WO1992010315A1

WO1992010315A1 - Toxic waste disposal

Info

Publication number: WO1992010315A1
Application number: PCT/AU1991/000571
Authority: WO
Inventors: Donald Peter Campbell; Leslie William Booth
Original assignee: Seldco Pty. Limited
Priority date: 1990-12-12
Filing date: 1991-12-11
Publication date: 1992-06-25

Abstract

Method and apparatus for facilitating the disposal of articles including incandescent and vapour discharge lamps capable of liberating toxic or hazardous wastes during disposal. The apparatus includes a housing; comminuting means within the housing to comminute articles entering the housing via an inlet chute; an impeller having a plurality of hammers swingably mounted for radial movement relative to a shaft rotatable about a substantially horizontal axis; water supplying means supplies water to the articles during comminution; coarse separation means receives the water and comminuted articles to effect a primary separation; fine separation means to effect a secondary separation; and means to pass the effluent from the fine separation means to discharge or recycle.

Description

TITLE: TOXIC WASTE DISPOSAL BACKGROUND OF THE INVENTION

The present invention relates to toxic waste disposal. In one particular embodiment the invention relates to an apparatus suitable for the disposal of filament and discharge lamps including incandescent globes, fluorescent tubes, sodium vapour lamps, mercury vapour lamps, quartz halogen lamps and metal halide lamps which may liberate toxic substances and/or hazardous wastes on disposal. Many filament or discharge lamps in wide general use contain or have surface deposits which comprise toxic or hazardous materials. Examples of toxic or hazardous materials which may be found in filament or discharge lamps include mercury, cadmium, strontium, lead, and antimony sodium.

Safe disposal of such articles after use is difficult. The glass lamp envelope easily breaks into sharp-edged fragments capable of inflicting wounds on a person coming into contact with them. The broken articles may also liberate into the atmosphere gases contained therein and expose the coatings to the air and to rain or water sprays so that the gases or coatings may be washed into the soil and eventually enter the ground water systems of towns. A further hazard arises from the explosive or flammable properties of some of these materials, eg. sodium, in the presence of air and moisture.

It has been proposed to dispose of articles of the above kind by a variety of methods. Several proposals including those disclosed in U.S. Patents 3,913,849 (Atanasoff), 4,579,287 (Brown) and 4,655,404 (Deklerow) involve dropping the tube or lamp being disposed of into the path of a rotor spinning rapidly in a horizontal plane about a vertical axis. There is a danger with such devices that smaller globes or large fragments of tubes can pass through the path of the rotor without being broken, particularly if the speed of rotation diminishes for any reason. Moreover, while such units may be small and relatively portable they do not provide for the safe disposal of sodium vapour lamps, for example, which yield materials flammable in moist air when broken.

This latter point is addressed in U.S. Patent 4,607,798 (Odlin) which provides for a vaned drum rotating about a horizontal axis with the lamps being progressively broken by the shearing action of the vanes as they pass close by the edges of walls which project inwardly from the casing. Throughout operation of the machine the lamps are doused by water issuing from a nozzle to quench any igniting sodium.

However metal end caps and other debris can become wedged between the edges of the walls and the vanes of the rotor thereby causing the arrangement to jam.

The known prior art generally requires that the crushed articles are bagged and buried in the ground. The hazards arising from sharp fragments and the liberation of gases and leaching of harmful materials into the environment are not overcome with such methods. Furthermore, the possibility of recycling the glass and plastics and the hazardous materials after removal of the hazardous materials is not addressed by such methods.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide in one embodiment an apparatus for collecting the material of construction of articles separately from toxic or hazardous materials contained in or deposited upon the articles.

It is a further object of the present invention to provide in another embodiment a method whereby the material of construction of articles containing or having surface deposits of toxic or hazardous materials may be collected separately from the said toxic or hazardous materials.

