Introduction

This invention relates to a mobile aggregate scrubbing system, and in particular for washing bulk material such as aggregates, minerals and other materials to a high commercial standard by washing out a high quantity of contaminants contained in the raw feed material.

Background to the Invention

There are existing systems for washing bulk material like aggregates and minerals contaminates. A known system includes a primary vibrating rinsing screen which rinses the material and screens out the 0 to 5mm fines. The 5 to 75mm material is then fed into a washer which has two counter rotating shafts with replaceable paddles which lift and abrade the material against itself to break down the soluble clays which are washed out with the upward flowing water which flow over a weir leaving the washed stone. The material is then discharged from the washer onto a vibrating rinsing screen to polish and rinse off any residual contamination. In another conventional system a feed conveyor delivers bulk materials into a scrubbing barrel at a high level above the ground (5 to 6m). Large quantities of water are added along with the feed material. The scrubbing barrel has lifting paddles that lift the material through the injected water which emulsify the 0 to 63um contaminants. This system relies on the attrition of the material dropping from the lifting paddles to break down the clay particles. The scrubbed material is then fed onto a vibrating rinsing screen which will screen the material into different sizes. These existing systems are essentially static systems, are relatively expensive and require expensive preparation civil work to be installed prior to delivery of the system.

The present invention is directed towards providing an improved bulk material washing system which is efficient and flexible in operation. Summary of the Invention

According to the invention, there is provided a mobile aggregate scrubbing system, comprising: an input chamber for reception of bulk material, a plurality of water jets mounted at an inlet of the input chamber, the water jets being operable to break down bulk material in the input chamber, a venturi operable to deliver bulk material from the input chamber to a mixing chamber to further break down the bulk material, a plurality of spaced-apart water jets mounted at an outlet of the mixing chamber, a material transfer pipe extending between the outlet of the mixing chamber and a dilution box, the material transfer pipe being inclined upwardly between the mixing chamber and the dilution box, and the dilution box having a material discharge outlet.

In one embodiment of the invention the waterjets at the outlet of the mixing chamber are directed inwardly and are circumferentially spaced-apart around the outlet of the mixing chamber.

In another embodiment the waterjets at the outlet of the mixing chamber are mounted on a rotating collar which is rotatably mounted at the outlet of the mixing chamber.

In another embodiment the rotating collar is drivably connected to a variable speed electric or hydraulic motor.

In another embodiment operation of the waterjets rotates the collar at the outlet of the mixing chamber. In another embodiment the mixing chamber is cylindrical and has an inlet positioned adjacent but spaced-apart from an outlet of the venturi. In another embodiment the venturi, the mixing chamber and the material transfer pipe have a common axis.

In another embodiment a bore of the mixing chamber has a removable lining of wear resistant material.

In another embodiment a plurality of spaced-apart impact bars are mounted at the inlet of the input chamber and the waterjets are mounted at the inlet to direct infeed bulk material against the impact bars. In another embodiment the material transfer pipe is inclined at an angle in the range of 15° to 30° to the horizontal.

In another embodiment the material transfer pipe is inclined at an angle of 22°. In another embodiment the dilution box has an inner liner of wear resistant material.

In another embodiment the dilution box has an internal wear plate opposite an inlet of the dilution box against which incoming material impacts. In another embodiment a shredder is mounted within the dilution box to break down incoming material.

In another embodiment the shredder comprises a plurality of rotating blades. In another embodiment an outlet of the dilution box cooperates with an associated vibrating rinsing screen to distribute material discharged from the dilution box across a full width of an inlet of the vibrating rinsing screen.

In another embodiment a plurality of water jets are mounted on the dilution box directed towards the inlet of the dilution box. In another embodiment the mixing chamber is rotatable about a longitudinal axis of the mixing chamber.

In another embodiment the transfer pipe is rotatable about a longitudinal axis of the transfer pipe.

In another embodiment the input chamber has a crushing system for crushing material between the venturi and the mixing chamber. In another aspect the invention provides a mobile bulk material processing system incorporating the mobile aggregate scrubbing system.

Brief Description of the Drawings The invention will be more clearly understood by the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 is an eievational view of a mobile aggregate scrubbing system according to the invention;

Fig, 2 is a sectional eievational view of an input chamber portion of the mobile aggregate scrubbing system; Fig. 3 is a sectional plan view of the input chamber portion of the mobile aggregate scrubbing system;

Fig. 4 is an end eievational view of the input chamber of portion of the mobile aggregate scrubbing system;

Fig. 5 is an eievational view of a transfer pipe portion of the mobile aggregate scrubbing system;

Fig. 6 is an end eievational view of the transfer pipe portion of the mobile aggregate scrubbing system; Fig. 7 is a detail sectional plan view of a dilution box portion of the mobile aggregate scrubbing system;

