CN106947487B - Modifier for composite heavy metal polluted soil and preparation and use methods thereof - Google Patents
Modifier for composite heavy metal polluted soil and preparation and use methods thereof Download PDFInfo
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- CN106947487B CN106947487B CN201710243108.7A CN201710243108A CN106947487B CN 106947487 B CN106947487 B CN 106947487B CN 201710243108 A CN201710243108 A CN 201710243108A CN 106947487 B CN106947487 B CN 106947487B
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- 239000002689 soil Substances 0.000 title claims abstract description 153
- 229910001385 heavy metal Inorganic materials 0.000 title claims abstract description 130
- 238000000034 method Methods 0.000 title claims abstract description 68
- 239000003607 modifier Substances 0.000 title claims abstract description 56
- 239000002131 composite material Substances 0.000 title claims abstract description 42
- 238000002360 preparation method Methods 0.000 title claims abstract description 9
- 239000000843 powder Substances 0.000 claims abstract description 117
- 239000002893 slag Substances 0.000 claims abstract description 92
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 75
- 239000010959 steel Substances 0.000 claims abstract description 75
- 229910019142 PO4 Inorganic materials 0.000 claims abstract description 54
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims abstract description 53
- 239000010452 phosphate Substances 0.000 claims abstract description 53
- 229910000389 calcium phosphate Inorganic materials 0.000 claims abstract description 45
- 239000000463 material Substances 0.000 claims abstract description 36
- YYRMJZQKEFZXMX-UHFFFAOYSA-L calcium bis(dihydrogenphosphate) Chemical compound [Ca+2].OP(O)([O-])=O.OP(O)([O-])=O YYRMJZQKEFZXMX-UHFFFAOYSA-L 0.000 claims abstract description 35
- 235000019691 monocalcium phosphate Nutrition 0.000 claims abstract description 35
- 239000000047 product Substances 0.000 claims description 54
- 239000000203 mixture Substances 0.000 claims description 48
- 238000007873 sieving Methods 0.000 claims description 42
- 238000003756 stirring Methods 0.000 claims description 39
- 238000001035 drying Methods 0.000 claims description 35
- 238000000227 grinding Methods 0.000 claims description 34
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 33
- 239000003610 charcoal Substances 0.000 claims description 32
- 238000002156 mixing Methods 0.000 claims description 28
- 239000002245 particle Substances 0.000 claims description 27
- 239000003795 chemical substances by application Substances 0.000 claims description 24
- 239000002244 precipitate Substances 0.000 claims description 21
- 239000003814 drug Substances 0.000 claims description 12
- 241001122767 Theaceae Species 0.000 claims description 11
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 10
- 238000001354 calcination Methods 0.000 claims description 10
- 239000001506 calcium phosphate Substances 0.000 claims description 10
- 235000011010 calcium phosphates Nutrition 0.000 claims description 10
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 claims description 10
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 claims description 9
- 238000007885 magnetic separation Methods 0.000 claims description 9
- 238000002791 soaking Methods 0.000 claims description 9
- 229910052802 copper Inorganic materials 0.000 claims description 7
- 239000010949 copper Substances 0.000 claims description 7
- 229910052759 nickel Inorganic materials 0.000 claims description 7
- 229910052725 zinc Inorganic materials 0.000 claims description 7
- 239000011701 zinc Substances 0.000 claims description 7
- 230000003647 oxidation Effects 0.000 claims description 4
- 238000007254 oxidation reaction Methods 0.000 claims description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 3
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 3
- 239000006260 foam Substances 0.000 claims description 2
- 238000013329 compounding Methods 0.000 claims 2
- 230000000694 effects Effects 0.000 abstract description 16
- 238000002386 leaching Methods 0.000 abstract description 15
- 230000007613 environmental effect Effects 0.000 abstract description 8
- 238000011161 development Methods 0.000 abstract description 6
- 230000008901 benefit Effects 0.000 abstract description 5
- 230000006641 stabilisation Effects 0.000 abstract description 5
- 238000011105 stabilization Methods 0.000 abstract description 5
- 239000003344 environmental pollutant Substances 0.000 abstract description 4
- 230000005012 migration Effects 0.000 abstract description 4
- 238000013508 migration Methods 0.000 abstract description 4
- 231100000719 pollutant Toxicity 0.000 abstract description 4
- 231100000331 toxic Toxicity 0.000 abstract description 4
- 230000002588 toxic effect Effects 0.000 abstract description 4
- 239000002253 acid Substances 0.000 abstract description 3
- 239000002994 raw material Substances 0.000 abstract description 2
- 229910000402 monopotassium phosphate Inorganic materials 0.000 description 21
- 235000019796 monopotassium phosphate Nutrition 0.000 description 21
- 238000012360 testing method Methods 0.000 description 21
- PJNZPQUBCPKICU-UHFFFAOYSA-N phosphoric acid;potassium Chemical compound [K].OP(O)(O)=O PJNZPQUBCPKICU-UHFFFAOYSA-N 0.000 description 20
- 239000000243 solution Substances 0.000 description 19
- 230000000052 comparative effect Effects 0.000 description 15
- 238000005067 remediation Methods 0.000 description 11
- 229910052751 metal Inorganic materials 0.000 description 9
- 239000002184 metal Substances 0.000 description 9
- 231100000419 toxicity Toxicity 0.000 description 9
- 230000001988 toxicity Effects 0.000 description 9
- 238000005336 cracking Methods 0.000 description 8
- 230000035784 germination Effects 0.000 description 8
- 238000007711 solidification Methods 0.000 description 8
- 230000008023 solidification Effects 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 230000004913 activation Effects 0.000 description 7
- 229910052799 carbon Inorganic materials 0.000 description 7
- 238000011065 in-situ storage Methods 0.000 description 7
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 6
- 239000011133 lead Substances 0.000 description 6
- 241000196324 Embryophyta Species 0.000 description 5
- 235000010469 Glycine max Nutrition 0.000 description 5
- 244000068988 Glycine max Species 0.000 description 5
- 230000018109 developmental process Effects 0.000 description 5
- 229910052588 hydroxylapatite Inorganic materials 0.000 description 5
- XYJRXVWERLGGKC-UHFFFAOYSA-D pentacalcium;hydroxide;triphosphate Chemical compound [OH-].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O XYJRXVWERLGGKC-UHFFFAOYSA-D 0.000 description 5
- 230000000087 stabilizing effect Effects 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 238000005303 weighing Methods 0.000 description 5
- 230000009471 action Effects 0.000 description 4
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 4
- 229910052745 lead Inorganic materials 0.000 description 4
- 239000002910 solid waste Substances 0.000 description 4
- 239000001569 carbon dioxide Substances 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 3
- 239000004568 cement Substances 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 230000003628 erosive effect Effects 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 3
- 150000002894 organic compounds Chemical class 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000008439 repair process Effects 0.000 description 3
- 230000007226 seed germination Effects 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 235000011941 Tilia x europaea Nutrition 0.000 description 2
