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
• • 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

Definitions

• the present invention relates to a process for treating waste containing asbestos, coming from a site generating such waste, comprising a reaction by attacking said waste with a basic solution until a reactive product is obtained. ⁇ substantially without asbestos fibers.
• the most important treatment centers carry out a) a coating in hydraulic binders and a landfill of the product obtained, or b) an incineration by vitrification at very high temperature.
• WO-A-93/18867 describes a process in which the waste is first of all very finely ground in the presence of at least one substance releasing OH ions " in the water, so as to form an aqueous suspension This suspension is optionally then transferred to an autoclave and treated at high temperature and pressure.
• This process has the disadvantage of a very fine prior grinding step, which requires a very powerful, and therefore fixed, installation. It therefore does not solve the problems inherent in the transport and storage of waste, and it appears to be very costly, and nothing is provided with regard to the vapors and liquid effluents which are released during the process and which in turn risk being pollute the environment.
• WO-A-94/08661 describes a treatment method as indicated at the beginning.
• the only purpose of this process is to produce waste which can be discharged into a depot without the risks inherent in asbestos.
• the only installation described for carrying out this treatment is a large, fixed treatment center, which therefore provides no solution to the problems of transport and storage of waste containing asbestos.
• the waste undergoes energy-intensive compaction before being introduced into the treatment chamber.
• the object of the present invention is to provide a method and an installation which avoid the abovementioned drawbacks and which allow treatment of the waste on the site generating such waste.
• waste generating site should be understood to mean not only a building in which all the elements containing asbestos are dismantled, but also, for example, a refuse deposit where sachets containing asbestos have been previously accumulated. It is therefore desirable that the installation is small and transportable.
• the invention further aims to avoid any risk of pollution between the generator site and the reactor which will treat the waste, that is to say the risk of putting the waste in bags and transporting it. these sachets to a remote processing center.
• the bagging of construction debris is difficult and very often causes the puncturing of bags, which then allows the asbestos to spread into the atmosphere outside the site.
• the invention also aims to prevent as much as possible any outflow of product involved in the treatment, insofar as it still contains asbestos fibers.
• the products resulting from the treatment will be advantageously either recycled or suitable for upgrading.
• the invention finally aims to avoid any crushing, crushing or compacting prior to entry into the reactor and therefore an introduction into it, without sorting, asbestos-laden substrates.
• the transfer takes place in a removable, closed container, and the method further comprises, during or after the transfer, an external washing of the container with a washing liquid.
• a washing liquid This eliminates the asbestos dust which may have settled on the container during its presence in the waste generating site and therefore does not contaminate the place, close to the site, where the basic attack will have location.
• the washing water of the container is recycled in the formation of basic attack solution which avoids any pollution of the environment at the outlet of the closed container outside the waste generating site.
• the removable container used for the above transfer is also the reactor in which the attack reaction takes place. There is therefore in this case no risk of pollution by asbestos during the transfer from one container to another, the waste without sorting is directly introduced into the reactor at the generator site itself.
• the attack reaction is carried out with the basic attack solution at a temperature of the order of 175 to 190 ° C and under a pressure of about 8 to 10 kg / cm 2 .
• the attack comprises
• the solid phase treated has a volume reduced by 70% compared to the volume of waste used in the first attack.
• the second reactor used can then subject this solid phase to a high temperature, sufficient to make the asbestos fibers disappear, without necessarily having to reach in this second reactor, an excessively high pressure. It is thus possible to increase the yield, by drastically reducing the cost of the removable reactors.
• FIG. 4 represents a schematic view, partially in section, of a part of the installation according to the invention on a platform transportable on a trailer.
• FIG. 5 represents a schematic view, partially in section, of another part of the installation according to the invention on another portable platform on trailer.
• FIG. 6 schematically represents, in combination with FIGS. 1 and 3, an alternative embodiment of a treatment installation according to the invention.
• FIGS. 1 to 3 The installation illustrated in FIGS. 1 to 3 comprises a reactor 1 in the form of an autoclave which can be sealed in a sealed manner by a cover, for example a folding cover 2.
• This reactor is designed to be able to withstand internal pressures up to 10 kg / cm 2 . It can be moved here on a trolley 3 provided with casters 4.
