CN115215564A - Method for carbonizing and curing heavy metal in red mud by using wet method and application - Google Patents
Method for carbonizing and curing heavy metal in red mud by using wet method and application Download PDFInfo
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- CN115215564A CN115215564A CN202210602624.5A CN202210602624A CN115215564A CN 115215564 A CN115215564 A CN 115215564A CN 202210602624 A CN202210602624 A CN 202210602624A CN 115215564 A CN115215564 A CN 115215564A
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B7/00—Hydraulic cements
- C04B7/24—Cements from oil shales, residues or waste other than slag
- C04B7/243—Mixtures thereof with activators or composition-correcting additives, e.g. mixtures of fly ash and alkali activators
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B7/00—Hydraulic cements
- C04B7/22—Iron ore cements ; Iron rich cements, e.g. Ferrari cements, Kühl cements
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B7/00—Hydraulic cements
- C04B7/36—Manufacture of hydraulic cements in general
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B7/00—Hydraulic cements
- C04B7/36—Manufacture of hydraulic cements in general
- C04B7/38—Preparing or treating the raw materials individually or as batches, e.g. mixing with fuel
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
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Abstract
The invention discloses a method for carbonizing and curing red mud heavy metal by a wet method, which comprises the following steps: (1) Mixing red mud with water, and adjusting the solid content to 12.5-33.3% to obtain slurry A; (2) Taking 100 parts by weight of the slurry A, and carrying out wet grinding pulping to obtain slurry B, wherein the median particle size of solid particles in the slurry B is 2.3-3.9 mu m; (3) Taking 100 parts by weight of slurry B, adding 15-25 parts by weight of tailing slag and 1-5 parts by weight of dispersant, continuously wet grinding, and simultaneously introducing CO under pressure 2 Gas until the pH value of the slurry is reduced to 7-8 and the median particle size reaches 1.3-2.8 μm, and stopping wet grinding to obtain slurry C; the median particle size of the tailing slag is 40-80 μm; and (4) taking the slurry C as a cementing material to produce concrete. The invention is a new type of foodThe harmless treatment method of the mud can simultaneously realize carbon fixation and solidification of the heavy metal in the red mud, and the treated red mud can be directly applied to concrete production.
Description
Technical Field
The invention belongs to the technical field of red mud harmless treatment, and particularly relates to a method for carbonizing and curing red mud heavy metal by a wet method and application.
Background
Red mud is industrial waste slag produced after alumina is smelted in the metallurgical industry, and is called red mud because it contains a certain amount of iron oxide and thus appears red. 1-2 tons of wet red mud is produced for each 1 ton of alumina produced according to the prior art. The red mud generated after the Bayer process is used for producing alumina is called Bayer process red mud, the red mud generated in the Bayer process for producing alumina is close to 1.5 hundred million tons every year in the world, and the global red mud inventory is over 40 hundred million tons at present, and the national red mud inventory is over 11 hundred million tons. Due to the continuous increase of the demand of nonferrous aluminum metals, the alumina industry is in a rapid expansion trend, which also leads to the gradual increase of the yield of red mud, but the utilization rate is only 4%, the comprehensive utilization rate is low, and most of the red mud still exists in the form of open-air stockpiling.
The red mud has the characteristics of high alkalinity, complex chemical components, low permeability, high dispersibility and the like, the particle size of the red mud raw powder is small, and the simple open-air stockpiling is easy to pollute the acid-base property of the surrounding land, the air environment and the underground water through the ways of land erosion, dust raising, rainwater infiltration and the like. The chemical composition of the red mud comprises CaO and Fe 2 O 3 、SiO 2 、MgO、Al 2 O 3 、Na 2 O、K 2 O and the like, and also contains heavy metal elements such as Cr, cu, pb and the like, and if the red mud is not reasonably treated and stockpiled, the environmental pollution will be seriously threatened.
