Method for preparing building materials by using three solidification technologies for sludge with excessive heavy metals

Abstract

This invention discloses a method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology. The method includes material selection, preparation of modified sludge, high-temperature treatment, vibration mixing, preparation of modified slag, raw material mixing, and molding. The raw materials include sludge, iron ore slag, lightweight aggregate, fly ash, sludge solidification agent, cement, and sand. The solidification agent passivates the heavy metals in the sludge, achieving a first layer of sealing. Then, a high-frequency oscillator allows dust, along with the heavy metals within it, to permeate into the pores of the lightweight aggregate for a second layer of sealing. Finally, the treated lightweight aggregate is mixed with cement and sand for a third layer of sealing, thus achieving triple solidification of heavy metals. This reduces the harmful effects of heavy metals, rationally reusing sludge and industrial tailings, saving space occupied by sludge and industrial tailings, mitigating the environmental impact of sludge and industrial tailings, and conserving significant resources.

Description

Technical Field

[0001] This invention belongs to the field of building material preparation technology, specifically relating to a method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology. Background Technology

[0002] Sludge is a byproduct of wastewater treatment, an extremely complex heterogeneous body composed of organic debris, bacterial cells, inorganic particles, and colloidal sludge. The main characteristics of sludge are high water content (up to 99% or more), high organic matter content, easy decomposition and foul odor, fine particles, low specific gravity, and a colloidal liquid state. Furthermore, most industrial sludge exceeds heavy metal standards, causing serious environmental pollution. Mineral resources are vital natural resources for human survival. While their development and utilization have provided a significant impetus for social progress, they have also generated large amounts of waste rock and tailings, which not only occupy arable land and pollute the environment but also impose a huge burden on the nation and enterprises. Tailings, generally considered waste, often need to be transported elsewhere, occupying considerable space and being difficult to dispose of.

[0003] With the development of the times, the country has gradually attached great importance to the reuse of waste such as sludge and tailings. How to treat and utilize large amounts of sludge and tailings is a problem that must be taken seriously. Therefore, the main research direction is to effectively and efficiently reduce the amount of sludge and tailings, make them harmless, and then turn them into resources. Comprehensive utilization of sludge and tailings under the premise of harmlessness is the best way to treat and dispose of sludge and tailings. It can not only obtain good environmental benefits, but also have certain social and economic benefits. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology, in order to solve the problems mentioned in the background art, such as low utilization rate of sludge and industrial tailings, large land area occupation, and environmental pollution.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing building materials from sludge with excessive heavy metal content using a triple solidification technology, the preparation method comprising the following steps:

[0006] S1: Material selection: 35-40 parts sludge, 5-10 parts iron ore slag, 70-80 parts lightweight aggregate, 5-20 parts fly ash, 2.8-3.2 parts sludge solidification agent; 5-20 parts cement, 25-100 parts sand.

[0007] S2: Preparation of modified sludge: First, take the appropriate amount of sludge and put it into a mixer. Add the appropriate amount of sludge solidifying agent to the mixer. After the mixer is fully mixed, the heavy metals in the sludge are passivated. The mixed sludge is then subjected to high-efficiency sludge dewatering technology to maintain the relative dispersion between sludge particles, thus obtaining modified sludge.

[0008] S3: High-temperature treatment: The modified sludge after S2 dehydration is placed in a high-temperature furnace for baking. Under the action of high temperature, the water in the sludge is evaporated. Then the baked sludge is stirred to disperse the sludge, leaving the heavy metals in the dust after high-temperature treatment. The dust is collected by negative pressure.

[0009] S4: Vibration Mixing: The dust treated at high temperature in S3 and the corresponding amount of lightweight aggregate are placed into a high-frequency vibrator for high-frequency vibration mixing. Utilizing the porosity of the lightweight aggregate, combined with the effect of high-frequency vibration, the dust, along with the heavy metals inside it, penetrates into the pores of the lightweight aggregate, thus performing secondary sealing of the heavy metals.

