A method for the comprehensive recovery of valuable metals from zinc leaching hazardous waste residue

Abstract

A method for the comprehensive recovery of valuable metals from zinc leaching hazardous waste residue, relating to the field of smelting solid waste treatment technology, specifically includes the following steps: After leaching residue is filtered by pressure, it undergoes grinding, during which a composite inhibitor is added. Qualified particle sizes are activated by ultrasound and then fed into flotation. A composite collector is used in a "two-roughing, three-cleansing, two-scavenging" flotation process to obtain crude silver concentrate. The crude silver concentrate is then activated by microwave and sent to oxidative roasting-acid leaching to obtain rich silver concentrate. The flotation tailings are microwave-activated and then sent to a rotary kiln for roasting. A bag filter recovers valuable metals such as zinc and indium from the flue gas. The roasting flue gas is desulfurized and discharged in compliance with standards. The use of ultrasound and microwave pretreatment results in high valuable metal recovery rates, a simple process flow, environmental friendliness, and broad application prospects, realizing the resource utilization of zinc leaching hazardous waste residue.

Description

Technical Field

[0001] This invention relates to the field of leaching solid waste treatment technology, specifically a method for the comprehensive recovery of valuable metals from zinc leaching hazardous waste residue. Background Technology

[0002] Existing zinc leaching hazardous waste residues contain complex and diverse compositions, making treatment challenging. The main processes for extracting valuable metals from these residues include hydrometallurgical leaching, pyrometallurgical smelting, flotation, and combined processes. Hydrometallurgical leaching places high demands on equipment, which is susceptible to corrosion, and generates large amounts of wastewater that are difficult to recycle. Pyrometallurgical processes result in rapid volatilization of valuable metals such as zinc, indium, and iron, leading to high recovery rates, fast reaction speeds, and simple phase separation. However, they are less effective at recovering hazardous waste residues containing precious metals such as silver and gold, resulting in lower recovery rates. Flotation can be used to recover silver from leaching residues at a lower cost. However, due to the complex composition of the leaching residue, silver often exists in inclusions, making it difficult for ordinary flotation collectors to adsorb onto the target mineral surface, thus resulting in low silver recovery rates. Furthermore, the high acidity and temperature of the leaching residue pulp make it difficult for flotation collectors such as butyl xanthate and ethyl thiocyanate to adapt to the pulp system when used alone, resulting in poor collection performance. Therefore, it is difficult to obtain satisfactory production indicators by directly flotation or pyrometallurgical processing of zinc leaching residue. Thus, finding a method to efficiently recover valuable metals from zinc leaching hazardous waste residue is of great significance. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for the comprehensive recovery of valuable metals from zinc leaching waste residue, thereby solving problems such as low recovery rate of valuable metals from zinc leaching waste residue, high requirements for disposal technology, high cost, and environmental pollution.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a method for comprehensively recovering valuable metals from zinc leaching hazardous waste residue, wherein the main chemical components and mass percentages of the raw material zinc leaching hazardous waste residue are: Zn 8.62%–11.39%, In 0.056%–0.10%, Fe 17.60%–24.11%, CaO 4.62%–8.96%, SiO2 4.24%–6.00%, and silver content 70.36 g / t–230.11 g / t, comprising the following steps:

[0005] (1) After the zinc leaching hazardous waste residue is filtered, it is sent to the grinding operation. During the grinding process, a mixed inhibitor composed of 3-4 parts by weight of calcium oxide and 0.5-1 parts by weight of sodium hexametaphosphate is added.

[0006] (2) The qualified grinding particles are sent to flotation after ultrasonic activation treatment. The ultrasonic frequency is 30KHz and the ultrasonic treatment time is 3min.

[0007] (3) A rough silver concentrate is obtained by adopting the "two roughing, three cleaning and two scavenging" flotation process. A composite collector is added during the flotation process, which is a compound of sodium dimethyl dithiocarbamate (4-6 parts) and butyl ammonium black powder (1-3 parts). The dosage range of the composite collector in the flotation process is 50g / t to 800g / t, the dosage range of sodium sulfide is 250g / t to 480g / t, and the dosage range of pine oil is 15g / t to 75.0g / t.

