Process for recovering valuable metals from zinc kiln dust

Abstract

The application provides a method for recycling valuable metals in zinc kiln slag, which comprises the following steps: coarsely crushing the zinc kiln slag into 3-5 mm crushed materials, adopting a ball milling plus rod milling mode to crush the zinc kiln slag into fine materials with 75-80% of the fine materials being 0.074 mm, adopting a roughing and cleaning flotation process to preliminarily separate the carbon and obtain carbon concentrates and mixed ores, adopting a roughing, cleaning and scavenging flotation process with the middlings sequentially returning for three times to obtain silver concentrates, and enriching the valuable metals in the zinc kiln slag in the silver concentrates for recycling. The method of the application realizes the recycling of the carbon concentrates and the valuable metals in the zinc kiln slag, overcomes the disadvantages that the conventional beneficiation process is difficult to effectively separate and enrich the valuable metals in the zinc kiln slag, and the pyro-process wastes resources, and simultaneously has the beneficial effects of a short flotation process and easy operation.

Description

Technical Field

[0001] This application relates to the field of kiln slag recycling technology, and in particular to a method for recovering valuable metals from zinc kiln slag. Background Technology

[0002] The hydrometallurgical zinc smelting process generates a large amount of zinc leaching residue. To recover metals such as lead and zinc from this residue, the conventional method involves adding a certain proportion of coke and lime, and then using a rotary kiln for high-temperature reducing atmosphere roasting to recover the volatile metals. However, this roasting process only recovers volatile metals like lead and zinc, while most of the non-volatile metals such as gold, silver, and iron in the leaching residue are further enriched in the rotary kiln slag. Kiln slag is a secondary resource with enormous potential. Because the slag becomes semi-molten during high-temperature roasting, many valuable elements exist in metallic or alloy states, or form various compounds. Furthermore, after water quenching following roasting, the slag has considerable hardness, making the recovery of valuable components challenging. Conventional beneficiation processes, such as magnetic separation and direct flotation of valuable metals, are insufficient for effectively separating and enriching these metals. Alternatively, the high carbon content in the slag can be utilized by employing pyrometallurgical methods to roast the slag at high temperatures and recover valuable metals. However, this method not only causes the silver metal in the zinc kiln slag to volatilize with the flue gas during the roasting process, but also fails to recover the carbon powder in the zinc kiln slag, resulting in a waste of resources. Summary of the Invention

[0003] This application provides a method for recovering valuable metals from zinc kiln slag, which solves the problems that conventional mineral processing processes cannot effectively separate and enrich valuable metals from zinc kiln slag and that pyrometallurgical processes waste resources.

[0004] This application provides a method for recovering valuable metals from zinc kiln slag, comprising the following steps:

[0005] a) The zinc kiln slag is coarsely crushed into 3-5mm pieces and then dry ball-milled to obtain coarse material with a grinding fineness of ~0.074mm accounting for 35-40%;

[0006] b) The coarse material is subjected to dry rod milling to obtain fine material with a grinding fineness of ~0.074 mm accounting for 75-80%;

[0007] c) Prepare a raw ore slurry with a concentration of 35-40% from the fine materials;

[0008] d) Add diesel and No. 2 oil to the raw ore slurry, and use a flotation process of roughing and cleaning to pre-select carbon to obtain carbon concentrate and mixed ore;

[0009] e) The mixed ore is prepared into a mixed slurry with a concentration of 30-35%, alkali is added to adjust the pH to 6.8-7.5, and collectors, activators and frothers are added. A flotation process of one roughing, two cleaning and three scavenging with sequential return of the ore is adopted to obtain silver concentrate.

[0010] The method described in this application has the following beneficial effects:

[0011] 1) The carbon concentrate in the kiln slag is pre-flotated using a roughing and refining process to separate the carbon concentrate. This not only reduces the workload of subsequent flotation, but also allows the separated carbon concentrate to be used as fuel, thus achieving resource utilization and having the beneficial effect of saving energy.

[0012] 2) In this application, the flotation process of one roughing, two cleaning, and three scavenging stages followed by sequential return of the ore concentrate to the mixed ore obtained after pre-selection of carbon can effectively enrich valuable metals such as silver in the kiln slag into the silver concentrate, reducing the waste of valuable metals.

[0013] 3) The reagents used in the flotation process in this application are inexpensive and readily available, which has the beneficial effect of saving production costs. In addition, the flotation process of this application is short and easy to operate.

[0014] Optionally, for step d):

[0015] During the roughing process, the amount of diesel added is 280-320 g / t, and the amount of No. 2 oil used is 300-400 g / t.

[0016] The carbon middlings obtained from the fine-refinement process are combined with the carbon roughing middlings obtained from the roughing process to obtain a mixed ore.

[0017] Optionally, the collector is one or more of ethyl thiocyanate, butyl xanthate, pentosan xanthate, or butyl ammonium black powder.

[0018] Optionally, the foaming agent is one or more of No. 2 oil, eucalyptus oil, camphor oil, or methyl isobutyl methanol.

[0019] Optionally, the activator is one or more of copper sulfate, sodium sulfide, sodium hydrosulfide, and ethylenediamine phosphate;

[0020] The alkali is one or more of sodium carbonate, calcium hydroxide, potassium carbonate, sodium bicarbonate, and ammonia water.

[0021] Optionally, for step e):

[0022] In the roughing process, copper sulfate and sodium sulfide are added as activators, pentoxamic acid and butylammonium black powder are added as collectors, and No. 2 oil is added as a foaming agent.

[0023] The dosage of copper sulfate is 800-1200 g / t, the dosage of sodium sulfide is 1500-2500 g / t, the dosage of pentyroflavin is 300-400 g / t, the dosage of butylammonium black powder is 300-350 g / t, and the dosage of No. 2 oil is 300-350 g / t.

