WO2020084521A1 - Process for the abatement of the content of chlorides in the ashes from the incineration of waste - Google Patents

Process for the abatement of the content of chlorides in the ashes from the incineration of waste Download PDF

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Publication number
WO2020084521A1
WO2020084521A1 PCT/IB2019/059069 IB2019059069W WO2020084521A1 WO 2020084521 A1 WO2020084521 A1 WO 2020084521A1 IB 2019059069 W IB2019059069 W IB 2019059069W WO 2020084521 A1 WO2020084521 A1 WO 2020084521A1
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Prior art keywords
solution
waste
chlorides
sodium aluminate
obtaining
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Application number
PCT/IB2019/059069
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French (fr)
Inventor
Emmanouil VOLAKAKIS
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E.V.H. S.R.L. In Liquidazione
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Publication of WO2020084521A1 publication Critical patent/WO2020084521A1/en

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Classifications

    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
    • A62D3/00—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances
    • A62D3/30—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents
    • A62D3/33—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents by chemical fixing the harmful substance, e.g. by chelation or complexation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09B—DISPOSAL OF SOLID WASTE
    • B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
    • B09B3/20—Agglomeration, binding or encapsulation of solid waste
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09B—DISPOSAL OF SOLID WASTE
    • B09B5/00—Operations not covered by a single other subclass or by a single other group in this subclass
    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
    • A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
    • A62D2101/08—Toxic combustion residues, e.g. toxic substances contained in fly ash from waste incineration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09B—DISPOSAL OF SOLID WASTE
    • B09B2101/00—Type of solid waste
    • B09B2101/30—Incineration ashes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/52—Recovery of material from discharge tubes or lamps
    • 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
    • Y02W30/82—Recycling of waste of electrical or electronic equipment [WEEE]