- 238000003916 acid precipitation Methods 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 230000003213 activating effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 239000000292 calcium oxide Substances 0.000 description 2
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 239000002920 hazardous waste Substances 0.000 description 2
- 230000036571 hydration Effects 0.000 description 2
- 238000006703 hydration reaction Methods 0.000 description 2
- 239000004571 lime Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- ZODDGFAZWTZOSI-UHFFFAOYSA-N nitric acid;sulfuric acid Chemical compound O[N+]([O-])=O.OS(O)(=O)=O ZODDGFAZWTZOSI-UHFFFAOYSA-N 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000003900 soil pollution Methods 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 231100000674 Phytotoxicity Toxicity 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 239000007853 buffer solution Substances 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- YYRMJZQKEFZXMX-UHFFFAOYSA-N calcium;phosphoric acid Chemical compound [Ca+2].OP(O)(O)=O.OP(O)(O)=O YYRMJZQKEFZXMX-UHFFFAOYSA-N 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000010791 domestic waste Substances 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 239000005431 greenhouse gas Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 230000008635 plant growth Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- GNSKLFRGEWLPPA-UHFFFAOYSA-M potassium dihydrogen phosphate Chemical compound [K+].OP(O)([O-])=O GNSKLFRGEWLPPA-UHFFFAOYSA-M 0.000 description 1
- LWIHDJKSTIGBAC-UHFFFAOYSA-K potassium phosphate Substances [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 description 1
- 238000004382 potting Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000009331 sowing Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 239000002426 superphosphate Substances 0.000 description 1
- 239000002352 surface water Substances 0.000 description 1
- 231100000027 toxicology Toxicity 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K17/00—Soil-conditioning materials or soil-stabilising materials
- C09K17/02—Soil-conditioning materials or soil-stabilising materials containing inorganic compounds only
- C09K17/08—Aluminium compounds, e.g. aluminium hydroxide
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/08—Reclamation of contaminated soil chemically
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K2109/00—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE pH regulation
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Soil Sciences (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Inorganic Chemistry (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention discloses a modifier for composite heavy metal contaminated soil and a preparation and use method thereof, wherein the modifier comprises the following materials in percentage by mass: 30-55% of steel slag powder; 20-50% of calcium superphosphate powder; 5-30% of phosphate-loaded biochar. The invention has the advantages that: firstly, the modifier can obviously reduce the heavy metal migration and toxic leaching amount in heavy metal polluted soil, is especially suitable for acid polluted sites with high heavy metal content and more pollutant types, can be used as an environment-friendly material for resource utilization after polluted soil is repaired, and obviously reduces the environmental risk in secondary development and utilization of the polluted sites; meanwhile, the modifier has the advantages of easily available raw materials, low cost, simple preparation, convenient use and stable effect, and can be popularized and applied to curing stabilization restoration of a composite polluted site on a large scale.
Description
Technical Field
The invention relates to the field of environmental geotechnical engineering, in particular to a modifier for composite heavy metal polluted soil and a preparation and use method thereof.
Background
With the adjustment of urban functions and urban layout in China, enterprises in the central area and suburban areas of a city, such as chemical plants, metal smelting plants, electroplating plants and the like, are gradually shut down or move back to the city and enter the garden, but in the production process of the industry and the enterprises for many years, a large amount of pollutants are accumulated in the remaining land after the enterprises move, so that resistance is brought to the efficient utilization of the remaining land, and serious potential safety hazards are brought to the surrounding environment. In recent years, the action plan for preventing and treating soil pollution (ten items of soil) issued by the government also considers the remediation work of the polluted soil as one of the currently important civil engineering, and the development of the relevant remediation work of the pollution is urgent.
The heavy metal pollution of the soil in the industrial polluted site is characterized by multiple heavy metal species, high content, large acidity and the like. In the remediation of heavy metal contaminated sites, a solidification stabilization technique is widely adopted. The commonly used modifying agent mainly comprises materials such as cement, lime, phosphate and the like, has good effect on the solidification and stabilization of heavy metals, but also has a great deal of defects, such as large energy consumption for producing cement, more greenhouse gas emission and the like; lime and phosphate are non-renewable natural minerals, and the cost is high; moreover, the application of a large amount of phosphate can seriously change the soil structure and further cause phosphorus pollution of underground water and surface water.
In conclusion, the conventional modifying agent has many defects, and needs to reduce the use of cement and phosphate materials, and find a novel modifying agent which can cure and stabilize heavy metals, and has the advantages of high curing and stabilizing efficiency, low cost, stable performance, wide material sources and environmental friendliness, and thus becomes the focus of attention of environmental protection science and technology workers.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a modifier for composite heavy metal polluted soil, which can obviously reduce the migration and toxic leaching amount of heavy metals in the heavy metal polluted soil; the second purpose of the invention is to provide a preparation method of the heavy metal polluted soil modifier; the third purpose of the invention is to provide a using method of the heavy metal contaminated soil improving agent.
The technical scheme is as follows: the invention relates to a modifier for composite heavy metal polluted soil, which consists of the following materials in percentage by mass: 30-55% of steel slag powder; 20-50% of calcium superphosphate powder; 5-30% of phosphate-loaded biochar.
The composition materials of the modifier are preferably as follows: 35-50% of steel slag powder; 25-45% of calcium superphosphate powder; 10-25% of phosphate-loaded biochar.
The steel slag powder is activated steel slag powder prepared by the following method:
(1) one or more of the high-activity steel slag such as the converter slag, the open-hearth slag, the electric furnace oxidizing slag and the like after magnetic separation are crushed and sieved;
(2) drying the material with the particle size of less than 2mm in the obtained product until the water content is less than 2%, preferably drying by adopting airflow at 100-105 ℃;
(3) grinding the obtained product, sieving the product with a sieve of 150-200 meshes (for example, ball milling can be adopted), and calcining the product at the temperature of 500-700 ℃ for 1-2h (for example, electric furnace calcination can be preferably adopted, so that the method is energy-saving and practical), thereby obtaining the activated steel slag powder.
