CN112718837A - Leaching system and process for mercury-polluted soil - Google Patents
Leaching system and process for mercury-polluted soil Download PDFInfo
- Publication number
- CN112718837A CN112718837A CN202011307657.4A CN202011307657A CN112718837A CN 112718837 A CN112718837 A CN 112718837A CN 202011307657 A CN202011307657 A CN 202011307657A CN 112718837 A CN112718837 A CN 112718837A
- Authority
- CN
- China
- Prior art keywords
- leaching
- tank
- soil
- heat conduction
- heating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000002386 leaching Methods 0.000 title claims abstract description 90
- 239000002689 soil Substances 0.000 title claims abstract description 76
- 238000000034 method Methods 0.000 title claims abstract description 26
- 238000010438 heat treatment Methods 0.000 claims abstract description 49
- 238000003756 stirring Methods 0.000 claims abstract description 48
- 230000008719 thickening Effects 0.000 claims abstract description 42
- 230000003647 oxidation Effects 0.000 claims abstract description 38
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 38
- 229910052753 mercury Inorganic materials 0.000 claims abstract description 29
- 238000004062 sedimentation Methods 0.000 claims abstract description 29
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 claims abstract description 28
- 230000001112 coagulating effect Effects 0.000 claims abstract description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 22
- 238000012216 screening Methods 0.000 claims abstract description 19
- 239000007788 liquid Substances 0.000 claims abstract description 13
- 238000004064 recycling Methods 0.000 claims abstract description 4
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 24
- 239000007800 oxidant agent Substances 0.000 claims description 17
- 230000001590 oxidative effect Effects 0.000 claims description 14
- 238000006243 chemical reaction Methods 0.000 claims description 12
- 239000002002 slurry Substances 0.000 claims description 12
- 239000000126 substance Substances 0.000 claims description 12
- 239000006228 supernatant Substances 0.000 claims description 11
- XUJNEKJLAYXESH-UHFFFAOYSA-N cysteine Natural products SCC(N)C(O)=O XUJNEKJLAYXESH-UHFFFAOYSA-N 0.000 claims description 10
- 235000018417 cysteine Nutrition 0.000 claims description 10
- 239000002245 particle Substances 0.000 claims description 10
- 239000003795 chemical substances by application Substances 0.000 claims description 7
- 239000002244 precipitate Substances 0.000 claims description 6
- 238000003825 pressing Methods 0.000 claims description 6
- 238000000926 separation method Methods 0.000 claims description 6
- 238000005406 washing Methods 0.000 claims description 6
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 5
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 5
- 235000011152 sodium sulphate Nutrition 0.000 claims description 5
- 230000014759 maintenance of location Effects 0.000 claims description 4
- 239000000706 filtrate Substances 0.000 claims description 3
- 239000002920 hazardous waste Substances 0.000 claims description 3
- 238000012423 maintenance Methods 0.000 claims description 3
- 238000005067 remediation Methods 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- 238000013019 agitation Methods 0.000 claims 2
- 238000005345 coagulation Methods 0.000 claims 2
- 230000015271 coagulation Effects 0.000 claims 2
- NZIAJMSMIOISDK-UHFFFAOYSA-L disodium 2-hydroxypropane-1,2,3-tricarboxylic acid sulfate Chemical group [Na+].[Na+].[O-]S([O-])(=O)=O.OC(=O)CC(O)(CC(O)=O)C(O)=O NZIAJMSMIOISDK-UHFFFAOYSA-L 0.000 claims 1
- 229910001385 heavy metal Inorganic materials 0.000 abstract description 14
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 239000010865 sewage Substances 0.000 abstract description 2
- 239000003814 drug Substances 0.000 description 7
- 238000002474 experimental method Methods 0.000 description 4
- 238000007711 solidification Methods 0.000 description 4
- 230000008023 solidification Effects 0.000 description 4
- 230000006641 stabilisation Effects 0.000 description 4
- 238000011105 stabilization Methods 0.000 description 4
- 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 description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- NLKNQRATVPKPDG-UHFFFAOYSA-M potassium iodide Chemical compound [K+].[I-] NLKNQRATVPKPDG-UHFFFAOYSA-M 0.000 description 3
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 description 3
- 229910052785 arsenic Inorganic materials 0.000 description 2
- 238000003795 desorption Methods 0.000 description 2
- 239000003480 eluent Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910052745 lead Inorganic materials 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000003900 soil pollution Methods 0.000 description 2
- 238000005527 soil sampling Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- ZGTMUACCHSMWAC-UHFFFAOYSA-L EDTA disodium salt (anhydrous) Chemical compound [Na+].[Na+].OC(=O)CN(CC([O-])=O)CCN(CC(O)=O)CC([O-])=O ZGTMUACCHSMWAC-UHFFFAOYSA-L 0.000 description 1
