A method for preparing ceramsite by using hazardous waste zinc-nickel sludge and kyanite flotation tailings and a product thereof

Abstract

The application discloses a method for preparing ceramsite by using hazardous waste zinc-nickel-containing sludge and kyanite flotation tailings and a product thereof, and the method comprises the following steps: uniformly mixing fine-grained zinc-nickel-containing sludge, kyanite flotation tailings and palygorskite ore powder, mixing and stirring the mixture with water after high-speed grinding, and performing low-temperature plasma irradiation treatment; after the reaction is completed, the mixture is granulated and dried to obtain green balls; sintering is performed under an air atmosphere, and the ceramsite is obtained after cooling. The method combining high-speed grinding, low-temperature plasma irradiation and sintering is adopted, the hazardous waste zinc-nickel-containing sludge and the general solid waste kyanite flotation tailings are simultaneously recycled and harmlessly disposed, the obtained ceramsite has no hazardous characteristics and has high strength. The application not only eliminates the environmental risks of the hazardous waste heavy metal sludge and the general solid waste kyanite flotation tailings, but also converts the hazardous waste heavy metal sludge and the general solid waste kyanite flotation tailings into usable building materials, and has double benefits of environment and economy.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing ceramsite by using hazardous waste zinc-nickel-containing sludge and kyanite flotation tailings and a product thereof, and belongs to the field of harmless and resourceful disposal of hazardous waste. BACKGROUND

[0002] Zinc-nickel-containing sludge is a kind of hazardous waste with strong toxicity generated in the production process of surface treatment enterprises. At present, the harmless disposal process of zinc-nickel-containing sludge mainly includes chemical stabilization, cement kiln co-disposal and high-temperature sintering. The zinc-nickel-containing sludge stabilized by chemical method still needs to be safely landfilled, but the landfill site is limited and cannot continuously receive it. In order to ensure the quality of cement, the characteristics and amount of zinc-nickel-containing sludge entering the kiln are strictly required in cement kiln co-disposal. The high-temperature sintering method has high energy consumption, and also easily leads to the volatilization of part of zinc into flue gas, which increases the difficulty of flue gas treatment and thus increases the treatment cost.

[0003] Kyanite flotation tailings are tailings generated after flotation of medium-grade kyanite, which belong to general industrial solid waste. At present, due to its fine particle size and high content of gangue minerals, a large amount of kyanite flotation tailings are stored in tailings ponds. Due to the complex phase composition of impurities in kyanite flotation tailings, it is difficult to separate and purify, so its resource utilization is limited. On the one hand, the storage of tailings will occupy a large amount of land, and on the other hand, due to the adsorption of certain flotation reagents such as sodium sulfonate and amine on the surface of the tailings, it will cause water pollution.

[0004] Therefore, there is an urgent need for a simple and efficient method for resourceful disposal of hazardous waste zinc-nickel-containing sludge and kyanite flotation tailings. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a simple and efficient method for resourceful utilization of hazardous waste zinc-nickel-containing sludge and kyanite flotation tailings to prepare ceramsite.

[0006] Technical scheme: In order to solve the above technical problem, the present application provides a method for preparing ceramsite by using hazardous waste zinc-nickel-containing sludge and kyanite flotation tailings, which comprises the following steps:

[0007] (1) uniformly mixing fine particle zinc-nickel-containing sludge, kyanite flotation tailings and palygorskite powder, grinding to obtain a grinding product;

[0008] (2) adding water to the grinding material obtained in step (1) and stirring to prepare a slurry, and then performing low-temperature plasma irradiation treatment, after which granulation and drying are performed to obtain green balls;

[0009] (3) sintering the raw material balls obtained in step (2) under an air atmosphere, and obtaining the ceramsite after cooling.

[0010] In step (1), the mass ratio of the zinc-containing nickel sludge, the kyanite flotation tailings and the palygorskite ore powder is 30-42:31-50:20-27.

[0011] In step (1), the grinding rate is 420-580 revolutions per minute, and the grinding time is 8-22 hours.

[0012] In step (2), the low-temperature plasma irradiation voltage is 6-10 kV, and the irradiation time is 45-125 minutes.

