SLURRY RECOVERY AND SEPARATION
The present invention relates to the capture, recovery, and reuse of water from slurries produced during concrete cutting operations.
Concrete cutting requires the continuous use of water during the cutting process to cool and lubricate the rotary cutting disc, however, the production of concrete dust (particles) during the cutting process, after mixing with the water, results in a slurry that until recently has been commonly disposed of into storm water drains or similar. This is not environmentally acceptable with present day standards and the problem is commonly dealt with by utilizing a mobile vacuum collector truck that a concrete cutting contractor would normally hire. The vacuum collector truck provides a convenient means for collecting most of the slurry produced and thereafter transporting same to a suitable disposal site. The problem with the use of such vacuum collector trucks is that they are relatively expensive to hire and also they may not be available when a contractor wishes to actually undertake a concrete cutting job. A second problem with existing concrete cutting processes is that a convenient supply of water is not always available at a particular job site, and even if it is, the large level of water wastage is becoming unacceptable where water supply is itself a limited resource. If a continuous water supply is not available then the contractor needs to carry enough water in a portable reservoir for a reasonable work period before necessarily having to refill their portable reservoir to enable the concrete cutting job to continue. This can take some time making the overall concrete cutting process inefficient.
The objective of the present invention is to provide an arrangement for use with concrete cutting equipment that will enable slurries that are produced to be collected for later proper disposal of the solids or semisolids material, and which will enable water used in the cutting process to be at least partially recycled to enable significant extensions of the period during which concrete cutting can occur without necessarily having to refill a portable water supply of the arrangement.
Accordingly, the present invention provides a vehicle mounted arrangement for supplying flushing liquid (normally water) to concrete processing apparatus when in use and for the collection of slurries containing particle solids
material and said flushing liquid produced by use of said concrete processing apparatus, said arrangement including flushing liquid tank means for retaining a supply of said flushing liquid, delivery means for delivering flushing liquid from said flushing liquid tank means, when used, to a position of use of the concrete processing apparatus, a settling tank means, vacuum creating means for creating vacuum conditions in a first upper region of said settling tank means, slurry retrieval means adapted, in use, to receive slurry from the region of said concrete processing apparatus and to return same to said first region of the settling tank means via a pressure differential along said slurry retrieval means, a flushing liquid flow passage for the supply of said flushing liquid from the settling tank means to said flushing liquid tank means or to the position of use of the concrete processing apparatus, and solids collection means positioned to collect solid or semisolid material settling to a second lower region of said settling tank means and to enable removal of said solid or semisolid material collected by said collection means from said settling tank means.
The concrete processing apparatus is conveniently concrete cutting machines such as saws or the like, but could also include, drilling, grinding and polishing machines, or any combination of same.
Preferred features of the invention may be as defined in claims 2 to 25 inclusive annexed hereto, the subject matter of these claims being included in the disclosure of this specification by this reference thereto.
It will be apparent that by providing slurry retrieval means as defined above, the slurry produced normally in concrete cutting operations is substantially retrieved and not released into the environment. This slurry is returned into a settling tank arrangement where the solids concrete dust and other particles / settle out to a lower region from where they are collected or retrieved to be disposed of in a correct environmentally friendly manner. The cleaner flushing liquid from the settling tank arrangement, after the solids have mostly settled out therefrom, is returned to the flushing liquid tank or tanks, preferably via a filter arrangement, for reuse. Thus it is possible to operate for much longer periods without having to refill the flushing liquid tank or tanks while preventing or minimizing the escape to the environment of most of the solids produced by the process.
One preferred embodiment of this invention will hereafter be described with reference to the accompanying drawings, in which:
Fig 1 is a schematic flow diagram of apparatus according to the present invention; Fig 2 is a schematic side view of apparatus shown in Fig 1 mounted on a load tray of a truck or similar vehicle; and
Fig 3 is a rear view of the settling tank, partially sectioned, as represented schematically in Fig 2.
Referring to Fig 1 , a schematic flow diagram illustrates the principles of operation of an arrangement 10 according to a preferred embodiment of the present invention. The arrangement 10 is generally carried on a load carrying tray 11 of a truck, trailer or similar vehicle. The arrangement includes a flushing liquid (normally water) tank 12, a settling tank 13, a fan or vacuum pump 14 and a drive motor 15 driving the fan or vacuum pump 14. The drive motor 15 may be any suitable self powered motor including suitable internal combustion engines. The flushing liquid tank 12 might be duplicated so as to enable each tank to be selectably usable as described hereafter. The apparatus illustrated diagrammatically includes concrete cutting apparatus 16 including a cutting disc or wheel 17 and located on the ground 18 in a position of use. Flushing liquid is delivered via a delivery passage 19, a flow control valve
20 from the tank 12, and a flexible hose 21 removably connected to the delivery passage 19 or valve 20. The hose 21 includes a nozzle 22 to direct flushing liquid flow as desired to a concrete cutting zone 23. As a result, and as is normal, a slurry of water and concrete particles / dust is produced in the region of the cutting zone 23.
