CN116371893A - System and method for strengthening water washing and dechlorination effects of fly ash and reducing leaching toxicity of heavy metal - Google Patents
System and method for strengthening water washing and dechlorination effects of fly ash and reducing leaching toxicity of heavy metal Download PDFInfo
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- 238000005406 washing Methods 0.000 title claims abstract description 159
- 239000010881 fly ash Substances 0.000 title claims abstract description 133
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 90
- 229910001385 heavy metal Inorganic materials 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 32
- 238000002386 leaching Methods 0.000 title claims abstract description 28
- 230000000694 effects Effects 0.000 title claims abstract description 17
- 230000001988 toxicity Effects 0.000 title claims abstract description 17
- 231100000419 toxicity Toxicity 0.000 title claims abstract description 17
- 238000006298 dechlorination reaction Methods 0.000 title claims abstract description 15
- 238000005728 strengthening Methods 0.000 title abstract description 6
- 239000007788 liquid Substances 0.000 claims abstract description 76
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 72
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 36
- 239000002699 waste material Substances 0.000 claims abstract description 35
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 18
- 238000012544 monitoring process Methods 0.000 claims abstract description 11
- 239000000126 substance Substances 0.000 claims abstract description 8
- 239000000203 mixture Substances 0.000 claims abstract description 7
- 239000002253 acid Substances 0.000 claims description 12
- 230000002708 enhancing effect Effects 0.000 claims description 12
- 238000001514 detection method Methods 0.000 claims description 9
- QPILZZVXGUNELN-UHFFFAOYSA-M sodium;4-amino-5-hydroxynaphthalene-2,7-disulfonate;hydron Chemical compound [Na+].OS(=O)(=O)C1=CC(O)=C2C(N)=CC(S([O-])(=O)=O)=CC2=C1 QPILZZVXGUNELN-UHFFFAOYSA-M 0.000 claims description 9
- 238000005554 pickling Methods 0.000 claims description 8
- 238000000926 separation method Methods 0.000 claims description 8
- 238000004364 calculation method Methods 0.000 claims description 7
- 150000003841 chloride salts Chemical class 0.000 claims description 6
- 238000002360 preparation method Methods 0.000 claims description 6
- 238000012545 processing Methods 0.000 claims description 6
- 238000001784 detoxification Methods 0.000 claims description 4
- 230000001376 precipitating effect Effects 0.000 claims description 3
- 239000002002 slurry Substances 0.000 claims description 3
- 239000003153 chemical reaction reagent Substances 0.000 claims description 2
- 239000003795 chemical substances by application Substances 0.000 claims description 2
- 238000001704 evaporation Methods 0.000 claims description 2
- 238000010979 pH adjustment Methods 0.000 claims description 2
- 238000005660 chlorination reaction Methods 0.000 claims 3
- 125000001309 chloro group Chemical class Cl* 0.000 claims 1
- 238000004846 x-ray emission Methods 0.000 claims 1
- 238000004876 x-ray fluorescence Methods 0.000 abstract description 6
- 230000001105 regulatory effect Effects 0.000 abstract description 3
- 230000007613 environmental effect Effects 0.000 abstract description 2
- 238000010183 spectrum analysis Methods 0.000 abstract description 2
- QPILZZVXGUNELN-UHFFFAOYSA-N sodium;4-amino-5-hydroxynaphthalene-2,7-disulfonic acid Chemical compound [Na+].OS(=O)(=O)C1=CC(O)=C2C(N)=CC(S(O)(=O)=O)=CC2=C1 QPILZZVXGUNELN-UHFFFAOYSA-N 0.000 abstract 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 8
- 229910052801 chlorine Inorganic materials 0.000 description 8
- 239000000460 chlorine Substances 0.000 description 8
- 230000001276 controlling effect Effects 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- 239000002351 wastewater Substances 0.000 description 5
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- 238000009616 inductively coupled plasma Methods 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 229910019142 PO4 Inorganic materials 0.000 description 2
- 150000001804 chlorine Chemical class 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000010813 municipal solid waste Substances 0.000 description 2
- 239000010452 phosphate Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 238000010936 aqueous wash Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012806 monitoring device Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000029219 regulation of pH Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 238000004056 waste incineration Methods 0.000 description 1
