Metal-containing solid waste treatment process and application

Abstract

The invention provides a metal-containing solid waste treatment process and application. According to the process, harmless and waste-free resourceful treatment can be carried out on metal-containing solid wastes including but not limited to metal-containing oil refining waste catalysts, metal-containing FCC waste catalysts, sludge rich in various metals, waste lithium ion batteries and the like; the problems that in the prior art, a traditional wet process is used for treating the metal-containing industrial solid waste, the water consumption is large, and the discharge amount of high-salinity wastewater is large are solved, water resources are saved, the treatment process is simple, a special treatment device does not need to be researched and developed, the treatment cost of the metal-containing solid waste is reduced, and the environment is protected. And the method is an environment-friendly metal-containing solid waste treatment process.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial metal-containing solid waste treatment and resource recovery, and particularly relates to a treatment process and application of metal-containing solid waste. Background Art

[0002] With the development of industrial production, the quantity of industrial solid waste containing metals is increasing day by day, especially the industrial solid waste emissions from industries such as metallurgy, power plants, and coal chemical industries are the largest. At present, the most common treatment method for most industrial solid wastes is passive stacking. However, passive stacking of industrial solid wastes not only occupies a large amount of land, but also various metal elements such as copper, lead, zinc, chromium, cadmium, arsenic, and mercury contained in bulk industrial solid wastes will flow into nearby rivers or seep into the ground with rainwater, seriously polluting the environment and human health. Therefore, industrial solid wastes need to be treated by appropriate processes and the resource utilization of industrial solid wastes should be realized. With the increasingly serious environmental pollution, the state has adopted more and more stringent environmental protection policies, and the industries that can resource-utilize industrial solid wastes will enter a golden development period. At the same time, the investment value of downstream fields such as resource treatment equipment for industrial solid wastes and methods for resource recycling will become increasingly apparent.

[0003] At present, the wet process for treating industrial solid waste containing metals is widely used due to its characteristics such as low energy consumption, low carbon emissions, and low cost. However, the wet process has a large water consumption, and the process of separating and recovering metals in the subsequent metal leaching solution is complex, generating a large amount of high-salinity wastewater, resulting in extremely high treatment costs for the downstream leaching solution. Therefore, how to solve the problems of large water consumption and large discharge of high-salinity wastewater in the wet process is the key to reducing the cost of the wet process. Summary of the Invention

[0004] In order to solve the problems of large water consumption and large discharge of high-salinity wastewater in the treatment of industrial solid waste containing metals using the traditional wet process in the prior art, the object of the present invention is to provide a treatment process and application of metal-containing solid waste.

[0005] The present invention provides a treatment process of metal-containing solid waste, which comprises the following steps:

[0006] 1) Wet-treat the metal-containing solid waste to obtain a wet-treated product;

[0007] 2) Perform a first solid-liquid separation on the wet-treated product to recover the first solid and obtain a first treatment liquid;

[0008] 3) Perform a fractional precipitation treatment on the first treatment liquid, and the total number of stages of the fractional precipitation treatment is not less than 1; after each stage of precipitation treatment, perform a second solid-liquid separation to obtain a second solid and a second treatment liquid;

[0009] 4) Filter-press the second solid obtained from each stage of precipitation treatment. After the third solid-liquid separation, recover the third solid to obtain the third treatment liquid;

[0010] 5) Combine the third treatment liquid generated by filter-pressing the second solid obtained from each stage of precipitation treatment except the last stage with the second treatment liquid obtained from the precipitation treatment of the same stage to obtain the fourth treatment liquid, and perform the next-stage precipitation;

[0011] 6) Combine the second treatment liquid obtained from the last-stage precipitation treatment with the third treatment liquid generated by filter-pressing the second solid obtained from the last-stage precipitation treatment to obtain the fifth treatment liquid;

[0012] 7) Condense the fifth treatment liquid. After the fourth solid-liquid separation, recover the fourth solid to obtain the sixth treatment liquid;

[0013] 8) Reuse the sixth treatment liquid for the wet treatment.

[0014] In a specific embodiment of the present invention, in step 1), sulfuric acid is used to perform metal sulfuric acid leaching on the metal-containing solid waste to achieve the wet treatment; or

[0015] Metal microbial leaching of the metal-containing solid waste is performed using Thiobacillus leaching solution to achieve the wet treatment.

[0016] In a specific embodiment of the present invention, in step 3), the pH is adjusted to alkaline to achieve the fractional precipitation treatment; and / or the pH is adjusted with sodium base; and / or the second solid is a metal precipitate; and / or

[0017] In step 4), the third solid is a filter-pressed metal precipitate; and / or

[0018] The fifth treatment liquid and the sixth treatment liquid are independently sodium sulfate solutions; and / or

[0019] In step 7), the fourth solid is sodium sulfate; and / or the concentration of sodium sulfate in the sixth treatment liquid is less than 50 g / L.

[0020] In a specific embodiment of the present invention, the sodium base is sodium hydroxide and / or sodium carbonate; and / or

[0021] The metal precipitate is metal hydroxide and / or metal carbonate.

[0022] In a specific embodiment of the present invention, in step 7), when the concentration of sodium sulfate in the fifth treatment liquid is less than 200 g / L, first concentrate the fifth treatment liquid to a sodium sulfate concentration of not less than 200 g / L, and then perform the condensation.

[0023] In a specific embodiment of the present invention, the percentage of the mass of the metal-containing solid waste to the volume of the sulfuric acid and the percentage of the mass of the metal-containing solid waste to the volume of the leachate of the Thiobacillus bacteria are independently 10% to 40%;

[0024] Preferably, the percentage of the mass of the metal-containing solid waste to the volume of the sulfuric acid is 20% to 40%; or

[0025] the percentage of the mass of the metal-containing solid waste to the volume of the leachate of the Thiobacillus bacteria is 10% to 20%.

[0026] In a specific embodiment of the present invention, the sulfuric acid is an aqueous sulfuric acid solution; and / or

[0027] In the leachate of the Thiobacillus bacteria, the strain density of the Thiobacillus bacteria is 5×10 9 to 8×10 9 cells / mL.

[0028] In a specific embodiment of the present invention, the pH of the aqueous sulfuric acid solution is 0.5 to 0.6; and / or

[0029] The Thiobacillus bacteria include Acidithiobacillus thiooxidans and / or Acidithiobacillus caldus.

[0030] In a specific embodiment of the present invention, the treatment duration of the metal sulfuric acid leaching is not less than 24 h; and / or

[0031] The treatment duration of the metal microbial leaching is 96 to 120 h.

[0032] According to a specific embodiment of the present invention, the metal sulfuric acid leaching is carried out at a temperature not lower than 10°C (for example, at a room temperature of 25°C); and / or

[0033] The metal microbial leaching is carried out at 25 to 37°C.

[0034] In a specific embodiment of the present invention, the temperature of the condensation is 0 to 5°C; and / or

[0035] The pressure of the concentration is 0.3 to 0.9 MPa;

[0036] Preferably, the temperature of the condensation is 0 to 1°C; and / or

[0037] The pressure of the concentration is 0.4 to 0.5 MPa.

[0038] Application of the process according to the present invention in the waste-free resource treatment of metal-containing solid waste.

[0039] In a specific embodiment of the present invention, the metal-containing solid waste includes smelting tailings, waste batteries, municipal sludge and waste catalysts.

[0040] It should be noted that the types of the above-listed metal-containing solid waste are not exhaustive, and the metal-containing solid waste referred to in the present invention includes but is not limited to the above-listed metal-containing solid waste.

