CA2090888A1 - Process for recycling asbestos-containing acetylene gas cylinders - Google Patents
Process for recycling asbestos-containing acetylene gas cylindersInfo
- Publication number
- CA2090888A1 CA2090888A1 CA002090888A CA2090888A CA2090888A1 CA 2090888 A1 CA2090888 A1 CA 2090888A1 CA 002090888 A CA002090888 A CA 002090888A CA 2090888 A CA2090888 A CA 2090888A CA 2090888 A1 CA2090888 A1 CA 2090888A1
- Authority
- CA
- Canada
- Prior art keywords
- gas cylinder
- asbestos
- cylinder
- process according
- acetylene
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 title claims abstract description 45
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims abstract description 25
- 239000010425 asbestos Substances 0.000 title claims abstract description 24
- 229910052895 riebeckite Inorganic materials 0.000 title claims abstract description 24
- 238000004064 recycling Methods 0.000 title description 3
- 239000002253 acid Substances 0.000 claims abstract description 11
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000011737 fluorine Substances 0.000 claims abstract description 10
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 10
- 150000007522 mineralic acids Chemical class 0.000 claims abstract description 9
- 239000000463 material Substances 0.000 claims abstract description 8
- 150000003839 salts Chemical class 0.000 claims abstract description 6
- 238000000354 decomposition reaction Methods 0.000 claims description 35
- 239000003795 chemical substances by application Substances 0.000 claims description 27
- 239000000203 mixture Substances 0.000 claims description 16
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 12
- 238000007789 sealing Methods 0.000 claims description 10
- 238000003860 storage Methods 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 4
- 238000007599 discharging Methods 0.000 claims description 4
- -1 hexafluorosilicic acid Chemical compound 0.000 claims description 4
- 238000001914 filtration Methods 0.000 claims 1
- 238000005201 scrubbing Methods 0.000 claims 1
- 239000011232 storage material Substances 0.000 claims 1
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 abstract description 12
- 239000011159 matrix material Substances 0.000 abstract description 6
- 239000002904 solvent Substances 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 51
- 239000000470 constituent Substances 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000002245 particle Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 229910001868 water Inorganic materials 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 239000000920 calcium hydroxide Substances 0.000 description 2
- 235000011116 calcium hydroxide Nutrition 0.000 description 2
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000008247 solid mixture Substances 0.000 description 2
- 239000007858 starting material Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 1
- 229910017665 NH4HF2 Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
- 238000007084 catalytic combustion reaction Methods 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000011067 equilibration Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 230000010006 flight Effects 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- VBKNTGMWIPUCRF-UHFFFAOYSA-M potassium;fluoride;hydrofluoride Chemical compound F.[F-].[K+] VBKNTGMWIPUCRF-UHFFFAOYSA-M 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- BFXAWOHHDUIALU-UHFFFAOYSA-M sodium;hydron;difluoride Chemical compound F.[F-].[Na+] BFXAWOHHDUIALU-UHFFFAOYSA-M 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 238000009489 vacuum treatment Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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
-
- 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
Landscapes
- Business, Economics & Management (AREA)
- Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Emergency Management (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Processing Of Solid Wastes (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Treating Waste Gases (AREA)
- Fire-Extinguishing Compositions (AREA)
Abstract
Abstract of the Disclosure A process for disposing in an environmentally acceptable manner of acetylene compressed-gas cylinders containing an asbestos-containing support matrix, which serves as support for acetone, which acts as solvent for the acetylene (C2H2), and which are unsuitable for refilling, the method comprising decomposing the asbestos-containing support material using a fluorine-containing inorganic acid or a corresponding salt of such an acid.
Description
8 ~` ~
PROCESS FOR RECYCLING ASBESTOS-CONTAINING
ACETYLENE GAS CYLINDERS
Background of the Invention This invention relates to a process for the conversion of acetylene gas cylinders into recyclable material and to an apparatus particularly suitable for carrying out the process.
Acetylene is used as an intermediate in chemical synthesis and as fuel gas for welding torches. For safe handling, acetylene is stored and transported in special acetylene gas cylinders. The interior of an acetylene gas cylinder is filled with a porous solid composition which ',! contains asbestos. Currently conventional porous solid compositions essentially comprise calcium silicate and asbestos. Starting materials for these porous compositions Lnclude calcium oxide, silicon dioxide, asbestos, water, and optionally fillers. These starting materials are stirrQd to ; form a paste which is introduced into a gas cylinder, and the starting materlals are reacted together at a temperature of approximately 200C. The compositions are then dried at 350 to 400C. The resulting porous compositions have a pore volume of greater then 90%.