[0010] S5: Preparation of modified slag: After crushing the iron ore slag, the iron ore slag is screened using a screening machine, and then magnetic separation is performed on the iron ore slag to remove useless and harmful metals, thus obtaining modified slag.

[0011] S6: Raw material mixing: The dust and lightweight aggregate mixed by vibration in S4, the modified slag prepared in S5, and the remaining raw materials are put into a mixer for thorough mixing and stirring, and heavy metals are sealed three times.

[0012] S7: Molding: The raw materials that have been fully mixed in S6 are placed into a high-pressure molding machine and pressed into shape to obtain new building materials.

[0013] Preferably, in step S2, sludge solidification agent is added to the mixer, and the mixing time is 10-20 minutes, with a mixing speed of 500-1000 r / min.

[0014] Preferably, in step S3, the modified sludge is placed in a high-temperature furnace for baking at a temperature of 100-120°C for 30-50 minutes.

[0015] Preferably, in step S4, the dust and lightweight aggregate are placed in a high-frequency oscillator and oscillated for 20-30 minutes, allowing the dust, along with its internal heavy metals, to penetrate into the pores of the lightweight aggregate.

[0016] Preferably, in step S5, the iron ore slag is screened using a screening machine to obtain iron ore slag with a diameter of 0.5-0.8 mm.

[0017] Preferably, in step S6, the time for fully mixing the material in the mixer is 40-60 minutes, and the mixer speed is 600-1000 r / min.

[0018] Preferably, in step S7, the molding pressure of the high-pressure molding machine is 0.4-0.6 MPa.

[0019] Preferably, the sludge contains one or more of the heavy metals Cd, Pb, Ni, Cr, Mn, Cu, Zn, and Fe.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. The first layer of sealing is achieved by passivating the heavy metals in the sludge with a solidifying agent. Then, the dust and the heavy metals inside it are allowed to penetrate into the pores of the lightweight aggregate through the action of a high-frequency oscillator for secondary sealing. Finally, the treated lightweight aggregate is mixed with cement, sand, etc., for a third sealing and solidification process, thereby achieving triple solidification of heavy metals and reducing their harmful effects.

[0022] 2. Through the preparation method of the present invention, sludge and industrial tailings are reused in a reasonable way, saving the space occupied by sludge and industrial tailings, reducing the environmental impact of sludge, industrial tailings and other wastes, and saving a lot of resources through the reuse of sludge and industrial tailings and other wastes. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1:

[0025] This invention provides a technical solution: a method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology, the preparation method comprising the following steps:

[0026] S1: Material selection: 35 parts sludge, 5 parts iron ore slag, 70 parts lightweight aggregate, 5 parts fly ash, 2.8 parts sludge solidification agent; 5 parts cement, 25 parts sand.

[0027] S2: Preparation of modified sludge: First, take the appropriate amount of sludge and put it into a mixer. Add the appropriate amount of sludge solidifying agent to the mixer and mix it thoroughly. The mixing time is 10 minutes and the stirring speed is 500 r / min to passivate the heavy metals in the sludge. Then, pass the mixed sludge through a high-efficiency sludge dewatering technology to maintain the relative dispersion between sludge particles, thus obtaining modified sludge.

[0028] S3: High-temperature treatment: The modified sludge after S2 dehydration is placed in a high-temperature furnace for baking at 100°C for 30 minutes. Under high temperature, the water in the sludge is evaporated. The baked sludge is then stirred to disperse it, leaving heavy metals in the dust after high-temperature treatment. The dust is then collected by negative pressure.

[0029] S4: Vibration Mixing: The dust treated at high temperature in S3 and the corresponding amount of lightweight aggregate are placed into a high-frequency vibrator for high-frequency vibration mixing. The vibration time is 20 minutes. By utilizing the porosity of the lightweight aggregate and the effect of high-frequency vibration, the dust, along with the heavy metals inside it, penetrates into the pores of the lightweight aggregate, thus performing secondary sealing of the heavy metals.

