CN114477868A - Method for synchronously preparing waste incineration fly ash roadbed brick and polyaluminium chloride - Google Patents
Method for synchronously preparing waste incineration fly ash roadbed brick and polyaluminium chloride Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/006—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing mineral polymers, e.g. geopolymers of the Davidovits type
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- C01F7/48—Halides, with or without other cations besides aluminium
- C01F7/56—Chlorides
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- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00017—Aspects relating to the protection of the environment
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Abstract
The invention discloses a method for synchronously preparing waste incineration fly ash roadbed bricks and polyaluminium chloride, which belongs to the technical field of resource utilization of hazardous wastes. The highest compression strength of the high-strength brick prepared by the invention can reach 48.17MPa, and the content of the prepared polyaluminium chloride alumina can reach 51.75 percent.
Description
Technical Field
The invention relates to a method for synchronously preparing a waste incineration fly ash roadbed brick and polyaluminium chloride, belonging to the technical field of resource utilization of hazardous wastes.
Background
The garbage incineration is mainly realized by two incineration modes of a fluidized bed and a grate furnace. The grate furnace is more and more favored due to the characteristics of simple operation, high combustion efficiency, stable operation, high automation degree and the like, and the occupancy rate of the grate furnace in the waste incineration power plant in China is about 80 percent and is also increased year by year. Meanwhile, compared with fluidized bed incineration, the fly ash production of the grate furnace garbage incinerator is very low, which is about 2% -5% of the total amount of garbage.
However, the components in the fly ash burned by the grate furnace are obviously different from those of the fly ash burned by the fluidized bed, and besides high content of calcium, the content of chlorine in the fly ash burned by the grate furnace is 15-35%. The waste incineration fly ash also contains heavy metals and dioxin, and belongs to dangerous waste. In view of the high calcium property of the waste incineration fly ash, some researchers in the industry are focusing on developing a solidification stabilization treatment method for the waste incineration fly ash. The technologies can effectively control the environmental pollution caused by heavy metals and dioxin in the fly ash, but the removal and utilization of chloride ions in the fly ash are neglected, so that the disposed waste incineration fly ash can only be buried again and cannot be circulated to the market as building materials.
For removing chlorine in waste incineration fly ash, a water washing method is the mainstream method at present. Although the water washing method can effectively remove free chlorine in the fly ash, a large amount of water washing waste liquid generated in the disposal process needs secondary advanced treatment. Meanwhile, the water washing method can reduce the alkalinity and the calcium content of the fly ash, so that the subsequent solidification and stabilization treatment of the fly ash is not utilized.
Therefore, based on the above analysis, it is the key to solve the above problems if a method can be developed which can achieve effective solidification of fly ash and make full use of chlorine in fly ash without generating any secondary pollution waste.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a method for synchronously preparing waste incineration fly ash roadbed bricks and polyaluminium chloride.
In order to solve the technical problems, the invention is realized by adopting the following technical scheme:
the invention provides a method for synchronously preparing waste incineration fly ash roadbed bricks and polyaluminium chloride, which comprises the following steps:
respectively weighing water and waste incineration fly ash, mixing and stirring the water and the waste incineration fly ash into paste to obtain fly ash slurry, and filling the fly ash slurry into a sample area of an electrolytic cell;
adding aluminum hydroxide into the anode chamber of the electrolytic cell, and injecting water into the anode chamber until the water is flush with the fly ash slurry in the sample area;
dissolving sodium silicate in water to prepare a sodium silicate aqueous solution, and injecting the sodium silicate aqueous solution into a cathode chamber of an electrolytic cell until the sodium silicate aqueous solution is flush with fly ash slurry in a sample area;
connecting the anode and the cathode of the electrolytic cell with a direct current power supply, conducting acid immersion slurry out of the anode chamber after treating for 0.25-6 hours, and conducting electrically-driven silicon-loaded flying mortar out of the sample area;
filtering the acid leaching slurry to obtain a liquid part which is a chlorine-aluminum liquid and an obtained solid part which is acid leaching residue;
respectively weighing water and acid leaching residues, mixing, stirring and filtering to obtain a solid part which is water washing acid leaching residues;
mixing the washing acid leaching residue and the electrically-driven silicon-loaded fly ash slurry, uniformly stirring, molding and maintaining to obtain the high-strength brick;
and drying the aluminum chloride solution, and grinding the aluminum chloride solution into powder to obtain the polyaluminum chloride.
Preferably, the mass ratio of the aluminum hydroxide to the waste incineration fly ash is (7.5-60): 100.
preferably, the mass ratio of the aluminum hydroxide to the waste incineration fly ash is (15-45): 100.
preferably, the liquid-solid ratio of the water to the waste incineration fly ash which are respectively weighed is 0.25-0.45 mL/g.
