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
  • A62D3/36—Detoxification by using acid or alkaline reagents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
  • B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
  • B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
  • B09B3/0066—Disposal of asbestos
• • 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
  • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B18/04—Waste materials; Refuse
  • C04B18/0475—Waste asbestos
• • 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
  • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B18/04—Waste materials; Refuse
  • C04B18/0481—Other specific industrial waste materials not provided for elsewhere in C04B18/00
• • 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
  • A62D2101/41—Inorganic fibres, e.g. asbestos
• • 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
  • Y02W30/58—Construction or demolition [C&D] waste
• • 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

Definitions

• the present invention relates to a method according to the preamble of claim 1 for disposing of and neutralizing asbestos-containing waste.
• asbestos-containing waste is contacted with an acid capable of dissolving the asbestos, or with a salt thereof.
• Solvay scrubchemie GmbH has applied for a patent for a method for the disposal of asbestos, the method being based on dissolving the asbestos in acidic saline solutions containing hydrofluoric acid and/or fluorine (Published EP Application No. 0,559,051).
• the publication also discloses a method for emptying an acetylene cylinder of acetone and residual acetylene, whereby gases and fumes are sucked through a particle filter and a gas conditioner into the ambient air using a vacuum pump.
• a hydrofluoric acid compound or derivative capable of dissolving asbestos and cement is introduced into the cylinder. After dissolution, the cylinder is emptied of dissolved material and acid suspension by pumping. The cylinder metal is recovered and recycled.
• An economically attractive system for the disposal ofthe asbestos in acetylene cylinders must understandably be functional and environmentally friendly, preferably such that the cylinders remain undamaged.
• the above-described solution provides environmentally detrimental fluorine-containing waste.
• the cylinders remain undamaged but are not used as pressure vessels; instead, they are scrapped. Furthermore, it has proved difficult to scrape the bottles empty in the manner suggested in the prior art method.
• the present invention seeks to remove the drawbacks hampering the prior art and to provide a novel method for the disposal of asbestos-containing waste.
• the dissolution of asbestos in hydrochloric acid can be greatly accelerated by introducing potassium ions into the hydrochloric acid in the form of a potassium compound or salt.
• the present invention is based on the concept of dissolving the asbestos in hydrochloric acid, whereby a suitable potassium salt has been added to the hydrochloric acid in an amount of about 0.1 to about 20 %, preferably about 0.5 to about 10 % calculated on the basis of concentrated (100 %) hydrochloric acid.
• the amount of potassium in the solution varies according to the salt, but generally speaking, the molar ratio (M K M C1) of the potassium and the chlorine in the hydrochloric acid should be in the range 0.001 to 0.01, preferably about 0.002 to 0.05.
• the invention is characterized by what is stated in the characterizing part of claim 1.
• the invention can be applied to, e.g. taking apart acetylene cylinders and neutralizing the asbestos/cement material in the cylinders.
• the treatment of acetylene cylinders containing asbestos comprises the following steps:
• the cylinder is cut in two using a lathe or the like, such that the tool cuts through the metal casing only,
• the material removed from the bottle is brought to the above-described hydrochloric acid solution directly using the sleeve or via an intermediate storage step.
• the hydrochloric acid (HCl) used for dissolving the asbestos is advantageously fairly concentrated; typically, the aqueous solution contains at least 10 % by weight of hydrochloric acid.
• a hydrochloric acid of as high a concentration as possible is used, in particular a concentration of approximately 20 to 40 %.
• a potassium salt or compound is added into the hydrochloric acid at a suitable treatment stage.
• Inorganic potassium salts of advantage comprise potassium sulphate, potassium chloride, potassium nitrate, potassium carbonate and potassium phosphate.
• the potassium salt can be added to the hydrochloric acid prior to the outset ofthe treatment or during the treatment.
• adding a potassium compound (that is, potassium ions) into the acid enhances the dissolution ofthe asbestos, but it has also been found that adding other mineral acids further accelerates the dissolution ofthe asbestos fibres.
• Such other mineral acids comprise, among others, phosphoric acid and nitric acid. They are (each) typically present in an amount of about 0.1 to 10 % by weight based on the amount of hydrochloric acid (calculated as 100 % hydrochloric acid).
• the dissolution of asbestos-containing waste is advantageously carried out at an elevated temperature of about 30 to 95 °C, preferably about 40 to about 80 °C, under stirring.
• the treatment time depends on the amount of asbestos but, generally speaking, a treatment of 1 min to 24 hrs, preferably about 10 min to 4 hrs, will suffice.
• the present method can be applied to the treatment of asbestos-containing waste from different sources, including, for instance, asbestos waste from thermal and electric insulation in buildings, electric devices and discarded gas cylinders.
• the method ofthe invention is applied expressly to emptying acetylene cylinders and to rendering the asbestos contained therein harmless.
