CN106588117B - Radiation-proof functional aggregate prepared from electroplating sludge containing Cr and Zn - Google Patents

Radiation-proof functional aggregate prepared from electroplating sludge containing Cr and Zn Download PDF

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CN106588117B
CN106588117B CN201611142289.6A CN201611142289A CN106588117B CN 106588117 B CN106588117 B CN 106588117B CN 201611142289 A CN201611142289 A CN 201611142289A CN 106588117 B CN106588117 B CN 106588117B
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aggregate
radiation
percent
proof
equal
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CN106588117A (en
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丁庆军
刘勇强
王承
张杨
耿春东
刘凯
徐意
石华
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Wuhan University of Technology WUT
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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
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
    • C04B41/81—Coating or impregnation
    • C04B41/85—Coating or impregnation with inorganic materials
    • 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
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • C04B28/04—Portland 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
    • C04B33/00—Clay-wares
    • C04B33/02—Preparing or treating the raw materials individually or as batches
    • C04B33/04—Clay; Kaolin
    • 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
    • C04B33/00—Clay-wares
    • C04B33/02—Preparing or treating the raw materials individually or as batches
    • C04B33/13—Compounding ingredients
    • C04B33/132—Waste materials; Refuse; Residues
    • 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
    • C04B33/00—Clay-wares
    • C04B33/02—Preparing or treating the raw materials individually or as batches
    • C04B33/13—Compounding ingredients
    • C04B33/132—Waste materials; Refuse; Residues
    • C04B33/1325—Hazardous waste other than combustion residues
    • C04B33/1327—Hazardous waste other than combustion residues containing heavy metals
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    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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    • C04B33/00—Clay-wares
    • C04B33/32—Burning methods
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    • 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
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • 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
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00017—Aspects relating to the protection of the environment
    • 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
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00025—Aspects relating to the protection of the health, e.g. materials containing special additives to afford skin protection
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    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00482—Coating or impregnation materials
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    • C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/20—Mortars, concrete or artificial stone characterised by specific physical values for the density
    • C—CHEMISTRY; METALLURGY
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    • C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
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    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/60—Production of ceramic materials or ceramic elements, e.g. substitution of clay or shale by alternative raw materials, e.g. ashes

Abstract

The invention discloses a radiation-proof functional aggregate prepared by electroplating sludge containing Cr and Zn, which utilizes the characteristic that heavy metal elements Cr and Zn have excellent shielding performance on high-energy rays to ensure that the regenerated aggregate has excellent radiation-proof performance; carrying out slurry wrapping treatment on the regenerated aggregate by using a vacuum stirring technology, and optimizing the surface structure of the aggregate; the autoclaved curing is utilized to carry out ultrahigh performance treatment on the aggregate after slurry wrapping, so that the mechanical property, the shielding property and the curing effect of heavy metal ions are improved. The radiation-proof functional aggregate provided by the invention not only solves the problem of poor homogeneity of natural high-density ore radiation-proof concrete, but also can absorb a large amount of heavy metal-containing industrial sludge, and has important significance for preparation of radiation-proof concrete and treatment of industrial sludge.

Description

Radiation-proof functional aggregate prepared from electroplating sludge containing Cr and Zn
Technical Field
The invention belongs to the field of building materials, and particularly relates to radiation-proof functional aggregate prepared from electroplating sludge containing Cr and Zn and a preparation method thereof.
Background
The domestic household appliances and electronic devices are rapidly updated, so that the electroplating industry and other industries in China are rapidly developed, and the treatment of the electroplating sludge and other industrial wastes becomes a prominent environmental protection problem. Sludge and waste residues generated in the electroplating industry are mixed wastes rich in various heavy metal components, are one of industrial wastes with high harmfulness, and have annual discharge capacity of more than 40 million tons. The electroplating sludge contains high heavy metal content, wherein the heavy metal elements of Cr and Zn are respectively up to about 13 percent and 4 percent, the heavy metal discharged by the sludge per year can reach more than 10 ten thousand tons, and the electroplating sludge has harm to the alimentary canal, respiratory tract, skin and the like of a human body and poses threat to the living environment of human beings.