[0041] According to a specific embodiment of the present invention, the wet treatment is carried out using a wet treatment tank or a bioleaching reactor; and / or

[0042] The first solid-liquid separation is carried out using any one of a sedimentation tank, a bag-type solid-liquid separation device and a centrifugal device; and / or

[0043] The fractional precipitation treatment and the second solid-liquid separation are carried out using a metal sedimentation tank equipped with a pH meter; and / or

[0044] The pressure filtration and the third solid-liquid separation are carried out using a pressure filtration device; and / or

[0045] The concentration is carried out using a high-pressure reverse osmosis salt concentration device; and / or

[0046] The condensation and the fourth solid-liquid separation are carried out using a cold trap; and / or

[0047] The sixth treatment liquid is collected using a water body reuse tank and reused for the wet treatment;

[0048] Preferably, the wet treatment tank is a PP barrel; and / or

[0049] The pressure filtration device is a filter press with a filter cloth, a filter paper or a filter membrane; and / or

[0050] The cold trap is a cold trap with a condensation crystal collection function;

[0051] Preferably, the metal sedimentation tank is also provided with a stirring device; and / or

[0052] The accuracy of the pH meter is ±0.02.

[0053] It should also be noted that the devices for carrying out the above steps are only simply listed to illustrate how the process provided by the present invention is implemented, and any device capable of achieving the treatment purpose of each step of the present invention can be used in the present invention.

[0054] Advantages of the present invention:

[0055] Aiming at the problems of large water consumption and large discharge of high-salinity wastewater in the treatment of metal-containing industrial solid waste by traditional wet processes in the prior art, the present invention provides a process for treating metal-containing solid waste and its application. The process first performs wet treatment on the metal-containing solid waste by metal sulfuric acid leaching or metal microbial leaching, transferring the metal in the metal-containing solid waste from the solid phase to the liquid phase. After the metal is removed from the metal-containing solid waste, it can be used for other industrial applications according to its own characteristics. The metal transferred to the liquid phase is then subjected to fractional precipitation by adding sodium alkali, and then transferred back to the solid phase by pressure filtration, transformed into metal carbonate and / or metal hydroxide to realize the recovery of metal resources in the metal-containing solid waste; the wet treatment, fractional precipitation and pressure filtration steps will generate sodium sulfate solution. After the sodium sulfate solution is condensed, high-purity sodium sulfate crystals can be collected to realize the recovery of sodium sulfate, and the low-concentration sodium sulfate solution generated by condensation is discharged into the water body reuse pool for the preparation of sulfuric acid aqueous solution or Thiobacillus leaching solution for wet treatment. The process provided by the present invention can perform harmless and waste-free resource treatment on metal-containing solid waste including but not limited to metal-containing refinery waste catalysts, metal-containing FCC waste catalysts, sludge rich in various metals, and waste lithium-ion batteries, remove the metal in the metal-containing solid waste, transform it into harmless industrial materials, efficiently recover various metals in the metal-containing solid waste, as well as the sodium salts generated during the treatment process, realize the reuse of treatment water, without the generation of solid waste and wastewater, solve the problems of large water consumption and large discharge of high-salinity wastewater in the treatment of metal-containing industrial solid waste by traditional wet processes in the prior art, save water resources, and the treatment process is simple, without the need to develop special treatment devices, reducing the treatment cost of metal-containing solid waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 Shows the process flow of the process for treating metal-containing solid waste provided by the present invention;

[0057] Figure 2 Shows Figure 1 the specific process of fractional precipitation treatment in DETAILED DESCRIPTION OF THE EMBODIMENTS

[0058] The present invention will be further described below in conjunction with embodiments, but the embodiments of the present invention are only exemplary descriptions, and this implementation method does not constitute a limitation to the present invention under any circumstances.

[0059] The following room temperature refers to 25 °C.

[0060] In combination with Figure 1 、 Figure 2 and the specific devices used in each treatment step, the specific process of treating metal-containing solid waste by the process for treating metal-containing solid waste provided by the present invention is described in detail.

[0061] (1) Wet treatment of metal-containing solid waste

[0062] In the present invention, the wet treatment is chemical wet treatment or biological wet treatment.

[0063] The following is a detailed description of chemical wet treatment and biological wet treatment respectively:

[0064] Chemical wet treatment of metal-containing solid waste: Add the metal-containing solid waste and sulfuric acid aqueous solution into a wet treatment pool (the mass of the metal-containing solid waste accounts for 10% to 40% of the volume of the sulfuric acid aqueous solution, such as 10%, 15%, 20%, 25%, 30%, 35%, 40%; preferably 20% to 40%). Adjust the pH by controlling the concentration of sulfuric acid in the sulfuric acid aqueous solution (preferably the pH of the sulfuric acid aqueous solution is 0.5 to 0.6), and carry out metal sulfuric acid leaching. React at a temperature not lower than 10 °C (such as room temperature) for not less than 24 h to obtain a chemical wet treatment product;

[0065] Biological wet treatment of metal-containing solid waste: The strain density of Thiobacillus in the Thiobacillus leaching solution is 5×10 9 to 8×10 9 cells / mL. Thiobacillus includes Acidithiobacillus thiooxidans and / or Acidithiobacillus caldus. Add the Thiobacillus leaching solution and the metal-containing solid waste (the mass of the metal-containing solid waste accounts for 10% to 40% of the volume of the Thiobacillus leaching solution, such as 10%, 15%, 20%, 25%, 30%, 35%, 40%; preferably 10% to 20%) into a biological leaching reactor for metal microbial leaching, and react for 96 to 120 h to obtain a biological wet treatment product; To ensure the activity of Thiobacillus, the metal biological leaching is carried out at 25 to 37 °C;

[0066] (2) Perform the first solid-liquid separation on the wet treatment product

[0067] Transfer the chemical wet treatment product into a solid-liquid separation device (such as a sedimentation tank, a bag-type solid-liquid separation device, and a centrifugal device; preferably a bag-type solid-liquid separation device) for the first solid-liquid separation, and separate for 2 h to obtain a first solid and a first treatment liquid (i.e., a sulfuric acid solution dissolved with metal); or

[0068] Transfer the biological wet treatment product into a solid-liquid separation device (such as a sedimentation tank, a bag-type solid-liquid separation device, and a centrifugal device; preferably a bag-type solid-liquid separation device) for the first solid-liquid separation, and separate for 2 h to obtain a first solid and a first treatment liquid (i.e., a Thiobacillus leaching solution dissolved with metal);

[0069] (3) Perform fractional precipitation on the first treatment liquid and pressure filtration on the second solid

[0070] After drying the first solid, it is recovered. The first treatment liquid is transferred to a metal sedimentation tank (equipped with a stirring device and a pH meter with a measurement accuracy of ±0.02 for precise pH control) for fractional precipitation treatment. The specific process is as follows: First, add the sodium base (such as sodium hydroxide or sodium carbonate) to adjust the pH and precipitate the first metal to complete the first-stage precipitation treatment; after the second solid-liquid separation in the metal sedimentation tank, obtain the first metal precipitate (i.e., the second solid) and the second treatment liquid; the first metal precipitate enters the pressure filtration device (a filter press with filter cloth, filter paper, or filter membrane) for the above-mentioned pressure filtration. After the third solid-liquid separation in the pressure filtration device, recover the first metal hydroxide or the first metal carbonate (i.e., the third solid), and the liquid obtained after pressure filtration (i.e., the third treatment liquid) is returned to the metal sedimentation tank and merged with the second treatment liquid obtained from the first-stage precipitation to form the fourth treatment liquid; then add the sodium base to the fourth treatment liquid to adjust the pH and precipitate the second metal to complete the second-stage precipitation treatment; after the second solid-liquid separation in the metal sedimentation tank, obtain the second metal precipitate (i.e., the second solid) and the second treatment liquid; the second metal precipitate enters the pressure filtration device for the above-mentioned pressure filtration. After the third solid-liquid separation in the pressure filtration device, recover the second metal hydroxide or the second metal carbonate (i.e., the third solid), and the liquid obtained by pressure filtration (i.e., the third treatment liquid) is returned to the metal sedimentation tank and merged with the second treatment liquid obtained from the second-stage precipitation to form the fourth treatment liquid; repeat the above method to collect different metal hydroxides or metal carbonates and achieve the recovery of different types of metals in the metal-containing solid waste. When the metal sedimentation tank completes the precipitation of the last metal (or two or more similar metals with almost the same pH required for precipitation) (i.e., the final-stage precipitation treatment), perform the second solid-liquid separation in the metal sedimentation tank to obtain the metal precipitate of the last metal (or two or more similar metals with almost the same pH required for precipitation) (i.e., the second solid) and the second treatment liquid; the metal precipitate of the last metal (or two or more similar metals with almost the same pH required for precipitation) enters the pressure filtration device for the above-mentioned pressure filtration. After the third solid-liquid separation in the pressure filtration device, recover the metal hydroxide or the metal carbonate of the last metal (or two or more similar metals with almost the same pH required for precipitation) (i.e., the third solid) and the obtained third treatment liquid; merge the third treatment liquid generated by pressure filtration of the second solid obtained from the final-stage precipitation and the second treatment liquid obtained from the final-stage precipitation to obtain the fifth treatment liquid (i.e., sodium sulfate solution);

