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
  • A62D3/10—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by subjecting to electric or wave energy or particle or ionizing radiation
  • A62D3/11—Electrochemical processes, e.g. electrodialysis
• • 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
• • 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
  • A62D3/36—Detoxification by using acid or alkaline reagents
• • 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
  • A62D3/40—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by heating to effect chemical change, e.g. pyrolysis
• • 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
• • 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
  • A62D2101/40—Inorganic substances
  • A62D2101/43—Inorganic substances containing heavy metals, in the bonded or free state
• • 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
  • A62D2101/40—Inorganic substances
  • A62D2101/49—Inorganic substances containing halogen
• • 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
  • A62D2203/00—Aspects of processes for making harmful chemical substances harmless, or less harmful, by effecting chemical change in the substances
  • A62D2203/02—Combined processes involving two or more distinct steps covered by groups A62D3/10 - A62D3/40
• • 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
  • A62D2203/00—Aspects of processes for making harmful chemical substances harmless, or less harmful, by effecting chemical change in the substances
  • A62D2203/10—Apparatus specially adapted for treating harmful chemical agents; Details thereof

Definitions

• the present invention relates to a process for extracting heavy metals contained in fly ash and residues from the purification of smoke from an incineration oven. It also relates to an installation for the implementation of this process.
• the main treatment routes envisaged to solve this problem aim at the overall conditioning of waste.
• a known method includes the use of hydraulic binders to coat the REFIOM.
• the main defect of this technique is to use, in most cases, quantities of binders at least equal to the quantities of waste and therefore to generate an ultimate residue with a mass clearly greater than the mass of the initial waste. This process is described in document WO 87/04017.
• Another known method consists in conditioning the waste in a hydrocarbon binder or a resin.
• the main defect of the technique is identical to that encountered when using hydraulic binders, with a higher processing cost.
• Another known method uses the melting of the waste and / or its vitrification.
• the waste is brought to melting temperature, with the use of additives aimed on the one hand at lowering the melting temperature and on the other hand at improving the stability of the final waste (glass or ceramic).
• the same remark can be made as above with regard to the increase in mass of the final waste, a volu ic reduction being it possible with respect to the raw pulverulent waste.
• Another known method consists in mixing the waste with clinker and in carrying out the fusion of the whole. This way consists in mixing all of the REFIOM with a fraction, or even almost all of the bottom ash leaving the incineration oven. Then, the assembly is carried out in order to obtain a more stable overall waste. The problem here is just moved from REFIOM to bottom ash. If the regulations concerning the latter currently allow their reuse as backfill charges, it may change if this type of treatment is chosen, and lead to the obligation of classified landfill, of the waste resulting from the operation.
• a process proposes the merger of REFIOM.
• the fraction emitted that is to say evaporated
• the polluting fraction represents only a few percent of the REFIOM, this by preparing an ultimate waste more or less stabilized (durability of the matrices) of mass always greater than the initial waste.
• the present invention provides a much more satisfactory solution to the treatment of waste than the processes of the known art for the application of the new admission standards.
• the proposed process applies to solid waste containing chlorine in the form of alkaline chlorides (in particular chloride and calcium hydroxychloride) and metallic pollutants (heavy metals and toxic elements mentioned above) in moderate concentrations (some percent).
• REFIOM can be treated directly when it results from the simultaneous recovery of fly ash and products resulting from the neutralization reactions of acid gases contained in the flue gases from incineration (CaCl2, CaOHCl, etc.) carried out by the dry process, semi dry or semi wet.
• the waste is recovered separately (case where the neutralization reaction of the acid gases is carried out by the wet process), the two waste are mixed beforehand before applying the process of the invention.
• the subject of the invention is a process for the extraction of pollutants consisting of heavy metals and toxic elements contained in waste consisting of fly ash and smoke purification residues from an incineration oven, characterized in what it involves the following steps: - chlorination of waste,
• Another subject of the invention is an installation for implementing the method described above, characterized in that it comprises:
• a separation device for carrying out the separation step, - at least one grinder to carry out the fine grinding step,
• the waste can pass through a solid / gas separator and a desorption module to be degassed there.
• This solid / gas separator can be a multicyclone and the desorption module can be a transported bed reactor.
• the magnetic sorting device can comprise a cascade of separators with permanent magnets.