With the development of science and technology and the progress of industry, CO worldwide 2 The emission increases year by year due to CO 2 The caused greenhouse effect, the global average temperature is increased by 2 ℃, and the problems of glacier melting, sea level rising, extreme weather increase, natural ecosystem destruction and the like are caused. How to convert CO 2 The method carries out green resource utilization, achieves the aim of environmental protection, and is also the key scientific technology which needs to be solved at presentThe problem of operation is difficult.
Because the red mud has high alkalinity and pH value of about 11-13 and contains elements such as Ca, mg and the like, the red mud has certain carbon fixation potential and can be used with CO 2 The reaction generates stable carbonate products, which can reduce the alkalinity of the red mud on one hand and can also reduce the industrial tail gas CO on the other hand 2 And curing and sealing.
The carbon fixation and heavy metal fixation of red mud are related to the prior art. In the chinese patent application No. 202110950235.7, a passivation method of heavy metals in red mud is disclosed, in which a chemical reagent is used to adjust the pH value, the cost is high, and the actual utilization rate is low. In the chinese patent application No. 202011489290.2, a method for carbon fixation of highly alkaline alumina red mud is disclosed, which utilizes red mud carbon fixation to prepare ammonium bicarbonate, but does not consider heavy metal pollution in red mud. In the chinese patent application No. 201910829608.8, a preparation method of modified red mud capable of absorbing and solidifying the encapsulated carbon dioxide is disclosed, but the preparation method requires high-temperature activation, high-temperature calcination, drying in an oven and other processes, and has complex process flow and high energy consumption.
At present, a method for simultaneously fixing carbon and solidifying heavy metal by using red mud is not available.
Disclosure of Invention
The invention aims to provide a method for carbonizing and solidifying red mud heavy metal by a wet method.
The invention relates to a novel red mud harmless treatment method, which mainly utilizes industrial tail gas CO 2 The red mud is carbonized, the alkalinity of the red mud is reduced, heavy metals in the red mud are solidified, so that the purposes of treating wastes with wastes and being environment-friendly are achieved, and the treated red mud has the advantages of low alkalinity, low heavy metal ion dissolution and good stability, and can be directly applied to concrete production.
The invention provides a method for carbonizing and solidifying red mud heavy metal by a wet method, which comprises the following steps:
(1) Taking red mud yard raw materials, adding water for mixing, and adjusting the solid content to 12.5-33.3% to obtain slurry A; the water adding amount can be determined according to the actual water content of the red mud raw material, and the solid content in the slurry A is ensured to be 12.5-33.3%; the solid content is the mass percentage of the dry red mud in the slurry;
(2) Wet grinding 100 weight parts of slurry A until the median particle size of solid particles in the slurry is 2.3-3.9 μm to obtain slurry B;
(3) Taking 100 parts by weight of slurry B, adding 15-25 parts by weight of tailing slag and 1-5 parts by weight of dispersant, continuously wet-grinding, and introducing CO 2 Gas until the pH value of the slurry is reduced to 7-8 and the median particle size of solid particles in the slurry reaches 1.3-2.8 mu m, and stopping wet grinding to obtain slurry C; the median particle size of the tailing slag is 40-80 μm;
(4) Taking the slurry C as a cementing material to produce concrete, thereby realizing CO 2 And permanent storage of heavy metals.
The invention is realized by introducing CO in the wet grinding process 2 Gas is fully dispersed in the red mud particles through mechanical force and wet grinding balls, the red mud particles are fully contacted with water molecules, the dissolution of heavy metal ions in the particles is further promoted, and the dissolved heavy metal ions are dispersed in a liquid phase environment and are mixed with CO 2 After the contact, the reaction occurs to generate insoluble carbonate and fix part of heavy metals. The addition of the tailing slag can reduce high-valence toxic heavy metals in the red mud to a low valence state by utilizing substances such as reducing Fe, feO, mnO and the like in the tailing slag; simultaneously CaO and MgO in the tailing slag can better solidify CO 2 . The red mud slurry after carbon fixation and heavy metal curing can be directly mixed into concrete, thereby realizing CO treatment 2 And permanent storage of heavy metals.