Preferably, the solid content of the sodium silicate aqueous solution is 5-40%.
Preferably, the solid content of the sodium silicate aqueous solution is 10-40%.
Preferably, the anode and the cathode of the electrolytic cell are connected with a direct current power supply, after 0.5-4.5 hours of treatment, acid-soaked slurry is led out from the anode chamber, and electrically-driven silicon-loaded fly ash slurry is led out from the sample area.
Preferably, the voltage of the direct current power supply is 50-350V, and the current is 100-1000A.
Preferably, the liquid-solid ratio of the water to the acid leaching residue is 1-3 mL/g.
Preferably, the chlorine-aluminum liquid is dried at the temperature of 50-150 ℃.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a method for synchronously preparing a waste incineration fly ash roadbed brick and polyaluminium chloride, which has simple preparation process, can synchronously prepare a high-strength brick and a polyaluminium chloride flocculating agent by utilizing waste incineration fly ash and aluminium hydroxide and combining an electrolysis system, completely utilizes hydrogen ions and hydroxyl generated by the waste incineration fly ash, the aluminium hydroxide and electrode electrolysis water in the preparation process, does not generate other wastes, and can prepare the high-strength brick with the highest compression strength of 48.17MPa and the prepared polyaluminium chloride with the highest alumina content of 51.75 percent.
Drawings
FIG. 1 is a flow chart of a method for synchronously preparing waste incineration fly ash roadbed bricks and polyaluminium chloride according to an embodiment of the invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
The experimental methods used in the following examples are not specifically described, and the materials, reagents and the like used in the following examples are generally commercially available under the usual conditions without specific descriptions.
It should be noted that the fly ash from incineration of household garbage is collected by a bag-type dust collector from a power plant from incineration of household garbage. The waste incineration fly ash sample mainly contains 30-45% of CaO, 10-20% of Cl and 6-12% of Na2O、6％～12％K2O、3％～8％SO2、3％～8％SiO2、2％～6％MgO、2％～6％Fe2O3、2％～6％Al2O3、0.5％～1.5％CrO30.1 to 0.5 percent of CdO, 0.1 to 0.5 percent of NiO, 0.1 to 0.5 percent of PbO and the like.
The invention relates to a method for synchronously preparing waste incineration fly ash roadbed bricks and polyaluminium chloride, which comprises the following steps: respectively weighing water and waste incineration fly ash, mixing and stirring the water and the waste incineration fly ash into paste to obtain fly ash slurry, and filling the fly ash slurry into a sample area of an electrolytic cell. In some embodiments, the liquid-solid ratio of the water and the waste incineration fly ash which are respectively weighed is 0.25-0.45 mL/g, but not limited thereto;
the method is characterized in that an electrolytic cell is required to be used in the process of preparing the high-strength brick and the polyaluminium chloride, and specifically, the electrolytic cell consists of an anode chamber, a sample area and a cathode chamber, wherein an anion exchange membrane is arranged between the sample area and the anode chamber;
adding aluminum hydroxide into the anode chamber of the electrolytic cell, and injecting water into the anode chamber until the water is flush with the fly ash slurry in the sample area; in some embodiments, the mass ratio of the aluminum hydroxide to the waste incineration fly ash is (7.5-60): 100. preferably, the mass ratio of the aluminum hydroxide to the waste incineration fly ash is (15-45): 100.
sodium silicate is dissolved in water to prepare a sodium silicate aqueous solution, and the sodium silicate aqueous solution is injected into a cathode chamber of the electrolytic cell to be flush with fly ash slurry in a sample area. The solid content of the sodium silicate aqueous solution is 5 to 40 percent. In a preferred embodiment, the solid content of the sodium silicate solution is 10-40%.
Connecting the anode and the cathode of the electrolytic cell with a direct current power supply, conducting the direct current power supply for 0.25-6 hours, then conducting the acid-leaching slurry from the anode chamber, and conducting the electrically-driven silicon-carrying flying mortar from the sample area, wherein the treatment time is 0.5-4.5 hours as a preferred embodiment mode. In some embodiments, the maximum setting value of the DC power supply voltage is 50-350V, and the maximum setting value of the DC power supply current is 100-1000A.
And filtering the acid leaching slurry to obtain a liquid part which is a chlorine-aluminum liquid and an obtained solid part which is acid leaching residue. Respectively weighing water and acid leaching residues, mixing, stirring and filtering to obtain a solid part which is water washing acid leaching residues; the liquid-solid ratio of the water to the acid leaching residue may be 1 to 3mL/g, but is not limited thereto.