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- 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
- B09B3/70—Chemical treatment, e.g. pH adjustment or oxidation
-
- 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
- B09B3/40—Destroying solid waste or transforming solid waste into something useful or harmless involving thermal treatment, e.g. evaporation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B2101/00—Type of solid waste
- B09B2101/30—Incineration ashes
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Health & Medical Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Analysing Materials By The Use Of Radiation (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention belongs to the technical field of environmental protection, and relates to a system and a method for strengthening the water washing and dechlorination effects of fly ash and reducing the leaching toxicity of heavy metals. The method and the system are as follows: detecting the composition of fly ash substances through X-ray fluorescence spectrum analysis and calculating the neutralization capacity of fly ash acid; calculating the phosphoric acid addition amount of the water washing liquid according to the neutralization capacity of the fly ash acid and preparing phosphoric acid water washing liquid; and (3) washing the fly ash by using phosphoric acid washing liquid, and adjusting the end-point pH value of the washing system through pH value monitoring and regulating equipment in the washing process. The invention can strengthen the water washing and dechlorination effect of the fly ash, and simultaneously reduce the leaching of heavy metals in the fly ash in the water washing process, thereby reducing the heavy metal content in the water washing waste liquid and saving the treatment cost of the water washing liquid.
Description
Technical Field
The invention belongs to the technical field of environmental protection, and relates to a system and a method for strengthening the water washing and dechlorination effects of fly ash and reducing the leaching toxicity of heavy metals.
Background
The disclosure of this background section is only intended to increase the understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art already known to those of ordinary skill in the art.
According to research of the inventor, the heavy metal in the fly ash of municipal solid waste incineration can be leached into the water washing liquid in the process of water washing and dechlorination, so that the heavy metal content in the water washing liquid is high, and the subsequent treatment cost of the water washing liquid is increased.
Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide a system and a method for strengthening the water-washing and dechlorination effects of fly ash and effectively reducing the leaching toxicity of heavy metals, which can reduce the leaching of the heavy metals in the fly ash while strengthening the water-washing and dechlorination effects of the fly ash, thereby reducing the concentration of the heavy metals in the water-washing waste liquid and saving the treatment cost of the water-washing waste liquid.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
in a first aspect of the invention, there is provided a method of enhancing the water-wash-out of fly ash and reducing the leaching toxicity of heavy metals comprising:
detecting the composition of the fly ash substances and calculating the neutralization capacity of fly ash acid;
calculating the phosphoric acid addition amount of the water washing liquid according to the neutralization capacity of the fly ash acid and preparing phosphoric acid water washing liquid;
the method comprises the steps of (1) washing fly ash by using phosphoric acid washing liquid, monitoring the pH value in the washing process, and adjusting the pH value range of a water washing system end point to 7+/-1;
after the water washing is finished, carrying out solid-liquid separation on the slurry mixture obtained by the water washing, and respectively collecting fly ash and water washing waste liquid;
adding an organic precipitant or an inorganic reagent into the washing waste liquid, precipitating and separating heavy metals in the washing liquid, and collecting the detoxified washing waste liquid;
and (3) evaporating the detoxified water washing waste liquid with high efficiency, and recovering chlorine salt and water to obtain the water-washing waste liquid.