These and other objects will become further apparent from the following description of the invention. The present invention accordingly provides in one embodiment apparatus for separating from the materials of which articles are constructed other materials contained in or deposited upon the articles, said apparatus comprising a housing, means within the housing to comminute the articles, means supplying water to wet the articles while being comminuted, coarse separation means through which the water and comminuted articles are passed, multi-stage fine separation means receiving the effluent from the coarse separation means, and means to pass the effluent from the final stage of the fine separation means to discharge or to recycle. The present invention also provides in another embodiment an apparatus for facilitating the disposal of articles including incandescent and vapour discharge lamps capable of liberating toxic or hazardous wastes during disposal, said apparatus including: a housing; comminuting means within said housing to comminute articles entering said housing via an inlet chute, said comminuting means comprising an impeller having a plurality of hammers swingably mounted for radial movement relative to a shaft rotatable about a substantially horizontal' axis; water supplying means for supplying water to said articles during comminution; coarse separation means into which the water and said comminuted articles are passed to effect a primary separation thereof; fine separation means for effecting a secondary separation comprising removal of toxic and hazardous materials from the discharge from said primary separation; and means to pass the effluent from the fine separation means to discharge or to recycle.

The coarse and fine separation means are preferably both housed within a substantially sealed chamber. The chamber may be kept at a negative pressure so that gases liberated by the comminuting means are drawn into the chamber and inadvertent discharge of gases via the inlet chute is minimised. A fan may be provided for extracting vapours from the substantially sealed chamber. The coarse separation means preferably comprises a removable skip mounted within a trough immediately below the comminuting means. The water supplying means is preferably adapted to deliver a curtain of water into the chute sufficient to deter the escape of any gaseous materials liberated through comminution. The water supplying means may include a pair of shower means, one adapted to supply a jet of water directly onto the articles during comminution and the other to deliver a curtain of water into the inlet end of the chute.

Preferably a curtain of water falls from the comminuting means into the skip so that liberated gases are effectively drawn through the curtain of water toward the fan. In this way a significant proportion of the gases may be taken into solution and it has been found that the remaining gases may be suitable for discharge to the atmosphere via a flue connected to the fan outlet. The hammers may each be in the form of a chain link. Preferably each link is of a generally triangular shape mounted via an apex of the triangle so that a base thereof forms a broadened end remote from the shaft. Preferably each link, whether triangular or of other shape includes a cross-member. The cross-member may help to retain the chain link in the preferred orientation relative to the shaft.

The coarse separation means is preferably positioned directly beneath the comminuting means so that glass cullet and metal fragments formed by the comminuting means fall directly from the comminuting means into the skip. A pump may be provided to draw discharge liquid from the trough and pass the effluent to the fine separation means.

The fine separation means may comprise a multi-stage filtering system having a plurality of filters arranged in series. There are preferably at least four filters in the series. The filters may include an initial solids filter, an activated carbon filter, at least one ion exchange resin type filter, and preferably cation and/or anion exchange resin filters.

According to a further embodiment of the present invention there is provided a method of separating from articles toxic or hazardous materials contained in or deposited upon the articles, comprising the steps of comminuting the articles by comminuting means in contact with water in an enclosed housing, subjecting the comminuted articles and water to a primary coarse separation process whereby the toxic or hazardous materials and the water pass to subsequent processing while the coarser particles of the comminuted articles are retained, then subjecting the effluent from the coarse separation process to a secondary multi-stage fine separation process whereby toxic and hazardous materials are retained while the effluent from the final stage of the fine separation means passes to discharge or is recycled.

BRIEF DESCRIPTION OF THE DRAWINGS To further assist in the understanding of the present invention, particularly preferred embodiments of the invention will now be described in relation to the drawings.