At present, the development of nuclear science and technology and the utilization of nuclear energy are one of the most great achievements of human beings in the 20 th century, a protective body for shielding radioactive rays needs to be arranged around a structure with a radiation source, and radiation-proof concrete plays an increasingly important role in nuclear shielding building materials of hospitals, nuclear power plants and some scientific research institutions with nuclear facilities due to excellent ray shielding performance, durability and mechanical performance. At present, the radiation-proof concrete taking barite as aggregate is widely adopted in China, but the following problems exist: firstly, high-density natural ore (barite, magnetite ore or limonite) is used as coarse and fine aggregate, although the prepared concrete has certain ray shielding performance, the natural high-density aggregate is much higher than cement slurry in volume density, so the natural high-density aggregate is easy to settle and separate in concrete vibration construction, and the construction operability is poor; secondly, the radiation-proof concrete prepared from the natural high-density aggregate is generally low in strength due to the characteristics of large density and generally low strength of the natural high-density aggregate, and is mainly used for non-bearing members; thirdly, the natural ores with high density and radiation-proof property have limited reserves, cannot meet the increasing engineering requirements and are not suitable for being used in large quantities.
Disclosure of Invention
The invention aims to provide a radiation-proof functional aggregate prepared by using electroplating sludge containing Cr and Zn, which has excellent radiation-proof performance and mechanical property, can replace the traditional natural high-density ore aggregate, solves the problem of a weak ray shielding area caused by poor homogeneity of the traditional radiation-proof concrete, can consume a large amount of industrial sludge containing heavy metals, and has important economic and environmental benefits.
In order to achieve the purpose, the invention adopts the technical scheme that:
an anti-radiation functional aggregate prepared by using electroplating sludge containing Cr and Zn comprises a regenerated aggregate and a cement paste shell layer coated on the surface of the regenerated aggregate; the recycled aggregate is prepared by sintering the following components in percentage by mass: 49-56% of electroplating sludge powder, 25-33% of shale, 14-22% of metakaolin and 1-4% of fluxing agent; the cement paste shell layer is formed by mixing and curing the following components in percentage by mass: 62-69% of cement, 8.3-12.4% of silica fume, 5.3-8.8% of an expanding agent, 12.5-16.0% of water and 1.4-2.0% of a water reducing agent.
According to the scheme, the electroplating sludge powder is prepared by air-drying electroplating sludge containing heavy metals of Cr and Zn discharged by electroplating industry, wherein Cr is2O3The mass content of the ZnO is more than or equal to 25 percent, the mass content of the ZnO is more than or equal to 15 percent, and the water content is less than or equal to 4 percent.
According to the scheme, the shale is particles with the particle size of less than or equal to 4.75mm after the shale is mined and crushed, wherein SiO is2Mass content of not less than 55%, Al2O3The mass content is more than or equal to 20 percent, and the ignition loss is less than or equal to 10 percent.
According to the scheme, the specific surface area of the metakaolin is more than or equal to 15000m2/kg，SiO2Has a mass content of not less than 40% and Al2O3The mass content of the compound is more than or equal to 30 percent.