[0013] In step (2), the solid phase mass percentage of the slurry is 42%-52%.

[0014] In step (2), the particle size of the granulated balls is 8-15 mm.

[0015] In step (2), the water content of the raw material balls is 4%-6%.

[0016] In step (3), the sintering temperature is 960-1060 DEG C, and the time is 18-28 minutes.

[0017] The application also provides a ceramsite prepared by the method, and the zinc leaching concentration of the ceramsite is at least 0.36±0.02 mg / L, and the Ni leaching concentration is at least 0.05±0.01 mg / L.

[0018] The principle of the application is as follows: the mechanical and chemical forces generated by high-speed ball milling convert the ordered crystal form with low chemical reactivity in the zinc-containing nickel sludge, the kyanite flotation tailings and the palygorskite into a disordered amorphous form with high chemical reactivity, continuously generating active components such as silicates, aluminosilicates and ferric aluminates. The grinding product is mixed with water to prepare a slurry, and the slurry is irradiated by low-temperature plasma. A large number of high-energy electrons, ions and free radicals will bombard the material at high speed, so that the silicon-oxygen tetrahedron, aluminum-oxygen octahedron and iron-oxygen tetrahedron network structure in the material components are broken under the action of high-energy particles, forming a large number of unsaturated bonds and defect sites. These unsaturated bonds and defect sites have high chemical activity and can rapidly react with the surrounding heavy metal ions to generate silicon-oxygen, aluminum-oxygen and silicon-aluminum-oxygen network polymers, which in turn wrap, stabilize or solidify a large amount of zinc components and nickel components, achieving the stabilization and solidification of zinc and nickel.

[0019] In the sintering process, the high-activity zinc component, nickel component, aluminum component, magnesium component, iron component, calcium component and silicon component in the raw material ball will quickly form zinc aluminum spinel, zinc iron spinel, nickel iron spinel and other phases, further realizing the structural fixation of zinc and nickel, realizing the strengthening and solidification of zinc and nickel, greatly reducing the volatilization of zinc and nickel, and also producing a large amount of aluminum silicate, mullite and other phases, enhancing the strength of the structure of the ceramsite. In addition, due to the synergistic effect of mechanochemistry and plasma irradiation, the solid phase reaction activity of the material is improved, the energy supply of the solid phase reaction of the material is reduced, and thus the sintering temperature and the calcination time of the material are reduced, realizing the significant reduction of the energy consumption of the ceramsite sintering process.

[0020] Advantages: Compared with the prior art, the present application has the following obvious advantages:

[0021] 1. Based on the chemical composition and characteristics of waste, the present application adopts the method of high-speed grinding-low-temperature plasma irradiation-sintering combination to realize the synergistic resource utilization and harmless disposal of hazardous waste zinc and nickel-containing sludge and general solid waste kyanite flotation tailings.

[0022] 2. By adjusting the ratio of raw materials, the synergistic effect of mechanochemistry and plasma irradiation is combined to improve the solid phase reaction activity of the material, reduce the energy supply of the solid phase reaction of the material, and thus reduce the sintering temperature and the calcination time of the material, greatly reduce the volatilization of zinc and nickel, and realize the significant reduction of the energy consumption of the ceramsite sintering process, which is beneficial to energy saving and emission reduction and low carbon emission.

[0023] 3. The ceramsite obtained by the present application has a minimum zinc leaching concentration of 0.36±0.02mg / L and a minimum Ni leaching concentration of 0.05±0.01mg / L, has no hazardous characteristics, and has high strength. The present application not only eliminates the environmental risk of hazardous waste heavy metal sludge and general solid waste kyanite flotation tailings, but also converts them into usable building materials, having double benefits of environment and economy. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The process flow chart of the present application. DETAILED DESCRIPTION

[0025] The technical solutions of the present application will be further described below in combination with the drawings.