In the drawings:

Figure 1 is a partly cut-away perspective view of an apparatus according to one preferred embodiment of the invention;

Figure 2 is a cross-sectional view of the apparatus of Figure 1;

Figure 3 is a cross-sectional view of the apparatus of Figure 1 along the line 3-3 indicated in Figure 2; and

Figure 4 is a cross-sectional plan view of the apparatus of Figure 1 along the line 4-4 indicated in Figure 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The preferred embodiment of the apparatus 1 provided by the present invention includes a housing 2 containing the components of the apparatus. Housing 2 includes an inlet chute 3 for receiving toxic or hazardous articles to be treated by apparatus 1. The inlet chute 3 is preferably of a length which substantially exceeds that of any tubes to be disposed of. A length of from 1-3 metres and preferably about 2 metres is particularly preferred.

The inlet end 4 of the chute 3 is sealable via a flap 5 which can be opened when lamps are to be inserted into the apparatus. The flap 5 may accordingly serve as an inlet door.

The inlet to chute 3 may also include a brush inlet 34 adapted to allow smothered entry of globes or tubes to the chute. Globes or tubes may be pushed through the brush inlet 34 while the inlet resists any shards being thrown out of the inlet during comminution.

The discharge end of the chute 3 is in direct communication with the comminuting means 6. The chute 3 may be substantially square or rectangular in cross section, as shown in the drawings. However, other profiles are also envisaged in the scope of the present invention.

The chute 3 is preferably an inclined chute as shown in the drawings. The inclined chute 3 may be conveniently oriented at an angle to the vertical to facilitate loading and passage of articles down the chute under the influence of gravity.

The means for supplying water to articles being comminuted may be in the form of shower means 7. The shower means 7 shown comprises a rose 8. However, other forms of shower means, including a spray jet, preferably a fan type spray jet may also be used in accordance with the present invention. The rose 8 may be situated within the inlet chute 3. The rose 8 is preferably adapted to provide a water spray into the inlet chute 3. The rose 8 may be supplied from mains water, recycled water or other convenient source.

Preferably the rose 8 is adapted to deliver a curtain of water into chute 3 sufficient to deter the escape of any gaseous materials liberated during comminution.

The means for supplying water to articles being comminuted preferably also includes spray means directing a jet of water onto articles being comminuted. The spray means may be a spray jet preferably a fan type spray jet (7A) directing a jet of water onto comminuting means 6. The fan type spray jet 7A may be positioned within inlet chute 3.

Most preferably at least a pair of spray means is provided one (7) in the vicinity of the inlet to chute 3 and the other 7A directed at comminuting means 6.

The apparatus 1 includes means within housing 2 to comminute articles entering via the inlet chute 3. The comminuting means 6 may be in the form of an impeller 9. The impeller 9 may be mounted transversely of inlet chute 3. Impeller 9 may extend across the discharge of the inlet chute 3 so that articles being treated by the apparatus 1 can only leave the chute 3 via the comminuting means 6.

The impeller 9 may comprise a shaft 10 extending across the outlet of the chute 3. The shaft 10 may carry a plurality of hammers 11 for impacting articles passing down the inlet chute 3.

Preferably each hammer 11 is swingably mounted so as to allow at least a limited freedom for movement radially relative to said shaft 10. Such movement facilitates avoidance of jamming the impeller 9.

The shaft 10 may be journalled for rotation about a substantially horizontal axis whereby to cause rotation of hammers 11 whereby to impact articles passed down said chute 3. The preferred direction of rotation of impeller 9 is indicated by the arrows in Figure 2.

An electric motor 12 may be provided to rotate said shaft 10 directly or indirectly, eg. via a pulley 13 and belt 14 as shown in the drawings or by another form of drive train. Preferably the shaft 10 rotates in use at not less than 500 r.p.m. and most preferably at about 1000 r.p.m. The motor 12 is preferably mounted within housing 2 as shown in the drawings.

Preferably a plurality of hammers 11 extends across the chute opening. Most preferably three or four sets of hammers 11 extend across the chute opening as best seen in Figure 3. Each set of hammers 11 may include a mounting member 15. The mounting member 15 may be fixedly mounted on said shaft 10. The mounting member 15 may include one or more eyes or other components each adapted for carrying a hammer 11. Each mounting member 15 preferably carries at least a pair of hammers 11. The hammers 11 may be radially disposed about the shaft 10 in a balanced manner.

