Low-carbonization treatment method for recovering valuable metals from wet zinc smelting slag

Abstract

This invention discloses a low-carbonization treatment method for recovering valuable metals from hydrometallurgical zinc slag. First, polyvinyl alcohol is added to fresh, hot slag slurry. After the slurry cools naturally, lime is added to adjust the pH to 6-8. Then, sodium silicate, a gangue inhibitor, and a collector are added for three roughing, two cleaning, and two scavenging processes. The tailings are collected and pre-classified, ground, classified, and regrinded until the fineness of the hydrocyclone overflow slurry is less than 0.023 mm and the ore content is 65.25-73.28% by mass. The hydrocyclone overflow slurries collected from each stage are mixed evenly and used as flotation feed. Suitable activators, flocculants, and collectors are added for flocculation flotation to recover valuable metals. The byproduct calcium sulfate produced by this method can be sold, improving economic efficiency. This invention achieves low-carbonization treatment and resource utilization of hydrometallurgical zinc slag and has strong industrial application value.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, specifically a method for low-carbonization treatment of zinc slag before recovering valuable metals. Background Technology

[0002] Every year, my country generates a large amount of hydrometallurgical zinc slag due to smelting processes. This slag contains various metallic elements such as copper, lead, and zinc, as well as valuable rare metals like silver, gold, cadmium, and indium. In recent years, the low-carbon treatment of smelting waste slag and the secondary utilization of waste resources have become our research focus. Currently, there are many methods for treating hydrometallurgical zinc slag both domestically and internationally, mainly including flotation, pyrometallurgical processes, hydrometallurgical processes, combined pyrometallurgical and hydrometallurgical processes, and combined beneficiation and smelting methods. Among these, the combined beneficiation and smelting method has achieved relatively good results. Although the combined beneficiation and smelting method has made some progress in small-scale experimental research, it has not yet been widely promoted and applied industrially. The reasons are as follows: First, the valuable metals in the wet zinc smelting slag are in the form of inclusions, which require the addition of a large amount of concentrated sulfuric acid to break down the inclusions and release the valuable elements; second, the wet zinc smelting slag itself is highly acidic, which severely corrodes the equipment during the beneficiation process, requiring regular equipment maintenance and replacement, which is costly; third, under highly acidic conditions, the addition of activators and collectors can easily produce toxic and harmful gases, which are very harmful to the health of operators. Summary of the Invention

[0003] The purpose of this invention is to provide a low-carbonization treatment method for recovering valuable metals from wet zinc smelting slag, so as to solve the problems existing in the prior art.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for low-carbonization treatment of zinc slag before recovering valuable metals from it in a hydrometallurgical process includes the following steps:

[0006] Step 1, Stirring: Take the hot slag slurry produced by wet zinc smelting and mix it with polyvinyl alcohol at a mass ratio of 3-2:1 until uniform. The temperature of the hot slag slurry is 60-80℃.

[0007] Step 2, Neutralization reaction: After the slurry mixed in Step 1 has cooled to room temperature naturally, add lime to adjust the pH of the slurry to 6-8;

[0008] Step 3, reverse flotation: Add 4500-5500g / t of sodium silicate inhibitor and 200-400g / t of collector DY to the slurry from Step 2, and perform three roughing, two cleaning, and two scavenging processes to obtain calcium sulfate concentrate and calcium sulfate tailings.

[0009] Step 4, Classification-Grinding-Classification-Regrinding: The calcium sulfate tailings obtained in Step 3 are added to a hydrocyclone for pre-classification to obtain primary hydrocyclone overflow slurry and primary undercooked sand. The primary undercooked sand is ground and then fed back into the hydrocyclone for grinding and classification to obtain secondary hydrocyclone overflow slurry and secondary undercooked sand. The secondary undercooked sand is returned to the ball mill for further grinding until the fineness of the hydrocyclone overflow slurry is less than 0.023 mm and the slag content is 65.25%-73.28% by mass. The hydrocyclone overflow slurry collected from several times is mixed evenly and used as flotation feed. Appropriate activators, flocculants, and collectors are added for flocculation flotation to recover valuable metals.

[0010] Preferably, the hot slag slurry produced by the wet zinc smelting process is lead-silver slag.

[0011] Preferably, the collector DY in step 3 is an emulsified synthesized collector, the main components of which are sodium dodecylbenzenesulfonate and N-alkylaminobutyric acid.