[0026] The zinc-containing nickel sludge was obtained from Rongchang Metal Surface Treatment Co., Ltd. in Suzhou Industrial Park, and was a sludge generated from heavy metal wastewater treatment. The chemical composition of the zinc-containing nickel sludge was SiO2 2.69%, Al2O3 5.06%, Fe2O3 21.84%, MgO 1.70%, CaO 37.25%, Na2O 0.19%, K2O 0.23%, TiO2 0.33%, ZnO 16.53%, SO3 7.51%, NiO 1.17%, Cr2O3 0.30%, P2O5 2.49%, Cl 1.76%, F 0.53%, and loss on ignition 0.42%.

[0027] The kyanite flotation tailings were obtained from Kyanite Mine in Kaiyuan, Nanyang City, Henan Province, and were tailings generated after flotation and purification of kyanite with medium-grade kyanite. The chemical composition of the kyanite flotation tailings was SiO2 46.27%, Al2O3 43.08%, K2O 3.70%, Na2O 0.95%, and other components 6%.

[0028] The palygorskite was obtained from Changzhou Dingbang Mineral Products Technology Co., Ltd. The chemical composition of the palygorskite was SiO2 72.91%, Al2O3 14.28%, Fe2O3 1.01%, CaO 4.95%, Na2O 2.10%, K2O 2.04%, MgO 2.34%, SO3 0.05%, Cl 0.02%, P2O5 0.02%, TiO2 0.11%, BaO 0.09%, and MnO 0.08%.

[0029] Example 1

[0030] A total mass of 35 g of fine-grained zinc-containing nickel sludge, kyanite flotation tailings and palygorskite were mixed uniformly at a dry basis mass percentage of 30:50:20 to obtain a mixture, and the mixture was added to a vertical planetary ball mill for grinding at a speed of 580 revolutions per minute for 8 hours. The grinding product was mixed with water to prepare a slurry with a solid phase mass content of 42%, and the slurry was subjected to low-temperature plasma irradiation treatment at a low-temperature plasma irradiation voltage of 6 kV for 125 minutes. After the low-temperature plasma irradiation treatment, granulation was performed, and the granules with a particle size of 15 mm were dried in a vacuum drying oven after granulation to obtain green balls. The water content of the green balls was 4.0%. The green balls were placed in a high-temperature furnace for sintering at a sintering temperature of 1060°C for 18 minutes in an air atmosphere, and were naturally cooled after sintering to obtain ceramic A1.

[0031] The heavy metal leaching toxicity of the ceramsite A1 was tested by using the "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid Nitric Acid Method" (HJ / T 299-2007), and the zinc leaching concentration of the ceramsite A1 was 0.36±0.02 mg / L, and the Ni leaching concentration was 0.05±0.01 mg / L, which was far lower than the concentration limit value of the zinc and nickel leaching concentration limit value (100 mg / L and 5 mg / L) in the "Hazardous Waste Identification Standard Leaching Toxicity Identification" (GB 5085.3-2007) toxicity identification standard concentration limit value; the cylinder pressure strength and the bulk density of the ceramsite A1 were tested according to the "Lightweight Aggregate and Test Methods for Lightweight Aggregate Part 2: Test Methods for Lightweight Aggregate" (GB / T 17431.2-2010), and the results showed that the cylinder pressure strength of the ceramsite A1 was 9.40 Mpa, and the bulk density was 885 kg / m 3 , which met the requirements specified in the "Lightweight Aggregate and Test Methods Part 1: Lightweight Aggregate" (GB / T 17431.1-2010).

[0032] Example 2

[0033] The fine particle zinc and nickel-containing sludge, the kyanite flotation tailings and the palygorskite powder with a total mass of 35 g were mixed uniformly in a dry basis mass percentage of 42:31:27 to obtain a mixture, and the mixture was added to a vertical planetary ball mill for grinding for 18 hours at a speed of 450 revolutions / minute. The grinding product was mixed with water to prepare a slurry with a solid phase mass content of 50%, and the slurry was subjected to low-temperature plasma irradiation treatment at a low-temperature plasma irradiation voltage of 8 kV for 65 minutes. After the low-temperature plasma irradiation treatment was completed, granulation was performed, and the granules with a particle size of 10 mm were screened and dried in a vacuum drying box to obtain green balls. The water content of the green balls was 5.0%. The green balls were placed in a high-temperature furnace for sintering at a sintering temperature of 1000°C for 22 minutes in an air atmosphere, and were naturally cooled after sintering to obtain the ceramsite A2.

