CA1170215A

CA1170215A - Concrete wash plant

Info

Publication number: CA1170215A
Application number: CA000388906A
Authority: CA
Inventors: Frederick S. Johnson
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-10-28
Filing date: 1981-10-28
Publication date: 1984-07-03

Abstract

ABSTRACT
A separator for use in separating particles of different sizes in a liquid mixture such as the contents dumped from a mobile mixer at the time of a clean out. The separator includes a chute formed by bottom panels and a pair of side panels joined to the bottom panels along side edges thereof.
An end wall is provided at one end and a loading zone is provided in the chute adjacent the end wall. A screen is provided between the loading end and a stratification zone which is spaced from the loading end. A lifting device is provided for raising the loading end from a loading position to a raised position in which a mixture dumped into the loading end flows toward the stratification zone, the coarser particles being separated by the screen. Unlike known devices used in the ready mixed concrete industry, no pumps, conveyors or other components having moving parts come into contact with the concrete wastes.

Description

The present invention relates to a separator andmore particularly to a method and a~paratus for use in washing out mobile concrete mixers.
Frequently mobile concrete mixers returning from a delivery have a left-over quantity of mixed concrete to dump. Occasionall~ a mixer is overloaded and it becomes necessary to dump part of a load before the mixer leaves for a delivery. At the end of a day, the mixer must be cleaned, and considerable partially set-up concrete may be adhered to the inside of the mixer and particularly around the mixing blades. Disposing of such waste concrete can be bothersome and expensive. It is of course a concern when such wastes are dumped or find their way into rivers, streams, gravel pits and other places, where environmental problems are likely to `develop.
When washing out the mixers, it is frequentl~
found that water alone is not sufficient to remove the partially set-up concrete from the blades. When coarser aggregate was used in a significant percentage of the concrete, it became a practice to add this coarser aggregate :
to the mixer during washout. This ~ added to the disposal problem and attempts were made to recIaim the aggregate because of its cost.

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Some read~ mix concrete companies have built washout pits and have re~ycIed some of the water from the settling ponds formed by the pits by using slurry pumps.
Such pits might be periodlcally cleaned out by using a backhoe or the like, but such a process is an extremely messy operatlon.

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:. . : , ' :,- ' : - : ' 1'7~ ~15 Some machines have been developed for use in the mixer wash process. These machines include a chain conveyor or an auger to remove the solids from a pit or tank. Chains or screws can encounter difficulties if concrete is dumped when they are not operating due to mechanical or electrical failure or to an operator error. If the conve~ors are run continuously at even slow speeds good settling out is not accomplished. In addition, water pumps used in recycling the water are exposed to rather sever conditions.
It is an object of the present invention to provide a separator which can withstand the conditions produced by the dumping of the washout mixture of the mixer and will also be useful in disposing of unused concrete. The separator of the present invention does not have mechanisms, such as conveyors and pumps,directly exposed to the mixture.
- According to one aspect of the invention, there is provided a separator including a chute member having first and second bottom panels extending in an end-to-end fashion at an obtuse angle so as to form a joint line at the abutting ends, side walls joined to the bottom panels along side edges thereof and forming a separation zone therebetween, and an end wall extending between the side walls at an end ~of the first bottom panel remote from the joint llne. A loading zone is formed ~etween the side walls adjacent the end wall,and screen means extend across the chute between the side walls and provide a sifting zone between the loading zone and a~stratification :, zone of the chute in the area of the joint line. Means mounts the chute for pivoting motion about an axis along the joint line between first and second positions. The first bottom :. :

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' ' panel is horizontally disposed in the first position and is raised to an inclined angle in the second position so that a mixture deposited in the loading zone may flow by gravity through the sifting zone towards the stratification zone.
Another aspect of the invention relates to a method of cleaning out mobile concrete mixers and includes the steps of dumping a predetermined quantity of oversize rock and water via a hopper into a mixer, rotating the mixer at a high speed, ~ and discharging the water, rock and dislodged concrete mixture from the mixer into a loading end of a separator chute, the chute being movable between a loading position and a separating position, and then raising the chute from its loading position to the separating position so that the discharged mixture slides by way of gravity towards a stratification zone in the chute. The rock is entrapped in a first screen sifter in the chute and the rock may then be transferred back through the hopper and into the next mixer.
According to yet another aspect of the present invention,there is provided an apparatus for mobile concrete mixer clean out, the apparatus having hopper means for feedlng a supply of securing rocks to a mixer to be cleaned, and a tiltable separator chute having a loadlng end ~or receiving a mixture of rocks, water and concrete ingredients dumped from a mixer. The chute has a stratification zone spaced from the loading end. Means is provided for ralsing the loading end from a lowered position to a raised separating position above the stratification zone.