[0012] Preferably, the steps of three roughing, two cleaning, and two scavenging in step 3 are as follows: First roughing is performed by adding 2000-2500 g / t of sodium silicate and 100-180 g / t of collector DY to obtain rough concentrate 1 and tailings 1; a second roughing is performed by adding 2000-2500 g / t of sodium silicate and 100-180 g / t of collector DY to tailings 1 to obtain rough concentrate 2 and tailings 2; a third roughing is performed by adding 500 g / t of sodium silicate to tailings 2 to obtain rough concentrate 3 and tailings 3; two blank cleanings are performed on concentrate 1 + rough concentrate 2 + rough concentrate 3 to obtain the final calcium sulfate product and middlings 1 and 2; 0-40 g / t of collector DY is added to tailings 3 for two scavenging operations to produce the final tailings and middlings 3 and 4, with all middlings returned sequentially to the previous operation.

[0013] The low-carbonization treatment process for wet zinc smelting slag described in this invention consists of: stirring, neutralization reaction, and reverse flotation. In step 1, adding polyvinyl alcohol can break down inclusions in the slag slurry and release valuable elements. In step 2, adding lime neutralizes the slag slurry, reduces its acidity, prepares it for subsequent flotation, reduces equipment corrosion, lowers costs, and prevents the generation of toxic and harmful gases when adding activators and collectors during flotation under acidic conditions, thus protecting human health. Since the addition of lime depletes the valuable metal grade in the slag slurry, the reverse flotation in step 3 aims to enrich the valuable metals and produces calcium sulfate as a byproduct that can be sold, thereby improving economic efficiency.

[0014] Sodium silicate is added in step 3 because it has strong water absorption and can be tightly adsorbed on the surface of gangue minerals, especially silicate minerals, making the gangue minerals more hydrophilic and thus inhibiting their growth. Meanwhile, collector DY is an organic compound with strong selective collection ability, which can effectively collect calcium sulfate, ensuring both the recovery rate and quality of calcium sulfate.

[0015] Step 4 of this invention employs a pre-classification-grinding-classification-regrinding approach. Since the reverse flotation tailings are inherently fine, pre-classification separates a portion of the qualified particles, preventing over-grinding. After grinding, classification and regrinding of the sediment are carried out to ensure fineness and reduce grinding costs. Following this process, valuable metals in hydrometallurgical zinc slag can be easily recovered using flocculation flotation, solving the problem that hydrometallurgical zinc slag cannot be industrially applied.

[0016] This invention realizes the low-carbon treatment and resource utilization of wet zinc smelting slag, and has strong industrial application value. Attached Figure Description

[0017] Figure 1 This is a flowchart of the method described in this invention. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings.

[0019] Example 1

[0020] like Figure 1 The method shown includes the following steps for the low-carbonization treatment of zinc slag before recovering valuable metals:

[0021] Step 1, Stirring: Take the hot lead-silver slag slurry with a temperature of 70℃ produced by wet zinc smelting and mix it with polyvinyl alcohol at a mass ratio of 3:1. The gold content in the hot slag slurry is 0.93g / t and the silver content is 225.87g / t.

[0022] Step 2, Neutralization reaction: After the slurry mixed in Step 1 has cooled to room temperature naturally, add lime to adjust the pH of the slurry to 7.5;

[0023] Step 3, Reverse Flotation: In the first roughing stage, 2000 g / t of sodium silicate inhibitor and 120 g / t of collector DY are added to the slurry from Step 2 to obtain rough concentrate 1 and tailings 1. In the second roughing stage, 2000 g / t of sodium silicate and 120 g / t of collector DY are added to tailings 1 to obtain rough concentrate 2 and tailings 2. In the third roughing stage, 500 g / t of sodium silicate is added to tailings 2 to obtain rough concentrate 3 and tailings 3. The mixture of concentrate 1, rough concentrate 2, and rough concentrate 3 is subjected to two blank cleaning processes to obtain the final calcium sulfate product and middlings 1 and 2. The tailings 3 is subjected to two blank scavenging processes to produce the final calcium sulfate tailings and middlings 3 and 4. All middlings are returned to the previous operation in sequence.