The phosphate-loaded biochar is prepared by the following method:
(1) preparing phosphate solution with concentration of 0.01-0.05mol/L (the phosphate is preferably monopotassium phosphate, the water solution is acidic, and the activating effect on the steel slag is better), and grinding the biochar through a 0.1-0.3mm sieve to obtain biochar powder;
(2) mixing the charcoal powder and aluminum sulfate according to the mass ratio of 20-30:1 to obtain a charcoal powder mixture;
(3) soaking the obtained charcoal powder mixture into phosphate solution, stirring for 10-15min (until the mixture is uniform), oscillating and stirring for 10-15h at 20-30 ℃, standing for 36-48h to obtain gelatinous precipitate, wherein the stirring purposes of the two times are different, the first stirring is to ensure that solid and liquid are in full contact, and the second stirring is to quickly generate gelatinous precipitate;
(4) and drying the gel-like precipitate by adopting 100-250 ℃ airflow until the water content is less than 2%, grinding the obtained product and sieving the product by using a 150-200-mesh sieve to obtain the phosphate-loaded biochar, wherein the airflow drying is quick, the medicament is not easy to agglomerate, and the subsequent medicament production is convenient.
One or more of the coffee residues, the tea powder and the traditional Chinese medicine residues are dried at the temperature of 100-105 ℃ until the mass of the one or more of the coffee residues, the tea powder and the traditional Chinese medicine residues is constant, and then the one or more of the coffee residues, the tea powder and the traditional Chinese medicine residues are cracked at the temperature of 400-700 ℃ under the anoxic condition to prepare the biochar.
The calcium superphosphate powder is prepared by the following method: will P2O5The calcium superphosphate with the content of 14-20 percent is dried by airflow at the temperature of 100 ℃ and 250 ℃ until the water content is less than 2 percent, and is ground and sieved by a sieve with 200 meshes at 150 ℃.
The preparation method of the modifier suitable for the composite heavy metal polluted soil comprises the following steps: mixing the steel slag powder, the calcium phosphate powder and the phosphate-loaded charcoal according to the weight percentage, stirring for 0.5-1h by a dry method until the mixture is uniform, and then sieving by a sieve of 150 meshes and 200 meshes to obtain the modifying agent.
The use method of the modifier suitable for the composite heavy metal polluted soil comprises the following steps: and mixing and stirring the modifying agent and the heavy metal polluted soil, wherein the dosage of the modifying agent is 5-15% of the dry weight of the heavy metal polluted soil, and the water content of the heavy metal polluted soil is 16-30%.
The content of particles with the particle diameter of less than 0.075mm in the heavy metal polluted soil is 65-100%, wherein the content of heavy metal lead is more than 2000mg/kg, the content of heavy metal zinc is more than 2000mg/kg, the content of heavy metal copper is more than 2000mg/kg, and the content of heavy metal nickel is more than 2000 mg/kg.
Has the advantages that: compared with the prior art, the invention has the remarkable advantages that:
(1) the heavy metal curing effect is good. Firstly, the steel slag related in the invention has an adsorption effect on heavy metal ions; secondly, the agricultural calcium superphosphate contains part of calcium sulfate, the potential gelling property of the steel slag is shown under the excitation action of the calcium sulfate, the phosphate precipitation and the hydroxide precipitation of heavy metals are effectively wrapped, and the solidification effect of the heavy metals only using phosphate is greatly enhanced; thirdly, the calcium oxide dissolved from the steel slag is hydrated to generate Ca (OH)2While the main component of the superphosphate is Ca (H)2PO4)2And the two react in an aqueous solution environment to generate a large amount of hydroxyapatite crystals. The hydroxyapatite can efficiently adsorb and complex heavy metals such as Pb, Zn, Cu, Ni and the like, the solubility of the hydroxyapatite and the heavy metal salt generated by the heavy metals is dozens of orders of magnitude lower than that of the hydroxyapatite heavy metal salt, and meanwhile, the hydroxyapatite is lower in dissolution under acidic and alkaline conditions, and the curing effect is better and more stable.
(2) The durability is good. The traditional modifier is easily affected by carbon dioxide erosion and acid rain erosion, and the phenomena of deterioration and attenuation of environmental safety and engineering characteristics of solidified polluted soil are generated. The modifier can effectively overcome the defects, because the generated heavy metal phosphate precipitates are agglomerated around the biochar, the solubility of the biochar is low in various pH environments, and the contact between the heavy metal precipitates and an acidic solution can be effectively reduced under the wrapping effect of a hydration product C-S-H gel of the steel slag; meanwhile, the steel slag has strong acid buffer capacity and carbon dioxide absorption capacity, and CaCO is generated under the action of carbon dioxide erosion3The crystal further fills the pores of the solidified body, effectively reduces the infiltration amount of the acid solution, and further increases the solidified bodyStability in harsh environments; in addition, the phosphate-loaded charcoal also has a good buffering effect on acid rain erosion, and the loaded phosphate can effectively inhibit the desorption effect of adsorbed heavy metals, so that the durability of the solidified body is further improved.
(3) Effectively utilizes waste raw materials and is an environment-friendly modifying agent. Firstly, the steel slag is used as industrial waste slag and is piled in a large area, so that serious environmental pollution is caused, the utilization value of the steel slag is effectively improved through the activation of the steel slag, and waste materials are changed into valuable materials. Secondly, the steel slag is directly used as a high-alkalinity material in the solidification and stabilization of the heavy metal polluted soil, the pH value of the solidified soil is high, many problems can be brought to the later development and utilization of the land, the pH value of the solidified soil is effectively reduced while the solidification effect of the steel slag on the heavy metal is effectively increased through activation and modification, and the solidification and stabilization effect of the steel slag on the heavy metal is optimal through the addition of calcium superphosphate. And thirdly, the coffee slag, the tea powder and the Chinese medicine slag are also domestic waste slag, and are further modified after being prepared into biochar through medium-high temperature cracking, so that the curing effect on metal can be effectively improved after the biochar is loaded with phosphate, the excitation on the steel slag can be realized, the hydration activity of the steel slag is improved, and the curing and stabilizing effect on heavy metal is improved.
