WO2006060850A1

WO2006060850A1 - Improvements in dewatering apparatus

Info

Publication number: WO2006060850A1
Application number: PCT/AU2005/001819
Authority: WO
Inventors: Peter Geoffrey Herbert
Original assignee: Delkor Pty. Ltd.
Priority date: 2004-12-08
Filing date: 2005-12-05
Publication date: 2006-06-15

Abstract

A suction tank (7) of dewatering apparatus is composed of a line of plastics boxes (11) connected to one another and to the underside of a plastics slide plate (8) which extends horizontally above the tank. The tank (7) is bodily vertically movable between a lower maintenance position and a raised operating position. The slide plate (8) is provided with parallel guide channels (103) and downwardly-leading drainage openings (104,105) for draining liquid washed through the belt into the suction tank (7) beneath. The guide channels (103) contain the lower part of the thickness of respective wear- absorbing belts which hold a porous belt above the surface of the guide plate 8. The plastics boxes (11) are light, chemically inert, and can be manhandled by one or two people. They also have the advantage that the suction tank (7) can be assembled from a line of bolted-together moulded plastics boxes transported to the site of the de- watering apparatus.

Description

IMPROVEMENTS IN DEWATERING APPARATUS

Field of the invention

THIS INVENTION relates to mineral ore extraction and is more specifically, although not exclusively, concerned with apparatus for removing water from a traveling bed of particulate material. Such apparatus is known widely in the industry as "de-watering apparatus" even though it may be used for removing non-aqueous liquids as well as or instead of water. Thus the expression "de-watering apparatus" is to be understood in the context of this specification as applying to apparatus for removing any liquid, not necessarily water, from a traveling bed of particulate material. The bed of particulate material may, for example, be a wanted mineral ore in pulverized form that has been separated from unwanted particulate material by a flotation process or other extraction technique.

State of the art

Ore extraction plant located at a mining site normally includes pulverizing mills for reducing rocks containing the wanted mineral to a particulate form and supplying it for instance to separation tanks containing a liquid through which air is blown. The liquid may contain chemicals selected because of their property of causing the wanted mineral particles to collect in a froth of air bubbles that collects in the top of the separation tanks. The froth is fed from the tanks to apparatus that removes the froth liquid from the bed and collects it for recycling through the separation tanks. The bed of wanted particulate material, now free from froth, is washed with a suitable water- miscible solvent to remove the last of the froth liquid from the bed, and the bed of particulate material is finally washed with water to remove the residual solvent for collection and recycling through the plant. The washed bed of particulate material is then dried and transferred elsewhere for further treatment. The above extraction plant normally operates on a continuous flow basis and in most cases includes de-watering apparatus utilizing a traveling belt to assist removal of wash liquids from the bed of particulate material. The froth containing the wanted particulate mineral as well as liquid is deposited on one end of an upper horizontal run of the traveling belt that is of porous construction to enable wash liquid to run through it. The bed of particulate material is carried along by the belt run. The liquid from the froth flows down through the bed of particulate material and the porous belt beneath, and is collected in a suction tank beneath the upper run of the belt. Corrosion-resistant steels are normally used for making the suction tank as liquids used in the extraction process may be corrosive. The tank is of extended length - often being ten or more meters long - and normally has to be maintained at a low pressure in order to suck liquid from the bed of particulate material. The upper part of the walls of the tank engage a wear- absorbing arrangement beneath the upper run of the porous belt and over which the belt passes. Suction nozzles in the sides of the tank maintain the low tank pressure and provide outlets through which wash liquid sucked into the tank can be removed from it together with any particulate material escaping with it. The wash liquid is may then be passed into separators for isolating any re-usable and possibly expensive components for recycling. Partitions may be spaced lengthwise of the tank to enable the different wash liquids to be kept separate from one another.