• This assembly is dimensioned so as to be able to enter buildings, and therefore to be able to pass through doors and enter an elevator. This makes it possible to fill the reactor 1 with waste dismantled in the building, containing asbestos fibers, without prior sorting or grinding. Once the reactor is filled at the waste generating site itself, and therefore without handling bags, the reactor is taken out of the building where the waste is dismantled.
• a watering station 5 (FIG. 1) which is provided with a watering ramp.
• the harvested washing water is sent to a collecting tank 9, via an outlet pipe 10, fitted with a pump 11.
• the tank 9 is, in the illustrated embodiment, itself mounted so that it can be moved on wheels.
• the reactor 1 has been transferred from the carriage 3 to a support 12 capable of tilting around a shaft 13.
• a quick coupling 14 the output shaft of a rotary motor 15 is coupled to an agitator installed in a manner known at the bottom of the reactor.
• a motor not shown, makes it possible to rotate the shaft 13 on its axis and to tilt the reactor. All these measures allow appropriate agitation of the reactor contents during the attack.
• valve 18 allows entry of rinsing water into the reactor from line 19 and / or entry of basic attack solution from the conduit 20.
• Electric heating elements 21 are, in the illustrated embodiment, provided inside the reactor 1, and they are connected to a current source when the reactor is in place on the support 12.
• the attack with the aqueous basic solution can therefore take place in the reactor 1, without possible exit of asbestos fibers to the outside.
• the basic etching solution may for example be an aqueous solution of OH " ion generating agent, such as alkaline or alkaline earth bases, in particular 25 M NaOH in flakes, obtained for example by dissolving in 0.5 part by volume of water of 1 part by volume of such NaOH flakes.
• the attack preferably takes place at a temperature of 175 to 190 ° C. and under a pressure of 8 to 10 kg / cm 2 , for a period 20 to 30 minutes, advantageously with slow stirring, possibly intermittently. After this attack, there is substantially no more asbestos fibers in the reaction product which has a pasty consistency.
• This reaction product is removed from the reactor 1 via the lower pipe 17, after opening the corresponding valve, and it is brought to a running centrifuge 22. This transfer can be followed by an internal rinsing of the reactor by supplying rinsing water from the pipe 19.
• fresh or rinsing water can also be supplied by a water inlet conduit 23.
• the centrifuge makes it possible to separate in the pasty product a liquid phase and a solid precipitate.
• the liquid phase consisting mainly of water and base of attack is recovered at the bottom of the centrifuge to be recycled by a recycling conduit 24.
• the solid precipitate is sent through the outlet 25 in a tank 26 from which a revalorization of this precipitate can take place.
• a ferrate precipitate complex iron hydroxide
• the precipitates will, for example, be mixed in a cement-based composition, or introduced as adjuvants in refractory materials.
• Reactor 1 at the time of its closure on the generator site, contains, in addition, waste intro ⁇ quized with air heavily loaded with dust and therefore with asbestos fibers. During the attack, these suspended particles are washed and attacked in the same way as solid waste, and the asbestos fibers which were in suspension are therefore also destroyed.
• the upper conduit 16 is again opened, after having closed the channels of the multiple valve 18 leading to the conduits 19 and 20.
• a third channel is then open which communicates with a gas pipe 27 provided with a vacuum pump 28.
• the gaseous medium present in the reactor 1 is then sucked into the pipe 28.
• the path to line 27 is in turn closed, and communication between line 16 and reactor 1 can be closed.
• the cover 2 of the reactor 1 can then be opened without any danger of pollution of the environment.
• Debris that has been introduced with the waste asbestos on the generating site for example bricks, pieces of wood, etc., can then be discharged by tilting the reactor, and possibly by scraping the interior. This debris, completely devoid of asbestos fibers, can then be transported to a depot or another destination.
• the installation comprises a solution preparation tank 29, capable of withstanding a pressure of 10 kg / cm 2 and capable of being heated for example by a heating jacket 30 in which a thermal fluid circulates, including oil.
• the thermal fluid enters at 31 into the jacket 30 and exits at 32.
• the caustic soda flakes are fed from above at 33 in the tank 29, from a silo 34 and passing through a conveyor screw 35.