- 241000282414 Homo sapiens Species 0.000 description 1
- XUJNEKJLAYXESH-REOHCLBHSA-N L-Cysteine Chemical compound SC[C@H](N)C(O)=O XUJNEKJLAYXESH-REOHCLBHSA-N 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 150000002730 mercury Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 238000012954 risk control Methods 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
- 239000002904 solvent Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Images
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
- B09C1/02—Extraction using liquids, e.g. washing, leaching, flotation
-
- 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
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Soil Sciences (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention relates to a leaching system and a leaching process for mercury-polluted soil, which comprises a heating oxidation tank, a mechanical screening device, a leaching stirring tank, a primary thickening tank, a clear water leaching stirring tank, a secondary thickening tank and a plate-and-frame filter press which are sequentially connected through a pipeline, wherein the pipeline is used for one-way soil transportation; a heat conduction circulation groove is arranged on the outer ring of the heating oxidation pond, a heat source is arranged in the heat conduction circulation groove, and the heat source provides circulation power and heating for a heat conduction medium in the heat conduction circulation groove; the primary thickening tank is respectively provided with a lower layer clear liquid outlet and an upper layer clear liquid outlet and is respectively communicated to the coagulating sedimentation tank and the leaching stirring tank; and the water outlets of the secondary thickening tank and the plate-and-frame filter press are communicated to the coagulating sedimentation tank. The invention has the beneficial effects that a set of complete heavy metal mercury leaching and sewage treatment recycling system is established, the high-concentration mercury in the actual soil is leached efficiently, and the removal rate can reach 70%.
Description
Technical Field
The invention relates to the field of leaching treatment of heavy metal contaminated soil, in particular to a leaching system and method for mercury contaminated soil.
Background
Heavy metals in soil are an important source of soil pollution, the current physical and chemical methods for repairing the heavy metal pollution in the soil mainly comprise technologies such as chemical leaching, solidification stabilization, thermal desorption and the like, but with the concern of human beings on the environmental quality, the requirements and indexes of the corresponding environmental pollution repair are further improved, the solidification stabilization is used as a common means for passivating the heavy metals, the heavy metals in the soil are not really removed, the potential hidden danger of the solidification stabilization gradually limits the application of the solidification stabilization, and the chemical leaching has excellent market potential for energy consumption compared with the thermal desorption technology and is widely applied.
Compared with other heavy metals, mercury is limited in chemical leaching, cannot be removed from soil by common leaching agents, consumes a large amount of reagents, solvents, leaching time and the like, and is severely limited in application in leaching. Chinese patent (CN101362145) discloses a leaching method for realizing various heavy metals including mercury in soil by utilizing distributed leaching of Na2EDTA, oxalic acid and potassium iodide, but the method has low mercury removal rate in application. In order to improve the mercury removal efficiency, the patent with the application number of CN201710702248.6 utilizes oxidation and multi-stage leaching to improve the mercury leaching removal by more than 90%, but the method has higher cost, sodium sulfide used in the second-stage leaching is a dangerous chemical, and has potential risk in practical application, and the damage to soil is larger when sodium hydroxide is added to leach the soil. In this case, the original concentration of mercury in soil is much lower than the original concentration of mercury in actual industrial polluted soil and the first-level mercury standard of the soil pollution risk control standard of construction land, and in practical application, various optimization and attempts are needed.
Therefore, a feasible method which has no health risk to operators is still lacked in engineering practice for removing mercury in soil.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, solve the problem of mercury pollution removal in soil and reduce the health risk to operators.