Mixing the washing acid leaching residue and the electrically-driven silicon-loaded fly ash slurry, uniformly stirring, molding and maintaining to obtain the high-strength brick;
meanwhile, drying the chlorine aluminum liquid at the temperature of 50-150 ℃, and grinding into powder to prepare the polyaluminium chloride.
The present invention will be described in detail below by way of examples, but the scope of the present invention is not limited thereto.
Example 1 quality ratio of aluminum hydroxide to fly ash from waste incineration influence of strength of high strength brick and polyaluminium chloride aluminum oxide mass fraction
Weighing aluminum hydroxide and waste incineration fly ash respectively according to the mass ratio of the aluminum hydroxide to the waste incineration fly ash of 7.5:100, 10:100, 12.5:100, 15:100, 30:100, 45:100, 50:100, 55:100 and 60: 100.
According to the liquid-solid ratio of water to the waste incineration fly ash of 0.25mL/g, water and the waste incineration fly ash are respectively weighed, mixed, stirred into paste and filled in a sample area. Sodium silicate is dissolved in water to prepare a sodium silicate aqueous solution, wherein the solid content of the sodium silicate is 10%.
Aluminum hydroxide was added to the anode compartment and water was injected into the anode compartment to level with the sample area fly ash slurry. The aqueous sodium silicate solution was then injected into the cathode chamber to level with the sample area fly ash slurry. Connecting the anode and the cathode of the electrolytic cell, connecting a direct current power supply, treating for 0.5 hour, leading out mixed slurry from the anode chamber to be acid leaching slurry, and leading out fly ash slurry from the sample area to be electric-driven silicon-loaded fly ash slurry, wherein the maximum set value of the power supply voltage is 50V, and the maximum set value of the power supply current is 100A.
And filtering the acid leaching slurry to obtain a liquid part which is a chlorine-aluminum liquid and an obtained solid part which is acid leaching residue. Respectively weighing water and acid leaching residue according to the solid-to-liquid ratio of 1mL/g of water to the acid leaching residue, mixing, stirring and filtering to obtain a solid part which is water washing acid leaching residue. And mixing the washing acid leaching residue and the electrically-driven silicon-carried fly ash slurry, uniformly stirring, putting into a mold, and maintaining to obtain the high-strength brick. Drying the chlorine aluminum liquid at the temperature of 50 ℃, and grinding into powder to obtain the polyaluminium chloride.
And (3) testing the compressive strength: the compression strength test of the high-strength brick prepared by the invention is carried out according to the standard of concrete solid brick (GB T21144).
And (3) measuring the mass fraction of the polyaluminium chloride alumina: the mass fraction of the polyaluminium chloride alumina prepared by the invention is measured according to water treatment agent polyaluminium chloride (GB/T22627).
In this example, the mass ratio of the aluminum hydroxide to the fly ash from waste incineration is shown in table 1 for the determination results of the strength of the prepared high strength brick and the mass fraction of polyaluminium chloride.
TABLE 1 determination results of the mass ratio of aluminum hydroxide to fly ash from incineration of refuse on the basis of the strength of the high strength brick and the mass fraction of polyaluminum oxychloride alumina
As can be seen from Table 1, the polyaluminium chloride alumina mass fraction did not change significantly as the mass ratio of aluminium hydroxide to refuse incineration fly ash was changed. And when the mass ratio of the aluminum hydroxide to the waste incineration fly ash is less than 15:100 (as shown in table 1, when the mass ratio of the aluminum hydroxide to the waste incineration fly ash is 12.5:100, 10:100, 7.5:100 and lower ratios not listed in table 1), the amount of water-washed acid leaching residues later incorporated into the electric silica-loaded mortar is reduced, so that the formation of hydrated calcium aluminate and calcium aluminosilicate geopolymers is reduced, resulting in a significant reduction in high strength brick strength as the mass ratio of the aluminum hydroxide to the waste incineration fly ash is reduced. When the mass ratio of the aluminum hydroxide to the waste incineration fly ash is 15-45: 100 (as shown in table 1, the mass ratio of the aluminum hydroxide to the waste incineration fly ash is 15:100, 30:100, 45: 100), under the action of electromigration, chloride ions in the fly ash in the sample area pass through the anion exchange membrane to reach the anode chamber. The chloride ions combine with the hydrogen ions to generate hydrogen chloride, and the hydrogen chloride reacts with the aluminum hydroxide to generate aluminum trichloride and water. The water washing acid leaching residue is mixed with the electrically-driven silicon-carried fly ash slurry, and aluminum in the water washing acid leaching residue can react with calcium hydroxide and calcium silicate to generate hydrated calcium aluminate and calcium aluminosilicate geopolymer. Finally, the strength of the high-strength brick is higher than 36 MPa. When the mass ratio of the aluminum hydroxide to the waste incineration fly ash is more than 45:100 (as shown in table 1, when the mass ratio of the aluminum hydroxide to the waste incineration fly ash is 50:100, 10:100, 7.5:100 and higher ratios not listed in table 1), the aluminum hydroxide is excessive, the acid leaching residue of water washing which is later put into the electric silicon-driven fly ash is excessive, and the silicon-aluminum content is unbalanced in the curing reaction process, so that the strength of the high-strength brick is gradually reduced along with the further increase of the mass ratio of the aluminum hydroxide to the waste incineration fly ash.