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- ~-~ 3-'"' , ' , ~.~7(3~5 Screen means is located in the chute for entrapping the scouring rock in the mixture and permitting the remainder of the mixture to flow by gravity from the loading end toward the stratification zone. The chute has means for returning the entrapped rocks to the mixer to be cleaned.
In the accompanying drawings, which show one embodiment of the invention:
Figure 1 is a front elevational view of a tower structure forming part of the washing out apparatus of the present invention and showing a portionof a chute in chain dotted lines;
Figure 2 is a side elevational view of the tower structure of Figure l;
~ igures 3 and 4 are like side elevational views of the complete apparatus, showing the chute in a raised position and in a lowered position, respectively;
Figure 5 is a view similar to Figures 3 and 4, but showing the chute in a clean out position;
Figure 6 is a perspective view of the chute in its raised position;
Figure 7 is a plane view of the chute; and -Figure 8 is an enlarged detailed view of a flow control valve means used in the chute~
Referring first to Figures 3 and 4, the reference numbers 10 and 11 denote a tower structure and a chute member, respectively, and as will be described in more detail below, the chute member is mounted to plVO t in a plane paralleI to a back side of the tower. ~he tower structure includes four ', _ - 4 -, ,:

~ ~7~ 5 corner legs 12 and a top beam configuration ].4 which is spaced sufficiently high above the ground to permit a mobile mixer to be backed under a hop~er means 13 carried by the beam configuration. An operator control panel 15 is mounted adjacent the tower structure. At the back side of the tower a wall 16 is provided which has a window 17 e~uipped with a door 18. The door 18 is mounted on a pivot pin 20, and a piston and cylinder type motor 21 is attached at one end to the wall, a piston rod 22 thereof being attached to a tail portion 23 of the door 18. Upon contraction of the motor 21 the door swings from a window closing position to a window open position as denoted in chain dotted lines. The window 17 is positioned to be immediately above a loading zone 24 of the chute member ..
11 when the chute is in a lowered loading position as indicated in Figure 4.
. The chute member 1 has a bottom formed by two portions or panels 33,34 connected at a joint line 37 along abutting end edges. The bottom panels 33,34 which are end-to-end relationships are disposed at an obtuse angle relative to 20: each other. Side walls 35,36 which have V-shaped bottom edges, are connected to side edges of the bottom panels. The loading zone 24 is provided adjacent the end of the bottom panel 33 opposite the joint line 37. The top edges of the side walls 35,36 at the loading end of the chute members are substantially : parallel to the bottom panel so that they are horizontal when the chute member 11 is in a loading position, as shown in Figure 4, this end in effect providing an extension 38 of the otherwise triangular side elevation shape of the chute.

: -5-, Z~L5 The chute member ll may be mounted on a concrete pad or other base means 40 and is adapted to pivot about an axis of pivot which is coextensive with the joint line 37.
A pair of large piston and::cylinder type motors 42,42 are provided at opposite sides of the chute member, the cylinder ends of the motors being pivotally connected to anchor means 43 in the base means 40 intermediate the axis 41 and the load end of the chute member~ the piston rods of the motors being pivotally connected to the side walls 35,36 above the anchor means. When the piston rods of the motors 42,42 are fully retracted, the chute member is held in its loading position in which the bottom panel 33 is horizontally disposed on top of the base means 40 (Figure 4). When the piston rods are partially ex-tending by the motors 42,42 being simultaneously activatedj the chute member is raised to a separating position as shown in Figure 3. In the event the piston rods are fully -- -extended, the chute member is tilted still further to a clean out position as shown in Figure 5. .
The space between the side walls 35,36 generally forms a separating zone 45 including downstream from the loading zone 24, a sifting zone 46 and a settling-out or stratification zone 47. At the extreme end of the end~extension 38 there is provided an end wall 50. Water storage means is provided immediately inside of end wall 50,. the water storage means consisting of a truck water storage tank 51 separated from a rinse water storage tank 52 by a wall;53, whlch, like end wall 50 extends between side walls 35,36. Another wall 54 separates the ; rinse water tank 52 from the loading zone 24. A top wall 55 completes the enclosure of the truck water storage tank 51 - while the rinse water storage tank 52 may be opened top.

