A cascaded beneficiation process for precious metals

Abstract

The present invention belongs to the field of mineral processing technology, and particularly relates to a cascaded mineral processing technology for precious metals. The method adopts a combination of multi-stage flash flotation and preferential flotation. Under the action of a trace amount of special reagents, the method uses the technical means of grinding and selecting to carry out cascade recovery of precious metal minerals with different floatability. While avoiding the loss of the monomer-dissociated precious metal mineral particles due to over-grinding, the target minerals with good floatability and early monomer dissociation are preferentially recovered as much as possible to ensure their quality, and at the same time, the interference of uneven embedded particle size on the flotation process of precious metals is reduced, realizing the technical concept of "collecting as much as possible, collecting as early as possible, and increasing environmental protection". Compared with the prior art, the present invention effectively avoids the loss of the monomer-dissociated precious metal mineral particles due to over-grinding, and reduces the workload of subsequent selection operations. It not only improves the flotation efficiency of the target minerals, reduces the loss of precious metal minerals in tailings, but also improves the comprehensive utilization rate of resources.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral processing, and in particular relates to a cascade mineral processing technology for precious metals. Background Art

[0002] The flotation process refers to the process in which the pulp flows through various operations during flotation, and gradually floats through each designed process to achieve the separation and enrichment of different mineral components. It is a flotation production process composed of different flotation operations (grinding operation, roughing operation, concentrating operation, scavenging operation, etc.). According to the different process structures and reagent systems, the flotation process can be divided into different structural forms such as positive flotation, reverse flotation, mixed flotation, priority flotation, open-circuit flotation, closed-circuit flotation, and equal flotation, which are collectively referred to as conventional flotation processes. When facing actual ores, it is necessary to select appropriate flotation processes according to the natural properties of the selected minerals and the corresponding reagent systems. For example, when facing ores with coarse particle size of target minerals, high content of valuable minerals, and good mineral floatability, the priority flotation process is usually used to sort out the target minerals in sequence. When facing polymetallic minerals with target minerals in the form of aggregate impregnation, the mixed flotation process is usually selected to float out the closely coexisting useful minerals together.

[0003] However, although the conventional flotation process can meet the selection requirements of most ores, when faced with precious metal ores with unevenly distributed particle sizes, the shortcomings of conventional flotation, such as long process, complex selection process, difficult operation, and weak adaptability, can no longer meet the requirements of precious metal beneficiation. Moreover, with the continuous exploitation of precious metal mineral resources in my country, the ore properties of precious metal mines are becoming increasingly poor, fine, mixed, and scattered. The same ore in different deposits or even the same minerals in different ore bodies in the same deposit also show different floatability differences. The conventional flotation process is difficult to adapt to the current mining companies' requirements for the beneficiation of precious metal ores. Therefore, current mineral processing technology workers need to develop new technologies and processes suitable for precious metal beneficiation based on the differences in particle size, floatability, and floating speed between different minerals and the same minerals, promote the separation effect of useful minerals in complex ores, and improve the economic and social benefits of mines.

[0004] As one of the flotation processes for precious metals, flash flotation has been applied in many places. From the perspective of currently disclosed technologies, either flash flotation is used alone (such as patent CN202110354018.1), or the ore is ground first and then classified, and the coarse particles in the classification are subjected to flash flotation, and the fine particles are subjected to conventional flotation (such as patent CN202111434603.9 and patent 201810970721.3), but the collectors used are still traditional yellow medicine and / or black medicine; and the above operations generally do not have the optimization of multiple grinding. This leads to high environmental pressure on the existing process, low recovery rate of precious metals, and serious waste of resources. Therefore, how to break through the technical bottleneck of the existing flotation process and further improve the recovery rate of precious metals is one of the important problems that need to be solved urgently. Summary of the invention

[0005] The purpose of the present invention is to overcome the defect that it is difficult to achieve efficient directional enrichment for the recovery of precious metals in the existing process, and to provide a precious metal gradient beneficiation process with stable operation, simple use, strong adaptability and low environmental pressure, which can improve the grade and recovery rate of precious metals while solving the shortcomings of the existing technology, and realize branching processing of multi-level products.