[0030] S5: Preparation of modified slag: After crushing the iron ore slag, the iron ore slag is screened using a screening machine, and then magnetic separation is performed on the iron ore slag to remove useless and harmful metals. The screened iron ore slag with a diameter of 0.5mm is obtained, thus obtaining modified slag.

[0031] S6: Raw material mixing: The dust and lightweight aggregate mixed by vibration in S4, the modified slag prepared in S5, and the remaining raw materials are put into a mixer for thorough mixing. The mixing time is 40 minutes and the mixer speed is 600 r / min. Heavy metals are sealed three times.

[0032] S7: Molding: The raw materials that have been fully mixed in S6 are placed into a high-pressure molding machine and pressed into shape. The molding pressure of the high-pressure molding machine is 0.4MPa, thereby obtaining a new type of building material.

[0033] Example 2:

[0034] This invention provides a technical solution: a method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology, the preparation method comprising the following steps:

[0035] S1: Material selection: 36 parts sludge, 5 parts iron ore slag, 73 parts lightweight aggregate, 5 parts fly ash, 2.8 parts sludge solidification agent; 5 parts cement, 30 parts sand.

[0036] S2: Preparation of modified sludge: First, take the appropriate amount of sludge and put it into a mixer. Add the appropriate amount of sludge solidifying agent to the mixer and mix it thoroughly. The mixing time is 15 minutes and the stirring speed is 500 r / min to passivate the heavy metals in the sludge. Then, pass the mixed sludge through a high-efficiency sludge dewatering technology to maintain the relative dispersion between sludge particles, thus obtaining modified sludge.

[0037] S3: High-temperature treatment: The modified sludge after S2 dehydration is placed in a high-temperature furnace for baking at 100°C for 35 minutes. Under high temperature, the water in the sludge is evaporated. The baked sludge is then stirred to disperse it, leaving heavy metals in the dust after high-temperature treatment. The dust is then collected by negative pressure.

[0038] S4: Vibration Mixing: The dust treated at high temperature in S3 and the corresponding amount of lightweight aggregate are placed into a high-frequency vibrator for high-frequency vibration mixing. The vibration time is 20 minutes. By utilizing the porosity of the lightweight aggregate and the effect of high-frequency vibration, the dust, along with the heavy metals inside it, penetrates into the pores of the lightweight aggregate, thus performing secondary sealing of the heavy metals.

[0039] S5: Preparation of modified slag: After crushing the iron ore slag, the iron ore slag is screened using a screening machine, and then magnetic separation is performed on the iron ore slag to remove useless and harmful metals. The screened iron ore slag with a diameter of 0.5mm is obtained, thus obtaining modified slag.

[0040] S6: Raw material mixing: The dust and lightweight aggregate mixed by vibration in S4, the modified slag prepared in S5, and the remaining raw materials are put into a mixer for thorough mixing. The mixing time is 40 minutes and the mixer speed is 600 r / min. Heavy metals are sealed three times.

[0041] S7: Molding: The raw materials that have been fully mixed in S6 are placed into a high-pressure molding machine and pressed into shape. The molding pressure of the high-pressure molding machine is 0.4MPa, thereby obtaining a new type of building material.

[0042] Example 3:

[0043] This invention provides a technical solution: a method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology, the preparation method comprising the following steps:

[0044] S1: Material selection: 36 parts sludge, 6 parts iron ore slag, 73 parts lightweight aggregate, 10 parts fly ash, 2.9 parts sludge solidification agent; 10 parts cement, 40 parts sand.

[0045] S2: Preparation of modified sludge: First, take the appropriate amount of sludge and put it into a mixer. Add the appropriate amount of sludge solidifying agent to the mixer and mix it thoroughly. The mixing time is 15 minutes and the stirring speed is 600 r / min to passivate the heavy metals in the sludge. Then, pass the mixed sludge through a high-efficiency sludge dewatering technology to maintain the relative dispersion between sludge particles, thus obtaining modified sludge.