Definitions

  • the present invention relates to a process for the reduction of the content of soluble chlorides in waste, and in particular in municipal solid waste, below the levels of law.
  • Soluble chlorides are a particularly difficult component to treat in the stabilisation of waste and contaminated lands.
  • chloride-containing waste is universally distributed and constitutes, together with medium and high activity nuclear waste, one of the most difficult components to manage.
  • waste containing soluble chlorides can be enumerated as follows:
  • the lands contaminated by chlorides represent a further problem: an example thereof are the lands that are salified due to ingress of sea water into the deep aquifers.
  • light ashes have a high chlorine content, which is poorly chemically linked to the other components of the ashes; if these ashes are simply accumulated or buried in dedicated sites, the action of atmospheric agents, in particular rain, can wash away the element and transfer it to the ground, leading to the pollution thereof.
  • light ashes typically have chloride contents that can vary between about 10% and 60% releasing in the elution tests between 7,000 ppm and over 100,000 ppm. For this reason, these materials are classified as hazardous, while those that release chlorides below the limits of 2,500 ppm during the elution tests are classified as non-hazardous.
  • the object of the present invention is to overcome the problems discussed above of the prior art, and in particular to provide a process and a composition for the abatement of the content of chlorides in the ashes from the incineration of waste and the fixing of said chlorides in the form of compounds that do not release chlorine following elution with water.
  • step b) adding to the solution obtained in step under point a) calcium oxide and/or hydroxide, (CaO and/or Ca(OH) 2 ), in a quantity such that the calcium in solution is comprised between 0.5% and 10.0% by weight with respect to NaAl0 2 , obtaining a liquid composition;
  • the present invention relates to a liquid composition containing sodium aluminate and calcium oxide or hydroxide, in which calcium is present in a quantity comprised between 0.5% and 10.0% by weight with respect to NaAl0 2 , which is used to treat ash from incineration of solid waste in the process described above.
  • Fig. 1 represents schematically in the form of a flowchart the main process steps for the production of the aqueous solution of NaAl0 2 according to a preferred embodiment of the invention
  • Fig. 2 reproduces a photomicrograph obtained with a scanning electron microscope (SEM) of a sample of ash from incineration of solid waste, in which a sodium chloride crystal is highlighted;
  • - Fig. 3 reproduces a SEM photomicrograph of crystals obtained after the treatment of the ashes of Fig. 1 with the liquid composition of the invention
  • Fig. 4 reproduces a SEM photomicrograph of zeolite crystals obtained as a second product of the process of the preferred embodiment of the invention the scheme of which is illustrated in Fig. 1.
  • the first step of the process of the invention, a), consists in the preparation of an aqueous solution of sodium aluminate, NaAl0 2 ; in aqueous solution, sodium aluminate gives rise to the hydrated species NaAl(OH) 4 , but for simplicity’s sake in the rest of the text and of the claims, reference will always be made to the NaAl0 2 species, also to indicate or calculate concentrations, percentages and ratios by weight concerning this component.
  • the aqueous solution of NaAl0 2 can be prepared by dissolving metallic aluminum (preferably in powder or granular to accelerate the dissolution times) in an aqueous solution of soda, NaOH, in a molar ratio AkNaOH 1:1, equivalent to the atomic ratio between Na and Al; in the plant practice it is more common to use ratios by weight, and in this case the correct ratio between the two components is obtained by calculating the quantity by weight of NaOH present in the initial solution, and adding a quantity of metallic aluminum equal to 0.675 times the weight of NaOH (measured as a solid).
  • the reaction is strongly exothermic, especially if the metallic aluminum is used in a finely divided form, and as is known it involves the development of large quantities of gaseous hydrogen, so it must be carried out in specific environments with the possibility of controlling the development of gas.
  • the sodium aluminate solution is in turn obtained from a residue of another process for disposing of special waste.
  • the caustic attack of the glass of CRTs produces high volumes of alkaline silicate solutions; for example, in the case of attack of the glass with soda, solutions containing sodium silicate, Na 2 Si0 3 , as the main component are produced, in addition to other elements derived from the initial glass, and excess NaOH; these solutions, with a not exactly defined chemical composition, are indicated in the field with the term "waterglass", and in the case in particular of solutions derived from dissolution of the glasses of the CRTs, they contain various metals as impurities the main ones of which are zinc, strontium, barium and antimony. Due to the presence of these metals, which are difficult to separate from the waterglass (in particular, it is almost impossible to separate antimony), these solutions are in turn classified as hazardous waste and must be either inerted for disposal, or reused in others process.
  • the solutions of alkaline silicates derived from CRT disposal are used as a raw material for the preparation of the sodium aluminate solution.
  • the sodium aluminate solution of point a) is obtained according to the following steps:
  • step iii) washing with water of the solid gel phase obtained in step ii), obtaining a basic solution containing soda, and physical separation of this solution from the solid gel phase of sodium aluminosilicate;
  • step iv) after titration of the soda in the solution obtained in step iii), addition of metallic aluminum to said soda solution), with the formation of a sodium aluminate solution.
  • This alternative way of obtaining the sodium aluminate solution, to be used in step under point a) of the process of the invention, is preferred because it allows combining, in the formation of a single inertised residue, ashes of waste and a residue of industrial productions, both classified as such hazardous to require special treatments for their disposal.
  • a liquid composition is formed by adding calcium oxide and/or hydroxide to the solution of step a), in a quantity such that calcium is comprised between 0.5% and 10% by weight with respect to NaAl0 2 .
  • calcium is eventually present as hydroxide, Ca(OH) 2 , whether it has been added in the form of oxide or added as hydroxide.
  • the obtained liquid composition has a calcium content that is variable within the relatively wide limits indicated above, so as to take into account the fact that in many cases the ashes to be treated already have a significant Ca content which is available for the reaction.
  • the third step of the process of the invention, c), consists in treating ash from incineration of solid waste with the liquid composition obtained in step under point b).
  • Chlorides are generally present in the ashes from incineration of waste in the form of alkali metal salts, typically sodium or potassium chloride; the SEM photomicrograph of Fig. 2 shows an essentially cubic sodium chloride crystal, with side of approximately 2 pm, present in ashes from waste.
  • Fig. 3 reproduces a SEM photomicrograph of Friedel salt crystals, of lamellar shape, obtained after the treatment of the ashes of Fig. 2 with the liquid composition of the invention obtained in step b).
  • the Friedel salt effectively fixes the chlorine ions, and elution tests on the ashes treated according to the process of the invention have given rise to releases well below the 2500 ppm limit of chlorine set by regulations for the waste to be classified as non- hazardous, as shown in the experimental part.
  • Another advantage of the invention in this preferred embodiment is that in the solid phase of sodium aluminate which is separated in step iii) the heavy metals present in the initial glass remain trapped, i.e. especially zinc, strontium, barium and, above all, antimony.
  • this sodium aluminate which also contains other residual metals from the disposal of CRTs, forms a Faujasite-type acid zeolite that can have various industrial uses, including for example as a support for catalysts to be used in the petrochemical industry.
  • Figure 4 shows a SEM photomicrograph of the zeolite crystals obtained from the process.
  • the present invention relates to a liquid composition containing sodium aluminate and calcium oxide or hydroxide, in which calcium is present in a quantity comprised between 0.5% and 10.0% by weight with respect to NaAl0 2 , which is used to treat ash from incineration of solid waste in the process described above.