An extraction plant containing de-watering apparatus is normally sited close to the source of mined ore material, for economic reasons. As the plant is large and expensive, its parts are fabricated elsewhere and assembled at site. Not only are corrosion-resistant steels used in the construction of the suction tank often expensive to purchase, they may be relatively heavy and awkward to move around, and have to be transported in lengths of substantial size to the site of use. They then have to be machined at the site to provide the required outlets, suction nozzles and other fixtures which are used in conjunction with the tank. Such machining can also be expensive. For all of these reasons the cost of the suction tank represents a relatively large part of the cost of the de- watering apparatus and thus the overall cost of the plant. Object of the invention

An object of this invention is to provide improved de-watering apparatus.

The invention

A suction tank of de- watering apparatus made in accordance with the present invention, contains a line of similar open-topped boxes made from a relatively inert plastics material and arranged beneath an upper run of an endless porous belt.

Advantages of the invention

The substitution of a line of plastics boxes for steel plate represents a substantial saving in cost as inert plastics materials are currently available at cheaper prices than steel. Also, as the boxes can be individually inserted into, and removed from the line of boxes, the suction tank can be made of an almost infinite length and from standard components. Any necessary repairs can be carried out easily as a damaged plastics box can be removed from the line of boxes and replaced with a new one. Also, plastics, being lighter than steel, enables the boxes to be fabricated away from site, transported to the site, manhandled, and assembled together relatively cheaply. As each box need only be a meter long, its weight and dimensions can be arranged so t hat it can be lifted easily by one or two men. The inert plastics material is also generally more corrosion- resistant than steel plate.

Preferred features of the invention Preferably the tank is constructed from a line of boxes which are identical with one another. The line of boxes is preferably mounted on a frame in a way which allows the suction tank to expand thermally in a longitudinal direction. The frame may also be arranged so that it can be raised and lowered bodily between two positions. At the lowered position, the boxes are spaced beneath the upper run of the porous belt so that each box can be readily inspected and replaced if necessary. In the raised position an effective pneumatic seal is formed so that the suction in the tank is applied to the underside of the upper run of the porous belt. Each box may be pre-formed with an outlet nozzle suitably positioned in its lower portion and to which a flexible liquid outlet coupling may be attached. Instead of having the outlet nozzles preformed in the lower portion of the box, the box may be pre-molded with at least one weakened zone which can be broken away, if required, to provide an opening to which a flexible suction coupling can be attached.

Suitably each box is formed with flanges at its ends having fixtures, such as holes, to enable the boxes to be bolted or otherwise attached to one another. This form of construction results in a rigid suction tank. The flanges may be provided with central through openings that enable suction applied to one or both ends of the tank to be present in each of the boxes. Removable partitions may also be provided in the tanks to compartment them, if required, to ensure that liquids flowing into different parts of the tank are kept separate from one another.

It is convenient to provide each box with laterally-extending lips at its upper edges, such lips forming a relatively smooth surface over which an apertured slide plate can be bolted to hold the boxes in position. The upper surface of the plate is suitably provided with one or more parallel guide channels each of which can hold an upper run of a respective wear-absorbing belt used to space the porous belt above the upper surface of the slide plate. The depth of the channel is preferably less than the thickness of the wear-absorbing belt to achieve this result.

Introduction to the drawings

The invention will now be ''described in more detail, by way of example only, with reference to the accompanying largely diagrammatic drawings, in which: -

In the drawings

FIGURE 1 shows in sketches A and B schematic side views, partly broken away, of the main parts of a de- watering apparatus, sketch A showing a suction tank of the apparatus in its raised position, and sketch B showing the suction tank in its lowered position; FIGURE 2 is a perspective view from above, of a line of three suction boxes forming part of the suction tank and bolted to one another and to t he underside of a slide plate;

FIGURE 3 is a perspective view of one of the suction box of figure 2;

FIGURE 4 is a vertical transverse section through one of the suction boxes of figure 3 taken on the line and in the direction of the arrows IV-IV in figure 3;