In a second aspect of the invention, there is provided a system for enhancing the water-wash-out of fly ash and reducing the leaching toxicity of heavy metals, comprising: the device comprises a fly ash component detection device, a data processing device, a pickling solution preparation device, a water washing device, a dynamic detection and adjustment pH device, a solid-liquid separation device, a detoxification device and a high-efficiency evaporator;
the pickling solution preparation device is sequentially connected with the water washing device, the solid-liquid separation device, the detoxification device and the high-efficiency evaporator;
the washing device is also connected with a dynamic detection and pH adjustment device;
the data processing apparatus includes: a module for calculating the neutralization capacity of fly ash acid and a module for calculating the acid addition amount; the data processing device is respectively connected with the fly ash component detection device and the pickling solution preparation device,
the module for calculating the neutralization capacity of the fly ash acid, the module for calculating the acid adding amount and the pickling solution configuration device are automatically controlled by a PLC.
In a third aspect of the invention, there is provided the use of a phosphoric acid solution to wash out partially insoluble and insoluble chloride salts in fly ash.
The beneficial effects of the invention are that
(1) According to the invention, phosphoric acid is added into the washing unit to control the pH value of the end point of the washing system, so that leaching of heavy metals in fly ash is reduced, phosphate radicals can form phosphate precipitation with heavy metal ions, and the concentration of the heavy metals in the washing waste liquid is further reduced.
(2) The invention uses phosphoric acid solution as water washing liquid, and the addition of phosphoric acid can wash out partial indissolvable and insoluble chloride (Friedel's salt) in fly ash while reducing the concentration of heavy metal in the water washing waste liquid, thereby improving the washing rate of the chloride.
(3) The concentration of heavy metals in the water washing wastewater generated by the method is low, so that the subsequent heavy metal treatment cost is reduced, and the purity of the recovered chloride salt is improved.
(4) Compared with the traditional method for optimizing the pH value of the end point of the heavy metal leaching liquid of the fly ash, the method has the advantages that the pH value of a water washing system is dynamically adjusted in a specific water washing section, so that the pH value is always in a preset pH value range, the heavy metal content in the fly ash water washing liquid is effectively reduced, and the washing rate of chloride salt is improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.
FIG. 1 is a conceptual plot of the behavior of heavy metals dissolved in fly ash at various endpoint pH values;
FIG. 2 shows a system flow for enhancing the water-wash-out effect of fly ash and reducing the leaching toxicity of heavy metals.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
After the household garbage is incinerated, tiny particles generated by the flue gas through dust removal equipment are fly ash, and a large amount of chloride and heavy metals are contained in the fly ash. In the process of water washing and dechlorination of the fly ash, heavy metals can leach into the water washing liquid.
In view of the problems of high heavy metal content and high treatment cost in the fly ash washing waste liquid, the invention provides a method for reducing the heavy metal content in the fly ash washing liquid by controlling the end-point pH value of a washing system.
In one aspect, a method for reducing leaching of heavy metals in fly ash by controlling the endpoint pH of a water wash system by formulating a phosphoric acid aqueous wash solution.
In the water washing process, the leaching behavior of heavy metals in the fly ash is related to the end point pH value of the water washing system. The leaching behaviour of the different heavy metals is different and corresponds to one of three leaching behaviour patterns (cationic, oxyanionic, amphoteric) as shown in figure 1. Wherein the content of the amphoteric leaching mode metals (Pb and Zn) in the fly ash is high, the leaching amount is large, and the concentration in the washing waste liquid easily exceeds the discharge concentration limit value of the integrated wastewater discharge standard (GB 8978-1996). Therefore, pb and Zn are focused when considering the end point pH value range of the washing liquid, and finally, the optimal end point pH value range of the washing liquid in practical application is determined to be 7+/-1.
And taking a fly ash sample before washing, and performing X-ray fluorescence spectrum analysis to obtain fly ash substance component data. The acid neutralization capacity and the acid adding amount of the fly ash are automatically calculated by inputting the fly ash substance component data into the program, and the phosphoric acid is automatically and quantitatively added into the washing liquid according to the calculation result, so that the purpose of controlling the end point pH value of the washing system is achieved. Wherein, the automatic calculation of the adding amount of the phosphoric acid and the adding of the phosphoric acid into the water washing liquid are realized by a Programmable Logic Controller (PLC).
