CN114853373A - Method for solidifying/stabilizing heavy metal chromium in chromium slag - Google Patents
Method for solidifying/stabilizing heavy metal chromium in chromium slag Download PDFInfo
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- CN114853373A CN114853373A CN202210535296.1A CN202210535296A CN114853373A CN 114853373 A CN114853373 A CN 114853373A CN 202210535296 A CN202210535296 A CN 202210535296A CN 114853373 A CN114853373 A CN 114853373A
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- 239000002893 slag Substances 0.000 title claims abstract description 176
- 239000011651 chromium Substances 0.000 title claims abstract description 166
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 title claims abstract description 165
- 229910052804 chromium Inorganic materials 0.000 title claims abstract description 165
- 229910001385 heavy metal Inorganic materials 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 34
- 230000000087 stabilizing effect Effects 0.000 title claims abstract description 26
- 239000002131 composite material Substances 0.000 claims abstract description 47
- 238000001035 drying Methods 0.000 claims abstract description 38
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 claims abstract description 30
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 28
- 239000012190 activator Substances 0.000 claims abstract description 27
- 238000003756 stirring Methods 0.000 claims abstract description 20
- 238000002156 mixing Methods 0.000 claims abstract description 16
- 229960005070 ascorbic acid Drugs 0.000 claims abstract description 15
- 235000010323 ascorbic acid Nutrition 0.000 claims abstract description 15
- 239000011668 ascorbic acid Substances 0.000 claims abstract description 15
- 238000000498 ball milling Methods 0.000 claims abstract description 10
- 238000011049 filling Methods 0.000 claims abstract description 8
- 239000002245 particle Substances 0.000 claims abstract description 8
- 238000007873 sieving Methods 0.000 claims abstract description 8
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 21
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 13
- 239000007787 solid Substances 0.000 claims description 12
- 235000019353 potassium silicate Nutrition 0.000 claims description 11
- 239000002994 raw material Substances 0.000 claims description 4
- 239000003795 chemical substances by application Substances 0.000 claims description 3
- 150000001875 compounds Chemical class 0.000 claims 1
- 238000002386 leaching Methods 0.000 abstract description 36
- 239000000463 material Substances 0.000 abstract description 18
- 230000008569 process Effects 0.000 abstract description 8
- 239000002699 waste material Substances 0.000 abstract description 8
- 238000002360 preparation method Methods 0.000 abstract description 5
- 239000002910 solid waste Substances 0.000 abstract description 5
- 230000007613 environmental effect Effects 0.000 abstract description 3
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 29
- 239000008367 deionised water Substances 0.000 description 15
- 229910021641 deionized water Inorganic materials 0.000 description 15
- 239000003513 alkali Substances 0.000 description 12
- 229920000876 geopolymer Polymers 0.000 description 10
- 238000007711 solidification Methods 0.000 description 10
- 230000008023 solidification Effects 0.000 description 9
- 230000006641 stabilisation Effects 0.000 description 7
- 238000011105 stabilization Methods 0.000 description 7
- 238000011957 budget and coverage analysis Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 239000003638 chemical reducing agent Substances 0.000 description 5
- 230000001988 toxicity Effects 0.000 description 5
- 231100000419 toxicity Toxicity 0.000 description 5
- 238000005303 weighing Methods 0.000 description 5
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 4
- 238000011160 research Methods 0.000 description 4
- 239000005995 Aluminium silicate Substances 0.000 description 3
- 229910021536 Zeolite Inorganic materials 0.000 description 3
- 235000012211 aluminium silicate Nutrition 0.000 description 3
- 229910052793 cadmium Inorganic materials 0.000 description 3
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 3
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 239000010457 zeolite Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 239000011398 Portland cement Substances 0.000 description 2
- 239000004115 Sodium Silicate Substances 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000010881 fly ash Substances 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 229910052911 sodium silicate Inorganic materials 0.000 description 2
- 238000004846 x-ray emission Methods 0.000 description 2
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000002920 hazardous waste Substances 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- ZODDGFAZWTZOSI-UHFFFAOYSA-N nitric acid;sulfuric acid Chemical compound O[N+]([O-])=O.OS(O)(=O)=O ZODDGFAZWTZOSI-UHFFFAOYSA-N 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000037361 pathway Effects 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 231100000820 toxicity test Toxicity 0.000 description 1