Acetone serves as solvent for the acetylene to be compressed. A 40 liter gas cylinder may contain 12.5 kg of acetone and 8.0 kg of acetylene under a total pressure of 19 bar at 20C.
The gas cylinders are indeed refillable in principle, but for safety reasons, the cylinders must at some point be ' ..
PROCESS FOR RECYCLING ASBESTOS-CONTAINING
ACETYLENE GAS CYLINDERS
Background of the Invention This invention relates to a process for the conversion of acetylene gas cylinders into recyclable material and to an apparatus particularly suitable for carrying out the process.
Acetylene is used as an intermediate in chemical synthesis and as fuel gas for welding torches. For safe handling, acetylene is stored and transported in special acetylene gas cylinders. The interior of an acetylene gas cylinder is filled with a porous solid composition which ',! contains asbestos. Currently conventional porous solid compositions essentially comprise calcium silicate and asbestos. Starting materials for these porous compositions Lnclude calcium oxide, silicon dioxide, asbestos, water, and optionally fillers. These starting materials are stirrQd to ; form a paste which is introduced into a gas cylinder, and the starting materlals are reacted together at a temperature of approximately 200C. The compositions are then dried at 350 to 400C. The resulting porous compositions have a pore volume of greater then 90%.
Acetone serves as solvent for the acetylene to be compressed. A 40 liter gas cylinder may contain 12.5 kg of acetone and 8.0 kg of acetylene under a total pressure of 19 bar at 20C.
The gas cylinders are indeed refillable in principle, but for safety reasons, the cylinders must at some point be ' ..
2 ~
withdrawn from circulation. In the past, there was no way to dispose of such cylinders in an environmentally acceptable manner. Because of the asbestos content of the porous support matrix, such cylinders must not be sawn or cut up using a cutting torch, especially since explosive residual quantities of acetone and acetylene may remain in the cylinders.
Summary of the Invention The object of the present invention is to provide an environmentally acceptable process for preparing asbestos-containing acetylene gas cylinders for recycling.
A further object of the invention is to provide an apparatus for introducing a decomposition agent into an acetylene gas cylinder and discharging any resulting exhaust gas.
These and other objects of the invention are achieved by providing a process for converting an acetylene gas cylinder containing an asbestos-containing storage composition into recyclable material, the process comprising decomposing the asbestos-containing storage composition in the acetylene gas cylinder by contacting the asbestos-containing composition with a decomposition agent comprising a fluorine-containing inorganic acid or a salt of a fluorine-containing inorganic acid, and thereafter discharging residues of decomposed asbestos-containing storage composition from the acetylene gas cylinder.
The process according to the invention for the conversion of acetylene gas cylinders having asbestos-containing storage compositions into recyclable materialprovides that the asbestos-containing storage compositions in the acetylene gas cylinder are decomposed using a fluorine-containing inorganic acid or a salt of a fluorine-containing inorganic acid as a decomposition agent, and the decomposed residue is eliminated from the acetylene gas cylinder.
~ he decomposition can be exothermic and can lead to an expansion of the air or gas atmosphere present in the gas cylinder, or reaction gases can be formed. The resulting exhaust gas and/or gas displaced from the cylinder due to the introduction of the decomposition agent is advantageously passed through a particle filter in order to separate any entrained solids, for example asbestos-containing particles of the support matrix. The exhaust gas can additionally be passed through a gas scrubber, in which water-soluble exhaust constituents, for example entrained hydrofluoric acid, can be washed out. To remove organic constituents which may be contained in the exhaust gas, the exhaust gas can be conducted across suitable absorption filters, for example activated charcoal. Alternatively, organic constituents can be burned off catalytically or non-catalytically.
To eliminate organic constituents, particularly acetylene and acetone, from the acetylene gas cylinder, the cylinder can be allowed to stand for a relatively long time after the cylinder valve has been unscrewed and removed prior to carrying out the process according to the invention. Volatile organic constituents then gradually evaporate. Volatile organic constituents may be advantageously pumped away by applying a vacuum. The organic constituents which are pumped off can then be disposed of, for example by catalytic or non-catalytic combustion. Instead of, or in addition to, a vacuum treatment, the organic constituents in the acetylene gas cylinder can be converted into less volatile or less flammable substances, for example by addition of an oxidant such as an hydrogen peroxide solution, or by addition of an agent such as a transition metal halide, which initiates polymerization of acetylene and/or acetone.