According to the scheme, the preparation method of the fluxing agent comprises the following steps: 1) dissolving borax in water at 95-100 ℃, and filtering to obtain a clear solution; 2) dropwise adding a sulfuric acid solution with the mass concentration of 10-20% into the obtained clear solution under the stirring condition until crystals are separated out, then controlling the dropwise adding speed of the sulfuric acid solution to ensure that the pH value of the obtained mixed solution is maintained at 4-5, and after the crystals are completely separated out, sequentially filtering and drying at the temperature of 60-70 ℃ for 1.5-2 hours to obtain boric acid crystals; 3) heating the obtained boric acid crystal to 300-400 ℃ under a vacuum condition, calcining for 0.5-1 h, then heating to 500-600 ℃ and calcining for 1-2 h, finally heating to 800-900 ℃ and preserving heat for 1-2 h, and naturally cooling to obtain a glass state B2O3A crystal; 4) glass is prepared byState B2O3Crystals, Na2O、K2Mixing O uniformly, preheating for 0.5-1 h at 500-600 ℃, then preserving heat for 2-3 h at 1120-1180 ℃, and finally obtaining B through water quenching and quenching2O3-Na2O-K2O eutectic, said glassy state B2O3Crystals, Na2O、K2The mass percentage of O is as follows: glass state B2O3Crystal 40-50%, Na2O 25～35％、K215-25% of O; 5) b is to be2O3-Na2O-K2And grinding the O eutectic substance to obtain the cosolvent.
In the scheme, the ratio of the mass of the boric acid to the volume of water in the step 1) is 1 (1.6-2.8) g: ml.
In the scheme, the vacuum condition in the step 3) is that the vacuum degree is less than or equal to 300 Pa.
According to the scheme, the cement is P.O 42.5.5 or P.O 52.5.5 ordinary portland cement.
According to the scheme, the specific surface area of the silica fume is more than or equal to 17000m2/kg，SiO2The mass content of the active substance is more than or equal to 85 percent, and the 28d activity index is more than or equal to 104 percent.
According to the scheme, the expanding agent is MgO type expanding agent, and the specific surface area is more than or equal to 200m2/kg。
According to the scheme, the water reducing agent is a common polycarboxylic acid type water reducing agent, the solid content is more than or equal to 50%, and the water reducing rate is more than or equal to 25%.
According to the scheme, the water is common tap water.
According to the scheme, the sintering process of the reclaimed aggregate comprises the following steps: 1) weighing the components according to the mixture ratio, wherein the mass percent of each component is as follows: 49-56% of electroplating sludge powder, 25-33% of shale, 14-22% of metakaolin and 1-4% of fluxing agent; mixing and grinding the weighed raw materials, and then granulating, wherein the particle size is 5-10 mm, and the water content is 16-20%; 2) preheating the balls obtained by granulation at 500-600 ℃ for 30-40 min, calcining at 1020-1080 ℃ for 40-50 min, and naturally cooling in air to room temperature to obtain the regenerated aggregate.
The preparation method of the radiation-proof functional aggregate comprises the following steps: 1) weighing the components of the cement paste according to the following mixture ratio, wherein the mass percentage of each component is as follows: 62-69% of cement, 8.3-12.4% of silica fume, 5.3-8.8% of an expanding agent, 12.5-16.0% of water and 1.4-2.0% of a water reducing agent, dry-mixing the regenerated aggregate with the weighed cement, silica fume and the expanding agent for 2-4 min under a vacuum condition, adding water and the water reducing agent, continuously stirring for 5-10 min under a vacuum state, uniformly spreading the obtained regenerated aggregate wrapping a cement paste shell layer, avoiding the occurrence of cementation among the aggregates, and naturally curing for 1-2 d; 2) curing the product obtained in the step 1) for 4-6 h at 180-200 ℃ under 1-2 MPa, and cooling to room temperature to obtain the radiation-proof functional aggregate prepared by using the electroplating sludge containing Cr and Zn.
In the scheme, the mass ratio of the regenerated aggregate to the cement paste is 1 (0.25-0.55).
In the scheme, the vacuum condition in the step 1) is 2 kPa-5 kPa.
In the scheme, the coating thickness of the cement paste shell layer is 0.5-1.0 mm.
The invention adopts the following principle:
(1) aggregate radiation protection performance: industrial waste (electroplating sludge) containing heavy metal elements such as Cr, Zn and the like in the electroplating industry is selected as an aggregate sintering raw material, wherein the Cr, Zn heavy metal element atomic nucleus, extra-nuclear electrons and gamma rays generate complex material effects (mainly comprising photoelectric effect, Compton scattering and electron pair effect); when gamma rays pass through the absorption material, gamma photons can generate a material effect with atomic nuclei in an internal atomic structure of the material and extra-nuclear electrons, and the ray intensity is attenuated, so that the obtained regenerated aggregate shows radiation protection performance.