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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
-
- 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
- C04B7/14—Cements containing slag
- C04B7/147—Metallurgical slag
- C04B7/153—Mixtures thereof with other inorganic cementitious materials or other activators
- C04B7/1535—Mixtures thereof with other inorganic cementitious materials or other activators with alkali metal containing activators, e.g. sodium hydroxide or waterglass
-
- 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
- C04B7/364—Avoiding environmental pollution during cement-manufacturing
-
- 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)
- Inorganic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biodiversity & Conservation Biology (AREA)
- Ecology (AREA)
- Environmental & Geological Engineering (AREA)
- Environmental Sciences (AREA)
- Public Health (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention discloses a method for solidifying/stabilizing heavy metal chromium in chromium slag, which comprises the following steps of (1) drying the chromium slag, adding ascorbic acid after drying, adding water for stirring, and drying the chromium slag to obtain detoxified chromium slag; (2) drying the blast furnace slag, performing ball milling treatment after drying, and sieving to obtain the blast furnace slag with uniform particle size; (3) adding water into the composite excitant to prepare a composite excitant solution, uniformly mixing the blast furnace slag and the detoxified chromium slag, adding the composite excitant solution, uniformly stirring, and then performing mould filling, curing, demoulding and curing; the composite activator comprises, by mass, 10-50 parts of chromium slag, 45-81 parts of blast furnace slag and 5-9 parts of composite activator. The preparation method is simple to operate, the prepared cementing material has excellent mechanical properties, the environmental problem caused by the stockpiling of industrial solid wastes such as blast furnace slag and the like can be reduced, the leaching of heavy metal chromium in the chromium slag can be effectively cured, and the purpose of treating wastes with processes of wastes against one another is achieved.
Description
Technical Field
The invention relates to a curing/stabilizing method, in particular to a curing/stabilizing method for heavy metal chromium in chromium slag.
Background
Solidification/stabilization techniques are considered to be an efficient method of disposing hazardous waste. Meanwhile, the alkali-activated cementing material is an ideal material applied to the curing/stabilizing process. Compared with Ordinary Portland Cement (OPC), this material generally has several advantages: 1) the carbon dioxide emission is low; 2) energy is saved; 3) good chemical corrosion resistance; 4) effectively solidify heavy metal ions. Compared with metakaolin, fly ash and other materials, the blast furnace slag has higher sulfur content and can be used as a reducing agent of hexavalent chromium in the process of solidifying chromium slag. In addition, according to the existing studies, the compressive strength of alkali slag cement is generally higher than that of geopolymers.
The cementing material is used for the curing/stabilizing treatment process of heavy metal chromium and chromium-containing pollutants by a plurality of researchers at home and abroad, so that the problem of stockpiling of industrial solid wastes can be solved, the aim of treating wastes with wastes can be fulfilled, and the cementing material achieves two purposes in a real sense.
El-Esewed et al investigated the solidification efficiency and mechanism of kaolin/zeolite based geopolymers for the heavy metals Pb (II), Cu (II), Cd (II) and Cr (III). And (3) researching the in-out behavior of heavy metals in geopolymers in different leaching solutions by measuring the leaching amount, the pH value and the conductivity of the heavy metals in the leaching solution. The results of the studies show that kaolin/zeolite based geopolymers effectively solidify several of the above mentioned heavy metals by releasing safe metal ions such as Na + and K +. The solidification of heavy metals in geopolymers by leaching experiments, conductivity and X-ray fluorescence spectroscopy (XRF) analysis is due to the participation of heavy metal cations in the negative charge balance of aluminum in the framework of unreacted zeolite, kaolin and geopolymer phases. Furthermore, in combination with the mechanical properties and XRD analysis of the geopolymer, it was not affected by heavy metal incorporation, so there was no evidence that heavy metals were involved in a new pathway for geopolymerization.