[0024] Optionally, for step e):

[0025] In the first selection process, sodium sulfide was added as an activator, and pentoxamic acid and butylated black powder were added as collectors.

[0026] The dosage of sodium sulfide is 100-200 g / t, the dosage of pentyroxen is 50-75 g / t, and the dosage of butylammonium black powder is 35-45 g / t.

[0027] In the second selection, pentoflavonoids and butylammonium phosphate were added as collectors;

[0028] The dosage of pendimethalin is 40-55 g / t, and the dosage of butylammonium black powder is 25-35 g / t.

[0029] Optionally, for step e):

[0030] In the first sweep, pentoxamic acid and butylammonium black powder were added as collectors;

[0031] The dosage of pendimethalin is 100-120 g / t, and the dosage of butaniloxane is 100-120 g / t.

[0032] In the second sweep, pentoxamic acid and butylated phthalate were added as collectors;

[0033] The dosage of pendimethalin is 50-60 g / t, and the dosage of butaniloxane is 40-50 g / t.

[0034] In the third sweep, pentoflavonoids and butylated phthalate were added as collectors;

[0035] The dosage of pendimethalin is 30-50 g / t, and the dosage of butylammonium black powder is 20-30 g / t.

[0036] Optionally, the mixed slurry is further subjected to ultrasonic treatment before step e).

[0037] Optionally, the ultrasonic treatment includes:

[0038] The mixed slurry is added to a mixing device and stirred at a speed of 100-120 rpm. At the same time, the mixed slurry is treated with ultrasonic waves at frequencies of 24 kHz, 36 kHz and 42 kHz for 0.5-1 h.

[0039] This application provides a method for recovering valuable metals from zinc kiln slag. The method involves coarsely crushing the zinc kiln slag into 3-5mm pieces, then using a ball mill followed by a rod mill to further pulverize the slag to a fine powder of approximately 0.074mm (75-80%). A flotation process consisting of a roughing and a cleaning stage is then employed to pre-separate carbon concentrate and mixed ore. Finally, a flotation process involving one roughing, two cleaning, and three scavenging stages with sequential return of the ore concentrate is used to obtain silver concentrate. The valuable metals from the zinc kiln slag are then concentrated in the silver concentrate for recovery. This method effectively recovers both carbon concentrate and valuable metals from zinc kiln slag, overcoming the drawbacks of conventional beneficiation processes that struggle to effectively separate and concentrate valuable metals from zinc kiln slag, as well as the resource waste inherent in pyrometallurgical processes. Furthermore, it offers the advantages of a short flotation process and ease of operation. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a closed-loop flotation process diagram for recovering valuable metals from zinc kiln slag, provided as an embodiment of this application. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this application.

[0043] like Figure 1 As shown, this application provides a method for recovering valuable metals from zinc kiln slag, comprising the following steps:

[0044] a) The zinc kiln slag is coarsely crushed into 3-5mm pieces and then dry ball-milled to obtain coarse material with a grinding fineness of ~0.074mm accounting for 35-40%;

[0045] In this application, zinc kiln slag is coarsely crushed into 3-5mm pieces to facilitate subsequent re-crushing. The coarse crushing can be carried out by jaw crusher, impact crusher (inertial cone crusher), or compression crusher.

[0046] In one feasible implementation of this application, after obtaining the rough material, a passivation operation is further performed, the passivation operation including:

[0047] Add the coarse material to a stirring device containing a passivating agent, wherein the volume ratio of coarse material to passivating agent is 1:1 to 1:1.5, and stir at 45 to 50°C (stirring speed is 100 to 120 rpm) for 0.5 to 1.2 hours.

[0048] After stirring, filter the material and vacuum dry the filtered coarse material at 50°C to recover the solvent and obtain the dried coarse material.

[0049] The passivating agent is a heavy oil petroleum ether solution with a concentration of 8-15% wt, prepared by dissolving heavy oil in petroleum ether (boiling range 60-90℃).

[0050] In this application, since zinc kiln slag contains a large amount of carbon powder, its porous nature makes it easy for valuable metals such as silver in zinc kiln slag to be adsorbed during flotation, resulting in a decrease in the enrichment of valuable metals and affecting the recovery of valuable metals. The purpose of passivating the coarse material is to adsorb the heavy oil in the passivating agent into the pores of the carbon powder to reduce the adsorption of carbon powder. In addition, the hydrophobicity of heavy oil also helps the flotation of carbon concentrate. During the passivation process, a petroleum ether solution of heavy oil is used. In this non-polar organic solution, the ionization of valuable metal ions can be avoided, preventing the loss of valuable metals due to the passivation operation. Moreover, under these passivation conditions, the adsorption of metals by carbon powder can also be avoided.

[0051] b) The coarse material is subjected to dry rod milling to obtain fine material with a grinding fineness of ~0.074 mm accounting for 75-80%;

[0052] In this application, a rod mill is used to further crush coarse material into fine material. During the material crushing process of the rod mill, the material is crushed mainly by compression through the line-to-line contact between the steel rods. Furthermore, there are gaps between the steel rods, resulting in uniform particle size of the crushed product and reducing over-crushing.

[0053] In addition, when using a rod mill to grind the coarse material into fine material, after the coarse material undergoes a passivation process, heavy oil will adhere to the surface of the coarse material. Because heavy oil is hydrophobic, it will cause ores containing valuable metals to float together with carbon during the pre-flotation carbon operation, resulting in a high content of valuable metals in the carbon concentrate. This will affect the subsequent flotation process and reduce the recovery grade of valuable metals. When the material is crushed again by rod milling, this method can remove the heavy oil adhering to the surface of the coarse material through crushing, thereby eliminating the drawback of the presence of heavy oil affecting the flotation.