Preferred decomposition agents include hydrogen fluoride, hexafluorosilicic acid and tetrafluoroboric acid, preferably in the form of an aqueous solution. Acid-. . ' . .
- : - . ~ :
2 l~ C~ 53 8 reacting alkali metal or ammonium salts of such acids are also suitable, for example NH4HF2, NaHF2 or KHF2. However, other, preferably water-soluble salts of fluorine-containing acids can be used, preferably then in combination with an acid, especially a mineral acid.
The decomposition agent may be introduced into the acetylene gas cylinder in anhydrous form, and water and optionally an acid can then be added. However, preferably an aqueous solution of the decomposition agent is used. The concentration of the decomposition agent in the aqueous solution must be high enough so that an asbestos decomposition reaction is initiated. It is therefore preferable to use an aqueous solution which contains at least 5% by weight of the decomposition agent. The concentration of decomposition agent in the aqueous solution may advantageously be from 5 to 40% by weight. Higher concentrations are possible, but the resulting reaction may then be more vigorous than desired. Hydrofluoric acid is especially suitable as the decomposition agent.
The decomposition in the acetylene gas cylinder is preferably carried out at temperatures between ambient temperature and 85C. If desired, the reaction can be intensified by supplying external heat energy. However, when decomposition agents such as hexafluorosilicic acid, tetrafluoroboric acid or, in particular, hydrofluoric acid are used, an exothermic reaction is observed, and it is not necessary to supply external heat energy in such a case.
The gas cylinder may be cooled if necessary.
To carry out the process the cylinder valve is removed and the decomposition agent is introduced through the resulting opening. The decomposition residue can be discharged from the gas cylinder during or after the decomposition process is carried out, for example by removal using suction or by allowing the decomposition residue to drain out.
.
.
The opening produced by unscrewing and removing the cylinder valve is advantageously sealed with respect to the surroundings, and the decomposition agent is- introduced through a special feed conduit, while any resulting exhaust air or exhaust gas is discharged through an outlet conduit.
Brief Description of the Drawin~s The invention will be described in further detail hereinafter with reference to illustrative preferred embodiments shown in the accompanying drawings in which:
Figs. la and lb are schematic illustrations of alternate apparatus for introducing a decomposition agent into an acetylene gas cylinder; and Fig. 2 is a schematic view of an apparatus for carrying out the process of the invention.
Detailed Description of Preferred Embodiments In accordance with a preferred embodiment, an apparatus specially adapted for introducing the decomposition agent into an acetylene gas cylinder and discharging any resulting exhaust air is used. Two embodiments of such an especially adapted apparatus are reproduced in Figures la and lb, respectively. Each apparatus includes a sealing body 1 which is provided with a thread 2 which is compatible with the thread provided on the acetylene gas cylinder for receiving the cylinder valve (for example: left-handed thread, pitch 14 flights per inch, top diameter 31.3 mm, cone 3:25). The sealing body iB provided with one or more openings 3, 4, which facilitate introduction of the decomposition agent and pressure equilibration or discharge of exhaust gas. The feed conduit 5 is advantageously designed as a tube or pipe which is arranged so as to be movable along the vertical axis of the gas cylinder towards the sealing body. Desirably, the feed conduit is sufficiently long that it can be lowered to the bottom in the interior of the acetylene gas cylinder. The outlet . . ~ . .
.: , ~ ' . ' ' - ~
: :: ' -2 ~
conduit 6 can be designed as a shorter tube or pipe whichprojects into the interior of the acetylene gas cylinder.
The feed conduit and the outlet conduit can be sealed against each other or against the sealing body by a sealing means (not shown). In the embodiment of Fig. la the outlet conduit 6 is disposed centrally within feed conduit 5. In the embodiment of Fig lb the outlet conduit 6 is extended through a separate opening 4 parallel to feed conduit 5.
Means such as a hex head (not shown) may be provided on sealing body 1 in order to facilitate screwing of the sealing body into the thread of the gas cylinder. When such an apparatus is used, the process according to the invention becomes particularly simple.