In order to achieve the aim, the invention provides a leaching system for mercury-polluted soil, which comprises a heating oxidation tank, mechanical screening equipment, a leaching stirring tank, a primary thickening tank, a clear water leaching stirring tank, a secondary thickening tank and a plate-and-frame filter press which are sequentially connected through a pipeline, wherein the pipeline is used for one-way soil transportation;
a heat conduction circulation groove is arranged on the outer ring of the heating oxidation pond, a heat source is arranged in the heat conduction circulation groove, and the heat source provides circulation power and heating for a heat conduction medium in the heat conduction circulation groove;
the primary thickening tank is respectively provided with a lower layer clear liquid outlet and an upper layer clear liquid outlet and is respectively communicated to the coagulating sedimentation tank and the leaching stirring tank; and the water outlets of the secondary thickening tank and the plate-and-frame filter press are communicated to the coagulating sedimentation tank.
And the clear water leaching and stirring tank is filled with clear water through a water pump. The heat conduction circulation groove is used for conducting heat transfer on the heating oxidation pond. Generally, the heat conduction circulation groove is arranged close to the heating oxidation pond. The specific heat source can be a heat-conducting medium inlet and outlet communicated with the boiler.
Preferably, heating pipes are arranged in the heat conduction circulation groove, the heat conduction medium flows through the heating pipes, and the heat conduction medium is high-temperature heat conduction oil; the heating pipes are further arranged in the heating oxidation pond, and a soil stirrer is arranged outside the heating pipes in the heating oxidation pond.
The heating and stirring are simultaneously carried out in the heating oxidation pond.
Preferably, the mechanical screening device is a drum screening machine.
The drum screening machine provides certain stirring, crushing function when screening, and the cooperation adds the thermal oxidation pond, has further promoted the utilization ratio of soil.
Preferably, the leaching and stirring tank, the first-stage thickening tank and the second-stage thickening tank are in a sealed state respectively.
The leaching process of the mercury-contaminated soil is also provided, and the leaching system is adopted, and comprises the following steps:
the first step is as follows: temporarily storing the mercury polluted soil in a heating oxidation pond, and adding an oxidant to perform oxidation and heating pretreatment;
the second step is that: screening the oxidized and heated pretreated soil in mechanical screening equipment, and conveying small particles with the particle size below a set particle size to a leaching stirring pool;
the third step: carrying out chemical leaching on the separated soil in the leaching stirring tank, fully reacting, and then conveying the formed slurry into a first-stage thickening tank for separation;
the fourth step: conveying the lower layer slurry subjected to solid-liquid separation in the first-stage thickening tank to a clear water leaching and stirring tank for leaching, recycling the top layer part of the supernatant to the leaching and stirring tank, and extracting the lower layer part of the supernatant to enter a coagulating sedimentation tank;
the fifth step: guiding the slurry after the clean water in the clean water leaching and stirring tank is leached into a secondary thickening tank, transporting the supernatant in the secondary thickening tank to the coagulating sedimentation tank, and outputting the lower slurry to a plate-and-frame filter press for dewatering;
and a sixth step: the filtrate after filter pressing by the plate-and-frame filter press is transported to the coagulating sedimentation tank; and the solid compacted body after filter pressing by the plate and frame filter press is the repaired soil and is filled to a target position for maintenance.
Generally, the set particle size of the small particles may be about 1mm, ensuring the crushing possibility and the relatively large specific surface area.
Preferably, after the soil remediation is finished, adding an oxidant into the coagulating sedimentation tank, covering and sealing the coagulating sedimentation tank, and waiting for the reaction to be finished; and (3) after the reaction is finished and the precipitate in the coagulating sedimentation tank is dehydrated, treating the precipitate as hazardous waste.
The coagulating sedimentation tank is mainly used as a water treatment storage unit, and substances in the coagulating sedimentation tank can be reused as appropriate after being innoxious.
Preferably, the oxidant is sodium sulfate and citric acid solution, the concentration range of the sodium sulfate of the oxidant is 1% -4%, and the concentration range of the citric acid of the oxidant is 0.1-0.5 mol/L; and the oxidation retention time in the heating oxidation pond is 15-30 minutes.