In some embodiments, the red mud is produced after alumina is produced by a Bayer process, and comprises calcite, quartz, sodalite, diaspore, calcium silicate, calcium aluminosilicate, chromate and ferric oxide, wherein the pH value is 11-13, the radioactivity internal and external radiation indexes are within 1.0mSv/y, and the median particle size is 5-10 μm.
In some embodiments, the tailings are a mixture of one or more of iron tailings, copper tailings, graphite tailings, or quarrying tailings.
In some embodiments, the dispersant is a mixture of one or more of sodium hexametaphosphate, sodium polycarboxylate, or calcium polyacrylate.
In some embodiments, in step (2) and step (3), wet grinding balls with a ball diameter of 2.0-2.5 mm are used, and the ball-to-material ratio of the wet grinding balls is (1-3): (3-1); the wet grinding rotating speed is 100-500 r/min.
Furthermore, the wet grinding balls are one or a mixture of more of zirconia balls, agate balls and stainless steel balls.
In some embodiments, CO is used in step (3) 2 For purifying and trapping CO in industrial production tail gas 2 The purity is more than 90%.
In some embodiments, CO is used in step (3) 2 The aeration pressure of (A) is 0.1-0.4 MPa.
In some embodiments, slurry C is incorporated into the concrete in step (4) in place of 5% to 30% cementitious material.
Compared with the prior art, the invention has the advantages that:
(1) The method for carbonizing and curing red mud heavy metal by using the wet method can fully break the red mud particles in the wet grinding stage, increase the contact area of water and the red mud particles, improve ion dissolution, and utilize the liquid phase environment to ensure that the dissolved heavy metal ions and CO are dissolved 2 Reacting, and solidifying heavy metal;
(2) According to the method for curing the heavy metal in the red mud by wet carbonization, provided by the invention, the high alkalinity of the red mud, the high Ca and Mg content and other carbon-fixing potentials can be utilized in the carbon-fixing stage to cure and seal the industrial tail gas CO2, so that on one hand, the CO discharged by the industrial tail gas is consumed 2 On the other hand, the alkalinity of the red mud is reduced, and the application at the rear end is facilitated;
(3) The method for carbonizing and curing the heavy metal in the red mud by the wet method provided by the invention can be used for producing the concrete by using the red mud slurry which is generated in the later stage and has low alkalinity, high stability and low heavy metal ion dissolution 2 And the permanent storage of heavy metals, and the current concrete has large production capacity and large consumption, thereby being a reliable way for the resource utilization of the red mud.
Detailed Description
The following examples are provided to further illustrate the present invention for better understanding, but the present invention is not limited to the following examples.
In the examples and comparative examples, the red mud used in the examples is red mud produced after alumina production by the Bayer process, and the components comprise calcite, quartz, sodalite, diaspore, calcium silicate, calcium aluminosilicate, chromate and ferric oxide, the pH value is 11-13, the radioactivity internal and external illumination index is within 1.0mSv/y, and the median particle size is 5-10 μm. CO used 2 For purifying and trapping CO in industrial production tail gas 2 The purity is more than 90 percent.
Example 1
The specific steps of this example are as follows:
(1) Taking red mud yard raw materials, adding water, mixing, and adjusting the solid content to 33.3% to obtain slurry A.
(2) Taking 100 parts by weight of slurry A, selecting zirconia balls with the ball diameter of 2.0-2.5 mm, and mixing the slurry A with the zirconia balls in a ball-to-material ratio of 1:1, wet grinding and pulping at the rotating speed of 300r/min to obtain slurry B, wherein the median diameter of solid particles in the slurry B is 3.3 mu m.
