TWI466712B - Treatment of fly ash and elimination agent for dioxins and leachable-metals in fly ash - Google Patents

Description

Fly ash recycling method, and used to remove dioxin homologues in fly ash and soluble Heavy metal remover

The invention relates to a method for recycling fly ash, in particular to a method for simultaneously processing dioxin homologues in fly ash and soluble heavy metals, reducing the content of dioxin homologues and soluble heavy metals in fly ash, so as to fly The dioxin homologue and the soluble heavy metal concentration contained in the ash can be reused below the regulatory standards.

Conventional technology uses solid waste incinerators (MSWI) to treat solid waste. Although solid waste can be reduced, the fly ash produced by incineration contains a variety of toxic substances. If the dioxin homologue or soluble heavy metal is dissolved in the environment without the treatment of fly ash, or if the fly ash is not recycled and reused directly, it will pollute the environment and seriously affect the health of the organism. Diaoxin homologues, which refer to polychlorinated dibenzo- p- dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and co-planar polychlorinated (Partially coplanar polychlorinated). Biphenyls) and other bioaccumulative toxic chemicals, and heavy metals are generally metal or metalloid elements that are significantly toxic to living things, such as cobalt, tin, cadmium, chromium, lead, arsenic, mercury, nickel, zinc or copper. .

In order to reduce the threat of toxic substances in the fly ash to the organism, the EPA stipulates that the toxic substances in the fly ash discharged from the solid waste incinerator must be lower than the concentration shown in Table 1, before the fly ash can be re-examined. use.

Since the physicochemical properties of the dioxin homologue and the soluble heavy metal are different, it is necessary to carry out different resource treatment procedures for the fly ash containing the dioxin homologue or the soluble heavy metal, in order to improve the dioxin homologue in the fly ash. Or the processing efficiency of heavy metals can be dissolved to carry out the reuse of fly ash.

The treatment of the conventional dioxin homologue thermally cleaves the dioxin homologue in the fly ash by high temperature incineration, which can directly break the bond and destroy the structure of the dioxin homologue, and reduce the toxic equivalent of the fly ash. However, conventional methods for treating dioxin homologues must provide a large amount of energy to be processed at temperatures up to 800 ° C to effectively destroy the chemical structure of the dioxin homologue to reduce its toxic equivalent. In addition, although the thermal cracking method can promote the dissociation of the soluble heavy metals in the organic matter, but can not further decompose the soluble heavy metals in the ionic state, the conventional method for treating the dioxin homologue cannot reduce the soluble heavy metals in the fly ash. The amount of solubles.

The conventional method for treating heavy metals is to remove the soluble heavy metals in the fly ash by using a metal chelating agent (such as EDTA) in combination with an organic solvent, dissolving the soluble heavy metals in the organic layer, and then removing the organic solvent. Get a recycled fly ash.

Conventional methods for treating heavy metals can use a large amount of organic solvents (such as alcohols). However, since the polarity of the organic solvent is very different from the polarity of the dioxin homologue, it is impossible to extract the dioxin homologue from the fly ash to the organic layer. Therefore, the conventional method for treating heavy metals can not simultaneously treat the dioxin homologue; in addition, the metal chelating agent is added to the organic solvent to help the metal chelating agent chelate with the soluble heavy metal, and the heavy metal can be dissolved. The organic layer is extracted to effectively reduce the amount of soluble heavy metal dissolved in the fly ash, however, the metal chelating agent reduces the solubility of the dioxin homologue in the organic solvent.

Therefore, whether it is a conventional method for treating dioxin homologues or a conventional method for treating heavy metals, it is impossible to simultaneously reduce the content of dioxin homologues and soluble heavy metals in fly ash to below the regulatory standards.

Please refer to the Patent Law No. 201016342 of the Republic of China on the treatment of waste or soil contaminated by heavy metals or dioxin, which is a method for removing the dioxin homologues and soluble heavy metals in fly ash, including the first The acid mixing step S91, a microwave heating step S92 and a water washing step S93 are shown.

The acid mixing step S91 is performed by mixing an acid solution such as sulfuric acid, hydrochloric acid or nitric acid with the fly ash; the microwave heating step S92 is to stably release heat energy by microwave heating to accelerate the decomposition efficiency of the toxic substance by the acid solution, and Destroying the dioxin homologue in the fly ash, and extracting the soluble heavy metal from the acid solution, so that the toxic substance content in the fly ash is lower than the regulatory standard, and then diluting the residual acid in the fly ash with the water washing step S93 After neutralization, the fly ash can be reused.