• Fresh or rinsing water can be provided in the tank 29 via the inlet pipe 36.
• An outlet pipe 37 of the basic attack solution makes it possible to take the latter from the bottom of the tank 29, using a pump 38.
• This outlet pipe 37 is in communication with the conduit 20 previously mentioned (see FIG. 2) by a valve 39 which is open when the reactor 1 is to be supplied with basic attack solution.
• the valve 39 is closed, the basic attack solution is recycled to the top of the tank 29 by a bypass 40, using a static mixer 41.
• the basic solution is brought to the desired concentration, at a temperature close to boiling, for example 120 ° C.
• the installation also advantageously comprises a tank equalization 42 of the basic attack solution.
• This tank is preferably capable of withstanding a pressure of 5 kg / cm 2 , and it is capable of being weakly heated, for example by a heating jacket 43 in which a thermal fluid, in particular oil, circulates. .
• the thermal fluid enters at 44 in the jacket 43 and leaves there at 45.
• the caustic soda flakes are fed from above at 46 in the tank 42, starting from the silo 34 and passing through a conveyor screw 47.
• Fresh water or rinsing water can be introduced into the tank 42 through the inlet pipe 48.
• An outlet pipe 49 of the basic solution of equalization makes it possible to take the latter from the bottom of the tank 42, using a pump 50.
• This outlet duct 49 is in communication with a supply duct 51, by a valve 52.
• This supply duct 51 makes it possible to introduce at the top of the preparation tank 29 a basic equalization solution and thus obtain a basic attack solution of uniform composition.
• the valve 52 is closed, the basic equalization solution is recycled to the top of the tank 42 by a bypass 53, using a static mixer 54.
• the liquid phase separated in the centrifuge is brought through the conduit 24 (see FIG. 2), which makes it possible to recover an important part of the basic attack solution which has already been used.
• the conduit 27, through which the gaseous medium of the reactor 1 leaves after the attack also opens out at the top of the equalization tank 42.
• the collecting tank 9 (see FIG. 1) can also be placed in communication with the tank 42, via line 55, for introducing there the water for washing the outside of the reactor 1. It is also possible, according to another embodiment, for the water for the inside rinsing of the reactor to be directly recycled into recycling conduit 24 without passing through the centrifuge. In this medium formed by liquids and gases from various sources, the base of attack is dissolved at low temperature until reaching the saturation threshold.
• the tanks 29 and 42 of FIG. 3 are supported on the plate 56. Next to these tanks is a current thermal fluid heating device with a thermal fluid tank 57 and a boiler 58.
• FIG 5 there is shown a battery of reactors 1 supported on a plate 64 transportable by trailer.
• the reactors are introduced into a heated enclosure 59, the upper part of which can be opened for the introduction or the extraction of the reactor 1.
• This operation is carried out using a device lifting device known per se 60.
• the heated enclosure 59 is supported on two shaft ends 65 and 66 coaxial so as to be able to rotate about their axis. Agitation of 40 to 50 revolutions per minute is for example favorable.
• the left reactor in FIG. 5 is supplied by a removable container in the form of a tank 61, whose upper wall 62 can be opened for the introduction of waste on the generating site.
• the bottom of this tank 61 provided transportable and movable between the generator site and the transportable treatment unit according to the invention, is formed of a hopper 63 closable by a drawer, not shown.
• the upper opening of the reactor is then closed by a corresponding drawer cover. When the two drawers are open, the waste from the tank 61 can flow into the reactor 1, so that it cannot come into contact with the surrounding medium.
• the centrifuge 22 is installed.
• the two trays 56 and 64 can be installed side by side and to allow communication between the different containers by the conduits mentioned above.
• FIG. 6 an improved variant embodiment of the installation according to the invention is illustrated, where the reactor 1 formed from an autoclave at high pressure of the installation according to Figures 1 to 3 is replaced by two successive reactors: 1) a removable reactor, for example in the form of a small autoclave capable of operating under extremely moderate pressure and 2 °) a fixed reactor 1 ".
• Autoclaves corresponding to the requirements of the removable reactor are those commonly used in chemical laboratories, and they are readily available on the market at moderate cost. These autoclaves have the additional advantage to be able to be provided much lighter and less resistant to pressure, due to the low pressure used.