(3) Taking 100 parts by weight of the slurry B, adding 80 mu m of median particle diameter, 25 parts by weight of iron tailing slag and 5 parts by weight of sodium hexametaphosphate, continuing wet grinding, and simultaneously introducing CO with the pressure of 0.1MPa 2 And carbonizing the gas until the pH value of the slurry is reduced to 7.6 and the median particle size reaches 2.1 mu m, and stopping wet grinding to obtain slurry C.
(4) The slurry C is taken to partially replace cement and is doped into concrete raw materials, thereby realizing the aim of CO 2 And permanent storage of heavy metals.
In this embodiment, the concrete is C30 concrete, and the mixing ratio thereof is: 150kg/m water 3 42.5 ordinary Portland cement 220kg/m 3 90kg/m of fly ash 3 30kg/m of mineral powder 3 Machine-made sand 408kg/m 3 408kg/m of river sand 3 1080kg/m of pebbles 3 6.8kg/m of additive 3 The water-to-gel ratio was 0.44.
The mixing amount of the slurry C is selected from 5%, 15% and 25% to replace the using amount of the ordinary portland cement, namely the total amount of the slurry C and the cement is 220kg/m < 3 >, wherein the mass percentages of the slurry C are 5%, 15% and 25% respectively.
Centrifuging the slurry C to obtain supernatant, and testing the dissolution of heavy metal ions by using ICP; after vacuum drying, TG is used for testing carbon fixation rate. Adding the slurry C into concrete, placing the concrete in a standard curing room, curing the concrete to 28d of age to obtain a test block, and testing the 28d compressive strength of the test block; and (4) soaking a test block to test heavy metal toxicity leaching. The compressive strength test is evaluated according to GB/T50107-2010 concrete strength test evaluation standard, and the toxic leaching is evaluated according to GB 5085.3-2007 hazardous waste identification standard leaching toxicity identification. The performance data for slurry C and the test block are shown in tables 1-2.
Example 2
The specific steps of this example are as follows:
(1) Taking red mud yard raw materials, adding water, mixing, and adjusting the solid content to 20% to obtain slurry A.
(2) Taking 100 parts by weight of the slurry A, selecting agate balls with the ball diameter of 2.0-2.5 mm, and mixing the slurry A with the agate balls according to a ball-material ratio of 2:1, carrying out wet grinding pulping at the rotating speed of 100r/min to obtain slurry B, wherein the median particle size of solid particles in the slurry B is 3.9 mu m.
(3) Adding 20 parts by weight of graphite tailing slag and 3 parts by weight of calcium polyacrylate into 100 parts by weight of slurry B with the median particle size of 60 mu m, continuously wet-grinding, and introducing CO with the pressure of 0.3MPa 2 Carbonizing the slurry by gas until the pH value of the slurry is reduced to 7.1 and the median particle size reaches 2.8 mu m, and stopping wet grinding to obtain slurry C.
(4) The slurry C is taken to partially replace cement and is doped into concrete raw materials, thereby realizing the aim of CO 2 And permanent containment of heavy metals.
In this embodiment, the concrete is C30 concrete, and the mixing ratio thereof is: 150kg/m water 3 42.5 ordinary Portland cement 220kg/m 3 90kg/m of fly ash 3 30kg/m of mineral powder 3 Machine-made sand 408kg/m 3 408kg/m of river sand 3 1080kg/m of pebbles 3 6.8kg/m of additive 3 The water-to-glue ratio was 0.44.
The mixing amount of the slurry C is 10%, 20% and 30% to replace the using amount of the ordinary portland cement, namely the total amount of the slurry C and the cement is 220kg/m < 3 >, wherein the mass percentages of the slurry C are 10%, 20% and 30% respectively.