[0071] (4) Condense sodium sulfate in the fifth treatment liquid

[0072] Judge whether to concentrate before condensation based on the concentration of sodium sulfate in the fifth treatment liquid:

[0073] When the concentration of sodium sulfate in the fifth treatment liquid is not less than 200 g / L, directly transfer the fifth treatment liquid into a cold trap (preferably a cold trap with a function of collecting condensed crystals), adjust the temperature to 0 to 5 °C (such as 0 °C, 1 °C, 2 °C, 3 °C, 4 °C, 5 °C, preferably 0 to 1 °C, such as 0 °C, 0.1 °C, 0.2 °C, 0.3 °C, 0.4 °C, 0.5 °C, 0.6 °C, 0.7 °C, 0.8 °C, 0.9 °C, 1 °C) for condensation. After the fourth solid-liquid separation, recover sodium sulfate crystals (i.e., the fourth solid) to obtain a sixth treatment liquid, in which the concentration of sodium sulfate is less than 50 g / L;

[0074] When the concentration of sodium sulfate in the fifth treatment liquid is less than 200 g / L, first transfer the fifth treatment liquid into a high-pressure reverse osmosis salt concentration device, set the pressure to 0.3 to 0.9 MPa (such as 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, preferably 0.4 to 0.5 MPa) for concentration. Water is generated during the concentration process. After the concentration is completed, the concentration of sodium sulfate in the fifth treatment liquid is not less than 200 g / L; then transfer the concentrated fifth treatment liquid into a cold trap, adjust the temperature to 0 to 5 °C (such as 0 °C, 1 °C, 2 °C, 3 °C, 4 °C, 5 °C; preferably 0 to 1 °C, such as 0 °C, 0.1 °C, 0.2 °C, 0.3 °C, 0.4 °C, 0.5 °C, 0.6 °C, 0.7 °C, 0.8 °C, 0.9 °C, 1 °C) for condensation. After the fourth solid-liquid separation, recover sodium sulfate crystals (i.e., the fourth solid) to obtain a sixth treatment liquid, in which the concentration of sodium sulfate is less than 50 g / L;

[0075] (5) Collect the sixth treatment liquid and the water generated during the concentration process (if the concentration step is carried out before condensation) together into a water body reuse pool for preparing the liquid used in the wet treatment (specifically sulfuric acid aqueous solution or Acidithiobacillus leaching solution) and reuse it in the wet treatment step.

[0076] Example 1

[0077] Use the metal-containing solid waste treatment process provided by the present invention to treat the metal-containing refinery waste catalyst. The information on the wet treatment method and the metal-containing refinery waste catalyst selected is as follows:

[0078] ⅰ Wet treatment method: Metal microbial leaching;

[0079] ⅱ Microbial species: Acidithiobacillus thiooxidans;

[0080] ⅲ Preparation of Acidithiobacillus thiooxidans leaching solution

[0081] Preparation of Thiobacillus leaching liquid medium: Dissolve 1.5 g / L of (NH4)2SO4, 1 g / L of KH2PO4, 0.2 g / L of MgSO4·7H2O, 0.2 g / L of CaCl2 and 0.01 g / L of FeSO4 into distilled water, add 2 mL of 2 mol / L sulfuric acid solution to adjust the pH to 2.0, sterilize at 110 °C for 20 min, and then add 8 g / L of sulfur powder to obtain the Thiobacillus leaching liquid medium;

[0082] Preparation of Thiobacillus thiooxidans leaching solution: Add Thiobacillus thiooxidans to the Thiobacillus leaching liquid medium, mix evenly to obtain a Thiobacillus thiooxidans leaching solution with an initial pH of 2.0; among them, the strain density of Thiobacillus thiooxidans is 5×10 9 cells / mL;

[0083] ⅳ Metal-containing refinery waste catalyst: Obtained from a certain refinery, the types and contents of metals contained therein are 2.8 mg / g of Ni, 5.6 mg / g of V, 12.9 mg / g of La and 14.5 mg / g of Ce;

[0084] ⅴ Implement the treatment process for metal-containing solid waste:

[0085] (1) According to the solid-liquid mass-volume ratio of 20% (kg / L), weigh 6 kg of metal-containing refinery catalyst, add it to a 50 L-capacity biological leaching reactor equipped with 30 L of Thiobacillus thiooxidans leaching solution for metal extraction, react at 37 °C for 120 h to obtain a wet treatment product;

[0086] (2) Transfer the wet treatment product to a bag-type solid-liquid separation device for the first solid-liquid separation. After 2 h of separation, obtain the first solid and the first treatment liquid;

[0087] (3) Dry the first solid obtained in step (2) at 70 °C to obtain the treated waste catalyst for recovery; the first treatment liquid is transferred to a metal sedimentation tank (equipped with a stirring device and a pH meter with a measurement accuracy of ±0.02 for precise pH control) for fractional precipitation: first add sodium hydroxide to adjust the pH to 6.92 to precipitate metal V to complete the first-stage precipitation; perform the second solid-liquid separation in the metal sedimentation tank to obtain V(OH)3 precipitate (i.e., the second solid) and the second treatment liquid; the V(OH)3 precipitate enters a filter press with filter paper for pressure filtration. After the third solid-liquid separation in the filter press, recover the pressure-filtered V(OH)3 (i.e., the third solid), and the liquid obtained after pressure filtration (i.e., the third treatment liquid) is returned to the metal sedimentation tank and merged with the second treatment liquid obtained from the first-stage precipitation to form the fourth treatment liquid;

[0088] Then, sodium carbonate is added to the fourth treatment liquid derived from the primary precipitation to adjust the pH to 8.35 to precipitate metallic Ni, completing the secondary precipitation; the second solid-liquid separation is carried out in a metal sedimentation tank to obtain NiCO3 precipitate (i.e., the second solid) and the second treatment liquid; the NiCO3 precipitate enters a filter press with filter paper for pressure filtration, and after the third solid-liquid separation in the filter press, the pressure-filtered NiCO3 (i.e., the third solid) is recovered, while the liquid obtained by pressure filtration (i.e., the third treatment liquid) is returned to the metal sedimentation tank and merged with the second treatment liquid obtained from the secondary precipitation to form the fourth treatment liquid;

[0089] Next, sodium hydroxide is added to the fourth treatment liquid derived from the secondary precipitation to adjust the pH to 8.83 to precipitate metallic La and metallic Ce, completing the final precipitation; the second solid-liquid separation is carried out in a metal sedimentation tank to obtain the second solid (i.e., a mixture of La(OH)3 precipitate and Ce(OH)3 precipitate) and the second treatment liquid; the La(OH)3 precipitate and Ce(OH)3 precipitate enter a filter press with filter paper for pressure filtration, and after the third solid-liquid separation in the filter press, the third solid (i.e., a mixture of the pressure-filtered La(OH)3 precipitate and Ce(OH)3 precipitate) is recovered, while the liquid obtained by pressure filtration (i.e., the third treatment liquid) is returned to the metal sedimentation tank and merged with the second treatment liquid obtained from the final precipitation to form the fifth treatment liquid (where the concentration of sodium sulfate is 24 g / L);