[0054] c) Prepare a raw ore slurry with a concentration of 35-40% from the fine materials;

[0055] In this application, the concentration of the raw ore pulp is 35-40%, which is beneficial for carbon flotation.

[0056] d) Add diesel and No. 2 oil to the raw ore slurry, and use a flotation process of roughing and cleaning to pre-select carbon to obtain carbon concentrate and mixed ore;

[0057] In this application, carbon is first floated, which can reduce the adsorption of valuable metals by carbon in the flotation process and help improve the grade of valuable metals in the subsequent process. Carbon itself has good floatability. Diesel oil is used as a collector for carbon, and No. 2 oil is used as a frother. Both are inexpensive and readily available, which can effectively collect carbon by flotation while reducing flotation costs.

[0058] e) The mixed ore is prepared into a mixed slurry with a concentration of 30-35%, alkali is added to adjust the pH to 6.8-7.5, and collectors, activators and frothers are added. A flotation process of one roughing, two cleaning and three scavenging with sequential return of the ore is adopted to obtain silver concentrate.

[0059] In this application, the main purpose of flotation in the mixed ore is to extract valuable metals. Therefore, the concentration of the pulp should not be too high, otherwise the grade of valuable metals in the metal concentrate obtained after flotation will be too low. This application adopts a flotation process of one roughing, two cleaning, and three scavenging with sequential return of the concentrate for the mixed ore, which can effectively enrich the valuable metals in the mixed ore and improve the recovery rate of valuable metals.

[0060] The method described in this application has the following beneficial effects:

[0061] 1) The carbon concentrate in the kiln slag is pre-flotated using a roughing and refining process to separate the carbon concentrate. This not only reduces the workload of subsequent flotation, but also allows the separated carbon concentrate to be used as fuel, thus achieving resource utilization and having the beneficial effect of saving energy.

[0062] 2) In this application, the flotation process of one roughing, two cleaning, and three scavenging of the mixed ore obtained after pre-selection of carbon can effectively enrich valuable metals such as silver in the kiln slag into silver concentrate, thereby reducing the waste of valuable metals.

[0063] 3) The reagents used in the flotation process in this application are inexpensive and readily available, which has the beneficial effect of saving production costs. In addition, the flotation process of this application is short and easy to operate.

[0064] Optionally, for step d):

[0065] During the roughing process, the amount of diesel added is 280-320 g / t, and the amount of No. 2 oil used is 300-400 g / t.

[0066] The carbon middlings obtained from the fine-refinement process are combined with the carbon roughing middlings obtained from the roughing process to obtain a mixed ore.

[0067] In this application, diesel oil and No. 2 oil are added in two stages during the roughing process to ensure a more uniform distribution of diesel oil and No. 2 oil in the slurry. The roughing and cleaning times should ideally be 4–6 minutes. Too short a time can lead to incomplete carbon flotation, resulting in a lower carbon recovery rate, while too long a time can cause carbon to adsorb valuable metals, affecting metal recovery.

[0068] Optionally, the collector is one or more of ethyl thiocyanate, butyl xanthate, pentosan xanthate, or butyl ammonium black powder.

[0069] In this application, the collector can change the hydrophobicity of the mineral surface, causing the floating mineral particles to adhere to the air bubbles, which facilitates mineral flotation. Since the valuable metals in zinc kiln slag mostly exist in the form of sulfur-containing compounds, the above-mentioned collector can better combine with the metal mineral particles in the mixed ore.

[0070] Optionally, the foaming agent is one or more of No. 2 oil, eucalyptus oil, camphor oil, or methyl isobutyl methanol.

[0071] In this application, the frother can reduce the surface tension of water to form foam, so that the air bubbles in the aerated flotation slurry can adhere to the selectively floating mineral particles. Adding the frother can effectively float and collect minerals.

[0072] Optionally, the activator is one or more of copper sulfate, sodium sulfide, sodium hydrosulfide, and ethylenediamine phosphate;

[0073] The alkali is one or more of sodium carbonate, calcium hydroxide, potassium carbonate, sodium bicarbonate, and ammonia water.

[0074] In this application, the sulfides in the zinc kiln slag ore, namely silver sulfide, chalcopyrite, pyrite, and sphalerite, are mainly separated in a solid solution structure, with relatively tight bonding, small particle size, and difficult dissociation. An activator is added to activate the iron sulfide and zinc, thereby improving the silver recovery rate.

[0075] Because the kiln slag adsorbs acidic substances such as sulfur dioxide, the mixed slurry is often acidic. The acidic pH is unfavorable to the metal ores in the flotation kiln slag. Adding alkali can adjust the pH of the slurry to improve the recovery rate of metal ores.

[0076] Optionally, for step e):

[0077] In the roughing process, copper sulfate and sodium sulfide are added as activators, pentoxamic acid and butylammonium black powder are added as collectors, and No. 2 oil is added as a foaming agent.

[0078] The dosage of copper sulfate is 800-1200 g / t, the dosage of sodium sulfide is 1500-2500 g / t, the dosage of pentyroflavin is 300-400 g / t, the dosage of butylammonium black powder is 300-350 g / t, and the dosage of No. 2 oil is 300-350 g / t.

[0079] In this application, the reagents are added in two stages during flotation to ensure that they are fully dispersed in the slurry.

[0080] Optionally, for step e):

[0081] In the first selection process, sodium sulfide was added as an activator, and pentoxanone and butylammonium black powder were added as collectors.