[0034] The heavy metal leaching toxicity of the ceramsite A2 was tested by using the "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid Nitric Acid Method" (HJ / T 299-2007), and the zinc leaching concentration of the ceramsite A2 was 0.87±0.01 mg / L, and the Ni leaching concentration was 0.16±0.01 mg / L, which was far lower than the concentration limit value of the zinc and nickel leaching concentration limit value (100 mg / L and 5 mg / L) in the "Hazardous Waste Identification Standard Leaching Toxicity Identification" (GB 5085.3-2007); the cylinder pressure strength and the bulk density of the ceramsite A2 were tested according to the "Lightweight Aggregate and Test Methods for Lightweight Aggregate Part 2: Test Methods for Lightweight Aggregate" (GB / T 17431.2-2010), and the results showed that the cylinder pressure strength of the ceramsite A2 was 7.23 Mpa, and the bulk density was 812 kg / m 3, which meets the requirements of the Light-weight Aggregate and Its Test Methods Part 1: Light-weight Aggregate (GB / T 17431.1-2010).

[0035] Example 3

[0036] The fine particle zinc-containing nickel sludge, kyanite flotation tailings and palygorskite powder with a total mass of 35 g were mixed uniformly in a dry basis mass percentage of 35:40:25 to obtain a mixture. The mixture was obtained and added to a vertical planetary ball mill for grinding for 22 hours at a rotation speed of 420 revolutions / minute. The grinding product was mixed with water to prepare a slurry with a solid phase mass content of 52%, and the slurry was subjected to low-temperature plasma irradiation treatment at a low-temperature plasma irradiation voltage of 10 kV for an irradiation time of 45 minutes. After the low-temperature plasma irradiation treatment was completed, granulation was performed, and after the granulation was completed, the pellets with a particle size of 8 mm were dried in a vacuum drying box to obtain green pellets. The water content of the green pellets was 6.0%. The green pellets were placed in a high-temperature furnace for sintering at a sintering temperature of 960°C for a sintering time of 28 minutes in an air atmosphere, and after the sintering was completed, natural cooling was performed to obtain ceramic aggregate A3.

[0037] The heavy metal leaching toxicity of the ceramic aggregate A3 was tested by using the Solid Wastes Leaching Toxicity Test Method-Sulfuric Acid and Nitric Acid Method (HJ / T 299-2007), and it was measured that the zinc leaching concentration of the ceramic aggregate A3 was 0.66±0.02 mg / L, and the Ni leaching concentration was 0.10±0.01 mg / L, which was far lower than the zinc and nickel leaching concentration limits (100 mg / L and 5 mg / L) in the Hazardous Waste Identification Standard-Leaching Toxicity Identification (GB 5085.3-2007). The cylinder compressive strength and the bulk density of the ceramic aggregate A3 were tested according to the Light-weight Aggregate and Its Test Methods Part 2: Light-weight Aggregate Test Methods (GB / T 17431.2-2010), and the results were that the cylinder compressive strength of the ceramic aggregate A3 was 7.41 Mpa, and the bulk density was 833 kg / m 3 , which meets the requirements of the Light-weight Aggregate and Its Test Methods Part 1: Light-weight Aggregate (GB / T 17431.1-2010).

[0038] Comparative Example 1

[0039] The fine particle zinc-containing nickel sludge, kyanite flotation tailings and palygorskite powder with a total mass of 35 g were mixed uniformly in a mass percentage of 30:50:20 on a dry basis to obtain a mixture. The mixture was mixed with water to prepare a slurry with a solid phase mass content of 42%, and the slurry was subjected to low-temperature plasma irradiation treatment at a low-temperature plasma irradiation voltage of 6 kV and an irradiation time of 125 minutes. After the low-temperature plasma irradiation treatment was completed, granulation was performed, and after the granulation was completed, the spherical particles with a particle size of 15 mm were screened and dried in a vacuum drying box to obtain green balls. The water content of the green balls was 4.0%. The green balls were placed in a high-temperature furnace for sintering at a sintering temperature of 1060°C for 18 minutes in an air atmosphere, and after sintering was completed, natural cooling was performed to obtain ceramic B1.