[0090] (4) The fifth treatment liquid obtained in step (3) is discharged into a high-pressure reverse osmosis salt concentration device, and the pressure is set to 0.5 MPa for concentration. After concentration, the concentration of sodium sulfate in the fifth treatment liquid is 260 g / L. In addition, the fifth treatment liquid also contains a small amount of sodium carbonate; the concentrated fifth treatment liquid is transferred to a cold trap with a temperature set at 0.7 °C and having a function of collecting condensed crystals for condensation. After 6 h, a large amount of sodium sulfate crystals precipitate at the bottom, and the fourth solid-liquid separation is carried out in the cold trap to obtain sodium sulfate crystals (i.e., the fourth solid) and the sixth treatment liquid (where the concentration of sodium sulfate is less than 50 g / L); the sodium sulfate crystals are dried at 70 °C and then recovered;

[0091] (5) The sixth treatment liquid obtained in step (4) and the water generated during the concentration process are discharged into a water reuse pool together and continue to be used for preparing the Thiobacillus thiooxidans leaching solution to carry out metal leaching on the next batch of metal-containing refinery waste catalysts in a biological leaching reactor. After multiple cycles of treatment, no decrease in the biological leaching efficiency is observed.

[0092] Test Example 1

[0093] During the treatment process of Example 1, the precipitation rates of Ni, V, La, and Ce in step (3), the purities of the recovered NiCO3, V(OH)3, La2(OH)3, and Ce(OH)3, and the purity of the sodium sulfate recovered in step (5) are measured;

[0094] Metal precipitation rate = 1 - (content of a certain metal in the fifth treatment liquid / content of the same metal in the first treatment liquid) × 100%; specific results are shown in Table 1.

[0095] Table 1. Precipitation rate and purity in Example 1

[0096]

[0097] Combined with the experimental results in Example 1 and Table 1, it can be seen that the precipitation rates of Ni, V, La, and Ce in the first treatment liquid are all above 95%, and the precipitation rate of Ni even reaches 100% (that is, no Ni is detected in the fifth treatment liquid), indicating that the metal microbial leaching step removes most of the Ni, V, La, and Ce in the metal-containing refinery waste catalyst, transforming it from a toxic and harmful solid waste into a resource that can be recycled in industrial production, such as for making building materials or cement, etc.; in the fractional precipitation process, high-purity NiCO3, V(OH)3, La(OH)3, and Ce(OH)3 are obtained by pressure filtration. The purity of these metal carbonates or metal hydroxides is at least still above 75% and up to nearly 96%, indicating that the present invention effectively recovers the Ni, V, La, and Ce metal resources in the metal-containing refinery waste catalyst through fractional precipitation and pressure filtration, and the obtained high-purity metal carbonates are more conducive to their other industrial applications; during the treatment process, the sodium sulfate solution generated is concentrated and condensed, and high-purity sodium sulfate crystals are collected. The low-concentration sodium sulfate solution (where the concentration of sodium sulfate is lower than 50 g / L) generated after the condensation and precipitation of sodium sulfate is transferred to the water reuse pool to continue preparing the Thiobacillus thiooxidans leaching solution for the treatment of the next batch of metal-containing refinery waste catalysts.

[0098] Example 2

[0099] The metal-containing refinery waste catalyst is treated using the process for metal-containing solid waste provided by the present invention. The wet treatment method and information on the metal-containing refinery waste catalyst selected are as follows:

[0100] ⅰ Wet treatment method: metal sulfuric acid leaching;

[0101] ⅱ Sulfuric acid aqueous solution: pH is 0.6;

[0102] ⅲ Metal-containing refinery waste catalyst: the same as in Example 1;

[0103] ⅳ Implement the process for metal-containing solid waste treatment:

[0104] (1) Weigh 9 kg of metal-containing oil refining catalyst according to the solid-liquid mass-volume ratio of 30% (kg / L), add it to a 50 L capacity PP barrel containing 30 L of sulfuric acid aqueous solution for metal leaching. The initial pH is 0.6, and react at room temperature for 24 h to obtain a wet-process treatment product;

[0105] (2) The same as Example 1;

[0106] (3) The same as Example 1, and the concentration of sodium sulfate in the fifth treatment liquid obtained is 38.7 g / L;

[0107] (4) Drain the fifth treatment liquid obtained in step (3) into a high-pressure reverse osmosis salt concentration device, set the pressure to 0.4 MPa for concentration. After concentration, the concentration of sodium sulfate in the fifth treatment liquid is 220 g / L. In addition, the fifth treatment liquid also contains a small amount of sodium carbonate; transfer the concentrated fifth treatment liquid into a cold trap with a temperature set at 0.6 °C and having a function of collecting condensed crystals for condensation. After 6 h, a large amount of sodium sulfate crystals precipitate at the bottom. Perform the fourth solid-liquid separation in the cold trap to obtain sodium sulfate crystals (i.e., the fourth solid) and the sixth treatment liquid (where the concentration of sodium sulfate is less than 50 g / L); dry the sodium sulfate crystals at 70 °C and then recycle them;

[0108] (5) Drain the sixth treatment liquid obtained in step (4) into a water reuse pool and continue to be used for preparing sulfuric acid aqueous solution to perform metal leaching on the next batch of metal-containing oil refining waste catalysts in the PP barrel. After multiple cycle treatments, no decrease in treatment efficiency is observed.

[0109] Test Example 2

[0110] During the treatment process of Example 2, measure the precipitation rates of Ni, V, La, and Ce in step (3) and the purity of the sodium sulfate recovered in step (5);

[0111] Metal precipitation rate = 1 - (content of a certain metal in the fifth treatment liquid / content of a certain metal in the first treatment liquid) × 100%; The specific results are shown in Table 2.

[0112] Table 2. Precipitation rates and purities in Example 2

[0113]

[0114] Combined with the experimental results in Example 2 and Table 2, it can be seen that the precipitation rates of Ni, V, La, and Ce in the first treatment solution are all above 93%. The precipitation rate of Ni is the highest, specifically 99.5%, indicating that most of the Ni, V, La, and Ce in the metal-containing refinery waste catalyst are removed by sulfuric acid leaching, transforming it from a toxic and harmful solid waste into a resource that can be recycled in industrial production, such as for making building materials, cement, etc.; in the fractional precipitation process, NiCO3, V(OH)3, La(OH)3, and Ce(OH)3 are obtained by pressure filtration, realizing the effective recovery of Ni, V, La, and Ce metal resources in the metal-containing refinery waste catalyst. The obtained NiCO3, V(OH)3, La(OH)3, and Ce(OH)3 can be used for other industrial applications; the sodium sulfate solution generated during the treatment process is concentrated and condensed, and sodium sulfate crystals with a purity of 92.6% are collected. The low-concentration sodium sulfate solution with a sodium sulfate concentration lower than 50 g / L generated after the condensation and precipitation of sodium sulfate is transferred to the water reuse pool to continue preparing sulfuric acid aqueous solution for the metal sulfuric acid leaching of the next batch of metal-containing refinery waste catalyst.

