CN113617822B - Heavy metal polluted foundation soil restoration and safe reuse method - Google Patents
Heavy metal polluted foundation soil restoration and safe reuse method Download PDFInfo
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- CN113617822B CN113617822B CN202110974391.7A CN202110974391A CN113617822B CN 113617822 B CN113617822 B CN 113617822B CN 202110974391 A CN202110974391 A CN 202110974391A CN 113617822 B CN113617822 B CN 113617822B
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- soil
- fine
- coarse
- heavy metal
- mixture
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- 239000002689 soil Substances 0.000 title claims abstract description 306
- 229910001385 heavy metal Inorganic materials 0.000 title claims abstract description 38
- 238000000034 method Methods 0.000 title claims abstract description 34
- 239000003381 stabilizer Substances 0.000 claims abstract description 74
- 238000011282 treatment Methods 0.000 claims abstract description 63
- 238000002156 mixing Methods 0.000 claims abstract description 50
- 239000003607 modifier Substances 0.000 claims abstract description 44
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 39
- 239000000203 mixture Substances 0.000 claims abstract description 36
- 238000012216 screening Methods 0.000 claims abstract description 32
- 238000004064 recycling Methods 0.000 claims abstract description 26
- 239000011449 brick Substances 0.000 claims abstract description 10
- 239000000945 filler Substances 0.000 claims abstract description 8
- 238000011221 initial treatment Methods 0.000 claims abstract description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 86
- 239000011651 chromium Substances 0.000 claims description 52
- NIFIFKQPDTWWGU-UHFFFAOYSA-N pyrite Chemical class [Fe+2].[S-][S-] NIFIFKQPDTWWGU-UHFFFAOYSA-N 0.000 claims description 51
- 229910052785 arsenic Inorganic materials 0.000 claims description 50
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 claims description 50
- 239000000463 material Substances 0.000 claims description 47
- 239000000843 powder Substances 0.000 claims description 40
- 239000002893 slag Substances 0.000 claims description 38
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 35
- 229910052804 chromium Inorganic materials 0.000 claims description 35
- 229910052742 iron Inorganic materials 0.000 claims description 31
- 238000005245 sintering Methods 0.000 claims description 27
- 229910052683 pyrite Inorganic materials 0.000 claims description 26
- 239000011028 pyrite Substances 0.000 claims description 26
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 claims description 19
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 claims description 19
- WZISDKTXHMETKG-UHFFFAOYSA-H dimagnesium;dipotassium;trisulfate Chemical compound [Mg+2].[Mg+2].[K+].[K+].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O WZISDKTXHMETKG-UHFFFAOYSA-H 0.000 claims description 18
- 238000004519 manufacturing process Methods 0.000 claims description 18
- 239000002699 waste material Substances 0.000 claims description 16
- 150000007524 organic acids Chemical class 0.000 claims description 15
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 14
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 13
- 239000002253 acid Substances 0.000 claims description 11
- 238000000227 grinding Methods 0.000 claims description 11
- -1 iron aluminate Chemical class 0.000 claims description 11
- 239000011148 porous material Substances 0.000 claims description 11
- 238000007873 sieving Methods 0.000 claims description 11
- QJZYHAIUNVAGQP-UHFFFAOYSA-N 3-nitrobicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid Chemical compound C1C2C=CC1C(C(=O)O)C2(C(O)=O)[N+]([O-])=O QJZYHAIUNVAGQP-UHFFFAOYSA-N 0.000 claims description 9
- 238000001035 drying Methods 0.000 claims description 9
- 239000004021 humic acid Substances 0.000 claims description 9
- 235000013379 molasses Nutrition 0.000 claims description 9
- 239000004568 cement Substances 0.000 claims description 8
- 229920000049 Carbon (fiber) Polymers 0.000 claims description 7
- 150000001413 amino acids Chemical class 0.000 claims description 7
- 239000004917 carbon fiber Substances 0.000 claims description 7
- 239000002002 slurry Substances 0.000 claims description 7
- 239000004408 titanium dioxide Substances 0.000 claims description 7
- 230000004913 activation Effects 0.000 claims description 6
- 239000003513 alkali Substances 0.000 claims description 6
- 239000004033 plastic Substances 0.000 claims description 6
- 229920003023 plastic Polymers 0.000 claims description 6
- 235000015165 citric acid Nutrition 0.000 claims description 5
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 5
- 235000002906 tartaric acid Nutrition 0.000 claims description 5
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 claims description 4
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 claims description 4
- 239000012530 fluid Substances 0.000 claims description 4
- 239000000395 magnesium oxide Substances 0.000 claims description 4
- KDYFGRWQOYBRFD-UHFFFAOYSA-N succinic acid Chemical compound OC(=O)CCC(O)=O KDYFGRWQOYBRFD-UHFFFAOYSA-N 0.000 claims description 4
- 239000011975 tartaric acid Substances 0.000 claims description 4
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 3
- BJEPYKJPYRNKOW-REOHCLBHSA-N (S)-malic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O BJEPYKJPYRNKOW-REOHCLBHSA-N 0.000 claims description 2
- BJEPYKJPYRNKOW-UHFFFAOYSA-N alpha-hydroxysuccinic acid Natural products OC(=O)C(O)CC(O)=O BJEPYKJPYRNKOW-UHFFFAOYSA-N 0.000 claims description 2
- YQRTZUSEPDULET-UHFFFAOYSA-K magnesium;potassium;phosphate Chemical compound [Mg+2].[K+].[O-]P([O-])([O-])=O YQRTZUSEPDULET-UHFFFAOYSA-K 0.000 claims description 2
- 235000011090 malic acid Nutrition 0.000 claims description 2
- 239000001630 malic acid Substances 0.000 claims description 2
- 238000003825 pressing Methods 0.000 claims description 2
- 239000001384 succinic acid Substances 0.000 claims description 2
- 235000011044 succinic acid Nutrition 0.000 claims description 2
- 238000011065 in-situ storage Methods 0.000 abstract description 3
- 238000012360 testing method Methods 0.000 description 98
- 230000000052 comparative effect Effects 0.000 description 55
- 238000002386 leaching Methods 0.000 description 35
- 238000005067 remediation Methods 0.000 description 24
- 238000012545 processing Methods 0.000 description 15
- 239000002245 particle Substances 0.000 description 13
- 230000008439 repair process Effects 0.000 description 12
- 238000002360 preparation method Methods 0.000 description 10
- 239000003795 chemical substances by application Substances 0.000 description 9
- 230000000694 effects Effects 0.000 description 9
- 239000003518 caustics Substances 0.000 description 8
- 239000010802 sludge Substances 0.000 description 8
- 230000001988 toxicity Effects 0.000 description 8
- 231100000419 toxicity Toxicity 0.000 description 8
- 239000000725 suspension Substances 0.000 description 7
- 239000007853 buffer solution Substances 0.000 description 6
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 6
- 239000000049 pigment Substances 0.000 description 6
- 238000006722 reduction reaction Methods 0.000 description 6
- 241000196324 Embryophyta Species 0.000 description 5
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 5
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 5
- 239000002734 clay mineral Substances 0.000 description 5
- 238000009713 electroplating Methods 0.000 description 5
- 239000010419 fine particle Substances 0.000 description 5
- 230000035784 germination Effects 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 229910017604 nitric acid Inorganic materials 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- 239000002910 solid waste Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 4
- 235000010469 Glycine max Nutrition 0.000 description 4
- 244000068988 Glycine max Species 0.000 description 4
- 239000011398 Portland cement Substances 0.000 description 4
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 235000011941 Tilia x europaea Nutrition 0.000 description 4
- 230000003139 buffering effect Effects 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000010276 construction Methods 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 4
- 230000003628 erosive effect Effects 0.000 description 4
- 239000004571 lime Substances 0.000 description 4
- 238000010998 test method Methods 0.000 description 4
- 230000003213 activating effect Effects 0.000 description 3
- 238000005056 compaction Methods 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 238000003795 desorption Methods 0.000 description 3
- 230000035558 fertility Effects 0.000 description 3
- 239000003337 fertilizer Substances 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 3
- 238000005070 sampling Methods 0.000 description 3
- 230000006641 stabilisation Effects 0.000 description 3
- 238000011105 stabilization Methods 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 239000002023 wood Substances 0.000 description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 239000007900 aqueous suspension Substances 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 239000013522 chelant Substances 0.000 description 2