Fig. 8 is an elevational view of the dilution box portion of the mobile aggregate scrubbing system;

Fig. 9 is an elevational view of the mobile aggregate scrubbing system of the invention, shown in use in association with an infeed hopper;

Fig. 10 is a plan view of the mobile aggregate scrubbing system and infeed hopper;

Fig. 11 is an elevational view of a mobile bulk material washing system incorporating the mobile aggregate scrubbing system of the invention;

Fig. 12 is a plan view of the mobile bulk material washing system shown in Fig. 11 ;

Fig. 13 is a sectional elevational view of an input chamber portion of another mobile aggregate scrubbing system according to the invention;

Fig. 14 is a sectional end elevational view of the input chamber portion shown in Fig. 13;

Fig. 15 is a view similar to Fig. 14 showing the input chamber portion in another position of use;

Fig. 16 is a sectional elevational view of an input chamber portion of a further mobile aggregate scrubbing system according to the invention;

Fig. 17 is an end sectional elevational view of the input chamber portion shown in Fig. 16; and

Fig, 18 is a view similar to Fig. 17 showing the input chamber portion in another position of use.

Detailed Description of the Preferred Embodiments

Referring to the drawings, there is illustrated a mobile aggregate scrubbing system according to the invention, indicated generally by the reference numeral 1 . The system 1 has an input chamber 2 for reception of bulk material. A first set of spaced-apart of waterjets 3 mounted at an inlet of the input chamber 2 are operable to break down bulk material in the input chamber 2. An open venturi 5 in the input chamber 2 is operable to deliver bulk material from the input chamber 2 to a mixing chamber 6 to further break down the bulk material. A second set of spaced-apart waterjets 8 mounted at an outlet of the mixing chamber 6 helps to remove clay from the aggregate material, all the material then being delivered through an upwardly inclined transfer pipe 10 to a dilution box 11 having an outlet 12 which discharges to an inclined vibrating rinsing screen 13.

Referring in particular to Fig. 1 to Fig. 4, the input chamber 2 is a generally rectangular box having a rectangular base 14 with upstanding side walls 15, 16 interconnected by upstanding end walls 17, 18. The first set of waterjets 3 comprise high pressure water pulse jets operating at a pressure of between 15 and 350 bar. A row of five waterjets 3 extend along a top of each side wall 15, 16 and are directed inwardly to smash incoming bulk material against impact bars and an anvil plate 20 at a top of the input chamber 2 to break up the incoming bulk material and separate clay from the aggregate material. Excess water is allowed to overflow from the top of the input chamber 2, removing light contaminants from the bulk feed material.

The open venturi 5 has an infeed waterjet nozzle 22 centrally mounted in one end wall 17 of the input chamber 2 and aligned with an inlet 23 of the mixing chamber 6. A jet stream of water from the nozzle 22 into the inlet 23 pulls in with it bulk material from the input chamber 2. The open venturi has a 32/34mm rifled nozzle 22 which will create a twisting vortex that will transport the 0 to 90mm bulk materials into the mixing chamber 6 where the bulk materials are scrubbed by the velocity, attrition and cavitation of the material, small and large particles colliding with each other to break down the water-soluble clay bound materials coating the bulk solid materials.

The mixing chamber 6 is generally cylindrical and is mounted on an opposite end wall 18 to the nozzle 22 in alignment with the nozzle 22. The mixing chamber 6 is constructed of a high chrome iron material and has a ceramic manganese metal insert which is replaceable when worn. The mixing chamber 6 may be rotatable to even out wear on an internal bore of the mixing chamber 6.

Four spaced-apart pulse jet nozzles 8 are mounted at an outlet of the mixing chamber 6. These nozzles 8 can be static or, more preferably, they are mounted on a rotating collar 26. Rotation of the collar 26 may be achieved by a variable speed electric or hydraulic motor. Alternatively, the jets 8 may be angled in such a way as to rotate the collar 26. These waterjets 8 inject high pressure water into the outlet end of the mixing chamber 6, forming a rotating vortex which obliterates clay bound material into a suspended solid which is later screened off with the 0 to 5mm material on the inclined vibrating rinsing screen 13. It will be noted that the venturi 5, mixing chamber 6 and transfer pipe 10 are in alignment and have a common central longitudinal axis A.

The transfer pipe 10 is formed by an abrasive resistant lined steel pipe and has a diameter in the order of 200-300mm and is inclined at an angle of between 22° and 25°, and preferably about 22° to the horizontal. A screw adjustment system for altering the transfer pipe 10 angle is provided. An outlet end 30 of the transfer pipe 10 connects to an inlet 31 of the dilution box 11. Both the mixing chamber 6 and the transfer pipe 10 are rotatable to equalize the wear pattern an extend their useful working life.