[0115] Example 1 and Example 2 illustrate that the metal-containing solid waste treatment process provided by the present invention can achieve efficient and harmless resource treatment of the metal-containing refinery waste catalyst regardless of whether metal sulfuric acid leaching or metal microbial leaching is used in the wet treatment: the waste catalyst, metal carbonate, metal hydroxide, and sodium sulfate obtained during the treatment process can all be used for other industrial applications, without generating solid waste; the water used for preparing the Thiobacillus thiooxidans leachate and the water used for preparing the sulfuric acid aqueous solution are recycled, without generating wastewater, saving water resources, and solving the problems of large water consumption and large discharge of high-salinity wastewater existing in the wet treatment of metal-containing solid waste in the prior art. It is an environmentally friendly metal-containing solid waste treatment process.

[0116] Example 3

[0117] The metal-containing FCC waste catalyst is treated using the metal-containing solid waste treatment process provided by the present invention (mainly treating the rare earth metals therein). The selected wet treatment method and the information of the metal-containing FCC waste catalyst are as follows:

[0118] ⅰ Wet treatment method: Metal sulfuric acid leaching;

[0119] ⅱ Sulfuric acid aqueous solution: pH is 0.5;

[0120] ⅲ FCC spent catalyst containing metals: taken from the FCC unit of a refinery, the types and contents of rare earth metals contained therein are 21.3 mg / g of La and 34.2 mg / g of Ce; among them, La and Ce are similar metals, and the pH values of precipitation are almost the same, and La and Ce are also used as a mixture industrially. Therefore, in this example, La and Ce are directly precipitated together;

[0121] ⅳ Implement the treatment process for solid waste containing metals:

[0122] (1) According to the solid-liquid mass-volume ratio of 40% (kg / L), weigh 12 kg of FCC spent catalyst containing metals, add it to a 50 L capacity PP bucket filled with 30 L of sulfuric acid aqueous solution for metal leaching. The initial pH is 0.5, and the reaction is carried out at room temperature for 24 h to obtain a wet treatment product;

[0123] (2) Transfer the wet treatment product to a bag-type solid-liquid separation device for the first solid-liquid separation. After 2 h of separation, obtain the first solid and the first treatment liquid;

[0124] (3) Dry the first solid obtained in step (2) at 100 °C to recover the treated FCC spent catalyst; the first treatment liquid is transferred to a metal precipitation device for fractional precipitation: first add sodium hydroxide to adjust the pH to 8.83 to precipitate La and Ce metals and complete the final precipitation; in the metal precipitation tank, perform the second solid-liquid separation to obtain a mixture of La(OH)3 precipitate and Ce(OH)3 precipitate (i.e., the second solid) and the second treatment liquid; the La(OH)3 precipitate and Ce(OH)3 precipitate enter a filter press with a filter cloth for pressure filtration. After the third solid-liquid separation in the filter press, recover the pressure-filtered La(OH)3 precipitate and Ce(OH)3 precipitate (i.e., the third solid), and the liquid obtained after pressure filtration (i.e., the third treatment liquid) is returned to the metal precipitation tank to be combined with the second treatment liquid obtained from the final precipitation to form the fifth treatment liquid (the concentration of sodium sulfate therein is 19.6 g / L);

[0125] (4) Drain the fifth treatment liquid obtained in step (3) into a high-pressure reverse osmosis salt concentration device, set the pressure to 0.4 MPa for concentration, and the concentration of sodium sulfate in the concentrated fifth treatment liquid is 230 g / L; transfer the concentrated fifth treatment liquid to a cold trap with a temperature set at 0.7 °C and having a function of collecting condensed crystals for condensation. After 6 h, a large amount of sodium sulfate crystals precipitate at the bottom. Perform the fourth solid-liquid separation in the cold trap to obtain sodium sulfate crystals (i.e., the fourth solid) and the sixth treatment liquid (the concentration of sodium sulfate therein is less than 50 g / L); dry the sodium sulfate crystals at 100 °C and then recover them;

[0126] (5) The sixth treatment liquid obtained in step (4) is discharged into the water reuse pool and continues to be used for preparing the sulfuric acid aqueous solution to perform metal extraction on the next batch of metal-containing FCC spent catalysts in a PP bucket. After multiple cycles of treatment, no decrease in treatment efficiency is observed.

[0127] Test Example 3

[0128] During the treatment process of Example 3, the removal rates of La and Ce in step (2), the precipitation rates of La and Ce in step (3), and the purity of the sodium sulfate recovered in step (5) are measured;

[0129] Metal removal rate = 100% - (content of a certain metal in the first solid / initial content of a certain metal in the metal-containing FCC spent catalyst) × 100%;

[0130] Metal precipitation rate = 1 - (content of a certain metal in the fifth treatment liquid / content of a certain metal in the first treatment liquid) × 100%; The specific results are shown in Table 3.

[0131] Table 3. Precipitation rates and purities in Example 3

[0132]

[0133] Combined with the experimental results in Example 3 and Table 3, it can be seen that the removal rates of the rare earth metals La and Ce in the metal-containing FCC spent catalyst are both above 69%. The removal rate of La is relatively high, specifically 74.5%, indicating that most of La and Ce in the metal-containing FCC spent catalyst are removed by sulfuric acid leaching of metals, making the metal-containing FCC spent catalyst transformed into a harmless FCC spent catalyst, which can be used for the production of high-aluminum kaolin, proppants for fracturing, etc.; the precipitation rates of La and Ce in the first treatment liquid are both 100% (that is, no La and Ce are detected in the fifth treatment liquid). The fractional precipitation transfers all La and Ce in the first treatment liquid to the solid phase for metal recovery. La(OH)3 and Ce(OH)3 are obtained by pressure filtration, realizing the effective recovery of La and Ce metal resources in the metal-containing FCC spent catalyst; after the sodium sulfate solution generated during the treatment process is condensed, high-purity sodium sulfate crystals are collected, and the low-concentration sodium sulfate solution with a sodium sulfate concentration lower than 50 g / L generated after the sodium sulfate condenses and precipitates is transferred to the water reuse pool to continue preparing the sulfuric acid aqueous solution for metal sulfuric acid leaching of the next batch of metal-containing FCC spent catalysts.

[0134] Example 4

[0135] The metal-containing FCC spent catalyst is treated by using the metal-containing solid waste treatment process provided by the present invention (mainly treating the rare earth metals therein). The selected wet treatment method and information of the metal-containing FCC spent catalyst are as follows:

[0136] ⅰ Wet treatment method: metal microbial leaching;

[0137] ⅱ Microbial species: the same as in Example 1;

[0138] ⅲ Preparation of Thiobacillus thiooxidans leaching solution: the same as in Example 1;

[0139] ⅳ FCC waste catalyst containing metals: the same as in Example 3; among them, La and Ce are similar metals, the pH values of precipitation are almost the same, and La and Ce are also used as a mixture in industry. Therefore, La and Ce are directly precipitated together in this example;

[0140] ⅴ Process for treating metal-containing solid waste:

[0141] (1) According to the solid-liquid mass-volume ratio of 15% (kg / L), weigh 4.5 kg of FCC waste catalyst containing metals, add it to a 50 L-capacity biological leaching reactor filled with 30 L of Thiobacillus thiooxidans leaching solution, carry out metal leaching, and react at 25 °C for 120 h to obtain a wet treatment product;

[0142] (2) Transfer the wet treatment product into a bag-type solid-liquid separation device for the first solid-liquid separation. After 2 h of separation, obtain the first solid and the first treatment liquid;

[0143] (3) The same as in Example 3, the concentration of sodium sulfate in the fifth treatment liquid obtained is 69.8 g / L;

[0144] (4) Drain the fifth treatment liquid obtained in step (3) into a high-pressure reverse osmosis salt concentration device, set the pressure to 0.4 MPa for concentration. After concentration, the concentration of sodium sulfate in the fifth treatment liquid is 350 g / L; transfer the concentrated fifth treatment liquid into a cold trap with a set temperature of 0.7 °C and a function of collecting condensed crystals for condensation. After 6 h, a large amount of sodium sulfate crystals precipitate at the bottom. Carry out the fourth solid-liquid separation in the cold trap to obtain sodium sulfate crystals (i.e., the fourth solid) and the sixth treatment liquid (the concentration of sodium sulfate is less than 50 g / L). Dry the sodium sulfate crystals at 100 °C and recover them;

[0145] (5) Drain the sixth treatment liquid obtained in step (4) into the water reuse pool and continue to be used for preparing Thiobacillus thiooxidans leaching solution to carry out metal leaching on the next batch of FCC waste catalysts containing metals in the biological leaching reactor. After multiple cycles of treatment, no decrease in the biological leaching efficiency is observed.