FIGURE 5 shows a vertical transverse section through a- first modification of the box of figure 3;

FIGURE 6 is a vertical transverse section through a second modification of the box of figure 3 and shows its attachment to the underside of a slide plate; and,

0 FIGURE 7 is a top plan view of part of the slide plate of figure 6.

Description of the first embodiment

Figures IA and IB show de- watering apparatus 1 comprising an elongated framework 2 supporting an upper horizontal run 3 of an endless porous filtering belt 4 that has a return run passing back through the framework at a distance beneath the run 3. The 2 upper run 3 of the belt 4 is supported on a pair of spaced, parallel, wear-absorbent belts 5 that pass around pairs of co-axial pulleys 6 at the opposite ends of the framework 2. One of the pairs of pulleys 6 is driven so that the movement of the wear-absorbent belts 5 is imparted to the belt 4 and causes its upper run 3 to travel at a pre-determined speed in a required direction. The upper parallel runs of the two belts 5 respectively run in _Q guide channels 103 formed in the upper surface of a plastics slide plate 8. The thickness of the belts 5 is greater than the depth of the channels 103 so that the upper surfaces of the belts 5 hold the undersurface of the upper run 3 of the porous belt 4 clear of the upper surface of the slide plate 8. The space between the belts 5, shown more clearly in figure 2, allows liquid passing through the belt 4 to flow downwards between the belts 5 and into a drain slot 105. The floor of the drain slot 105 is formed with elongated vertical apertures providing drainage ducts leading downwardly into a suction tank 7 located beneath the slide plate 8. The slide plate 8 provides a relatively low coefficient of friction with the underside of each of the wear-absorbing belts 5 passing over it so ⁵ that the wear on the porous belt 3 is reduced.

Each channel 103 has a central drain slit 104 formed in its underside and leading through openings (not shown) extending downwardly to the suction tank 7 beneath.

The framework 2 is provided with a vertically moveable lower portion 9, shown in figure IB, which supports the weight of the suction tank 7 and is bodily moveable 1° parallel to itself by actuators 10 between the two vertically-displaced positions shown respectively in figures IA and IB. Figure IA shows the tank in its operating upper position and IB shows the tank 7 in its lowered maintenance position. The slide plate 8 has the suction tank 7 bolted to its underside and it participates in the vertical movement to provide access to the wear-absorbing belts 5 when required.

15 Figure 2 shows parts of the tank 7 in more detail. In the example illustrated it comprises a line of connected-together suction boxes 11 of elongated rectangular shape as shown in figure 3 and of channel-shaped cross-section as shown in figure 4. The line of boxes 11 bolted to the underside of the plastics slide plate 8 provides a unitary structure. The channels 103 allow differential thermal expansion to occur between the metal

„ framework 2 on the one hand, and the slide plate 8 together with the attached metal boxes 11 on the other hand.

A vertical upright flange 12 is provided at each end of each box 11. Each flange 12 has an opening 13 at its centre so that suction applied by way of one or both openings 13 at the two remote ends of the suction tank 7 is effective in all of the boxes 8. The 25 contiguous flanges 12 of the boxes are held together by bolts 113. Each of the boxes 11 is molded from a hard inert plasties material and is about one meter long. Its weight is such that it can be carried by one man. External ribbing 14 adds strength to the box 11 each of which is integrally formed along the upper edges of its sidewalls with an outwardly turned lip 15 as shown in figure 3. The lips 15 at each side of the boxes 11 are aligned with one another to provide a coplanar upper surface beneath the slide plate 8 and they are formed with vertical bolt holes 117 enabling them to be bolted firmly to the underside of the slide plate 8.

Three vertical spaced nozzles 17 are integrally formed with, and extend vertically down from the floor of the box 11 and one or more of them may be closed or connected to a flexible liquid outflow pipe (not shown) to carry liquid from the box 11 to a treatment unit (not shown) which cleans the liquid and returns it for recycling through the de- watering unit.