(2) Fluxing agent: the invention reduces the sintering temperature of the aggregate by adding the fluxing agent, avoids the loss of heavy metal ions and further obtains the regenerated aggregate with higher content of Cr and Zn heavy metal ions. The concrete mechanism is that Al is generated in the process of sintering the aggregate2O3、SiO2A refractory component which determines the firing temperature of the aggregate. B in flux2O3、Na2O、K2O is reacted at high temperature, wherein B, Na, K and other ions can react with Al2O3、SiO2Forming a low melting point solid solution; can enter SiO simultaneously2In the Si-O tetrahedral structure of (A), the original tetrahedral structure is changed and is no longer completely tightly connected, and free oxygen is decomposed, resulting in SiO2The stability of the product is reduced, and the sintering temperature is lowered (the sintering temperature can be lowered by 130-150 ℃). Effectively avoiding the dissolution or volatilization of heavy metal ions.
(3) Sintering the regenerated aggregate: selecting electroplating industrial sludge containing heavy metal elements Cr and Zn, and correcting Si and Al minerals by shale and metakaolin to ensure that the base material of the regenerated aggregate mainly contains the elements of Si, Al, Cr and Zn; at this time, a large amount of Al is contained in the shale and metakaolin2O3、SiO2As a refractory component, provides strength for the aggregate in the calcining process, prevents the regenerated aggregate from collapsing in the calcining process, and forms a compact core structure; meanwhile, the heavy metal elements of Cr and Zn are fused and combined with the mineral phases of Si and Al in the shale and the metakaolin to be dissolved in Al in a solid solution manner2O3、SiO2In the formed solid solution, a stable mineral phase is formed, so that the dissolution of heavy metals in the sintering process is avoided, and the ray shielding performance of the functional aggregate is improved.
(4) Coating the surface of the regenerated aggregate: the invention adopts the cement slurry surface strengthening treatment process, can effectively make up surface defects (holes, microcracks and the like) which are easily generated by the sintered regenerated aggregate, improve the properties of the aggregate such as strength, durability and the like, can improve the apparent density of the aggregate, and solves the problem of poor working performance of concrete mixtures caused by small density of common artificial aggregates; meanwhile, the vacuum stirring process (the vacuum degree is 2 kPa-5 kPa) is adopted, so that bubbles can be prevented from being introduced into the gelled slurry during stirring, and the pores in the slurry are only from water evaporation, so that the porosity of the gelled slurry is reduced, and the compactness and the strength of the gelled slurry are improved; in addition, the vacuum stirring can make the cement paste more easily enter the pores and microcracks on the surface of the regenerated aggregate, improve the interface transition layer between the regenerated aggregate and the cement paste and further improve the compactness of the aggregate with the radiation-proof function(ii) a At the same time, a certain quantity of MgO type expanding agent is added to make it active under the condition of steam pressure, and the hydration product Mg (OH)2The slurry pores are filled and are inserted among the hydrated gelled slurry, so that the shrinkage resistance is increased, the slurry is subjected to a shrinkage compensation effect, and an interface transition layer between the slurry and the sintered aggregate is improved, so that the strength and the radiation resistance of the obtained functional aggregate are improved.