Therefore, in summary, the benefit and the cost are combined, and when the mass ratio of the aluminum hydroxide to the waste incineration fly ash is 15-45: 100, the strength of the prepared high-strength brick and the mass fraction of the polyaluminium chloride alumina are improved most beneficially.
Example 2 the Effect of the solids content of aqueous sodium silicate solution on the Strength of the resulting high Strength brick and the polyaluminum aluminum oxide chloride Mass fraction
Weighing aluminum hydroxide and waste incineration fly ash respectively according to the mass ratio of the aluminum hydroxide to the waste incineration fly ash of 45: 100. According to the liquid-solid ratio of water to the waste incineration fly ash of 0.35mL/g, water and the waste incineration fly ash are respectively weighed, mixed, stirred into paste and filled in a sample area.
Dissolving sodium silicate in water to prepare a sodium silicate aqueous solution, wherein the solid contents of the sodium silicate solution are respectively 5%, 7%, 9%, 10%, 20%, 30% and 40%. Aluminum hydroxide was added to the anode compartment and water was injected into the anode compartment to level with the sample area fly ash slurry. The aqueous sodium silicate solution was injected into the cathode chamber to level with the fly ash slurry in the sample area. Connecting the anode and the cathode of the electrolytic cell, connecting the power supply to a direct current power supply, after 2.5 hours of treatment, leading out mixed slurry from the anode chamber to be acid leaching slurry, and leading out fly ash slurry from the sample area to be electric-driven silicon-loaded fly ash slurry, wherein the maximum set value of the power supply voltage is 200V, and the maximum set value of the power supply current is 550A.
And filtering the acid leaching slurry to obtain a liquid part which is a chlorine-aluminum liquid and an obtained solid part which is acid leaching residue. Respectively weighing water and acid leaching residues according to the solid-to-liquid ratio of 2mL/g of water to the acid leaching residues, mixing, stirring and filtering to obtain a solid part which is water washing acid leaching residues. And mixing the washing acid leaching residue and the electrically-driven silicon-carried fly ash slurry, uniformly stirring, putting into a mold, and maintaining to obtain the high-strength brick. Drying the chlorine aluminum liquid at the temperature of 100 ℃, and grinding into powder to obtain the polyaluminium chloride.
The compression strength test and the polyaluminium chloride alumina mass fraction measurement are the same as those of example 1. Wherein, the solid content of sodium silicate is the determination result of the strength and the mass fraction of the polyaluminium chloride alumina of the prepared high-strength brick, please refer to table 2.
TABLE 2 determination of solid content of sodium silicate aqueous solution on strength of the prepared high strength brick and polyaluminium chloride alumina mass fraction
As can be seen from Table 2, as the solid content of sodium silicate increases, the number of mobile ions in the electrolytic cell increases, the hydrolysis efficiency increases, and the mass fraction of polyaluminum aluminum oxide gradually increases. As the sodium silicate solids content increases, the cathode compartment silicate and hydroxide are transferred to the sample area to react with calcium in the fly ash slurry in the sample area to form calcium silicate hydrate under electromigration, and the hydroxide can combine with calcium ions to form calcium hydroxide. And when the solid content of the sodium silicate solution is 10-40% (as shown in table 2, when the solid content of the sodium silicate is 10%, 20%, 30% and 40%), the strength of the high-strength brick is higher than 40 MPa.
In summary, the benefit and the cost are combined, and when the solid content of the sodium silicate is equal to 10-40%, the strength of the prepared high-strength brick and the mass fraction of the polyaluminium chloride alumina are improved.