The Weochou utilizes the composite geopolymer to carry out curing/stabilizing treatment on the chromium slag, compares the curing effects of three composite geopolymers of slag-metakaolin, fly ash-metakaolin and slag-fly ash-metakaolin and common portland cement on the chromium slag, and finds that the curing effect of the slag-fly ash-metakaolin system composite geopolymer on the chromium slag is optimal; by combining FTIR, NMR, SEM-EDS, XPS, XRD and other technical analysis means, the gelled material is proved to realize solidification/stabilization treatment of hexavalent chromium and trivalent chromium in chromium slag mainly through three modes of chemical combination, physical adsorption and physical solid sealing.
Zhang et al have conducted relatively deep research on alkali-activated blast furnace slag solidification/stabilization treatment of hexavalent chromium by studying factors such as sodium hydroxide mixing amount, liquid-solid ratio, initial hexavalent chromium content, maintenance duration and the like, and research results show that: the alkali-activated blast furnace slag material has higher compressive strength and can effectively physically wrap hexavalent chromium; the total chromium leaching concentration of the 1.5 percent hexavalent chromium-doped solidified body 180d is lower than the limit value of 5mg/L in the TCLP leaching standard; the alkali-activated blast furnace slag cementing material has strong capability of reducing hexavalent chromium into trivalent chromium.
Muhammad et al, which uses sodium silicate and sodium hydroxide as a composite alkali activator to excite blast furnace slag and fly ash to prepare a cementing material, and correspondingly studies the solidification/stabilization of heavy metals such as hexavalent chromium, lead, cadmium and the like. The solidification/stabilization effect of the polycarboxylic acid water reducer on hexavalent chromium, lead and cadmium is researched by researching the influence of four factors such as the addition amount of the polycarboxylic acid water reducer, the proportion of an alkali activator, the liquid-solid ratio, the curing temperature and the like on the mechanical property of the alkali-activated cementing material and combining the leaching results of a horizontal oscillation method and a sulfuric acid-nitric acid method. The result shows that after curing at 70 ℃, the proper water reducing agent improves the mechanical property of the gelled body by reducing the liquid-solid ratio; when the addition amounts of hexavalent chromium, lead and cadmium are 0.1%, 0.5% and 0.3%, respectively, the leaching toxicity of the solidified body is lower than the corresponding limit in GB 5085.3-2007.
In summary, the main disadvantages of the prior art solutions are as follows:
(1) the related raw materials are more, and the pretreatment is more complicated;
(2) the use amount of the alkali activator is large, so that the disposal cost is high;
(3) the compressive strength of the cured product was 20MPa or more, but still low.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a method for solidifying/stabilizing heavy metal chromium in chromium slag, which has the advantages of simple pretreatment process, low production cost and high compressive strength.
The technical scheme is as follows: the invention uses the composite alkali activator (sodium hydroxide and sodium silicate) to excite the industrial solid waste blast furnace slag to prepare the alkali-excited cementing material with excellent performance, and uses the material to realize the detoxification-solidification/stabilization treatment of the chromium slag by combining with ascorbic acid. The preparation method is simple to operate, the prepared cementing material has excellent mechanical properties, the environmental problem caused by the stockpiling of industrial solid wastes such as blast furnace slag and the like can be reduced, the leaching of heavy metal chromium in the chromium slag can be effectively cured, and the purpose of treating wastes with processes of wastes against one another is realized.