[0024] Step 4, Classification-Grinding-Classification-Regrinding: The calcium sulfate tailings obtained in Step 3 are added to a hydrocyclone for pre-classification to obtain primary hydrocyclone overflow slurry and primary undercooked sand. The primary undercooked sand is ground and then fed back into the hydrocyclone for further grinding and classification to obtain secondary hydrocyclone overflow slurry and secondary undercooked sand. The secondary undercooked sand is returned to the ball mill for further grinding until the fineness of the hydrocyclone overflow slurry is less than 0.023 mm and the slag content is 68.5% by mass. The hydrocyclone overflow slurry collected from several times is mixed evenly and used as flotation feed. Appropriate activators, flocculants, and collectors are added for flocculation flotation to obtain a silver concentrate grade of 2678.95 g / t with a recovery rate of 84.44%, and a gold grade of 10.37 g / t with a recovery rate of 90.12%.

[0025] Example 2

[0026] like Figure 1 The method shown includes the following steps for the low-carbonization treatment of zinc slag before recovering valuable metals:

[0027] Step 1, Stirring: Take the hot lead-silver slag slurry with a temperature of 80℃ produced by wet zinc smelting and mix it with polyvinyl alcohol at a mass ratio of 2:1. The gold content in the hot slag slurry is 1.23g / t and the silver content is 289.32g / t.

[0028] Step 2, Neutralization reaction: After the slurry mixed in Step 1 has cooled to room temperature naturally, add lime to adjust the pH of the slurry to 8;

[0029] Step 3, Reverse Flotation: In the first roughing stage, 2500 g / t of sodium silicate inhibitor and 180 g / t of collector DY are added to the slurry from Step 2 to obtain rough concentrate 1 and tailings 1. In the second roughing stage, 2500 g / t of sodium silicate and 150 g / t of collector DY are added to tailings 1 to obtain rough concentrate 2 and tailings 2. In the third roughing stage, 500 g / t of sodium silicate is added to tailings 2 to obtain rough concentrate 3 and tailings 3. The mixture of concentrate 1, rough concentrate 2, and rough concentrate 3 undergoes two blank cleaning processes to obtain the final calcium sulfate product and middlings 1 and 2. In the second scavenging stage, 20 g / t of collector DY is added to tailings 3 to produce the final calcium sulfate tailings and middlings 3 and 4. All middlings are returned to the previous operation in sequence.

[0030] Step 4, Classification-Grinding-Classification-Regrinding: The calcium sulfate tailings obtained in Step 3 are added to a hydrocyclone for pre-classification to obtain primary hydrocyclone overflow slurry and primary undercooked sand. The primary undercooked sand is ground and then fed back into the hydrocyclone for further grinding and classification to obtain secondary hydrocyclone overflow slurry and secondary undercooked sand. The secondary undercooked sand is returned to the ball mill for further grinding until the fineness of the hydrocyclone overflow slurry is less than 0.023 mm and the slag content is 72.67% by mass. The hydrocyclone overflow slurry collected from several stages is mixed evenly and used as flotation feed. Appropriate activators, flocculants, and collectors are added for flocculation flotation, resulting in a silver concentrate grade of 3325.61 g / t with a recovery rate of 83.67% and a gold grade of 11.38 g / t with a recovery rate of 91.76%.

[0031] Example 3

[0032] like Figure 1 The method shown includes the following steps for the low-carbonization treatment of zinc slag before recovering valuable metals:

[0033] Step 1, Stirring: Take the hot lead-silver slag slurry with a temperature of 65℃ produced by wet zinc smelting and mix it with polyvinyl alcohol at a mass ratio of 2.5:1. The gold content in the hot slag slurry is 1.12g / t and the silver content is 258.94g / t.

[0034] Step 2, Neutralization reaction: After the slurry mixed in Step 1 has cooled to room temperature naturally, add lime to adjust the pH of the slurry to 6.5;

[0035] Step 3, Reverse Flotation: In the first roughing stage, 2500 g / t of sodium silicate inhibitor and 180 g / t of collector DY are added to the slurry from Step 2 to obtain rough concentrate 1 and tailings 1. In the second roughing stage, 2200 g / t of sodium silicate and 180 g / t of collector DY are added to tailings 1 to obtain rough concentrate 2 and tailings 2. In the third roughing stage, 500 g / t of sodium silicate is added to tailings 2 to obtain rough concentrate 3 and tailings 3. The mixture of concentrate 1, rough concentrate 2, and rough concentrate 3 undergoes two blank cleaning processes to obtain the final calcium sulfate product and middlings 1 and 2. In the second scavenging stage, 20 g / t of collector DY is added to tailings 3 to produce the final calcium sulfate tailings and middlings 3 and 4. All middlings are returned to the previous operation in sequence.