• Powdered waste (REFIOM) is treated in a first step in a chlorination reactor to undergo an over-chlorination operation since this waste already has significant chlorine contents.
• the operation is carried out in a reactor where the contact mode is gas / solid.
• This contact is for example provided by a transported bed reactor.
• the main objective of chlorination is to increase the content of metal chlorides. This operation is carried out at a temperature between 100 ° C and 300 ° C, at atmospheric pressure.
• Chlorination is carried out from concentrated hydrogen chloride. Its proportion in the gas used to carry out the chlorination operation is between 60% and 90%. As will be seen later, hydrogen chloride can be produced during a later stage of the process. The chlorine used can therefore only come from treated waste.
• the result of the chlorination operation is the neutralization of the excess lime used when controlling the incineration plant.
• the unreacted hydrogen chloride at the outlet of the chlorination reactor can advantageously be directed to a solid / gas separation unit aimed at recovering the hydrogen chloride.
• This separation unit may comprise a solid / gas separator proper (for example a multicyclone) supplying on the one hand gas containing hydrogen chloride and on the other hand a solid over-chlorinated residue.
• the gas leaving the solid / gas separator is sent to a gas treatment unit allowing the preparation of concentrated hydrochloric acid of technical quality.
• the overchlorinated solid residue then passes through a desorption module to continue the degassing operation.
• This desorption module is for example constituted by a second transported bed reactor operating with a neutral gas.
• the gas recovered during the desorption operation is also sent to the gas treatment unit.
• the over-chlorinated and degassed residues are then heat treated in a continuous feed furnace of the moving bed type, for example a screw furnace, at a temperature between 800 ° C. and 1200 ° C., under inert sweeping.
• Nitrogen can be used as an inert gas.
• the oven is used either under slight vacuum (from 10 to 500 mm of water column), or under partial vacuum (from 0.2 to 0.6 bar absolute). During this treatment, a more volatile fraction is emitted, which can represent between 10% to 25% by weight of the product obtained after the heat treatment.
• This fraction contains the metal chlorides of a majority of the undesirable elements mentioned above (Zn, Cd, Pb, Ni) as well as forms containing As and Hg, as well as a significant part of a mixture of alkali chlorides (in particular KC1 and NaCl) and finally a fraction of noncondensables resulting from partial decompositions.
• the volatile fraction is condensed in a cyclone type condenser with injection of cold inert gas (for example nitrogen) at the inlet of the vapors. After condensation, the fraction is treated in order to separate the forms containing the metals from the other constituents. This separation step is carried out for example after placing this fraction in concentrated solution. Separation can be achieved in several ways. One can operate by selective precipitation or by electrochemical treatment or even practice a separation on membrane.
• the main fraction (75% to 90% by weight) from the heat treatment passes through a grinder where it is reduced to powder, the grains of which are between 10 and 100 ⁇ m in diameter.
• This powder is then treated in a sulfation reactor.
• the purpose of sulfation is on the one hand to emit the chlorinating agent (hydrogen chloride) necessary for the superchlorination step and, on the other hand, to stabilize the final residue.
• This step is carried out using an H2O + SO3 mixture obtained by dissociation of sulfuric acid. It is carried out in a reactor or a series of gas / solid contact sulfation reactors.
• transport bed reactors operating in a temperature range from 400 ° C to 600 ° C.
• two reactors can be used: a reactor on the solid supply side operating with depletion of the active gas (purification of hydrogen chloride) and a downstream reactor operating in concentration, on the supply side with active gas.
• the solid product resulting from sulfation then undergoes magnetic sorting to extract the part with high magnetic susceptibility, that is to say that containing the iron still present and especially the chromium subject to regulation and which is not extracted during heat treatment.
• This high magnetic susceptibility part including chromium is then grouped with the residues from the volatile fraction and containing the other toxic waste.
• the final waste is thus obtained, thus containing all of the pollutants. What remains of the solid product from the sulfation step, free of pollutants, can no longer be considered as waste.
• the main advantage of the process according to the invention is that it concentrates the polluting fraction (including heavy metals), which makes it possible to limit the ultimate waste and to envisage recycling and recovery of this ultimate waste.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Business, Economics & Management (AREA)
• Emergency Management (AREA)
• Electrochemistry (AREA)
• Processing Of Solid Wastes (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

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• 1994
  • 1994-02-22 FR FR9401987A patent/FR2716392B1/fr not_active Expired - Fee Related
• 1995
  • 1995-02-21 WO PCT/FR1995/000200 patent/WO1995022373A1/fr not_active Ceased
  • 1995-02-21 ES ES95910578T patent/ES2121353T3/es not_active Expired - Lifetime
  • 1995-02-21 DE DE69503363T patent/DE69503363T2/de not_active Expired - Fee Related
  • 1995-02-21 EP EP95910578A patent/EP0746384B1/de not_active Expired - Lifetime

Non-Patent Citations (3)

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