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'' " ' ' ' The wall 54 does not extend, however, completely to the bottom panel 33 so as to provide a bottom gap 30. A conduit or pipe 56 has an open end 59 downstream from the sifting :zone and horizontally disposed when the chute member is in the loading position shown in Figure ~. The pipe 56 has its other open end 57 disposed in the truck water storage tan]c 51 and is provided wikh an opening 58.
Between the sifting zone 46 and the stratification ~ zone 47 a gate 60 is pi.vo-tally hung between the side walls 35,36. When the chute member is in its lowered loading position as shown in Figure 4, the gate is perpendlcular to the bottom panel 33 to prevent flow of the solids from the stratification zone towards the loading zone. When the chute member is raised to its separating position as shown in Figure 3, the gate swings relative to the bottom so as to .remain in a vertical position where it permits flow from the loading zone into the stratification zone.
The sifting zone which in effect commences in the loading zone in~.ludes two screen members 61 and 62. The screen 61 is coarse to permit passage of all normal constituents of concrete but to entrap large scouring rocks~ The screen is inclined towards the wall 35 so that as the chute member is raised to its separatlng position (Flgure 3) the scouring rocks entrapped by the screen 61 roll towards an opening 63 in side wall 35. ~ valve means 70 is provided for controlling the flow through opening 63 and is in the form of large flexible hose 64 which is in communication with the opening 63 and it is normally held in an up position, as is sh~wn in chain-d~tted lmes in Figure ~, ~y way of a rigid member 65 which is connected by pivot means 66 to the side wall 35.~ A piston and cylinder motor 67 is . . .

' s connected between the wall 35 and rigid member 65, and when actuated to extend the piston rod thereof, the rigid member 65 is pivoted down to release the flexible hose to swing to a downwardly inclined position. In the downwardly inclined position the outer end of the hose is below opening 63 and over hopper 28 so as to permit the scouring rocks entrapped by screen 61 to flow into hopper 28.
Screen 62 is much finer than screen 61 and is inclined `~ towards the opposite side wall 36. The screen is sized to entrap aggregate from the concrete water mixture flowing through the screen 61. The entrapped aggregate is directed towards an opening 71 in side wall 36 and the flow therefrom may be controlled with a valve means, such as 70 described above.
The truck water storage tank 51 is provided with an opening near the bottom thereof, and flow of water from this tank is controlled also by a valve means of the type described above. The water from tank 51 is directed through hopper 27 by way of the valve means when the chute member is in its raised position shown in Figure 3.
A probe 73 is located in the stratification zone 47 and may be in the form of a rod which is normally free to swing to a vertical position. When a build-up developes in the stratification zone it will eventually~impede the free swing of the probe. A sha~t 74 extends to the outside o~ the chute and may have a microswitch arrangement (not shown) associated therewith for detectlng the lack of swing of the probe due to the build-up inside of the chute. A signal thus communicated to the control panel 17 could be used to produce an alarm indicative of a need for clean out~oX the stratification zone.