Each of the nozzles 17 leading from the floor of each box 8, has a vertical axis. Flexible couplings (not shown) are attached to those of the nozzles 17 which are in use. This facilitates vertical movement of the suction tank 7 because the couplings do not have to be first disconnected from the floors of the boxes 11. The couplings, being flexible, allow thermal expansion of the suction box to occur with respect to the metal framework 2.

The mounting of the boxes 11 in the lower portion 9 of the framework 2 is such that when it is in its lowered position they can be individually unbolted from the neighboring boxes 11 and the slide plate 8, and replaced after the couplings to the nozzles 17 have been disconnected. Parallel link mechanisms 18 and associated bell- crank levers 50 attached to horizontal pivotal axes 19 enable the lower portion 9 of the framework 2 to be raised and lowered parallel to itself between its operating and maintenance positions.

As shown in figures 3 and 4, vertical pairs of parallel ribs 114 protrude opposite one another into the interior of the box 11 from its sidewalls as shown in figures 3 and 4. These enable partitions (not shown) to be placed at required positions along the box 11 so that different wash liquids discharged into the suction tank 7 can be kept separate from one another.

Operation of the first embodiment When the de-watering apparatus is in use, the upper run 3 of the belt 4 has progressively loaded onto it a froth containing particulate material that is to have the froth liquid washed from it, collected, cleaned and re-cycled through the apparatus. The belt run 3 passes beneath sprays of various liquids that wash out the froth so that it flows downwardly through the porous belt 3 and the drainage openings provided in the slide plate 8, and into the boxes 11 of the suction tank 7 beneath. The downward flow of liquid is assisted by a reduced pressure maintained in the suction tank 7 by way of suction applied to its end openings 13. The liquid collecting in the boxes 11 of the suction tank 7 is continuously drawn off by way of the nozzles 17 in its floor and the flexible couplings (not shown), and is collected for recycling through the plant.

As the bed of particulate material deposited on the upper run of the belt travels over the de-watering apparatus, it is progressively cleaned to a condition at which it can be collected and dried after it has reached the other end of the belt run.

If maintenance of the wear-absorbing belts 5 or the suction tank 7 becomes necessary, the lower portion 9 of the framework holding the suction boxes 11 is lowered. To remove any of the suction boxes 11 it is unbolted from its flanking boxes 11 and the slide plate 8. The flexible pipe couplings can then be uncoupled from the nozzles 17. The box 11 is then detached from the line of boxes and a new one of identical shape is fitted in its place and bolted into position. As the box 11 is made of a hard plastics material, it is light and relatively cheap to manufacture, and can be manhandled by one person quite easily. Its life is also long as its material is chosen to be relatively inert to the liquids passing through the de-watering apparatus. The suction tank composed of a line of similar plasties boxes 11 disclosed in this specification enables the cost of operating de-watering apparatus to be reduced and the current cost of plastics material enables the cost of manufacturing the apparatus to be reduced also.

Modification of first embodiment

Figure 5 shows a different shape of plastics box 30 to that shown in earlier figures and it is referenced 30. It is of a generally V-shape in section and has convergent side walls 31 and 32 which meet in a narrow floor 33. The box 30 has vertical end walls 35 so that similar boxes 30 can be bolted together as described above with reference to earlier figures, and also to the underside of a plastics slide plate (not shown) similar to that shown at 8 in figure 2.

The advantage of this shape of suction box is that it is lighter and cheaper than the suction box of earlier figures, as less plastics is used in its construction. It is also easier to carry and can be stacked together more compactly for ease of transportation. The convergent side walls 31,32 enable a given volume of wash liquid to collect in it with a greater depth than in the box shown in figure 4. This facilitates removal of the liquid from the box 30. Also, the positioning of outlet nozzles 34 at right-angles to the convergent sidewalls reduces the depth of the box and makes the lowering and maintenance of the suction tank easier as well as giving better access to the outlet nozzles 34 through which liquid is removed from the box 30.