[0082] The dosage of sodium sulfide is 100-200 g / t, the dosage of pentyroxen is 50-75 g / t, and the dosage of butylammonium black powder is 35-45 g / t.

[0083] In the second selection, pentoflavonoids and butylated phthalate were added as collectors;

[0084] The dosage of pendimethalin is 40-55 g / t, and the dosage of butylammonium black powder is 25-35 g / t.

[0085] Optionally, for step e):

[0086] In the first sweep, pentoxamic acid and butylammonium black powder were added as collectors;

[0087] The dosage of pendimethalin is 100-120 g / t, and the dosage of butaniloxane is 100-120 g / t.

[0088] In the second sweep, pentoxamic acid and butylated phthalate were added as collectors;

[0089] The dosage of pendimethalin is 50-60 g / t, and the dosage of butaniloxane is 40-50 g / t.

[0090] In the third sweep, pentoflavonoids and butylated phthalate were added as collectors;

[0091] The dosage of pendimethalin is 30-50 g / t, and the dosage of butylammonium black powder is 20-30 g / t.

[0092] In this application, the reagent is divided into two equal parts and added in two separate steps during flotation to ensure that the reagent is fully dispersed in the slurry.

[0093] The flotation operation time in step e) is 6 minutes.

[0094] Optionally, the mixed slurry is further subjected to ultrasonic treatment before step e).

[0095] In this application, zinc kiln slag is a waste material generated during the zinc smelting process. It undergoes high-temperature smelting at 1100-1200℃. During this process, valuable metal ores are sintered and tightly embedded, and some are sintered with silicates to form a glassy substance. The incomplete dissociation of valuable metal ores during the early grinding process will result in some valuable metal ores not being recovered, leading to waste.

[0096] Furthermore, since there are tiny cracks in the ore particles during the early grinding process, ultrasonic treatment can further break up the ore particles in the mixed slurry, thereby enabling the valuable metal ore to be liberated in one step, improving the degree of liberation of the valuable metal ore, and facilitating the subsequent flotation of the metal ore.

[0097] Optionally, the ultrasonic treatment includes:

[0098] The mixed slurry is added to a mixing device and stirred at a speed of 100-120 rpm. At the same time, the mixed slurry is treated with ultrasonic waves at frequencies of 24 kHz, 36 kHz and 42 kHz for 0.5-1 h.

[0099] In this application, multiple frequencies of acoustic wave coupling are used to process the mixed slurry, which can effectively improve the liberation degree of valuable metal ores and facilitate subsequent flotation of the metal ores.

[0100] The stirring device includes a cylindrical body with an inverted conical bottom and a stirring paddle located at the center of the cylindrical body. The cylindrical wall is provided with multiple ultrasonic layers from top to bottom. Each ultrasonic layer includes an array of ultrasonic transducers that can emit ultrasonic waves of 24 kHz, 36 kHz and 42 kHz respectively. Specific Implementation

[0102] Example 1

[0103] A method for recovering valuable metals from zinc kiln slag includes the following steps:

[0104] S101. The zinc kiln slag is coarsely crushed into 3-5mm pieces and then dry ball-milled to obtain coarse material with a grinding fineness of ~0.074mm accounting for 35%.

[0105] S102. The coarse material is subjected to dry rod milling to obtain fine material with a grinding fineness of ~0.074mm accounting for 75%.

[0106] S103. Prepare a raw ore slurry with a concentration of 35% from the fine materials.

[0107] S104. Add diesel and No. 2 oil to the raw ore slurry, and use a flotation process of roughing and cleaning to pre-select carbon to obtain carbon concentrate and mixed ore.

[0108] During the roughing process, the amount of diesel added is 280g / t, and the amount of No. 2 oil used is 300g / t. Both diesel and No. 2 oil are added in two separate batches.

[0109] The carbon middlings obtained from the fine-refinement process are combined with the carbon roughing middlings obtained from the roughing process to obtain a mixed ore.

[0110] S105. The mixed ore is prepared into a mixed slurry with a concentration of 30%, and alkali is added to adjust the pH to 6.8. A flotation process of one roughing, two cleaning, and three scavenging followed by sequential return of the ore is adopted to obtain silver concentrate.

[0111] In the roughing process of S105, the dosage of copper sulfate is 800 g / t, sodium sulfide is 1500 g / t, pentyroflavin is 300 g / t, butylammonium black powder is 300 g / t, and No. 2 oil is 300 g / t. The above reagents are added in two batches.

[0112] In the first fine selection of S105, the dosage of sodium sulfide is 100g / t, the dosage of pentyroflavin is 50g / t, and the dosage of butylammonium black powder is 35g / t. The above agents are added in two batches.

[0113] In the second refinement of S105, the dosage of pendimethalin is 40g / t and the dosage of butylammonium black powder is 25g / t. The above agents are added in two separate batches.

[0114] In the first scan of S105, the dosage of pentyroflavin is 100g / t, and the dosage of butanol black powder is 100g / t. The above agents are added in two batches.

[0115] In the second scan of S105, the dosage of pendimethalin is 50 g / t, and the dosage of butylammonium black powder is 40 g / t. The above agents are added in two separate batches.

[0116] In the third scan of S105, the dosage of pentyroflavin is 30 g / t, and the dosage of butylammonium black powder is 20 g / t. The above agents are added in two separate batches.

[0117] Example 2

[0118] A method for recovering valuable metals from zinc kiln slag includes the following steps:

[0119] S201. The zinc kiln slag is coarsely crushed into 3-5mm pieces and then dry ball-milled to obtain coarse material with a grinding fineness of ~0.074mm accounting for 40%.

[0120] S202. The coarse material is subjected to dry rod milling to obtain fine material with a grinding fineness of ~0.074mm accounting for 80%.