On the other hand, the method for monitoring and controlling the pH value of the water washing system in real time in the water washing process is provided. And adding a pH value real-time monitoring device into the water washing unit, and automatically adding fly ash (when the pH value of the system is less than 6) or phosphoric acid (when the pH value of the system is more than 8) to adjust the pH value of the water washing system when the pH value exceeds a preset range.
After the water washing is finished, solid-liquid separation is carried out on the slurry mixture obtained by the water washing, the fly ash obtained by separation is output, and the water washing waste liquid enters a water washing waste liquid treatment unit. The washing waste liquid treatment unit firstly adds TMT-102, MT-103, RS-2568 and other organic precipitants or Na into the washing waste liquid 2 S、Na 2 CO 3 、FeSO 4 、Ca 3 (PO 4 ) 2 And inorganic agents, and precipitating and separating heavy metals in the water washing liquid. And then the detoxified washing waste liquid is efficiently evaporated and crystallized to recover chlorine salt and water. The recovered water can be used for washing fly ash continuously or discharged after reaching the standard.
The mechanism for controlling the end point pH value of the water washing system is that the H which is required to be consumed by the fly ash when the pH value of the system is 7 can be calculated by calculating the acid neutralization capacity of the fly ash + Thereby calculating the required quality of phosphoric acid.
Only the main substances in the fly ash which can participate in the calculation of the acid neutralization capacity are considered, and assuming that the alkaline substances and the acidic substances in the fly ash are all neutralized, the theoretical calculation formula of the fly ash Acid Neutralization Capacity (ANC) is as follows:
wherein ANC is the value of the acid neutralization capacity of fly ash;
is Al in fly ash 2 O 3 Mass fraction (%);
is Fe in fly ash 2 O 3 Mass fraction (%); omega CaO The mass fraction (%) of CaO in fly ash; omega MgO The mass fraction (%) of MgO in fly ash; />
Is K in fly ash 2 Mass fraction (%) of O; />
Is Na in fly ash 2 Mass fraction (%) of O; />
Is SO in fly ash 3 Mass fraction (%); />
Is P in fly ash 2 O 5 Mass fraction (%).
When the amount of phosphoric acid to be added is calculated, assuming complete electrolysis of phosphoric acid in water, if the final pH of the water-washing system is set to 7, the phosphoric acid is electrolyzed to H + The amount of material of (2) needs to be numerically equal to the ANC of the fly ash. The mass of phosphoric acid required to be consumed per gram of fly ash is calculated as follows:
wherein m is the mass of phosphoric acid (g) required to be consumed per gram of fly ash; ANC is a numerical value of the acid neutralization capacity of fly ash.
Integrating the two formulas and converting the formulas in units to obtain the mass of phosphoric acid required to be added per kilogram of fly ash:
wherein m is the mass of phosphoric acid (kg) required to be consumed per kilogram of fly ash;
is Al in fly ash 2 O 3 Mass fraction (%); />
Is Fe in fly ash 2 O 3 Mass fraction (%); omega CaO The mass fraction (%) of CaO in fly ash; omega MgO The mass fraction (%) of MgO in fly ash; />
Is K in fly ash 2 Mass fraction (%) of O; />
Is Na in fly ash 2 Mass fraction (%) of O; />
Is SO in fly ash 3 Mass fraction (%); />
Is P in fly ash 2 O 5 Mass fraction (%).
In addition, the pH value of the water washing system is monitored in real time in the fly ash water washing process, and the pH value of the water washing system is automatically adjusted by adding fly ash (when the pH value of the system is less than 6) or phosphoric acid (when the pH value of the system is more than 8) so as to be within the range of 7+/-1. The pH value monitoring and adjusting system is started when the water washing time is 70%.