Detailed Description
Example 1
The invention relates to a modifier suitable for composite heavy metal polluted soil, which consists of the following materials in parts by mass: 45% of steel slag powder; 35% of calcium superphosphate powder; 20% of phosphate-loaded biochar.
The steel slag powder is activated steel slag powder prepared by the following method: carrying out magnetic separation on the converter slag, and then crushing and sieving; placing the material with the particle size of less than 2mm in an oven to dry the material by adopting airflow at the temperature of 105 ℃ until the water content of the material is 1%; grinding the obtained product, sieving the ground product by a 200-mesh sieve, and calcining the product for 2 hours in an electric furnace at 700 ℃. The basicity value of the steel slag powder is 2.07.
The main components and contents of the steel slag are shown in table 1, and it should be noted that the steel slag suitable for the present invention is not limited to the data in table 1, and is only the steel slag used in the present embodiment:
TABLE 1 Steel slag main component and content
| Main chemical composition | CaO | SiO2 | Al2O3 | Fe2O3 | MgO | P2O5 |
| Content (%) | 36.30 | 16.26 | 3.32 | 18.66 | 8.35 | 1.26 |
The phosphate-loaded biochar is prepared by the following method: preparing a potassium dihydrogen phosphate solution with the concentration of 0.05mol/L, and grinding the biochar through a 0.2mm sieve to obtain biochar powder; fully mixing the charcoal powder and aluminum sulfate according to the mass ratio of 30:1 to obtain a charcoal powder mixture; soaking the obtained mixture into the obtained potassium dihydrogen phosphate solution, stirring for 15min until the mixture is uniformly mixed, oscillating and stirring for 15h at 25 ℃, and standing for 48h to obtain a gelatinous precipitate; and drying the gelatinous precipitate by adopting airflow at 200 ℃ until the water content is 1%, grinding the obtained product and sieving the ground product by using a 200-mesh sieve to obtain the biological carbon loaded with the potassium dihydrogen phosphate. The biochar is prepared by drying coffee grounds at 105 ℃ until the mass of the coffee grounds is not changed, and then cracking the coffee grounds for 6 hours at 600 ℃ under a closed anoxic condition, and the physical and chemical characteristics and the main chemical components of the biochar are shown in table 2.
TABLE 2 basic chemical Properties and essential element contents of biochar
The calcium superphosphate powder is prepared by the following method: will P2O5Drying 20% calcium superphosphate with 250 deg.C air flow until its water content is 1%, grinding and sieving with 200 mesh sieve.
The modifier suitable for the composite heavy metal polluted soil is prepared by the following steps: mixing the activated steel slag powder, the calcium phosphate powder and the phosphate-loaded charcoal in parts by mass, stirring for 1h by a dry method until the mixture is uniform, and sieving by a 200-mesh sieve to obtain the modifier.
The use method of the modifier suitable for the composite heavy metal polluted soil specifically comprises the following steps: and (3) mixing and stirring the modifying agent and the heavy metal polluted soil in situ, wherein the dosage of the modifying agent is 5% of the dry weight of the heavy metal polluted soil (accounting for the dry weight of the composite metal polluted soil). There are two types of heavy metal contaminants: the polluted soil a is lead and zinc composite polluted soil taken from an industrial polluted site; and the polluted soil b is copper and nickel composite polluted soil taken from two industrial polluted sites. Other major physicochemical properties are shown in table 3.
TABLE 3 main physicochemical Properties of contaminated soil
Example 2
The same procedure as in example 1 was followed except that the amount of the modifier was 10% (based on the dry weight of the soil contaminated with heavy metals and organic compounds).
Example 3
The same procedure as in example 1 was followed except that the amount of the modifier was 15% (based on the dry weight of the soil contaminated with heavy metals and organic compounds).
Comparative example 1
And (3) taking only the soil sample polluted by the compound heavy metal in the example 1 without adding any modifier.
Comparative example 2
The steel slag in the example 1 is used for preparing the modifier without activation, other preparation steps are unchanged, and the doping amount is 15 percent as in the example 3.
Example 4
The invention relates to a modifier suitable for composite heavy metal polluted soil, which consists of the following materials in parts by mass: 50% of steel slag powder; 25% of calcium superphosphate powder; 25% of phosphate-loaded biochar.
The steel slag powder is activated steel slag powder prepared by the following method: carrying out magnetic separation on the open hearth furnace slag, and then crushing and sieving; taking a material with the particle size of less than 2mm out of the obtained product, and drying the material by adopting airflow at the temperature of 100 ℃ until the water content of the material is 1.5%; grinding the obtained product, sieving the ground product by a sieve with 150 meshes, and calcining the product for 1h by an electric furnace at 500 ℃. The basicity value of the steel slag powder is 1.8.
The phosphate-loaded biochar is prepared by the following method: preparing a potassium dihydrogen phosphate solution with the concentration of 0.01mol/L, and grinding the biochar through a 0.1mm sieve to obtain biochar powder; fully mixing the charcoal powder and aluminum sulfate according to the mass ratio of 20:1 to obtain a charcoal powder mixture; soaking the obtained mixture into the obtained potassium dihydrogen phosphate solution, stirring for 10min until the mixture is uniformly mixed, oscillating and stirring for 10h at the temperature of 20 ℃, and standing for 36h to obtain a gelatinous precipitate; and drying the gelatinous precipitate by adopting airflow at 100 ℃ until the water content is 1.5%, grinding the obtained product and sieving the ground product by a 150-mesh sieve to obtain the biological carbon loaded with the potassium dihydrogen phosphate.
The biochar is prepared by drying coffee grounds at 100 ℃ until the quality of the coffee grounds is not changed, and cracking the coffee grounds at 400 ℃ under an anoxic condition.
The calcium superphosphate powder is prepared by the following method: will P2O5Drying the calcium superphosphate with the content of 14% by adopting airflow at 100 ℃ until the water content is 1.5%, and grinding and sieving by a 150-mesh sieve.
The modifier suitable for the composite heavy metal polluted soil is prepared by the following steps: and mixing the steel slag powder, the calcium phosphate powder and the phosphate-loaded charcoal in parts by mass, stirring for 0.5h by a dry method until the mixture is uniform, and sieving by a 150-mesh sieve to obtain the modifier.