[0036] Step 4, Classification-Grinding-Classification-Regrinding: The calcium sulfate tailings obtained in Step 3 are added to a hydrocyclone for pre-classification to obtain primary hydrocyclone overflow slurry and primary undercooked sand. The primary undercooked sand is ground and then fed back into the hydrocyclone for further grinding and classification to obtain secondary hydrocyclone overflow slurry and secondary undercooked sand. The secondary undercooked sand is returned to the ball mill for further grinding until the fineness of the hydrocyclone overflow slurry is less than 0.023 mm and the slag content is 69.85% by mass. The hydrocyclone overflow slurry collected from several times is mixed evenly and used as flotation feed. Appropriate activators, flocculants, and collectors are added for flocculation flotation to obtain a silver concentrate grade of 2987.63 g / t with a recovery rate of 84.32% and a gold grade of 12.17 g / t with a recovery rate of 90.58%.

[0037] Example 4

[0038] like Figure 1 The method shown includes the following steps for the low-carbonization treatment of zinc slag before recovering valuable metals:

[0039] Step 1, Stirring: Take the hot lead-silver slag slurry produced by wet zinc smelting at a temperature of 60℃ and mix it with polyvinyl alcohol at a mass ratio of 2.8:1. The gold content in the hot slag slurry is 0.93g / t and the silver content is 225.87g / t.

[0040] Step 2, Neutralization reaction: After the slurry mixed in Step 1 has cooled to room temperature naturally, add lime to adjust the pH of the slurry to 6;

[0041] Step 3, Reverse Flotation: In the first roughing stage, 2500 g / t of sodium silicate inhibitor and 180 g / t of collector DY are added to the slurry from Step 2 to obtain rough concentrate 1 and tailings 1. In the second roughing stage, 1700 g / t of sodium silicate and 180 g / t of collector DY are added to tailings 1 to obtain rough concentrate 2 and tailings 2. In the third roughing stage, 500 g / t of sodium silicate is added to tailings 2 to obtain rough concentrate 3 and tailings 3. The mixture of concentrate 1, rough concentrate 2, and rough concentrate 3 undergoes two blank cleaning processes to obtain the final calcium sulfate product and middlings 1 and 2. In the second scavenging stage, 40 g / t of collector DY is added to tailings 3 to produce the final calcium sulfate tailings and middlings 3 and 4. All middlings are returned to the previous operation in sequence.

[0042] Step 4, Classification-Grinding-Classification-Regrinding: The calcium sulfate tailings obtained in Step 3 are added to a hydrocyclone for pre-classification to obtain primary hydrocyclone overflow slurry and primary undercooked sand. The primary undercooked sand is ground and then fed back into the hydrocyclone for further grinding and classification to obtain secondary hydrocyclone overflow slurry and secondary undercooked sand. The secondary undercooked sand is returned to the ball mill for further grinding until the fineness of the hydrocyclone overflow slurry is less than 0.023 mm and the slag content is 73.28% by mass. The hydrocyclone overflow slurry collected from several stages is mixed evenly and used as flotation feed. Appropriate activators, flocculants, and collectors are added for flocculation flotation, yielding a silver concentrate grade of 2736.52 g / t with a recovery rate of 81.33%, and a gold grade of 10.62 g / t with a recovery rate of 87.45%.

[0043] Example 5

[0044] like Figure 1 The method shown includes the following steps for the low-carbonization treatment of zinc slag before recovering valuable metals:

[0045] Step 1, Stirring: Take the hot lead-silver slag slurry with a temperature of 75℃ produced by wet zinc smelting and mix it with polyvinyl alcohol at a mass ratio of 2.6:1. The gold content in the hot slag slurry is 1.07g / t and the silver content is 254.43g / t.

[0046] Step 2, Neutralization reaction: After the slurry mixed in Step 1 has cooled to room temperature naturally, add lime to adjust the pH of the slurry to 7;

[0047] Step 3, Reverse Flotation: In the first roughing stage, 2500 g / t of sodium silicate inhibitor and 100 g / t of collector DY are added to the slurry from Step 2 to obtain rough concentrate 1 and tailings 1. In the second roughing stage, 2000 g / t of sodium silicate and 100 g / t of collector DY are added to tailings 1 to obtain rough concentrate 2 and tailings 2. In the third roughing stage, 500 g / t of sodium silicate is added to tailings 2 to obtain rough concentrate 3 and tailings 3. The mixture of concentrate 1, rough concentrate 2, and rough concentrate 3 is subjected to two blank cleaning processes to obtain the final calcium sulfate product and middlings 1 and 2. The tailings 3 is subjected to two blank scavenging processes to produce the final calcium sulfate tailings and middlings 3 and 4. All middlings are returned to the previous operation in sequence.