- 238000003889 chemical engineering Methods 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000007812 deficiency Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 239000003344 environmental pollutant Substances 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000001095 inductively coupled plasma mass spectrometry Methods 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
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- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002086 nanomaterial Substances 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
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 230000007226 seed germination Effects 0.000 description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 238000004448 titration Methods 0.000 description 2
- 238000000954 titration curve Methods 0.000 description 2
- DJHGAFSJWGLOIV-UHFFFAOYSA-K Arsenate3- Chemical compound [O-][As]([O-])([O-])=O DJHGAFSJWGLOIV-UHFFFAOYSA-K 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- MBMLMWLHJBBADN-UHFFFAOYSA-N Ferrous sulfide Chemical compound [Fe]=S MBMLMWLHJBBADN-UHFFFAOYSA-N 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 description 1
- 229930006000 Sucrose Natural products 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- VETKVGYBAMGARK-UHFFFAOYSA-N arsanylidyneiron Chemical compound [As]#[Fe] VETKVGYBAMGARK-UHFFFAOYSA-N 0.000 description 1
- 229940000489 arsenate Drugs 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000004071 biological effect Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 150000001844 chromium Chemical class 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 238000010835 comparative analysis Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000004043 dyeing Methods 0.000 description 1
- 230000000674 effect on sodium Effects 0.000 description 1
- 231100000584 environmental toxicity Toxicity 0.000 description 1
- 238000011066 ex-situ storage Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000011790 ferrous sulphate Substances 0.000 description 1
- 235000003891 ferrous sulphate Nutrition 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000002779 inactivation Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 150000002500 ions Chemical group 0.000 description 1
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 1
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 1
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 1
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 1
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 1
- 239000010985 leather Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 230000008635 plant growth Effects 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001021 polysulfide Polymers 0.000 description 1
- 239000005077 polysulfide Substances 0.000 description 1
- 150000008117 polysulfides Polymers 0.000 description 1
- 238000004382 potting Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000012954 risk control Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- HRZFUMHJMZEROT-UHFFFAOYSA-L sodium disulfite Chemical compound [Na+].[Na+].[O-]S(=O)S([O-])(=O)=O HRZFUMHJMZEROT-UHFFFAOYSA-L 0.000 description 1
- 229940001584 sodium metabisulfite Drugs 0.000 description 1
- 235000010262 sodium metabisulphite Nutrition 0.000 description 1
- 229910052979 sodium sulfide Inorganic materials 0.000 description 1
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 1
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 1
- 235000019345 sodium thiosulphate Nutrition 0.000 description 1
- 238000003900 soil pollution Methods 0.000 description 1
- 238000009331 sowing Methods 0.000 description 1
- 238000002798 spectrophotometry method Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
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- 229960004793 sucrose Drugs 0.000 description 1
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- 239000004753 textile Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
-
- 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
- Y02W30/78—Recycling of wood or furniture waste
Landscapes
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Soil Sciences (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention discloses a method for repairing and safely recycling heavy metal polluted foundation soil, which comprises the steps of crushing and screening the heavy metal polluted foundation soil into coarse grain groups and fine grain groups, and adjusting the water content to obtain first-stage treated coarse grain soil and first-stage treated fine grain soil; uniformly mixing the first stabilizer with the primary-treatment coarse-grained soil to obtain secondary-treatment coarse-grained soil; uniformly mixing a second stabilizer with the primary-treatment fine soil to obtain secondary-treatment fine soil; uniformly mixing the first performance modifier with the secondary treatment coarse-grained soil, and safely recycling the mixture as the planting soil of the road green belt; the second performance modifier and the secondary treatment fine-grained soil are uniformly mixed and used as the road subgrade filler of the non-motor vehicle for safe reutilization, or the mixture is prepared into baking-free bricks and used as the flower bed enclosure wall in the greening area for safe reutilization. The method can fully realize the precise decrement restoration of the polluted foundation soil of the re-developed and utilized polluted land and the in-situ low-burden reuse of the restored soil.
Description
Technical Field
The invention relates to the field of environmental engineering, geotechnical engineering and traffic engineering, in particular to a method for repairing and safely recycling heavy metal polluted foundation soil.
Background
In the process of adjusting the industrial layout in China, a large amount of land vacated by the relocation of industrial enterprises in retirement effectively solves the problem of scarcity of land resources for urban development in China. However, a large amount of pollutants are accumulated in the removal and legacy site, and serious potential safety hazards are brought to land re-development and utilization. A large amount of arsenic-containing raw materials or waste materials are usually involved in the production processes of products such as glass, wood, leather, textiles, chemical engineering, ceramics, pigments, chemical fertilizers and the like, and a large amount of chromium-containing raw materials or waste materials are usually involved in the mining and smelting of chromium, the manufacturing of chromium salt, the surface treatment, the painting and dyeing industry, and the pollution of foundation soil of a production workshop is caused. Arsenic and chromium are highly toxic metals, which pose serious threats to the ecological environment and human health. Arsenic and chromium have high mobility in soil and are easily transmitted to the surrounding environment through groundwater. Therefore, there is a need to reduce the ecotoxicity of arsenic and chromium contaminated soils before they can be reused in contaminated sites or contaminated soils.
The ectopic stabilization treatment is widely adopted in the remediation of the arsenic and chromium polluted soil by virtue of the advantages of quick remediation time and convenient construction. However, ex-situ remediation and safe recycling of arsenic and chromium polluted foundation soil of the removed enterprises have the following defects: (1) the polluted foundation soil is usually directly excavated and restored after structures on the upper part of a plant area are dismantled, however, a large amount of construction waste, miscellaneous fill and polluted soil are mixed into a whole, so that the volume of restored soil is large, the particle size difference of the polluted soil is large, and the restoration cost is increased. (2) At present, the commonly used remediation agents for arsenic-polluted soil mainly comprise iron-based materials such as ferric sulfate, ferric chloride, polyferric sulfate and the like, and the remediation soil is low in strength, poor in long-term durability and limited in recycling mode. (3) The currently commonly used chromium-contaminated soil remediation agents mainly comprise iron-based and sulfur-based reducing agents such as nano zero-valent iron, ferrous sulfide, ferrous sulfate, sodium metabisulfite, sodium thiosulfate, sodium sulfide, calcium polysulfide and the like. However, the application of the nano material is limited due to the defects that the nano material is easy to agglomerate and deactivate, and hydrogen sulfide toxic gas is generated by sulfide. In addition, the structural damage, the reduction of biological activity and the deterioration of soil fertility of the restored soil limit the reuse of the restored soil as planting soil. (4) At present, the recycling mode of the restored soil is single, and the sustainability of safe recycling of the restored land mass is poor due to the fact that the requirements of site redevelopment on time base soil environment safety indexes, building engineering types and other differences cannot be combined.
Therefore, it is urgently needed to develop an innovative remediation and safe recycling method by combining the sustainable remediation and safe recycling requirements of arsenic-and chromium-polluted foundation soil in a demolition plant area, so as to fully realize accurate decrement remediation of the arsenic-polluted foundation soil in the polluted site and in-situ low-burden recycling of the remediation soil.