[0121] S203. Prepare a raw ore slurry with a concentration of 40% from the fine materials.

[0122] S204. Add diesel and No. 2 oil to the raw ore slurry, and use a flotation process of roughing and cleaning to pre-select carbon to obtain carbon concentrate and mixed ore.

[0123] During the roughing process, the amount of diesel added is 320g / t, and the amount of No. 2 oil used is 400g / t. Both diesel and No. 2 oil are added in two separate batches.

[0124] The carbon middlings obtained from the fine-refinement process are combined with the carbon roughing middlings obtained from the roughing process to obtain a mixed ore.

[0125] S205. The mixed ore is prepared into a mixed slurry with a concentration of 35%, and alkali is added to adjust the pH to 7.5. A flotation process of one roughing, two cleaning, and three scavenging with sequential return of the ore is adopted to obtain silver concentrate.

[0126] In the roughing process of S205, the dosage of copper sulfate is 1200 g / t, sodium sulfide is 2500 g / t, pentyroflavin is 400 g / t, butylammonium black powder is 350 g / t, and No. 2 oil is 350 g / t. The above reagents are added in two batches.

[0127] In the first fine selection of S205, the dosage of sodium sulfide is 200g / t, the dosage of pentyroflavin is 75g / t, and the dosage of butylammonium black powder is 45g / t. The above agents are added in two batches.

[0128] In the second refinement of S205, the dosage of pendimethalin is 55g / t, and the dosage of butylammonium black powder is 35g / t. The above agents are added in two separate batches.

[0129] In the first scan of S205, the dosage of pentyroflavin is 120 g / t, and the dosage of butylammonium black powder is 120 g / t. The above agents are added in two batches.

[0130] In the second scan of S205, the dosage of pentyroflavin is 60 g / t, and the dosage of butylammonium black powder is 50 g / t. The above agents are added in two separate batches.

[0131] In the third scan of S205, the dosage of pentyroflavin is 50 g / t, and the dosage of butanol black powder is 30 g / t. The above agents are added in two separate batches.

[0132] Example 3

[0133] A method for recovering valuable metals from zinc kiln slag includes the following steps:

[0134] S301. The zinc kiln slag is coarsely crushed into 3-5mm pieces and then dry ball-milled to obtain coarse material with a grinding fineness of ~0.074mm accounting for 32%.

[0135] S302. The coarse material is subjected to dry rod milling to obtain fine material with a grinding fineness of ~0.074mm accounting for 77%.

[0136] S303. Prepare a raw ore slurry with a concentration of 38% from fine materials.

[0137] S304. Add diesel oil and No. 2 oil to the raw ore slurry, and use a flotation process of roughing and cleaning to pre-select carbon to obtain carbon concentrate and mixed ore.

[0138] During the roughing process, the amount of diesel added is 300g / t, and the amount of No. 2 oil used is 350g / t. Both diesel and No. 2 oil are added in two separate batches.

[0139] The carbon middlings obtained from the fine-refinement process are combined with the carbon roughing middlings obtained from the roughing process to obtain a mixed ore.

[0140] S305. The mixed ore is prepared into a mixed slurry with a concentration of 30-35%, and alkali is added to adjust the pH to 7.0. A flotation process of one roughing, two cleaning, and three scavenging followed by sequential return of the ore is adopted to obtain silver concentrate.

[0141] In the roughing process of S305, the dosage of copper sulfate is 1000 g / t, sodium sulfide is 2000 g / t, pentyroflavin is 350 g / t, butylammonium black powder is 330 g / t, and No. 2 oil is 325 g / t. The above reagents are added in two batches.

[0142] In the first fine selection of S305, the dosage of sodium sulfide is 150g / t, the dosage of pentyroflavin is 65g / t, and the dosage of butylammonium black powder is 40g / t. The above agents are added in two batches.

[0143] In the second refinement of S305, the dosage of pendimethalin is 50g / t and the dosage of butylammonium black powder is 30g / t. The above agents are added in two separate batches.

[0144] In the first scan of S305, the dosage of pentyroflavin is 110 g / t, and the dosage of butylammonium black powder is 110 g / t. The above agents are added in two batches.

[0145] In the second scan of S305, the dosage of pendimethalin is 55 g / t, and the dosage of butylammonium black powder is 45 g / t. The above agents are added in two separate batches.

[0146] In the third scan of S305, the dosage of pentyroflavin is 40 g / t and the dosage of butylammonium black powder is 25 g / t. The above agents are added in two separate batches.

[0147] Example 4

[0148] A method for recovering valuable metals from zinc kiln slag includes the following steps:

[0149] S401. The zinc kiln slag is coarsely crushed into 3-5mm pieces and then dry ball-milled to obtain coarse material with a grinding fineness of ~0.074mm accounting for 35%.

[0150] S402. The coarse material is subjected to dry rod milling to obtain fine material with a grinding fineness of ~0.074mm accounting for 80%.

[0151] S403. Prepare a raw ore slurry with a concentration of 35% from fine materials.

[0152] S404. Add diesel oil and No. 2 oil to the raw ore slurry, and use a flotation process of roughing and cleaning to pre-select carbon to obtain carbon concentrate and mixed ore.

[0153] During the roughing process, the amount of diesel added is 300g / t, and the amount of No. 2 oil used is 350g / t. Both diesel and No. 2 oil are added in two separate batches.

[0154] The carbon middlings obtained from the fine-refinement process are combined with the carbon roughing middlings obtained from the roughing process to obtain a mixed ore.

[0155] S405. The mixed ore is prepared into a mixed slurry with a concentration of 30-35%, and alkali is added to adjust the pH to 7.0. A flotation process of one roughing, two cleaning, and three scavenging followed by sequential return of the ore is adopted to obtain silver concentrate.