[0008] (4) After the flotation tailings are filtered, they are mixed in a ratio of tailings: anthracite: coke = 1: 0.20-0.30: 0.1-0.15, and then sent to a rotary kiln for roasting after microwave activation treatment. The microwave frequency is 4 GHz, the treatment time is 5-10 min, the roasting temperature is 1020℃-1100℃, and the roasting time is 0.5-1 h.

[0009] (5) The roasting flue dust is recovered by a bag filter, and zinc and indium in the flue dust are recovered and the flue gas is discharged.

[0010] In step (1), the grinding media is steel balls, and the grinding concentration is 50% to 60%.

[0011] In step (3), the proportion of -0.074mm particles is 75% to 88%.

[0012] The outlet flue gas temperature in step (4) is 620℃~750℃.

[0013] The main chemical components and mass percentages of the kiln slag in step (5) are: Zn 0.19%~0.25%, In 0.014%~0.018%, Fe 20.08%~28.25%, and CaO 8.63%~13.65%.

[0014] The beneficial effects of this invention are as follows:

[0015] 1. A composite inhibitor was added during the grinding stage to reduce the coverage of CaO and SiO2 on the silver surface. Ultrasonic activation treatment was then used to expose the fresh surface of the silver, which greatly improved the adsorption efficiency of the subsequent collector.

[0016] 2. The collector, a combination of sodium dimethyl dithiocarbamate and butylammonium black powder, can form complexes with the surface of fresh silver through -SCS- and -SPS- groups, exhibiting stronger collecting performance compared to single flotation collector systems. It is highly adaptable to leaching residue slurry systems, boasts high recovery rates, and is environmentally friendly.

[0017] 3. When raw materials are directly fed into a rotary kiln for roasting, they tend to stick together and clump, resulting in uneven heating and slow metal volatilization. After microwave treatment, the selective absorption characteristics of the materials create numerous cracks on the absorbing surface due to the thermal effect. This allows for synergistic oxidative roasting with anthracite and coke, resulting in more thorough roasting, more uniform furnace temperature, and rapid volatilization of zinc and indium into the flue gas as metal oxides. This significantly improves roasting efficiency and reduces enterprise costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the process flow of the method of the present invention.

[0019] Figure 2 This is a schematic diagram of the flotation process in this invention. Detailed Implementation

[0020] Example 1

[0021] This embodiment is an example of a method for comprehensively recovering valuable metals from zinc leaching hazardous waste residue according to the present invention. The lead-zinc smelting hazardous waste residue used in this embodiment is leaching hazardous waste residue stockpiled in a certain location in Guangxi. The main chemical components and mass percentages of the hazardous waste residue are: Zn 8.62%, In 0.056%, Fe 17.97%, CaO 8.13%, SiO2 6.00%. The waste residue contains 70.36 g / t of silver. The method includes the following steps:

[0022] (1) 10 kg of leaching residue is filtered and then fed into the grinding operation. The grinding concentration is 50%. During the grinding process, a mixed inhibitor is added. The mixed inhibitor is composed of 3 parts calcium oxide and 0.5 parts sodium hexametaphosphate. After the slurry is adjusted and stirred, it is sent to the flotation.

[0023] (2) The qualified grinding particles are sent to flotation after ultrasonic activation treatment. The proportion of -0.074mm particles is 82%. The ultrasonic treatment time is 3min and the frequency is 30KHz.

[0024] (3) A "two-roughing, three-cleansing, two-scavenging" flotation process is adopted. The tailings from the first roughing stage enter the second roughing stage. The froth from the first and second roughing stages is cleaned three times to produce crude silver concentrate. The tailings after the second roughing stage enter the scavenging stage and are scavenged twice to produce flotation tailings. The -0.074mm particle size accounts for 82%, and is prepared by compounding sodium dimethyl dithiocarbamate 4 and butyl ammonium black powder 1 part. The dosage range of the mixed collector during the flotation process is 50g / t to 750g / t, the dosage range of sodium sulfide is 250g / t to 400g / t, and the dosage range of pine oil is 15g / t to 60g / t.

[0025] (4) The flotation tailings are microwave activated and then sent to a rotary kiln for roasting. The tailings are mixed and roasted in a weight ratio of 1:0.20:0.10. The microwave frequency is 4GHz and the processing time is 5min.