The process is further described with reference to the use of such an apparatus according to the invention. A 40 liter acetylene cylinder containing 10 kg of porous support matrix was cleaned. The acetylene gas cylinder was initially depressurized. If desired, escaping gases can be burnt off, and volatile constituents can be removed by application of a vacuum. Volatile constituents can also be allowed to escape when the cylinder valve (e.g. DIN no. 477, shape C) is unscrewed.
An apparatus according to the invention is then screwed onto the gas cylinder. As shown in Figure 2, the exhaust gas or outlet conduit 6 is connected via a three-way valve 7 to a particle filter 8 and an exhaust gas scrubber 9, and to a compressed-air source 10. The feed conduit 5 is connected via a three-way valve 11 to a reservoir 12 for the decomposition agent and via the conduit 13 to a receptacle for the decomposed residue. Valve 7 is turned to allow exhaust gas from outlet conduit 6 to pass to the particle filter 8 and the gas scrubbers 9, and the three-way valve 14 is turned to connect reservoir 12 to feed conduit 5. 20%
strength hydrofluoric acid was slowly introduced via a metering device (not shown) into the gas cylinder 15 through the feed conduit 5, which ends adjacent the porous matrix 2~9~g8 16. A suspension of decomposed residue 17 was gradually formed. The feed conduit was slowly lowered. 1.1 kg of HF
in the form of a hyd~ofluoric acid solution containi~g 20%
by weight HF were added per kilogram of porous solid support composition. After complete decomposition of the porous matrix, the three-way valve ll was turned to connect conduit 5 to discharge conduit 13, and the three-way valve 7 was turned to connect conduit 6 to the compressed-gas source 10.
By applying a superatmospheric pressure, the suspension of the decomposed residue was forced through conduits 5 and 13 into the receptacle 14.
If desired, the gas cylinder 15 can be flushed or washed with water, and the wash water can likewise be pumped via conduit 13 into receptacle 14. If necessary, the decomposed residue can be further reacted in receptacle 14 and then neutralized using milk of lime. The acetylene gas cylinder, which has now been freed of asbestos, can likewise be neutralized using milk of lime, dried and then subjected to a safety inspection. Depending on the outcome of this inspection, it is suitable for reuse or it can be disposed of without danger.
The materials with which the decomposition agent comes into contact are advantageously made of hydrogen fluoride-resistant material, for example polytetrafluoroethylene or a suitable metal alloy.
The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Since modifications of the described embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed broadly to include all variations falling within the scope of the appended claims and equivalents thereof.
. .
~' .
' , r ~, .
'' , "' ' "-' ' "' ~ ,".' ' ' ' . .
.,
withdrawn from circulation. In the past, there was no way to dispose of such cylinders in an environmentally acceptable manner. Because of the asbestos content of the porous support matrix, such cylinders must not be sawn or cut up using a cutting torch, especially since explosive residual quantities of acetone and acetylene may remain in the cylinders.
Summary of the Invention The object of the present invention is to provide an environmentally acceptable process for preparing asbestos-containing acetylene gas cylinders for recycling.
A further object of the invention is to provide an apparatus for introducing a decomposition agent into an acetylene gas cylinder and discharging any resulting exhaust gas.
These and other objects of the invention are achieved by providing a process for converting an acetylene gas cylinder containing an asbestos-containing storage composition into recyclable material, the process comprising decomposing the asbestos-containing storage composition in the acetylene gas cylinder by contacting the asbestos-containing composition with a decomposition agent comprising a fluorine-containing inorganic acid or a salt of a fluorine-containing inorganic acid, and thereafter discharging residues of decomposed asbestos-containing storage composition from the acetylene gas cylinder.
The process according to the invention for the conversion of acetylene gas cylinders having asbestos-containing storage compositions into recyclable materialprovides that the asbestos-containing storage compositions in the acetylene gas cylinder are decomposed using a fluorine-containing inorganic acid or a salt of a fluorine-containing inorganic acid as a decomposition agent, and the decomposed residue is eliminated from the acetylene gas cylinder.
~ he decomposition can be exothermic and can lead to an expansion of the air or gas atmosphere present in the gas cylinder, or reaction gases can be formed. The resulting exhaust gas and/or gas displaced from the cylinder due to the introduction of the decomposition agent is advantageously passed through a particle filter in order to separate any entrained solids, for example asbestos-containing particles of the support matrix. The exhaust gas can additionally be passed through a gas scrubber, in which water-soluble exhaust constituents, for example entrained hydrofluoric acid, can be washed out. To remove organic constituents which may be contained in the exhaust gas, the exhaust gas can be conducted across suitable absorption filters, for example activated charcoal. Alternatively, organic constituents can be burned off catalytically or non-catalytically.