Disclosure of Invention
The invention aims to solve the technical problem of the prior art and provides a method for repairing and safely recycling heavy metal polluted foundation soil.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a method for restoring and safely recycling heavy metal polluted foundation soil comprises the following steps:
(1) crushing and screening the heavy metal polluted foundation soil into a coarse grain group and a fine grain group, adjusting the water content of the coarse grain group to 12-18% and the water content of the fine grain group to the optimal water content, and obtaining first-stage treatment coarse grain soil and first-stage treatment fine grain soil;
(2) uniformly mixing the first stabilizer and the first-stage treated coarse-grained soil, and standing for 7-14 days to obtain second-stage treated coarse-grained soil;
(3) uniformly mixing a second stabilizer with the primary-treatment fine soil, and standing for 7-14 days to obtain secondary-treatment fine soil;
(4) uniformly mixing the first performance modifier with the secondary treatment coarse-grained soil, and standing for 7-14 days to recycle the mixture as planting soil for a road green belt;
(5) the second performance modifier and the secondary treatment fine-grained soil are uniformly mixed and reused as the road subgrade filler of the non-motor vehicle, or the second performance modifier is prepared into baking-free bricks and reused as the flower bed enclosure safety in the greening area.
Wherein the heavy metal is arsenic or chromium.
Wherein the heavy metal contaminated land is a land vacated for industrial enterprises to move.
In the step (1), after the heavy metal polluted foundation soil is crushed, the foundation soil passes through a first sieve and a second sieve successively, the foundation soil which penetrates through the second sieve is a fine grain group, the foundation soil which penetrates through the first sieve but does not penetrate through the second sieve is a coarse grain group, and the foundation soil which does not penetrate through the first sieve needs to be crushed again; the diameter of a sieve pore of the first sieve is 9-15 cm; and the diameter of a sieve pore of the second sieve is 3-5 cm. In the prior art, some crushing equipment is provided with a screening part, the screening part of the crushing equipment is used as a first screen, the first screen is screened while crushing, and the second screen is screened after the first screen is screened.
The contaminated foundation soil is crushed and then screened into fine-grained soil and coarse-grained soil, because the content of clay minerals in the contaminated soil with different grain sizes is different, and the content of the clay minerals affects the chemical occurrence form of heavy metals, directly affects the leaching mechanism of the heavy metals and also determines the addition type and the addition amount of the repairing agent.
In the step (1), the optimal water content is obtained through a compaction test recommended in the soil test method standard (GB/T50123).
In the step (2), the step (3),
when the heavy metal is arsenic, the first stabilizer is a mixture of micron zero-valent iron powder, sodium persulfate and activated pyrite sintering slag, wherein the doping mass of the micron zero-valent iron powder, the sodium persulfate and the activated pyrite sintering slag is respectively 2% -7%, 4% -10% and 10% -40% of the dry weight of the first-stage treatment coarse-grained soil;
when the heavy metal is chromium, the first stabilizer is a mixture of sponge iron, pyrite powder and organic acid, wherein the doping mass of the sponge iron, the pyrite powder and the organic acid is respectively 10-20%, 10-30% and 5-15% of the dry weight of the first-stage treated coarse-grained soil; the organic acid is one or a mixture of more of tartaric acid, citric acid, succinic acid and malic acid; preferably a combination of tartaric and citric acids.
In the step (3), the step (c),
when the heavy metal is arsenic, the second stabilizer is a mixture of micron zero-valent iron powder, sodium persulfate, alkali slag and activated pyrite sintering slag, wherein the doping mass of the micron zero-valent iron powder, the sodium persulfate, the alkali slag and the activated pyrite sintering slag is respectively 2-7%, 4-10%, 10-40% and 10-30% of the dry weight of the first-stage treated fine-grained soil;
when the heavy metal is chromium, the second stabilizer is a mixture of micron zero-valent iron powder, amino acid chelated iron and alkali slag, and the doping mass of the micron zero-valent iron powder, the amino acid chelated iron and the alkali slag is 5% -10%, 5% -20% and 5% -10% of the dry weight of the first-stage treated fine soil respectively.
Preferably, the activated pyrite sinter slag is prepared by the following steps: (I) drying and grinding pyrite sintering slag, and sieving the pyrite sintering slag by using a 0.075mm sieve to obtain a first-stage activation material; (II) mixing the primary activating material with biochar, dissolving the mixture in waste acid produced by titanium dioxide, and completely reacting under the ultraviolet irradiation condition to obtain a secondary activating material; (III) drying, grinding and sieving the secondary activated material through a 0.075mm sieve. In the step (II), the waste acid from titanium dioxide production contains iron impurities, and the process can just utilize iron ions in the waste acid, so that waste is changed into valuable. In the step (II), the reaction is generally carried out for 0.5 to 1 hour under the ultraviolet irradiation condition until the pH value of the reaction system is unchanged, so that the reaction is complete.
The present invention treats coarse-grained soil and fine-grained soil with two stabilizers, respectively, because,
aiming at arsenic pollution:
the activated pyrite sinter in the first stabilizer has strong activation effect on sodium persulfate, and the generated SO 4- The free radicals can quickly oxidize trivalent arsenic in soil pore water into pentavalent arsenic, so that the ecological toxicity of the polluted soil is reduced (the higher the valence state of the arsenic, the lower the ecological toxicity); meanwhile, iron ions dissolved out from the activated pyrite sintering slag and arsenate (pentavalent) ions form insoluble precipitates. In addition, trivalent arsenic in coarse-grained soil tends to concentrate in the lump building waste, and the rate of migration from the matrix into the soil pores is slow. The zero-valent nano iron powder in the first stabilizer can maintain the continuous oxidation reaction, and the pseudo oxidation phenomenon of trivalent arsenic in coarse-grained soil is avoided.
The second stabilizer has a similar treatment mechanism to the first stabilizer on arsenic, but the fine-grained soil contains more clay minerals and the adsorption state of trivalent arsenic is higher. By adding the alkaline residue, the desorption of arsenic-containing anions on the surface of the clay mineral is promoted, and the generation amount of indissolvable iron-arsenic precipitates is increased.
Aiming at chromium pollution:
the surface activity of the pyrite powder in the first stabilizer is increased under the erosion action of the organic acid, the adsorption strength and the capacity of chromate on the surface of the pyrite powder in soil pore water can be remarkably increased, and hexavalent chromium is quickly reduced to trivalent chromium and adsorbed on the surface of pyrite (the lower the valence state of the chromium is, the lower the ecological toxicity is). In addition, hexavalent chromium in coarse-grained soil tends to concentrate in the bulk construction waste, which migrates from the matrix into the soil pores at a slower rate. The sponge iron in the first stabilizer can maintain the continuous operation of the reduction reaction, and the pseudo reduction phenomenon of hexavalent chromium in coarse-grained soil is avoided.
Secondly, the alkaline residue in the second stabilizer promotes the desorption of chromate ion on the surface of the clay mineral; meanwhile, the amino acid chelated iron can rapidly adsorb chromate ions in the pore water, so that the desorption reaction is promoted, and the concentration of the chromate ions in the pore water is maintained at a relatively stable level; the micro zero-valent iron powder stably and continuously reacts with chromate ions in pore water, and the surface inactivation of the micro iron powder caused by rapid concentration change is effectively avoided.
In the step (4), the step (C) is carried out,
when the heavy metal is arsenic, the first performance modifier is a mixture of potassium magnesium sulfate and molasses, wherein the mixing amount of the potassium magnesium sulfate and the molasses is 3% -8% and 5% -15% of the dry weight of the secondary treatment coarse-grained soil respectively;
when the heavy metal is chromium, the first performance modifier is a mixture of potassium magnesium sulfate and humic acid, and the mixing amount of the potassium magnesium sulfate and the humic acid is 3% -8% and 5% -15% of the dry weight of the secondary treatment coarse-grained soil respectively.