• the asbestos-containing waste is introduced into the reactor 1a as in the reactor 1 in FIG. 1 and the latter is advantageously washed in the same way at the outlet of the waste generating site. It is then connected to an upper conduit 16 * which makes it possible to put it in communication with the preparation tank 29 of the basic attack solution.
• treatment of waste in reactor 1 • is provided with the basic solution attack at a temperature of 160 to 175 ° C, advantageously 170 ° C, for 15 minutes.
• reaction product is then transferred via a line 17 'to a first centrifuge 22' where the liquid phase is separated from the solid phase.
• the liquid phase is recycled through line 24 'to the preparation tank 29 or to the equalization tank 42.
• the solid phase is in the form of a paste which still contains asbestos fibers, which are completely separated. After analysis, we have already been able to estimate that, in this state, the fibers obtained no longer pose any danger to human health.
• This solid phase now has a volume reduced by 70% compared to that introduced into the reactor. It is brought, via a conduit 25 ′, to reactor 1 ".
• This is a fixed reactor, that is to say one which no longer needs to be moved to the site generating waste, and yet it is of a small volume. Provision may be made for it to be arranged horizontally so as to be able to be driven in rotation about a horizontal axis.
• the basic etching solution is introduced via the 16 “conduit and a temperature above 180 ° C., for example from 190 to 210 ° C., advantageously approximately 200 ° C., is maintained in the reactor 1" by a source of heat 21 ". There is then decomposition and total disappearance of the asbestos fibers, and formation of a pressure inside the reactor. However, as the treated volume of solid phase is reduced, a pressure of 2.5 kg at 10 kg / cm 2 , preferably 2.5 to 5 kg / cm 2 , may be sufficient.
• the reaction product is then transferred to a second centrifuge 22 "through line 17", passing through a cooling device 70.
• the temperature of the product from reactor 1 is dropped below the temperature at which the sodium hydroxide vaporizes, i.e. about 180 ° C.
• this centrifuge there is separation of the liquid phase and the solid phase.
• the liquid phase is recycled through line 24 "to the preparation and / or equalization vats of the basic attack solution and the solid phase is brought through line 25" to tank 26.
• the conduits 16 ′ and 16 " can, like the conduit 16 in FIG. 2, serve as means for recycling the gaseous medium from the respective reactor to the source of basic attack solution.

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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)
• Processing Of Solid Wastes (AREA)
• Fire-Extinguishing Compositions (AREA)

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• 1996
  • 1996-06-10 JP JP50242597A patent/JP3776935B2/ja not_active Expired - Fee Related
  • 1996-06-10 EP EP96915921A patent/EP0846016B1/de not_active Expired - Lifetime
  • 1996-06-10 PT PT96915921T patent/PT846016E/pt unknown
  • 1996-06-10 AT AT96915921T patent/ATE188134T1/de active
  • 1996-06-10 AU AU58886/96A patent/AU704269B2/en not_active Ceased
  • 1996-06-10 PL PL96324011A patent/PL182770B1/pl not_active IP Right Cessation
  • 1996-06-10 ES ES96915921T patent/ES2142064T3/es not_active Expired - Lifetime
  • 1996-06-10 WO PCT/BE1996/000056 patent/WO1997000099A1/fr not_active Ceased
  • 1996-06-10 DK DK96915921T patent/DK0846016T3/da active
  • 1996-06-10 NZ NZ308981A patent/NZ308981A/xx not_active IP Right Cessation
  • 1996-06-10 IL IL12261396A patent/IL122613A/xx not_active IP Right Cessation
  • 1996-06-10 DE DE69605927T patent/DE69605927T2/de not_active Expired - Lifetime
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  • 1996-06-10 CA CA2225523A patent/CA2225523C/fr not_active Expired - Fee Related
  • 1996-06-10 HU HU9901933A patent/HU225596B1/hu not_active IP Right Cessation
  • 1996-06-10 CZ CZ19974034A patent/CZ290478B6/cs not_active IP Right Cessation
• 2000
  • 2000-02-10 GR GR20000400330T patent/GR3032632T3/el unknown
  • 2000-03-01 US US09/516,235 patent/US6391271B1/en not_active Expired - Lifetime

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