Example 3 Effect of electrokinetic handling time on Strength of high Strength brick produced and polyaluminum oxychloride aluminum oxide Mass fraction
Weighing aluminum hydroxide and waste incineration fly ash respectively according to the mass ratio of the aluminum hydroxide to the waste incineration fly ash of 45: 100. Respectively weighing water and waste incineration fly ash according to the liquid-solid ratio of 0.45mL/g of water to waste incineration fly ash, mixing, stirring into paste, and filling in a sample area. Sodium silicate is dissolved in water to prepare a sodium silicate aqueous solution, wherein the solid content of the sodium silicate is 40%. Aluminum hydroxide was added to the anode compartment and water was injected into the anode compartment to level with the sample area fly ash slurry.
The aqueous sodium silicate solution was injected into the cathode chamber to level with the fly ash slurry in the sample area. And (3) switching on the anode and the cathode of the electrolytic cell, switching on the power supply to be a direct current power supply, treating for 0.25 hour, 0.35 hour, 0.45 hour, 0.5 hour, 2.5 hour, 4.5 hour, 5 hour, 5.5 hour and 6 hour respectively, then leading out mixed slurry from the anode chamber to be acid leaching slurry, and leading out fly ash slurry from the sample area to be electric-driven silicon-loaded fly ash slurry, wherein the maximum set value of the power supply voltage is 350V, and the maximum set value of the power supply current is 1000A. And filtering the acid leaching slurry to obtain a liquid part which is a chlorine-aluminum liquid and an obtained solid part which is acid leaching residue. Respectively weighing water and acid leaching residue according to the liquid-solid ratio of 3:1 of water to acid leaching residue, mixing, stirring and filtering to obtain a solid part which is water washing acid leaching residue. And mixing the washing acid leaching residue and the electrically-driven silicon-carried fly ash slurry, uniformly stirring, putting into a mold, and maintaining to obtain the high-strength brick. Drying the chlorine aluminum liquid at the temperature of 150 ℃, and grinding into powder to obtain the polyaluminium chloride.
The compression strength test and the polyaluminium chloride alumina mass fraction measurement are the same as those of example 1. The measurement results of the electric treatment time on the strength of the prepared high-strength brick and the mass fraction of the polyaluminium chloride alumina are shown in Table 3.
TABLE 3 determination of the strength of the resulting high-strength bricks and the mass fraction of polyaluminium chloride oxide by the duration of the electrokinetic treatment
As can be seen from table 3, when the electrokinetic treatment time is less than 0.5 hours (as in table 3, electrokinetic treatment times are 0.45 hours, 0.35 hours, 0.25 hours, and lower values not listed in table 3), the electrolytic hydrolysis time is insufficient, less hydrogen ions and hydroxide radicals are generated, and the ionic electromigration efficiency is low, resulting in a significant decrease in both high brick strength and polyaluminum aluminum oxide mass fraction with decreasing electrokinetic treatment time. When the electrokinetic treatment time is equal to 0.5-4.5 hours (as shown in table 3, the electrokinetic treatment time is 0.5 hours, 2.5 hours, 4.5 hours and higher values not listed in table 3), after the power is turned on, the water on the surface of the anode is hydrolyzed to generate hydrogen ions and oxygen, and the water on the surface of the cathode is hydrolyzed to generate hydroxyl and hydrogen. Under electromigration, chloride ions in the sample area fly ash slurry pass through the anion exchange membrane to the anode chamber. The chloride ions combine with the hydrogen ions to generate hydrogen chloride, and the hydrogen chloride reacts with the aluminum hydroxide to generate aluminum trichloride and water. The anion exchange membrane is effective to inhibit migration of aluminum ions to the sample area. Meanwhile, under the action of electromigration, silicate and hydroxide in the cathode chamber are transferred to the sample area to react with calcium in fly ash in the sample area to generate calcium silicate hydrate, and the hydroxide can be combined with calcium ions to generate calcium hydroxide. The water washing acid leaching residue is mixed with the electrically-driven silicon-carried fly ash slurry, and aluminum in the water washing acid leaching residue can react with calcium hydroxide and calcium silicate to generate hydrated calcium aluminate and calcium aluminosilicate geopolymer. And drying the aluminum chloride solution, wherein aluminum chloride is subjected to hydrolytic polymerization in the drying process to generate polyaluminum chloride. Finally, the strength of the high-strength brick is higher than 43MPa, and the mass fraction of the polyaluminium chloride alumina is higher than 44%. When the electrokinetic treatment time is greater than 4.5 hours (as in table 3, the electrokinetic treatment time is 5 hours, 5.5 hours, 6 hours, and higher values not listed in table 3), the electrokinetic time is too long, hydroxide and silicate migrate further from the sample area to the anode compartment, and a portion of the calcium ions migrate to the cathode compartment to precipitate, resulting in a significant decrease in both high brick strength and polyaluminum chloride alumina mass fraction with further increase in electrokinetic treatment time.