The invention relates to a method for solidifying/stabilizing heavy metal chromium in chromium slag, which comprises the following steps:
(1) drying the chromium slag, adding ascorbic acid after drying, adding water for stirring, and drying the chromium slag to obtain detoxified chromium slag;
(2) drying the blast furnace slag, performing ball milling treatment after drying, and sieving to obtain the blast furnace slag with uniform particle size and larger specific surface area;
(3) adding water into the composite excitant to prepare a composite excitant solution, uniformly mixing the blast furnace slag and the detoxified chromium slag, adding the composite excitant solution, uniformly stirring, and then performing mould filling, curing, demoulding and curing; the composite activator comprises, by mass, 10-50 parts of chromium slag, 45-81 parts of blast furnace slag and 5-9 parts of composite activator.
Further, in the step (1), the drying temperature is 100-105 ℃, and the drying time is 6-8 hours; the mass ratio of the ascorbic acid to the chromium slag is 0.7-1%; the mass ratio of the water to the chromium slag is 1: 1-1.5: 1, and the stirring time is 20-30 min.
Further, in the step (2), the drying temperature is 100-105 ℃, and the drying time is 4-6 hours; the ball milling time is 8-12 h.
Further, the mass ratio of the water to the solid raw materials (the composite exciting agent, the chromium slag and the blast furnace slag) in the step (3) is 0.24-0.26; the stirring time is 10-15 min; the composite excitant is prepared by mixing sodium hydroxide and water glass, and the modulus of the water glass is 1.6-1.8.
Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: (1) the preparation process is simple. The blast furnace slag can be used for preparing the alkali-activated cementing material with excellent performance under the action of the composite activator (sodium hydroxide and water glass), the chromium slag is jointly treated by combining with ascorbic acid, the effective solidification of heavy metal chromium in the chromium slag can be realized, the process is simple, the waste is treated by waste, and the problem of industrial waste residue accumulation is solved; (2) low leaching toxicity and low leaching rate of hexavalent chromium. The ascorbic acid and the alkali-activated cementing material realize the curing/stabilizing treatment of the chromium slag mainly through chemical reduction, chemical combination and physical sealing. The addition of the ascorbic acid greatly reduces the leaching risk of hexavalent chromium in the chromium slag, so that the leaching concentration of hexavalent chromium in the solidified body is obviously reduced. The method has large curing amount of the chromium slag, low leaching toxicity and low leaching rate of hexavalent chromium; (3) the prepared gelled polymer has excellent mechanical property, wherein the compressive strength of the prepared solidified body can reach 124MPa at most, and the parts of chromium slag, blast furnace slag and composite excitant are 10 parts; 50 parts of chromium slag, 45 parts of blast furnace slag and 5 parts of composite excitant, the strength of a cured body can still reach 55MPa, and the curing effect on the chromium slag is better.
Drawings
FIG. 1 is a flow chart of the solidification/stabilization process of heavy metal chromium in chromium slag;
FIG. 2 is a graph showing the compressive strength of a solidified body of chromium slag;
FIG. 3 is a leaching toxicity curve diagram of hexavalent chromium in the chromium slag solidified body;
FIG. 4 is a graph showing the leaching rate of hexavalent chromium from the solidified chromium slag.
Detailed Description
The technical scheme of the invention is further explained by combining the attached drawings.
Example 1
The method for solidifying/stabilizing the heavy metal chromium in the chromium slag comprises the following steps:
(1) drying the chromium slag in an oven at 105 ℃ for about 6 hours, weighing the dried chromium slag, adding 0.7% of ascorbic acid (in mass ratio to the chromium slag), adding deionized water according to the mass ratio of the chromium slag to the deionized water of 1:1, stirring for about 20min, and drying the chromium slag to obtain detoxified chromium slag;
(2) drying blast furnace slag in an oven at 105 ℃ for about 6 hours, then ball-milling, and sieving by a 200-mesh sieve to obtain uniform particle size and larger specific surface area;
(3) adding deionized water into a composite activator (the composite activator is prepared by mixing sodium hydroxide and water glass) at a liquid-solid ratio of 0.24 to prepare a composite activator solution, uniformly mixing blast furnace slag and detoxified chromium slag, adding the composite activator solution, uniformly stirring, and then performing mold filling, curing, demolding and curing (the curing temperature is set to 25 ℃ in the initial 24 hours); according to the mass parts, the chromium slag is 10 parts, the blast furnace slag is 81 parts, and the composite excitant is 9 parts (the modulus of water glass is 1.6). The obtained solidified body of the chromium slag is marked as BCA 10.