[0006] The present invention adopts the following technical solutions to achieve the above purpose:

[0007] The present invention discloses a cascaded beneficiation process for precious metals, which comprises two parts: flash flotation and priority flotation. Tailings obtained from the flash flotation are used as raw materials to enter the priority flotation for flotation. The cascaded beneficiation process comprises at least two flash flotations.

[0008] Preferably, in the cascade beneficiation process, the number of flash flotation is 3 times.

[0009] As a preferred embodiment, a cascaded beneficiation process for precious metals and a method for using the same in the present invention specifically comprises the following steps:

[0010] S1. Primary flash flotation: crush the raw ore and grind it to -0.074mm, accounting for 60-70%, adjust the pulp concentration between 10-45%, then add precious metal collector for flotation, the flotation time is 30-60s, the obtained concentrate is the primary flash flotation concentrate, and the obtained tailings are the primary flash flotation tailings;

[0011] S2. Secondary flash flotation: The primary flash flotation tailings obtained in S1 are concentrated and re-grinded to -0.074mm, accounting for 80-90%, and then water is added to adjust the pulp concentration between 10 and 45%, and a precious metal collector is added. After sufficient stirring, secondary flash flotation is performed, and the flotation time is 30 to 60 seconds. The resulting concentrate is the secondary flash flotation concentrate, and the resulting tailings are the secondary flash flotation tailings;

[0012] S3. Three-stage flash flotation: The secondary flash flotation tailings obtained in S2 are concentrated and re-grinded to -0.038mm, accounting for 90-100%, and then water is added to adjust the pulp concentration between 10 and 45%, and a precious metal collector is added. After sufficient stirring, three-stage flash flotation is carried out, and the flotation time is 30 to 60s. The concentrate obtained is the three-stage flash flotation concentrate, and the tailings obtained are the three-stage flash flotation tailings;

[0013] S4. Priority flotation: pH adjuster, dispersant, inhibitor and precious metal collector are added to the tertiary flash flotation tailings obtained in S3 respectively, and flotation is carried out after sufficient stirring. The flotation time is 2 to 15 minutes. The obtained concentrate enters the concentration operation, and the obtained tailings enter the scavenging operation. The middlings obtained from the concentration operation are returned to the previous concentration operation in sequence, and the concentrates obtained from the scavenging operation are returned to the previous scavenging operation in sequence; the concentrate obtained from the concentration operation is the comprehensive concentrate, and the tailings obtained from the scavenging operation are the final tailings.

[0014] The reasons why the present invention adopts three-stage flotation combined with regrinding and priority flotation process are as follows: ① The precious metal minerals with different embedded particle sizes are accurately classified by the method of graded grinding-graded flotation, and the precious metal minerals with different embedded particle sizes are graded ground and graded recovered, which effectively avoids the loss of the precious metal mineral particles that have been monomerically dissociated due to over-grinding, while reducing the workload of subsequent selection operations, reducing the number of selection operations, and can flexibly determine the amount of separation according to the properties of the material, increasing the flexibility of the process and reducing the working pressure of the entire flotation process. ② Multi-stage flash flotation is carried out before conventional flotation. Through the capture effect of trace reagents, the target minerals with good floatability and early monomer dissociation can be preferentially recovered and their quality can be guaranteed as much as possible while avoiding the weakening of floatability differences by large doses of reagents. This can not only improve the flotation efficiency of the target minerals, but also ensure the product quality of the target minerals and reduce the loss of precious metal minerals in tailings. ③ Through the synergistic effect between flash flotation and conventional flotation, the interference of uneven embedded particle size on the flotation process of precious metals can be significantly reduced, and the action time of reagents can be prolonged, the efficiency of reagents can be increased, and the flotation efficiency of some precious metal carrier minerals with poor floatability can be improved. It can also greatly improve the recovery rate of precious metal minerals and improve the adaptability and stability of precious metal beneficiation technology.