Centrifuging the slurry C to obtain supernatant, and testing the dissolution of heavy metal ions by using ICP; after vacuum drying, the carbon fixation rate was measured by TG. Adding the slurry C into concrete, placing the concrete in a standard curing room, curing the concrete to 28d of age to obtain a test block, and testing the 28d compressive strength of the test block; and (4) soaking a test block to test heavy metal toxicity leaching. The compressive strength test is evaluated according to GB/T50107-2010 concrete strength test evaluation standard, and the toxic leaching is evaluated according to GB 5085.3-2007 hazardous waste identification standard leaching toxicity identification. The performance data for slurry C and the test block are shown in tables 1-2.
Example 3
The specific steps of this example are as follows:
(1) Taking red mud yard raw materials, adding water, mixing, and adjusting the solid content to be 14.3% to obtain slurry A.
(2) Taking 100 parts by weight of slurry A, selecting stainless steel balls with the ball diameter of 2.0-2.5, wherein the ball-material ratio is 1: and 2, carrying out wet grinding and pulping at the rotating speed of 500r/min to obtain slurry B, wherein the median particle size of solid particles in the slurry B is 2.2 mu m.
(3) Taking 100 parts by weight of the slurry B, adding the quarrying tailing slag with the median particle size of 40 mu m and 15 parts by weight and 2 parts by weight of sodium polycarboxylate, continuously wet-grinding, and introducing CO with the pressure of 0.2MPa 2 Carbonizing the slurry by gas until the pH value of the slurry is reduced to 7.3 and the median particle size reaches 1.4 mu m, and stopping wet grinding to obtain slurry C.
(4) The slurry C is taken to partially replace cement and is doped into concrete raw materials, thereby realizing the aim of CO 2 And permanent containment of heavy metals.
In this embodiment, the concrete is C25 concrete, and the mix ratio thereof is: 150kg/m water 3 190kg/m of 42.5 ordinary portland cement 3 90kg/m of fly ash 3 30kg/m of mineral powder 3 Machine-made sand 413kg/m 3 413kg/m of river sand 3 1100kg/m stone 3 6.2kg/m of additive 3 The water-to-glue ratio was 0.48.
The mixing amount of the slurry C is selected from 5%, 15% and 25% to replace the using amount of the ordinary portland cement, namely the total amount of the slurry C and the cement is 190kg/m < 3 >, wherein the mass percentages of the slurry C are 5%, 15% and 25% respectively.
Centrifuging the slurry C to obtain supernatant, and testing heavy metal ion dissolution by using ICP (inductively coupled plasma); after vacuum drying, the carbon fixation rate was measured by TG. Mixing the slurry C into concrete, placing the concrete in a standard curing room for curing to 28d age to obtain a test block, and testing the 28d compressive strength of the test block; and (5) taking a test block to soak for testing the heavy metal toxicity leaching. The compressive strength test is evaluated according to GB/T50107-2010 concrete strength test evaluation standard, and the toxic leaching is evaluated according to GB 5085.3-2007 hazardous waste identification standard leaching toxicity identification. The performance data for slurry C and the test block are shown in tables 1-2.
Example 4
The specific steps of this example are as follows:
(1) Taking red mud yard raw materials, adding water, mixing, and adjusting the solid content to 25% to obtain slurry A.
(2) Taking 100 parts by weight of the slurry A, selecting agate balls with the ball diameter of 2.0-2.5, wherein the ball-material ratio is 3:1, wet grinding and pulping at the rotating speed of 400r/min to obtain slurry B, wherein the median particle size of solid particles in the slurry B is 2.6 mu m.
(3) 100 parts by weight of the slurry B was taken, added with 24 parts by weight of copper tailings slag having a median particle diameter of 50 μm and 1 part by weight of sodium hexametaphosphate, wet-milled continuously while introducing CO at a pressure of 0.4MPa 2 Carbonizing the slurry by gas until the pH value of the slurry is reduced to 7.2 and the median particle size reaches 1.7 mu m, and stopping wet grinding to obtain slurry C.