However, the microwave heating step S92 must provide an energy source to heat a large volume of acid solution, and the water washing step S93 must consume a large amount of water resources, and the treated acid liquid must still be treated with a precipitation step to treat the soluble heavy metal therein. It can be used to recover the acid solution, or the acid solution from which the heavy metal is removed can be diluted with water and discharged to the environment. Therefore, the treatment method disclosed in the patent case still requires a large amount of energy or water resources, which does not conform to the environmental protection concept of modern energy conservation and carbon reduction and cherish water resources.

Accordingly, it is necessary to provide a fly ash resource reduction method capable of simultaneously processing dioxin homologues in fly ash and soluble heavy metals, and capable of reducing energy and water resource consumption.

The main object of the present invention is to provide a method for recycling fly ash which is capable of improving the treatment efficiency of dioxin homologues and soluble heavy metals in fly ash.

A second object of the present invention is to provide a fly ash resource reduction method which is capable of reducing the consumption of organic solvents and water resources.

Another object of the present invention is to provide a remover for removing dioxin homologues and soluble heavy metals in fly ash, which is capable of simultaneously removing dioxin homologues and soluble heavy metal concentrations in fly ash.

The "flying ash" of the present invention is a fly ash containing a dioxin homologue and a heavy metal, or a bottom slag produced by heat treatment.

In order to achieve the foregoing object, the fly ash recycling method of the present invention comprises: a first-class washing step, wherein the fly ash is placed in a chamber, and a remover is introduced into the chamber to wash the fly ash, wherein The pressure inside the chamber is 200 to 350 bar, the temperature in the chamber is 40 to 120 ° C, the remover comprises a supercritical carbon dioxide fluid, a co-solvent and a metal adsorbent; and a displacement separation step is to pass a replacement fluid into the chamber In order to replace the remover in the chamber, the replacement fluid is separated from the fly ash.

In the fly ash recycling method of the present invention, the metal adsorbent may be selected from Bis- trifluoroethyldithiocarbamate (abbreviated as FDDC), Diethyldithiocarbamate (referred to as DDC), Dipropyl-dithiocarbamate (referred to as P3DC), Dibutyldithiocarbamate (abbreviated as BDC), and Dipentyldithiocarbamate (referred to as P5DC). , Dihexyldithiocarbamate (HDC) or Pyrrolidine-dithiocarbamate (referred to as PDC), Acetylacetone (AA), Trifluoroacetylacetone (TFA), Hexafluoroacetyl-acetone (HFA), Thenoyltrifluoroacetone (TTA) or Heptafluorobutanoyl-pivaroylmethane (FOD), Tributylphosphate (TBP), Tributylphosphine oxide (TBPO), Trioctylphosphine oxide (TOPO), Triphenyl-phosphine oxide (TPPO), Bis (2,4,4,-trimethylpentyl)phosphinic acid (Cyanex 272), Bis (2) , 4,4,-trimethyl-pentyl)dithiophosphinic acid (Cyanex 301 for short), Bis (2,4,4,-trimethylpentyl)monothiophosphinic acid (Cyanex 302 for short), Di(2-ethylhexyl)phosphoric acid (referred to as D ₂ EHPA for short) ) or Crown ether.

In the fly ash recycling method of the present invention, the metal adsorbent is more preferably Di(2-ethylhexyl)phosphoric acid.

In the method for recycling fly ash according to the present invention, the auxiliary solvent is preferably a low carbon number. The alkane or alcohol has a carbon number of 1 to 6, more preferably methanol or n-hexane.

In the method for recycling fly ash according to the present invention, the weight percentage of the auxiliary solvent to the remover is preferably 1.0 to 20.0%, and the weight percentage of the metal adsorbent to the remover is preferably 0.1 to 3.0%. The weight percentage of the carbon dioxide fluid to the remover is preferably from 79.9 to 98.9%.

A removing agent for removing dioxin homologues and soluble heavy metals in fly ash, comprising: 1.0% by weight to 20.0% by weight of a co-solvent; 0.1% to 3.0% by weight of a metal adsorbent; and 1 part by weight The percentage is 79.9 to 98.9% of supercritical carbon dioxide fluid.

