CN115448349A - Method for recovering calcium salt from waste incineration fly ash - Google Patents
Method for recovering calcium salt from waste incineration fly ash Download PDFInfo
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- CN115448349A CN115448349A CN202211056041.3A CN202211056041A CN115448349A CN 115448349 A CN115448349 A CN 115448349A CN 202211056041 A CN202211056041 A CN 202211056041A CN 115448349 A CN115448349 A CN 115448349A
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- fly ash
- filtrate
- waste incineration
- calcium salt
- filter residue
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- 239000010881 fly ash Substances 0.000 title claims abstract description 75
- 238000004056 waste incineration Methods 0.000 title claims abstract description 61
- 159000000007 calcium salts Chemical class 0.000 title claims abstract description 51
- 238000000034 method Methods 0.000 title claims abstract description 50
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 112
- 238000006243 chemical reaction Methods 0.000 claims abstract description 90
- 239000000706 filtrate Substances 0.000 claims abstract description 54
- 235000011089 carbon dioxide Nutrition 0.000 claims abstract description 48
- 239000007788 liquid Substances 0.000 claims abstract description 47
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims abstract description 44
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 30
- 238000000926 separation method Methods 0.000 claims abstract description 29
- 229910000019 calcium carbonate Inorganic materials 0.000 claims abstract description 22
- 239000011259 mixed solution Substances 0.000 claims abstract description 18
- 238000003756 stirring Methods 0.000 claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims abstract description 13
- 238000005406 washing Methods 0.000 claims abstract description 9
- 238000004064 recycling Methods 0.000 claims description 15
- 230000008859 change Effects 0.000 claims description 6
- 239000012267 brine Substances 0.000 claims description 5
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims description 5
- 159000000000 sodium salts Chemical class 0.000 claims description 3
- 238000002425 crystallisation Methods 0.000 claims description 2
- 230000008025 crystallization Effects 0.000 claims description 2
- 238000001704 evaporation Methods 0.000 claims description 2
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 claims description 2
- 230000008020 evaporation Effects 0.000 claims 1
- 239000002699 waste material Substances 0.000 claims 1
- 239000001569 carbon dioxide Substances 0.000 abstract description 32
- 229910002092 carbon dioxide Inorganic materials 0.000 abstract description 32
- 238000011084 recovery Methods 0.000 abstract description 9
- 238000000859 sublimation Methods 0.000 description 15
- 230000008022 sublimation Effects 0.000 description 15
- 239000011575 calcium Substances 0.000 description 10
- 230000008569 process Effects 0.000 description 10
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 8
- 229910052791 calcium Inorganic materials 0.000 description 8
- 150000003839 salts Chemical class 0.000 description 7
- 229910000831 Steel Inorganic materials 0.000 description 6
- 238000009776 industrial production Methods 0.000 description 6
- 239000010959 steel Substances 0.000 description 6
- NKWPZUCBCARRDP-UHFFFAOYSA-L calcium bicarbonate Chemical group [Ca+2].OC([O-])=O.OC([O-])=O NKWPZUCBCARRDP-UHFFFAOYSA-L 0.000 description 5
- 229910000020 calcium bicarbonate Inorganic materials 0.000 description 5
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 5
- 239000000920 calcium hydroxide Substances 0.000 description 5
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 4
- 230000036632 reaction speed Effects 0.000 description 4
- 239000000292 calcium oxide Substances 0.000 description 3
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 238000005265 energy consumption Methods 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
- 239000002245 particle Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 229910003439 heavy metal oxide Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 159000000001 potassium salts Chemical class 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/18—Carbonates
- C01F11/181—Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by control of the carbonation conditions
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention provides a method for recovering calcium salt from waste incineration fly ash, which relates to the technical field of waste incineration fly ash recovery and comprises the following steps: washing the waste incineration fly ash for 10-20min, and carrying out solid-liquid separation to obtain a first filtrate and a first filter residue; adding the first filter residue and water into a reaction kettle respectively, and stirring uniformly to obtain a mixed solution; adding dry ice into the mixed solution, stirring and reacting for 1.5-3.5h at a preset rotating speed and at a first preset temperature, and carrying out solid-liquid separation to obtain a second filtrate and a second filter residue; and heating the second filtrate to a second preset temperature, standing for 20-40min, and performing solid-liquid separation to obtain calcium carbonate and a third filtrate. The invention can solve the technical problems of slow reaction process due to the adoption of carbon dioxide for carbonation reaction in the prior art.