To eliminate organic constituents, particularly acetylene and acetone, from the acetylene gas cylinder, the cylinder can be allowed to stand for a relatively long time after the cylinder valve has been unscrewed and removed prior to carrying out the process according to the invention. Volatile organic constituents then gradually evaporate. Volatile organic constituents may be advantageously pumped away by applying a vacuum. The organic constituents which are pumped off can then be disposed of, for example by catalytic or non-catalytic combustion. Instead of, or in addition to, a vacuum treatment, the organic constituents in the acetylene gas cylinder can be converted into less volatile or less flammable substances, for example by addition of an oxidant such as an hydrogen peroxide solution, or by addition of an agent such as a transition metal halide, which initiates polymerization of acetylene and/or acetone.
Preferred decomposition agents include hydrogen fluoride, hexafluorosilicic acid and tetrafluoroboric acid, preferably in the form of an aqueous solution. Acid-. . ' . .
- : - . ~ :
2 l~ C~ 53 8 reacting alkali metal or ammonium salts of such acids are also suitable, for example NH4HF2, NaHF2 or KHF2. However, other, preferably water-soluble salts of fluorine-containing acids can be used, preferably then in combination with an acid, especially a mineral acid.
The decomposition agent may be introduced into the acetylene gas cylinder in anhydrous form, and water and optionally an acid can then be added. However, preferably an aqueous solution of the decomposition agent is used. The concentration of the decomposition agent in the aqueous solution must be high enough so that an asbestos decomposition reaction is initiated. It is therefore preferable to use an aqueous solution which contains at least 5% by weight of the decomposition agent. The concentration of decomposition agent in the aqueous solution may advantageously be from 5 to 40% by weight. Higher concentrations are possible, but the resulting reaction may then be more vigorous than desired. Hydrofluoric acid is especially suitable as the decomposition agent.
The decomposition in the acetylene gas cylinder is preferably carried out at temperatures between ambient temperature and 85C. If desired, the reaction can be intensified by supplying external heat energy. However, when decomposition agents such as hexafluorosilicic acid, tetrafluoroboric acid or, in particular, hydrofluoric acid are used, an exothermic reaction is observed, and it is not necessary to supply external heat energy in such a case.
The gas cylinder may be cooled if necessary.
To carry out the process the cylinder valve is removed and the decomposition agent is introduced through the resulting opening. The decomposition residue can be discharged from the gas cylinder during or after the decomposition process is carried out, for example by removal using suction or by allowing the decomposition residue to drain out.
.
.
The opening produced by unscrewing and removing the cylinder valve is advantageously sealed with respect to the surroundings, and the decomposition agent is- introduced through a special feed conduit, while any resulting exhaust air or exhaust gas is discharged through an outlet conduit.
Brief Description of the Drawin~s The invention will be described in further detail hereinafter with reference to illustrative preferred embodiments shown in the accompanying drawings in which:
Figs. la and lb are schematic illustrations of alternate apparatus for introducing a decomposition agent into an acetylene gas cylinder; and Fig. 2 is a schematic view of an apparatus for carrying out the process of the invention.
Detailed Description of Preferred Embodiments In accordance with a preferred embodiment, an apparatus specially adapted for introducing the decomposition agent into an acetylene gas cylinder and discharging any resulting exhaust air is used. Two embodiments of such an especially adapted apparatus are reproduced in Figures la and lb, respectively. Each apparatus includes a sealing body 1 which is provided with a thread 2 which is compatible with the thread provided on the acetylene gas cylinder for receiving the cylinder valve (for example: left-handed thread, pitch 14 flights per inch, top diameter 31.3 mm, cone 3:25). The sealing body iB provided with one or more openings 3, 4, which facilitate introduction of the decomposition agent and pressure equilibration or discharge of exhaust gas. The feed conduit 5 is advantageously designed as a tube or pipe which is arranged so as to be movable along the vertical axis of the gas cylinder towards the sealing body. Desirably, the feed conduit is sufficiently long that it can be lowered to the bottom in the interior of the acetylene gas cylinder. The outlet . . ~ . .
.: , ~ ' . ' ' - ~
: :: ' -2 ~
conduit 6 can be designed as a shorter tube or pipe whichprojects into the interior of the acetylene gas cylinder.