The use method of the modifier suitable for the composite heavy metal polluted soil specifically comprises the following steps: and (2) mixing and stirring the modifying agent and the heavy metal polluted soil in situ, wherein the using amount of the modifying agent is 5% of the dry weight of the heavy metal polluted soil (accounting for the dry weight of the composite metal polluted soil), the water content of the heavy metal polluted soil is 16%, the heavy metal polluted soil is the same as the polluted soil selected in the embodiment 1, and the content of particles with the particle diameter of less than 0.075mm in the heavy metal polluted soil is 65%.
Example 5
The invention relates to a modifier suitable for composite heavy metal polluted soil, which consists of the following materials in parts by mass: 35% of steel slag powder; 45% of calcium superphosphate powder; 20% of phosphate-loaded biochar.
The steel slag powder is activated steel slag powder prepared by the following method: carrying out magnetic separation on the open hearth furnace slag, and then crushing and sieving; drying the material with the particle size of less than 2mm in the obtained product by adopting airflow at the temperature of 150 ℃ until the material is completely dried; grinding the obtained product, sieving the ground product by a 180-mesh sieve, and calcining the product for 1.5 hours at 600 ℃ by an electric furnace. The basicity value of the steel slag powder is 2.2.
The phosphate-loaded biochar is prepared by the following method: preparing a potassium dihydrogen phosphate solution with the concentration of 0.03mol/L by using phosphate, and grinding the biochar through a 0.3mm sieve to obtain biochar powder; fully mixing the charcoal powder and aluminum sulfate according to the mass ratio of 25:1 to obtain a charcoal powder mixture; soaking the obtained mixture in the obtained potassium dihydrogen phosphate solution, stirring for 13min until the mixture is uniformly mixed, oscillating and stirring for 12.5h at 25 ℃, and standing for 42h to obtain a gelatinous precipitate; and drying the gelatinous precipitate to be completely dry by adopting airflow at 180 ℃, grinding the obtained product and sieving the ground product by using a 170-mesh sieve to obtain the biological carbon loaded with the potassium dihydrogen phosphate.
The biochar is prepared by selecting tea leaves, drying the tea leaves at 102.5 ℃ until the quality of the tea leaves is not changed, and cracking the tea leaves at 550 ℃ under an anoxic condition.
The calcium superphosphate powder is prepared by the following method: will P2O5Baking 17% calcium superphosphate with 150 deg.C air flow to completely dry, grinding, and sieving with 170 mesh sieve.
The modifier suitable for the composite heavy metal polluted soil is prepared by the following steps: mixing the activated steel slag powder, the calcium phosphate powder and the phosphate-loaded charcoal in parts by mass, stirring for 0.75h by a dry method until the mixture is uniform, and sieving by a 170-mesh sieve.
The use method of the modifier suitable for the composite heavy metal polluted soil specifically comprises the following steps: and (2) mixing and stirring the modifying agent and the heavy metal polluted soil in situ, wherein the using amount of the modifying agent is 10% of the dry weight of the heavy metal polluted soil (accounting for the dry weight of the composite metal polluted soil), the water content of the heavy metal polluted soil is 23%, the heavy metal polluted soil is the same as the polluted soil selected in the embodiment 1, and the content of particles with the particle diameter of less than 0.075mm in the heavy metal polluted soil is 82.5%.
Example 6
The invention relates to a modifier suitable for composite heavy metal polluted soil, which consists of the following materials in parts by mass: 40% of steel slag powder; 50% of calcium superphosphate powder; 10% of phosphate-loaded biochar.
The steel slag powder is activated steel slag powder prepared by the following method: carrying out magnetic separation on the open hearth furnace slag, and then crushing and sieving; taking a material with the particle size of less than 2mm from the obtained product, and drying the material by adopting airflow at the temperature of 125 ℃ until the water content of the material is 0.5%; grinding the obtained product, sieving the ground product by a 200-mesh sieve, and calcining the product for 2 hours in an electric furnace at 700 ℃. The basicity value of the steel slag powder is 2.6.
The phosphate-loaded biochar is prepared by the following method: preparing a potassium dihydrogen phosphate solution with the concentration of 0.05mol/L, and grinding the biochar through a 0.2mm sieve to obtain biochar powder; fully mixing the charcoal powder and aluminum sulfate according to the mass ratio of 30:1 to obtain a charcoal powder mixture; soaking the obtained mixture into the obtained phosphate solution, stirring for 15min until the mixture is uniformly mixed, oscillating and stirring for 15h at 30 ℃, and standing for 48h to obtain a gelatinous precipitate; and drying the gelatinous precipitate by adopting airflow at 250 ℃ until the water content is 0.5%, grinding the obtained product, and sieving the ground product by using a 190-mesh sieve to obtain the biological carbon loaded with the potassium dihydrogen phosphate.
The biochar is prepared by drying the traditional Chinese medicine residues at 105 ℃ until the quality of the traditional Chinese medicine residues does not change any more, and then cracking the traditional Chinese medicine residues at 700 ℃ under an anoxic condition.
The calcium superphosphate powder is prepared by the following method: will P2O5Drying the calcium superphosphate with the content of 18% by adopting airflow at 180 ℃ until the water content is 0.5%, grinding and sieving by a 190-mesh sieve to obtain the calcium superphosphate powder.
The modifier suitable for the composite heavy metal polluted soil is prepared by the following steps: and mixing the steel slag powder, the calcium phosphate powder and the phosphate-loaded charcoal in parts by mass, stirring for 0.75h by a dry method until the mixture is uniform, and sieving by a 190-mesh sieve to obtain the modifier.
The use method of the modifier suitable for the composite heavy metal polluted soil specifically comprises the following steps: the modifying agent and the heavy metal polluted soil are mixed and stirred in situ. Wherein the dosage of the modifier is 15 percent of the dry weight of the heavy metal polluted soil (accounting for the dry weight of the composite metal polluted soil), and the water content of the heavy metal polluted soil is 30 percent. The content of particles with the particle size of less than 0.075mm in the used heavy metal contaminated soil is 83%, the heavy metal contaminated soil is the same as the contaminated soil selected in the embodiment 1, and the content of the particles with the particle size of less than 0.075mm in the heavy metal contaminated soil is 100%.
Example 7
The invention relates to a modifier suitable for composite heavy metal polluted soil, which consists of the following materials in parts by mass: 30% of steel slag powder; 40% of calcium superphosphate powder; 30% of phosphate-loaded biochar.