(5) Steam pressure curing: the invention adopts the autoclaved curing process to improve the hydration degree of cement and the pozzolan reaction degree between the cement and the silica fume, fully stimulate the activity of MgO type expanding agent, and increase the gelled slurry C-S-H gel and Ca (OH)2、Mg(OH)2The quantity of the hydration products is equal, so that the pore structure of the gelled slurry is improved; meanwhile, the autoclaved condition can promote the conversion of high alkalinity C-S-H to zeolite products such as tobermorite and the like with good crystallinity, so that the structure of a hydration product is more stable, and the solidification effect of heavy metal ions is enhanced from the physical angle; the regenerated aggregate is subjected to slurry wrapping treatment and then autoclaved and maintained, so that the strength of the aggregate is improved, the interface transition layer between gelled slurry and the aggregate is greatly improved, the solidification effect of the aggregate on heavy metal ions is improved, the service life of the aggregate is prolonged, and the reduction of the radiation resistance of concrete caused by the dissolution of the heavy metal ions in the service process is avoided.
Compared with the prior art, the invention has the beneficial effects that:
(1) the electroplating sludge containing heavy metal elements Cr and Zn is fired into the regenerated aggregate for the radiation-proof concrete, so that the treatment problem of the industrial waste sludge is solved, the environment is protected, the traditional natural high-density ore aggregate can be replaced, and the problem of a ray shielding weak area caused by poor homogeneity of the traditional radiation-proof concrete is solved.
(2) Using electroplating sludge powder as main raw material, and utilizing SiO in shale and metakaolin2、Al2O3Provides strength for the aggregate, and is assisted with a certain firing system to dissolve Cr and Zn heavy metal ions in a Si/Al phase solid solution, so that the radiation protection performance and the strength of the regenerated aggregate are greatly improved.
(3) Using B in flux2O3、Na2O、K2The component O can effectively reduce the firing temperature, not only avoids the dissolution of heavy metal ions, but also meets the requirements of the national energy development strategy.
(4) The high-strength cement paste is utilized to carry out pre-wrapping treatment on the recycled aggregate, the surface structure of the recycled aggregate is optimized, the porosity of the aggregate is reduced, the compactness of the aggregate is improved, the mechanical property and the radiation protection performance of the aggregate are increased, the problem that the density of the common artificial aggregate is small is solved, and the density of the aggregate is equivalent to that of concrete mixture mortar, so that the homogeneity of radiation protection concrete is improved.
(5) The expanding agent is applied to the preparation of the high-strength cement paste, the activity of the high-strength cement paste is excited by combining an autoclaved curing process, and the volume shrinkage generated in the hydration process of the gelled slurry is compensated by utilizing the expansion characteristic of MgO, so that the problem of the interface defect between the slurry and the aggregate is solved, and the compactness and the strength of the synthesized aggregate are improved; and simultaneously, an autoclaved curing system is adopted to cure the pre-wrapped slurry aggregate, the slurry porosity is reduced, the strength of the slurry is increased, an interface transition layer between the cement slurry and the regenerated aggregate is improved, and the curing effect of the aggregate on heavy metal ions is enhanced by improving the microstructure composition of the cement slurry, so that the strength of the radiation-proof functional aggregate, the performances of ray shielding and the like and the curing effect of the heavy metal ions are improved.
The radiation-proof functional aggregate prepared by the invention has excellent performance indexes, and the apparent density is 2500kg/m3About, the compressive strength of single particle is more than or equal to 14.0MPa, and the linear failure coefficient is more than or equal to 0.24cm-1The high-strength radiation-proof concrete has good strength and radiation-proof performance and great practical application value, and can be used for preparing high-strength radiation-proof concrete.