Fig. 5 and Fig. 6 show the transfer pipe 10 arrangement. The transfer pipe 10 is mounted on a support framework 70 and is rotatably supported on a number of paced-apart roller assemblies 71 on the support framework 70, the transfer pipe 10 resting on sets of rollers 72 at each roller assembly 71. When pipe locking bolts are released, a pipe lift system 74 supports the transfer pipe 10 when rotating the transfer pipe 10 to equalise the wear pattern inside the transfer pipe 10.

Referring in particular to Fig. 1 , Fig. 7 and Fig. 8, the dilution box 11 has a generally rectangular box housing 32 lined with a wear resistant material. Material entering through the inlet 31 is directed against a manganese wear plate 33 and rebounds against the incoming material and is then turned downwardly through 90° onto a full width of the dilution box 11. The outlet 12 of the dilution box 11 cooperates with the associated inclined vibrating rinsing screen 13 to discharge material from the dilution box 11 through the outlet 12 onto a full width of the inclined vibrating rinsing screen 13 for optimum efficiency. At a top of the inclined vibrating rinsing screen 13 is a rubberised reception box which absorbs the impact of the water and bulk feed material, thus protecting the screening medium from the impact of the bulk material which can be very abrasive.

A third set of high-pressure pulse jets 35 is mounted within the dilution box 11 at a top of the dilution box 11 to inject water into incoming material which will further break down the water-soluble clay bound material. A rotating blade system 36 may also be provided within the dilution box 11 to impact with the bulk material, breaking down any stubborn clay bound material prior to discharge through the outlet 12 to the inclined vibrating rinsing screen 13.

Fig. 9 and Fig. 10 show a mobile chassis 40, in this case having tracks 41 , of the system 1 . The system 1 is shown with an associated mobile infeed hopper 43 with screen 44 feeding an elevator 45 which discharges the bulk material to the input chamber 2. The mobile inclined vibrating rinsing screen 13 is positioned below the outlet 12 of the dilution box 11 to receive material discharged therefrom. Discharge conveyors 46, 47, 48 project laterally outwardly from the inclined vibrating rinsing screen 13 to discharge screened material in various sizes into stockpiles 49, 50, 51 .

Fig. 11 and Fig. 12 show a mobile bulk material processing system 60 according to the invention which incorporates the mobile aggregate scrubbing system 1 described previously. In this case the mobile bulk material processing system 60 additionally includes a jaw crusher 61 which discharges to an optional secondary jaw crusher or roller bearing cone crushing plant 62 which discharges bulk material to the screen 44 of the mobile infeed hopper 43. Downstream of the inclined vibrating rinsing screen 13 there is a mobile fines recovery plant 63, a mobile water recovery system 64 and a filter press 65.

Referring now to Fig. 13 to Fig. 15, there is illustrated an input chamber portion of a mobile aggregate scrubbing system according to another embodiment of the invention, having an alternative input chamber assembly, indicated generally by the reference numeral 70. Parts similar to those described previously are assigned the same reference numerals. In this case, the input chamber portion 2 is provided with a crushing system 71. The crushing system 71 comprises a set of cutting knives having a pair of outer cutting knives 72, 73 with an inner or central cutting knife 74 mounted therebetween. All of the knives 72, 73, 74 are mounted on a common pivot 75. In this case the common pivot is located above the input chamber 2. A first ram 76 is connected to upper ends of the outer cutting knives 72, 73 and a second ram 77 is connected to an upper end of the central cutting knife 74. Each knife 72, 73, 74 is cranked, having an upper shaft portion 78 and a lower knife portion 79 which extends into the input chamber 2 between the venturi 5 and the mixing chamber 6. Operation of the rams 76, 77 pivots the knives 72, 73, 74 about the pivot 75, moving the knife portions 79 of the two outer cutting knives 72, 73 and the central cutting knife 74 in a scissors action for crushing material therebetween.

Referring now to Fig. 16 to Fig. 18, there is illustrated an input chamber portion of a mobile aggregate scrubbing system according to a further embodiment of the invention, having an alternative input chamber assembly indicated generally by the reference numeral 80. Parts similar to those described previously are assigned the same reference numerals. In this case, an alternative arrangement of crushing system 81 is provided, having lower ends of the cutting blades 79 connected to the common pivot 75 which is located at a bottom of the input chamber 2, within the input chamber 2. Again, operation of the rams 76, 77 causes the blades 79 of outer cutting knives 82, 83 and an associated central cutting knife 84 therebetween, to move together and apart in a scissors action to crush material therebetween.

The terms “comprise” and “include”, and any variations thereof required for grammatical reasons, are to be considered as interchangeable and accorded the widest possible interpretation.

The invention is not limited to the embodiments hereinbefore described but may be varied in construction and detail within the scope of the appended claims.