In the step (5), the first step is that,
when the heavy metal is arsenic, the second performance modifier is a low-alkalinity cementing material, wherein the doping amount of the low-alkalinity cementing material is 5-20% of the dry weight of the secondary treated fine-grained soil;
when the heavy metal is chromium, the second performance modifier is a mixture of a low-alkalinity cementing material and carbon fibers, wherein the mixing amount of the low-alkalinity cementing material and the carbon fibers is 20-50% and 5-10% of the dry weight of the secondary treatment fine soil respectively;
the low-alkaline cementing material is any one or a mixture of more of iron aluminate cement, magnesia activated and ground granulated blast furnace slag and magnesium potassium phosphate cement. The magnesium oxide activated, ground and granulated blast furnace slag is a mixture of magnesium oxide and ground and granulated blast furnace slag according to a mass ratio of (1: 9-1: 4).
Based on the difference of safe recycling ways of coarse-grained soil and fine-grained soil, the invention uses two performance modifiers.
The first performance modifier is used for improving the fertility, the permeability, the organic matter content (increasing the soil fertility) and the soil buffering capacity (increasing the durability of the remediation effect) of the remediation soil, so that the remediation soil is more suitable for plant growth.
The second performance modifier is used for improving the strength of the restoring soil, reducing the permeability and reducing the erosion effect of the atmospheric environment on the restoring soil, so that the restoring soil has better performance as roadbed filling and baking-free bricks.
In the step (5), when the material is reused as the non-motor vehicle road subgrade filler, the compaction degree is more than 92%, and the material is maintained for 7-14 days.
In the step (5), the method for preparing the baking-free brick comprises the following steps: (i) uniformly mixing the second performance modifier and the secondary treatment fine-grained soil, and then adding water, wherein the addition amount of the water accounts for 30-50% of the total mass of the second performance modifier and the secondary treatment fine-grained soil, so as to obtain flow plastic slurry; (ii) and (4) injecting the flowing plastic slurry into a baking-free brick pressing grinding tool for curing for 14-28 days, and then demolding.
Has the beneficial effects that: compared with the prior art, the invention has the following advantages:
(1) the invention divides the polluted foundation soil into a coarse grain group and a fine grain group through crushing and screening treatment. After screening, the chemical forms of arsenic or chromium in the two types of particle group polluted soil, the mineral compositions of the soil and the safe recycling mode are obviously different, and the possibility is provided for the precise design of the doping amount of the treating agent.
(2) The invention provides special repairing agents for the coarse grain group and the fine grain group respectively, realizes the accurate classified repair of the polluted foundation soil to a great extent, and obviously reduces the overall repair cost of the polluted foundation.
(3) The treatment capacity of the novel repairing material on arsenic or chromium polluted foundations is obviously higher than that of the traditional iron and sulfur-based materials, the durability is obviously improved, and the repairing efficiency is high.
(4) The invention combines the mode of redevelopment of the restoration site to carry out engineering improvement on the restored polluted foundation soil in a targeted way, so that the requirements of environmental safety and engineering safety for safe recycling are met.
(5) The maximum treatment concentration of the arsenic and chromium polluted soil in the invention is respectively 2800mg/kg and 1560mg/kg, which are respectively 20 times of the second type land control value in the soil environmental quality construction land soil pollution risk control value.
Detailed Description
The experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified.
The purity of the micron zero-valent iron powder in the following examples is 99.3%; sodium persulfate and potassium magnesium sulfate are analytically pure, pyrite sintering slag, molasses waste liquid and alkaline residue are sulfuric acid, cane sugar and sodium carbonate industrial byproducts respectively, and the storage time after leaving a factory is within 15 days; the waste acid from titanium dioxide production is waste from titanium dioxide production by sulfuric acid process, and the storage time after leaving factory is within 15 days.
The sponge iron in the following examples had a maximum particle size of 5mm and iron and carbon contents of 75% and 24%, respectively; grinding the pyrite powder through a 0.075mm sieve; the organic acid and the low-alkaline material have industrial grade purity; the content of the iron element in the micron zero-valent iron powder is 99.5 percent; potassium magnesium sulfate and humic acid are agricultural fertilizers; the caustic sludge is a sodium carbonate industrial byproduct, and the storage time after leaving the factory is within 15 days.
The sample preparation process described in the following examples was: the medicament with the set mixing amount is mixed and evenly mixed with the polluted foundation soil, and the mixture is filled into a polyethylene sealing bag.
The contents and the blending amounts in the following examples are mass contents unless otherwise specified.
The standard curing is carried out at 25 ℃ and 95% humidity in the following examples, and the curing time is 28 days without compacting the soil (i.e., in a dispersed state).
The toxicity leaching test in the following examples was carried out in accordance with the sulfuric acid nitric acid method (HJ/T299) which is a method of leaching toxicity from solid wastes. For ease of comparison, the arsenic leach concentrations of the examples and comparative examples were converted to arsenic repair rates (R) r ) The calculation method is R r The arsenic recovery concentration of the contaminated soil is multiplied by 100. The heavy metal concentration (total amount) test is carried out according to the determination of metal elements in solid waste by inductively coupled plasma mass spectrometry (HJ 766).
In the following examples, the test of toxicity leaching was carried out by referring to the sulfuric acid nitric acid method (HJ/T299) which is a method of leaching toxicity leaching of solid wastes. And (3) measuring the concentration of hexavalent chromium in the leaching solution by using a diphenylcarbonyldihydrazide spectrophotometric method. For convenience of comparison, the chromium leaching concentrations of examples and comparative examples were converted into chromium repair rates (R) r ) The calculation method is R r The yield of the soil is (polluted soil hexavalent chromium leaching concentration-restored soil hexavalent chromium leaching concentration)/polluted soil chromium restoration concentration multiplied by 100%. The chromium concentration (total) test was carried out with reference to "determination of metallic elements in solid waste inductively coupled plasma mass spectrometry" (HJ 766).
The germination rate test of the seeds adopts soybeans which are sensitive to the mobility of heavy metal pollutants in the soil, and the germination rate of the soybeans is used as an ecological index to carry out toxicity analysis on the soil. Firstly, naturally drying the plain soil and the restored soil which are maintained for 28 days. Taking 4kg of soil (plain soil or each repair soil) for potting (the diameter of an upper opening is 40cm, the diameter of a bottom is 30cm, the height is 20cm), and the ridging height is 18 cm; the soil in the pot is fully poured by 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, a spraying mode is regularly adopted to keep proper soil humidity, so that seeds germinate at indoor sunny places 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 soil acid buffer capacity Test was conducted according to the Test method recommended by STEGEMANN et al (STEGEMANN J A, COTE P L. investment of Test Methods for solid Waste materials) Evaluation,Appendix B:Test Methods for Solidified Waste Evaluation[R]Environmental Canada script Series, Document T5-15, Burlington, Ontario, Canada,1991: 49-52.). The test was carried out using a model ZDJ-4A automatic potentiometric titrator of the Remao brand. Weighing 20g of dry soil (screened by a 2mm sieve), adding 200mL of distilled water, and fully stirring by using a glass rod to prepare uniform suspension; then using a syringe equipped with a disposable needle filter to collect a proper amount of clear liquid of the soil-water suspension, quickly measuring the pH value of the clear liquid, determining the initial titration pH value according to the pH value, and finishing the setting of the working mode of the automatic titrator. And presetting the pH value of the target suspension to be an integral value smaller than the initial pH value of the suspension. ② transferring the soil-water suspension to an electrolytic cup. In order to ensure the solution in the electrolytic cup is uniform in the process of the test station, the electrolytic cup is placed on a magnetic stirrer. Starting the automatic titrator, and slowly dripping nitric acid solution into the soil liquid turbid liquid. When the pH value of the suspension reaches a target value, the automatic titrator records and displays the volume of the nitric acid solution in the test section, records the volume of the nitric acid solution and converts the volume into the nitric acid amount (cmol/kg) consumed by the soil sample of unit mass; and thirdly, drawing a titration curve and calculating an acid buffer coefficient. And (4) drawing a titration curve according to the consumption of nitric acid in titration of different pH values of the target suspension. On the basis of the formula (beta ═ dC) A dpH) the acid buffer coefficient of the soil sample was calculated. Wherein beta is the acid buffer coefficient (cmol. kg) of the soil sample -1 ·pH -1 )；dC A The increment of the acid consumption of the soil sample per unit mass (cmol/kg); dpH is the pH value increment of the suspension. The acid buffering capacity (. beta.) was determined for the suspension at pH 5 for comparative analysis.