Therefore, in summary, the benefit and cost are combined, and when the electric treatment time is equal to 0.5-4.5 hours, the strength of the prepared high-strength brick and the mass fraction of the polyaluminium chloride alumina are improved most beneficially.
The different comparison treatment processes of the comparative example have the influence on the strength of the prepared high-strength brick and the mass fraction of the polyaluminium chloride alumina
The process of the invention comprises the following steps: weighing aluminum hydroxide and waste incineration fly ash respectively according to the mass ratio of the aluminum hydroxide to the waste incineration fly ash of 45: 100. Respectively weighing water and the waste incineration fly ash according to the liquid-solid ratio of the water to the waste incineration fly ash of 0.45mL/g, mixing, stirring into paste, and filling in a sample area. Sodium silicate is dissolved in water to prepare a sodium silicate aqueous solution, wherein the solid content of the sodium silicate is 40%. Aluminum hydroxide was added to the anode compartment and water was injected into the anode compartment to level with the sample area fly ash slurry. The aqueous sodium silicate solution was then injected into the cathode chamber to level with the sample area fly ash slurry.
The anode and cathode of the electrolytic cell were switched on, and after 4.5 hours of treatment, the mixed slurry derived from the anode compartment was an acid-leached slurry, and the fly ash slurry derived from the sample zone was an electrically driven silicon-loaded fly ash slurry, with a maximum set value of power supply voltage of 350V and a maximum set value of power supply current of 1000A. And filtering the acid leaching slurry to obtain a liquid part which is a chlorine-aluminum liquid and an obtained solid part which is acid leaching residue. Respectively weighing water and acid leaching residues according to the solid-to-liquid ratio of 3mL/g of water to the acid leaching residues, mixing, stirring and filtering to obtain a solid part which is water washing acid leaching residues. And mixing the washing acid leaching residue and the electrically-driven silicon-carried fly ash slurry, uniformly stirring, molding and maintaining to obtain the high-strength brick. Drying the chlorine aluminum liquid at the temperature of 150 ℃, and grinding into powder to obtain the polyaluminium chloride.
Comparative treatment process 1: weighing aluminum hydroxide and waste incineration fly ash respectively according to the mass ratio of the aluminum hydroxide to the waste incineration fly ash of 45: 100. Respectively weighing water and waste incineration fly ash according to the liquid-solid ratio of 0.45mL/g of water to waste incineration fly ash, mixing, stirring into paste, and filling in a sample area. And dissolving sodium silicate in water to prepare a sodium silicate aqueous solution, wherein the solid content of the sodium silicate is 40%. Aluminum hydroxide was added to the anode compartment and water was injected into the anode compartment to level with the sample area fly ash slurry. The cathode compartment was then filled with an aqueous sodium silicate solution to level with the fly ash slurry in the sample area.
After 4.5 hours, the mixed slurry was an aluminum slurry which was withdrawn from the anode chamber, and the fly ash slurry which was withdrawn from the sample area was a silica-loaded fly ash slurry. And filtering the aluminum slurry to obtain a liquid part which is aluminum liquid and an obtained solid part which is aluminum slag. Respectively weighing water and aluminum slag according to the liquid-solid ratio of 3mL/g of water to aluminum slag, mixing, stirring and filtering to obtain a solid part, namely water-washed aluminum slag. And mixing the washed aluminum slag and the silicon-loaded fly ash slurry, uniformly stirring, putting into a mold, and maintaining to obtain the high-strength brick. Drying the chlorine aluminum liquid at the temperature of 150 ℃, and grinding into powder to obtain the polyaluminium chloride.
Comparative treatment process 2: weighing aluminum hydroxide and waste incineration fly ash respectively according to the mass ratio of the aluminum hydroxide to the waste incineration fly ash of 45: 100. Respectively weighing water and waste incineration fly ash according to the liquid-solid ratio of 0.45mL/g of water to waste incineration fly ash, mixing, stirring into paste, and filling in a sample area. Aluminum hydroxide was added to the anode compartment and water was injected into the anode compartment to level with the sample area fly ash slurry. Water was then injected into the cathode chamber to level with the sample area fly ash slurry.