Description
Technical Field
The invention relates to the technical field of waste incineration fly ash recovery, in particular to a method for recovering calcium salt from waste incineration fly ash.
Background
Along with the continuous improvement of the quality of life of people, the generation amount of garbage is also continuously increased, most of domestic garbage is treated by incineration, a large amount of fly ash is generated in the garbage incineration process, and the fly ash is generally gray or dark gray, so that the fly ash particles are uniformly distributed, the particle size is less than 300 microns, and the main range is 54-74 microns. The main components of the waste incineration fly ash are CaO, mgO and SiO 2 、Fe 2 O 3 And Al 2 O 3 Equal heavy metal oxide composition belonging to SiO 2 -Al 2 O 3 Metal oxide system, and the annual output of fly ash is considerable, and the fly ash has great potential of resource utilization. At present, the resource recycling of the waste incineration fly ash is very important.
At present, the content of calcium in the waste incineration fly ash is about 30 percent, the calcium mainly exists in the forms of calcium oxide, calcium carbonate and calcium sulfate, the calcium recovery of the part has considerable yield, the carbon dioxide decalcification principle of the fly ash is similar to the mineral carbonation principle, the effective components in the raw materials are leached by utilizing media such as acid, alkali, molten salt and the like, and then the leached effective components and CO are utilized 2 The carbonate is generated by carbonation reaction. However, since the solubility of carbon dioxide is limited, the whole reaction process is slow, which is not favorable for industrial production, and increases the process time, thereby increasing the process cost.
Therefore, the existing method for recovering calcium salt from waste incineration fly ash generally has the technical problems of slow reaction process and carbonation reaction by adopting carbon dioxide.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a method for recovering calcium salt from waste incineration fly ash, and aims to solve the technical problems that in the prior art, carbon dioxide is adopted for carbonation reaction, and the reaction process is slow.
The invention provides a method for recovering calcium salt from waste incineration fly ash, which comprises the following steps:
washing the waste incineration fly ash for 10-20min, and carrying out solid-liquid separation to obtain a first filtrate and a first filter residue;
adding the first filter residue and water into a reaction kettle respectively, and stirring uniformly to obtain a mixed solution;
adding dry ice into the mixed solution, stirring and reacting for 1.5-3.5h at a preset rotation speed and a first preset temperature, and performing solid-liquid separation to obtain a second filtrate and a second filter residue;
and heating the second filtrate to a second preset temperature, standing for 20-40min, and performing solid-liquid separation to obtain calcium carbonate and a third filtrate.