The unconfined compressive strength test is carried out by using a YSH-2 strain control type unconfined compressive strength instrument with the axial strain rate of 1%/min by referring to road geotechnical test regulation (JTG E40-2007). And testing the unconfined compressive strength of the soil at the corresponding curing age.
A first part: arsenic-contaminated foundation soil remediation
The test is carried out on arsenic-polluted soil, and the test designs and test results of the corresponding examples and the comparative examples are as follows:
example 1
Selecting base soil of typical polluted ground such as wood, chemical engineering, pigment and fertilizer production workshops, and taking the soil to a depth of 20 cm. The contaminated soil was crushed to a size of 10cm (i.e., the crushing apparatus was equipped with a first sieve having a mesh diameter of 10cm, and the meanings shown in the following examples and comparative examples are the same). The contaminated foundation soil after crushing (i.e. without secondary screening, unscreened in the table) was tested directly for arsenic concentration and leaching concentration. The test results are shown in table 1.
Comparative example 1
The contaminated foundation soil after the crushing in example 1 was sieved to have a mesh opening size of 5 cm. The coarse soil (i.e., having a particle size of greater than 5cm) and the fine soil (i.e., having a particle size of less than 5cm) obtained by sieving were tested for arsenic concentration and leaching concentration, respectively. The test results are shown in table 1. "< 0.10" in the table means that it is below the detection limit.
TABLE 1 arsenic concentrations and leach concentrations in arsenic-contaminated coarse-grained soil and fine-grained soil before and after screening of foundation soil
As can be seen from Table 1, the arsenic concentrations in the coarse-grained soils and the fine-grained soils of the contaminated foundation soils of different production types are different from the leaching concentration. In addition, the comparison between the front and the back of the screening of the contaminated foundation soil in the wood production workshop shows that the arsenic leaching concentration of the soil before the screening is 53.19 mu g/L, exceeds the standard limit value of IV-type underground water and needs to be repaired; after screening treatment, the coarse particle group and the fine particle group are respectively 9.31 mu g/L and 60.24 mu g/L, wherein only the arsenic leaching concentration of the fine particle soil exceeds the standard limit value of IV-type underground water, namely only the fine particle soil needs to be repaired. It can therefore be estimated that the remediation volume of contaminated soil after screening is reduced to 75% of the remediation volume of the soil before screening.
Example 2
The test soil adopts pigment to produce industrial polluted foundation soil, and the concentration of arsenic in the soil is 1197 mg/kg. The polluted soil is crushed, the particle size of the crushed soil is 10cm, and the first stabilizer is selected as the repairing material. The mass ratio of the micron zero-valent iron powder, the sodium persulfate and the activated pyrite sintering slag in the first stabilizer is 3:5: 12. The doping amount of the repairing material ranges from 10% to 30% (accounting for the dry weight of the polluted soil), and the increment is 1%. And testing the arsenic leaching concentration under the conditions of different doping amounts of the repair material after sample preparation and maintenance are finished, and comparing the arsenic leaching concentration with a standard value of underground water IV. According to the sequence of the doping amount of the repairing materials from high to low, the arsenic leaching concentration of the repairing soil and a standard value of underground water IV are compared one by one, and the doping amount of the repairing agent corresponding to the first doping amount lower than the standard value is a critical doping amount. The test results are shown in table 2.
The activated pyrite sintering slag is prepared by the following steps: (I) drying and grinding pyrite sintering slag, and sieving the pyrite sintering slag by using a 0.075mm sieve to obtain a first-stage activation material; (II) mixing the primary activated material and biochar, dissolving the mixture in waste acid generated in titanium dioxide production, and completely reacting under the ultraviolet irradiation condition to obtain a secondary activated material; (III) drying, grinding and sieving the secondary activated material through a 0.075mm sieve.
Comparative example 2
The contaminated foundation soil of example 2 was subjected to the screening method of comparative example 1 (mesh opening size of 5cm) to obtain coarse fraction and fine fraction. The test sample preparation, test and critical doping amount judgment were the same as those of example 2. The only difference is that the test soil is a coarse grain group after screening of the pigment production industrial pollution foundation soil. The test results are shown in table 2.
Comparative example 3
The contaminated foundation soil of example 2 was sieved (5 cm mesh size) by the method of comparative example 1 to obtain coarse fraction and fine fraction. The test sample preparation, test and critical doping amount judgment were the same as those in example 2. The only difference is that the test soil is a fine particle group after screening of the pigment production industrial pollution foundation soil. The test results are shown in table 2.
As can be seen from Table 2, the critical doping amounts of the contaminated foundation soil before screening were respectively 26%. The critical mixing amounts of the coarse soil and the fine soil of the polluted foundation soil after screening are respectively 27% and 16%. The results show that if the polluted foundation soil is screened and then subjected to stabilization treatment, the repair materials can be saved by 9 percent.
TABLE 2 Critical doping amounts of remediation agents for pre-screening contaminated soils and post-screening arsenic-contaminated coarse and fine fractions
Example 3
The sample preparation steps are as follows:
(1) the contaminated foundation soil for the test was obtained from the same pigment manufacturing plant as in example 2, except that the arsenic concentration in the contaminated foundation soil was 2800 mg/kg. The contaminated soil was crushed to a particle size of 10cm, and coarse-grained soil and fine-grained soil were obtained by the screening method of comparative example 1 (mesh opening size of 5cm), respectively. The arsenic concentration in the coarse soil and the fine soil is 1132mg/kg and 3715mg/kg respectively, and the arsenic leaching concentration is 123.11 mug/L and 177.53 mug/L respectively. Then, the water content of the coarse-grained soil and the water content of the fine-grained soil are respectively adjusted to obtain first-stage treated coarse-grained soil and first-stage treated fine-grained soil, wherein the water content of the coarse-grained soil is 16.0%, and the water content of the fine-grained soil is 18.5% (optimal water content).
(2) And uniformly mixing the first stabilizer and the first-stage treated coarse-grained soil, and standing for 14 days to obtain second-stage treated coarse-grained soil. Wherein the mixing amount of the micron zero-valent iron powder, the sodium persulfate and the activated pyrite sintering slag in the first stabilizer is respectively 4%, 7% and 25% of the dry weight of the first-stage treated fine-grained soil.
(3) And uniformly mixing the second stabilizer with the primary-treated fine soil, and standing for 14 days to obtain secondary-treated fine soil. Wherein, the micron zero-valent iron powder, the sodium persulfate, the caustic sludge and the activated pyrite sintering slag in the second stabilizer are respectively 5%, 7%, 25% and 20% of the dry weight of the first-stage treated fine-grained soil.
