WO1999002278A1

WO1999002278A1 - Gravitational fines classifier

Info

Publication number: WO1999002278A1
Application number: PCT/AU1998/000512
Authority: WO
Inventors: Denis Wagner
Original assignee: Wagner Investments Pty. Ltd.
Priority date: 1997-07-08
Filing date: 1998-07-06
Publication date: 1999-01-21
Also published as: NZ501905A; AUPO775497A0

Abstract

An apparatus and method for separating the fines from an aggregate conglomerate. The apparatus comprises an inclined bed (11) and a vertical partition (12) which are separated by a predetermined amount (X, Y). The aggregate conglomerate flows under gravity down the inclined bed such that the heavier aggregate passes into one compartment (20) on one side of the partition (12) and the fines pass into another compartment (21) on the upstream side of the partition (12).

Description

GRAVITATIONAL FINES CLASSIFIER BACKGROUND OF THE INVENTION THIS invention relates to an apparatus for separating the fines from an aggregate conglomerate. The invention is primarily concerned with the separation of material less than about 600 μm from crusher screenings of less than about 5.0 mm, and will be described in that context although the broader concept of separation is intended to be understood and form part of the overall inventive concept.

Sand supplies for construction purposes, particularly as a major component for the production of both hydraulic and asphaltic concrete, have become increasingly difficult and more expensive to obtain. This is due to the exhaustion of natural deposits and increasing pressure being brought to bear by an increasingly environmental aware society. Shortages of readily accessible reserves of natural sand is a dilemma which confronts the construction industry on a global scale. For these reasons it is imperative that an equitable alternative to natural occurring sand be developed.

The obvious alternative to naturally occurring sand is the fines present with crushed stone screenings, produced during hard rock quarrying operations. Generation of a suitable alternative or "stone sand", from these crusher fines, requires processing to remove powder like fines such as clay and other materials which would be considered deleterious for construction purposes. The resulting stone sand is highly suited to concrete production.

Currently stone sand is produced either by a dry processing technique using a forced draft, or by a wet processing technique using flotation. Such techniques are either expensive or environmentally hazardous, or both.

OBJECT OF THE INVENTION It is therefore an object of the invention to provide an apparatus for separating the aggregate fines, that is stone sand, from crusher screenings which is cost- effective, efficient and less environmentally hazardous that the existing systems, and/or which at least provides the public with an alternative choice to existing preparative techniques.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided an apparatus for separating aggregate fines from a mixture of aggregate fines and larger aggregate material, said apparatus comprising the combination of an inclined bed onto which the mixture can be loaded and an upstanding separation partition, wherein the inclined bed has a lower edge which is located at a predetermined spacing from an upper edge of the partition, said predetermined spacing being selected such that when an aggregate mixture moves down the bed and over the lower edge under gravitational forces, the larger aggregate falls to one side of the partition and the aggregate fines fall to the other side of the partition.

DETAILED DESCRIPTION OF THE INVENTION

Preferably, the inclined bed and separation partition are mounted within a box-like structure. The box-like structure provides support for the partition and the bed, and containment for the aggregate mixture and the separated components thereof. The box-like structure suitably has an open top to enable the aggregate mixture to be conveyed or dropped on to the upper region of the inclined bed. Separate compartments within the box-like structure are provided for the aggregate fines and larger aggregate material to pass into immediately upon separation.

The inclined bed upon which the mixed aggregate is loaded for sliding under gravitational forces can be flat, curved or irregularly shaped. Typically it is a rectangular plate which is angled between 30° and 60°, most preferably about 45° with respect to the vertical. The inclined bed will suitably be constructed out of a relatively wear resisting material such as plate steel having a ceramic coating and will be removably fixed in place in the box-like structure to enable replacement or removal for repair, or for the purpose of altering its inclination. The separation partition is preferably a rectangular panel which extends vertically below the lower edge of the inclined bed to the bottom of the box-like structure. The spacing of the top edge of the separation partition from the bottom edge of the inclined bed is suitably adjustable to suit the grade of mixed aggregate from which the fines are to be separated. Typically, the vertical separation is from .2 mm to 15 mm and the horizontal separation is from .8 mm to 15 mm.