[0146] Test Example 4

[0147] During the treatment process of Example 4, measure the removal rates of La and Ce in step (2), the precipitation rates of La and Ce in step (3), and the purity of the recovered sodium sulfate in step (5);

[0148] Metal removal rate = 100% - (content of a certain metal in the first solid / initial content of a certain metal in the FCC waste catalyst containing metal) × 100%;

[0149] Metal precipitation rate = 1 - (content of a certain metal in the fifth treatment liquid / content of a certain metal in the first treatment liquid) × 100%; The specific results are shown in Table 4.

[0150] Table 4. Precipitation rate and purity in Example 4

[0151]

[0152] Combined with the experimental results in Example 4 and Table 4, it can be seen that the removal rates of rare earth metals La and Ce in the FCC waste catalyst containing metal are both above 74%, and the removal rate of Ce is relatively high, specifically 77.7%. This indicates that most of La and Ce in the FCC waste catalyst containing metal are removed by sulfuric acid leaching of metals, converting the FCC waste catalyst containing metal into a harmless FCC waste catalyst, which can be used to make proppants for fracturing; the precipitation rates of La and Ce in the first treatment liquid are both 100% (that is, no La and Ce are detected in the fifth treatment liquid), and fractional precipitation transfers all La and Ce in the first treatment liquid to the solid phase for metal recovery. La(OH)3 and Ce(OH)3 are obtained by pressure filtration, realizing the effective recovery of La and Ce metal resources in the FCC waste catalyst containing metal; the sodium sulfate solution generated during the treatment process is concentrated and then condensed, and high-purity sodium sulfate crystals are collected. The low-concentration sodium sulfate solution with a sodium sulfate concentration lower than 50 g / L generated after the condensation and precipitation of sodium sulfate is transferred to the water reuse pool to continue preparing sulfuric acid aqueous solution for the metal sulfuric acid leaching of the next batch of FCC waste catalysts containing metal.

[0153] Examples 3 and 4 illustrate that the process for treating metal-containing solid waste provided by the present invention can achieve efficient and harmless resource treatment of the FCC waste catalyst containing metal whether the wet treatment therein uses metal sulfuric acid leaching or metal microbial leaching: the FCC waste catalyst, metal hydroxide, and sodium sulfate obtained during the treatment process can all be used for other industrial applications without generating solid waste; the water used for preparing the leaching solution of Thiobacillus thiooxidans and the water used for preparing the sulfuric acid aqueous solution are recycled without generating wastewater, saving water resources, and solving the problems of large water consumption and large discharge of high-salinity wastewater existing in the wet treatment of metal-containing solid waste in the prior art. It is an environmentally friendly process for treating metal-containing solid waste.

[0154] Example 5

[0155] The metal-containing solid waste treatment process provided by the present invention is used to treat sludge rich in various metals. The selected wet treatment method and information on the sludge rich in various metals are as follows:

[0156] ⅰ Wet treatment method: Metal microbial leaching;

[0157] ⅱ Microbial species: Acidithiobacillus caldus;

[0158] ⅲ Preparation of Acidithiobacillus caldus leachate:

[0159] Prepare a leaching liquid medium for Thiobacillus bacteria: Dissolve 1.5 g / L of (NH4)2SO4, 1 g / L of KH2PO4, 0.2 g / L of MgSO4·7H2O, 0.2 g / L of CaCl2, and 0.01 g / L of FeSO4 in distilled water, adjust the pH to 1.5 with sulfuric acid solution, sterilize at 110 °C for 20 min, and then add 8 g / L of sulfur powder to obtain a leaching liquid medium for Thiobacillus bacteria;

[0160] Prepare Acidithiobacillus caldus leachate: Add Acidithiobacillus caldus to the leaching liquid medium for Thiobacillus bacteria, mix evenly to obtain Acidithiobacillus caldus leachate with an initial pH of 1.5; among them, the cell density of Acidithiobacillus caldus is 8×10 9 cells / mL;

[0161] ⅵ Sludge rich in various metals: Sludge rich in various metals taken from an activated sludge plant and subjected to high-temperature treatment, with the metal types and contents being 67500 mg / kg of Fe, 830 mg / kg of Zn, 215 mg / kg of Cr, and 61.280 mg / kg of Ni;

[0162] ⅴ Implement the metal-containing solid waste treatment process:

[0163] (1) According to the solid-liquid mass-volume ratio of 10% (kg / L), weigh 3 kg of sludge rich in various metals, add it to a 50 L-capacity biological leaching reactor containing 30 L of Acidithiobacillus caldus leachate, carry out metal leaching, and react at 37 °C for 96 h to obtain a wet treatment product;

[0164] (2) Transfer the wet treatment product to a bag-type solid-liquid separation device for the first solid-liquid separation. After separating for 2 h, obtain the first solid and the first treatment liquid;

[0165] (3) Dry the first solid obtained in step (2) at 100 °C to obtain the treated sludge for recovery; the first treatment liquid is transferred to a metal precipitation tank (equipped with a stirring device and a pH meter with a measurement accuracy of ±0.02 for precise pH control) for fractional precipitation: first add sodium hydroxide to adjust the pH to 3.65 to precipitate metal Fe and complete the first-stage precipitation; after the second solid-liquid separation in the metal precipitation tank, obtain Fe(OH)3 precipitate (i.e., the second solid) and the second treatment liquid; the Fe(OH)3 precipitate enters a filter press with a filter membrane for pressure filtration, and after the third solid-liquid separation in the filter press, recover the pressure-filtered Fe(OH)3 precipitate (i.e., the third solid), and the liquid obtained after pressure filtration (i.e., the third treatment liquid) is returned to the metal precipitation tank and merged with the second treatment liquid obtained from the first-stage precipitation to form the fourth treatment liquid;

[0166] Then add sodium hydroxide to the fourth treatment liquid from the first-stage precipitation treatment to adjust the pH to 6.87 to precipitate metal Zn and complete the second-stage precipitation; after the second solid-liquid separation in the metal precipitation tank, obtain Zn(OH)2 precipitate (i.e., the second solid) and the second treatment liquid; the Zn(OH)2 precipitate enters a filter press with a filter membrane for pressure filtration, and after the third solid-liquid separation in the filter press, recover the pressure-filtered Zn(OH)2 precipitate (i.e., the third solid), and the liquid obtained after pressure filtration (i.e., the third treatment liquid) is returned to the metal precipitation tank and merged with the second treatment liquid obtained from the second-stage precipitation to form the fourth treatment liquid;

[0167] Next, add sodium carbonate to the fourth treatment liquid from the second-stage precipitation treatment to adjust the pH to 8.35 to precipitate metal Ni and complete the third-stage precipitation; after the second solid-liquid separation in the metal precipitation tank, obtain NiCO3 precipitate (i.e., the second solid) and the second treatment liquid; the NiCO3 precipitate enters a filter press with a filter membrane for pressure filtration, and after the third solid-liquid separation in the filter press, recover the pressure-filtered NiCO3 precipitate (i.e., the third solid), and the liquid obtained after pressure filtration (i.e., the third treatment liquid) is returned to the metal precipitation tank and merged with the second treatment liquid obtained from the third-stage precipitation to form the fourth treatment liquid;