[0156] In the roughing process of S405, the dosage of copper sulfate is 1000 g / t, sodium sulfide is 2000 g / t, pentyroflavin is 350 g / t, butylammonium black powder is 350 g / t, and No. 2 oil is 300 g / t. The above reagents are added in two batches.

[0157] In the first fine selection of S405, the dosage of sodium sulfide is 150g / t, the dosage of pentyroflavin is 50g / t, and the dosage of butylammonium black powder is 40g / t. The above agents are added in two batches.

[0158] In the second refinement of S405, the dosage of pendimethalin is 40g / t and the dosage of butylammonium black powder is 30g / t. The above agents are added in two separate batches.

[0159] In the first scan of S405, the dosage of pentyroflavin is 100g / t, and the dosage of butylammonium black powder is 100g / t. The above agents are added in two batches.

[0160] In the second scan of S405, the dosage of pentyroflavin is 60 g / t and the dosage of butylammonium black powder is 40 g / t. The above agents are added in two separate batches.

[0161] In the third scan of S405, the dosage of pentyroflavin is 40 g / t, and the dosage of butylammonium black powder is 20 g / t. The above agents are added in two separate batches.

[0162] Example 5

[0163] A method for recovering valuable metals from zinc kiln slag includes the following steps:

[0164] S501 operates the same as S401.

[0165] S502, same operation as S402.

[0166] S503 operates the same as S403.

[0167] S504 operates the same as S404.

[0168] S505. Add the mixed slurry to the mixing device and stir at a speed of 120 rpm. At the same time, treat the mixed slurry with ultrasonic waves at frequencies of 24 kHz, 36 kHz and 42 kHz for 0.5 h.

[0169] S506. Alkali is added to the ultrasonically treated mixed slurry to adjust the pH to 7.0. A flotation process consisting of one roughing, two cleaning, and three scavenging operations with sequential return of the ore concentrate is adopted to obtain silver concentrate.

[0170] In the roughing process of S506, the dosage of copper sulfate is 1000 g / t, sodium sulfide is 2000 g / t, pentyroflavin is 350 g / t, butylammonium black powder is 350 g / t, and No. 2 oil is 300 g / t. The above reagents are added in two batches.

[0171] In the first fine selection of S506, the dosage of sodium sulfide is 150 g / t, the dosage of pentyroflavin is 50 g / t, and the dosage of butylammonium black powder is 40 g / t. The above agents are added in two batches.

[0172] In the second refinement of S506, the dosage of pendimethalin is 40g / t and the dosage of butanol black powder is 30g / t. The above agents are added in two separate batches.

[0173] In the first scan of S506, the dosage of pentyroflavin is 100g / t, and the dosage of butylammonium black powder is 100g / t. The above agents are added in two batches.

[0174] In the second scan of S506, the dosage of pentyroflavin is 60 g / t and the dosage of butylammonium black powder is 40 g / t. The above agents are added in two separate batches.

[0175] In the third scan of S506, the dosage of pentyroflavin is 40 g / t and the dosage of butylammonium black powder is 20 g / t. The above agents are added in two separate batches.

[0176] Example 6

[0177] A method for recovering valuable metals from zinc kiln slag includes the following steps:

[0178] S601 operates the same as S401.

[0179] S602, same operation as S402.

[0180] S603 operates the same as S403.

[0181] S604 operates the same as S404.

[0182] S605 and the rest of the operation are the same as S505, except that the ultrasonic treatment time is 1 hour.

[0183] S606 operates the same as S506.

[0184] Example 7

[0185] A method for recovering valuable metals from zinc kiln slag includes the following steps:

[0186] S701 operates the same as S401.

[0187] S702. Add the coarse material to a stirring device (ordinary stirring tank is acceptable) containing a 10% wt heavy oil petroleum ether solution, wherein the volume ratio of coarse material to passivating agent is 1:1 to 1:1.5, and stir at 100 rpm for 1 hour at 45 to 50°C.

[0188] After stirring, the mixture is filtered, and the filtered coarse material is vacuum dried at 50°C to recover the solvent and obtain the dried coarse material.

[0189] S703. Perform the same operation as S402 on the dried coarse material obtained in S702.

[0190] S704, same operation as S403.

[0191] S705 operates the same as S404.

[0192] S706 operates the same as S405.

[0193] Example 8

[0194] A method for recovering valuable metals from zinc kiln slag includes the following steps:

[0195] S801 operates the same as S401.

[0196] S802. Add the coarse material to a stirring device (ordinary stirring tank is acceptable) containing a heavy oil petroleum ether solution with a concentration of 10% wt, wherein the volume ratio of coarse material to passivating agent is 1:1 to 1:1.5, and stir at 50°C and 100 rpm for 1 hour.

[0197] After stirring, the mixture is filtered, and the filtered coarse material is vacuum dried at 50°C to recover the solvent and obtain the dried coarse material.

[0198] S803. Perform the same operation as S402 on the dried coarse material obtained in S802.

[0199] S804 operates the same as S403.

[0200] S805 operates the same as S404.

[0201] S806. Add the mixed slurry to the mixing device and stir at a speed of 120 rpm. At the same time, treat the mixed slurry with ultrasonic waves at frequencies of 24 kHz, 36 kHz and 42 kHz for 1 hour.

[0202] S806. Alkali is added to the ultrasonically treated mixed slurry to adjust the pH to 7.0. A flotation process consisting of one roughing, two cleaning, and three scavenging stages with sequential return of the ore concentrate is adopted to obtain silver concentrate.