Example 2
The method for solidifying/stabilizing the heavy metal chromium in the chromium slag comprises the following steps:
(1) drying the chromium slag in an oven at 105 ℃ for about 6 hours, weighing the dried chromium slag, adding 0.7% of ascorbic acid (in mass ratio to the chromium slag), adding deionized water according to the mass ratio of the chromium slag to the deionized water of 1:1, stirring for about 20min, and drying the chromium slag to obtain detoxified chromium slag;
(2) drying blast furnace slag in an oven at 105 ℃ for about 6 hours, then ball-milling, and sieving by a 200-mesh sieve to obtain uniform particle size and larger specific surface area;
(3) adding deionized water into the composite activator at a liquid-solid ratio of 0.24 to prepare a composite activator solution, uniformly mixing blast furnace slag and detoxified chromium slag, adding the composite activator solution, uniformly stirring, and then performing mold filling, curing, demolding and curing (the curing temperature is set to 25 ℃ in the initial 24 h); according to the mass parts, the chromium slag is 20 parts, the blast furnace slag is 72 parts, and the composite excitant is 8 parts (the modulus of water glass is 1.6). The obtained solidified body of the chromium slag is marked as BCA 20.
Example 3
The method for solidifying/stabilizing the heavy metal chromium in the chromium slag comprises the following steps:
(1) drying the chromium slag in an oven at 105 ℃ for about 6 hours, weighing the dried chromium slag, adding 0.7% of ascorbic acid (in mass ratio to the chromium slag), adding deionized water according to the mass ratio of the chromium slag to the deionized water of 1:1, stirring for about 20min, and drying the chromium slag to obtain detoxified chromium slag;
(2) drying blast furnace slag in an oven at 105 ℃ for about 6 hours, then ball-milling, and sieving by a 200-mesh sieve to obtain uniform particle size and larger specific surface area;
(3) adding deionized water into the composite activator at a liquid-solid ratio of 0.24 to prepare a composite activator solution, uniformly mixing blast furnace slag and detoxified chromium slag, adding the composite activator solution, uniformly stirring, and then performing mold filling, curing, demolding and curing (the curing temperature is set to 25 ℃ in the initial 24 h); according to the mass parts, the chromium slag is 30 parts, the blast furnace slag is 63 parts, and the composite excitant is 7 parts (the modulus of water glass is 1.6). The obtained solidified body of the chromium slag is marked as BCA 30.
Example 4
The method for solidifying/stabilizing the heavy metal chromium in the chromium slag comprises the following steps:
(1) drying the chromium slag in an oven at 105 ℃ for about 6 hours, weighing the dried chromium slag, adding 0.7% of ascorbic acid (in mass ratio to the chromium slag), adding deionized water according to the mass ratio of the chromium slag to the deionized water of 1:1, stirring for about 20min, and drying the chromium slag to obtain detoxified chromium slag;
(2) drying blast furnace slag in an oven at 105 ℃ for about 6 hours, then ball-milling, and sieving by a 200-mesh sieve to obtain uniform particle size and larger specific surface area;
(3) adding deionized water into the composite activator at a liquid-solid ratio of 0.24 to prepare a composite activator solution, uniformly mixing blast furnace slag and detoxified chromium slag, adding the composite activator solution, uniformly stirring, and then performing mold filling, curing, demolding and curing (the curing temperature is set to 25 ℃ in the initial 24 h); the chromium slag comprises, by mass, 40 parts of chromium slag, 54 parts of blast furnace slag and 6 parts of composite excitant (the modulus of water glass is 1.6). The obtained solidified body of the chromium slag is marked as BCA 40.