Preferably, the eluting agent put into the eluting and stirring tank is a cysteine solution.
Preferably, the concentration range of cysteine in the eluting agent is 0.01-0.1 mol/L; and the rinsing and stirring residence time in the rinsing and stirring tank is 2-3 hours.
All the used medicaments including sodium persulfate, citric acid and cysteine are environment-friendly medicaments, so that secondary pollution to the environment is avoided, and the medicament is non-toxic and low in health risk to operators. Through proportion blending and setting of retention time of leaching stirring, the dosage of cysteine is optimized, and the cost is relatively reduced.
Preferably, the volume ratio of the first-stage thickening tank to the leaching stirring tank is 1: 2-5.
The matching volume ratio of the first-stage thickening tank and the leaching and stirring tank ensures that the first-stage thickening tank and the leaching and stirring tank can conveniently and continuously operate.
By arranging the heating oxidation pond, a proper reaction environment is provided for mercury pollution in soil, a foundation is laid for subsequent treatment of the soil, and on the other hand, the heated and oxidized soil is more loose and is convenient for subsequent screening; and the mechanical screening equipment further increases the reaction area of the polluted soil and improves the reaction efficiency in leaching. The closed environment of the pipeline can also keep the soil heat at the proper reaction temperature in the whole process as far as possible.
The soil in the heating oxidation pond is stirred, so that the massive soil is damaged, and the utilization rate of the soil is improved.
By setting the reaction cell in a sealed state without communicating with the atmospheric environment, it is possible to prevent mercury-containing compounds or other substances from sublimating during the reaction.
The transfer of the lower layer mud, the supernatant liquid top layer part and the supernatant liquid lower layer part in the first-stage thickening tank provides a foundation for reasonable utilization of leaching resources, and avoids mutual re-pollution as far as possible.
The invention has the beneficial effects that a set of complete heavy metal mercury leaching and sewage treatment recycling process is established, the high-concentration mercury in the actual soil is leached efficiently, and the removal rate can reach 70%.
Drawings
FIG. 1 is a schematic view of the overall structure of a mercury contaminated soil leaching system according to the present invention;
fig. 2 is a schematic view of the heating oxidation cell in the leaching system of the present invention;
wherein:
1-heat source 2-heating oxidation tank 21-heat conduction circulation channel
3-mechanical screening equipment 4-leaching stirring tank 5-first-stage thickening tank
6-clear water leaching and stirring tank 7-second-stage thickening tank 8-plate and frame filter press
9-soil stirrer 10-coagulating sedimentation tank
Detailed Description
The invention is further described below with reference to the following figures and specific examples.
The leaching system for mercury contaminated soil shown in fig. 1 to 2 comprises a heating oxidation tank 2, a drum screening type mechanical screening device 3, a leaching stirring tank 4, a primary thickening tank 5, a clear water leaching stirring tank 6, a secondary thickening tank 7 and a plate-and-frame filter press 8 which are sequentially connected through pipelines, wherein the pipelines are used for one-way soil transportation;
a heat conduction circulation groove 21 is arranged outside the heating oxidation pond 2, a heat source 1 is arranged in the heat conduction circulation groove 21, and the heat source 1 provides circulation power and heating for a heat conduction medium in the heat conduction circulation groove 21;
the primary thickening tank 5 is respectively provided with a lower layer clear liquid outlet and an upper layer clear liquid outlet and is respectively communicated with the coagulating sedimentation tank 10 and the leaching stirring tank 4; the water outlets of the secondary thickening tank 7 and the plate-and-frame filter press 8 are communicated to the coagulating sedimentation tank 10.
Heating pipes are arranged in the heat conduction circulation groove 21, the heat conduction medium flows through the heating pipes, and the heat conduction medium is high-temperature heat conduction oil; the heating pipes are further arranged in the heating oxidation pond 2, and a soil stirrer 9 is arranged outside the heating pipes in the heating oxidation pond 2.
The leaching and stirring tank 4, the first-stage thickening tank 5 and the second-stage thickening tank 7 are in a sealed state respectively.