Abstract

A process is described that allows reducing below legal levels the content of chlorides in the ashes derived from the incineration of waste, in particular municipal solid waste, consisting in bringing said ashes into contact with a solution of sodium aluminate and calcium oxide or hydroxide. In a preferred embodiment of the invention, a solid phase of sodium alumosilicate containing metal impurities, particularly antimony, is obtained as a by-product of the process which phase, if treated in an autoclave forms an acid zeolite useful as a support for catalysts.

Description

PROCESS FOR THE ABATEMENT OF THE CONTENT OF CHLORIDES IN THE ASHES FROM THE INCINERATION OF WASTE
Figure imgf000003_0001
FIELD OF THE INVENTION
The present invention relates to a process for the reduction of the content of soluble chlorides in waste, and in particular in municipal solid waste, below the levels of law.
In recent years, the fraction of solid waste that is treated in incinerators has been increasing in Europe; on the one hand, this trend is due to the energy recovery allowed by the combustion of waste (waste-to-energy) and on the other to the increasing difficulties of finding new sites for waste landfills.
Soluble chlorides are a particularly difficult component to treat in the stabilisation of waste and contaminated lands. In the world, chloride-containing waste is universally distributed and constitutes, together with medium and high activity nuclear waste, one of the most difficult components to manage. At present, waste containing soluble chlorides can be enumerated as follows:
- ashes from incineration of municipal solid waste (containing 15 to 35% of soluble chlorides);
- saline slag from aluminum production (containing 20 to 50% of soluble chlorides);
- industrial wastewater treatment sludge (especially in petrochemical areas, containing 10 to 30% of soluble chlorides);
- sludge from the softening of desalted waters (containing up to 70% of soluble chlorides);
- drilling and fracking sludge (containing 5 to 35% of soluble chlorides).
In addition to waste, the lands contaminated by chlorides represent a further problem: an example thereof are the lands that are salified due to ingress of sea water into the deep aquifers.
In the present description reference will be made in particular to the treatment of ashes from the incineration of municipal solid waste, but the invention is of general applicability to all afore mentioned types of chlorides-containing waste.
In the incineration of waste, a part is converted into gaseous compounds that are released into the atmosphere (after treatments for the abatement of harmful compounds), while the non-gasified part gives rise to heavy slag (indicated in the sector also with the term“incineration bottom ash” or IBA), sludge, and light ashes (also referred to as“fly ash”).
The solid residues of waste incineration should be subsequently disposed of in a sustainable manner, if this were not extremely difficult due to their peculiar physico chemical characteristics, which make the diffusibility into the environment of the toxic substances they contain practically inevitable.
In particular, light ashes have a high chlorine content, which is poorly chemically linked to the other components of the ashes; if these ashes are simply accumulated or buried in dedicated sites, the action of atmospheric agents, in particular rain, can wash away the element and transfer it to the ground, leading to the pollution thereof.
Typically, light ashes have chloride contents that can vary between about 10% and 60% releasing in the elution tests between 7,000 ppm and over 100,000 ppm. For this reason, these materials are classified as hazardous, while those that release chlorides below the limits of 2,500 ppm during the elution tests are classified as non-hazardous.
Since most of the inorganic chlorides are soluble to a greater or lesser extent, to date no reliable methodology has been identified to block this element.
The object of the present invention is to overcome the problems discussed above of the prior art, and in particular to provide a process and a composition for the abatement of the content of chlorides in the ashes from the incineration of waste and the fixing of said chlorides in the form of compounds that do not release chlorine following elution with water.
SUMMARY OF THE INVENTION
These objects are obtained according to the present invention which, in a first aspect thereof, relates to a process for the abatement of the content of chlorides in waste and the fixing of said chlorides in the form of compounds that do not release chlorine following elution with water, which comprises the following steps:
a) obtaining an aqueous solution of sodium aluminate, NaAl02;
b) adding to the solution obtained in step under point a) calcium oxide and/or hydroxide, (CaO and/or Ca(OH)2), in a quantity such that the calcium in solution is comprised between 0.5% and 10.0% by weight with respect to NaAl02, obtaining a liquid composition;