[0015] Preferably, the present invention provides a cascaded beneficiation process for precious metals and a method for using the same, wherein the precious metal refers to an ore and / or solid waste and / or smelting slag containing at least one of copper, gold, silver, copper, ruthenium, rhodium, palladium, osmium, iridium and platinum, and is more preferably an ore containing precious metals.

[0016] Preferably, in the present invention, a cascade beneficiation process for precious metals and a method for using the same, the collector is prepared by the following process:

[0017] According to weight, 10-30 parts of alcohol organic matter, 1-10 parts of phosphorus trichloride, 10-100 parts of organic solvent, 1-20 parts of elemental sulfur, 1-20 parts of triethylamine, 3-10 parts of strong acid or strong base are prepared; alcohol organic matter, phosphorus trichloride, organic solvent, elemental sulfur, triethylamine, strong acid or strong base are prepared; firstly, the prepared alcohol organic matter, phosphorus trichloride and organic solvent are uniformly mixed to obtain a mixed solution A;

[0018] Add the prepared elemental sulfur and triethylamine into the mixed solution A, and then stir and mix thoroughly;

[0019] Then, 3-10 parts of the prepared strong acid or strong base are added, preferably 9-10 parts of the strong base are added.

[0020] As a further preferred method, 15 to 30 parts of alcohol organic matter, 5 to 10 parts of phosphorus trichloride, 50 to 100 parts of organic solvent, 6 to 15 parts of elemental sulfur, 6 to 15 parts of triethylamine, and 3 to 10 parts of strong acid or strong base are prepared by weight; alcohol organic matter, phosphorus trichloride, organic solvent, elemental sulfur, triethylamine, strong acid or strong base are prepared. As a further preferred method, the mass ratio of elemental sulfur to triethylamine is 1:1.

[0021] As a further preference, the organic solvent is at least one of pyrimidine, dichloromethane and ether, preferably dichloromethane.

[0022] As further preferred, the strong acid is hydrochloric acid; the strong base is at least one of ammonia water, sodium hydroxide and potassium hydroxide, preferably sodium hydroxide.

[0023] As a further preference, the alcohol organic substance is at least one of ethanol, n-propanol, isopropanol, n-butanol and isobutanol, preferably isobutanol.

[0024] Preferably, in the cascaded beneficiation process for precious metals and the method for using the cascaded beneficiation process, the flotation time of each stage of flash flotation is 30 to 40 seconds.

[0025] Preferably, in the present invention, a cascaded beneficiation process for precious metals and a method of using the same, the flash flotation only adds precious metal collectors without adding any other flotation agents.

[0026] Preferably, in the cascaded beneficiation process for precious metals and the use method thereof of the present invention, the slurry concentration of the flash flotation is between 10 and 45%, and more preferably between 25 and 35%.

[0027] Preferably, in the cascaded beneficiation process for precious metals and the method for using the same, in S1, the grinding fineness is -0.074 mm, accounting for 60-70%, and more preferably 65%.

[0028] Preferably, in the cascaded beneficiation process for precious metals and the method for using the same, in S1, the amount of precious metal collector used is 10-50 g / t, preferably 25-35 g / t.

[0029] Preferably, in the cascaded beneficiation process for precious metals and the method for using the same, in S2, the grinding fineness is -0.074 mm, accounting for 80-90%, and more preferably 85%.

[0030] Preferably, in the cascaded beneficiation process for precious metals and the method for using the same, in S2, the amount of precious metal collector used is 10-50 g / t, preferably 25-35 g / t.

[0031] Preferably, in the cascaded beneficiation process for precious metals and the method for using the same, in S3, the grinding fineness is -0.038 mm, accounting for 90-100%, and more preferably 95%.

[0032] Preferably, in the cascaded beneficiation process for precious metals and the method for using the same, in S3, the amount of precious metal collector used is 10-50 g / t, preferably 25-35 g / t.

[0033] Preferably, in the cascaded beneficiation process for precious metals and the method for using the same, in S4, the number of cleaning steps is at least once, more preferably twice; the number of scavenging steps is at least once, more preferably twice.