Second modification of first embodiment

In the modification shown in figures 6 and 7 the suction tank is composed of a line of suction boxes 40 one of which is shown in vertical transverse section. As is apparent from figure 6 it is of roughly rhomboidal shape. Each box.40 is supported by a pair of outwardly-directed upper lips 41 whose upper surfaces are flat and coplanar. Down- turned flanges 42 extend along the edges of the lips 41 and are engaged by lower limbs 43 of C-shaped brackets 44. An elongated plastics slide plate 45 extends over the tops of the lips 41 and is formed with lateral grooves 46 which respectively accommodate upper limbs 47 of the brackets 44 as shown.

The lower limbs 43 of the brackets 44 are provided with openings enabling bolts 48 to be passed upwardly through them and through registering holes 49 formed in the lips 41. The bolts 48 extend into threaded openings 60 in the underside of the slide plate 45. The action of screwing up the bolts 48 is to force the brackets 44 upwardly so that they engage the ends of the flanges 42 and press the lips 41 upwardly and tightly against the underside of the slide plate 45. The lower portions of the box 40 are equipped with nozzles 54 in their convergent side walls 55. Flexible couplings 52 are attached to the nozzles 54 and allow the suction tank formed by the line of boxes 40 to be raised and lowered.

In figures 6 and 7 parts of the slide plate 45 identical to corresponding parts of the slide plate 8 illustrated in the first of the above embodiments, are similarly referenced except that the references are primed, and these parts will not be again described. Also, the drainage ducts leading down through the slide plate 45 from between the wear absorbing belts 5', are formed by oblong slots referenced 110 in these figures.

With the arrangement shown in figures 6 and 7 the vertical space occupied in the framework 2 by the line of suction boxes 40 is reduced and thus the framework can be reduced in size and the costs reduced also.

Claims

1. A suction tank of de- watering apparatus containing a line of similar open-topped boxes made from a relatively inert plastics material and arranged beneath an upper run of an endless porous belt.

2. A tank as claimed in claim 1, in which the boxes are identical to one another.

3. A tank as claimed in claim 1 or claim 2, in which the boxes of the suction tank are detachably secured to the underside of a plastics slide plate having at least one guide channel formed in its upper surface for the reception of a run of a wear-absorbing belt which protrudes above the channel and supports a porous belt at a position spaced above the upper surface of the slide plate.

4. A tank as claimed in claim 1, claim 2 or claim 3, mounted on a part of a framework which can be raised and lowered parallel to itself to move the tank between an upper working position and a lowered maintenance position.

5. A tank as claimed in any one of the preceding claims, in which downwardly- extending outlet nozzles on the boxes have associated flexible couplings connected to them.

6. A tank as set forth in any one of the preceding claims, in which pairs of parallel ribs are provided on the insides of the boxes to locate marginal edges of removable partitions used to divide the tank into longitudinally-spaced sections.

7. A tank as claimed in any one of the preceding claims, in which the boxes have end flanges bolted together face-to-face and formed with registering openings permitting suction to be applied througout the tank by way of its ends. ^•

8. A tank as claimed in any one of the preceding claims, in which each box has the upper part of its side-walls formed with outwardly-extending horizontal lips formed with holes through which bolts can be passed to attach the box to the underside of a, or the plastics slide plate which extends horizontally above the box.

5 9. A tank as claimed in any one of the preceding claims, in which the boxes have downwardly convergent lower side walls formed with outlet nozzles externally connected to flexible couplings and extending laterally away from the side walls.

10. Apparatus as claimed in claim 4 or any one of claims 5 to 9 when dependant on claim 4, in which the movable part of the framework is supported by parallel links and -^_Q actuator units operable in unison to raise and lower said movable part parallel to itself.