• This type of asbestos material usually contains some cement which is readily soluble in hydrochloric acid.
• the gas cylinder is evacuated by means of underpressure, the valve is removed and the cylinder is cut in two in a lathe or a corresponding device.
• a plastic sleeve or a co ⁇ esponding elastic obstruction fully blocking the advance of dust is pulled over the longer half of the cylinder.
• All acetylene cylinders are equipped with an 8 to 9 mm gas collector hole in the middle.
• a catheter pipe the size of said hole is inserted through the elastic dust obstruction, and the pressurized water is slowly allowed to reach the other end ofthe cylinder through the pipe.
• the water has a wetting and lubricating effect and it will pack the edge between the cylinder and the material, and the pressure will push the material straight into the elastic dust shield.
• the cylinder walls are left moist such that no dust will rise into the ambient air during later phases either.
• the mass removed by the inventive method is left moist, this being of relevance for lates phases.
• the removed asbestos-containing mass in a bag is then taken to asbestos dissolution either directly or via intermediate storage.
• the asbestos is then dissolved in hydrochloric acid in the manner described above, whereby the temperature during the treatment is kept at a value not allowing the plastic or other material used to melt yet, such that said material is available for possible reuse for the same purpose.
• the invention can also be applied to the treatment of asbestos-containing waste from buildings.
• the taking down in buildings can be performed with water, as explained above for acetylene cylinders, but preferably, a high-pressure water jet is used which functions as a shearing and tearing medium. All dust is then moist and will settle easily. According to the method, dry dust is not generated at all.
• Detached asbestos-containing pieces can be removed from the site of dismantling by using either a dry suction machine or a wet suction machine to forward the pieces directly into an acid bath.
• the ventilation air at the building demolition site can be sucked through an acid washer before it is let out.
• the mediod according to the invention for taking down and treating asbestos waste from a building comprises using water or an aqueous solution as the medium for taking down and the detached waste can be brought to an acid treatment directly by suction.
• the asbestos can be pre-wetted by means of the water used for the taking down, which greatly enhances its dissolution in hydrochloric acid.
• the asbestos can be fully and completely dissolved in the hydrochloric acid solution.
• the dissolution of the asbestos will neutralize the hydrochloric acid solution, and the neutralized solution which mainly consists of a solution of CaCl 2 and MgC can be used as anti-icing salt.
• the silicon dioxide fluff and fibres separated from the salt solution by filtering can advantageously be used for reinforcing ⁇ he matrix of concrete.
• the salt solution can also be used for, e.g., emptying and washing acetylene cylinders more advantageously than clean additional water.
• the cylinder cut open in the above-explained manner can be forwarded to further use fit for use, and the remaining waste can also be exploited futher.
• the idea is that since the cylinders face scrapping in any case, it is of advantage to start by cutting the cylinder such that it will serve as a blank for a new product. Used gas cylinders can be utilized to obtain various structurally useful products, and it is not profitable to waste good material by scrapping it for melting in the first place.
• Fig. 1 is a microscopic photograph of asbestos waste treated with hydrochloric acid at an early stage of dissolution
• Fig. 2 is a co ⁇ esponding photograph ofthe end result ofthe treatment.
• a 5 g sample was extracted from a gas cylinder having contained acetylene.
• the sample was comprised of asbestos fibres and cement.
• the sample was wetted with a small amount of water whereafter it was suspended into 55 ml of 33 % hydrochloric acid under stirring. The temperature was 60 °C. After a few minutes of stirring, the cement was completely dissolved. The asbestos fibres began to swell into a slimy thick mass which was partly covered by colloidal material. Next, a small amount (approximately 0.5 g) of potassium sulphate was added into the suspension, whereby the swelling ofthe fibres continued and the colloidal phase began to dissolve. In order to accelerate the dissolution, 3 ml of concentrated nitric acid was added. The colloidal phase disappeared and the fibres were bared again. As a result of continued stirring, the fibres began to break and became thinner (Fig. 1 ). After the addition of phosphoric acid (about 2 ml of concentrated acid) and 15 minutes of stirring, the fibres were completely dissolved. This is also clear from Fig. 2 which shows some silicon dioxide fluff.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Environmental & Geological Engineering (AREA)
• Civil Engineering (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (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)
• Processing Of Solid Wastes (AREA)

Applications Claiming Priority (3)

Publications (1)

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ID=8545227

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• 1996
  • 1996-02-01 FI FI960472A patent/FI960472A/fi unknown
• 1997
  • 1997-02-03 AU AU16035/97A patent/AU1603597A/en not_active Abandoned
  • 1997-02-03 EP EP19970902371 patent/EP0968032A1/en not_active Withdrawn
  • 1997-02-03 WO PCT/FI1997/000057 patent/WO1997027902A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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