The steel slag powder is activated steel slag powder prepared by the following method: carrying out magnetic separation on the electric furnace oxidation slag, and then crushing and sieving; drying the material with the particle size of less than 2mm in the obtained product by adopting airflow at the temperature of 150 ℃ until the material is completely dried; grinding the obtained product, sieving the ground product by a 180-mesh sieve, and calcining the product for 1.5 hours at 600 ℃ by an electric furnace. The basicity value of the steel slag powder is 2.2.
The phosphate-loaded biochar is prepared by the following method: preparing a potassium dihydrogen phosphate solution with the concentration of 0.03mol/L by using phosphate, and grinding the biochar through a 0.3mm sieve to obtain biochar powder; fully mixing the charcoal powder and aluminum sulfate according to the mass ratio of 25:1 to obtain a charcoal powder mixture; soaking the obtained mixture in the obtained potassium dihydrogen phosphate solution, stirring for 13min until the mixture is uniformly mixed, oscillating and stirring for 12.5h at 25 ℃, and standing for 42h to obtain a gelatinous precipitate; and drying the gelatinous precipitate to be completely dry by adopting airflow at 180 ℃, grinding the obtained product and sieving the ground product by using a 200-mesh sieve to obtain the biological carbon loaded with the potassium dihydrogen phosphate.
The biochar is prepared by drying a mixture of tea leaf foam and coffee grounds at 102.5 ℃ until the mass of the mixture is not changed, and cracking the mixture at 600 ℃ under an anoxic condition.
The calcium superphosphate powder is prepared by the following method: will P2O5Drying the calcium superphosphate with the content of 18% by adopting airflow at 150 ℃ until the water content is 1%, grinding and sieving by a 200-mesh sieve.
The modifier suitable for the composite heavy metal polluted soil is prepared by the following steps: mixing the steel slag powder, the calcium phosphate powder and the phosphate-loaded charcoal in parts by mass, stirring for 0.75h by a dry method until the mixture is uniform, and sieving by a 200-mesh sieve.
The use method of the modifier suitable for the composite heavy metal polluted soil specifically comprises the following steps: and (2) mixing and stirring the modifying agent and the heavy metal polluted soil in situ, wherein the using amount of the modifying agent is 5% of the dry weight of the heavy metal polluted soil (accounting for the dry weight of the composite metal polluted soil), the water content of the heavy metal polluted soil is 25%, the heavy metal polluted soil is the same as the polluted soil selected in the embodiment 1, and the content of particles with the particle diameter of less than 0.075mm in the heavy metal polluted soil is 90%.
Example 8
The invention relates to a modifier suitable for composite heavy metal polluted soil, which consists of the following materials in parts by mass: 55% of steel slag powder; 20% of calcium superphosphate powder; 25% of phosphate-loaded biochar.
The steel slag powder is activated steel slag powder prepared by the following method: carrying out magnetic separation on the electric furnace oxidation slag, and then crushing and sieving; drying the material with the particle size of less than 2mm in the obtained product by adopting airflow at the temperature of 150 ℃ until the material is completely dried; grinding the obtained product, sieving the ground product by a 180-mesh sieve, and calcining the product for 1.5 hours at 600 ℃ by an electric furnace. The basicity value of the steel slag powder is 2.2.
The phosphate-loaded biochar is prepared by the following method: preparing a potassium dihydrogen phosphate solution with the concentration of 0.03mol/L by using phosphate, and grinding the biochar through a 0.3mm sieve to obtain biochar powder; fully mixing the charcoal powder and aluminum sulfate according to the mass ratio of 25:1 to obtain a charcoal powder mixture; soaking the obtained mixture in the obtained potassium dihydrogen phosphate solution, stirring for 13min until the mixture is uniformly mixed, oscillating and stirring for 12.5h at 25 ℃, and standing for 42h to obtain a gelatinous precipitate; and drying the gelatinous precipitate to be completely dry by adopting airflow at 180 ℃, grinding the obtained product and sieving the ground product by using a 200-mesh sieve to obtain the biological carbon loaded with the potassium dihydrogen phosphate.
The biochar is prepared by drying a mixture of coffee grounds and Chinese medicine residues at 102.5 ℃ until the mass of the mixture is not changed, and cracking the mixture at 450 ℃ under an anoxic condition.
The calcium superphosphate powder is prepared by the following method: will P2O5Drying the calcium superphosphate with the content of 18% by adopting airflow at 150 ℃ until the water content is 1%, grinding and sieving by a 200-mesh sieve to obtain the calcium superphosphate powder.
The modifier suitable for the composite heavy metal polluted soil is prepared by the following steps: mixing the steel slag powder, the calcium phosphate powder and the phosphate-loaded charcoal in parts by mass, stirring for 0.75h by a dry method until the mixture is uniform, and sieving by a 200-mesh sieve.
The use method of the modifier suitable for the composite heavy metal polluted soil specifically comprises the following steps: and (2) mixing and stirring the modifying agent and the heavy metal polluted soil in situ, wherein the using amount of the modifying agent is 10% of the dry weight of the heavy metal polluted soil (accounting for the dry weight of the composite metal polluted soil), the water content of the heavy metal polluted soil is 23%, the heavy metal polluted soil is the same as the polluted soil selected in the embodiment 1, and the content of particles with the particle diameter of less than 0.075mm in the heavy metal polluted soil is 75%.
Example 9
The invention relates to a modifier suitable for composite heavy metal polluted soil, which consists of the following materials in parts by mass: 55% of steel slag powder; 40% of calcium superphosphate powder; 5% of phosphate-loaded biochar.
The steel slag powder is activated steel slag powder prepared by the following method: carrying out magnetic separation on the electric furnace oxidation slag, and then crushing and sieving; drying the material with the particle size of less than 2mm in the obtained product by adopting airflow at the temperature of 150 ℃ until the material is completely dried; grinding the obtained product, sieving the ground product by a 180-mesh sieve, and calcining the product for 1.5 hours at 600 ℃ by an electric furnace. The basicity value of the steel slag powder is 2.2.
The phosphate-loaded biochar is prepared by the following method: preparing a potassium dihydrogen phosphate solution with the concentration of 0.03mol/L by using phosphate, and grinding the biochar through a 0.3mm sieve to obtain biochar powder; fully mixing the charcoal powder and aluminum sulfate according to the mass ratio of 25:1 to obtain a charcoal powder mixture; soaking the obtained mixture in the obtained potassium dihydrogen phosphate solution, stirring for 13min until the mixture is uniformly mixed, oscillating and stirring for 12.5h at 25 ℃, and standing for 42h to obtain a gelatinous precipitate; and drying the gelatinous precipitate to be completely dry by adopting airflow at 180 ℃, grinding the obtained product and sieving the ground product by using a 200-mesh sieve to obtain the biological carbon loaded with the potassium dihydrogen phosphate.