In the removal agent for removing dioxin homologues and soluble heavy metals in fly ash, the metal adsorbent may be selected as Bis- trifluoro-ethyldithiocarbamate (abbreviated as FDDC), Diethyldithiocarbamate (referred to as DDC), and Dipropyldithiocarbamate (referred to as P3DC). Dibutyldithiocarbamate (BDC), Dipentyl-dithiocarbamate (P5DC), Dihexyldithiocarbamate (HDC) or Pyrrolidinedithiocarbamate (PDC), Acetylacetone (AA), Trifluoroacetylacetone (TFA), Hexafluoroacetylacetone (HFA), Thenoyl-trifluoroacetone (referred to as TTA) or Heptafluorobutanoyl-pivaroylmethane (FOD for short), Tributylphosphate (TBP), Tributylphosphine oxide (TBPO), Trioctyl-phosphine oxide (TOPO), Triphenylphosphine oxide (TPPO), Bis (2,4,4,-trimethylpentyl Phosphine acid (Cyanex 272), Bis (2,4,4,-trimethylpentyl)dithio- phosphinic acid (Cyanex 301), Bis (2,4,4,-trimethyl-pentyl)monothiophosphinic acid (Cyanex 302) , Di(2-ethylhexyl)phosphoric acid (referred to as D ₂ EHPA) or Crown e Ther.

In the remover for removing dioxin homologue and soluble heavy metal in the fly ash of the present invention, the metal adsorbent is more preferably Di(2-ethylhexyl)phosphoric acid.

In the remover for removing dioxin homologue and soluble heavy metal in fly ash, the auxiliary solvent is preferably a low carbon number alkane or an alcohol, and the carbon number is 1 to 6, and more preferably It is methanol or n-hexane.

The above and other objects, features and advantages of the present invention will become more <RTIgt; The fly ash recycling method of the present invention comprises: a first-class washing step S1 and a displacement separating step S2.

The flow washing step S1, the first-stage washing step, is to place the fly ash in a chamber, and a remover is introduced into the chamber to wash the fly ash, wherein the pressure in the chamber is 200-350 bar. The indoor temperature is 40-120 ° C, and the remover comprises a supercritical carbon dioxide fluid, a co-solvent and a metal adsorbent. More specifically, the pressure and temperature conditions of the chamber help to maintain the Polarity characteristics of the supercritical carbon dioxide fluid contained in the remover to dissolve the dioxin homologue in the fly ash. The auxiliary solvent is included to help dissolve the metal adsorbent, and by the temperature in the chamber, The pressure condition helps the metal adsorbent dissolve the soluble heavy metal ions in the fly ash in the auxiliary solvent, thereby desorbing the dioxin homologue and the soluble heavy metal ions in the fly ash, so as to adsorb on the fly ash. Dioxin homologues and soluble heavy metal content are reduced.

For example, the auxiliary solvent is used as a diluted solution of the metal adsorbent, and the auxiliary solvent is preferably a low carbon number (C1 to C6) alkane or an alcohol, particularly a dilution of methanol or n-hexane as a metal adsorbent. The solution not only helps to improve the adsorption of the metal adsorbent, but also helps to change the polar characteristics of the supercritical carbon dioxide fluid; the metal adsorbent can be selected as a metal chelate or coordinated organic compound, and the metal adsorbent can be substantially Divided into four categories: (1) dithiocarbamate metal adsorbents, (2) diketone metal adsorbents, (3) organophosphorus metal adsorbents and (4) macrocyclic Metal-like adsorbents.

Dithiocarbamic acid metal salts such adsorbents include: bis - dithio group trifluoride formate (Bis -trifluoroethyldithiocarbamate, referred FDDC), diethyl dithiocarbamate (Diethyldithiocarbamate, referred to as DDC), Dipropyldithiocarbamate (P3DC), Dibutyldithiocarbamate (BDC), Dipentyldithiocarbamate (P5DC) , Dihexyldithiocarbamate (HDC) or Pyrrolidine dithiocarbamate (PDC).