Compared with the prior art, the invention has the beneficial effects that: the method for recycling the calcium salt from the waste incineration fly ash provided by the invention comprises the following steps of washing the waste incineration fly ash for 10-20min, carrying out solid-liquid separation to obtain a first filtrate and a first filter residue so as to dissolve soluble salts in the waste incineration fly ash, wherein the first filtrate contains a large amount of soluble salts and can be used for recycling the brine; adding the first filter residue and water into a reaction kettle respectively, and stirring uniformly to obtain a mixed solution, so that the uniformity of the reaction after the subsequent dry ice is added is facilitated, and the reaction rate is improved; adding dry ice into the mixed solution, stirring and reacting for 1.5-3.5h at a preset rotating speed and a first preset temperature, performing solid-liquid separation to obtain a second filtrate and a second filter residue, wherein the setting of the preset rotating speed can keep the uniformity and the sufficiency of the reaction, and improve the reaction speed, the dry ice replaces direct introduction of carbon dioxide gas, the sublimation of the dry ice can increase the pressure in the reaction kettle, so that the high-pressure reaction condition can be realized, the reaction speed and the process can be improved, the industrial production can be facilitated, the cost can be reduced, the operation is simpler and more convenient, the complicated operation of increasing the pressure by connecting a steel cylinder and accessories such as a high-pressure resistant steel pipe, a pressure reducing valve, a booster pump and the like connected with the reaction kettle when the carbon dioxide gas is directly introduced is avoided, and meanwhile, the low temperature of the dry ice can directly reduce the reaction temperature, increase the solubility of the carbon dioxide, and further accelerate the reaction process; heating the second filtrate to a second preset temperature, standing for 20-40min, performing solid-liquid separation to obtain calcium carbonate and third filtrate, and increasing the decomposition of calcium bicarbonate in the second filtrate to form calcium carbonate by setting the second preset temperature, so that the reaction process is accelerated, calcium salt in the waste incineration fly ash can be effectively extracted, the recycling of substances is realized, the operation is simple, the recycling and reduction are realized, the whole process is simple, the energy consumption is low, the cost is saved, and the technical problems that the carbonation reaction is performed by adopting carbon dioxide and the reaction process is slow are solved.
Further, the solid-to-liquid ratio of the waste incineration fly ash to water is 1g:4-6ml.
Further, the solid-to-liquid ratio of the first filter residue to water is 1g:10-40ml.
Further, the adding mass of the dry ice is 200-500g.
Further, the preset rotating speed is 300-500rmp/min, and the first preset temperature is 1-10 ℃.
Further, the second preset temperature is 70-90 ℃.
Further, after the steps of heating the second filtrate to a second preset temperature, standing for 20-40min, and performing solid-liquid separation to obtain calcium carbonate and a third filtrate, the method further comprises the following steps:
adding the third filtrate and the second filter residue into a reaction kettle respectively, stirring uniformly, adding the dry ice, stirring at the preset rotation speed and the first preset temperature for reaction for 1.5-3.5 hours, and performing solid-liquid separation to obtain a fourth filtrate and a fourth filter residue;
heating the fourth filtrate to the second preset temperature, standing for 20-40min, and performing solid-liquid separation to obtain calcium carbonate and a fifth filtrate;
repeating the steps for 1-5 times to fully recover calcium salt in the waste incineration fly ash.
Furthermore, a pressure sensor is connected to the reaction kettle and is used for detecting a change value of the pressure in the reaction kettle.
Further, when the pressure sensor detects that the pressure change interval in the reaction kettle is smaller than a pressure threshold value, the repeated reaction is stopped to recover the calcium salt in the waste incineration fly ash.
Further, the first filtrate is subjected to evaporative crystallization to recover potassium salt and sodium salt, so that the brine is recycled.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a process flow diagram of calcium salt recovery from fly ash from waste incineration according to the present invention.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings, in order to make the objects, features and advantages of the invention more comprehensible. Several embodiments of the invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. As used herein, the terms "vertical," "horizontal," "left," "right," "up," "down," and the like are used for descriptive purposes only and not for purposes of indicating or implying that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the invention.
In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "fixed," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Example one
Referring to fig. 1, the method for recovering calcium salt from fly ash from waste incineration according to the present invention includes steps S10 to S13:
step S10, washing the waste incineration fly ash for 10-20min, and carrying out solid-liquid separation to obtain a first filtrate and a first filter residue;
wherein the solid-to-liquid ratio of the waste incineration fly ash to water is controlled to be 1g:4-6ml, washing the waste incineration fly ash for 10-20min to dissolve soluble salts in the waste incineration fly ash, wherein the first filtrate contains a large amount of soluble salts which can be used for recycling brine, and after washing, the first filtrate contains a large amount of potassium salts and sodium salts which can be recycled by evaporating and crystallizing to realize recycling of resources and recycle useful substances in the waste incineration fly ash, thereby realizing recycling and being green and environment-friendly.
In addition, in the water washing process, calcium oxide in the waste incineration fly ash can react with water to generate calcium hydroxide, so that the subsequent dry ice carbonation reaction is facilitated.