Vacuum conditions are established in an upper region 24 of the settling tank 13 by a passage 25 connecting this region 24 to the fan or vacuum pump 14. A control device 26 allows gas to be drawn from the settling tank 13 but prevents the passage of flushing liquid or solids material along the passage 25. A retrieval passage 27 with a flow control valve 28 is provided connected to the region 24 of the settling tank 13. A flexible hose 29 connects releasably to the retrieval passage 27 (or the valve 28) with a distal end 30 positionable adjacent the cutting zone 23 so that slurry produced at the cutting zone 23 can be collected thereby
and delivered along the hose 29 and retrieval passage 27 to be deposited in the settling tank 13. Conveniently, two retrieval passages 27 might be provided on separate sides of the settling tank 13, each having a flow control valve 28 and each being selectably connectable to a slurry retrieval hose 29. Preferably the vacuum passage 25 is positioned spaced from the slurry retrieval passage or passages 27. Conveniently when two oppositely located slurry retrieval passages 27 are provided, the vacuum passage 25 might be located midway between same. A float sensor 31 may be provided in the tank 13 which provides signals indicative of the height of the liquid level 32 in the tank 13 and to control flows to the tank as required, either by actuating the valve 28 or controlling operation of the fan or vacuum pump 14. The sensor might also control the flow of flushing liquid from the tank 13 if desired. In one possible arrangement liquid flow might be directed from a cleaner liquid zone of the tank 13 directly to the flushing liquid hose 21. An external liquid height indicator device 33 is provided on the outside of the tank 13 but connected inwardly thereof to demonstrate the height of the liquid within the tank 13.
Within the tank 13, the solids material within the flushing liquid (water) tends to settle to the bottom region 34 of the tank where it passes to a butterfly valve 35 controlling a discharge aperture leading to a collector bin 36. Thus the solids material and an acceptably small amount of flushing liquid is collected in the collector bin 36. If need be, when the collector bin 36 is full, it can be removed for proper disposal of its contents at a later time and replaced by a further collector bin so that operation of the arrangement 10 can continue if desired. A seal 37 is provided between the bin 36 and the tank 13. Flushing liquid is desirably returned from a zone of the tank 13 where the liquid is relatively free of solids material via a passage 38, a filter 39 and valve device 40, to the flushing liquid tank (or tanks) 12. Any suitable filter arrangement 39 can be provided to minimize or prevent the flow of solids materials into the tank or tanks 12. A drain 41 and control valve 42 enable the tank or tanks to be flushed from time to time to prevent the build up of solids, that might pass the filter 39. In a possible alternative, a directional valve 70 in line 38 might be positioned to direct liquid flow via line 71 directly into the flushing liquid hose line 21. Such an
arrangement is not continuously sustainable but may be used in some applications.
Referring now to Figs 2 and 3, like features in Fig 1 have been given the same reference numbers in Figs 2 and 3. Fig 2 shows the arrangement 10 supported on the load carrying tray 11 of a truck 43 or similar vehicle. The apparatus may include a lift device 44 such as a mini crane or the like to assist with moving the concrete cutting machine 16 from a truck transport position 45 to a ground use position 46 as illustrated. The collector bins 36 might include ground support wheels 47 and lift handles 48 that might also allow ease of handling by the lift device 44. As best seen in Fig 3, a plurality of bolts 49 secure the valve 35 in place and the bolts 50 secure the collector bin 36 to the tank structure 13. Each of the bins 36 have upper and lower passages 51 , 52, each controlled by a valve 53, 54. The lower passage 52 is generally of greater diameter relative to the upper passage 51 and permits an operator to open the valve 54 to remove some of the collected thick slurry or slurry with a high solids content in the bin 36. This slurry is discharged into a separate container (not shown) for proper disposal. Periodic removal of such collected material from the bin 36 allows the apparatus to be used for much longer periods. At the end of an operation stage, typically at the end of a working day, the bin 36 may be removed with its contents disposed of in a proper manner. The upper passage 51 might have a relatively smaller diameter than the lower passage 52 and is provided if an operator inadvertently allows the bin 36 to fill to an extent where operation of the valve 35 might be obstructed. Should this occur, the passage 51 is connected to a passage 72 leading to the upper region 24 of the settling tank via a removable flow passage or tube 73. In this condition, if the valve 53 is opened, the strong vacuum conditions in the upper region 24 drags at least some of the over filled material in the bin 36 to redeposit same in the settling tank 13. The lower region 34 of the settling tank 13 may include inclined walls 55, 56 leading to the discharge aperture and butterfly valve 35. The interior of the tank 13 preferably includes generally vertical baffles 57 in at least an intermediate height zone 58 of the tank, the baffles 57 including a central longitudinal baffle 59 and three spaced transversely extending baffles 60, 61 and 62. The baffles 60, 61 and 62 may have a zigzag configuration to increase rigidity and strength. The baffle 59 is
longitudinal to the tank 13 but because the tank is transversely disposed on the truck tray 11 , it is transverse to the truck tray 11.