Diketone metal sorbents include, for example, 2,4-pentanedione (Acetylacetone, AA for short), 1,1,1-trifluoro-2,4-pentanedione (Trifluoroacetylacetone, abbreviated as TFA), Hexafluoroacetylacetone (HFA), 2-nophenytrifluoroacetone (TTA) or 2,2-dimethyl-6,6,7,7, 8,8,8,-Heptafluorobutanoyl-pivaroylmethane (FOD).

Organophosphorus metal adsorbents include, for example, Tributylphosphate (TBP), Tributylphosphine oxide (TBPO), Trioctylphosphine oxide (TOPO), and triphenylphosphine oxide. (Triphenylphosphine oxide, TPPO for short), Bis (2,4,4,-trimethylpentyl)phosphinic acid (Cyanex 272), 2,4,4- Bis (2,4,4,-trimethylpentyl)dithio-phosphinic acid (Cyanex 301), bis(2,4,4-trimethylpentyl)thiophosphinic acid ( Bis (2,4,4,-trimethyl-pentyl)monothiophosphinic acid, referred to as Cyanex 302) or Di(2-ethylhexyl)phosphoric acid (D ₂ EHPA for short).

A macrocyclic metal adsorbent, such as dicyclohexyl-18-crown-6 (referred to as DCH18C6).

The present invention can select an appropriate metal adsorbent according to the type of heavy metal to be treated; this embodiment is selected as D ₂ EHPA, and can be used with the supercritical carbon dioxide fluid and the auxiliary solvent to dissolve the heavy metal on the fly ash without It will reduce the effect of the original supercritical carbon dioxide fluid to dissolve the dioxin homologue, and maintain the efficiency of itself to adsorb metal ions.

The invention selects a carbon dioxide with a lower critical state to maintain lower conditions (Pro The boundary pressure of 72 bar and the critical temperature of 31.1 ° C), as the main solvent for dissolving the dioxin homologue, can reduce the energy consumption of preparing the supercritical fluid, and by controlling the pressure and temperature of the supercritical carbon dioxide fluid (pressure is 200~) 350 bar, temperature 40~120 ° C), adjust the polar characteristics of the supercritical carbon dioxide fluid, and can effectively and selectively dissolve the dioxin homologue; in addition, because carbon dioxide is easy to obtain, and its colorless, odorless, non-toxic It is non-explosive, non-flammable and non-corrosive, so it is safe.

In addition, the supercritical carbon dioxide fluid helps to uniformly contact the fly ash, and the metal ions in the organic state are released by the polarity of the supercritical carbon dioxide fluid, and the metal adsorbent captures the metal ions in the fly ash and dissolves In the auxiliary solvent. Thus, the fly ash recycling method of the present invention can not only effectively dissolve the dioxin homologue in the fly ash, but also improve the adsorption efficiency of the metal ions in the fly ash by the action of the metal adsorbent and the supercritical carbon dioxide fluid. The effect.

The displacement separation step S2 is to pass a replacement fluid into the chamber to replace the remover in the chamber and separate the replacement fluid from the fly ash. More specifically, the replacement fluid may be selected as a supercritical fluid. In this embodiment, the supercritical carbon dioxide fluid is selected to replace the remover in the chamber, and the supercritical carbon dioxide fluid is further reduced by reducing the pressure in the chamber. In the gas phase, the carbon dioxide gas can be directly discharged into the external environment or recovered after the carbon dioxide gas is recovered; in this embodiment, the pressure in the chamber is reduced to the same temperature as the temperature outside the chamber, and the carbon dioxide gas is directly discharged. Outside the room, the fly ash in the chamber has completed the removal of the dioxin homologue and soluble heavy metals.

Thus, the fly ash resource-recycling method of the present invention is capable of reducing organic dissolution The use of the agent, and does not require excessive energy to heat the fly ash and the remover, nor does it need to wash the fly ash by a large amount of aqueous solution, and further, the organic solvent is not retained in the recycled fly ash, and It can surely reduce the dioxin homologue and the soluble heavy metal content in the fly ash.