c) treating ash from incineration of solid waste, by mixing with the liquid composition obtained in step under point b), obtaining the Friedel salt of formula Ca2Al(0H)6(Cl,0H)-2H20. In a second aspect thereof, the present invention relates to a liquid composition containing sodium aluminate and calcium oxide or hydroxide, in which calcium is present in a quantity comprised between 0.5% and 10.0% by weight with respect to NaAl02, which is used to treat ash from incineration of solid waste in the process described above.
BRIEF DESCRIPTION OF THE DRAWINGS
- Fig. 1 represents schematically in the form of a flowchart the main process steps for the production of the aqueous solution of NaAl02 according to a preferred embodiment of the invention;
- Fig. 2 reproduces a photomicrograph obtained with a scanning electron microscope (SEM) of a sample of ash from incineration of solid waste, in which a sodium chloride crystal is highlighted;
- Fig. 3 reproduces a SEM photomicrograph of crystals obtained after the treatment of the ashes of Fig. 1 with the liquid composition of the invention;
- Fig. 4 reproduces a SEM photomicrograph of zeolite crystals obtained as a second product of the process of the preferred embodiment of the invention the scheme of which is illustrated in Fig. 1.
DETAILED DESCRIPTION OF THE INVENTION
The first step of the process of the invention, a), consists in the preparation of an aqueous solution of sodium aluminate, NaAl02; in aqueous solution, sodium aluminate gives rise to the hydrated species NaAl(OH)4, but for simplicity’s sake in the rest of the text and of the claims, reference will always be made to the NaAl02 species, also to indicate or calculate concentrations, percentages and ratios by weight concerning this component.
The aqueous solution of NaAl02 can be prepared by dissolving metallic aluminum (preferably in powder or granular to accelerate the dissolution times) in an aqueous solution of soda, NaOH, in a molar ratio AkNaOH 1:1, equivalent to the atomic ratio between Na and Al; in the plant practice it is more common to use ratios by weight, and in this case the correct ratio between the two components is obtained by calculating the quantity by weight of NaOH present in the initial solution, and adding a quantity of metallic aluminum equal to 0.675 times the weight of NaOH (measured as a solid). The reaction is strongly exothermic, especially if the metallic aluminum is used in a finely divided form, and as is known it involves the development of large quantities of gaseous hydrogen, so it must be carried out in specific environments with the possibility of controlling the development of gas.
In an alternative and preferred embodiment of the invention, the sodium aluminate solution is in turn obtained from a residue of another process for disposing of special waste.
As is known, the rapid abandonment of television sets based on cathode ray tube (CRT) technology initiated in the early 2000s, entailed the need to dispose of enormous quantities of glasses containing high percentages of lead, which due to the toxicity of this element could not be disposed of in landfills and had to be treated so as to fix lead and prevent it from being released into the environment. For this purpose, various industrial processes have been developed, which normally provide as a first step the solubilization of lead-containing glass through caustic attacks, possibly at high temperatures in an autoclave; an example of treatments of this type is described in patent application WO 2017/162757 Al in the name of the Applicant. The caustic attack of the glass of CRTs produces high volumes of alkaline silicate solutions; for example, in the case of attack of the glass with soda, solutions containing sodium silicate, Na2Si03, as the main component are produced, in addition to other elements derived from the initial glass, and excess NaOH; these solutions, with a not exactly defined chemical composition, are indicated in the field with the term "waterglass", and in the case in particular of solutions derived from dissolution of the glasses of the CRTs, they contain various metals as impurities the main ones of which are zinc, strontium, barium and antimony. Due to the presence of these metals, which are difficult to separate from the waterglass (in particular, it is almost impossible to separate antimony), these solutions are in turn classified as hazardous waste and must be either inerted for disposal, or reused in others process.
In the case of the present invention, the solutions of alkaline silicates derived from CRT disposal are used as a raw material for the preparation of the sodium aluminate solution.
According to this alternative and preferred embodiment of the invention, the sodium aluminate solution of point a) is obtained according to the following steps:
i) recovery of a sodium silicate solution obtained by dissolving a lead-containing glass with NaOH; the liquid silicate thus obtained has a silica/alkali ratio comprised between 1.6 and 2 which is measured; it is therefore possible to calculate the weight value of Al to be used in step ii); and, on the basis of the production targets, also change the silica/alkali ratio; ii) addition of metallic aluminum to the solution of step i), obtaining a solid gel phase of sodium aluminosilicate, rich in soda, in which the metal impurities originally present in the lead-containing glass are fixed;