[0026] (5) Dust is removed from the roasting flue gas using a bag filter, and valuable metals zinc and indium are recovered from the flue gas. The roasting flue gas is treated to meet the national standard GB 25466-2010 for emission, and the kiln slag meets the national standard GB / T37785-2019 for sale.

[0027] In this embodiment, after the above steps, the crude silver concentrate contains 1880.30 g / t of silver, with a recovery rate of 84.46%; the main chemical components of the smelting dust are: Zn 852 g, In 5.4 g, zinc recovery rate 98.83%, and indium recovery rate 96.42%; the kiln slag contains: Zn 0.25%, In 0.017%, Fe 25.72%, CaO 13.65%, and SiO2 12.94%.

[0028] Example 2

[0029] This embodiment is another example of the method for comprehensively recovering valuable metals from zinc leaching hazardous waste residue according to the present invention. The tin-zinc smelting hazardous waste residue used in this embodiment is leaching hazardous waste residue stockpiled in a certain area of ​​Guangxi. The main chemical components and mass percentages of the hazardous waste residue are: Zn 10.10%, In 0.10%, Fe 17.60%, CaO 8.80%, SiO2 4.74%, and silver content 111.83 g / t. The recovery process of this method includes the following steps:

[0030] (1) 10 kg of leaching residue was filtered and then fed into the grinding operation. The grinding concentration was 50%. During the grinding process, a mixed inhibitor was added. The mixed inhibitor was composed of 3 parts calcium oxide and 0.5 parts sodium hexametaphosphate.

[0031] (2) The qualified grinding particles are sent to flotation after ultrasonic activation treatment. The ultrasonic treatment time is 3 minutes and the frequency is 30KHz.

[0032] (3) The "two roughing, three cleaning, and two scavenging" flotation process is adopted. The tailings from the first roughing stage enter the second roughing stage. The froth from the first and second roughing stages is cleaned three times to produce crude silver concentrate. The tailings after the second roughing stage enter the scavenging stage and are scavenged twice to produce flotation tailings. The proportion of -0.074mm particles is 85%. The composite collector is prepared by mixing 5 parts of sodium dimethyl dithiocarbamate and 2 parts of butylated dimethylamine black powder. The dosage range of the mixed collector during the flotation process is 50g / t to 750g / t, the dosage range of sodium sulfide is 250g / t to 400g / t, and the dosage range of pine oil is 15g / t to 60g / t.

[0033] (4) The flotation tailings are microwave activated and then sent to a rotary kiln for roasting. The tailings are mixed and roasted in a weight ratio of 1:0.25:0.10. The microwave frequency is 4GHz and the processing time is 5min.

[0034] (5) Dust is removed from the roasting flue gas using a bag filter, and valuable metals zinc and indium are recovered from the flue gas. The roasting flue gas is treated to meet the national standard GB 25466-2010 for emission, and the kiln slag meets the national standard GB / T37785-2019 for sale.

[0035] In this embodiment, after the above steps, the crude silver concentrate contains 2613.56 g / t of silver, with a recovery rate of 82.26%. The flue dust contains 992 g of Zn and 9.35 g of In, with a Zn recovery rate of 98.21% and an indium recovery rate of 93.5%. The main chemical components and mass percentages of the kiln slag are: Zn 0.21%, In 0.018%, Fe 20.08%, CaO 13.54%, and SiO2 12.56%.

[0036] Example 3

[0037] This embodiment is another example of the method for comprehensively recovering valuable metals from zinc leaching hazardous waste residue according to the present invention. The tin-zinc smelting hazardous waste residue used in this embodiment is leaching hazardous waste residue stockpiled in a certain area of ​​Guangxi. The main chemical components and their mass percentage content in the hazardous waste residue are: Zn 11.39%, In 0.097%, Fe 18.64%, CaO 8.96%, SiO2 4.89%, and silver content 230.11 g / t. The recovery process of this method includes the following steps:

[0038] (1) After 10 kg of leaching residue is filtered, it is fed into the grinding operation with a grinding concentration of 50%. During the grinding process, a mixed inhibitor is added. The mixed inhibitor is composed of 3 parts calcium oxide and 0.5 parts sodium hexametaphosphate.