[0168] Finally, add sodium carbonate to the fourth treatment liquid from the third-stage precipitation treatment to adjust the pH to 8.96 to precipitate metal Cr and complete the final-stage precipitation; after the second solid-liquid separation in the metal precipitation tank, obtain Cr(OH)3 precipitate (i.e., the second solid) and the second treatment liquid; the Cr(OH)3 precipitate enters a filter press with a filter membrane for pressure filtration, and after the third solid-liquid separation in the filter press, recover the pressure-filtered Cr(OH)3 precipitate (i.e., the third solid), and merge the liquid obtained after pressure filtration (i.e., the third treatment liquid) with the second treatment liquid obtained from the final-stage precipitation to form the fifth treatment liquid (i.e., sodium sulfate solution, where the concentration of sodium sulfate is 310 g / L);

[0169] (4) Transfer the fifth treatment liquid into a cold trap with a temperature set at 0.9 °C and having a function of condensing and collecting crystals. After 6 hours, a large amount of sodium sulfate crystals precipitate at the bottom. Conduct the fourth solid-liquid separation in the cold trap to obtain sodium sulfate crystals and the sixth treatment liquid (where the concentration of sodium sulfate is lower than 50 g / L). Dry the sodium sulfate crystals at 100 °C and then recycle them;

[0170] (5) Drain the sixth treatment liquid obtained in step (4) into the water reuse pool and continue to use it for preparing the Thiobacillus thermophilus leaching solution to leach metals from the next batch of sludge rich in various metals in the biological leaching reactor. After multiple cycles of treatment, no decrease in the biological leaching efficiency is observed.

[0171] Test Example 5

[0172] During the treatment process of Example 5, measure the precipitation rates of Fe, Zn, Cr, and Ni in step (3) and the purity of the sodium sulfate recovered in step (5);

[0173] Metal precipitation rate = 1 - (content of a certain metal in the fifth treatment liquid / content of a certain metal in the first treatment liquid) × 100%; The specific results are shown in Table 5.

[0174] Table 5. Precipitation rates and purities in Example 5

[0175]

[0176] Combined with the experimental results in Example 5 and Table 5, it can be seen that the precipitation rates of Fe, Zn, Cr, and Ni in the first treatment liquid are all above 84%. Fractional precipitation transfers most of the Fe, Zn, Cr, and Ni in the first treatment liquid to the solid phase for metal recovery. Hydroxides of Fe, Zn, Cr, and carbonate of Ni are obtained through pressure filtration, realizing the effective recovery of Fe, Zn, Cr, and Ni metal resources in the sludge rich in various metals; After the sodium sulfate solution generated during the treatment process is condensed, high-purity sodium sulfate crystals with a purity of 93.3% are collected, which is beneficial for its harmless utilization; The low-concentration sodium sulfate solution generated after the sodium sulfate condenses and precipitates is transferred into the water reuse pool and continues to be used to prepare the Thiobacillus thermophilus leaching solution for metal microbial leaching of the next batch of sludge rich in various metals.

[0177] Example 6

[0178] Use the metal-containing solid waste treatment process provided by the present invention to treat the sludge rich in various metals. The selected wet treatment method and information on the sludge rich in various metals are as follows:

[0179] ⅰ Wet treatment method: Metal sulfuric acid leaching;

[0180] ⅱ Sulfuric acid aqueous solution: pH is 0.5;

[0181] ⅲ Sludge rich in various metals: same as Example 5;

[0182] ⅳ Implement the metal-containing solid waste treatment process:

[0183] (1) Weigh 10.5 kg of sludge rich in various metals according to the solid-liquid mass-volume ratio of 35% (kg / L), add it to a 50 L capacity PP bucket containing 30 L of sulfuric acid aqueous solution, and carry out metal leaching. The initial pH is 0.5, and react for 24 h while stirring with a plastic paddle at room temperature to obtain a wet treatment product;

[0184] (2) Same as Example 5;

[0185] (3) Same as Example 5, and the concentration of sodium sulfate in the fifth treatment liquid obtained is 205 g / L;

[0186] (4) Transfer the fifth treatment liquid to a cold trap with a temperature set at 0.5 °C and having a function of collecting condensed crystals for condensation. After 5 h, a large amount of sodium sulfate crystals precipitate at the bottom. Carry out the fourth solid-liquid separation in the cold trap to obtain sodium sulfate crystals (i.e., the fourth solid) and the sixth treatment liquid (where the concentration of sodium sulfate is less than 50 g / L). Dry the sodium sulfate crystals at 100 °C and then recycle them;

[0187] (5) Drain the sixth treatment liquid obtained in step (4) into the water reuse pool, continue to use it for preparing sulfuric acid aqueous solution, and carry out metal leaching on the next batch of sludge rich in various metals in the PP bucket.

[0188] Test Example 6

[0189] During the treatment process of Example 6, measure the precipitation rates of Fe, Zn, Cr, and Ni in step (3) and the purity of the sodium sulfate recovered in step (5);

[0190] Metal precipitation rate = 1 - (content of a certain metal in the fifth treatment liquid / content of a certain metal in the first treatment liquid) × 100%; The specific results are shown in Table 6.

[0191] Table 6. Precipitation rates and purities in Example 6

[0192]

[0193] Combined with the experimental results in Example 6 and Table 6, it can be seen that the precipitation rates of Fe, Zn, Cr, and Ni in the first treatment solution are all above 87%. The fractional precipitation transfers most of the Fe, Zn, Cr, and Ni in the first treatment solution to the solid phase for metal recovery. Hydroxides of Fe, Zn, Cr, and carbonate of Ni are obtained through pressure filtration, realizing the effective recovery of metal resources of Fe, Zn, Cr, and Ni in the sludge rich in various metals. After the sodium sulfate solution generated during the treatment process is condensed, high-purity sodium sulfate crystals with a purity of 94.6% are collected, which is beneficial to its industrial application. The low-concentration sodium sulfate solution generated after the sodium sulfate is condensed and precipitated is transferred to the water reuse pool to continue preparing sulfuric acid aqueous solution for the metal sulfuric acid leaching of the next batch of sludge rich in various metals.

[0194] Examples 5 and 6 illustrate that the process for treating metal-containing solid waste provided by the present invention can achieve efficient and harmless resource treatment of sludge rich in various metals whether the wet treatment therein adopts metal sulfuric acid leaching or metal microbial leaching: The sludge, metal hydroxides, metal carbonates, and sodium sulfate obtained during the treatment process can all be used for other industrial applications without generating solid waste; The water used for preparing the Thiobacillus thermophilus leachate and the water used for preparing the sulfuric acid aqueous solution are recycled without generating wastewater, saving water resources, and solving the problems of large water consumption and large discharge of high-salinity wastewater existing in the wet treatment of metal-containing solid waste in the prior art. It is an environmentally friendly process for treating metal-containing solid waste.