According to the leaching process of the mercury-contaminated soil shown in fig. 1, the leaching system is adopted, and the leaching process comprises the following steps:
the first step is as follows: temporarily storing the mercury polluted soil in a heating oxidation pond 2, and adding an oxidant to carry out oxidation and heating pretreatment;
the second step is that: screening the oxidized and heated pretreated soil in a mechanical screening device 3, and conveying small particles with the particle size of less than 1mm to a leaching stirring tank 4;
the third step: carrying out chemical leaching on the separated soil in the leaching and stirring tank 4, fully reacting, and then conveying the formed slurry into a first-stage thickening tank 5 for separation;
the fourth step: the lower layer slurry after solid-liquid separation in the first-stage thickening tank 5 is transported to a clear water leaching and stirring tank for leaching 6, the top layer part of the supernatant is recycled to the leaching and stirring tank 4, and the lower layer part of the supernatant is extracted and enters a coagulating sedimentation tank 10;
the fifth step: guiding the slurry after the clean water is washed in the clean water washing and stirring tank 6 into a secondary thickening tank 7, transporting the supernatant in the secondary thickening tank 7 to the coagulating sedimentation tank 10, and outputting the lower slurry to a plate-and-frame filter press 8 for dewatering;
and a sixth step: the filtrate after filter pressing by the plate-and-frame filter press 8 is transported to the coagulating sedimentation tank 10; and the solid compacted body after filter pressing by the plate and frame filter press 8 is the repaired soil and is filled to a target position for maintenance.
After the soil remediation is finished, adding an oxidant into the coagulating sedimentation tank 10, covering and sealing the coagulating sedimentation tank 10, and waiting for the completion of the reaction; and the precipitate in the coagulating sedimentation tank 10 is treated as hazardous waste after the reaction is finished and the precipitate is dehydrated.
The oxidant is sodium sulfate and citric acid solution, the concentration range of the sodium sulfate of the oxidant is 1% -4%, and the concentration range of the citric acid of the oxidant is 0.1-0.5 mol/L; and the oxidation retention time in the heating oxidation pond 2 is 15-30 minutes. The eluting agent put into the eluting and stirring tank 4 is cysteine solution. The concentration range of cysteine of the eluting agent is 0.01-0.1 mol/L; and the rinsing and stirring residence time in the rinsing and stirring tank 4 is 2-3 hours. The volume ratio of the first-stage thickening tank 5 to the leaching stirring tank 4 is 1: 2-5.
In practical use, the external exposed area of the heating pipe in the heating oxidation pond 2 is nine square meters. The existing mercury-contaminated soil is adopted for carrying out experiment data acquisition:
experiment one: the mercury pollution in the soil of a certain polluted land block in suburb areas of Shanghai city is serious, the soil is sampled, and the polluted soil is leached by adopting the leaching system and the leaching process of the mercury polluted soil.
1. Analysis of each index of polluted original soil
TABLE 1 original soil sampling concentration (mg/kg) of contaminated soil
2. Polluted soil treatment process and condition
Specifically, the added medicaments are respectively sodium persulfate as an oxidant, citric acid and eluent cysteine, and the concentrations of the added medicaments are respectively 4%, 0.2mol/L and 0.1 mol/L. The oxidation time is 30min, and the chemical leaching time is 3 h.
3. Application results
TABLE 2 concentration (mg/kg) and removal rate of each heavy metal in the soil after leaching treatment
| Heavy metals | | Sample | 1 | |
Sample 3 | |
Mean value of | Total removal rate |
| Cu | 1544 | 511 | 529 | 505 | 506 | 513 | 67％ | |
| Pb | 146 | 32 | 37 | 30 | 41 | 35 | 76％ | |
| As | 34 | 15 | 12 | 15 | 9 | 13 | 62％ | |
| Hg | 55 | 20 | 21 | 20 | 19 | 20 | 64％ |
In conclusion, after the system and the method are adopted, the mercury in the soil is reduced from 55mg/kg to 20mg/kg, the removal rate is 64 percent, and the effective removal of high-concentration mercury is realized. In addition, Cu, Pb and As can be effectively removed, and the removal rates are 67%, 76% and 62% respectively.