According to an exemplary embodiment of the invention, a method for reducing the heavy metal content in water washing waste liquid and improving the chloride salt washing rate of fly ash is provided, and the pH value of a water washing system is dynamically monitored, regulated and controlled by preparing phosphoric acid water washing liquid and the pH value of a water washing unit, so that the leaching of heavy metal in the fly ash is reduced and the chloride salt washing rate is improved;
the quality of phosphoric acid needed to be added in preparing the phosphoric acid washing liquid is obtained by the acid neutralization capacity data of fly ash and a calculation formula;
the acid neutralization capacity of the fly ash is obtained by the fly ash material composition data and a calculation formula;
the control of the pH value of the end point of the washing system is realized by preparing phosphoric acid washing liquid and monitoring and regulating equipment of the pH value of a washing unit;
in some embodiments, the fly ash and water wash liquid to solid ratio is from 3:1 to 4:1L/kg.
In some embodiments, the water wash time is 15 to 30 minutes.
In some embodiments, the water wash agitation frequency is 300 to 500r/min.
The invention will now be described in further detail with reference to the following specific examples, which should be construed as illustrative rather than limiting.
Example 1
10g of fly ash samples in a batch of fly ash are taken and dried, 5g of the dried fly ash samples are taken and analyzed for compound components by using an X-ray fluorescence spectrometer to obtain CaO and Fe 2 O 3 、Al 2 O 3 、Na 2 O、K 2 O、MgO、P 2 O 5 、SO 3 Mass fraction data (16.8%, 3.65%, 6.75%, 15.2%, 8.13%, 3.45%, 1.55%, 6.88%, respectively), data were imported into the program, and the system automatically performed the entire water washing flow. Wherein the liquid-solid ratio of the washing liquid to the fly ash is 4:1L/kg, the washing time is 25 minutes, and the washing stirring frequency is highThe rate is 400r/min, and after the water washing time exceeds 17.5 minutes, a real-time monitoring and pH value adjusting system is started to control the pH value to be within the range of 7+/-1.
After the washing, 10mL of untreated washing waste liquid was taken, and the total chlorine content was measured by using a Dynamics-1000 ion chromatograph, and the heavy metal content was measured by using an inductively coupled plasma mass spectrometer (ICP-MS). The result shows that the total chlorine removal rate of the fly ash reaches 91.87%. Compared with the traditional water washing (namely, the pH regulation is not carried out in the whole water washing process), the method reduces the Zn content in the water washing waste liquid by 82.43 percent, reduces the Pb content by 89.3 percent, reduces the Cu content by 16.93 percent and reduces the Cd content by 38.39 percent, and the concentration of the heavy metals in the water washing waste liquid does not exceed the comprehensive wastewater discharge standard (GB 8978-1996).
Example 2
Drying 10g of fly ash samples in a batch of fly ash, taking 5g of fly ash samples, and analyzing the compound components by using an X-ray fluorescence spectrometer to obtain CaO and Fe 2 O 3 、Al 2 O 3 、Na 2 O、K 2 O、MgO、P 2 O 5 、SO 3 Mass fraction data (22.54%, 2.92%, 8.01%, 15.74%, 17.56%, 2.68%, 1.26%, 5.27%, respectively) are imported into the data importing program, and the system automatically executes the whole water washing flow. Wherein, the liquid-solid ratio of the washing liquid to the fly ash is 4:1L/kg, the washing time is 20 minutes, the washing stirring frequency is 300r/min, and after the washing time exceeds 14 minutes, a real-time monitoring and pH value adjusting system is started to control the pH value to be in the range of 7+/-1.
After the washing, 10mL of untreated washing waste liquid was taken, and the total chlorine content was measured by using a Dynamics-1000 ion chromatograph, and the heavy metal content was measured by using an inductively coupled plasma mass spectrometer (ICP-MS). The result shows that the total chlorine removal rate of the fly ash reaches 90.41 percent. Compared with the traditional water washing method, the method has the advantages that the Zn content in the water washing waste liquid is reduced by 81.89 percent, the Pb content is reduced by 87.6 percent, the Cu content is reduced by 14.45 percent, the Cd content is reduced by 36.97 percent, and the concentration of the heavy metals in the water washing waste liquid does not exceed the comprehensive sewage discharge standard (GB 8978-1996).