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~'7(~ 5 The apparatus may be provided with a self-contained hydraulic system including a pump which is driven by an electric motor (not shown), and the operating steps of the apparatus may be individually controlled by an operator, who may be the mixer driver. Alternatively, the apparatus may include, within the control panel 15, the necessary relay switches and timers so that the mixer driver need do little more than select a particular operation.
i An automated apparatus might include, for example, means for sensing the entry of a truck under the hopper 13 for starting the hydraulic pump. If the mixer driver wishes to wash out his mixer he can select either water or the water and scouring rock combination by activating the appropriate switch or switches. The motor of the~valve means associated wlth opening 72 would then be activated to permit the flow of water from tank 51, the water being directed by hopper means 13 into the mixer.
If scouring rock is also to be supplied, the motor of the valve means 70 associated with the opening 71 is activated to release the entrapped scouring rocks thorugh the hopper 13.
After the water or the water and rocks have been added to the mixer, the mixer is rotated at a high speed so as to free the concrete and form a mixture of water, rock and .
concrete wastes. In the meantlme, the motors of the valves 70 are activated to close openings 71 and 72, and the motors 42,42 are activated to lower the chute to its loading position.
The motor 21 is then activated to raise the door 18 and expose the window 17 above the loading end of the chute. The delivery chute of th~ mixer may then be directed through the window and the mixture from the mixer dumped into the loading end of chute member 11. The truck may then leave, and this action may .~

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')z~s be detected to activate motor 21 for closing the door 18.
On the lower of the chute prior to the dumping of the mixture from the mixer, water starts to drain through the pipe 56 to fill tanks 51 and 52. This filling is complete by the time the mixer leaves the site, and after the door 18 is closed, the chute raises to its raised separating position. The dumped mixture t:hus flows by gravity away from the loading end. The scouring rocks are entrapped by screen 61 and roll towards wall 35.
The remainder of the mixture passes to the screen 62 which entraps the concrete aggregate, and the screen 62 directs the aggregate towards the wall 36. The remaining fine particles, water and cement wastes travel under the then open gate 60 to the stratification zone. As the chute reaches its raised position and the mixture flows away from the loading end, the water stored in the tank 52 flows out through gap 30 and washes through the loading and sifting zones so as to clean the screens, the scouring rocks and the collected aggregate. The control system may then activate the motor controlling the valve means for the opening 70 for discharging the collected aggregate. The aggregate is thus reclaimed and may be returned to the mixing plant for reuse.
The chute remains in the raised position and settling out takes place in the stratification zone. When the chute is lowered to its loading position on arrival of the next mixer, the water above the settled out materlals, which has a level indicated by 79, flows back towards the loading end. The gate 60 is not tight fitting so that the water is able to quick1y assume the same level 80, when the chute is in the loading position, throughout the length of chute deflned by bottom panel 33O
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.. ~ ' -1~'7()~15 In the event the mixer operater only requires water for a wash out, the scouring rocks remain in the screen 61 throught the cycle of lowering and raising of the chute.
If a ~ixer is returned with left-over mixed concrete, water may be added to it in the mixer and the mixture dumped ~s described above. The aggre~ate from the mixture is thus reclaimed.
When an overload condition exists in the mixer prior to delivery, the chute may b~ operated through a cycle which does not involve the transfer of water or rocks to the mixer.
The chute is lowered and the door 18 is opened so that a quantity of the concrete may be dumped directly into the loading zone. When t~e chute is raised the aggregate is separated by screen 62 as the concrete flows with the water present at the loading zone to the stratification zone. The collected aggregate is then further washed by the flow of water from the tank 52 which continues to flow for some time aft r the remai~der.ofthe mixture and water has reached the stratification zone. The clean aggregate may then be released for reuse. ~ ~
When the concrete wastes reach a built-up condition, the pro~e will become held in a single position as the chute is tilted back and forth between loadlng and separating positions.
A signal is then given, such as a light at the control panel, at which time a service man may actuate cylinders 42 to move ~the chute to the position shown in Figure 5. This is preferably done at a very 510w speed to enable the water to slowly flow from the chute and leave the bullt-up~ materials undisturbed The chute may then be cleaned with a machineJ such as a front-~ end loader, and the waste material hauled away. The chute is 1. ~
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then re-turned to the separating position and refilled with water.
The chute is then moved to the loading position to fill the storage tanks through pipe 56, and returned to the separating position ~t this point the chute is ready for normal use.
From the above, it is apparent that aggregate is readily reclaimed in an apparatus which in effect has no moving parts, such as pump impellors or conveyors exposed to the concrete wastes, and that the messy conditions which develope around existing separator pits would not exist with the disclosed apparatus.
Although only a single embodiment of the apparatus has been illustrated, various alternative embodiments which would fall within the spirit of the invention as defined in the appending clalms,would be obvious to those ~k~lled ln Lhe art.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A separator for a liquid-solid mixture, the separator comprising a chute member including first and second bottom panels extending at an obtuse angle from a joint line at abutting ends of said panels side walls joined to the bottom panels along side edges thereof to form a separation zone therebetween, an end wall extending between said side walls at an end of the first bottom panel opposite the end at the joint line, a loading zone being formed between the side walls adjacent said end wall, screen means extending across said chute between said side walls and providing a sifting zone between said loading zone and a stratification zone of the chute in the area of said joint line, means mounting said chute for pivoting motion about an axis along said joint line between first and second positions, and means for moving said chute between said first and second positions, said first bottom panel being horizontally disposed in said first position and being raised to an inclined angle in said second position whereby a mixture deposited in said loading zone may flow by gravity through said sifting zone towards said stratification zone.

