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
• • 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
  • A62D2101/20—Organic substances
• • 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
  • A62D2101/20—Organic substances
  • A62D2101/22—Organic 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
  • A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
  • A62D2101/20—Organic substances
  • A62D2101/24—Organic substances containing heavy metals
• • 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
• • 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
  • A62D2101/45—Inorganic substances containing nitrogen or phosphorus
• • 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

Definitions

• the invention relates to a method for immobilizing ecologically harmful, organic or inorganic compounds, by mixing these compounds in the presence of water with a fixant which comprises an absorbent and allowing the mixture to set, after the addition of an inorganic hydraulic binder, to obtain a hard, stone-like material.
• Such a method is known from the European Patent No. 0 398 410 and comprises the use of a modified clay as an absorbent for absorbing organic molecules.
• the layer spacing of the clay layers first has to be increased, in order to obtain good absorption efficiency with respect to the absorption of organic molecules, whereas after absorption, in order to counteract leaching of the absorbed material, the layer spacing of the clay layers has to be reduced again.
• a modified clay is to be used for immobilizing a mixture of various organic and inorganic chemical compounds it is usually necessary for either a non-modified clay to be present at the same time or for the modified clay still to have non-modified sites suitable for absorption. This ensures that both hydrophobic and hydrophilic sites are available for binding various ecologically harmful compounds. In such cases it is therefore necessary to know in advance, reasonably accurately, the composition of the material to be immobilized. In practice this will, however, not always be the case.
• the invention is characterized in that the absorbent used in the fixant is optionally pretreated activated carbon, cellulose or a cellulose derivative.
• the absorbent used is preferably sulphurized activated carbon; according to an expedient embodiment an activated carbon sulphurized to approximately 5 % of sulphide.
• a material is found to be particularly suitable for binding various cations such as salts of cadmium, lead, copper, mercury and zinc.
• the activated carbon or cellulose has been found to be particularly suitable for binding mineral oil.
• the compressive strength of a sandy soil contaminated with mineral oil was found, after mixing with a cement and setting for 30 days, even to be much more favourable than that of a similar sample where instead of activated carbon bentonite had been used.
• the compressive strength of a set, stone-like material is related to the leaching values, in the sense that for a higher compressive strength a lower leaching value is obtained in leaching tests.
• the absorbent used is methyl cellulose.
• the fixant further comprises at least one coordination complex-forming agent which preferably serves for the formation of a coordination complex with organic and in particular aromatic compounds.
• Aromatic compounds present in the material to be immobilized then, on the one hand, can be fixed as a coordination complex and, on the other hand, be coupled as such or via said complex to or in the pores of the activated carbon or the cellulose derivative.
• the coordination complex-forming agents used are preferably a metal salt, in particular an iron, manganese or aluminium salt or a combination thereof.
• ions are found to be able, owing to their 3d electrons, to form a strong bond to the 7T electron cloud of aromatic compounds such as polycyclic aromatic hydrocarbons, PCBs and the like which are usually present as a microcontaminant, or a material contaminated with acid sludge, where up to tens of per cent of organic pollutants can be present.
• the iron salt used is preferably a ferrous or ferric salt, such as the sulphate, nitrate, halide or hydroxide.
• the manganese salt expediently is a sulphate, nitrate, oxide or halide; while the aluminium salt preferably is the sulphate, nitrate, oxide or halide.
• the aim of the method according to the invention is to immobilize ecologically harmful organic and inorganic compounds by fixing these compounds by means of a fixant and incorporating the product obtained in a cement matrix. It was found that leaching of a number of compounds can be considerably reduced by also incorporating an oxidant in the fixant. Persulphate and permanganate were found to give good results to this end.
• the fixant additionally to contain a calcium source, preferably consisting of gypsum or optionally slaked lime.
• a calcium source preferably consisting of gypsum or optionally slaked lime.
• the gypsum used can be the anhydrite, the hemihydrate or the dihydrate thereof.
• the inorganic hydraulic binder to be used in the present method is preferably selected from a cement, ground and optionally granulated blast furnace slags, ground and/or porous granulated steel slags, powder-coal fly ash, thermally treated paper residue or a mixture thereof.
• the invention further relates to a fixant suitable for use in the immobilization of ecologically harmful organic or inorganic compounds, said fixant being characterized in that it consists of up to 25 % by weight of an iron and/or cobalt salt, up to 25 % by weight of a manganese salt, from 15 to 60 % by weight of optionally sulphurized activated carbon, or a cellulose derivative, together with up to 25 % by weight of an oxidant.
• the fixant further contains up to 15 % by weight of an aluminium salt and, if desired, up to 40 % of a calcium source.
• the material to be investigated related to a sludge-like residue which contained approximately 20 % of oil-like compounds (mineral oil, volatile aromatic compounds), 35 % of water and 1 % of metallic mercury.
• the material was mixed with 35 % (per cent by weight) of a mixture whose composition is reproduced below:
• the material was allowed to set at room temperature for a period of 30 days.
• the result was a shaped product having a strength of 2.8 MPa which, when subjected to a leaching test (on crushed material) showed leaching of mercury of a few ppb and of oil-like components of only a few ppm.
• the material to be examined in this case related to a residue of extractive soil purification, which in addition to approximately 8 per cent of mineral oil contained a few hundred ppm of PAH, chlorinated solvents (tri, per), cadmium, mercury and arsenic, 1,300 ppm of zinc and 4,000 ppm of lead.
• the material further contained approximately 40 % of water.
• the material was mixed with 30 % of a mixture whose composition is reproduced below:
• compressive strengths were determined. A gave a compressive strength of 4.2 MPa, B gave a compressive strength of 3.8 MPa, and C gave a compressive strength of 1.5 MPa.
• fixant A comprising activated carbon
• fixant B comprising organophilic clay
• the leachability of the obtained products have also been investigated by means of the diffusion test. More specifically, the cumulative emissions over a period of 64 days of the relevant heavy metals and anions from the immobilisates A and B have been measured. The results thereof are given in table 3: The compressive strengths of the immobilisates A and B have also been measured after 3 days and after 28 days:

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• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Business, Economics & Management (AREA)
• Emergency Management (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Processing Of Solid Wastes (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=19863879

Family Applications (1)

Country Status (2)

Cited By (4)

Families Citing this family (1)

Citations (6)

• 1994
  • 1994-02-25 NL NL9400292A patent/NL9400292A/nl not_active Application Discontinuation
• 1995
  • 1995-02-23 EP EP95200451A patent/EP0669145A1/fr not_active Withdrawn

Patent Citations (6)

Non-Patent Citations (1)

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