The feed conduit and the outlet conduit can be sealed against each other or against the sealing body by a sealing means (not shown). In the embodiment of Fig. la the outlet conduit 6 is disposed centrally within feed conduit 5. In the embodiment of Fig lb the outlet conduit 6 is extended through a separate opening 4 parallel to feed conduit 5.
Means such as a hex head (not shown) may be provided on sealing body 1 in order to facilitate screwing of the sealing body into the thread of the gas cylinder. When such an apparatus is used, the process according to the invention becomes particularly simple.
The process is further described with reference to the use of such an apparatus according to the invention. A 40 liter acetylene cylinder containing 10 kg of porous support matrix was cleaned. The acetylene gas cylinder was initially depressurized. If desired, escaping gases can be burnt off, and volatile constituents can be removed by application of a vacuum. Volatile constituents can also be allowed to escape when the cylinder valve (e.g. DIN no. 477, shape C) is unscrewed.
An apparatus according to the invention is then screwed onto the gas cylinder. As shown in Figure 2, the exhaust gas or outlet conduit 6 is connected via a three-way valve 7 to a particle filter 8 and an exhaust gas scrubber 9, and to a compressed-air source 10. The feed conduit 5 is connected via a three-way valve 11 to a reservoir 12 for the decomposition agent and via the conduit 13 to a receptacle for the decomposed residue. Valve 7 is turned to allow exhaust gas from outlet conduit 6 to pass to the particle filter 8 and the gas scrubbers 9, and the three-way valve 14 is turned to connect reservoir 12 to feed conduit 5. 20%
strength hydrofluoric acid was slowly introduced via a metering device (not shown) into the gas cylinder 15 through the feed conduit 5, which ends adjacent the porous matrix 2~9~g8 16. A suspension of decomposed residue 17 was gradually formed. The feed conduit was slowly lowered. 1.1 kg of HF
in the form of a hyd~ofluoric acid solution containi~g 20%
by weight HF were added per kilogram of porous solid support composition. After complete decomposition of the porous matrix, the three-way valve ll was turned to connect conduit 5 to discharge conduit 13, and the three-way valve 7 was turned to connect conduit 6 to the compressed-gas source 10.
By applying a superatmospheric pressure, the suspension of the decomposed residue was forced through conduits 5 and 13 into the receptacle 14.
If desired, the gas cylinder 15 can be flushed or washed with water, and the wash water can likewise be pumped via conduit 13 into receptacle 14. If necessary, the decomposed residue can be further reacted in receptacle 14 and then neutralized using milk of lime. The acetylene gas cylinder, which has now been freed of asbestos, can likewise be neutralized using milk of lime, dried and then subjected to a safety inspection. Depending on the outcome of this inspection, it is suitable for reuse or it can be disposed of without danger.
The materials with which the decomposition agent comes into contact are advantageously made of hydrogen fluoride-resistant material, for example polytetrafluoroethylene or a suitable metal alloy.
The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Since modifications of the described embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed broadly to include all variations falling within the scope of the appended claims and equivalents thereof.
. .
~' .
' , r ~, .
'' , "' ' "-' ' "' ~ ,".' ' ' ' . .
.,
Claims (11)
1. A process for converting an acetylene gas cylinder containing an asbestos-containing storage composition into recyclable material, said process comprising decomposing the asbestos-containing storage composition in the acetylene gas cylinder by contacting said asbestos-containing composition with a decomposition agent comprising a fluorine-containing inorganic acid or a salt of a fluorine-containing inorganic acid, and discharging residues of decomposed asbestos-containing storage material from the acetylene gas cylinder.
2. A process according to claim 1, further comprising scrubbing exhaust gas from the gas cylinder.
3. A process according to Claim 1, further comprising filtering exhaust gas from the gas cylinder.
4. A process according to claim 3, wherein said exhaust gas is filtered through an activated charcoal filter.
5. A process according to claim 1, further comprising exhausting volatile materials from said acetylene gas cylinder prior to contacting said asbestos-containing storage composition in said cylinder with said decomposition agent.
6. A process according to Claim 1, further comprising converting any organic residues in the gas cylinder into non-volatile products prior to contacting said asbestos-containing storage composition in said cylinder with said decomposition agent.