Drawings
FIG. 1 is a schematic structural diagram of a gamma-ray shielding experimental apparatus used in embodiments 1 to 4.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the following examples, the electroplating sludge powder was obtained by air-drying industrial sludge (electroplating sludge) containing heavy metal elements of Cr and Zn from a surface treatment industry-related enterprise in the huzhou industrial park, and Cr was obtained2O326.68 percent of the total weight of the powder, 19.63 percent of the mass content of ZnO and 3.0 percent of water content; the shale is produced from a certain shale mine in Yichang city of Hubei province, the particle size is less than or equal to 4.75mm, wherein SiO is257.33% by mass of Al2O3The mass content of the catalyst is 24.14 percent, and the ignition loss is 8.2 percent; the metakaolin is provided by Hangzhou Chongke chemical engineering Co., Ltd, and has a specific surface area of 16000m2/kg，SiO242.89% by mass of Al2O334.15% by mass; the cement is Huaxin P.O 42.5 ordinary portland cement, and the specific surface area is 320m2Per kg; the silica fume is provided by Shanghai happy silicon powder materials, Inc., and has a specific surface area of 18000m2/kg，SiO2The mass content of (A) is 90%, and the 28d activity index is 105%; the expanding agent is MgO type expanding agent produced by Wuhan three-source special building materials GmbH, and has a specific surface area of 220m2Per kg; the water reducing agent is produced by Jiangsu Subot new material company Limited
Figure BDA0001177651880000051
The solid content of the type polycarboxylate superplasticizer is 50 percent, and the water reducing rate is 30 percent; the water is common tap water.
The preparation method of the fluxing agent comprises the following steps:
1) adding 550ml of distilled water into a magnetic stirring heating pot, heating to about 95 ℃, then adding 250g of borax, fully stirring until the borax is completely dissolved, ensuring the temperature of the mixed solution to be above 90 ℃, and simultaneously filtering the solution to obtain a clear solution; 2) dropwise adding dilute sulfuric acid with the mass concentration of 15% into the clear solution obtained in the step 1) by using an acid burette, slowly stirring until crystals are separated out, controlling the adding speed of the sulfuric acid at the moment, ensuring that the pH value of the solution is maintained at 4-5, filtering the residual solution after the crystals are completely separated out, and drying at the temperature of 65 ℃ for 1.5 hours to obtain boric acid crystals; 3) prepared by the step 2)Heating the obtained boric acid crystal to 350 ℃ under vacuum (260Pa), calcining for 0.5h, then heating to 600 ℃ and calcining for 1h, finally preserving the heat at 800 ℃ for 2h, and naturally cooling to obtain a glass state B2O3A crystal; 4) the glassy state B prepared in the step 3)2O3Crystals with Na2O、K2Mixing O, preheating at 550 deg.C for 1 hr, maintaining at 1160 deg.C for 3 hr, quenching with water to obtain B2O3-Na2O-K2O eutectic, wherein the mass percent of each component is as follows: glass state B2O3Crystal 45% and Na2O 30％、K2O25 percent; 5) b prepared in the step 4)2O3-Na2O-K2And fully grinding the O eutectic substance, and sieving by a 70-mesh sieve to obtain the fluxing agent.
Examples 1 to 4
The radiation-proof aggregate prepared by using the Cr and Zn-containing electroplating sludge in the embodiments 1 to 4 comprises a regenerated aggregate and a cement paste shell layer coated on the surface of the regenerated aggregate; the regenerated aggregate is formed by sintering electroplating sludge powder, shale, metakaolin and a fluxing agent; the cement paste shell is prepared by mixing and curing cement, silica fume, an expanding agent, water and a water reducing agent which are used as raw materials, and the specific proportion is shown in table 1; the preparation method comprises the following steps:
1) weighing the components for aggregate sintering according to the proportion shown in Table 1, mixing and grinding the weighed raw materials, and then granulating to obtain granules with the particle size of 5-10 mm and the water content of 18%; 2) preheating the balls obtained by granulation at 550 ℃ for 35min, calcining at 1060 ℃ for 50min, and finally naturally cooling to room temperature in the air to obtain regenerated aggregates; 3) weighing the components of the cement paste for surface coating according to the proportion in the table 1, dry-mixing 100kg of regenerated aggregate with the weighed cement, silica fume and expanding agent in a vacuum stirring pot (vacuum degree 4kPa) for 2min, adding water and water reducing agent, continuously stirring for 8min in a vacuum state, uniformly spreading the obtained regenerated aggregate coated with the cement paste to avoid cementation among aggregates, and naturally curing for 1 d; 4) curing the product obtained in the step 3) at 200 ℃ and 2MPa for 6h, and cooling to room temperature to obtain the radiation-proof functional aggregate prepared by using the electroplating sludge containing Cr and Zn.