Step S11, adding the first filter residue and water into a reaction kettle respectively, and stirring uniformly to obtain a mixed solution;
wherein a large amount of calcium hydroxide exists in the first filter residue, and the solid-to-liquid ratio of the first filter residue to water is 1g:10-40ml, the mass of the first filter residue is 20-50g, the volume of water is 800-1200ml, the first filter residue and the water are respectively added into a reaction kettle and are uniformly stirred to obtain a mixed solution, the uniformity of the reaction after the subsequent dry ice is added is facilitated, and the reaction rate is improved.
In addition, a pressure sensor is arranged on the reaction kettle and can detect the change value of the pressure in the reaction kettle.
Step S12, adding dry ice into the mixed solution, stirring and reacting for 1.5-3.5 hours at a preset rotating speed and at a first preset temperature, and carrying out solid-liquid separation to obtain a second filtrate and a second filter residue;
wherein, dry Ice (Dry Ice) is solid carbon dioxide, the carbon dioxide is liquefied into colorless liquid under the pressure of 6250.5498kPa and then is rapidly solidified at low temperature to obtain the calcium carbonate, the adding mass of the Dry Ice is 200-500g, the preset rotating speed is 300-500rmp/min, the first preset temperature is 1-10 ℃, a large amount of calcium hydroxide exists in the mixed solution, the calcium hydroxide can react with the carbon dioxide to grow calcium carbonate precipitate, and then the calcium hydroxide continuously reacts with the carbon dioxide to grow calcium bicarbonate. In addition, the setting of the preset rotating speed can keep the uniformity and the sufficiency of the reaction and improve the reaction rate.
The sublimation of the dry ice increases the air pressure in the reaction kettle, and can generate a pressure of 2-6MPa, and the low temperature of the dry ice can rapidly reduce the temperature of the mixed solution to 1-10 ℃, and the solubility data shows that the solubility of the carbon dioxide is in direct proportion to the pressure and in inverse proportion to the temperature. The more the dry ice is added, the more the generated pressure is, the solubility of the carbon dioxide gas in the mixed solution is increased, meanwhile, the temperature of the added dry ice solution is reduced, the low temperature can also promote the carbon dioxide to be dissolved in the mixed solution, the reaction is facilitated, the reaction rate and the conversion rate are improved, and the mixed solution and the carbon dioxide are subjected to the following reactions:
Ca(OH) 2 +CO 2 ＝CaCO 3 ↓+H 2 O
CaCO 3 +H 2 O+CO 2 ＝Ca(HCO 3 ) 2
it should be noted that the reaction time is controlled from 1.5h to 3.5h according to the pressure change in the reaction kettle, a large amount of carbon dioxide is consumed in the reaction process, when the pressure is reduced to be stable and unchanged, the basic reaction is ended, and the reaction time is kept from 1.5h to 3.5h according to the different amount of the added dry ice. And when the pressure is stabilized for 30min, opening the reaction kettle to perform solid-liquid separation to obtain a second filtrate and a second filter residue. The second filtrate is calcium bicarbonate solution, the dry ice can release gas carbon dioxide 600-800 times larger than the solid volume when subliming, therefore, reaction pressure can be achieved only by putting a small amount of dry ice, the operation is simple and convenient, the reaction process is rapid, direct introduction of gas carbon dioxide is avoided, the solubility of carbon dioxide is limited, the whole reaction process is slow, the industrial production is not facilitated, the process time is increased, the process cost is increased, or the carbon dioxide passes through a gas booster pump, an air compressor, a high-pressure resistant pipeline and the like to be connected to form a high-pressure environment, but the cost is increased and the operation is complex. On the other hand, the dry ice reaction can ensure that the temperature in the reaction kettle is lower than 10 ℃, which is beneficial to dissolving the reaction carbon dioxide, quickening the reaction rate and improving the conversion rate and efficiency of the reaction.
And S13, heating the second filtrate to a second preset temperature, standing for 20-40min, and performing solid-liquid separation to obtain calcium carbonate and a third filtrate.