[0046] S3: High-temperature treatment: The modified sludge after S2 dehydration is placed in a high-temperature furnace for baking at 100°C for 40 minutes. Under high temperature, the water in the sludge is evaporated. The baked sludge is then stirred to disperse it, leaving heavy metals in the dust after high-temperature treatment. The dust is then collected by negative pressure.

[0047] S4: Vibration Mixing: The dust treated at high temperature in S3 and the corresponding amount of lightweight aggregate are placed into a high-frequency vibrator for high-frequency vibration mixing. The vibration time is 20 minutes. By utilizing the porosity of the lightweight aggregate and the effect of high-frequency vibration, the dust, along with the heavy metals inside it, penetrates into the pores of the lightweight aggregate, thus performing secondary sealing of the heavy metals.

[0048] S5: Preparation of modified slag: After crushing the iron ore slag, the iron ore slag is screened using a screening machine, and then magnetic separation is performed on the iron ore slag to remove useless and harmful metals. The screened iron ore slag with a diameter of 0.6mm is obtained, thus obtaining modified slag.

[0049] S6: Raw material mixing: The dust and lightweight aggregate mixed by vibration in S4, the modified slag prepared in S5, and the remaining raw materials are put into a mixer for thorough mixing. The mixing time is 40 minutes and the mixer speed is 700 r / min. Heavy metals are sealed three times.

[0050] S7: Molding: The raw materials that have been fully mixed in S6 are placed into a high-pressure molding machine and pressed into shape. The molding pressure of the high-pressure molding machine is 0.4MPa, thereby obtaining a new type of building material.

[0051] Example 4:

[0052] This invention provides a technical solution: a method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology, the preparation method comprising the following steps:

[0053] S1: Material selection: 37 parts sludge, 7 parts iron ore slag, 75 parts lightweight aggregate, 12 parts fly ash, 3 parts sludge solidification agent; 15 parts cement, 50 parts sand.

[0054] S2: Preparation of modified sludge: First, take the appropriate amount of sludge and put it into a mixer. Add the appropriate amount of sludge solidifying agent to the mixer and mix it thoroughly. The mixing time is 15 minutes and the stirring speed is 700 r / min to passivate the heavy metals in the sludge. Then, pass the mixed sludge through a high-efficiency sludge dewatering technology to maintain the relative dispersion between sludge particles, thus obtaining modified sludge.

[0055] S3: High-temperature treatment: The modified sludge after S2 dehydration is placed in a high-temperature furnace for baking at 110°C for 40 minutes. Under high temperature, the water in the sludge is evaporated. The baked sludge is then stirred to disperse it, leaving the heavy metals in the dust after high-temperature treatment. The dust is then collected by negative pressure.

[0056] S4: Vibration Mixing: The dust treated by S3 at high temperature and the corresponding amount of lightweight aggregate are put into a high-frequency vibrator for high-frequency vibration mixing. The vibration time is 25 minutes. By utilizing the porosity of the lightweight aggregate and the effect of high-frequency vibration, the dust and its internal heavy metals are allowed to penetrate into the pores of the lightweight aggregate, thus performing secondary sealing of the heavy metals.

[0057] S5: Preparation of modified slag: After crushing the iron ore slag, the iron ore slag is screened using a screening machine, and then magnetic separation is performed on the iron ore slag to remove useless and harmful metals. The screened iron ore slag with a diameter of 0.7mm is obtained, thus obtaining modified slag.

[0058] S6: Raw material mixing: The dust and lightweight aggregate mixed by vibration in S4, the modified slag prepared in S5, and the remaining raw materials are put into a mixer for thorough mixing. The mixing time is 40 minutes and the mixer speed is 800 r / min. Heavy metals are sealed three times.

[0059] S7: Molding: The raw materials that have been fully mixed in S6 are placed into a high-pressure molding machine and pressed into shape. The molding pressure of the high-pressure molding machine is 0.5MPa, thereby obtaining a new type of building material.

[0060] Example 5:

[0061] This invention provides a technical solution: a method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology, the preparation method comprising the following steps:

[0062] S1: Material selection: 38 parts sludge, 8 parts iron ore slag, 75 parts lightweight aggregate, 15 parts fly ash, 3 parts sludge solidification agent; 15 parts cement, 60 parts sand.