In order to verify whether the heavy metal elements Cr and Zn exist stably in the service process of the radiation-proof functional aggregate obtained in the embodiment 1-4, the toxic leaching amount of the heavy metal elements in the corrosion solution of the radiation-proof functional aggregate fragments is tested according to the standard HJ/T299-2007 sulfuric acid-nitric acid method for leaching toxicity of solid waste.
In order to verify whether the radiation-proof functional aggregate obtained in the embodiments 1 to 4 has good radiation-proof performance, a 0.662MeV gamma ray shielding experiment (the structural schematic diagram is shown in fig. 1) is performed on the aggregate, and the experimental device mainly comprises: radioactive source isotope gamma ray source, NaI (T1) probe and digital gamma energy spectrometer. Placing a test sample between the detector and the radioactive source, and performing 60s timed ray intensity measurement; measuring the thickness of the sample by using a vernier caliper; and calculating the linear attenuation coefficient of the material by using a least square method.
The performance test results of the radiation-proof functional aggregate prepared in the examples 1 to 4 are shown in Table 2.
TABLE 1 addition amount (kg) of raw materials of the radiation-proof functional aggregate described in examples 1 to 4
Figure BDA0001177651880000061
Table 2 each performance index of the radiation-proof functional aggregate prepared in examples 1 to 4
Figure BDA0001177651880000071
The results show that the apparent density of the radiation-proof aggregate prepared by using the electroplating sludge containing Cr and Zn is 2500kg/m3About, far below the apparent density of barite (4200-4600 kg/m)3) The density of the slurry of the concrete mixture is closer to that of the slurry of the concrete mixture, and the slurry can be more uniformly distributed in the radiation-proof concrete, so that the concrete has better homogeneity, the interface performance between the obtained functional aggregate and the set cement is enhanced, and the volume weight of the radiation-proof concrete is reduced; the linear attenuation coefficient is higher than 0.24cm-1And barite (mu 0.24-0.27 cm)-1) Close; the single-particle compressive strength is more than or equal to 14.0MPa (the barite is about 12 MPa); the leaching concentration of the heavy metal meets the national standard requirements of GB5080.3-2007 identification standard for hazardous waste-leaching toxicity identification and GB 5080.3-1996 integrated wastewater discharge standard.
The foregoing examples are provided merely for the purpose of clearly illustrating the present invention and are not intended to be limiting of the embodiments, nor are all embodiments necessarily exhaustive. It will be apparent to those skilled in the art that several modifications and variations can be made without departing from the inventive concept herein.

Claims (9)

1. The radiation-proof functional aggregate prepared by using the electroplating sludge containing Cr and Zn is characterized by comprising regenerated aggregate and a cement paste shell layer coated on the surface of the regenerated aggregate; the recycled aggregate is prepared by sintering the following components in percentage by mass: 49-56% of electroplating sludge powder, 25-33% of shale, 14-22% of metakaolin and 1-4% of fluxing agent; the cement paste shell layer is formed by mixing and curing the following components in percentage by mass: 62-69% of cement, 8.3-12.4% of silica fume, 5.3-8.8% of an expanding agent, 12.5-16.0% of water and 1.4-2.0% of a water reducing agent;
the sintering process of the recycled aggregate comprises the following steps: 1) weighing the components according to the mixture ratio, wherein the mass percent of each component is as follows: 49-56% of electroplating sludge powder, 25-33% of shale, 14-22% of metakaolin and 1-4% of fluxing agent; mixing and grinding the weighed raw materials, and then granulating, wherein the particle size is 5-10 mm, and the water content is 16-20%; 2) preheating the balls obtained by granulation at 500-600 ℃ for 30-40 min, calcining at 1020-1080 ℃ for 40-50 min, and naturally cooling in air to room temperature to obtain the regenerated aggregate.