The biochar is prepared by selecting a mixture of tea leaf powder and Chinese medicine residues, drying the mixture at 102.5 ℃ until the mass of the mixture is not changed, and cracking the mixture at 550 ℃ under an anoxic condition.
The calcium superphosphate powder is prepared by the following method: will P2O5Drying the calcium superphosphate with the content of 18 percent by using airflow at 150 ℃ until the calcium superphosphate is hydratedThe percentage is 1 percent, and the calcium phosphate powder is obtained by grinding and sieving with a 200-mesh sieve.
The modifier suitable for the composite heavy metal polluted soil is prepared by the following steps: mixing the steel slag powder, the calcium phosphate powder and the phosphate-loaded charcoal in parts by mass, stirring for 0.75h by a dry method until the mixture is uniform, and sieving by a 200-mesh sieve.
The use method of the modifier suitable for the composite heavy metal polluted soil specifically comprises the following steps: mixing and stirring the modifying agent and the heavy metal polluted soil in situ, wherein the dosage of the modifying agent is 15% of the dry weight of the heavy metal polluted soil (accounting for the dry weight of the composite metal polluted soil), the water content of the heavy metal polluted soil is 23%, the heavy metal polluted soil is the same as the polluted soil selected in the embodiment 1, and the content of particles with the particle diameter of less than 0.075mm in the heavy metal polluted soil is 82.5%
Example 10
The sample soil after being implemented in example 1, example 2, example 3, comparative example 1, comparative example 2, example 4, example 5, example 6, example 7, example 8 and example 9 was tightly wrapped and sealed with a freshness protection package, and the toxicity leaching test was performed on the solidified contaminated soil after being cured for 28 days at 20 ℃ and a humidity of more than 95%:
test standards: the national environmental protection industry Standard sulfuric acid-nitric acid method for leaching toxicity of solid wastes (HJ/T299-2007).
The test process comprises the following steps: weighing 50g of the cured solidified polluted soil, drying at 105 ℃, and calculating to obtain the water content of the sample, wherein the error of the constant weight to the two weighing values is less than +/-1%. The dry weight of the remediation soil is calculated according to the water content, a remediation soil sample with the dry basis weight of 10g is weighed, and the test is carried out according to the method and the steps specified in the sulfuric acid-nitric method for leaching toxicity from solid waste (HJ/T299-2007). The test results are shown in table 4.
TABLE 4 toxicity Leaching test results (mg/L)
The sulfuric acid-nitric acid leaching method is used as a standard for evaluating whether solid waste is dangerous waste or not, and is a common method for analyzing the leaching toxicity characteristics of pollutants of the solid waste under the action of acid rainfall. From the toxicity leaching test results of Table 4, it can be seen by comparing examples 1-3, examples 4-6 and examples 7-9: according to the remediation soil doped with the modifier, the leaching concentrations of Zn, Pb, Ni and Cu in the leachate are reduced along with the increase of the doping amount of the modifier, the comparative example 1 shows that the heavy metal migration in the untreated source polluted soil is extremely strong, the leaching amounts of the heavy metals of Zn, Pb, Ni and Cu are far higher than the limit value in hazardous waste identification standard leaching toxicity identification (GB 5085.3-2007), and the addition of the modifier can be found to remarkably reduce the leaching amount of the heavy metals and increase the environmental safety by combining with the examples 1-9. As is clear from comparison between example 3 and comparative example 2, the stability of heavy metals was improved and the stabilizing effect in example 3 was more remarkable after 28 days of curing with the modifier of the present invention, the leaching amount is far lower than the limit value in the standard leaching toxicity identification of hazardous waste (GB 5085.3-2007), whereas the steel slag powder in the improver of comparative example 2 was formulated only from phosphate-loaded biochar without activation, which can reduce the migration characteristics of heavy metals Zn, Pb, Ni and Cu in soil to a certain extent, reduce the harm to the environmental safety and still meet the basic requirements of the invention, therefore, the activation modification treatment is carried out on the used steel slag, the solidification stabilizing effect of the modifier on heavy metal can be effectively enhanced, if the steel slag is not subjected to activation treatment, the technical effect of the invention can be realized to a certain extent.
Example 11
The soil remediation ph test was performed on the solidified contaminated soil after the curing in examples 1, 2, 3, 1, 2, 4, 5, 6, 7, 8 and 9 by the method of example 10:
test standards: method 4972-01 for pH of soil.
The test process comprises the following steps: weighing 50g of the cured solidified polluted soil, drying at 105 ℃, and calculating to obtain the water content of the sample, wherein the error of the constant weight to the two weighing values is less than +/-1%. And calculating the dry weight of the remediation soil according to the water content, sieving the remediation soil by using a 1mm sieve, weighing a remediation soil sample with the dry basis weight of 10g, stirring and mixing the remediation soil sample with 10g of distilled water, standing the mixture for 1h, and then testing the pH value of the solution. The test results are shown in table 5.
TABLE 5 PH value test results
The pH value of the solidified soil body is an important index for evaluating the effect of the modifier on solidifying heavy metal, and has great influence on the development mode and degree of secondary utilization of the restoration site. From the test results of the pH value in the table 5, as can be seen from the comparison between the examples 1 to 3 and the comparative example 1, after the modifier is added, the pH value of the solidified soil is significantly increased, after 28 days of maintenance, the pH value of the polluted soil is between 6 and 9 and is close to neutral, which is beneficial to the utilization of a repair site, meanwhile, the pH value of the solidified soil in the examples 4 to 9 is also significantly increased, and after 28 days of maintenance, the pH value of the polluted soil is between 6 and 9 and is close to neutral; compared with the example 3, the comparative example 2 has slightly higher pH value because the steel slag is not subjected to the activation treatment, but can basically realize the technical scheme of the invention, and if the pH value is continuously increased, a plurality of problems are brought to the later development and utilization of the land.