(4) And uniformly mixing the first performance modifier with the secondary-treatment coarse-grained soil, standing for 14 days, recycling the mixture as planting soil of a road green belt, and sampling to test arsenic leaching concentration, seed germination rate and acid buffer test. Wherein, the mass of the magnesium potassium sulfate and the mass of the molasses in the first performance modifier are respectively 6 percent and 10 percent of the dry weight of the secondary treatment coarse-grained soil. The test results are shown in table 3.
(5) The second performance modifier and the second-stage treated fine soil are uniformly mixed and are reused as the road bed filler of the non-motor vehicle. In order to simulate the recycling environment of the roadbed filler, the treated fine-grained soil is subjected to static pressure sample preparation, the compaction degree of the soil is 93%, and the arsenic leaching concentration and the unconfined compressive strength are tested by sampling after 14 days of maintenance. Wherein the second performance modifier is iron aluminate cement, and the mixing amount of the iron aluminate cement is 30% of the dry weight of the secondary treated fine-grained soil. The test results are shown in table 4.
In the steps (2) and (3), the activated pyrite sintering slag is prepared by the following steps: (I) drying and grinding pyrite sintering slag, and sieving the pyrite sintering slag by a 0.075mm sieve to obtain a first-stage activation material; (II) mixing the primary activated material and biochar, dissolving the mixture into waste acid generated in titanium dioxide production, and completely reacting after ultraviolet irradiation for 0.5-1 hour to obtain a secondary activated material; (III) drying, grinding and sieving the secondary activated material through a 0.075mm sieve.
Comparative example 4
The first stabilizer contained no micron zero valent iron powder and the other treatment was the same as in example 3. The test results are shown in table 3.
Comparative example 5
The first stabilizer contained no sodium persulfate, and the other treatments were the same as in example 3. The test results are shown in table 3.
Comparative example 6
The first stabilizer contained no activated pyrite clinker, and the other treatment was the same as in example 3. The test results are shown in table 3.
Comparative example 7
The first stabilizer contained only micron zero valent iron powder and the other treatment was the same as in example 3. The test results are shown in table 3.
Comparative example 8
The first stabilizer contained only sodium persulfate, and the other treatment was the same as in example 3. The test results are shown in table 3.
Comparative example 9
The first stabilizer contained only activated pyrite sinter, and the other treatment was the same as in example 3. The test results are shown in table 3.
Comparative example 10
The activated pyrite sinter contained in the first stabilizer is not activated, i.e., the pyrite sinter is only dried, ground and sieved through a 0.075mm sieve. Other processing was the same as in example 3. The test results are shown in table 3.
Comparative example 11
The first performance modifier only contains molasses, and the mixing amount is 10%. The other processing was the same as in example 3. The test results are shown in table 3.
Comparative example 12
The first performance modifier only contains magnesium potassium sulfate, and the mixing amount is 6%. Other processing was the same as in example 3. The test results are shown in table 3.
Comparative example 13
The second stabilizer contained no micron zero valent iron powder and the other treatment was the same as in example 3. The test results are shown in table 4.
Comparative example 14
The second stabilizer contained no sodium persulfate, and the other treatment was the same as in example 3. The test results are shown in table 4.
Comparative example 15
The second stabilizer contained no caustic sludge, and the other treatment was the same as in example 3. The test results are shown in table 4.
Comparative example 16
The second stabilizer contained no activated pyrite sinter and the other treatment was the same as in example 3. The test results are shown in table 4.
Comparative example 17
The second stabilizer contained only micron zero valent iron powder and the other treatment was the same as in example 3. The test results are shown in table 4.
Comparative example 18
The second stabilizer contained only sodium persulfate, and the other treatments were the same as in example 3. The test results are shown in table 4.
Comparative example 19
The second stabilizer contained only caustic sludge, and the other treatment was the same as in example 3. The test results are shown in table 4.
Comparative example 20
The second stabilizer contained only activated pyrite sinter, and the other treatment was the same as in example 3. The test results are shown in table 4.
Comparative example 21
The activated pyrite sinter contained in the second stabilizer is not activated, i.e., the pyrite sinter is only dried, ground and sieved through a 0.075mm sieve. Other processing was the same as in example 3. The test results are shown in table 4.
Comparative example 22
The second performance modifier is ordinary Portland cement with the mixing amount of 30 percent. The other processing was the same as in example 3. The test results are shown in table 4.
Comparative example 23
The second performance modifier only contains lime, and the mixing amount is 30%. The other processing was the same as in example 3. The test results are shown in table 4.
TABLE 3 test results of treating arsenic contaminated coarse-grained soil
TABLE 4 test results for treating arsenic contaminated fine soil
As can be seen from table 3, the (1) missing of any component in the mixture of the micron zero-valent iron powder, the sodium persulfate and the activated pyrite sintering slag as the first stabilizer causes the significant reduction of the remediation effect of the first stabilizer on the arsenic-contaminated soil. (2) The activation treatment of the pyrite sintering slag can obviously improve the effect of the first stabilizer on the arsenic-polluted soil remediation. (3) Compared with the independent use of potassium magnesium sulfate and molasses, the potassium magnesium sulfate and molasses in the first performance modifier are used in a matching manner, so that the germination and acid buffering capacity of seeds can be improved, and the plant tolerance and the external erosion resistance of the repair soil can be obviously improved.
As can be seen from table 4, the (1) deficiency of any component in the mixture of the micron zero-valent iron powder, the sodium persulfate, the caustic sludge and the activated pyrite sintering slag as the second stabilizer can cause the significant reduction of the remediation effect of the second stabilizer on the arsenic-contaminated soil. (2) The activating treatment of the pyrite sintering slag can obviously improve the repairing effect of the second stabilizer on the arsenic-polluted soil. (3) Compared with the common Portland cement and lime, the use of the low-alkalinity cementing material in the second performance improver can improve the strength of the restored soil and simultaneously maintain the arsenic leaching concentration at a lower level.
A second part: chromium contaminated foundation soil remediation
The test is carried out on the chromium (Cr) polluted foundation soil, and the test designs and test results of the corresponding examples and the comparative examples are as follows:
example 4
Selecting typical polluted foundation soil of electroplating, paint and dye production workshops and the like, wherein the soil taking depth is 20 cm. The polluted soil is crushed, and the particle size of the crushed soil is 10 cm. The contaminated foundation soil after crushing (i.e. without secondary screening, unscreened in the table) was tested directly for Cr concentration and Cr (iv) leaching concentration. The test results are shown in table 5.
Comparative example 24
The contaminated foundation soil after crushing in example 4 was sieved to have a mesh opening size of 5 cm. The coarse soil (i.e., having a particle size of greater than 5cm) and the fine soil (i.e., having a particle size of less than 5cm) obtained by sieving were tested for Cr concentration and Cr (IV) leaching concentration, respectively. The test results are shown in table 1.
TABLE 5 Cr (IV) concentration and leaching concentration in coarse-grained soil and fine-grained soil polluted by chromium before and after screening of foundation soil
As can be seen from Table 5, the concentrations of heavy metals in the coarse-grained soil and the fine-grained soil of the contaminated foundation soil of different production types were different from the leaching concentration. In addition, the comparison between the polluted foundation soil of the electroplating production workshop and the polluted foundation soil before and after screening shows that the leaching concentration of Cr (IV) in the soil before screening is 0.17mg/L, exceeds the IV-type underground water standard limit value and needs to be repaired; after screening treatment, the leaching concentrations of Cr (IV) in the coarse grain group and the fine grain group are respectively 0.08mg/L and 0.23mg/L, wherein only the leaching concentration of Cr (IV) in the fine grain soil exceeds the IV type underground water standard limit value and needs to be repaired. Therefore, it can be estimated that the remediation of contaminated soil after screening is reduced to 80% of that of unscreened soil.