[0063] S2: Preparation of modified sludge: First, take the appropriate amount of sludge and put it into a mixer. Add the appropriate amount of sludge solidifying agent to the mixer and mix it thoroughly. The mixing time is 15 minutes and the stirring speed is 800 r / min to passivate the heavy metals in the sludge. Then, pass the mixed sludge through a high-efficiency sludge dewatering technology to maintain the relative dispersion between sludge particles, thus obtaining modified sludge.

[0064] S3: High-temperature treatment: The modified sludge after S2 dehydration is placed in a high-temperature furnace for baking at 110°C for 45 minutes. Under high temperature, the water in the sludge is evaporated. The baked sludge is then stirred to disperse it, leaving the heavy metals in the dust after high-temperature treatment. The dust is then collected by negative pressure.

[0065] S4: Vibration Mixing: The dust treated by S3 at high temperature and the corresponding amount of lightweight aggregate are put into a high-frequency vibrator for high-frequency vibration mixing. The vibration time is 25 minutes. By utilizing the porosity of the lightweight aggregate and the effect of high-frequency vibration, the dust and its internal heavy metals are allowed to penetrate into the pores of the lightweight aggregate, thus performing secondary sealing of the heavy metals.

[0066] S5: Preparation of modified slag: After crushing the iron ore slag, the iron ore slag is screened using a screening machine, and then magnetic separation is performed on the iron ore slag to remove useless and harmful metals. The screened iron ore slag with a diameter of 0.7mm is obtained, thus obtaining modified slag.

[0067] S6: Raw material mixing: The dust and lightweight aggregate mixed by vibration in S4, the modified slag prepared in S5, and the remaining raw materials are put into a mixer for thorough mixing. The mixing time is 40 minutes and the mixer speed is 900 r / min. Heavy metals are sealed three times.

[0068] S7: Molding: The raw materials that have been fully mixed in S6 are placed into a high-pressure molding machine and pressed into shape. The molding pressure of the high-pressure molding machine is 0.5MPa, thereby obtaining a new type of building material.

[0069] Example 6:

[0070] This invention provides a technical solution: a method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology, the preparation method comprising the following steps:

[0071] S1: Material selection: 39 parts sludge, 9 parts iron ore slag, 80 parts lightweight aggregate, 18 parts fly ash, 3.1 parts sludge solidification agent; 18 parts cement, 80 parts sand.

[0072] S2: Preparation of modified sludge: First, take the appropriate amount of sludge and put it into a mixer. Add the appropriate amount of sludge solidifying agent to the mixer and mix it thoroughly. The mixing time is 17 minutes and the stirring speed is 900 r / min to passivate the heavy metals in the sludge. Then, pass the mixed sludge through a high-efficiency sludge dewatering technology to maintain the relative dispersion between sludge particles, thus obtaining modified sludge.

[0073] S3: High-temperature treatment: The modified sludge after S2 dehydration is placed in a high-temperature furnace for baking at 120°C for 45 minutes. Under high temperature, the water in the sludge is evaporated. The baked sludge is then stirred to disperse it, leaving the heavy metals in the dust after high-temperature treatment. The dust is then collected by negative pressure.

[0074] S4: Vibration Mixing: The dust treated by S3 at high temperature and the corresponding amount of lightweight aggregate are put into a high-frequency vibrator for high-frequency vibration mixing. The vibration time is 25 minutes. By utilizing the porosity of the lightweight aggregate and the effect of high-frequency vibration, the dust and its internal heavy metals are allowed to penetrate into the pores of the lightweight aggregate, thus performing secondary sealing of the heavy metals.

[0075] S5: Preparation of modified slag: After crushing the iron ore slag, the iron ore slag is screened using a screening machine, and then magnetic separation is performed on the iron ore slag to remove useless and harmful metals. The screened iron ore slag with a diameter of 0.8mm is obtained, thus obtaining modified slag.