Each hammer 11 may be in the form of a fin or a link swingably mounted to a mounting member 15. In one particularly preferred arrangement each hammer 11 comprises a chain link. Chain links having a cross member 16 as best seen in Figure 3 are particularly preferred. Preferably a chain link used as a hammer 11 has a broadened end 18 remote from the mounting member and hence remote from shaft 10 as shown in Figure 3. Hammers 11 of a generally ^•triangular shape mounted via an apex 17 so that a base forms a broadened end 18 are particularly preferred for use in accordance with the present invention.

Substantially solid hammers (not shown) in the form of a plate or fin, hingedly mounted on a rotatable shaft are also envisaged within the scope of the present invention.

The minimum separation between adjacent hammers 11 is preferably not more than 30 mm and most preferably about 20 mm. The discharge end of the inlet chute 3 preferably terminates in a substantially horizontal cutting edge 19. Cutting edge 19 preferably extends substantially across the discharge end of inlet chute 3. The hammers 11 may be mounted whereby to provide a minimal clearance of not more than about 30 mm and most preferably between 5 and 20 mm from the cutting edge 19 during rotation.

The construction and arrangement and the direction of rotation of the shaft (as indicated by the arrows in Figure 3) is preferably such that articles sliding down an inclined chute are comminuted by a downward action of the hammers 11 impacting on the article whereby to crush the article between the hammer 11 and the cutting edge 19.

If an article such as a metal end cap cannot be crushed by hammer 11 the swingable mounting of hammer 11 allows hammer 11 to swing radially relative to shaft 10. Such radial movement of hammer 11 may effectively increase the clearance between broadened end 18 and cutting edge 19 to allow the article to fall into skip 21 without becoming jammed between broadened end 18 and cutting edge 19.

Comminuted articles may fall under the influence of gravity from the comminuting means 6. The coarse separation means 20 may be positioned immediately beneath the comminuting means 6. With this arrangement the glass cullet and metal fragments formed by the comminuting means 6 may fall directly into the coarse separation means 20. The coarse separation means 20 provided according to the present invention may comprise a skip 21 mounted within a trough 22. The skip 21 may include a handle (not shown) to facilitate removal from the trough 22.

The skip 21 may include water permeable sections, eg. mesh inserts 23, whereby liquid effluent may drain from the skip 21 as it is removed from the trough 22. The construction and arrangement of the permeable sections 23 is preferably such as to allow a free flow of water while retaining a majority of solid fragments formed by the comminuting means 6. The exact dimensions, fineness and arrangement of the mesh or other permeable sections may be varied as desired. The fineness of comminution is one factor which may be considered in designing a preferred permeable section. The permeable sections 23 are preferably arranged about three sides of a substantially square skip 21. The sections preferably extend adjacent the base of the skip 21 whereby little liquid effluent need be retained within the skip 21 after draining.

The contents of the skip 21 after drainage of liquid effluent into the trough 22 may be disposed of in land fill or other known disposal means since the solid materials are effectively non-toxic after treatment. In a preferred alternative the glass cullet and metal fragments retained in the skip 21 may be recycled.

The trough 22 may be mounted within a substantially sealed chamber 24 inside the housing 2. The trough 22 may be mounted on rollers 25 or other means by which the trough

22 can be easily removed from the housing 2 to facilitate removal and emptying of the skip 21.

Preferably the trough 22 and the skip 21 contained therein are positioned behind a lockable door 26 so that access to the skip 21 is restricted to authorised service personnel.

Micro-switches or other sensors (not shown) may be provided whereby to prevent operation of the apparatus unless the trough 22 and/or skip 21 are in the operating position and the door 26 closed whereby to substantially seal the chamber 24.

A fluid sensor (not shown) may be provided to sense the level of fluid within the trough 22. The fluid sensor may be adapted and arranged whereby to ensure the solid material caught in the skip 21 remains below the water level.