Example 5
The test soil is the polluted foundation soil removed and left by the electroplating industry, and the Cr concentration in the soil is 1501 mg/kg. The polluted soil is crushed, the particle size of the crushed soil is 10cm, and the first stabilizer is selected as the repairing material. The mass ratio of the sponge iron, the pyrite powder and the organic acid in the first stabilizer is 2:3:1, wherein the organic acid is a mixture of tartaric acid and citric acid in the mass ratio of 1: 1. The mixing amount of the first stabilizer is 10-30% (accounting for the dry weight of the polluted soil), and the increment is 1%. And testing the leaching concentration of Cr (IV) under the conditions of different doping amounts of the repair material after sample preparation and maintenance are finished, and comparing the leaching concentration with a standard value of underground water IV. According to the sequence of the doping amount of the repairing materials from high to low, the leaching concentration of Cr (IV) of the repairing soil and a standard value of the IV of underground water are compared one by one, and the doping amount of the repairing agent corresponding to the first lower than the standard value is a critical doping amount. The test results are shown in table 6.
Comparative example 25
The contaminated foundation soil of example 5 was subjected to the screening method of comparative example 24 (mesh opening size of 5cm) to obtain coarse fraction and fine fraction. The test sample preparation, test and critical doping amount judgment were the same as those in example 5. The only difference is that the test soil is a coarse grain group after screening the electroplating industry polluted foundation soil. The test results are shown in table 6.
Comparative example 26
The contaminated foundation soil of example 5 was sieved (5 cm mesh opening) by the method of comparative example 24 to obtain coarse fraction and fine fraction. The test sample preparation, test and critical doping amount judgment were the same as those of example 5. The only difference is that the test soil is a fine particle group screened from the electroplating industry polluted foundation soil. The test results are shown in table 6.
As can be seen from Table 6, the critical doping amounts of the contaminated soils before screening were 11% respectively. The critical doping amount of the coarse soil and the fine soil of the polluted residue soil after screening is 6 percent and 21 percent respectively. The results show that if the polluted residue soil is screened and then subjected to stabilization treatment, the repair material can be saved by 5%.
TABLE 6 Critical dosing rates of remediation Agents for Pre-screened contaminated soil and post-screened chromium contaminated coarse and fine fractions
Example 6
The sample preparation steps are as follows:
(1) the contaminated foundation soil for the test was taken from the same plating plant as in example 5, except that the Cr concentration in the contaminated foundation soil was 1560 mg/kg. The contaminated soil was crushed to a particle size of 10cm, and coarse-grained soil and fine-grained soil were obtained by sieving with the method of comparative example 24 (mesh aperture of 5 cm). The Cr concentration in the coarse soil and the fine soil is 455mg/kg and 1921mg/kg respectively, and the Cr (IV) leaching concentration is 0.13mg/L and 0.19mg/L respectively. Then, the water content of the coarse-grained soil and the water content of the fine-grained soil are respectively adjusted to obtain first-stage treated coarse-grained soil and first-stage treated fine-grained soil, wherein the water content of the coarse-grained soil is 15.2%, and the water content of the fine-grained soil is 17.5% (optimal water content).
(2) And uniformly mixing the first stabilizer and the first-stage treated coarse-grained soil, and standing for 14 days to obtain second-stage treated coarse-grained soil. Wherein the mixing amount of the sponge iron, the pyrite powder and the organic acid in the first stabilizer is respectively 15%, 20% and 10% of the dry weight of the first-stage treated fine-grained soil, and the organic acid is a mixture of tartaric acid and citric acid in a mass ratio of 1: 1.
(3) And (3) uniformly mixing the second stabilizer with the primary-treated fine soil, and standing for 14 days to obtain secondary-treated fine soil. Wherein, the micron zero-valent iron powder, the amino acid chelated iron and the caustic sludge in the second stabilizer are respectively 7%, 15% and 7% of the dry weight of the first-grade treated fine soil.
(4) And (3) uniformly mixing the first performance improver and the secondary-treatment coarse soil, standing for 14 days, recycling the mixture as planting soil of a road green belt, and sampling to test Cr (IV) leaching concentration, seed germination rate and acid buffer test. Wherein, the mass of the magnesium potassium sulfate and the humic acid in the first performance modifier is respectively 5 percent and 10 percent of the dry weight of the secondary treatment coarse-grained soil. The test results are shown in table 7.
(5) The second performance modifier and the second-stage treatment fine soil are uniformly mixed, and the baking-free brick is prepared and used for the flower bed enclosing wall in the greening area for safe reuse. A forming process for simulating a baking-free brick by preparing a cylindrical sample in a laboratory comprises the following steps: (i) uniformly mixing the second performance modifier with the second-stage treatment fine-grained soil, and adding water, wherein the addition amount of the water accounts for 38% of the total mass of the second performance modifier and the second-stage treatment fine-grained soil, so as to obtain fluid plastic slurry; (ii) and injecting the fluid plastic slurry into the PVC sleeve, and slightly vibrating to discharge bubbles in the slurry. The diameter and height of the PVC sleeve are 5cm and 10cm, respectively. And (5) after curing for 21 days, demolding. The mixing amount of the ferro-aluminate cement and the carbon fiber in the second performance improver is respectively 30 percent and 6 percent of the dry weight of the secondary treatment fine grain soil. The test results are shown in table 8.
Comparative example 27
The first stabilizer contained no sponge iron, and the other treatments were the same as in example 6. The test results are shown in table 7.
Comparative example 28
The first stabilizer contained no pyrite powder and the other treatments were the same as in example 6. The test results are shown in table 7.
Comparative example 29
The first stabilizer contained no organic acid, and the other treatment was the same as in example 6. The test results are shown in table 7.
Comparative example 30
The first stabilizer only contains sponge iron, and the mixing amount is 15%. The other processing was the same as in example 6. The test results are shown in table 7.
Comparative example 31
The first stabilizer only contains pyrite powder, and the mixing amount is 20%. The other processing was the same as in example 6. The test results are shown in table 7.
Comparative example 32
The first stabilizer only contains organic acid, and the mixing amount is 20%. The other processing was the same as in example 6. The test results are shown in table 7.
Comparative example 33
The first performance modifier only contains humic acid, and the mixing amount is 10%. Other processing was the same as in example 6. The test results are shown in table 7.
Comparative example 34
The first performance modifier only contains magnesium potassium sulfate, and the mixing amount is 5%. The other processing was the same as in example 6. The test results are shown in table 7.
Comparative example 35
The second stabilizer contained no micron zero valent iron powder and the other treatment was the same as in example 6. The test results are shown in table 8.
Comparative example 36
The second stabilizer contained no iron amino acid chelate, and the other treatment was the same as in example 6. The test results are shown in table 8.
Comparative example 37
The second stabilizer contained no caustic sludge, and the other treatment was the same as in example 6. The test results are shown in table 8.
Comparative example 38
The second stabilizer contained only micron zero valent iron powder and the other treatment was the same as example 6. The test results are shown in table 8.
Comparative example 39
The second stabilizer contained only the iron amino acid chelate, and the other treatment was the same as in example 6. The test results are shown in table 8.
Comparative example 40
The second stabilizer contained only caustic sludge, and the other treatment was the same as in example 6. The test results are shown in table 8.
Comparative example 41
The second performance modifier only contains the ferro-aluminate cement, and the mixing amount is 30 percent. The other processing was the same as in example 6. The test results are shown in table 8.
Comparative example 42
The second performance modifier only contains carbon fiber, and the mixing amount is 6%. The other processing was the same as in example 6. The test results are shown in table 8.
Comparative example 43
The second performance modifier is ordinary Portland cement with the mixing amount of 36 percent. Other processing was the same as in example 6. The test results are shown in table 8.
Comparative example 44
The second performance modifier only contains lime, and the mixing amount is 36%. The other processing was the same as in example 6. The test results are shown in table 8.