Since the separation partition is also subject to wear, the separation partition can be fabricated from wear-resisting material, such as ceramic-coated steel plate. However, as only the top edge of the separation partition is subject to extreme wear, only this region need be coated. However, as an alternative to this a wear-resisting adjustable and removable tip in the form of a flat strip, is preferred from a cost point of view. Such a wear-resisting tip has the further advantage in that it can be readily replaced by unfastening it from the separation partition. It can also be adjusted in height by the fasteners, to control the amount of separation from the bottom edge of the inclined bed.

The apparatus according to the invention is particularly suitable for classifying crushed stone screenings to produce a stone sand for use in the production OF hydraulic and asphaltic concrete. In that context, the apparatus gives rise to a method which has significant cost advantages over existing separation methods and there are substantially no environmental hazards involved. The method is a second aspect of the invention.

According to the second aspect of the invention there is provided a method for separating aggregate fines from a mixture of aggregate fines and larger aggregate material, which method comprises passing the mixture down an inclined bed under gravitational forces, said inclined bed having a lower edge separated from an upper edge of an adjacent partition by such an amount that the larger aggregate falls to one side of the partition and the aggregate fines fall to the other side of the partition.

Figure 1 is a cross-sectional view of a separating apparatus according to the invention, and

Figure 2 is a schematic perspective view of the apparatus depicted in Figure 1.

DESCRIPTION OF PREFERRED EMBODIMENT A preferred embodiment of the invention will now be described with reference to the drawings. In both of the drawings, like reference numerals refer to like parts.

Referring to both drawings simultaneously, the apparatus comprises a rectangular base box-like structure 10 in which are located a flat surfaced inclined bed 11 and a separation partition 12.

The box-like structure 10 is fabricated from plate steel and comprises five rigid walls 13, 14, 15, 16 welded together with rectangular corners. Outlets 17, 18 are provided in the bottom wall 14 to enable the separated materials to be removed from the respective compartments or to pass straight out of the compartments upon arrival.

The inclined bed 11 is a rectangular steel plate having a wear-resisting ceramic coating on its upper- facing surface. The bed is inclined at approximately 45° and is bolted at that angle by bolts (not illustrated) extending through the side walls 14, 16 of the box- like structure . The separation partition 12 is supported substantially vertically within the box-like structure such that its upper edge is at a spacing defined by coordinates X, Y from the lower edge of the inclined bed. The separation partition can be moved laterally to change the distance X by screw-threaded bolt connections or other such means (not illustrated) which extend to the separation partition through the walls of the box-like structure .

The distance Y can be altered by raising or lowering a wear-resisting strip 19 which is attached to the top-edge of the separation partition. Alternatively, the entire separation partition can be raised or lowered.

The wear-resisting strip is a ceramic coated steel plate.

In operation, crusher screenings and fines are loaded onto the top of the inclined bed 11 from a flat bed feeder or like device. The crusher screenings and fines travel down the bed under gravitational forces. The heavier and larger screenings have a greater momentum than the lighter fines and are carried over the separation partition into the compartment 20 while the lighter and smaller fines do not move so fast and are blocked in their forward trajectory by the upper edge of the separation partition, that is, by the wear-resisting strip 19, and fall into compartment 21. The fines and coarse screenings are then separately removed from their respective compartments .

Whilst the above has been given by way of illustrative example of the invention, many modifications and variation may be made thereto by persons skilled in the art without departing from the broad scope and ambit of the invention as herein set forth.

Claims

1. An apparatus for separating aggregate fines from a mixture of aggregate fines and larger aggregate material, said apparatus comprising the combination of an inclined bed onto which the mixture can be loaded and an upstanding separation partition, wherein the inclined bed has a lower edge which is located at a predetermined spacing from an upper edge of the partition, said predetermined spacing being selected such that when an aggregate mixture moves down the bed and over the lower edge under gravitational forces, the larger aggregate falls to one side of the partition and the aggregate fines fall to the other side of the partition.

2. An apparatus as claimed in claim 1, wherein the inclined bed and the separation partition define two walls of a compartment into which the aggregate fines pass for initial collection.