[0034] As a preferred embodiment, in the cascaded beneficiation process of precious metals and the use method thereof, in S4, the inhibitor comprises at least one of lime, water glass, salinized water glass, acidified water glass, sodium sulfite, sodium bisulfite, sodium dithionite, sodium pyrosulfite, zinc sulfate and formaldehyde. The dosage of the inhibitor is 50-500 g / t.

[0035] Preferably, in the cascaded beneficiation process of precious metals and its use method of the present invention, in S4, the pH adjuster includes at least one of sodium carbonate, sodium bicarbonate, hydrochloric acid, sulfuric acid, and sodium hydroxide. During the preferential flotation, the pH value of the system is 6-8.

[0036] Preferably, in the cascaded beneficiation process of precious metals and the use method thereof of the present invention, in S4, the dispersant comprises at least one of sodium hexametaphosphate and sodium fluorosilicate, and the amount of the dispersant is 0-300 g / t.

[0037] Preferably, in a cascaded beneficiation process for precious metals and a method for using the same, in S4, during roughing, the amount of collector is 50-300 g / t, the amount of inhibitor is 50-500 g / t, the amount of dispersant is 0-300 g / t; and the pH is controlled at 6-8.

[0038] Compared with the current precious metal beneficiation process, the technical solution of the present invention brings the following beneficial effects:

[0039] ① The present invention accurately classifies precious metal minerals with different embedded particle sizes, and classifies and recovers the precious metal minerals with different embedded particle sizes by means of classifying grinding-classifying flotation, thereby effectively avoiding the loss of the precious metal mineral particles that have been dissociated into monomers due to over-grinding, while reducing the workload of subsequent concentration operations, reducing the number of concentration operations, and flexibly determining the amount of separation according to the properties of the material, thereby increasing the flexibility of the process and reducing the working pressure of the entire flotation process.

[0040] ② The present invention adopts the technical concept of "collecting all that should be collected, collecting as early as possible, and increasing income by environmental protection". Multi-stage flash flotation is carried out before conventional flotation. Through the capture effect of trace reagents, while avoiding the weakening of floatability differences by a large amount of reagents, the target minerals with good floatability and early monomer dissociation are preferentially recovered as much as possible to ensure their quality, which not only improves the flotation efficiency of the target minerals, reduces the loss of precious metal minerals in tailings, but also improves the comprehensive utilization rate of resources.

[0041] ③ The present invention significantly reduces the interference of uneven embedded particle size on the flotation process of precious metals through the synergistic effect between flash flotation and conventional flotation, and can adapt to the slow flotation performance of some target minerals. It not only improves the flotation efficiency of some precious metal carrier minerals with poor floatability and realizes the cascade recovery of complex precious metal ores, but also greatly improves the recovery rate of precious metal minerals and improves the adaptability and stability of precious metal beneficiation technology.

[0042] ④ The present invention can improve the recovery rate of precious metal minerals while reducing the amount of collectors and reducing environmental pollution as much as possible through the synergistic effect between three-stage flash flotation and conventional flotation, and with the optimized collectors and collection parameters. Moreover, after the optimization of the present invention, all collectors are non-xantholytic and / or black drug collectors; the pollution to the environment is relatively small. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is the ore dressing flow chart of Example 1;

[0044] Figure 2 This is the mineral processing flow chart of Comparative Example 1. DETAILED DESCRIPTION

[0045] The following examples are intended to further illustrate the content of the present invention, but are not intended to limit the protection scope of the claims of the present invention.

[0046] (1) Preparation of collector:

[0047] In a container equipped with a stirrer, 30 parts of isobutanol, 10 parts of phosphorus trichloride and 100 parts of dichloromethane were added, and after sufficient stirring until complete reaction (reaction time was 2 hours), 11 parts of elemental sulfur were added at one time, and 11 parts of triethylamine were added dropwise. After sufficient stirring for 8 hours until complete reaction, 10 parts of sodium hydroxide were added, and the solution was stirred until it became a brown liquid to obtain the collector, which was recorded as implementation reagent 1.

