. The preferred embodiments do not describe all the details, nor limit the present application to the specific embodiments. Obviously, according to the content of the present application, many modifications and changes can be made. The present application selects and specifically describes these embodiments in order to better explain the principles and practical application of the present application, so that the skilled person in the art can well understand and utilize the present application. The present application is limited by the claims and the entire scope and equivalents thereof.

Claims

1. A method for recovering and extracting precious metals from beneficiation tailings, characterized in that, The method comprises the following steps: Step (1): the collected tailings are classified, crushed, and ground, and then placed in a filter press to remove water and dry to obtain pretreated tailings; Step (2): the pretreated tailings are added to a flotation reagent, under the action of stirring and aeration, the particles of the noble metal minerals are attached to the bubbles and float to the water surface to form a froth layer; Step (3): the froth layer is collected to obtain a concentrate; Step (4): the concentrate is concentrated, water-reduced, dried, and smelted to obtain noble metals; In the step (2), the flotation reagent comprises a modified collector and a composite frother; The modified collector has the following structural formula: ； The composite frother has the following structural formula: ； The modified collector is prepared from benzyl cyanide, magnesium chloride hexahydrate, ethyl bromopyruvate, hydrazine hydrate, and carbon disulfide; and the composite frother is prepared from 1-methylpyrazole-5-carboxylic acid, sodium hypochlorite, thionyl chloride, pyridine-3-acetic acid methyl ester, and iodomethane; The preparation method of the modified collector comprises the following steps: The method comprises the following steps: Q1: magnesium chloride hexahydrate and benzyl cyanide are added to a container containing N,N-dimethylformamide, stirred at room temperature, then sodium hydrosulfide hydrate is added and continues to be stirred, after the reaction is completed, saturated sodium chloride and distilled water are added, extracted, dried, concentrated by rotary evaporation, and an intermediate 1 is obtained; Q2: ethyl bromopyruvate is added to ethanol, mixed, then added dropwise to the intermediate 1, stirred at room temperature, then heated to reflux, after the reaction is completed, the pH is adjusted, stirred, extracted, dried, purified, and an intermediate 2 is obtained; Q3: hydrazine hydrate is slowly added to methanol containing the intermediate 2, heated to reflux and stirred, after the stirring is completed, cooled, a solid is precipitated, suction filtered, washed, and an intermediate 3 is obtained; Q4: the intermediate 3 and potassium hydroxide are dissolved in methanol, then carbon disulfide is slowly added, stirred at room temperature, heated to reflux, after the reflux is completed, cooled, ice water is slowly added to the reaction solution, the pH is adjusted, a solid is precipitated, suction filtered, washed with water, recrystallized, and dried to obtain the modified collector; In the Q1, the molar ratio of the magnesium chloride hexahydrate, the benzyl cyanide, and the sodium hydrosulfide hydrate is (5.33-5.86):(4.85-5.34):(10.67-11.74), the stirring time at room temperature is 10-20 min, the continuous stirring time is 12-16 h, the volume ratio of the saturated sodium chloride to the distilled water is 7:1, cross-extraction is performed using ethyl acetate and saturated sodium chloride, and drying is performed using anhydrous sodium sulfate; in the Q2, the molar ratio of the ethyl bromopyruvate to the intermediate 1 is (5.33-5.86):(4.85-5.34), the stirring time at room temperature is 1-2 h, the reflux stirring time is 4-6 h, the pH is adjusted to 8-8.3, the stirring time is 30-45 min, cross-extraction is performed using saturated sodium chloride and dichloromethane, drying is performed using anhydrous sodium sulfate, and purification is performed using a mixed solution of petroleum ether and ethyl acetate with a volume ratio of 5:1 as an eluent; In the Q3, the molar ratio of hydrazine hydrate and intermediate 2 is (10.9-13.1):(3.63-4.36), the reflux stirring time is 4-6h; in the Q4, the molar ratio of intermediate 3, potassium hydroxide and carbon disulfide is (3.09-4.64):(9.27-13.91):(7.72-11.58), the stirring time at room temperature is 30-45min, the heating reflux time is 8-10h, the pH is adjusted to 5-6, and recrystallization is performed with methanol.