3. An apparatus as claimed in claim 2, including a compartment into which the larger aggregate material passes, wherein the separation partition defines one wall of such a compartment .

4. An apparatus as claimed in claim 1, which is mounted within an open-top box-like structure including outlets through which the separated fines and larger aggregate material can separately pass.

5. An apparatus as claimed in claim 1, wherein the inclined bed has a flat or curved configuration.

6. An apparatus as claimed in claim 5, wherein the inclined bed is a flat rectangular plate having a wear resisting coating.

7. An apparatus as claimed in claim 6 , wherein the plate is a steel plate with a ceramic coating.

8. An apparatus as claimed in claim 1, wherein the inclined bed is angled between 30° and 60° with respect to the vertical.

9. An apparatus as claimed in claim 8, wherein the angle of inclination is approximately 45° with respect to the vertical.

10. An apparatus as claimed in claim 1, wherein the separation partition extends in a substantially vertical arrangement .

11. An apparatus as claimed in claim 10, wherein the separation partition is a rectangular panel.

12. An apparatus as claimed in claim 11, wherein the panel is a steel plate which has a partial ceramic coating .

13. An apparatus as claimed in claim 1, including a wear-resisting tip extending along the upper edge of the partition.

14. An apparatus as claimed in claim 13, wherein the wear-resisting tip is adjustable in height with respect to the partition and can be readily removed from the partition.

15. An apparatus as claimed in claim 14, wherein the wear-resisting tip is a ceramic-coated strip of steel.

16. An apparatus as claimed in claim 1, wherein the spacing between the lower edge of the inclined bed and the upper edge of the partition is within the vertical parameters of from 0.2 mm to 15 mm and within the horizontal parameters of from 0.8 mm to 15 mm.

17. An apparatus as claimed in claim 1, which is suitable for separating aggregate fines having a mean diameter of less than about 600 μm from larger diameter aggregate having a mean diameter of less than about 5.0 mm.

18. An apparatus for separating aggregate fines from a mixture of aggregate fines and larger aggregate material substantially as herein described with reference to the accompanying drawings .

19. A method for separating aggregate fines from a mixture of aggregate fines and larger aggregate material, which method comprises passing the mixture down an inclined bed under gravitational forces, said inclined bed having a lower edge separated from an upper edge of an adjacent partition by such an amount that the larger aggregate falls to one side of the partition and the aggregate fines fall to the other side of the partition.

20. A method for separating aggregate fines from a mixture of aggregate fines and larger aggregate material substantially as herein described with reference to the accompanying drawings .

AMENDED CLAIMS

[received by the International Bureau on 06 October 1998 (06.10.98); original claim 1 amended; remaining claims unchanged (4 pages)]

1. An apparatus for separating aggregate fines from a mixture of aggregate fines and larger aggregate material, said apparatus comprising the combination of an inclined bed onto which the mixture can be loaded and an upstanding separation partition, wherein the inclined bed has a lower edge^' which is located at a predetermined spacing from an upper edge of the partition, said predetermined spacing being selected such that when an aggregate mixture is loaded onto an upper region of the bed and moves down and along the bed and over the lower edge under gravitational forces, the larger aggregate falls to one side of the partition and the aggregate fines fall to the other side of the partition.

3. An apparatus as claimed in claim 2 , including a compartment into which the larger aggregate material passes, wherein the separation partition defines one wall of such a compartment .

4. An apparatus as claimed in claim 1, which is mounted within an open-top box-like structure including outlets through which the separated fines and larger aggregate material can separately pass .

7. An apparatus as claimed in claim 6, wherein the plate is a steel plate with a ceramic coating.

9. An apparatus as claimed in claim 8 , wherein the angle of inclination is approximately 45° with respect to the vertical.

11. An apparatus as claimed in claim 10, wherein the separation partition is a rectangular panel .

12. An apparatus as claimed in claim 11, wherein the panel is a steel plate which has a partial ceramic coating.

14. An apparatus as claimed in claim 13 , wherein the wear-resisting tip is adjustable in height with respect to the partition and can be readily removed from the partition.