[0048] In a container equipped with a stirrer, 15 parts of isobutanol, 5 parts of phosphorus trichloride and 50 parts of dichloromethane were added, and after sufficient stirring until complete reaction (reaction time was 1 hour), 6 parts of elemental sulfur were added at one time, and 6 parts of triethylamine were added dropwise. After further sufficient stirring for 6 hours until complete reaction, 6 parts of sodium hydroxide were added, and the mixture was stirred until the solution became a yellow-brown liquid to obtain the collector, which was recorded as implementation reagent 2.

[0049] (2) Ore raw materials

[0050] The mineral raw material was taken from a gold mine in Hengyang, Hunan, and the original ore contained 2.5g / t of gold. Phase analysis results showed that the main gold-containing mineral in the mineral was native gold, other gold-containing minerals were mainly pyrite, and the gangue minerals were mainly quartz, calcite, amphibole, chlorite, etc. The flotation collector was implementation reagent 1 or implementation reagent 2 or as described in the following examples and comparative examples, and the inhibitor and dispersant were water glass.

[0051] Example 1

[0052] 1000g of raw ore was added to a ball mill and ground to -0.074mm, accounting for 65%. It was taken out and water was added to adjust the pulp concentration to 35%. Then 30g / t of reagent 1 was added. After stirring for 3min, a primary flash flotation operation was performed. The flotation time was 40s. The resulting concentrate was recorded as concentrate I. After the tailings were concentrated, they were added to a ball mill and ground to -0.074mm, accounting for 85%. It was taken out and water was added to adjust the pulp concentration to 35%. Then 30g / t of reagent 1 was added. After stirring for 3min, a secondary flash flotation operation was performed. The flotation time was 40s. The resulting concentrate was recorded as concentrate II. After the tailings were concentrated, they were added to a ball mill and ground to -0.038m m accounts for 95%, and water is added to adjust the pulp concentration to 35%, then 30g / t of implementing reagent 1 is added, and three-level flash flotation operations are carried out after stirring for 3min, and the flotation time is 40s. The obtained concentrate is recorded as concentrate III; after the three flash flotations are completed, 150g / t of water glass and 150g / t of implementing reagent 1 are added respectively, and each reagent is stirred for 3min before roughing operation, and the roughing time is 8min. The obtained roughing concentrate is subjected to two blank selections to obtain concentrate IV; the selected middlings are returned to the previous operation in sequence, and the obtained tailings are subjected to two blank scavenging operations, and the obtained scavenged concentrates are returned to the previous flotation operation in sequence. The experimental process is shown in Figure 1 , the experimental results are shown in Table 1.

[0053] Example 2

[0054] The other conditions are consistent with those in Example 1, except that the collector used is the implementation reagent 2. The experimental results obtained are shown in Table 1.

[0055] Example 3

[0056] Other conditions are consistent with those of Example 1, except that the flash flotation operation is performed only twice (i.e., the first stage flash flotation and the second stage flash flotation are used). The experimental results are shown in Table 1.

[0057] Comparative Example 1

[0058] 1000 g of raw ore (the composition is consistent with that in Example 1) was added to a ball mill and directly ground to -0.038 mm, accounting for 95%. The ore was taken out and water was added to adjust the pulp concentration to 35%. Then 150 g / t of water glass was added and stirred for 3 min. Then 240 g / t of reagent 1 was added and stirred for 3 min before roughing. The roughing time was 15 min. The obtained roughing concentrate was blanked twice, and the selected middlings were sequentially returned to the previous operation. The obtained tailings were blanked twice, and the obtained scavenged concentrates were sequentially returned to the previous flotation operation. The experimental process is shown in FIG. Figure 2 , the experimental results are shown in Table 1.

[0059] Comparative Example 2

[0060] Other conditions are consistent with those in Example 1, except that the flash flotation operation is performed only once. The experimental results are shown in Table 1.

[0061] Comparative Example 3

[0062] The other conditions are consistent with those in Example 1, except that the grinding fineness of the first-stage flash flotation is 30-40%, the grinding fineness of the second-stage flash flotation is 40-50%, and the grinding fineness of the third-stage flash flotation is 50-60%. The experimental results are shown in Table 1.