2. The method of recovering and extracting precious metals from beneficiation tailings according to claim 1, characterized in that, The preparation method of the composite foaming agent comprises the following steps: S1: sodium hypochlorite aqueous solution is added to a container, then 1-methylpyrazole-5-carboxylic acid is added, stirring is performed at room temperature, after stirring, acidification is performed, a solid is precipitated, filtration is performed, compound A is obtained; compound A is added to a container, thionyl chloride is added dropwise, stirring is performed under reflux, after stirring, concentration is performed under reduced pressure, and compound B is obtained; S2: pyridine-3-acetic acid methyl ester and tetrahydrofuran are added to a container, under nitrogen protection, under low-temperature conditions, lithium bis(trimethylsilyl)amide-containing tetrahydrofuran is added dropwise, stirring is performed, then compound B-containing tetrahydrofuran is added dropwise, after dropwise addition, continuous stirring is performed, after stirring, distilled water is added to quench the reaction, pH is adjusted, extraction is performed, washing is performed, drying is performed, concentration is performed under reduced pressure, and purification is performed, thereby obtaining compound C; S3: compound C is added to a container, sulfuric acid aqueous solution is added dropwise, heating reflux stirring is performed, after stirring, distilled water is added for dilution, pH is adjusted, extraction is performed, washing is performed, drying is performed, concentration is performed under reduced pressure, and purification is performed, thereby obtaining compound D; compound D is dissolved in methanol, sodium borohydride is added under ice bath conditions, stirring is performed at room temperature, after stirring, concentration is performed under reduced pressure, pH is adjusted, extraction is performed, drying is performed, concentration is performed under reduced pressure, and purification is performed, thereby obtaining compound E; S4: sodium hydride is added to a solution of compound E in N,N-dimethylformamide, after stirring at room temperature, iodomethane-containing N,N-dimethylformamide solution is added dropwise, continuous stirring is performed, after stirring, the reaction is quenched with saturated ammonium chloride aqueous solution, extraction is performed, washing is performed, drying is performed, concentration is performed under reduced pressure, and purification is performed, thereby obtaining the composite foaming agent.

3. The method of recovering and extracting precious metals from beneficiation tailings according to claim 2, characterized in that, In the S1, the amount ratio of sodium hypochlorite aqueous solution and 1-methylpyrazole-5-carboxylic acid is (24-36)mL:(2-2.5)g, the volume fraction of the sodium hypochlorite aqueous solution is 10vt%, the stirring time at room temperature is 10-12h, and acidification is performed with 2mol / L hydrochloric acid; the amount ratio of compound A and thionyl chloride is (1-1.5)g:(5-7.5)mL, and the stirring time is 5-8h.

4. The method of recovering and extracting precious metals from beneficiation tailings according to claim 2, characterized in that, In the S2, the molar ratio of pyridine-3-acetic acid methyl ester, lithium bis(trimethylsilyl)amide and compound B is (13.08-18.31):(14.33-20.06):(6.2-8.68), the low temperature is -78 to -80℃, the stirring time is 1-2h, the continuous stirring time is 1-1.5h, the pH is adjusted to 4-5 by 2mol / L hydrochloric acid, extraction is performed by ethyl acetate, washing is performed by saturated sodium chloride, drying is performed by anhydrous sodium sulfate, and purification is performed by a silica gel column with 100-200 mesh, and a mixed solution of petroleum ether and ethyl acetate with a volume ratio of 4:1 is used as an eluent.

5. The method of recovering and extracting precious metals from mineral processing tailings according to claim 2, characterized in that, In the S3, the ratio of compound C and sulfuric acid aqueous solution is (1-1.5)g:(5-7.5)mL, the volume fraction of sulfuric acid aqueous solution is 50vt%, the stirring temperature is 90-110℃, the stirring time is 1-2h, the pH is adjusted to 7-7.2 by 4mol / L sodium hydroxide solution, the ratio of compound D and sodium borohydride is (0.5-1)g:(0.16-0.32)g, the stirring time is 1-2h at room temperature, and the pH is adjusted to 5-6 by 2mol / L hydrochloric acid.

6. The method of recovering and extracting precious metals from mineral processing tailings according to claim 2, characterized in that, In the S4, the molar ratio of sodium hydride and compound E is (0.84-1.01):(0.42-0.5), the stirring time is 10-20min at room temperature, the continuous stirring time is 1-2h, extraction is performed by ethyl acetate for 3-5 times, washing is performed by distilled water and saturated sodium chloride, and drying is performed by anhydrous sodium sulfate.

Images