Wherein the second filtrate is calcium bicarbonate solution which is easily decomposed into calcium carbonate precipitate under normal temperature and pressure. Heating the mixture to accelerate the decomposition of the mixture, keeping the mixture at the second preset temperature of 70-90 ℃, standing for 20-40min, decomposing to obtain calcium carbonate precipitate, and performing solid-liquid separation to obtain calcium carbonate and third filtrate. In addition, after the steps of heating the second filtrate to a second preset temperature, standing for 20-40min, and performing solid-liquid separation to obtain calcium carbonate and a third filtrate, the method further comprises the following steps:
adding the third filtrate and the second filter residue into a reaction kettle respectively, stirring uniformly, adding the dry ice, stirring at the preset rotation speed and the first preset temperature for reaction for 1.5-3.5 hours, and performing solid-liquid separation to obtain a fourth filtrate and a fourth filter residue;
heating the fourth filtrate to the second preset temperature, standing for 20-40min, and performing solid-liquid separation to obtain calcium carbonate and a fifth filtrate;
repeating the steps for 1-5 times to fully recover calcium salt in the waste incineration fly ash.
And (3) fully recovering the calcium salt in the waste incineration fly ash through repeated carbonation reaction, and stopping the repeated carbonation reaction when a pressure sensor of the reaction kettle detects that the pressure change interval in the reaction kettle is smaller than a pressure threshold value, namely the calcium salt in the waste incineration fly ash basically completely reacts without continuing the carbonation reaction, wherein the purity of the calcium carbonate reaches 95 percent and the calcium carbonate can be used for industrial production.
In this embodiment, the solid-to-liquid ratio of the first filter residue to water is 1g:40ml, and the maximum sublimation pressure of dry ice is 6MPa.
Compared with the prior art, the method for recovering calcium salt from fly ash generated by burning garbage has the advantages that: the method for recycling the calcium salt from the waste incineration fly ash provided by the invention comprises the following steps of washing the waste incineration fly ash for 10-20min, carrying out solid-liquid separation to obtain a first filtrate and a first filter residue so as to dissolve soluble salts in the waste incineration fly ash, wherein the first filtrate contains a large amount of soluble salts and can be used for recycling the brine; adding the first filter residue and water into a reaction kettle respectively, and stirring uniformly to obtain a mixed solution, so that the uniformity of the reaction after the subsequent dry ice is added is facilitated, and the reaction rate is improved; adding dry ice into the mixed solution, stirring and reacting for 1.5-3.5h at a preset rotating speed and a first preset temperature, performing solid-liquid separation to obtain a second filtrate and a second filter residue, wherein the setting of the preset rotating speed can keep the uniformity and the sufficiency of the reaction, and improve the reaction speed, the dry ice replaces direct introduction of carbon dioxide gas, the sublimation of the dry ice can increase the pressure in the reaction kettle, so that the high-pressure reaction condition can be realized, the reaction speed and the process can be improved, the industrial production can be facilitated, the cost can be reduced, the operation is simpler and more convenient, the complicated operation of increasing the pressure by connecting a steel cylinder and accessories such as a high-pressure resistant steel pipe, a pressure reducing valve, a booster pump and the like connected with the reaction kettle when the carbon dioxide gas is directly introduced is avoided, and meanwhile, the low temperature of the dry ice can directly reduce the reaction temperature, increase the solubility of the carbon dioxide, and further accelerate the reaction process; heating the second filtrate to a second preset temperature, standing for 20-40min, performing solid-liquid separation to obtain calcium carbonate and third filtrate, and increasing the decomposition of calcium bicarbonate in the second filtrate to form calcium carbonate by setting the second preset temperature, so that the reaction process is accelerated, calcium salt in the waste incineration fly ash can be effectively extracted, the recycling of substances is realized, the operation is simple, the recycling and reduction are realized, the whole process is simple, the energy consumption is low, the cost is saved, and the technical problems that the carbonation reaction is performed by adopting carbon dioxide and the reaction process is slow are solved.