TABLE 7 test results for treating chromium contaminated coarse grained soil
TABLE 8 test results for treating chromium contaminated fine grained soil
As shown in Table 7, the loss of any one of the components of the sponge iron, the pyrite powder and the organic acid contained in the first stabilizer can cause the first stabilizer to remarkably reduce the repairing effect of the Cr-polluted soil. (2) Compared with the single use of the magnesium potassium sulfate and the humic acid, the magnesium potassium sulfate and the humic acid in the first performance modifier are used in a matching way, so that the germination and acid buffering capacity of seeds can be improved, and the plant tolerance and the external erosion resistance of the repair soil can be obviously improved.
As can be seen from table 8, the (1) deficiency of any one of the micrometer zero-valent iron powder, the amino acid chelated iron and the alkaline residue contained in the second stabilizer can cause a significant reduction in the effect of the second stabilizer on the remediation of the Cr-contaminated soil. (2) Compared with ordinary portland cement and lime, the combined use of the low-alkalinity cementing material and the carbon fiber in the second performance modifier can improve the strength of the repair soil and simultaneously maintain the leaching concentration of Cr (IV) at a lower level.
In summary, the method for repairing and safely recycling the arsenic or chromium polluted foundation soil disclosed by the invention divides the residual chromium polluted foundation soil after the decommissioned enterprise into coarse-grained soil and fine-grained soil according to the particle size, and then adds the stabilizer and the performance modifier to treat the coarse-grained soil and the fine-grained soil respectively to be used as road subgrade filler of the non-motor vehicles or flower bed planting soil in the greening area and flower bed enclosing walls in the greening area for safe recycling. The repairing and safe recycling method can fully realize the accurate decrement repairing of the polluted foundation soil of the re-developed and utilized polluted land and the in-situ low-burden recycling of the repaired soil.
The invention provides a method for repairing and safely recycling heavy metal polluted foundation soil, and a plurality of methods and ways for specifically realizing the technical scheme are provided, and the method is only a preferred embodiment of the invention. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be construed as the protection scope of the present invention. All the components not specified in the present embodiment can be realized by the prior art.
Claims (4)
1. A method for restoring and safely recycling heavy metal polluted foundation soil is characterized by comprising the following steps:
(1) crushing and screening heavy metal polluted foundation soil into a coarse grain group and a fine grain group, adjusting the water content of the coarse grain group to 12% -18% and the water content of the fine grain group to the optimal water content, and obtaining first-stage treated coarse grain soil and first-stage treated fine grain soil;
(2) uniformly mixing the first stabilizer and the first-stage treated coarse-grained soil, and standing for 7-14 days to obtain second-stage treated coarse-grained soil;
(3) uniformly mixing a second stabilizer with the primary-treatment fine soil, and standing for 7-14 days to obtain secondary-treatment fine soil;
(4) uniformly mixing the first performance modifier with the secondary treatment coarse-grained soil, and standing for 7-14 days to safely recycle the mixture as planting soil of a road green belt;
(5) uniformly mixing the second performance modifier with the secondary treatment fine-grained soil, and recycling the mixture as a non-motor road subgrade filler, or preparing baking-free bricks for safe recycling of the flower bed enclosure in the greening area;
the heavy metal is arsenic or chromium;
in the step (1), after the heavy metal polluted foundation soil is crushed, the foundation soil passes through a first sieve and a second sieve successively, the foundation soil which penetrates through the second sieve is a fine grain group, the foundation soil which penetrates through the first sieve but does not penetrate through the second sieve is a coarse grain group, and the foundation soil which does not penetrate through the first sieve needs to be crushed again; the diameter of a sieve pore of the first sieve is 9-15 cm; the diameter of a sieve pore of the second sieve is 3-5 cm;
in the step (2), the step (3),
when the heavy metal is arsenic, the first stabilizer is a mixture of micron zero-valent iron powder, sodium persulfate and activated pyrite sintering slag, wherein the doping mass of the micron zero-valent iron powder, the sodium persulfate and the activated pyrite sintering slag is respectively 2-7%, 4-10% and 10-40% of the dry weight of the first-grade treated coarse-grained soil;
when the heavy metal is chromium, the first stabilizer is a mixture of sponge iron, pyrite powder and an organic acid, wherein the doping mass of the sponge iron, the pyrite powder and the organic acid is respectively 10-20%, 10-30% and 5-15% of the dry weight of the first-stage treated coarse-grained soil; the organic acid is one or a mixture of more of tartaric acid, citric acid, succinic acid and malic acid;
in the step (3), the step (c),
when the heavy metal is arsenic, the second stabilizer is a mixture of micron zero-valent iron powder, sodium persulfate, alkali slag and activated pyrite sintering slag, wherein the doping mass of the micron zero-valent iron powder, the sodium persulfate, the alkali slag and the activated pyrite sintering slag is respectively 2-7%, 4-10%, 10-40% and 10-30% of the dry weight of the first-grade treated fine soil;
when the heavy metal is chromium, the second stabilizer is a mixture of micron zero-valent iron powder, amino acid chelated iron and alkaline residue, and the doping mass of the micron zero-valent iron powder, the amino acid chelated iron and the alkaline residue is 5-10%, 5-20% and 5-10% of the dry weight of the first-stage treated fine soil respectively;
in the step (4), the step (C) is carried out,
when the heavy metal is arsenic, the first performance modifier is a mixture of potassium magnesium sulfate and molasses, wherein the mixing amount of the potassium magnesium sulfate and the molasses is 3% -8% and 5% -15% of the dry weight of the secondary treated coarse-grained soil respectively;
when the heavy metal is chromium, the first performance modifier is a mixture of potassium magnesium sulfate and humic acid, and the mixing amount of the potassium magnesium sulfate and the humic acid is 3% -8% and 5% -15% of the dry weight of the secondary-treatment coarse-grained soil respectively;
in the step (5), the step (c),
when the heavy metal is arsenic, the second performance modifier is a low-alkalinity cementing material, wherein the doping amount of the low-alkalinity cementing material is 5-20% of the dry weight of the secondary treated fine-grained soil;
when the heavy metal is chromium, the second performance modifier is a mixture of a low-alkalinity cementing material and carbon fibers, wherein the mixing amount of the low-alkalinity cementing material and the carbon fibers is 20-50% and 5-10% of the dry weight of the secondary treated fine soil respectively;
the low-alkalinity cementing material is any one or a mixture of more of iron aluminate cement, magnesium oxide activated and ground granulated blast furnace slag and magnesium potassium phosphate cement.
2. The method of claim 1, wherein the heavy metal contaminated land is land vacated for industrial enterprise relocation.
3. The method according to claim 1, characterized in that the activated pyrite sinter is prepared by: (I) drying and grinding pyrite sintering slag, and sieving the pyrite sintering slag by using a 0.075mm sieve to obtain a first-stage activation material; (II) mixing the primary activated material and biochar, dissolving the mixture in waste acid from titanium dioxide production, and completely reacting under the ultraviolet irradiation condition to obtain a secondary activated material; (III) drying, grinding and sieving the secondary activated material through a 0.075mm sieve.
4. The method according to claim 1, wherein, in step (5),
when the material is reused as a non-motor vehicle road subgrade filler, the compactness is more than 92%, and the material is maintained for 7-14 days;
the method for preparing the baking-free brick comprises the following steps: (i) uniformly mixing the second performance modifier and the secondary treatment fine-grained soil, and then adding water, wherein the addition amount of the water accounts for 30-50% of the total mass of the second performance modifier and the secondary treatment fine-grained soil, so as to obtain fluid plastic slurry; (ii) and (4) injecting the fluid plastic slurry into a baking-free brick pressing grinding tool, curing for 14-28 days, and demolding.
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