Experiment two: the mercury in the soil of a certain polluted land block in suburb areas of Shanghai city slightly pollutes, the soil is sampled, and the polluted soil is leached by adopting the treatment system and the treatment process of the mercury-polluted soil.
1. Analysis of each index of polluted original soil
TABLE 3 original soil sampling concentration (mg/kg) of contaminated soil
| | Sample | 1 | |
Sample 3 | |
Average value of C1 |
| Pb | 2410 | 2452 | 2605 | 2550 | 2504 | |
| As | 111 | 124 | 133 | 117 | 121 | |
| Hg | 14 | 18 | 15 | 12 | 15 |
2. Polluted soil treatment process and condition
Specifically, the added medicaments are respectively sodium persulfate as an oxidant, citric acid and eluent cysteine, and the concentrations of the added medicaments are respectively 1%, 0.1mol/L and 0.01 mol/L. The oxidation time is 15min, and the chemical leaching time is 2 h.
3. Application results
TABLE 4 concentration (mg/kg) and removal rate of each heavy metal in the soil after washing treatment
| Heavy metals | | Sample | 1 | |
Sample 3 | |
Average value of C2 | Removal rate |
| Pb | 2504 | 2284 | 2293 | 2373 | 2444 | 2348.5 | 6％ | |
| As | 121 | 114 | 112 | 109 | 106 | 110.25 | 9％ | |
| Hg | 15 | 4 | <4 | <4 | <4 | 4 | 73％ |
In conclusion, after the system and the method are adopted in the second experiment, the mercury in the soil is reduced to below 4mg/kg from 15mg/kg, the removal rate is 73%, and the effective removal of high-concentration mercury is realized. In addition, both Pb and As can be effectively removed, and the removal rate is respectively 6% and 9%.
While the preferred embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that the invention is not limited to the embodiments disclosed, but is capable of numerous equivalents and substitutions, all of which are within the scope of the invention as defined by the appended claims.
Claims (10)
1. The leaching system for the mercury-polluted soil is characterized by comprising a heating oxidation tank, mechanical screening equipment, a leaching stirring tank, a primary thickening tank, a clear water leaching stirring tank, a secondary thickening tank and a plate-and-frame filter press which are sequentially connected through a pipeline, wherein the pipeline is used for one-way soil transportation;
a heat conduction circulation groove is arranged on the outer ring of the heating oxidation pond, a heat source is arranged in the heat conduction circulation groove, and the heat source provides circulation power and heating for a heat conduction medium in the heat conduction circulation groove;
the primary thickening tank is respectively provided with a lower layer clear liquid outlet and an upper layer clear liquid outlet and is respectively communicated to the coagulating sedimentation tank and the leaching stirring tank; and the water outlets of the secondary thickening tank and the plate-and-frame filter press are communicated to the coagulating sedimentation tank.
2. The leaching system according to claim 1, wherein heating pipes are arranged in the heat conduction circulation groove, the heat conduction medium circulates in the heating pipes, and the heat conduction medium is high-temperature heat conduction oil; the heating pipes are further arranged in the heating oxidation pond, and a soil stirrer is arranged outside the heating pipes in the heating oxidation pond.
3. The washing system according to claim 1, wherein the mechanical screening device is a drum screen.
4. The leaching system according to claim 1, wherein the leaching agitation tank is sealed from the first-stage thickening tank and the second-stage thickening tank.
5. The leaching process of the mercury-contaminated soil is characterized in that the leaching system of any one of claims 1 to 4 is adopted, and the leaching process comprises the following steps:
the first step is as follows: temporarily storing the mercury polluted soil in a heating oxidation pond, and adding an oxidant to perform oxidation and heating pretreatment;
the second step is that: screening the oxidized and heated pretreated soil in mechanical screening equipment, and conveying small particles with the particle size below a set particle size to a leaching stirring pool;
the third step: carrying out chemical leaching on the separated soil in the leaching stirring tank, fully reacting, and then conveying the formed slurry into a first-stage thickening tank for separation;
the fourth step: conveying the lower layer slurry subjected to solid-liquid separation in the first-stage thickening tank to a clear water leaching and stirring tank for leaching, recycling the top layer part of the supernatant to the leaching and stirring tank, and extracting the lower layer part of the supernatant to enter a coagulating sedimentation tank;
the fifth step: guiding the slurry after the clean water in the clean water leaching and stirring tank is leached into a secondary thickening tank, transporting the supernatant in the secondary thickening tank to the coagulating sedimentation tank, and outputting the lower slurry to a plate-and-frame filter press for dewatering;
and a sixth step: the filtrate after filter pressing by the plate-and-frame filter press is transported to the coagulating sedimentation tank; and the solid compacted body after filter pressing by the plate and frame filter press is the repaired soil and is filled to a target position for maintenance.