[0048] Step 4, Classification-Grinding-Classification-Regrinding: The calcium sulfate tailings obtained in Step 3 are added to a hydrocyclone for pre-classification to obtain primary hydrocyclone overflow slurry and primary undercooked sand. The primary undercooked sand is ground and then fed back into the hydrocyclone for further grinding and classification to obtain secondary hydrocyclone overflow slurry and secondary undercooked sand. The secondary undercooked sand is returned to the ball mill for further grinding until the fineness of the hydrocyclone overflow slurry is less than 0.023 mm and the slag content is 65.25% by mass. The hydrocyclone overflow slurry collected from several times is mixed evenly and used as flotation feed. Appropriate activators, flocculants, and collectors are added for flocculation flotation to obtain a silver concentrate grade of 3126.34 g / t with a recovery rate of 81.56% and a gold grade of 11.17 g / t with a recovery rate of 90.45%.

[0049] In the above embodiments, the collector DY in step 3 is an emulsion-synthesized collector, the main components of which are preferably sodium dodecylbenzenesulfonate and N-alkylaminobutyric acid.

[0050] This invention realizes the low-carbon treatment and resource utilization of wet zinc smelting slag, and has strong industrial application value.

[0051] The above are merely preferred embodiments of the present invention. It should be noted that, for those skilled in the art, other equivalent modifications and improvements can be made based on the technical teachings provided by the present invention, and these should also be considered within the scope of protection of the present invention.

Claims

1. A method for low-carbonization treatment of zinc slag before recovering valuable metals, characterized in that: Includes the following steps: Step 1, Stirring: Take the hot slag slurry produced by wet zinc smelting and mix it with polyvinyl alcohol at a mass ratio of 3-2:1 until uniform. The temperature of the hot slag slurry is 60-80℃. Step 2, Neutralization reaction: After the slurry mixed in Step 1 has cooled to room temperature naturally, add lime to adjust the pH of the slurry to 6-8; Step 3, reverse flotation: Add 4500-5500 g / t of sodium silicate inhibitor and 200-400 g / t of collector DY to the slurry from Step 2, and perform three roughing, two cleaning, and two scavenging processes to obtain calcium sulfate concentrate and calcium sulfate tailings; collector DY is an emulsified synthetic collector composed of sodium dodecylbenzenesulfonate and N-alkylaminobutyric acid; Step 4, Classification-Grinding-Classification-Regrinding: The calcium sulfate tailings obtained in Step 3 are added to a hydrocyclone for pre-classification to obtain primary hydrocyclone overflow slurry and primary undercooked sand. The primary undercooked sand is ground and then fed back into the hydrocyclone for grinding and classification to obtain secondary hydrocyclone overflow slurry and secondary undercooked sand. The secondary undercooked sand is returned to the ball mill for further grinding until the fineness of the hydrocyclone overflow slurry is less than 0.023 mm and the slag content is 65.25%-73.28% by mass. The hydrocyclone overflow slurry collected from several times is mixed evenly and used as flotation feed. Appropriate activators, flocculants, and collectors are added for flocculation flotation to recover valuable metals.

2. The method for low-carbonization treatment of valuable metals before recovering zinc slag in hydrometallurgical processes according to claim 1, characterized in that: The hot slag slurry produced by the wet zinc smelting process is lead-silver slag.

3. The method for low-carbonization treatment of valuable metals before recovering from wet zinc smelting slag, as described in claim 1 or 2, is characterized in that: The steps in step 3, namely three roughing, two cleaning, and two scavenging processes, are as follows: First roughing is performed by adding 2000-2500 g / t of sodium silicate and 100-180 g / t of collector DY, yielding rough concentrate 1 and tailings 1; a second roughing is performed by adding 2000-2500 g / t of sodium silicate and 100-180 g / t of collector DY to tailings 1, yielding rough concentrate 2 and tailings 2; a third roughing is performed by adding 500 g / t of sodium silicate to tailings 2, yielding rough concentrate 3 and tailings 3; two blank cleaning processes are performed on concentrate 1 + rough concentrate 2 + rough concentrate 3 to obtain the final calcium sulfate product and middlings 1 and 2; 0-40 g / t of collector DY is added to tailings 3 for two scavenging processes, producing the final tailings and middlings 3 and 4, with all middlings returned sequentially to the previous operation.

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