Example 5
The method for solidifying/stabilizing the heavy metal chromium in the chromium slag comprises the following steps:
(1) drying the chromium slag in an oven at 105 ℃ for about 6 hours, weighing the dried chromium slag, adding 0.7% of ascorbic acid (in mass ratio to the chromium slag), adding deionized water according to the mass ratio of the chromium slag to the deionized water of 1:1, stirring for about 20min, and drying the chromium slag to obtain detoxified chromium slag;
(2) drying blast furnace slag in an oven at 105 ℃ for about 6 hours, then ball-milling, and sieving by a 200-mesh sieve to obtain uniform particle size and larger specific surface area;
(3) adding deionized water into the composite activator at a liquid-solid ratio of 0.24 to prepare a composite activator solution, uniformly mixing blast furnace slag and detoxified chromium slag, adding the composite activator solution, uniformly stirring, and then performing mold filling, curing, demolding and curing (the curing temperature is set to 25 ℃ in the initial 24 h); according to the mass parts, the chromium slag is 50 parts, the blast furnace slag is 45 parts, and the composite excitant is 5 parts (the modulus of water glass is 1.6). The obtained solidified body of the chromium slag is marked as BCA 50.
Examples 1-5 preparation of chromium slag solidified bodies the ingredients can be seen in Table 1, and the preparation flow diagram is shown in FIG. 1.
TABLE 1 compounding ingredients/part of chromium slag solidified body
Research on the compressive strength of the chromium slag solidified body:
the relationship between the compressive strength of the solidified chromium slag 28d and the amount of the chromium slag added can be seen in FIG. 2. As can be seen from the figure, the compressive strength (28d) of the solidified chromium slag body tends to decrease with an increase in the amount of the chromium slag (10 to 50 parts). When the mixing amount of the chromium slag is within 30 parts, the compressive strength of the solidified body is 124MPa, 121MPa and 104MPa respectively, and the compressive strength is more than 100 MPa; when the mixing amount of the chromium slag is continuously increased to 40 parts, the compressive strength of the solidified body is reduced to 90 MPa; when the mixing amount of the chromium slag is increased to 50 parts, the compressive strength of a solidified body of the chromium slag is reduced to 55 MPa.
The leaching toxicity research of the chromium slag solidified body comprises the following steps:
the relationship between the leaching concentration of hexavalent chromium in the chromium slag solidified body and the doping amount of chromium slag can be shown in FIG. 3. As can be seen from the figure, the leaching concentration of hexavalent chromium in the solidified chromium slag shows a gradually increasing trend (0.16-2.56 mu g/mL) along with the increase of the doping amount of the chromium slag, and the leaching concentration is far lower than the limit value of 5 mu g/mL in GB 5085.3-2007. The leaching concentrations of hexavalent chromium in the 20 parts and 30 parts of chromium slag doped solidified body are respectively 0.44 mu g/mL and 0.97 mu g/mL (0.44 mu g/mL <0.5 mu g/mL <0.97 mu g/mL), and referring to technical Specification for environmental protection for chromium slag pollution control (HJ/T301-2007), the leaching of hexavalent chromium in the solidified body when the chromium slag doping amount is within 20 parts (inclusive) can be known to meet the regulation limit value for being used as roadbed material and concrete aggregate; when the chromium slag is mixed in 50 parts, the leaching concentration of hexavalent chromium in the solidified body is 2.56 mu g/mL (<3 mu g/mL), and referring to HJ/T301-2007, the leaching of hexavalent chromium of the solidified body within 50 parts (including 50 parts) of the chromium slag can meet the requirements of general industrial solid waste landfills.