[0203] In the roughing process of S806, the dosage of copper sulfate is 1000 g / t, sodium sulfide is 2000 g / t, pentyroflavin is 350 g / t, butylammonium black powder is 350 g / t, and No. 2 oil is 300 g / t. The above reagents are added in two batches.

[0204] In the first fine selection of S806, the dosage of sodium sulfide is 150g / t, the dosage of pentyroflavin is 50g / t, and the dosage of butylammonium black powder is 40g / t. The above agents are added in two batches.

[0205] In the second refinement of S806, the dosage of pendimethalin is 40g / t and the dosage of butylammonium black powder is 30g / t. The above agents are added in two separate batches.

[0206] In the first scan of S806, the dosage of pentyroflavin is 100g / t, and the dosage of butylammonium black powder is 100g / t. The above agents are added in two batches.

[0207] In the second scan of S806, the dosage of pentyroflavin is 60 g / t and the dosage of butylammonium black powder is 40 g / t. The above agents are added in two separate batches.

[0208] In the third scan of S806, the dosage of pentyroflavin is 40 g / t, and the dosage of butylammonium black powder is 20 g / t. The above agents are added in two separate batches.

[0209] Comparative Example 1

[0210] A method for recovering valuable metals from zinc kiln slag includes the following steps:

[0211] D101. The zinc kiln slag is coarsely crushed into 3-5mm pieces and then dry ball-milled to obtain fine material with a grinding fineness of ~0.074mm accounting for 80%.

[0212] D102, same operation as S403.

[0213] D103, same operation as S404.

[0214] D104. Add the mixed slurry to the mixing device and stir at a speed of 120 rpm. At the same time, treat the mixed slurry with ultrasonic waves at frequencies of 24 kHz, 36 kHz and 42 kHz for 1 hour.

[0215] D105. Alkali was added to the ultrasonically treated mixed slurry to adjust the pH to 7.0. A flotation process consisting of one roughing, two cleaning, and three scavenging fractions with sequential return of the ore was adopted to obtain silver concentrate.

[0216] In the roughing process of D105, the dosage of copper sulfate is 1000 g / t, sodium sulfide is 2000 g / t, pentyroflavin is 350 g / t, butylammonium black powder is 350 g / t, and No. 2 oil is 300 g / t. The above reagents are added in two batches.

[0217] In the first fine selection of D105, the dosage of sodium sulfide is 150 g / t, the dosage of pentyroflavin is 50 g / t, and the dosage of butylammonium black powder is 40 g / t. The above agents are added in two batches.

[0218] In the second refinement of D105, the dosage of pentyroflavin is 40 g / t, and the dosage of butylammonium black powder is 30 g / t. The above agents are added in two separate batches.

[0219] In the first scan of D105, the dosage of pentyroflavin is 100 g / t, and the dosage of butanol black powder is 100 g / t. The above agents are added in two batches.

[0220] In the second scan of D105, the dosage of pentyroflavin is 60 g / t, and the dosage of butylammonium black powder is 40 g / t. The above agents are added in two separate batches.

[0221] In the third scan of D105, the dosage of pentyroflavin is 40 g / t, and the dosage of butylammonium black powder is 20 g / t. The above agents are added in two separate batches.

[0222] Comparative Example 2

[0223] A method for recovering valuable metals from zinc kiln slag includes the following steps:

[0224] D201, same operation as S401.

[0225] D202. Add the coarse material to a stirring device (ordinary stirring tank is acceptable) containing a heavy oil petroleum ether solution with a concentration of 4% wt, wherein the volume ratio of coarse material to passivating agent is 1:1 to 1:1.5, and stir at 50°C and 100 rpm for 1 hour.

[0226] After stirring, the mixture is filtered, and the filtered coarse material is vacuum dried at 50°C to recover the solvent and obtain the dried coarse material.

[0227] D203. Perform the same operation as S402 on the dried coarse material obtained in D202.

[0228] D204, same operation as S403.

[0229] D205, same operation as S404.

[0230] D206, same operation as S405.

[0231] Comparative Example 3

[0232] A method for recovering valuable metals from zinc kiln slag includes the following steps:

[0233] D301 operates the same as S401.

[0234] D302. Add the coarse material to a stirring device (ordinary stirring tank is acceptable) containing a heavy oil petroleum ether solution with a concentration of 20% wt, wherein the volume ratio of coarse material to passivating agent is 1:1 to 1:1.5, and stir at 50°C and 100 rpm for 1 hour.

[0235] After stirring, the mixture is filtered, and the filtered coarse material is vacuum dried at 50°C to recover the solvent and obtain the dried coarse material.

[0236] D303. Perform the same operation as S402 on the dried coarse material obtained in D302.

[0237] D304, same operation as S403.

[0238] D305 operates the same as S404.

[0239] D306, same operation as S405.

[0240] Experimental Example

[0241] Zinc smelting kiln slag from a zinc smelter was selected as the raw ore. The mineral composition elements of the zinc kiln slag used as the experimental raw ore are shown in Table 1:

[0242] Table 1

[0243] content(%) 11.49 307.56 21.36 1.75 2.55 0.24 composition S <![CDATA[SiO2]]> <![CDATA[Al2O3]]> CaO MgO content(%) 4.65 22.06 9.17 6.71 1.87

[0244] The experimental raw ore was subjected to flotation using the methods described in Examples 1 to 8 and Comparative Examples 3 to recover carbon and valuable metals. The results are shown in Table 2.

[0245] Table 2:

[0246]

[0247]

[0248] Note: *Unit: g / t.