[0063] Comparative Example 4

[0064] The other conditions are consistent with those in Example 1, except that the grinding fineness of the three flash flotations is above 95%. The experimental results are shown in Table 1.

[0065] Comparative Example 5

[0066] The other conditions were consistent with those in Example 1, except that the flotation time for the three flash flotations was 90 s. The experimental results are shown in Table 1.

[0067] Comparative Example 6

[0068] The other conditions were consistent with those in Example 1, except that the flotation time for the three flash flotations was 15 s. The experimental results are shown in Table 1.

[0069] Comparative Example 7

[0070] The other processes and dosages are consistent with those in Example 1 of the present invention, except that ethyl xanthate is used as the collector. The experimental results obtained are shown in Table 1.

[0071] Comparative Example 8

[0072] The other processes and dosages are consistent with those in Example 1 of the present invention, except that butyl ammonium black medicine is used as the collector. The experimental results obtained are shown in Table 1.

[0073] Comparative Example 9

[0074] The other processes and dosages are consistent with those in Example 1 of the present invention, except that mercaptobenzothiazole is used as the collector. The experimental results obtained are shown in Table 1.

[0075] Table 1 Comparative experimental results of various embodiments

[0076]

[0077]

[0078]

[0079] It can be seen from the experimental results obtained in Example 1 and Comparative Example 1 that the total recovery rate of gold in the concentrate obtained by the technical solution disclosed in the present invention is 80.98%, and the total recovery rate of gold obtained by the conventional beneficiation process is 73.41%. By comparing the two results, it can be seen that the gold recovery rate obtained by the technical solution disclosed in the present invention is significantly higher than the gold recovery rate obtained by conventional flotation. In addition, compared with the conventional beneficiation process, the technical solution disclosed in the present invention significantly reduces the interference of uneven embedded particle size on the flotation process of precious metals, effectively avoids the loss of precious metal mineral particles that have been monomerically dissociated due to over-grinding, and while preferentially recovering and ensuring the quality of the target minerals with good floatability and early monomer dissociation as much as possible, the workload of subsequent selection operations is reduced, and the amount of separation can be flexibly determined according to the properties of the material, which increases the flexibility of the process, reduces the working pressure of the entire flotation process, and not only improves the flotation efficiency of the target mineral, reduces the loss of precious metal minerals in tailings, but also improves the comprehensive utilization rate of resources. By comparing Comparative Examples 2, 3, 4, 5, 6 with Example 1 of the present invention, it can be seen that the design of the process and process parameters of the present invention also has a great influence on the recovery rate of gold. It can be seen from comparative examples 7, 8, 9 and Example 1 of the present invention that when the process and process parameters are the same, the collector developed by the present invention has a more superior collecting effect.