In order to prove the fly ash recycling method of the present invention, it is indeed possible to simultaneously treat the dioxin homologues in the fly ash and dissolve the heavy metals, and effectively reduce the content of the dioxin homologue contained in the fly ash, and reduce the ash in the fly ash. Dissolving and dissolving heavy metals. In this example, a fly ash sample containing dioxin homologs and several soluble heavy metals was obtained from the incinerator, and the following tests were carried out: (A) Analysis of the content of the dioxin homologue of the fly ash sample, (B) The soluble metal content of the fly ash sample was analyzed, (C) the different parameters were used to remove the dioxin homologue test in the fly ash sample, and (D) the different parameters were used to remove the soluble heavy metal test in the fly ash sample.

(A) Analysis of the content of dioxin homologues in fly ash samples

In this embodiment, the content of 17 dioxin homologues in the fly ash sample is analyzed by reference to the "Daisin and Furan Detection Method (NIEA M801.12B)" of the Republic of China Environmental Protection Agency, which uses a high-resolution gas phase. Chromatographic mass spectrometry (GC/MS) was analyzed by the Isotope dilution method.

Please refer to Table 2, where PeCDFs account for about 10% of the fly ash sample, HxCDFs account for about 19%, HpCDFs for about 22%, OCDF for about 8.97%, HpCCDs for about 7.53%, and OCDD for about 25%. One result shows that the dioxin homologue contained in the fly ash sample is mainly composed of 5 to 8 chlorine atoms. The dioxin homolog of the fly ash sample has a toxic equivalent of 35% of the total toxic equivalent, which is about 6.49 ng I-Teq/g.

According to the dioxin emission standard of the fixed pollution source announced by the Environmental Protection Agency of the Republic of China, the Environmental Protection Agency of the Republic of China (94), the dioxin content per unit weight of fly ash must be less than 1 ng/g. Fly ash is dumped in the environment or reused.

(B) Analysis of soluble heavy metal content in fly ash samples

This example refers to the “Environmental Waste Toxicity Characteristic Dissolution Procedure (NIEA R201.14C)” issued by the Republic of China Environmental Protection Agency, and is changed to the fly ash sample by inductively coupled plasma atomic emission spectrometer (ICP-OES). The heavy metal content can be dissolved for analysis. More specifically, 25 g of fly ash sample was extracted with 250 ml of acetic acid (pH 2.88) at room temperature for 18 hours, then the fly ash was filtered, and 1 ml of the extract was taken with 4 ml of nitric acid (69%) and 3 ml of hydrogen peroxide. After mixing, microwave digestion was carried out to obtain a digestive juice, and the content of soluble heavy metals such as cadmium, chromium, lead, arsenic, mercury, nickel, zinc and copper was analyzed by ICP-OES.

(C) Deionization of dioxin homologues in fly ash samples with different parameters

The present embodiment provides a supercritical fluid device as shown in FIG. 3, which comprises a mixing assembly 1, a pressure component 2 and a separation tank 3, and the mixing assembly 1 and the separation tank 3 are connected to each other, and The internal pressure of the mixing unit 1 and the separation tank 3 is controlled by the pressure unit 2.

The mixing assembly 1 is provided with a carbon dioxide tank 11, a auxiliary solvent tank 12 and a chamber 13. The carbon dioxide tank 11 and the auxiliary solvent tank 12 are connected to the chamber 13, and the carbon dioxide tank 11 is used for accommodating the super tank. a critical carbon dioxide fluid, the auxiliary solvent tank 12 is for accommodating the auxiliary solvent (such as methanol or n-hexane) and the metal adsorbent (such as E ₂ DHPA), and the chamber 13 is for accommodating a sample to be processed. The carbon dioxide tank 11 and the auxiliary solvent tank 12 have a function of adjusting the temperature and pressure inside the tank (heater H or cooler C as shown in the figure), and each of them is connected with an infusion pump P and a flow rate regulator F to be internal. The solution is sent to the chamber 13.

The pressure component 2 includes a first back pressure valve 21 and a second back pressure valve 22, wherein the first back pressure valve 21 controls the internal pressure of the chamber 13, and the second back pressure valve 22 controls the The internal pressure of the separation tank 3 is separated.

The separation tank 3 includes a first outlet 31 and a second outlet 32. The first outlet 31 is for gas to escape into the environment or a collection tank (not shown), and the second outlet 32 can The auxiliary solvent mixed with the waste flows out.