[0195] Example 7

[0196] The process for treating metal-containing solid waste provided by the present invention is used to treat waste lithium-ion batteries. The selected wet treatment method and the information of the waste lithium-ion batteries are as follows:

[0197] ⅰ Wet treatment method: Metal sulfuric acid leaching;

[0198] ⅱ Sulfuric acid aqueous solution: pH is 0.5;

[0199] ⅲ Waste lithium-ion batteries: The waste lithium-ion batteries taken from a battery factory in Shenzhen are unloaded, disassembled, and crushed, which contain 351800 mg / kg of Co;

[0200] ⅳ Implement the process for treating metal-containing solid waste:

[0201] (1) According to the solid-liquid mass-volume ratio of 20% (kg / L), 6 kg of waste lithium-ion batteries are weighed and added to a 50 L capacity PP bucket containing 30 L of sulfuric acid aqueous solution for metal leaching. The initial pH is 0.5, and the reaction is carried out for 24 h while stirring with a plastic paddle at room temperature to obtain the wet treatment product;

[0202] (2) Transfer the wet treatment product into a bag-type solid-liquid separation device for the first solid-liquid separation. After 2 hours of separation, obtain the first solid and the first treatment liquid; dry the obtained first solid at 100 °C to obtain the treated waste lithium-ion battery for recycling;

[0203] (3) Transfer the first treatment liquid obtained in step (2) into a metal precipitation device for fractional precipitation: add sodium hydroxide to adjust the pH to 8.46 to precipitate metal Co and complete the final precipitation; perform a second solid-liquid separation in the metal precipitation tank to obtain Co(OH)₂ precipitate (i.e., the second solid) and the second treatment liquid; the Co(OH)₂ precipitate enters a filter press with a filter cloth for pressure filtration. After the third solid-liquid separation in the filter press, recover the pressure-filtered Co(OH)₂ precipitate (i.e., the third solid), and combine the liquid obtained by pressure filtration (i.e., the third treatment liquid) with the second treatment liquid obtained from the final precipitation to form the fifth treatment liquid (i.e., sodium sulfate solution, where the concentration of sodium sulfate is 96 g / L);

[0204] (4) Drain the fifth treatment liquid obtained in step (3) into a high-pressure reverse osmosis salt concentration device, set the pressure to 0.5 MPa for concentration, and the concentration of sodium sulfate in the concentrated fifth treatment liquid is 220 g / L; transfer the concentrated fifth treatment liquid into a cold trap with a temperature set at 0.7 °C and having a function of collecting condensed crystals for condensation. After 5 hours, a large amount of sodium sulfate crystals precipitate at the bottom. Perform a fourth solid-liquid separation in the cold trap to obtain sodium sulfate crystals and the sixth treatment liquid (where the concentration of sodium sulfate is less than 50 g / L), and dry the sodium sulfate crystals at 100 °C for recycling;

[0205] (5) Drain the sixth treatment liquid obtained in step (4) into a water reuse pool and continue to be used for preparing sulfuric acid aqueous solution to leach metals from the next batch of waste lithium-ion batteries in a PP bucket.

[0206] Test Example 7

[0207] During the treatment process of Example 7, determine the precipitation rate of Co in step (3) and the purity of the recovered sodium sulfate in step (5);

[0208] Metal precipitation rate = 1 - (content of a certain metal in the fifth treatment liquid / content of a certain metal in the first treatment liquid) × 100%; the specific results are shown in Table 7.

[0209] Table 7. Precipitation rate and purity in Example 7

[0210] substance item value / % Co precipitation rate 99.3 <![CDATA[Na2SO4]]> purity 98.6

[0211] Combined with the experimental results in Example 7 and Table 7, it can be seen that the precipitation rate of metal Co in the first treatment liquid is as high as 99.3%. The fractional precipitation transfers all the Co in the first treatment liquid to the solid phase, facilitating the recovery of Co. Co(OH)2 is obtained through pressure filtration, realizing the effective recovery of Co resources in waste lithium-ion batteries. The sodium sulfate solution generated during the treatment process is condensed to obtain sodium sulfate crystals with a purity of 98.6%. The low-concentration sodium sulfate solution with a sodium sulfate concentration lower than 50 g / L generated after the condensation and precipitation of sodium sulfate is transferred to the water reuse pool to continue preparing sulfuric acid aqueous solution for the metal sulfuric acid leaching of the next batch of waste lithium-ion batteries. The water used for preparing the sulfuric acid aqueous solution is recycled, without generating waste water, saving water resources, and solving the problems of large water consumption and large discharge of high-salinity waste water existing in the wet treatment of metal-containing solid waste in the prior art. It is an environmentally friendly process for treating metal-containing solid waste.

[0212] Although the present invention has been described with reference to specific embodiments, those skilled in the art should understand that various changes can be made without departing from the true spirit and scope of the present invention. In addition, various changes can be made to the main body, spirit, and scope of the present invention to adapt to specific situations, materials, material compositions, and methods. All such changes are included within the scope of the claims of the present invention.

Claims

1. A process for treating metal-containing solid waste, which comprises the following steps: 1) Wet-treat the metal-containing solid waste to obtain a wet-treatment product; 2) Perform a first solid-liquid separation on the wet-treatment product to recover the first solid and obtain a first treatment liquid; 3) Perform a fractional precipitation treatment on the first treatment liquid, and the total number of stages of the fractional precipitation treatment is not less than 1; After each stage of precipitation treatment, perform a second solid-liquid separation to obtain a second solid and a second treatment liquid; 4) Subject the second solid obtained from each stage of precipitation treatment to pressure filtration, and after a third solid-liquid separation, recover the third solid and obtain a third treatment liquid; 5) Combine the third treatment liquid generated by the pressure filtration of the second solid obtained from each stage of precipitation treatment except the last stage and the second treatment liquid obtained from the same-stage precipitation treatment to obtain a fourth treatment liquid, and perform the next-stage precipitation; 6) Combine the second treatment liquid obtained from the last-stage precipitation treatment and the third treatment liquid generated by the pressure filtration of the second solid obtained from the last-stage precipitation treatment to obtain a fifth treatment liquid; 7) Condense the fifth treatment liquid, and after a fourth solid-liquid separation, recover the fourth solid and obtain a sixth treatment liquid; 8) Reuse the sixth treatment liquid in the wet treatment.

2. The process according to claim 1, characterized in that, In step 1), use sulfuric acid to perform metal sulfuric acid leaching on the metal-containing solid waste to achieve the wet treatment; or Use a leaching solution of Thiobacillus bacteria to perform metal microbial leaching on the metal-containing solid waste to achieve the wet treatment.

3. The process according to claim 2, characterized in that, In step 3), adjust the pH to alkaline to achieve the fractional precipitation treatment; and / or adjust the pH with sodium base; and / or the second solid is a metal precipitate; and / or In step 4), the third solid is a pressure-filtered metal precipitate; and / or The fifth treatment liquid and the sixth treatment liquid are independently sodium sulfate solutions; and / or In step 7), the fourth solid is sodium sulfate; and / or the concentration of sodium sulfate in the sixth treatment liquid is less than 50 g / L.

4. The process according to claim 3, characterized in that, The sodium base is sodium hydroxide and / or sodium carbonate; and / or the metal precipitate is a metal hydroxide and / or a metal carbonate.

5. The process according to claim 3 or 4, characterized in that, In step 7), when the concentration of sodium sulfate in the fifth treatment liquid is less than 200 g / L, first concentrate the fifth treatment liquid to a sodium sulfate concentration of not less than 200 g / L, and then perform the condensation.

6. The process according to any one of claims 2 to 5, characterized in that The percentage of the mass of the metal-containing solid waste in the volume of the sulfuric acid and the percentage of the mass of the metal-containing solid waste in the volume of the leaching solution of Thiobacillus bacteria are independently 10% to 40%.

7. The process according to any one of claims 2 to 6, characterized in that, The sulfuric acid is an aqueous sulfuric acid solution; and / or In the leachate of Thiobacillus bacteria, the species density of Thiobacillus bacteria is 5×10 9 to 8×10 9 cells / mL.

8. The process according to claim 7, characterized in that, The pH of the aqueous sulfuric acid solution is 0.5 to 0.6; and / or the Thiobacillus bacteria include Acidithiobacillus thiooxidans and / or Acidithiobacillus caldus.

9. The process according to any one of claims 2 to 8, characterized in that, The treatment duration of the metal sulfuric acid leaching is not less than 24 h; and / or The treatment duration of the metal microbial leaching is 96 to 120 h.

10. The process according to claim 5, characterized in that, The temperature of the condensation is 0 to 5 °C; and / or The pressure of the concentration is 0.3 to 0.9 MPa.

11. Use of the process according to any one of claims 1 to 10 in the waste-free resource treatment of metal-containing solid waste.

12. The application according to claim 11, wherein The metal-containing solid waste includes smelting tailings, waste batteries, urban sludge and waste catalysts.

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