7. A process according to claim 1, wherein said decomposition agent consists of at least one acid selected from the group consisting of hydrofluoric acid, hexafluorosilicic acid and tetrafluoroboric acid.
8. A process according to Claim 7, wherein said decomposition agent is an aqueous solution containing from 5 to 40% by weight of said fluorine-containing inorganic acid or salt of a fluorine-containing inorganic acid.
9. A process according to Claim 1, wherein the decomposition agent is introduced into the acetylene gas cylinder via a vertically movable feed conduit parallel to a vertical axis of said gas cylinder; any exhaust gas is discharged from the gas cylinder via an outlet conduit; and, after completion of decomposition, said feed conduit is lowered vertically downwardly toward the bottom of said gas cylinder, and pressure is applied to said outlet conduit to force decompositions products out of said gas cylinder through a discharge conduit connected to said lowered feed conduit.
10. An apparatus for converting an acetylene gas cylinder having a valve attachment thread for receiving a cylinder valve and an containing asbestos-containing storage composition into recyclable material, said apparatus comprising a sealing body which seals the interior of the acetylene gas cylinder from the surrounding environment via a sealing body thread which is compatible with the valve attachment thread of the acetylene gas cylinder, said sealing body further comprising a feed conduit for introducing a decomposition agent into the cylinder and an outlet conduit for exhausting gas from the cylinder.
11. An apparatus according to Claim 10, further comprising a vertically movable discharge conduit attached to said feed conduit.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DEP4206647.6 | 1992-03-03 | ||
DE4206647A DE4206647A1 (en) | 1992-03-03 | 1992-03-03 | RECYCLING ASBESTIC ACETYLENE GAS BOTTLES |
Publications (1)
Publication Number | Publication Date |
---|---|
CA2090888A1 true CA2090888A1 (en) | 1993-09-04 |
Family
ID=6453104
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA002090888A Abandoned CA2090888A1 (en) | 1992-03-03 | 1993-03-03 | Process for recycling asbestos-containing acetylene gas cylinders |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0559051B1 (en) |
JP (1) | JPH0615251A (en) |
AT (1) | ATE176597T1 (en) |
CA (1) | CA2090888A1 (en) |
DE (2) | DE4206647A1 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19510636C1 (en) * | 1995-03-23 | 1996-01-04 | Rewiever Gmbh | Device for cleaning acetylene gas bottles |
EP0887088B1 (en) * | 1997-06-27 | 2003-10-01 | Gérard Debailleul | Process and installation for the treatment of asbestos-containing absorbing mass in gas bottles |
WO2008001464A1 (en) * | 2006-06-30 | 2008-01-03 | Onc Co., Ltd. | Method of asbestos degradation and asbestos degradation apparatus |
JP4910755B2 (en) * | 2007-02-21 | 2012-04-04 | 繁 岡田 | Asbestos treatment liquid and asbestos treatment method |
JP4852571B2 (en) * | 2008-06-11 | 2012-01-11 | 国立大学法人宇都宮大学 | Detoxification method and detoxification device for asbestos-containing object |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3708014A (en) * | 1971-06-23 | 1973-01-02 | Phillips Petroleum Co | Hydrochloric acid/hydrofluoric acid treatment to remove asbestos fibers from a well bore |
US4349463A (en) * | 1981-01-19 | 1982-09-14 | Union Carbide Corporation | Acetylene storage vessel |
WO1989010338A1 (en) * | 1988-04-30 | 1989-11-02 | Nippon Steel Chemical Co., Ltd. | Asbestos-treating agent and process for treating asbestos |
-
1992
- 1992-03-03 DE DE4206647A patent/DE4206647A1/en not_active Withdrawn
-
1993
- 1993-02-23 AT AT93102799T patent/ATE176597T1/en active
- 1993-02-23 DE DE59309363T patent/DE59309363D1/en not_active Expired - Fee Related
- 1993-02-23 EP EP93102799A patent/EP0559051B1/en not_active Expired - Lifetime
- 1993-03-02 JP JP5040817A patent/JPH0615251A/en active Pending
- 1993-03-03 CA CA002090888A patent/CA2090888A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
---|---|
DE4206647A1 (en) | 1993-09-09 |
EP0559051A1 (en) | 1993-09-08 |
ATE176597T1 (en) | 1999-02-15 |
DE59309363D1 (en) | 1999-03-25 |
JPH0615251A (en) | 1994-01-25 |
EP0559051B1 (en) | 1999-02-10 |
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