Example 3
Drying 10g of fly ash samples in a batch of fly ash, taking 5g of fly ash samples, and analyzing the compound components by using an X-ray fluorescence spectrometer to obtain CaO and Fe 2 O 3 、Al 2 O 3 、Na 2 O、K 2 O、MgO、P 2 O 5 、SO 3 Mass fraction data (23.16%, 2.07%, 11.24%, 12.41%, 7.17%, 3.54%, 1.74%, 7.22%, respectively) were imported into the data importing program, and the system automatically executed the whole water washing flow. Wherein, the liquid-solid ratio of the washing liquid to the fly ash is 4:1L/kg, the washing time is 30 minutes, the washing stirring frequency is 500r/min, and after the washing time exceeds 21 minutes, a real-time monitoring and pH value adjusting system is started to control the pH value to be in the range of 7+/-1.
After the washing, 10mL of untreated washing waste liquid was taken, and the total chlorine content was measured by using a Dynamics-1000 ion chromatograph, and the heavy metal content was measured by using an inductively coupled plasma mass spectrometer (ICP-MS). The result shows that the total chlorine removal rate of the fly ash reaches 92.63 percent. Compared with the traditional water washing, the method has the advantages that the Zn content in the water washing waste liquid is reduced by 82.47 percent, the Pb content is reduced by 89.85 percent, the Cu content is reduced by 16.67 percent, the Cd content is reduced by 37.49 percent, and the concentration of the heavy metals in the water washing waste liquid does not exceed the comprehensive wastewater discharge standard (GB 8978-1996).
Example 4
Drying 10g of fly ash samples in a batch of fly ash, taking 5g of fly ash samples, and analyzing the compound components by using an X-ray fluorescence spectrometer to obtain CaO and Fe 2 O 3 、Al 2 O 3 、Na 2 O、K 2 O、MgO、P 2 O 5 、SO 3 Mass fraction data (27.25%, 3.1%, 13.04%, 5.84%, 5.37%, 3.16%, 1.33%, 6.49%, respectively) were imported into the data importing program, and the system automatically performed the entire water washing flow. Wherein, the liquid-solid ratio of the washing liquid to the fly ash is 3:1L/kg, the washing time is 30 minutes, the washing stirring frequency is 500r/min, and after the washing time exceeds 21 minutes, a real-time monitoring and pH value adjusting system is started to control the pH value to be in the range of 7+/-1.
After the washing, 10mL of untreated washing waste liquid was taken, and the total chlorine content was measured by using a Dynamics-1000 ion chromatograph, and the heavy metal content was measured by using an inductively coupled plasma mass spectrometer (ICP-MS). The result shows that the total chlorine removal rate of the fly ash reaches 91.78 percent. Compared with the traditional water washing method, the method has the advantages that the Zn content in the water washing waste liquid is reduced by 83.05%, the Pb content is reduced by 88.57%, the Cu content is reduced by 17.35%, the Cd content is reduced by 37.94%, and the concentration of the heavy metals in the water washing waste liquid does not exceed the comprehensive wastewater discharge standard (GB 8978-1996).