[0040] The heavy metal leaching toxicity of ceramic B1 was tested by using “Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid Nitric Acid Method” (HJ / T299-2007), and the zinc leaching concentration of ceramic B1 was 198.23±0.06 mg / L, and the Ni leaching concentration was 12.35±0.04 mg / L, which was higher than the zinc and nickel leaching concentration limit value (100 mg / L and 5 mg / L) in “Hazardous Waste Identification Standard Leaching Toxicity Identification”.

[0041] Comparative Example 2

[0042] The fine particle zinc-containing nickel sludge, kyanite flotation tailings and palygorskite powder with a total mass of 35 g were mixed uniformly in a mass percentage of 30:50:20 on a dry basis to obtain a mixture, and the mixture was added to a vertical planetary ball mill for grinding for 8 hours at a speed of 580 revolutions / minute. The grinding product was mixed with water to prepare a slurry with a solid phase mass content of 42% and subjected to granulation, and after the granulation was completed, the spherical particles with a particle size of 15 mm were screened and dried in a vacuum drying box to obtain green balls. The water content of the green balls was 4.0%. The green balls were placed in a high-temperature furnace for sintering at a sintering temperature of 1060°C for 18 minutes in an air atmosphere, and after sintering was completed, natural cooling was performed to obtain ceramic B2.

[0043] The heavy metal leaching toxicity of ceramic B2 was tested by using “Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid Nitric Acid Method” (HJ / T299-2007), and the zinc leaching concentration of ceramic B2 was 76.35±0.04 mg / L, which was lower than the zinc leaching concentration limit value (100 mg / L) in “Hazardous Waste Identification Standard Leaching Toxicity Identification”; the Ni leaching concentration was 9.67±0.03 mg / L, which was higher than the nickel leaching concentration limit value (5 mg / L) in “Hazardous Waste Identification Standard Leaching Toxicity Identification”.

[0044] Comparative Example 3

[0045] The method of Example 1 was used to prepare ceramsite under different raw material ratios, grinding conditions, low-temperature plasma action conditions and sintering conditions, and the heavy metal leaching toxicity of the ceramsite was tested by using the "Solid Waste Leaching Toxicity Leaching Method-Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007), and the results are shown in Table 1.

[0046] Table 1

[0047]

[0048] The results in Table 1 show that the zinc leaching concentrations of the No. 1, No. 3, No. 4, No. 7 and No. 8 ceramsite samples in Comparative Example 3 are higher than the environmental threshold value, and the nickel leaching concentrations of all the ceramsite samples are higher than the environmental threshold value, which are still dangerous.

Claims

1. A method for preparing ceramsite by utilizing hazardous waste zinc-nickel sludge and kyanite flotation tailings, characterized in that: The following steps are involved: (1) uniformly mixing the zinc-nickel sludge, kyanite flotation tailings and palygorskite ore powder, and grinding them to obtain a grinding product; The dry mass ratio of the zinc-nickel sludge, kyanite flotation tailings, and palygorskite powder is 30-42:31-50:20-27; the grinding speed is 420-580 rpm, and the grinding time is 8-22 hours; (2) adding water to the ground product obtained in step (1) and stirring to prepare a slurry, and then subjecting it to low-temperature plasma irradiation, granulating and drying it after the end to obtain raw material balls; the solid mass percentage of the slurry is 42% to 52%; the voltage of the low-temperature plasma irradiation is 6 to 10 kV, and the irradiation time is 45 to 125 minutes; (3) Sintering the raw material balls obtained in step (2) in an air atmosphere and obtaining ceramsite after cooling; the sintering temperature is 960-1060° C. and the sintering time is 18-28 minutes.

2. The method according to claim 1, characterized in that The particle size of the pellets after granulation in step (2) is 8-15 mm.

3. The method according to claim 1, characterized in that The moisture content of the raw material balls in step (2) is 4% to 6%.

4. A ceramsite prepared by the method according to any one of claims 1 to 3.

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