2. A separator according to claim 1, wherein said chute is pivotable to a third clean out position in which said first bottom panel is moved to a steeper inclination and said second panel is horizontally disposed.

3. A separator as defined in claim 1, wherein said screen means includes a one screen member provided with openings to permit passage of the mixture except particles larger than a predetermined size, said screen slanting towards one of said side walls in a direction away from said loading zone whereby said mixture is sifted through said screen member when the chute is moved to said second position and the larger particles are directed towards said one side wall.

4. A separator as defined in claim 3, wherein an opening is provided in said one side wall for discharge of the collected particles separated by said screen member.

5. A separator as defined in claim 4, and including valve means for controlling discharge through said opening.

6. A separator as defined in claim 3! wherein said screen means includes another screen member of coarser mesh than said one screen member and located upstream from said one screen member, said another screen member being inclined towards the other said side walls for directing objects of a size greater than said particles separated by the first screen member towards said other side wall.

7. A separator as defined in claim 6, wherein said other side wall is provided with an opening for discharging said objects collected by said another screen member, and further comprising valve means for controlling flow of said objects through said opening in said other wall.

8. A separator as defined in claim 1, wherein the stratification zone in said chute provides a settling area for fine material, and further comprising a gate between said screen means and said stratification zone, said gate being mounted to move to an open position as said chute pivots to said second position and to move to a closed position as said chute moves to the first position whereby flow of said material back towards said loading zone is prevented by said gate as said chute is moved towards said first position.

9. A separator as defined in claim l, and including means forming a liquid storage tank adjacent said loading zone and liquid return means for permitting flow of liquid from said stratification zone to said tank when said chute is in said first position.

10. A separator as defined in claim 9, and further comprising outlet means in said tank, and valve means for permitting flow from said storage tank when said chute is moved to said second position.

11. A separator as defined in claim l or 8, and including a rinse storage tank adjacent said loading zone, means permitting flow of liquid from said intermediate zone to said rinse storage tank when said chute is in said first position, and outlet means in said rinse storage tank for permitting the escape of liquid from said tank and through said screen means when said chute is moved to said second position.

12. A method of cleaning out mobile concrete mixers comprising:
dumping a predetermined quantity of oversize rock and water into a mixer, rotating said mixer at a high speed, discharging the water, rock and dislodged concrete mixture from said mixer into a loading end of a separator chute, the chute being movable between a loading position and a separating position, raising said chute from the loading position to the separating position whereby the discharge mixture slides by way of gravity towards a stratification zone in said chute, entrapping said rock in a first screen sifter of said chute, and holding the entrapped rock for dumping into the next mixer,

13. The method of claim 12 and including the further steps of returning the chute to the loading position for collecting discharge from said next mixer, transferring water from the stratification zone to a storage tank, raising the chute to the separating position after receiving the dumped mixture from the next mixtures, and holding the water in said storage tank for return to said mixer.

14. The method of claim 12 or 13 and including the further steps of:
entrapping concrete aggregate of said mixture by way of a second screen sifter as said mixture slides from said first screen sifter towards said stratification zone, and discharging the entrapped concrete aggregrate from said chute as reclaimed aggregrate.