The operation of the supercritical fluid device of the present embodiment is as follows: a waste sample (this embodiment is a fly ash sample) is placed in the chamber 13, so that the temperature and pressure conditions of the chamber 13 reach a preset value, and then Adjusting the flow rate of the operating fluid into the chamber 13 to be 4.5 ml/min, and setting the operation time (for example, 3 to 6 hours) to start removing the dioxin homologue of the sample and dissolving the heavy metal; the operating fluid is from the chamber 13 Flowing into the separation tank 3, reducing the pressure of the separation tank 3 to 40 bar, vaporizing the supercritical carbon dioxide gas, the carbon dioxide gas can be recycled for reuse, or directly discharged into the environment; and the separation tank 3 is internally Then, a raffinate contains toxic substances such as dioxin homologues and soluble heavy metals, and the fly ash in the chamber 13 has removed dioxin homologs and soluble toxic substances such as heavy metals, and can be further use.

For example, in the present embodiment, the fly ash sample (about 110 g) is first placed in the chamber 13, and the supercritical carbon dioxide fluid (hereinafter referred to as CO _{2 (sf) is} referred to as the mixing ratio shown in the fourth table. _)), the solvent and the secondary metal sorbent after mixing, to 4.5ml / min flow rate of flow through the chamber 13, until the end of the mixing time of the fly ash sample was withdrawn, and the treated fly ash comparison sample of the untreated Total toxicity equivalent, calculate the dioxin removal rate for each group.

In the present embodiment, the dioxin removal rate of the group C4 is better in the eight groups of treatment conditions, and the toxicity equivalent can be reduced to 0.84 ng I-Teq/g. Comparing the groups C1 to C3, the dioxin removal rate is proportional to the temperature in the chamber 13, and the temperature is set above 40-120 ° C, and the dioxin removal rate can reach more than 65%; comparing the groups C2 and C5, Change the operation As the weight percentage of methanol in the fluid and the mixing time, the dioxin removal rate can reach 80% or more. Compared with the C7 group, the weight percentage of methanol is only 2.67%, and the dioxin removal rate is still equivalent to that of the C5 group; Comparing the C5 and C6 groups, the dioxin removal rate is proportional to the pressure in the chamber 13, and the pressure at 200-350 bar can achieve a dioxin removal rate of more than 75%. In the present embodiment, the C8 group replaced methanol with n-hexane, and the dioxin removal rate was also 58.4%.

Please refer to Figure 4 for the samples of the fly ash treated in Groups C1, C2 and C3 as shown in Table 4, and analyze the removal rate of 17 dioxin homologues by the test (A); The temperature in the chamber 13 is set at 40 to 120 ° C to obtain a dioxin removal rate of 60% or more.

Please refer to Figure 5 again, taking the samples of the fly ash processed in Groups C4, C5 and C6 as shown in Table 4, and taking a sample of fly ash (110 grams, this is Group C9) for only 6 kg. After methanol was immersed for 18 hours at room temperature, the 17 dioxin homologue removal rates were analyzed by the test (A). It can be seen that it is impossible to remove the dioxin homologue in the fly ash sample by simply immersing in methanol; while immersing in the supercritical carbon dioxide fluid can accelerate the contact efficiency of the auxiliary solvent with the fly ash, and can better help the dioxin in the fly ash. The source is dissolved in the supercritical carbon dioxide fluid and the auxiliary solvent, and in addition, the pressure in the chamber 13 is set at 200 to 350 bar to obtain a dioxin removal rate of 70% or more.

(D) Test of soluble heavy metals in fly ash samples with different parameters

In this embodiment, four sets of fly ash samples were taken for the analysis of soluble heavy metals by the method of test (B), wherein: Group D1 was subjected to Group 4, Group C7. The fly ash sample treated under the conditions, the D2 group, is the condition of the group C7, but the methanol is changed to n-hexane as the auxiliary solvent, and the D3 group is the fly ash sample processed by the condition of the fourth table, the group C4, The D4 group is a fly ash sample treated under the conditions of Group 4, Group C9. For the results, please refer to Table 5.

Through the treatment of Groups D1 to D4, since many of the oxidation states can be dissolved by the dissolution of heavy metal compounds into soluble heavy metal ions, the solubleness of the soluble heavy metals in some projects will increase; and in Groups D1 and D2 of this embodiment. After treatment, it is indeed possible to significantly reduce the amount of lead, mercury or zinc soluble.