Example two
A second embodiment of the present invention provides a method for recovering calcium salt from waste incineration fly ash, which is different from the method for recovering calcium salt from waste incineration fly ash in the first embodiment in that:
the solid-liquid ratio of the first filter residue to water is 1g:30ml, and the maximum sublimation pressure of dry ice is 6MPa.
EXAMPLE III
A third embodiment of the present invention provides a method for recovering calcium salt from waste incineration fly ash, which is different from the method for recovering calcium salt from waste incineration fly ash in the first embodiment in that:
the solid-liquid ratio of the first filter residue to water is 1g:20ml, and the maximum sublimation pressure of dry ice is 6MPa.
Example four
A fourth embodiment of the present invention provides a method for recovering calcium salt from waste incineration fly ash, which is different from the method for recovering calcium salt from waste incineration fly ash in the first embodiment in that:
the solid-liquid ratio of the first filter residue to water is 1g:40ml, the maximum sublimation pressure of dry ice is 4.5MPa.
EXAMPLE five
A fifth embodiment of the present invention provides a method for recovering calcium salt from waste incineration fly ash, which is different from the method for recovering calcium salt from waste incineration fly ash in the first embodiment in that:
the solid-liquid ratio of the first filter residue to water is 1g:30ml, and the maximum sublimation pressure of dry ice is 4.5MPa.
EXAMPLE six
A sixth embodiment of the present invention provides a method for recovering calcium salt from waste incineration fly ash, which is different from the method for recovering calcium salt from waste incineration fly ash in the first embodiment in that:
the solid-liquid ratio of the first filter residue to water is 1g:20ml, and the maximum sublimation pressure of dry ice is 4.5MPa.
EXAMPLE seven
A seventh embodiment of the present invention provides a method for recovering calcium salt from waste incineration fly ash, which is different from the method for recovering calcium salt from waste incineration fly ash in the first embodiment in that:
the solid-liquid ratio of the first filter residue to water is 1g:40ml, the maximum sublimation pressure of dry ice is 3MPa.
Example eight
The eighth embodiment of the present invention provides a method for recovering calcium salt from waste incineration fly ash, which is different from the method for recovering calcium salt from waste incineration fly ash in the first embodiment in that:
the solid-liquid ratio of the first filter residue to water is 1g:30ml, and the maximum sublimation pressure of dry ice is 3MPa.
Example nine
A ninth embodiment of the present invention provides a method for recovering calcium salt from waste incineration fly ash, which is different from the method for recovering calcium salt from waste incineration fly ash in the first embodiment in that:
the solid-liquid ratio of the first filter residue to water is 1g:20ml, and the maximum sublimation pressure of dry ice is 3MPa.
Please refer to table 1 below, which shows parameters corresponding to the first to ninth embodiments of the present invention.
The recovery rate of calcium salt is calculated from the calcium content in the refuse incineration fly ash, and generally about 30% of calcium is contained, and the mass of the refuse incineration fly ash is assumed to be W, and therefore the mass of calcium in the refuse incineration fly ash is 0.3W, and the mass of calcium recovered by calculating the molar mass is assumed to be a, and the mass of calcium recovered is 40/100a, and therefore the recovery rate of calcium salt is 0.4 a/(0.3W).
It can be seen from the data of the first to third embodiments or the fourth to sixth embodiments or the seventh to ninth embodiments that when the maximum sublimation pressure of the dry ice is controlled to be constant, the solid-to-liquid ratio of the first residue to the water is gradually decreased, and the recovery rate of the calcium salt is gradually increased, so that the larger the volume of the water is, the higher the solubility of the dry ice is, so that the first residue and the carbon dioxide can be sufficiently reacted, and the more the volume of the water is, the more uniform the first residue is diffused, the higher the conversion rate of the carbonation reaction is, and the recovery rate of the calcium salt is increased.