[0039] (2) The qualified grinding particles are sent to flotation after ultrasonic activation treatment. The ultrasonic treatment time is 3 minutes and the frequency is 30KHz.

[0040] (3) A "two-roughing, three-cleansing, two-scavenging" flotation process is adopted. The tailings from the first roughing stage enter the second roughing stage. The froth from the first and second roughing stages is cleaned three times to produce crude silver concentrate. The tailings after the second roughing stage enter the scavenging stage and are scavenged twice to produce flotation tailings. The -0.074mm particle size accounts for 82%, and is prepared by compounding 6 parts of sodium dimethyl dithiocarbamate and 3 parts of butylated dimethyl sulfide. The dosage range of the composite collector during the flotation process is 50g / t to 800g / t, the dosage range of sodium sulfide is 250g / t to 480g / t, and the dosage range of pine oil is 15g / t to 75g / t.

[0041] (4) The flotation tailings are microwave activated and then sent to a rotary kiln for roasting. The tailings are mixed and roasted in a weight ratio of 1:0.30:0.1. The microwave frequency is 4GHz and the microwave treatment time is 5min.

[0042] (5) Dust is removed from the roasting flue gas using a bag filter, and valuable metals zinc and indium are recovered from the flue gas. The roasting flue gas is treated to meet the national standard GB 25466-2010 for emission, and the kiln slag meets the national standard GB / T37785-2019 for sale.

[0043] In this embodiment, after the above steps, the crude silver concentrate contains 3950.60 g / t of silver, with a recovery rate of 84.46%. The flue dust contains 1118.8 g of Zn and 9.2 g of In, with a Zn recovery rate of 98.22% and an indium recovery rate of 94.84%. The main chemical components and mass percentages of the kiln slag are: Zn 0.19%, In 0.014%, Fe 28.25%, and CaO 8.63%.

Claims

1. A method for integrated recovery of valuable metals from zinc leaching hazardous waste residue, characterized in that, The main chemical components and mass percentage in the hazardous waste slag are: Zn 8.62%~11.39%, In 0.056%~0.10%, Fe 17.60%~24.11%, CaO 4.62%~8.96%, SiO2 4.24%~6.00%, and silver 70.36g / t~230.11g / t, including the following steps: (1) the zinc leaching hazardous waste slag is sent to grinding operation after pressure filtration, and a mixed depressant composed of 3~4 parts of calcium oxide and 0.5~1 part of sodium hexametaphosphate by mass is added in the grinding process; (2) the qualified particle size of grinding is sent to flotation after ultrasonic activation treatment, the ultrasonic frequency is 30KHz, and the ultrasonic action time is 3min; (3) a "two roughing-three cleaning-two scavenging" flotation process is adopted to obtain a rough silver concentrate, a composite collector obtained by compounding 4~6 parts of sodium dimethyl dithiocarbamate and 1~3 parts of ammonium black medicine is added in the flotation process; the composite collector dosage range is 50g / t~800g / t, the sodium sulfide dosage range is 250g / t~480g / t, and the pine oil dosage range is 15g / t~75.0g / t; wherein the flotation process is: the tailings of the first roughing enter the second roughing; the foam of the first and second roughing concentrates is treated by three cleaning to produce a rough silver concentrate; the tailings after the second roughing enter the scavenging process, and the flotation tailings are produced by two times of scavenging; (4) the flotation tailings are mixed in a ratio of tailings: anthracite: coke = 1:0.20~0.30:0.1~0.15 after pressure filtration, and are sent to a rotary kiln for roasting after microwave activation treatment, wherein the microwave frequency is 4GHz, the treatment time is 5~10min, the roasting temperature is 1020℃~1100℃, and the roasting time is 0.5~1h; (5) the dust of roasting is recovered by a bag filter, zinc and indium in the dust are recovered, and the flue gas is discharged; the grinding medium in step (1) is steel ball, and the grinding concentration is 50%~60%; the qualified particle size of grinding in step (2) is -0.074mm particle size, and the proportion is 75%~88%; the main chemical components and mass percentage in the kiln slag in step (5) are: Zn 0.19%~0.25%, In 0.014%~0.018%, Fe 20.08%~28.25%, and CaO 8.63%~13.65%.

2. The method according to claim 1, characterized in that, the outlet flue gas temperature in step (4) is 620℃~750℃.

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