Calculating the leaching rate of hexavalent chromium:
leaching rate (L) of heavy metals i /(%)) is an important index for evaluating the curing effect, and the calculation formula is as follows:
C o ＝(m×W 1，i ×W 2 )/V (2)
wherein, C 0 The ion concentration (mg/L) of the solidified body when hexavalent chromium is leached out by 100 percent is shown; c i Is the measured hexavalent chromium leaching concentration (mg/L) of the solidified body in a leaching toxicity test; m is the mass (mg) of the cured body; w 1,i The content (%) of chromium slag in the solidified body; w 2 The content of hexavalent chromium in the chromium slag is (%); v is the volume of the leaching agent (L).
The leaching rate of hexavalent chromium in the chromium slag solidified body is correspondingly calculated by using the formulas (1) and (2), and the calculation result is shown in fig. 4. Wherein the BCAs 10-50 represent solidified bodies with the chromium slag mixing amount of 10-50 parts respectively.
As can be seen from the graph, the leaching rate of hexavalent chromium from the solidified chromium slag is concentrated on 2.0% to 8.5%, which is mainly benefited from the detoxifying effect of ascorbic acid. In addition, the leaching rate of hexavalent chromium in the chromium slag sample is calculated by the formulas (1) and (2), the leaching rate is up to 74.51%, and the solidified phase of the chromium slag is greatly reduced (> 78.0%). Therefore, the solidified body has a good solidifying/stabilizing effect on heavy metal chromium from the viewpoint of leaching rate.
Claims (9)
1. A method for solidifying/stabilizing heavy metal chromium in chromium slag is characterized by comprising the following steps:
(1) drying the chromium slag, adding ascorbic acid after drying, adding water for stirring, and drying the chromium slag to obtain detoxified chromium slag;
(2) drying the blast furnace slag, performing ball milling treatment after drying, and sieving to obtain the blast furnace slag with uniform particle size;
(3) adding water into the composite excitant to prepare a composite excitant solution, uniformly mixing the blast furnace slag and the detoxified chromium slag, adding the composite excitant solution, uniformly stirring, and then performing mould filling, curing, demoulding and curing; the composite activator comprises, by mass, 10-50 parts of chromium slag, 45-81 parts of blast furnace slag and 5-9 parts of composite activator.
2. The method for solidifying/stabilizing heavy metal chromium in chromium slag according to claim 1, wherein the drying temperature in step (1) is 100-105 ℃ and the drying time is 6-8 h.
3. A method for solidifying/stabilizing heavy metal chromium in chromium slag according to claim 1, wherein the ascorbic acid accounts for 0.7-1% by mass of the chromium slag in step (1).
4. The method for solidifying/stabilizing heavy metal chromium in chromium slag according to claim 1, wherein the mass ratio of the water to the chromium slag in the step (1) is 1: 1-1.5: 1, and the stirring time is 20-30 min.
5. The method for solidifying/stabilizing heavy metal chromium in chromium slag according to claim 1, wherein the drying temperature in step (2) is 100-105 ℃ and the drying time is 4-6 h.
6. The method for solidifying/stabilizing heavy metal chromium in chromium slag according to claim 1, wherein the ball milling time in step (2) is 8-12 h.
7. A method for solidifying/stabilizing heavy metal chromium in chromium slag according to claim 1, wherein the mass ratio of the water to the solid raw materials in step (3) is 0.24-0.26, and the solid raw materials are composite exciting agent, chromium slag and blast furnace slag.
8. A method for solidifying/stabilizing heavy metal chromium in chromium slag according to claim 1, wherein the stirring time in step (3) is 10-15 min.
9. The method for solidifying/stabilizing heavy metal chromium in chromium slag according to claim 1, wherein the compound excitant in the step (3) is prepared by mixing sodium hydroxide and water glass, and the modulus of the water glass is 1.6-1.8.
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