Combining the data of the first filter residue and the water, the solid-liquid ratio of the first filter residue and the water is controlled to be constant, the recovery rate of the calcium salt is gradually increased and the reaction time is gradually reduced along with the continuous increase of the maximum sublimation pressure of the dry ice, and the sublimation of the dry ice can generate carbon dioxide gas which is 600-800 times larger than the self volume of the dry ice.
In conclusion, the direct introduction of carbon dioxide gas is replaced by the dry ice, so that high-pressure reaction conditions can be realized, the reaction rate and the conversion rate are improved, the industrial production is facilitated, the cost is reduced, the operation is simpler and more convenient, the complicated operation of increasing the pressure is realized through the connection of high-pressure resistant steel pipes, pressure reducing valves, booster pumps and other accessories, which are connected with a reaction kettle, of a steel cylinder when the carbon dioxide gas is directly introduced, and meanwhile, the reaction temperature is directly reduced due to the low temperature of the dry ice, the solubility of the carbon dioxide is increased, and the reaction process and the conversion rate are accelerated.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A method for recovering calcium salt from waste incineration fly ash, which is characterized by comprising the following steps:
washing the waste incineration fly ash for 10-20min, and carrying out solid-liquid separation to obtain a first filtrate and a first filter residue;
adding the first filter residue and water into a reaction kettle respectively, and stirring uniformly to obtain a mixed solution;
adding dry ice into the mixed solution, stirring and reacting for 1.5-3.5h at a preset rotating speed and at a first preset temperature, and carrying out solid-liquid separation to obtain a second filtrate and a second filter residue;
and heating the second filtrate to a second preset temperature, standing for 20-40min, and performing solid-liquid separation to obtain calcium carbonate and a third filtrate.
2. The method for recovering calcium salt from fly ash from refuse incineration of claim 1, wherein the solid-to-liquid ratio of the fly ash from refuse incineration to water is 1g:4-6ml.
3. The method for recovering calcium salt from waste incineration fly ash according to claim 1, wherein the solid-to-liquid ratio of the first filter residue to water is 1g:10-40ml, and the mass of the first filter residue is 20-50g.
4. The method for recovering calcium salt from fly ash from waste incineration of claim 1, wherein the mass of the dry ice added is 200 to 500g.
5. The method for recycling calcium salt from fly ash from waste incineration as claimed in claim 1, wherein the predetermined rotation speed is 300-500rmp/min, and the first predetermined temperature is 1-10 ℃.
6. The method for recycling calcium salt from fly ash from waste incineration of claim 1, wherein the second preset temperature is 70-90 ℃.
7. The method for recovering calcium salt from fly ash from waste incineration of claim 1, wherein after the steps of heating the second filtrate to a second preset temperature, standing for 20-40min, and performing solid-liquid separation to obtain calcium carbonate and a third filtrate, the method further comprises:
adding the third filtrate and the second filter residue into a reaction kettle respectively, stirring uniformly, adding the dry ice, stirring at the preset rotation speed and the first preset temperature for reaction for 1.5-3.5 hours, and performing solid-liquid separation to obtain a fourth filtrate and a fourth filter residue;
heating the fourth filtrate to the second preset temperature, standing for 20-40min, and performing solid-liquid separation to obtain calcium carbonate and a fifth filtrate;
repeating the steps for 1-5 times to fully recover calcium salt in the waste incineration fly ash.
8. The method for recycling calcium salt from fly ash generated in the incineration of waste according to claim 7, wherein a pressure sensor is installed in the reaction vessel, and the pressure sensor is used for detecting the change value of the pressure in the reaction vessel.
9. The method of claim 8, wherein when the pressure sensor detects that the pressure variation interval in the reaction kettle is smaller than the pressure threshold, the repeated reaction is stopped to recover the calcium salt in the fly ash.
10. The method for recovering calcium salt from waste incineration fly ash according to claim 1, wherein the first filtrate is used for recovering potassium salt and sodium salt by evaporation crystallization to realize brine resource.
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| CN116944221A (en) * | 2023-07-11 | 2023-10-27 | 北京金隅琉水环保科技有限公司 | Fly ash online decalcification method capable of reducing sodium carbonate consumption |
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