The water level is raised in the trough 22 by fresh water from the rose 8 passing down the chute 3, a curtain of water continually falls into the trough 22. To retain the desired level a pump 27 may be provided to continually draw discharge liquid from the coarse separation means 20 and pass it to the fine separation means 28.

The pump 27 may comprise the means to pass the effluent from the coarse separation means 20 to the fine separation means 28 and thereby to pass the effluent from the fine separation means 28 to discharge or to recycle. Preferably the coarse separation means 20 and the fine separation means 28 are both housed within the substantially sealed chamber 24. The substantially sealed chamber 24 may be kept at a negative pressure whereby gases liberated by the comminuting means 6 are drawn into the chamber 24 and inadvertent discharge via the inlet chute 3 may be minimised.

A fan 29 may be provided for extracting vapours from the substantially sealed chamber 24. In the preferred construction and arrangement described and shown in the drawings a curtain of water falls from the comminuting means 6 into the skip 21 whereby liberated gases are effectively drawn through the curtain of water toward the fan 29. A significant proportion of the gases may thereby be taken into solution. It has been found that the remaining gases may be suitable for discharge to the atmosphere via a flue connected to the fan outlet.

The fine separation means 28 may also be mounted within the housing 2 and preferably within the substantially sealed chamber 24 therein. Access to the fine separation 28 means may be provided for maintenance purposes via lockable door 30. Micro switches or other control means (not shown) may be provided to prevent operation of the apparatus during servicing or whenever the fine separation means 28 is otherwise inoperative.

The fine separation means 28 preferably comprises a multi-stage filtering system. The multi-stage fine separation means may have a plurality of filters 31 arranged in series. Electrical fluid sensors (not shown) may be provided to control the flow of discharge from the coarse separation means 20 to the fine separation means 28. The pump 27 provided as the means of passing effluent preferably is a corrosive resistant chemical pump.

The filters 31 of the multi-stage fine separation means preferably comprise an initial solids filter (preferably about 100 microns), an activated carbon filter and at least one and preferably two ion exchange resin type filters of the anionic and/or cationic type.

It has been found that the effluent from the preferred four stage filtration system 28 is substantially free of toxic or hazardous materials and suitable for discharge via conventional sewerage outlets via piping 32.

An apparatus provided according to the present invention may also include further control monitors including an hour meter, a filtration warning light and other fail-safe mechanisms to reduce the likelihood of unsafe operation of the apparatus. A visual indication or warning from the monitors and/or sensors included in apparatus according to the invention may be transmitted via control panel 33. Control panel 33 may also include key button and/or other control means for controlling operation of the apparatus.

In one other practical arrangement of apparatus according to the present invention (not shown) an enclosed housing of substantially rectangular cross-section is provided, having a flue to dissipate any gases released during processing, and a loading door. An impeller carrying a plurality of hammers extends across the housing below the loading door. The impeller is rotated either manually by a handle or most preferably by a motor. The handle may be located at least partially outside the housing to facilitate access to the handle by an operator. The motor is preferably located within the housing. A manual or electrical safety switch is provided which prevents rotation of the handle or the motor if the loading door is open.

A downwardly directed jet may be provided above the impeller to direct a spray of water over the impeller, and any articles being processed.

A trough is provided below the rollers to receive water and crushed articles, and a skip comprising a sieve having a mesh size of approximately 3 mm is included in one wall of the sump. A pump conveys the effluent passing through the sieve to a multi-pack filter having a fine mesh, and may convey the effluent from the filter to the jet for recycling.

Use of this apparatus illustrates the method according to the present invention. The articles, in this specific example fluorescent light tubes, are loaded into the housing through the loading chute. The machine is started, to initiate the water spray. The impeller is rotated, with the result that the hammers on the impeller comminute the tubes which then fall into the skip. During this operation, the internal coating on the tubes is continually exposed to the water. If sodium contacts water under such conditions where it is continually doused no appreciable heat is developed. The skip is removed from the trough and emptied periodically, it being possible to separate the glass from the metal and forward them to manufacturers for re-use. The particles retained on the filter may contain valuable metals which may be recovered.