iii) washing with water of the solid gel phase obtained in step ii), obtaining a basic solution containing soda, and physical separation of this solution from the solid gel phase of sodium aluminosilicate;
iv) after titration of the soda in the solution obtained in step iii), addition of metallic aluminum to said soda solution), with the formation of a sodium aluminate solution.
This alternative way of obtaining the sodium aluminate solution, to be used in step under point a) of the process of the invention, is preferred because it allows combining, in the formation of a single inertised residue, ashes of waste and a residue of industrial productions, both classified as such hazardous to require special treatments for their disposal.
In the second step of the process of the invention, b), a liquid composition is formed by adding calcium oxide and/or hydroxide to the solution of step a), in a quantity such that calcium is comprised between 0.5% and 10% by weight with respect to NaAl02. In the liquid composition, calcium is eventually present as hydroxide, Ca(OH)2, whether it has been added in the form of oxide or added as hydroxide.
The obtained liquid composition has a calcium content that is variable within the relatively wide limits indicated above, so as to take into account the fact that in many cases the ashes to be treated already have a significant Ca content which is available for the reaction. For the optimal realization of the invention, therefore, it is preferable to carry out a quick chemical analysis of a sample of ashes to determine the calcium content thereof, and to adjust the quantity of CaO and/or Ca(OH)2 intentionally added in step b), within the aforesaid range, in order to obtain a liquid composition with a calcium content close to that required by the Friedel salt stoichiometry.
The third step of the process of the invention, c), consists in treating ash from incineration of solid waste with the liquid composition obtained in step under point b).
Chlorides are generally present in the ashes from incineration of waste in the form of alkali metal salts, typically sodium or potassium chloride; the SEM photomicrograph of Fig. 2 shows an essentially cubic sodium chloride crystal, with side of approximately 2 pm, present in ashes from waste. Although the reaction mechanism has not been studied in detail with the methods of chemical kinetics, the inventors believe that by putting the ashes containing chlorides in contact with the solution containing calcium hydroxide and sodium aluminate, the reaction occurs first between the alkaline halide and the calcium hydroxide to form calcium chloride, which then reacts very quickly with sodium aluminate to form the Friedel salt, of formula Ca2Al(0H)6(Cl,0H)-2H20, in which chlorine is firmly fixed.
The sequence of reactions is extremely rapid: the slow step is the formation of calcium chloride, due to the not very high solubility of calcium hydroxide, which is favoured by increasing the quantity of water; as soon as calcium chloride is formed, the reaction thereof with sodium aluminate takes place at high speed to form the Friedel salt which also incorporates a lot of water, thus also compensating for the dilution required to accelerate the reaction for the formation of calcium chloride. Fig. 3 reproduces a SEM photomicrograph of Friedel salt crystals, of lamellar shape, obtained after the treatment of the ashes of Fig. 2 with the liquid composition of the invention obtained in step b).
The Friedel salt effectively fixes the chlorine ions, and elution tests on the ashes treated according to the process of the invention have given rise to releases well below the 2500 ppm limit of chlorine set by regulations for the waste to be classified as non- hazardous, as shown in the experimental part.
With the method of the invention, the fixing of chlorides in stable form in the Friedel salt is obtained relatively quickly, and is completed within 24-48 hours.
Another advantage of the invention in this preferred embodiment is that in the solid phase of sodium aluminate which is separated in step iii) the heavy metals present in the initial glass remain trapped, i.e. especially zinc, strontium, barium and, above all, antimony. The inventors have found that following treatment in an autoclave at temperatures higher than 100 °C, this sodium aluminate, which also contains other residual metals from the disposal of CRTs, forms a Faujasite-type acid zeolite that can have various industrial uses, including for example as a support for catalysts to be used in the petrochemical industry. Figure 4 shows a SEM photomicrograph of the zeolite crystals obtained from the process.
In a second aspect thereof, the present invention relates to a liquid composition containing sodium aluminate and calcium oxide or hydroxide, in which calcium is present in a quantity comprised between 0.5% and 10.0% by weight with respect to NaAl02, which is used to treat ash from incineration of solid waste in the process described above.