6. The leaching process according to claim 5, wherein after the soil remediation is completed, an oxidant is added into the coagulation sedimentation tank, the coagulation sedimentation tank is covered and sealed, and the reaction is waited for completion; and (3) after the reaction is finished and the precipitate in the coagulating sedimentation tank is dehydrated, treating the precipitate as hazardous waste.
7. The leaching process according to any one of claims 5 or 6, wherein the oxidizing agent is sodium sulfate-citric acid solution, the sodium sulfate concentration of the oxidizing agent is in the range of 1% to 4%, and the citric acid concentration of the oxidizing agent is in the range of 0.1 to 0.5 mol/L; and the oxidation retention time in the heating oxidation pond is 15-30 minutes.
8. The washing process according to claim 5, wherein the washing agent fed into the washing agitation tank is a cysteine solution.
9. The leaching process according to claim 8, wherein the concentration of cysteine in the leaching agent is in the range of 0.01-0.1 mol/L; and the rinsing and stirring residence time in the rinsing and stirring tank is 2-3 hours.
10. The leaching process according to claim 5, wherein the volume ratio of the first-stage thickening tank to the leaching stirring tank is 1: 2-5.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011307657.4A CN112718837A (en) | 2020-11-20 | 2020-11-20 | Leaching system and process for mercury-polluted soil |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011307657.4A CN112718837A (en) | 2020-11-20 | 2020-11-20 | Leaching system and process for mercury-polluted soil |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112718837A true CN112718837A (en) | 2021-04-30 |
Family
ID=75597622
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011307657.4A Pending CN112718837A (en) | 2020-11-20 | 2020-11-20 | Leaching system and process for mercury-polluted soil |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112718837A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115945510A (en) * | 2022-12-23 | 2023-04-11 | 中科鼎实环境工程有限公司 | Heavy metal pollution purification device and purification method applied to farmland |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1043082A2 (en) * | 1999-03-30 | 2000-10-11 | Interpole Limited | Method for soil decontamination |
| TWI285138B (en) * | 2006-03-29 | 2007-08-11 | Hung Jiang | Method for separating mercury and cracking dioxin and organic substance with high temperature vapor and recycled heat source |
| KR100958550B1 (en) * | 2009-04-22 | 2010-05-18 | 주식회사 윈텍에이티에스 | Soil restoration apparatus |
| JP2011190428A (en) * | 2010-02-17 | 2011-09-29 | Univ Of Tsukuba | Remover composition for heavy metal in soil, and method for removing heavy metal using the same |
| CN105834205A (en) * | 2016-06-03 | 2016-08-10 | 上海格林曼环境技术有限公司 | In-situ electric heating desorption restoration technology and device for contaminated site |
| CN105983571A (en) * | 2016-06-30 | 2016-10-05 | 无锡市太湖湖泊治理有限责任公司 | Polluted soil repairing system |
| CN109500074A (en) * | 2018-12-27 | 2019-03-22 | 上海市环境科学研究院 | Dystopy suitable for clayed soil pollution amelioration elutes prosthetic device and restorative procedure |
| CN111408612A (en) * | 2019-01-07 | 2020-07-14 | 天津生态城环保有限公司 | Engineering remediation method for soil polluted by cyanide |
-
2020
- 2020-11-20 CN CN202011307657.4A patent/CN112718837A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1043082A2 (en) * | 1999-03-30 | 2000-10-11 | Interpole Limited | Method for soil decontamination |
| TWI285138B (en) * | 2006-03-29 | 2007-08-11 | Hung Jiang | Method for separating mercury and cracking dioxin and organic substance with high temperature vapor and recycled heat source |
| KR100958550B1 (en) * | 2009-04-22 | 2010-05-18 | 주식회사 윈텍에이티에스 | Soil restoration apparatus |