[0076] S6: Raw material mixing: The dust and lightweight aggregate mixed by vibration in S4, the modified slag prepared in S5, and the remaining raw materials are put into a mixer for thorough mixing. The mixing time is 40 minutes and the mixer speed is 900 r / min. Heavy metals are sealed three times.

[0077] S7: Molding: The raw materials that have been fully mixed in S6 are placed into a high-pressure molding machine and pressed into shape. The molding pressure of the high-pressure molding machine is 0.6MPa, thereby obtaining a new type of building material.

[0078] Embodiment seven:

[0079] This invention provides a technical solution: a method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology, the preparation method comprising the following steps:

[0080] S1: Material selection: 40 parts sludge, 10 parts iron ore slag, 80 parts lightweight aggregate, 20 parts fly ash, 3.2 parts sludge solidification agent; 20 parts cement, 100 parts sand.

[0081] S2: Preparation of modified sludge: First, take the appropriate amount of sludge and put it into a mixer. Add the appropriate amount of sludge solidifying agent to the mixer and mix it thoroughly. The mixing time is 20 minutes and the stirring speed is 1000 r / min to passivate the heavy metals in the sludge. Then, pass the mixed sludge through a high-efficiency sludge dewatering technology to maintain the relative dispersion between sludge particles, thus obtaining modified sludge.

[0082] S3: High-temperature treatment: The modified sludge after S2 dehydration is placed in a high-temperature furnace for baking at 120°C for 50 minutes. Under high temperature, the water in the sludge is evaporated. The baked sludge is then stirred to disperse it, leaving heavy metals in the dust after high-temperature treatment. The dust is then collected by negative pressure.

[0083] S4: Vibration Mixing: The dust treated at high temperature in S3 and the corresponding amount of lightweight aggregate are placed into a high-frequency vibrator for high-frequency vibration mixing for 30 minutes. By utilizing the porosity of the lightweight aggregate and the effect of high-frequency vibration, the dust, along with the heavy metals inside it, penetrates into the pores of the lightweight aggregate, thus performing secondary sealing of the heavy metals.

[0084] S5: Preparation of modified slag: After crushing the iron ore slag, the iron ore slag is screened using a screening machine, and then magnetic separation is performed on the iron ore slag to remove useless and harmful metals. The screened iron ore slag with a diameter of 0.8mm is obtained, thus obtaining modified slag.

[0085] S6: Raw material mixing: The dust and lightweight aggregate mixed by vibration in S4, the modified slag prepared in S5, and the remaining raw materials are put into a mixer for thorough mixing. The mixing time is 40 minutes and the mixer speed is 1000 r / min. Heavy metals are sealed three times.

[0086] S7: Molding: The raw materials that have been fully mixed in S6 are placed into a high-pressure molding machine and pressed into shape. The molding pressure of the high-pressure molding machine is 0.6MPa, thereby obtaining a new type of building material.

[0087] It is worth noting that the sludge and iron ore slag in Examples 1-7 above have the same composition, that is, the sludge contains heavy metals Cd, Pb, Ni, Cr, Mn, Cu, and Zn; wherein, the sludge per unit volume contains Cu 8849.84 mg / L; Zn 1513.23 mg / L; Ni 1843.39 mg / L; Cd 268.54 mg / L; Cr 32760.28 mg / L; and Pb 642.78 mg / L.

[0088] The compressive strength and thermal conductivity of the building materials prepared in Examples 1-7 above were tested respectively, and the test results are shown in the table below:

[0089]

[0090] It is evident that the building material prepared by this invention has good compressive strength and thermal insulation properties.

[0091] Building materials of equal area, thickness, and volume prepared in Examples 1-7 were subjected to water leaching tests under the same conditions. After leaching for 48 hours, the heavy metal content was measured, and the specific measurement results are shown in Table 2.

[0092] Table 2 shows the heavy metal concentration (unit: mg / L) of the leachate from simulated rainwater (pH 5.6) used in the building materials prepared by the triple curing technology of this invention.

