CN115215564B - Method for carbonizing and curing heavy metal in red mud by wet method and application - Google Patents

Method for carbonizing and curing heavy metal in red mud by wet method and application Download PDF

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CN115215564B
CN115215564B CN202210602624.5A CN202210602624A CN115215564B CN 115215564 B CN115215564 B CN 115215564B CN 202210602624 A CN202210602624 A CN 202210602624A CN 115215564 B CN115215564 B CN 115215564B
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slurry
red mud
wet
heavy metal
weight
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CN115215564A (en
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杨进
李韦龙
贺行洋
苏英
郑正旗
陈顺
段晓鹏
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Hubei University of Technology
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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
    • 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
    • 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
    • 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
    • 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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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Treatment Of Sludge (AREA)

Abstract

The invention discloses a method for carbonizing and curing red mud heavy metal by a wet method, which comprises 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) 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 mu m; and (4) taking the slurry C as a cementing material to produce concrete. The invention is a novel harmless treatment method of red mud, which can simultaneously realize carbon fixation and red mud heavy metal solidification, and the treated red mud can be directly applied to concrete production.

Description

Method for carbonizing and curing heavy metal in red mud by wet method and application
Technical Field
The invention belongs to the technical field of red mud harmless treatment, and particularly relates to a method for carbonizing and curing heavy metals in red mud by using a wet method and application.
Background
Red mud is industrial waste slag generated after smelting alumina in the metallurgical industry, and is called red mud because it contains a certain amount of iron oxide and thus is red. 1-2 tons of wet red mud is produced for every 1 ton of alumina produced according to the prior art. The red mud generated after alumina is produced by a Bayer process is called Bayer process red mud, the red mud generated by alumina production by the Bayer process is close to 1.5 hundred million tons every year in the world, and the red mud inventory in China exceeds 11 hundred million tons by the current global red mud inventory. Due to the increasing demand of nonferrous aluminum metals, the alumina industry is always in a rapid expansion trend, which also leads to the gradual increase of the yield of the red mud, but the utilization rate is only 4 percent, 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 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 is 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 has the advantages of green resource utilization, environment-friendly purpose, and is a key scientific and technical problem which needs to be solved at present.
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 and can also reduce the CO in industrial tail gas 2 And curing and sealing.
The carbon fixation and heavy metal fixation of red mud are related to the prior art. In chinese patent application No. 202110950235.7, a passivation method of heavy metals in red mud is disclosed, in which chemical reagents are 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 curing 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 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; 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 containment 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 contact, the reaction takes place to form insolubilityCarbonate, fixing part of heavy metals. The addition of the tailing slag can reduce the 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 (2) 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 the red mud heavy metal by the wet method can fully crush the red mud in the wet grinding stageThe red mud particles increase the contact area of water and the red mud particles, improve ion dissolution, and utilize a liquid phase environment to ensure that the dissolved heavy metal ions and CO 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 curing the heavy metal in the red mud by wet carbonization 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, thereby realizing CO separation 2 And the permanent storage of heavy metals, and the production volume and the consumption of the concrete are large at present, so that the method is 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) Get 100Adding 25 parts by weight of iron tailing slag and 5 parts by weight of sodium hexametaphosphate into the slurry B with the median particle size of 80 mu m by weight, and continuously wet-grinding while introducing CO with the pressure of 0.1MPa 2 Carbonizing the slurry by gas until the pH value of the slurry is reduced to 7.6 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 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-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, 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 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, wet grinding and pulping at the rotating speed of 100r/min to obtain slurry B, wherein the median diameter of solid particles in the slurry B is 3.9 mu m.
(3) Taking 100 parts by weight of pulpAdding 20 parts by weight of graphite tailing slag and 3 parts by weight of calcium polyacrylate into material B with the median particle size of 60 mu m, continuously wet-grinding, and simultaneously introducing CO with the pressure of 0.3MPa 2 And carbonizing the 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 mix 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 River sediment 408kg/m 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 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 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 15 parts by weight of quarrying tailing slag with the median particle size of 40 mu m and 2 parts by weight of sodium polycarboxylate, continuously wet-grinding, and simultaneously 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 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 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 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 (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 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) Taking 100 parts by weight of slurry B, adding the median particles24 parts by weight of copper tailings slag having a diameter of 50 μm and 1 part by weight of sodium hexametaphosphate were wet-milled continuously while feeding 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 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 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. 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 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 5
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 12.5% to obtain 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, carrying out wet grinding and pulping at the rotating 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 slurry B, adding the medium particle size80 μm, 18 parts by weight of iron tailings and 3 parts by weight of sodium polycarboxylate, and continuously wet-grinding while feeding CO at a 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 the dissolution of heavy metal ions by using ICP; after vacuum drying, TG is used for testing carbon fixation rate. 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 (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.
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 20 parts by weight of quarrying tailing slag and 4 parts by weight of calcium polyacrylate into the slurry B, and then addingWet grinding while introducing CO under 0.2MPa 2 Carbonizing the slurry by 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) 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 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 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 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.
Table 1 test data for slurries obtained in examples 1 to 6
Figure GDA0004051179650000091
Figure GDA0004051179650000101
Table 2 test data for concrete obtained in examples 1 to 6
Figure GDA0004051179650000102
Figure GDA0004051179650000111
In examples 1 to 6, the solid carbon ratio was calculated by analyzing the TG test results, and the specific method was as follows:
the 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 descriptions of specific exemplary embodiments of the present invention have been presented for 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 (9)

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;
the tailing slag is one or a mixture of iron tailing slag, copper tailing slag, graphite tailing slag or quarrying tailing slag.
2. The method for solidifying the red mud heavy metal by wet carbonization according to claim 1, which is characterized in that:
the red mud is produced after alumina is produced by a Bayer process, the pH value is 11-13, and the median particle size is 5-10 mu m.
3. The method for curing the heavy metals in the red mud by wet carbonization according to claim 1, is characterized in that:
the median particle size of the tailing slag is 40-80 μm.
4. 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.
5. 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.
6. The method for curing the heavy metals in the red mud by wet carbonization according to claim 5, is characterized in that:
the wet grinding balls are one or a mixture of more of zirconia balls, agate balls and stainless steel balls.
7. 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 For purifying and trapping CO in industrial production tail gas 2 The purity is more than 90%.
8. 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.
9. The method for solidifying the red mud heavy metal by wet carbonization according to claim 1, which is characterized in that:
in the step (4), the slurry C is doped into concrete to replace 5-30% of cementing materials.
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