Example 12
Phytotoxicity tests (seed germination percentage tests) were performed on the soil cured in the method of example 10 of example 1, example 2, example 3, comparative example 1, comparative example 2, example 4, example 5, example 6, example 7, example 8 and example 9:
the test process comprises the following steps: the germination rate test of the seeds adopts soybeans which are sensitive to the content of heavy metal pollutants in soil, and the germination rate of the soybeans is used as an ecological index for carrying out toxicity analysis on the soil with heavy metal and organic compound pollution, so that the method is a commonly used important method for measuring the soil environment quality and the soil pollution from the ecological toxicology perspective. Firstly, the plain soil and the repair soil after 28 days of maintenance are naturally air-dried and sieved by a 2mm sieve for later use. Taking 4kg of soil (plain soil or each repair soil) for each sample, potting (the diameter of the upper opening is 25cm, the diameter of the bottom is 20cm, the height is 20cm), and the ridging height is 18 cm; the soil in the pot is thoroughly watered with distilled water until the water retention rate is 60 percent, and then the water retention rate is kept unchanged and the soil is soaked and placed indoors for 2 days; finally, soybean is sown, the soybean is sown at the depth of about 0.3cm, and 100 grains are sown in each pot; after sowing, the proper soil humidity is maintained by regularly spraying, so that the seeds germinate in the indoor sunny place at the room temperature of 18-22 ℃ under the condition of natural lighting. The germination rate (number of germinated seeds/number of test seeds) × 100%. The test results are shown in table 6.
Table 6 seed germination (%)
The seed germination rate test can reflect the toxic action of the soil to plants. As can be seen from table 6: the heavy metal content in the vegetarian soil (comparative example 1, namely the polluted soil without the modifier) is very high, the germination rate of the seeds is seriously influenced, and the germination rates of the soybean seeds in the polluted soil are only 8 percent and 12 percent. The modifier in the comparative example 2 improves the germination rate to a certain extent, but the improvement range is limited, and only the germination rates of 49% and 52% can be achieved, which shows that the modifier prepared by using the unactivated steel slag powder has a certain stabilizing effect on heavy metals in the polluted soil, and the effect is limited at that time; in contrast, the germination rates of the seeds of the modifier-restored soil in the embodiments 1 to 9 of the invention are all more than 85% under the condition of various blending amounts, and can even reach 99% to the maximum. The differences of the examples 1, 2 and 3 and the comparative example 1 show that the modifier disclosed by the invention is ecological and friendly in repairing the composite heavy metal contaminated soil, and is beneficial to the development and growth of plants and microorganisms around the repaired site, and the comparison of the example 3 and the comparative example 2 shows that the activating treatment on the steel slag can also effectively reduce the toxic action of the soil on the plants, so that the solidification stability of the steel slag on the heavy metals is reflected from the side surface.
Claims (8)
1. The modifier for the composite heavy metal polluted soil is characterized by comprising the following components in parts by weight: the material composition comprises the following materials in percentage by mass: 30-55% of steel slag powder; 20-50% of calcium superphosphate powder; 5-30% of phosphate-loaded charcoal;
the phosphate-loaded biochar is prepared by the following method:
(1) preparing phosphate solution with concentration of 0.01-0.05mol/L, grinding the biochar through a sieve with 0.1-0.3mm to obtain charcoal powder;
(2) mixing the charcoal powder and aluminum sulfate according to the mass ratio of 20-30:1 to obtain a charcoal powder mixture;
(3) soaking the obtained charcoal powder mixture in phosphate solution, stirring for 10-15min, shaking and stirring at 20-30 deg.C for 10-15 hr, and standing for 36-48 hr to obtain gel precipitate;
(4) and drying the gelatinous precipitate by adopting 100-250 ℃ airflow until the water content is less than 2%, grinding the obtained product, and sieving the ground product by using a 150-200-mesh sieve to obtain the phosphate-loaded biochar.
2. The improver for soil polluted by complex heavy metals according to claim 1, wherein: 35-50% of the steel slag powder; 25-45% of calcium superphosphate powder; 10-25% of phosphate-loaded biochar.
3. An improver for soil polluted by complex heavy metals according to claim 1 or 2, which is characterized in that: the steel slag powder is activated steel slag powder and is prepared by the following method:
(1) one or more of the converter slag, the open hearth furnace slag and the electric furnace oxidation slag after magnetic separation are crushed and sieved;
(2) drying the material with the particle size of less than 2mm in the obtained product until the water content is less than 2%;
(3) grinding the obtained product, sieving the product by a sieve with 150-200 meshes, and calcining the product for 1-2h at the temperature of 500-700 ℃ to obtain the activated steel slag powder.
4. The improver for soil polluted by complex heavy metals according to claim 1, wherein: the biochar is prepared by drying one or more of coffee grounds, tea foams and traditional Chinese medicine residues at 105 ℃ of 100-.
5. The improver for soil polluted by complex heavy metals according to claim 1, wherein: the calcium superphosphate powder is prepared by the following method: will P2O5The calcium superphosphate with the content of 14-20 percent is dried by airflow at the temperature of 100 ℃ and 250 ℃ until the water content is less than 2 percent, and is ground and sieved by a sieve with 200 meshes at 150 ℃.
6. The preparation method of the improver for compounding heavy metal contaminated soil according to claim 1, characterized by comprising the steps of: mixing the steel slag powder, the calcium phosphate powder and the phosphate-loaded charcoal according to the weight percentage, stirring for 0.5-1h by a dry method until the mixture is uniform, and then sieving by a sieve of 150 meshes and 200 meshes to obtain the modifying agent.
7. The use method of the improver for compounding heavy metal contaminated soil according to claim 1, wherein: and mixing and stirring the modifying agent and the heavy metal polluted soil, wherein the dosage of the modifying agent is 5-15% of the dry weight of the heavy metal polluted soil, and the water content of the heavy metal polluted soil is 16-30%.
8. The use method of the improver for soil polluted by complex heavy metals according to claim 7, wherein: the content of particles with the particle diameter of less than 0.075mm in the heavy metal polluted soil is 65-100%, wherein the content of heavy metal lead is more than 2000mg/kg, the content of heavy metal zinc is more than 2000mg/kg, the content of heavy metal copper is more than 2000mg/kg, and the content of heavy metal nickel is more than 2000 mg/kg.
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| CN110157447A (en) * | 2019-05-22 | 2019-08-23 | 辽宁工程技术大学 | A kind of dust storm soil conditioner and preparation method thereof and application method |
| CN110559998A (en) * | 2019-10-18 | 2019-12-13 | 清华大学 | Loaded biochar functional material for adsorbing heavy metal ions as well as preparation and application thereof |
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