| JP2011190428A (en) * | 2010-02-17 | 2011-09-29 | Univ Of Tsukuba | Remover composition for heavy metal in soil, and method for removing heavy metal using the same |
| CN105834205A (en) * | 2016-06-03 | 2016-08-10 | 上海格林曼环境技术有限公司 | In-situ electric heating desorption restoration technology and device for contaminated site |
| CN105983571A (en) * | 2016-06-30 | 2016-10-05 | 无锡市太湖湖泊治理有限责任公司 | Polluted soil repairing system |
| CN109500074A (en) * | 2018-12-27 | 2019-03-22 | 上海市环境科学研究院 | Dystopy suitable for clayed soil pollution amelioration elutes prosthetic device and restorative procedure |
| CN111408612A (en) * | 2019-01-07 | 2020-07-14 | 天津生态城环保有限公司 | Engineering remediation method for soil polluted by cyanide |
Non-Patent Citations (2)
| Title |
|---|
| 何振立: "《污染及有益元素的土壤化学平衡》", 30 June 1998, 中国环境科学出版社 * |
| 范拴喜: "《土壤重金属污染与控制》", 30 November 2011, 中国环境科学出版社 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115945510A (en) * | 2022-12-23 | 2023-04-11 | 中科鼎实环境工程有限公司 | Heavy metal pollution purification device and purification method applied to farmland |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103316907B (en) | Heavy-metal-polluted site soil leaching remediation method and device | |
| CN105884157A (en) | Method for removing and recovering heavy metal in sludge through electrolytic method | |
| CN104190701A (en) | Leaching method for remediation of arsenic polluted soil by using magnetic separation | |
| CN105174577B (en) | A kind of coal chemical industrial waste water pretreating process and device | |
| CN101708501A (en) | Two-stage countercurrent washing medicament addition stabilization combined restoration method of chromium polluted soil | |
| CN109013683A (en) | A kind of soil restoring device by heavy-metal contaminated soil | |
| CN103183459A (en) | Method for removing heavy metal from sludge of sewage treatment works | |
| CN101514037A (en) | Method for removing low-concentration heavy metal in waste water by sludge absorption | |
| CN108579669A (en) | For the regenerated regenerative agent of heavy-metal contaminated soil ring waste and preparation method and application | |
| CN102583916A (en) | Method for removing heavy metal from sludge | |
| CN105400959A (en) | Method and device for performing recovery and resource utilization on heavy metal in waste acid | |
| CN112718837A (en) | Leaching system and process for mercury-polluted soil | |
| CN112371714A (en) | Remediation method for treating contaminated site soil | |
| CN205528336U (en) | Mud centrifugal dehydration system is taked care of to high temperature high pressure | |
| CN104451159A (en) | Process for recycling metals from electroplating wastewater | |
| CN103803682A (en) | Method for preparing iron composite filler loaded with carbon nanotube | |
| CN215089741U (en) | Leaching restoration line for mercury-contaminated soil | |
| CN109622583A (en) | A kind of method heavy-metal contaminated soil ring waste regeneration and recycled | |
| CN211079293U (en) | Nickel hydroxide cobalt sediment leaches device | |
| CN108193052A (en) | Resource utilization prepares the method without ammonium fluxing agent using low acid waste water containing zinc | |
| Sabia et al. | Treatment and management of the effluents generated by hydrometallurgical processes applied to End-of-Life Photovoltaic Panels | |
| CN112718838A (en) | Leaching system and process for high-concentration copper-polluted soil | |
| CN206661920U (en) | The processing unit of uranium contaminated soil is repaired in reduction | |
| CN211595332U (en) | System for treating coke oven gas desulfurization and decyanation waste liquid by using waste pickling solution | |
| CN104876365A (en) | High-concentration cyanogen-contained tailing slurry treatment method for gold industry |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210430 |