(4) Taking the slurry C to partially replace cement and doping the slurry C into concrete raw materials, thereby realizing CO separation 2 And permanent containment of heavy metals.
In this embodiment, the concrete is C25 concrete, and the mix ratio thereof is: 150kg/m water 3 42.5 ordinary Portland cement 190kg/m 3 90kg/m of fly ash 3 30kg/m of mineral powder 3 Machine-made sand 413kg/m 3 413kg/m of river sand 3 1100kg/m of stone 3 6.2kg/m of additive 3 The water-to-glue ratio was 0.48.
The mixing amount of the slurry C is 10 percent, 20 percent and 30 percent to replace the using amount of the ordinary Portland cement, namely the total amount of the slurry C and the cement is 190kg/m 3 Wherein the mass percentages of the sizing agent C are respectively 10%, 20% and 30%.
Centrifuging the slurry C to obtain supernatant, and testing the dissolution of heavy metal ions by using ICP; after vacuum drying, the carbon fixation rate was measured by TG. Adding the slurry C into concrete, placing the concrete in a standard curing room, curing the concrete to 28d of age to obtain a test block, and testing the 28d compressive strength of the test block; and (5) taking a test block to soak for testing the heavy metal toxicity leaching. The compressive strength test is evaluated according to GB/T50107-2010 concrete strength test evaluation standard, and the toxic leaching is evaluated according to GB 5085.3-2007 hazardous waste identification standard leaching toxicity identification. The performance data for slurry C and the test block are shown in tables 1-2.
Example 5
The specific steps of this example are as follows:
(1) Taking the red mud yard raw material, adding water, mixing, and adjusting the solid content to 12.5% to obtain the slurry A.
(2) Taking 100 parts by weight of slurry A, selecting stainless steel with the sphere diameter of 2.0-2.5, and mixing the slurry A with the slurry A in a ratio of 1: and 3, performing wet grinding pulping at the rotation speed of 200r/min to obtain slurry B, wherein the median particle size of solid particles in the slurry B is 3.7 mu m.
(3) Taking 100 parts by weight of the slurry B, adding 18 parts by weight of iron tailing slag with the median particle size of 80 mu m and 3 parts by weight of sodium polycarboxylate, continuously wet-grinding, and introducing CO with the pressure of 0.1MPa 2 Carbonizing the slurry by gas until the pH value of the slurry is reduced to 7.8 and the median particle size reaches 2.7 mu m, and stopping wet grinding to obtain slurry C.
(4) Taking the slurry C to partially replace cement and doping the slurry C into concrete raw materials, thereby realizing CO separation 2 And permanent sealing of heavy metals.
In this embodiment, the concrete is C15 concrete, and the mix ratio thereof is: 180kg/m water 3 42.5 ordinary Portland cement 70kg/m 3 150kg/m of fly ash 3 Machine-made sand 430kg/m 3 430kg/m river sand 3 1100kg/m of stone 3 The water-to-glue ratio was 0.82.
The mixing amount of the slurry C is selected from 5%, 15% and 25% to replace the using amount of the ordinary Portland cement, namely the total amount of the slurry C and the cement is 70kg/m 3 Wherein the mass percentages of the sizing agent C are 5 percent, 15 percent and 25 percent respectively.
Centrifuging the slurry C to obtain supernatant, and testing heavy metal ion dissolution by using ICP (inductively coupled plasma); after vacuum drying, the carbon fixation rate was measured by TG. Adding the slurry C into concrete, placing the concrete in a standard curing room, curing the concrete to 28d of age to obtain a test block, and testing the 28d compressive strength of the test block; and (5) taking a test block to soak for testing the heavy metal toxicity leaching. The compressive strength test is evaluated according to GB/T50107-2010 concrete strength test evaluation standard, and the toxicity leaching is evaluated according to GB 5085.3-2007 hazardous waste identification standard leaching toxicity identification. The performance data for slurry C and the test block are shown in tables 1-2.