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method for enhancing the water-wash-out and dechlorination effects of fly ash and reducing the leaching toxicity of heavy metals, comprising the steps of:
detecting the composition of the fly ash substances and calculating the neutralization capacity of fly ash acid;
calculating the phosphoric acid addition amount of the water washing liquid according to the neutralization capacity of the fly ash acid and preparing phosphoric acid water washing liquid;
the method comprises the steps of (1) washing fly ash by using phosphoric acid washing liquid, monitoring the pH value in the washing process, and adjusting the pH value range of a water washing system end point to 7+/-1;
after the water washing is finished, carrying out solid-liquid separation on the slurry mixture obtained by the water washing, and respectively collecting fly ash and water washing waste liquid;
adding an organic precipitant or an inorganic reagent into the washing waste liquid, precipitating and separating heavy metals in the washing liquid, and collecting the detoxified washing waste liquid;
and (3) evaporating the detoxified water washing waste liquid with high efficiency, and recovering chlorine salt and water to obtain the water-washing waste liquid.
2. The method for enhancing the water-stripping chlorination effect of fly ash and reducing the leaching toxicity of heavy metals according to claim 1, wherein the detection uses X-ray fluorescence spectroscopy.
3. The method for enhancing the water-stripping chlorination effect of fly ash and reducing the leaching toxicity of heavy metals according to claim 1, wherein the mass of phosphoric acid required to be added per kilogram of fly ash is carried out by adopting the following formula:
wherein m is the mass kg of phosphoric acid required to be consumed per kilogram of fly ash;
is Al in fly ash 2 O 3 Mass fraction of (a);
is Fe in fly ash 2 O 3 Mass fraction of (a); omega CaO The mass fraction of CaO in the fly ash; omega MgO The mass fraction of MgO in the fly ash is as follows; />
Is K in fly ash 2 Mass fraction of O; />
Is Na in fly ash 2 Mass fraction of O; />
Is SO in fly ash 3 Mass fraction of (a); />
Is P in fly ash 2 O 5 Mass fraction of (c) is defined.
4. The method for enhancing the water-washing and dechlorination effects of fly ash and reducing the leaching toxicity of heavy metals according to claim 1, wherein the automatic calculation of the addition amount of phosphoric acid and the addition of phosphoric acid to the water washing liquid are realized by a programmable logic controller PLC.
5. The method for enhancing the water-stripping chlorination effect of fly ash and reducing the leaching toxicity of heavy metals according to claim 1, wherein the system for monitoring and adjusting the pH in real time is started when the water-washing time passes by 70%.
6. The method for enhancing the water-washing and dechlorination effects of fly ash and reducing the leaching toxicity of heavy metals according to claim 1, wherein the organic precipitant is at least one of TMT-102, MT-103 and RS-2568.
7. The method for enhancing the water-washing and dechlorination effects of fly ash and reducing the leaching toxicity of heavy metals according to claim 1, wherein the inorganic agent is Na 2 S、Na 2 CO 3 、FeSO 4 、Ca 3 (PO 4 ) 2 At least one of them.
8. The method for enhancing the water-washing and dechlorination effects of fly ash and reducing the leaching toxicity of heavy metals as claimed in claim 1, wherein the recovered water is used for water-washing the fly ash or is discharged up to the standard.
9. A system for enhancing the water-wash-out and dechlorination effects of fly ash and reducing the leaching toxicity of heavy metals, comprising: the device comprises a fly ash component detection device, a data processing device, a pickling solution preparation device, a water washing device, a dynamic detection and adjustment pH device, a solid-liquid separation device, a detoxification device and a high-efficiency evaporator;
the pickling solution preparation device is sequentially connected with the water washing device, the solid-liquid separation device, the detoxification device and the high-efficiency evaporator;
the washing device is also connected with a dynamic detection and pH adjustment device;
the data processing apparatus includes: a module for calculating the neutralization capacity of fly ash acid and a module for calculating the acid addition amount; the data processing device is respectively connected with the fly ash component detection device and the pickling solution preparation device,
the module for calculating the neutralization capacity of the fly ash acid, the module for calculating the acid adding amount and the pickling solution configuration device are automatically controlled by a PLC.
10. The use of phosphoric acid solution in washing out partially insoluble chloride salts in fly ash.
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| CN115138668A (en) * | 2022-06-29 | 2022-10-04 | 中国矿业大学(北京) | Fly ash treatment method |
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