Claims

1. Process for the abatement of the content of chlorides in waste and the fixing of said chlorides in the form of compounds that do not release chlorine following elution with water, which includes the following steps:
a) obtaining an aqueous solution of sodium aluminate, NaAl02;
b) adding to the solution obtained in step under point a) calcium oxide and/or hydroxide (CaO and/or Ca(OH)2), in a quantity such that calcium in solution is comprised between 0.5% and 10.0% by weight with respect to NaAl02, obtaining a liquid composition;
c) treatment of ash from incineration of solid waste, by mixing with the liquid composition obtained in step under point b), obtaining the Friedel salt of formula Ca2Al(OH)6(Cl,OH) 2H20.
2. Process according to claim 1, in which the aqueous sodium aluminate solution of step a) is prepared by dissolving metallic aluminum in an aqueous solution of soda, NaOH, in a molar ratio AhNaOH 1:1.
3. Process according to claim 1, in which the aqueous sodium aluminate solution of step a) is produced according to the following steps:
i) recovery of a sodium silicate solution obtained by dissolving a lead-containing glass with NaOH; the liquid silicate thus obtained has a silica/alkali ratio comprised between 1.6 and 2 which is measured; it is therefore possible to calculate the weight value of Al to be used in step ii);
ii) addition of metallic aluminum to the solution of step i), obtaining a solid gel phase of sodium aluminosilicate, in which the metal impurities originally present in the lead-containing glass are fixed;
iii) washing with water of the solid gel phase obtained in step ii), obtaining a basic solution containing soda, and physical separation of this solution from the solid gel phase of sodium aluminosilicate;
iv) after titration of the soda in the solution obtained in step iii), addition of metallic aluminum to said soda solution, with the formation of a sodium aluminate solution.
4. Process according to claim 3, in which the solid gel phase of sodium aluminosilicate separated in step iii) is treated in an autoclave at a temperature higher than 100 °C producing a Faujasite-type zeolite containing the metal impurities originally present in the lead-containing glass.
5. A liquid composition containing sodium aluminate and calcium oxide and/or hydroxide, in which calcium is present in a quantity comprised between 0.5% and 10.0% by weight with respect to NaAl02.
PCT/IB2019/059069 2018-10-23 2019-10-23 Process for the abatement of the content of chlorides in the ashes from the incineration of waste WO2020084521A1 (en)

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
CN111774404A (en) * 2020-07-04 2020-10-16 上海和惠生态环境科技有限公司 Efficient washing dechlorination process and device for household garbage incineration fly ash
CN114032391A (en) * 2021-10-29 2022-02-11 天津城建大学 High-value utilization method of waste incineration fly ash prepared based on catalyst

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JP2000037676A (en) * 1998-07-23 2000-02-08 Sumitomo Metal Ind Ltd Stabilization treatment of waste containing heavy metal
TW201208990A (en) * 2010-08-17 2012-03-01 Univ Nat Taipei Technology Processing method for chlorine-containing waste water
WO2017162757A1 (en) * 2016-03-24 2017-09-28 E.V.H. S.r.l. Process for the treatment of end-of-life cathode-ray tubes

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Publication number Priority date Publication date Assignee Title
EP0547923A1 (en) * 1991-12-18 1993-06-23 Compagnie Du Sol Process for stabilising and solidifying incineration products of municipal waste, products resulting from this process and products for its implementation
JP2000037676A (en) * 1998-07-23 2000-02-08 Sumitomo Metal Ind Ltd Stabilization treatment of waste containing heavy metal
TW201208990A (en) * 2010-08-17 2012-03-01 Univ Nat Taipei Technology Processing method for chlorine-containing waste water
WO2017162757A1 (en) * 2016-03-24 2017-09-28 E.V.H. S.r.l. Process for the treatment of end-of-life cathode-ray tubes

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111774404A (en) * 2020-07-04 2020-10-16 上海和惠生态环境科技有限公司 Efficient washing dechlorination process and device for household garbage incineration fly ash
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