Example 6
The specific steps of this example are as follows:
(1) Taking red mud yard raw materials, adding water, mixing, and adjusting the solid content to 16.7% to obtain slurry A.
(2) Taking 100 parts by weight of slurry A, selecting zirconia balls with the ball diameter of 2.0-2.5, wherein the ball-to-material ratio is 2:1, wet grinding and pulping at the rotating speed of 400r/min to obtain slurry B, wherein the median particle size of solid particles in the slurry B is 2.3 mu m.
(3) Taking 100 parts by weight of the slurry B, adding 40 mu m of median particle diameter, 20 parts by weight of quarrying tailing slag and 4 parts by weight of calcium polyacrylate, continuously wet-grinding, and simultaneously introducing CO with the pressure of 0.2MPa 2 And carbonizing the gas until the pH value of the slurry is reduced to 7.1 and the median particle size reaches 1.3 mu m, and stopping wet grinding to obtain slurry C.
(4) Taking the slurry C to partially replace cement and doping the slurry C into concrete raw materials, thereby realizing CO separation 2 And permanent storage of heavy metals.
In this embodiment, the concrete is C15 concrete, and the mix ratio thereof is: 180kg/m < 3 > of water, 70kg/m < 3 > of 42.5 ordinary portland cement, 150kg/m < 3 > of fly ash, 430kg/m < 3 > of machine-made sand, 430kg/m < 3 > of river sand, 1100kg/m < 3 > of stones and 0.82 of water-cement ratio.
The mixing amount of the slurry C is 10%, 20% and 30% to replace the using amount of the ordinary Portland cement, namely the total amount of the slurry C and the cement is 70kg/m 3 Wherein the mass percentages of the sizing agent C are respectively 10%, 20% and 30%.
Centrifuging the slurry C to obtain supernatant, and testing the dissolution of heavy metal ions by using ICP; after vacuum drying, the carbon fixation rate was measured by TG. Adding the slurry C into concrete, placing the concrete in a standard curing room, curing the concrete to 28d of age to obtain a test block, and testing the 28d compressive strength of the test block; and (4) soaking a test block to test heavy metal toxicity leaching. The compressive strength test is evaluated according to GB/T50107-2010 concrete strength test evaluation standard, and the toxicity leaching is evaluated according to GB 5085.3-2007 hazardous waste identification standard leaching toxicity identification. The performance data for slurry C and the test block are shown in tables 1-2.
Table 1 test data for slurries obtained in examples 1 to 6
Table 2 test data for concrete obtained in examples 1 to 6
In examples 1 to 6, the solid carbon ratio was calculated by analyzing the TG test results, and the specific method was as follows:
carbonate is decomposed into oxide and CO at 550-800 deg.C 2 With weight loss of m 1 Denotes the mass of the sample before decomposition, m 2 Expressed as mass of the sample after decomposition, m 1 -m 2 Namely the CO lost by the thermal decomposition sample 2 So carbon fixation rate = (m) 1 -m 2 )/m 1 ×100％。
The foregoing description of specific exemplary embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.
Claims (10)
1. A method for carbonizing and solidifying red mud heavy metal by a wet method is characterized by comprising the following steps:
(1) Adding water into the red mud for mixing, and adjusting the solid content to be 12.5-33.3% to obtain slurry A;
(2) Wet grinding 100 parts by weight of the slurry A until the median particle size of solid particles in the slurry is 2.3-3.9 μm to obtain slurry B;
(3) Taking 100 parts by weight of slurry B, adding 15-25 parts by weight of tailing slag and 1-5 parts by weight of dispersant, continuously wet grinding, and introducing CO 2 Gas until the pH value of the slurry is reduced to 7-8 and the median particle size of solid particles in the slurry reaches 1.3-2.8 mu m, and stopping wet grinding to obtain slurry C;
(4) Taking the slurry C as a cementing material to produce concrete.