Claims

1. A cascade beneficiation process for precious metals, characterized in that: The steps include: S1. Primary flash flotation: crush the raw ore and grind it to -0.074 mm, accounting for 60-70%, adjust the pulp concentration between 10-45%, then add precious metal collector for flotation, the flotation time is 30-60s, the obtained concentrate is the primary flash flotation concentrate, and the obtained tailings are the primary flash flotation tailings; S2. Secondary flash flotation: The primary flash flotation tailings obtained in S1 are concentrated and re-grinded to -0.074 mm, accounting for 80-90%, and then water is added to adjust the pulp concentration between 10-45%, and precious metal collectors are added. After sufficient stirring, secondary flash flotation is carried out, and the flotation time is 30-60s. The obtained concentrate is the secondary flash flotation concentrate, and the obtained tailings are the secondary flash flotation tailings; S3. Three-stage flash flotation: The two-stage flash flotation tailings obtained in S2 are concentrated and re-grinded to -0.038 mm, accounting for 90-100%. Then water is added to adjust the pulp concentration between 10-45%, and precious metal collectors are added. After sufficient stirring, three-stage flash flotation is carried out. The flotation time is 30-60s. The obtained concentrate is the three-stage flash flotation concentrate, and the obtained tailings are the three-stage flash flotation tailings. S4. Priority flotation: pH adjuster, dispersant, inhibitor and precious metal collector are added to the three-stage flash flotation tailings obtained in S3, and the roughing is carried out after sufficient stirring. The flotation time is 2-15 minutes. The concentrate obtained enters the concentration operation, and the tailings obtained enter the scavenging operation. The middlings obtained from the concentration operation are returned to the previous concentration operation in sequence, and the concentrates obtained from the scavenging operation are returned to the previous scavenging operation in sequence; the concentrate obtained from the concentration operation is the comprehensive concentrate, and the tailings obtained from the scavenging operation are the final tailings; The noble metal collector is prepared by the following process: According to weight, 10-30 parts of alcohol organic matter, 1-10 parts of phosphorus trichloride, 10-100 parts of organic solvent, 1-20 parts of elemental sulfur, 1-20 parts of triethylamine, and 3-10 parts of strong acid or strong base are prepared; alcohol organic matter, phosphorus trichloride, organic solvent, elemental sulfur, triethylamine, strong acid or strong base are prepared; first, the prepared alcohol organic matter, phosphorus trichloride, and organic solvent are uniformly mixed to obtain a mixed solution A; Add the prepared elemental sulfur and triethylamine into the mixed solution A, and then stir and mix thoroughly; Then add 3-10 parts of the prepared strong acid or strong base; The slurry concentration of the flash flotation is between 10 and 45%; In S1, the grinding fineness is -0.074 mm accounting for 60-70%; In S1, the dosage of precious metal collector is 10-50 g / t; In S2, the grinding fineness is -0.074 mm accounting for 80-90%; In S2, the dosage of precious metal collector is 10-50g / t; In S3, the grinding fineness is -0.038 mm accounting for 90-100%; In S3, the dosage of precious metal collector is 10-50g / t; In S4, the number of selections is at least once, and the number of scans is at least once; In S4, the inhibitor includes at least one of lime, water glass, salted water glass, acidified water glass, sodium sulfite, sodium bisulfite, sodium dithionite, sodium pyrosulfite, zinc sulfate, and formaldehyde; the dosage of the inhibitor is 50-500 g / t; In S4, the pH adjuster includes at least one of sodium carbonate, sodium bicarbonate, hydrochloric acid, sulfuric acid, and sodium hydroxide; In S4, the dispersant includes at least one of sodium hexametaphosphate and sodium fluorosilicate; the amount of the dispersant is 0-300 g / t.

2. The cascade beneficiation process for precious metals according to claim 1, characterized in that: The precious metal refers to an ore and / or solid waste and / or smelting slag containing at least one precious metal of copper, gold, silver, copper, ruthenium, rhodium, palladium, osmium, iridium and platinum.

3. The cascade beneficiation process for precious metals according to claim 1, characterized in that: By weight, 15-30 parts of alcohol organic matter, 5-10 parts of phosphorus trichloride, 50-100 parts of organic solvent, 6-15 parts of elemental sulfur, 6-15 parts of triethylamine, and 3-10 parts of strong acid or strong base are prepared; alcohol organic matter, phosphorus trichloride, organic solvent, elemental sulfur, triethylamine, strong acid or strong base are prepared.

4. The cascade beneficiation process for precious metals according to claim 1, characterized in that: The mass ratio of elemental sulfur to triethylamine is 1:1; The organic solvent is at least one of pyrimidine, dichloromethane and ether; The strong acid is hydrochloric acid; the strong base is at least one of ammonia, sodium hydroxide, and potassium hydroxide; The alcohol organic substance is at least one of ethanol, n-propanol, isopropanol, n-butanol and isobutanol.

5. The cascade beneficiation process for precious metals according to claim 1, characterized in that: The flotation time of each stage of flash flotation is 30-40s; the flash flotation only adds precious metal collectors and does not add any other flotation reagents.

6. A cascaded beneficiation process for precious metals according to claim 1, characterized in that: In S4, during roughing, the amount of collector is 50-300 g / t, the amount of inhibitor is 50-500 g / t, and the amount of dispersant is 0-300 g / t; the pH is controlled at 6-8.

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