While it has been convenient to describe the invention herein in relation to particularly preferred embodiments, it is to be appreciated that other constructions and arrangements are also considered as falling within the scope of the invention. Various modifications, alterations, variations and/or additions to the constructions and arrangements described herein are also considered as falling within the scope and ambit of the present invention. For example the apparatus provided by the present invention may also be advantageously applied to the disposal of canisters such as Ventolin inhalation canisters, other aerosols and the like.

Claims

1. Apparatus for separating from the materials of which articles are constructed other materials contained in or deposited upon the articles, said apparatus comprising a housing, means within the housing to comminute the articles, means supplying water to wet the articles while being comminuted, coarse separation means through which the water and comminuted articles are passed, multi-stage fine separation means receiving the effluent from the coarse separation means, and means to pass the effluent from the final stage of the fine separation means to discharge or to recycle.

2. Apparatus according to claim 1 wherein the means supplying water comprises a downwardly directed jet located above the comminuting means.

3. Apparatus according to claim 1 or claim 2 wherein the means to comminute the articles comprises an impeller having a plurality of hammers swingably mounted for radial movement relative to a shaft rotatable about a substantially horizontal axis.

4. Apparatus for facilitating the disposal of articles including incandescent and vapour discharge lamps capable of liberating toxic or hazardous wastes during disposal, said apparatus including: a housing; comminuting means within said housing to comminute articles entering said housing via an inlet chute, said comminuting means comprising an impeller having a plurality of hammers swingably mounted for radial movement relative to a shaft rotatable about a substantially horizontal axis; water supplying means for supplying water to said articles during comminution; coarse separation means into which the water and said comminuted articles are passed to effect a primary separation thereof; fine separation means for effecting a secondary separation comprising removal of toxic and hazardous materials from the discharge from said primary separation; and means to pass the effluent from the fine separation means to discharge or to recycle.

5. An apparatus according to claim 4 wherein the water supplying means is adapted to deliver a curtain of water into said chute sufficient to deter the escape of any gaseous materials liberated through comminution.

6. Apparatus according to claim 5 wherein gases liberated by said comminuting means are drawn through a curtain of water toward a fan prior to discharge.

7. Apparatus according to claim 4 wherein each hammer of said plurality of hammers is in the form of a chain link.

8. Apparatus according to claim 7 wherein each said chain link is of a generally triangular shape mounted via an apex whereby a base of said triangle forms a broadened end remove from said shaft.

9. Apparatus according to claim 8 wherein each said hammer includes a cross member.

10. Apparatus according to claim 4 wherein said coarse separation means comprises a removable skip mounted within a trough immediately beneath said comminuting means.

11. Apparatus according to claim 4 wherein said means to pass the effluent from the fine separation means to discharge or to recycle comprises a pump adapted to draw discharge liquid from said coarse separation means and pass said discharge liquid to said fine separation means.

12. Apparatus according to claim 4 wherein said fine separation means comprises a multi-stage filtering system having a plurality of filters arranged in series.

13. Apparatus according to claim 12 wherein said multi¬ stage filtering system includes an initial solids filter, an activated carbon filter and at least one ion exchange resin type filter.

14. A method of separating from articles toxic or hazardous materials contained in or deposited upon the articles, comprising the steps of comminuting the articles by comminuting means in contact with water in an enclosed housing, subjecting the comminuted articles and water to a primary coarse separation process whereby the toxic or hazardous materials and the water pass to subsequent processing while the coarser particles of the comminuted articles are retained, then subjecting the effluent from the coarse separation process to a secondary multi-stage fine separation process whereby toxic and hazardous materials are retained while the effluent from the final stage of the fine separation means passes to discharge or is recycled.