Connecting the anode and the cathode of the electrolytic cell, connecting the power supply to a direct current power supply, treating for 4.5 hours, leading out mixed slurry from the anode chamber to be acid leaching slurry, and leading out fly ash slurry from the sample area to be electric drive fly ash slurry, wherein the maximum set value of the power supply voltage is 350V, and the maximum set value of the power supply current is 1000A. And filtering the acid leaching slurry to obtain a liquid part which is a chlorine-aluminum liquid and an obtained solid part which is acid leaching residue. Respectively weighing water and acid leaching residue according to the liquid-solid ratio of 3:1 of water to acid leaching residue, mixing, stirring and filtering to obtain a solid part which is water washing acid leaching residue. And mixing the washing acid leaching residue and the electrically-driven fly ash slurry, uniformly stirring, molding, and maintaining to obtain the high-strength brick. Drying the chlorine aluminum liquid at the temperature of 150 ℃, and grinding into powder to obtain the polyaluminium chloride.
The compression strength test and the polyaluminium chloride alumina mass fraction determination are the same as those in example 1, wherein the determination results of the strength of the prepared high-strength brick and the polyaluminium chloride alumina mass fraction by different comparative treatment processes are shown in table 4.
TABLE 4 determination results of different comparative treatment processes on the strength of the prepared high-strength brick and the mass fraction of polyaluminium chloride alumina
As can be seen from Table 4, the strength of the high-strength brick prepared by the process and the mass fraction of the aluminum polychloride are both obviously higher than those of the comparative treatment process 1 and the comparative treatment process 2 and higher than the sum of the treatment process 1 and the comparative treatment process 2.
For the process, after the power is switched on, the water on the surface of the anode is hydrolyzed to generate hydrogen ions and oxygen, and the water on the surface of the cathode is hydrolyzed to generate hydroxyl and hydrogen. Under electromigration, chloride ions in the sample area fly ash slurry pass through the anion exchange membrane to the anode chamber. The chloride ions combine with the hydrogen ions to generate hydrogen chloride, and the hydrogen chloride reacts with the aluminum hydroxide to generate aluminum trichloride and water. The anion exchange membrane is effective to inhibit migration of aluminum ions to the sample area. Meanwhile, under the action of electromigration, silicate and hydroxide in the cathode chamber are transferred to the sample area to react with calcium in fly ash in the sample area to generate calcium silicate hydrate, and the hydroxide can be combined with calcium ions to generate calcium hydroxide. The acid leaching residue is mixed with water, and chloride ions adsorbed on the surface of the acid leaching residue can be removed in the stirring process. The water washing acid leaching residue is mixed with the electrically-driven silicon-carried fly ash slurry, and aluminum in the water washing acid leaching residue can react with calcium hydroxide and calcium silicate to generate hydrated calcium aluminate and calcium aluminosilicate geopolymer. And drying the aluminum chloride solution, wherein aluminum chloride is subjected to hydrolytic polymerization in the drying process to generate polyaluminum chloride.
In contrast to the process 1, the power supply is not turned on, the electrode surface hydrolysis and electromigration phenomena cannot occur, only a small amount of aluminum hydroxide is dissolved, and after the water-washed aluminum slag and the silicon-loaded fly ash slurry are mixed, the reaction between the calcium silicate hydrate and the geopolymer is weak due to insufficient alkali excitation, so that the strength of the high-strength brick and the mass fraction of the polyaluminium chloride alumina are obviously lower than those of the process of the invention.
For comparative process 2, water was added to the cathode compartment instead of sodium silicate solution during the electrokinetic process, which decreased the overall electrolysis system conductivity and current, thereby affecting the electrode surface hydrolysis efficiency and electromigration efficiency. Meanwhile, after the washing acid leaching residue and the electric-driving fly ash slurry are mixed, due to the lack of silicate, the reaction of hydrated calcium silicate is lost, so that the strength of the high-strength brick and the mass fraction of the polyaluminium chloride alumina are obviously lower than those of the process.
After studying the essence of the present invention, it will be understood by those skilled in the art that the reaction mechanism of the present invention is:
after the anode and the cathode are connected, the water on the surface of the anode is hydrolyzed to generate hydrogen ions and oxygen, and the water on the surface of the cathode is hydrolyzed to generate hydroxyl and hydrogen. Under electromigration, chloride ions in the sample area fly ash slurry pass through the anion exchange membrane to the anode chamber. The chloride ions combine with the hydrogen ions to generate hydrogen chloride, and the hydrogen chloride reacts with the aluminum hydroxide to generate aluminum trichloride and water. The anion exchange membrane is effective to inhibit migration of aluminum ions to the sample area. Meanwhile, under the action of electromigration, silicate and hydroxide in the cathode chamber are transferred to the sample area to react with calcium in fly ash in the sample area to generate calcium silicate hydrate, and the hydroxide can be combined with calcium ions to generate calcium hydroxide. The acid leaching residue is mixed with water, and chloride ions adsorbed on the surface of the acid leaching residue can be removed in the stirring process. The water washing acid leaching residue is mixed with the electrically-driven silicon-carried fly ash slurry, and aluminum in the water washing acid leaching residue can react with calcium hydroxide and calcium silicate to generate hydrated calcium aluminate and calcium aluminosilicate geopolymer. And drying the aluminum chloride solution, wherein aluminum chloride is subjected to hydrolytic polymerization in the drying process to generate polyaluminum chloride.