2. The radiation-proof functional aggregate according to claim 1, wherein the electroplating sludge powder is prepared by air-drying electroplating sludge containing heavy metals of Cr and Zn discharged from electroplating industry, wherein Cr is2O3The mass content of the ZnO is more than or equal to 25 percent, the mass content of the ZnO is more than or equal to 15 percent, and the water content is less than or equal to 4 percent.
3. The radiation-proof functional aggregate according to claim 1, wherein the shale is granules with the particle size of less than or equal to 4.75mm after shale mining and crushing, wherein SiO is2Mass content of not less than 55%, Al2O3The mass content is more than or equal to 20 percent, and the ignition loss is less than or equal to 10 percent.
4. The radiation-proof functional aggregate according to claim 1, wherein the metakaolin has a specific surface area of 15000m or more2/kg，SiO2Has a mass content of not less than 40% and Al2O3The mass content of the compound is more than or equal to 30 percent.
5. The radiation-proof functional aggregate according to claim 1, wherein the preparation method of the fluxing agent is as follows: 1) dissolving borax in water at 95-100 ℃, and filtering to obtain a clear solution; 2) dropwise adding a sulfuric acid solution with the mass concentration of 10-20% into the obtained clear solution under the stirring condition until crystals are separated out, then controlling the dropwise adding speed of the sulfuric acid solution to ensure that the pH value of the obtained mixed solution is maintained at 4-5, and after the crystals are completely separated out, sequentially filtering and drying at the temperature of 60-70 ℃ for 1.5-2 hours to obtain boric acid crystals; 3) heating the obtained boric acid crystal to 300-400 ℃ under a vacuum condition, calcining for 0.5-1 h, then heating to 500-600 ℃ and calcining for 1-2 h, finally heating to 800-900 ℃ and preserving heat for 1-2 h, and naturally cooling to obtain a glass state B2O3A crystal; 4) a glass state B2O3Crystals, Na2O、K2Mixing O uniformly, preheating for 0.5-1 h at 500-600 ℃, then preserving heat for 2-3 h at 1120-1180 ℃, and finally obtaining B through water quenching and quenching2O3-Na2O-K2O eutectic, said glassy state B2O3Crystals, Na2O、K2The mass percentage of O is as follows: glass state B2O3Crystal 40-50%, Na2O 25～35％、K2O15-25%; 5) b is to be2O3-Na2O-K2And grinding the O eutectic to obtain the fluxing agent.
6. The radiation-proof functional aggregate according to claim 1, wherein the specific surface area of the silica fume is not less than 17000m2/kg，SiO2The mass content of the active substance is more than or equal to 85 percent, and the 28d activity index is more than or equal to 104 percent.
7. The radiation-proof functional aggregate according to claim 1, wherein the swelling agent is MgO type swelling agent, and the specific surface area is not less than 200m2/kg。
8. The preparation method of the radiation-proof functional aggregate of any one of claims 1 to 7, which is characterized by comprising the following steps: 1) weighing the components of the cement paste according to the following mixture ratio, wherein the mass percentage of each component is as follows: 62-69% of cement, 8.3-12.4% of silica fume, 5.3-8.8% of an expanding agent, 12.5-16.0% of water and 1.4-2.0% of a water reducing agent, dry-mixing the regenerated aggregate with the weighed cement, silica fume and the expanding agent for 2-4 min under a vacuum condition, adding water and the water reducing agent, continuously stirring for 5-10 min under a vacuum state, uniformly spreading the obtained regenerated aggregate coated with cement paste, avoiding cementation among the aggregates, and naturally curing for 1-2 d; 2) curing the product obtained in the step 1) for 4-6 h at 180-200 ℃ under 1-2 MPa, and cooling to room temperature to obtain the radiation-proof functional aggregate prepared by using the electroplating sludge containing Cr and Zn.
9. The production method according to claim 8, wherein the vacuum condition in the step 1) is 2kPa to 5 kPa.
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