[0249] As can be seen from the data in Table 2 above, passivating the coarse material can significantly reduce the grade of valuable metals (copper and silver) in the carbon concentrate (Table 2, Examples 4, 7, and 8), thus lowering the content of valuable metals in the carbon concentrate. Ultrasonic treatment of the mixed slurry increases the grade of valuable metals in the silver concentrate (Table 2, Examples 4-6), indicating that ultrasonic treatment of the mixed slurry effectively improves the liberation degree of metals in the slurry, which is beneficial for the flotation of valuable metals. Furthermore, passivating the coarse material and ultrasonically treating the mixed slurry can significantly increase the content of valuable metals in the silver concentrate while reducing the grade of valuable metals in the carbon concentrate, and also reduce the mutual inclusion of carbon and valuable metals. This indicates that the practice of passivating the coarse material and ultrasonically treating the mixed slurry has a certain synergistic effect (Table 2, Examples 6-8). Moreover, the results of Examples 1 and 4 show that using a rod mill to grind the raw coarse material into fine material can improve the grade of valuable metals in the silver concentrate, indicating that the method of using a ball mill + rod mill has significant advantages over ball milling alone.

[0250] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for recovering valuable metals from zinc kiln slag, characterized in that, Includes the following steps: a) The zinc kiln slag is coarsely crushed into 3-5mm pieces and then dry ball-milled to obtain coarse material with a grinding fineness of -0.074mm accounting for 35-40%; b) The coarse material is subjected to dry rod milling to obtain fine material with a grinding fineness of -0.074 mm accounting for 75~80%; c) Prepare a raw ore slurry with a concentration of 35-40% from the fine materials; d) Add diesel and No. 2 oil to the raw ore slurry, and use a flotation process of roughing and cleaning to pre-select carbon to obtain carbon concentrate and mixed ore; e) The mixed ore is prepared into a mixed slurry with a concentration of 30-35%, alkali is added to adjust the pH to 6.8-7.5, and collectors, activators and frothers are added. A flotation process of one roughing, two cleaning and three scavenging with sequential return of the ore is adopted to obtain silver concentrate. After obtaining the rough material, a passivation process is performed, which includes: Add the coarse material to a stirring device containing a passivating agent, wherein the volume ratio of coarse material to passivating agent is 1:1 to 1:1.5, and stir at 45 to 50°C for 0.5 to 1.2 hours at a stirring speed of 100 to 120 rpm. After stirring, filter the material and then vacuum dry the filtered coarse material at 50°C to recover the solvent and obtain the dried coarse material. The passivating agent is a heavy oil petroleum ether solution with a concentration of 8-15%wt, prepared by dissolving heavy oil in petroleum ether. The mixed slurry is further subjected to ultrasonic treatment before flotation in step e), the ultrasonic treatment including: The mixed slurry is added to a stirring device and stirred at a speed of 100-120 rpm. At the same time, the mixed slurry is treated with ultrasonic waves at frequencies of 24 kHz, 36 kHz and 42 kHz for 0.5-1 h.

2. The method for recovering valuable metals from zinc kiln slag according to claim 1, characterized in that, For step d): During the roughing process, the amount of diesel added is 280~320g / t, and the amount of No. 2 oil used is 300~400g / t; The carbon middlings obtained from the fine-refinement process are combined with the carbon roughing middlings obtained from the roughing process to obtain a mixed ore.

3. The method for recovering valuable metals from zinc kiln slag according to claim 1, characterized in that, The collector is one or more of ethyl thiocyanate, butyl xanthate, pentosan xanthate, or butyl ammonium black powder.

4. The method for recovering valuable metals from zinc kiln slag according to claim 3, characterized in that, The foaming agent is one or more of No. 2 oil, eucalyptus oil, camphor oil, or methyl isobutyl methanol.

5. The method for recovering valuable metals from zinc kiln slag according to claim 4, characterized in that, The activator is one or more of copper sulfate, sodium sulfide, sodium hydrosulfide, and ethylenediamine phosphate; The alkali is one or more of sodium carbonate, calcium hydroxide, potassium carbonate, sodium bicarbonate, and ammonia water.

6. The method for recovering valuable metals from zinc kiln slag according to any one of claims 1 to 5, characterized in that, For step e): In the roughing process, copper sulfate and sodium sulfide are added as activators, pentoxamic acid and butylammonium black powder are added as collectors, and No. 2 oil is added as a foaming agent. The dosage of copper sulfate is 800~1200g / t, the dosage of sodium sulfide is 1500~2500g / t, the dosage of pentyroflavin is 300~400g / t, the dosage of butylammonium black powder is 300~350g / t, and the dosage of No. 2 oil is 300~350g / t.

7. The method for recovering valuable metals from zinc kiln slag according to any one of claims 1 to 5, characterized in that, For step e): In the first selection process, sodium sulfide was added as an activator, and pentoxanone and butylammonium black powder were added as collectors. The dosage of sodium sulfide is 100~200g / t, the dosage of pentyroxen is 50~75 g / t, and the dosage of butylammonium black powder is 35~45 g / t. In the second selection, pentoflavonoids and butylated phthalate were added as collectors; The dosage of pendimethalin is 40-55 g / t, and the dosage of butylammonium black powder is 25-35 g / t.

8. The method for recovering valuable metals from zinc kiln slag according to any one of claims 1 to 5, characterized in that, For step e): In the first sweep, pentoxamic acid and butylammonium black powder were added as collectors; The dosage of pendimethalin is 100~120 g / t, and the dosage of butaniloxane is 100~120 g / t; In the second sweep, pentoxamic acid and butylated phthalate were added as collectors; The dosage of pendimethalin is 50-60 g / t, and the dosage of butaniloxane is 40-50 g / t. In the third sweep, pentoflavonoids and butylated phthalate were added as collectors; The dosage of pendimethalin is 30-50 g / t, and the dosage of butylammonium black powder is 20-30 g / t.

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