The preparation process is simple, the high-strength brick and the polyaluminium chloride flocculating agent can be synchronously prepared by utilizing the waste incineration fly ash and the aluminium hydroxide and combining an electrolysis system, hydrogen ions and hydroxyl generated by the waste incineration fly ash, the aluminium hydroxide and electrode electrolysis water are completely utilized in the preparation process, other wastes are not generated, the maximum compression strength of the prepared high-strength brick can reach 48.17MPa, and the maximum content of the prepared polyaluminium chloride alumina can reach 51.75%.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A method for synchronously preparing waste incineration fly ash roadbed bricks and polyaluminium chloride is characterized by comprising the following steps:
respectively weighing water and waste incineration fly ash, mixing and stirring the water and the waste incineration fly ash into paste to obtain fly ash slurry, and filling the fly ash slurry into a sample area of an electrolytic cell;
adding aluminum hydroxide into the anode chamber of the electrolytic cell, and injecting water into the anode chamber until the water is flush with the fly ash slurry in the sample area;
dissolving sodium silicate in water to prepare a sodium silicate aqueous solution, and injecting the sodium silicate aqueous solution into a cathode chamber of an electrolytic cell until the sodium silicate aqueous solution is flush with fly ash slurry in a sample area;
connecting the anode and the cathode of the electrolytic cell with a direct current power supply, conducting acid immersion slurry out of the anode chamber after treating for 0.25-6 hours, and conducting electrically-driven silicon-loaded flying mortar out of the sample area;
filtering the acid leaching slurry to obtain a liquid part which is a chlorine-aluminum liquid and a solid part which is acid leaching residue;
respectively weighing water and acid leaching residues, mixing, stirring and filtering to obtain a solid part which is water washing acid leaching residues;
mixing the washing acid leaching residue and the electrically-driven silicon-loaded fly ash slurry, uniformly stirring, molding and maintaining to obtain the high-strength brick;
and drying the aluminum chloride solution, and grinding the aluminum chloride solution into powder to obtain the polyaluminum chloride.
2. The method for synchronously preparing the waste incineration fly ash roadbed brick and the polyaluminium chloride as claimed in claim 1, wherein the mass ratio of the aluminium hydroxide to the waste incineration fly ash is (7.5-60): 100.
3. the method for synchronously preparing the waste incineration fly ash roadbed brick and the polyaluminium chloride as claimed in claim 2, wherein the mass ratio of the aluminium hydroxide to the waste incineration fly ash is (15-45): 100.
4. the method for synchronously preparing the waste incineration fly ash roadbed brick and the polyaluminium chloride as claimed in claim 1, wherein the liquid-solid ratio of the water and the waste incineration fly ash which are respectively weighed is 0.25-0.45 mL/g.
5. The method for synchronously preparing the waste incineration fly ash roadbed brick and the polyaluminium chloride as claimed in claim 1, wherein the solid content of the sodium silicate aqueous solution is 5-40%.
6. The method for synchronously preparing the waste incineration fly ash roadbed brick and the polyaluminium chloride as claimed in claim 5, wherein the solid content of the sodium silicate aqueous solution is 10-40%.
7. The method for simultaneously preparing the waste incineration fly ash roadbed brick and the polyaluminium chloride according to claim 1, wherein the anode and the cathode of the electrolytic cell are connected with a direct current power supply, after 0.5-4.5 hours of treatment, the acid-leaching slurry is led out from the anode chamber, and the electrically-driven silicon-loaded fly ash slurry is led out from the sample area.
8. The method for synchronously preparing the waste incineration fly ash roadbed brick and the polyaluminium chloride according to the claim 1, wherein the voltage of the direct current power supply is 50-350V, and the current is 100-1000A.
9. The method for synchronously preparing the waste incineration fly ash roadbed brick and the polyaluminium chloride as claimed in claim 1, wherein the liquid-solid ratio of the water to the acid leaching residue which are respectively weighed is 1-3 mL/g.
10. The method for synchronously preparing the waste incineration fly ash roadbed brick and the polyaluminium chloride as claimed in claim 1, wherein the chlorine-aluminum liquid is dried at a temperature of 50-150 ℃.
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