[0093] Measurement items Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Cu 0.234 0.115 0.15 0.185 0.25 0.351 0.151 Zn 0.015 Not detected 0.18 0.28 Not detected Not detected 0.018 Ni Not detected Not detected 0.015 Not detected 0.018 Not detected Not detected Cd 0.020 0.015 0.026 Not detected 0.055 Not detected Not detected Cr 0.015 0.005 Not detected 0.018 0.025 Not detected Not detected Pb 0.043 0.078 Not detected 0.025 Not detected 0.0168 Not detected

[0094] According to the sludge brick leaching standard (GB5085.3-2007), as shown in Table 2, the building materials prepared by the method of this invention meet the hazardous waste identification standard. Furthermore, Table 2 shows that the building materials prepared by the triple solidification technology of this invention have good passivation and sealing effects on heavy metals in sludge.

[0095] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing building materials from sludge with excessive heavy metal content using a triple solidification technology, characterized in that: The method includes the following steps: S1: Material selection: 35-40 parts sludge, 5-10 parts iron ore slag, 70-80 parts lightweight aggregate, 5-20 parts fly ash, 2.8-3.2 parts sludge solidification agent; 5-20 parts cement, 25-100 parts sand; S2: Preparation of modified sludge: First, take the corresponding amount of sludge and put it into a mixer. Add the corresponding amount of sludge solidifying agent to the mixer. After the mixer is fully mixed, the heavy metals in the sludge are passivated. The mixed sludge is then subjected to high-efficiency sludge dewatering technology to maintain the relative dispersion between sludge particles, thus obtaining modified sludge. S3: High temperature treatment: The modified sludge after S2 dehydration treatment is placed in a high temperature furnace for baking. Under the action of high temperature, the water in the sludge is evaporated. Then the baked sludge is stirred to disperse the sludge and leave the heavy metals in the dust after high temperature treatment. The dust is collected by negative pressure. S4: Vibration Mixing: The dust treated by S3 high temperature and the corresponding amount of lightweight aggregate are put into a high-frequency vibrator for high-frequency vibration mixing. Combined with the effect of high-frequency vibration, the dust and its internal heavy metals penetrate into the pores of the lightweight aggregate, thus sealing the heavy metals in a secondary manner. S5: Preparation of modified slag: After crushing the iron ore slag, the iron ore slag is screened using a screening machine, and then magnetic separation is performed on the iron ore slag to remove useless and harmful metals, thus obtaining modified slag. S6: Raw material mixing: The dust and lightweight aggregate mixed by vibration in S4, the modified slag prepared in S5, and the remaining raw materials are put into a mixer for thorough mixing and stirring, and the heavy metals are sealed three times. S7: Molding: The raw materials that have been fully mixed in S6 are placed into a high-pressure molding machine and pressed into shape to obtain building materials.

2. The method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology according to claim 1, characterized in that: In step S2, sludge solidification agent is added to the mixer, and the mixing time is 10-20 minutes, with a mixing speed of 500-1000 r / min.

3. The method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology according to claim 1, characterized in that: In step S3, the modified sludge is placed in a high-temperature furnace and baked at a temperature of 100-120°C for 30-50 minutes.

4. The method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology according to claim 1, characterized in that: In step S4, the dust and lightweight aggregate are placed in a high-frequency oscillator and oscillated for 20-30 minutes, allowing the dust, along with its internal heavy metals, to penetrate into the pores of the lightweight aggregate.

5. The method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology according to claim 1, characterized in that: In step S5, the iron ore slag is screened using a screening machine to obtain iron ore slag with a diameter of 0.5-0.8 mm.

6. The method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology according to claim 1, characterized in that: In step S6, the time for fully mixing the materials in the mixer is 40-60 minutes, and the mixer speed is 600-1000 r / min.

7. The method for preparing building materials from sludge with excessive heavy metals using a triple solidification technology according to claim 1, characterized in that: In step S7, the molding pressure of the high-pressure molding machine is 0.4-0.6 MPa.

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