2. The method for curing the heavy metals in the red mud by wet carbonization according to claim 1, is characterized in that:
the red mud is produced after alumina is produced by a Bayer process, the pH value of the red mud is 11-13, and the median particle size is 5-10 mu m.
3. The method for solidifying the red mud heavy metal by wet carbonization according to claim 1, which is characterized in that:
the tailing slag is one or a mixture of iron tailing slag, copper tailing slag, graphite tailing slag or quarrying tailing slag.
4. The method for solidifying the red mud heavy metal by wet carbonization according to claim 1, which is characterized in that:
the median particle size of the tailing slag is 40-80 μm.
5. The method for solidifying the red mud heavy metal by wet carbonization according to claim 1, which is characterized in that:
the dispersing agent is one or a mixture of sodium hexametaphosphate, sodium polycarboxylate or calcium polyacrylate.
6. The method for solidifying the red mud heavy metal by wet carbonization according to claim 1, which is characterized in that:
in the wet grinding process of the step (2) and the step (3), wet grinding balls with the ball diameter of 2.0-2.5 mm are adopted, and the ball material ratio of the wet grinding balls is (1-3): (3-1); the wet grinding rotating speed is 100-500 r/min.
7. The method for solidifying the red mud heavy metal by wet carbonization according to claim 1, which is characterized in that:
the wet grinding balls are one or a mixture of more of zirconia balls, agate balls and stainless steel balls.
8. The method for curing the heavy metals in the red mud by wet carbonization according to claim 1, is characterized in that:
CO in step (3) 2 For purifying and trapping CO in industrial production tail gas 2 The purity is more than 90%.
9. The method for solidifying the red mud heavy metal by wet carbonization according to claim 1, which is characterized in that:
CO in step (3) 2 The aeration pressure of (A) is 0.1-0.4 MPa.
10. The method for curing the heavy metals in the red mud by wet carbonization according to claim 1, is characterized in that:
and (4) mixing the slurry C into concrete to replace 5-30% of cementing materials.
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| CN116161880A (en) * | 2023-03-06 | 2023-05-26 | 湖北工业大学 | Preparation method of carbon-fixation early-strength high-performance magnesium slag-based wet cementing material |
| US11958788B2 (en) * | 2022-05-30 | 2024-04-16 | Hubei University Of Technology | Method of preparing alkali activation material by using red mud-based wet grinding and carbon sequestration and application thereof |
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| CN110981378A (en) * | 2019-12-18 | 2020-04-10 | 湖北工业大学 | Method for solidifying chromium-containing solid waste |
| CN113800792A (en) * | 2021-09-13 | 2021-12-17 | 河南理工大学 | Method for activating sintering-process red mud by in-situ wet carbonization at room temperature, activated red mud and application thereof |
| CN113896466A (en) * | 2021-10-28 | 2022-01-07 | 山东汉博昱洲新材料有限公司 | Red mud consolidation method based on carbonation reaction and obtained carbonized product |
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| CN110981378A (en) * | 2019-12-18 | 2020-04-10 | 湖北工业大学 | Method for solidifying chromium-containing solid waste |
| CN113800792A (en) * | 2021-09-13 | 2021-12-17 | 河南理工大学 | Method for activating sintering-process red mud by in-situ wet carbonization at room temperature, activated red mud and application thereof |
| CN113896466A (en) * | 2021-10-28 | 2022-01-07 | 山东汉博昱洲新材料有限公司 | Red mud consolidation method based on carbonation reaction and obtained carbonized product |
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| US11958788B2 (en) * | 2022-05-30 | 2024-04-16 | Hubei University Of Technology | Method of preparing alkali activation material by using red mud-based wet grinding and carbon sequestration and application thereof |
| CN116161880A (en) * | 2023-03-06 | 2023-05-26 | 湖北工业大学 | Preparation method of carbon-fixation early-strength high-performance magnesium slag-based wet cementing material |
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