For the recycling of fly ash, after the treatment by the method of the invention, the amount of dissolved solids in the whole soluble metal is significantly reduced, and as shown in Table 4 As shown in the results of Groups C1 and C2, the present invention can simultaneously reduce the content of the dioxin homologue and the soluble heavy metal in the fly ash, and select methanol according to the content of the dioxin homologue and the soluble heavy metal contained in the waste. Or n-hexane as a co-solvent can improve the efficiency of processing dioxin homologs or soluble heavy metals. From the above, it can be seen that the fly ash recycling method of the present invention can effectively improve the treatment efficiency of the dioxin homologue and the soluble heavy metal in the fly ash.

Accordingly, the method for recycling fly ash according to the present invention is capable of providing lower energy-consuming temperature and pressure conditions by using the supercritical carbon dioxide fluid, the auxiliary solvent and the metal adsorbent, and simultaneously treating the dioxin homologue in the waste. And soluble heavy metals, which have the effect of improving the processing efficiency of dioxin homologs and soluble heavy metals.

The fly ash resource recycling method of the invention can reduce the consumption of organic solvents and water resources, so as to achieve environmentally friendly and resource-saving effects.

The removing agent for removing the dioxin homologue and the soluble heavy metal in the fly ash of the invention can simultaneously remove the dioxin homologue and the soluble heavy metal concentration in the fly ash, and has the function of improving the dioxin homologue in the fly ash removal. The effect of dissolving heavy metal efficiency.

While the invention has been described in connection with the preferred embodiments described above, it is not intended to limit the scope of the invention. The technical scope of the invention is protected, and therefore the scope of the invention is defined by the scope of the appended claims.

[this invention]

S1‧‧·flow washing steps

S2‧‧‧ Displacement separation step

1‧‧‧Mixed components

11‧‧‧CO2 tank

12‧‧‧Separent solvent tank

13‧‧ ‧ room

2‧‧‧Pressure components

21‧‧‧First back pressure valve

22‧‧‧Second back pressure valve

3‧‧‧Separation tank

31‧‧‧ first exit

32‧‧‧second exit

C‧‧‧cooler

F‧‧‧Flow Regulator

H‧‧‧heater

P‧‧‧Infusion pump

[customary]

S91‧‧‧ mixing step

S92‧‧‧ microwave heating step

S93‧‧‧Washing steps

Figure 1: Block diagram of the conventional method of removing dioxin homologs and soluble heavy metals.

Figure 2 is a block diagram showing the steps of the fly ash resource utilization method of the present invention.

Figure 3: Schematic diagram of the configuration of the supercritical fluid device provided in this embodiment.

Fig. 4 is a line diagram showing the dioxin homologue removal rate of the groups C1 to C3 of the present Example.

Figure 5: A line diagram of the dioxin homologue removal rate in groups C4 to C6 and C9 of this example.

S1‧‧·flow washing steps

S2‧‧‧ Displacement separation step

Claims (3)

A fly ash resource recycling method comprises: a first-class washing step, wherein the fly ash is placed in a chamber, and a remover is introduced into the chamber to wash the fly ash, wherein the pressure in the chamber is 200-350 Bar, the temperature in the chamber is 40-120 ° C, the remover comprises a supercritical carbon dioxide fluid, a co-solvent and a metal adsorbent; and a displacement separation step is to pass a supercritical carbon dioxide fluid into the chamber. The supercritical carbon dioxide fluid is separated from the fly ash by replacing the remover in the chamber; wherein the metal adsorbent is di(2-ethylhexyl)phosphoric acid, and the auxiliary solvent is methanol or n-hexane. The method for recycling fly ash according to claim 1, wherein the auxiliary solvent accounts for 1.0-20.0% by weight of the remover, and the metal adsorbent accounts for 0.1% to 3.0% by weight of the remover. The supercritical carbon dioxide fluid accounts for 79.9 to 98.9% by weight of the remover. A removing agent for removing dioxin homologues and soluble heavy metals in fly ash, comprising: 1.0% by weight to 20.0% by weight of a co-solvent; 0.1% to 3.0% by weight of a metal adsorbent; and 1 part by weight The supercritical carbon dioxide fluid having a percentage of 79.9 to 98.9%; wherein the metal adsorbent is di(2-ethylhexyl)phosphoric acid; the auxiliary solvent is methanol or n-hexane.