15. The method of claim 12 and including the further steps of:
returning the chute to the loading position for collecting discharge from said next mixer, transferring water from the stratification zone to a rinse water tank, raising the chute to the separating position after receiving the dumped mixture from the next mixture, and permitting water from the rinse water tank to discharge and rinse through said loading end and towards said stratification zone as said chute approaches said separating position.

16. The method of claim 12, 13 or 15 and further comprising:
periodically moving said chute to a clean out position for removing fine particles and cement settled out in said stratification zone.

17. An apparatus for cleaning out mobile concrete mixers comprising:
a hopper means for transferring a supply of scouring rocks to a mixer to be cleaned, a tiltable separator chute having a loading end for receiving a mixture of rooks, water and concrete ingredients from the mixer, said chute further having a stratification zone spaced from said loading end, means for raising said loading end from a lowered loading position to a raised separating position above said stratification zone, screen means for entrapping said scouring rock in said mixture and permitting the remainder of said mixture to flow by gravity from said loading end toward said stratification zone, and means for returning the entrapped rocks to said hopper.

18. An apparatus as defined in claim 17, wherein said chute includes a bottom panel means and a pair of side walls joined to the bottom panel means along opposite side edges thereof and forming a separating zone therebetween, and an end wall extending between said side walls at the loading end of said chute, said bottom panel means including a first portion disposed in a substantially horizontal position when said chute is in the loading position and in an inclined position, sloping from said loading end to said stratification zone, when said chute is in said separating position.

19. An apparatus as defined in claim 18, wherein said bottom panel means includes a second portion arranged in end-to-end fashion and at an obtuse angle relative to said first portion, said panel portions being connected at a joint line forming an axis of pivot for said chute.

20. An apparatus as defined in claim 19, wherein said chute is titlable about said axis to a third clean out position, said second portion being horizontally disposed in said third position.

21. An apparatus as defined in claim 19, wherein said hopper means includes a tower structure, said hopper being mounted on said tower and under which a mixer may be driven, said hopper having means for permitting flow of said rock by way of gravity to said mixer.

22. An apparatus as defined in claim 21, wherein said chute is mounted adjacent said tower, said loading end of said chute in said loading position being disposed adjacent to a side wall of said tower, said wall includes a window above said loading end of said chute for passage of said mixture to the loading end of said chute.

23. An apparatus as defined in claim 23, and including door means movable between a window closing position and a retracted position, and means for moving said door to the window closing position before said chute leaves said loading position.

24. An apparatus as defined in claim 22 or 23, wherein said chute is mounted for tilting in a plane parallel to said tower wall, the rock return means being disposed to permit rocks to flow by gravity from said chute to said hopper when said chute is raised to the separating position.

25. An apparatus as defined in claim 18, wherein means are provided adjacent said end wall defining a water storage tank and a conduit for transferring water from said stratification zone when said hopper is in said loading position.

26. An apparatus as defined in claim 25 and including valve means for permitting flow of water from said tank to said hopper means when said chute is in the raised position.

27. An apparatus as defined in claim 25, wherein said tank includes an opening for permitting water to discharge into said loading end and flow towards said stratification zone when said chute is raised to said separating position and thereby providing a chute rinsing action.

28. An apparatus according to claim 18, wherein said screen means includes a first course screen for entrapping said rocks in said loading end, and a second screen intermediate said first screen and said stratification zone, said second screen being finer than said first screen and sized to entrap concrete aggregate.

29. An apparatus as defined in claim 28 wherein said second screen is inclined to one side wall of said chute for directing collected aggregate towards said one wall, said one side wall being provided with an opening for permitting flow of the collected aggregate from said chute.

30. An apparatus as defined in claim 29, and including valve means for controlling the flow of collected aggregate through said opening.

31. An apparatus as defined in claim 18 and including a gate mounted between said side walls upstream of said stratification zone, said gate being mounted to swing to an open position when said chute is moved to said raised position and thereby to permit the flow of the mixture into said stratification zone and to swing to a closed position when said chute is lowered to said loading position and thereby prevent the flow of settled out material back towards said loading end.

32. An apparatus as defined in claim 31 and including a probe located in said stratification zone for detecting a built up condition of settled out material, and means producing a signal to indicate such condition.