AU708438B2

AU708438B2 - Pre-dewatering cone

Info

Publication number: AU708438B2
Application number: AU15283/95A
Authority: AU
Inventors: Don A. Johnson
Original assignee: TEMA ENGINEERS Pty Ltd
Current assignee: TEMA ENGINEERS Pty Ltd
Priority date: 1994-01-24
Filing date: 1995-01-23
Publication date: 1999-08-05
Anticipated expiration: 2015-01-23
Also published as: AU1528395A

Description

_~Ltl~ WO 95/19849 PCT/AU95/00031 -1- PRE-DEWATERING

CONE

BACKGROUND OF THE INVENTION The present invention relates to a centrifuge for the dewatering of particulate material, such as washed small coal or refuse.

In particular, the present invention relates to a "pre-dewatering cone" which is supplied within a centrifuge basket, of the kind which comprises a revolvable screen of substantially truncated conical shape, widening towards a discharge end.

DESCRIPTION OF THE PRIOR ART In the dewatering of washed coal or refuse, material is supplied through an inlet to the base portion of a centrifuge basket. The centrifuge is generally rotated and vibrated such that the particulate material supplied thereinto is essentially dewatered prior to it's release at a discharge end of the centrifuge basket.

Various attempts have been made in the past to redesign the centrifuge basket such that a more thorough dewatering process is achieved.

Such arrangements includes the provision of radial steps, as previously proposed for instance in Australian Patent No. 520314 (39982/78) assigned to Siebtechnik GmbH, of whom the Applicant is a wholly owned subsidiary. In such an arrangement, the vibratory centrifuge is rotated, and vibrated axially. The screen is of coned form, widening towards the discharge end. The material is supplied through the charging pipe with a distributing funnel. The revolving screen substantially comprises three truncated shaped sections, which are joined to one another by radially directed steps, so as to collectively provide a stepped revolving screen. In use, the stepping arrangement causes a loosening or rearrangement of the layers being moved to the discharge end, such that the final dewatered product has greatly enhanced characteristics.

The Applicant has also proposed an alternative arrangement to the radially stepped arrangement of Patent No. 520314. Such an arrangement is described in the Applicant's I I 11 11 1 M WO 95/19849 PCT/AU95/00031 -2co-pending application, which defines a centrifuge which comprises a revolvable screen which is provided with at least one lateral step. In the latter arrangement, a plurality of substantially quadrilaterally shaped sections are provided, with steps being provided between the edges of adjoining quadrilaterals. As the particulate material is provided in the centrifuge, it typically travels over each step a number of times prior to being discharged at the outlet. Consequently, a greatly improved dewatering process compared with the process utilising radially disposed steps, is enabled.

One of the problems associated with all centrifuge baskets of the kind which comprise a revolvable screen of substantially truncated conical shaped, is that, due to the configuration of the distributing funnel and the charging pipe to supply the material into the base portion of the centrifuge basket, the particulate material typically causes most wear on the basket in the region proximal to the base portion of the basket. That is, the basket most prone to wear at the small radius of the inner surface thereof, where the material to be dewatered is inputted.

SUMMARY OF THE INVENTION The present invention seeks to provide a centrifuge device which has an improved life span by providing a component which is readily replaceable as wear occurs.

The present invention seeks to provide a centrifuge device which utilises a predewatering cone provided in the central portion of the centrifuge basket.

The present invention seeks to provide a pre-dewatering cone which allows easy replacement in a less costly manner then replacing the whole basket.

The present invention also seeks to provide a device which increases the wear life of a conventional basket by providing a pre-watering cone which bears the brunt of the large initial forces of the particulate material entering the centrifuge device.

In one broad form, the present invention provides a pre-dewatering device adapted to be inserted internally in the base portion of a centrifuge basket, said cone being formed of perforated screen material and being of substantially similar shape but of small overall WO 95/19849 PCT/AU95/00031 -3dimensions than said basket.

Preferably, said cone is of substantially truncated conical shape.

Also preferably, said cone is provided with larger apertures than said basket, to effect pre-dewatering of coarse particles or agglomerates.

Most preferably, said cone is adapted to be attached to said basket in a readily removable manner.

In a preferred embodiment as particulate material travels from said cone to said basket, it passes through a radial step.

In an optionally preferred embodiment, the cone has at least one step in a lateral direction.

Preferably, said cone is comprised of a plurality of substantially quadrilaterally shaped sections, lateral steps being provided between edges of adjoining quadrilaterals.

Also preferably, said cone is comprised of a plurality of substantially trapezoidal shaped sections, lateral steps being provided between the edges of adjoining trapezia.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more fully understood from the following detailed description of a preferred but non-limiting embodiment thereof, described in connection with the accompanying drawings, wherein: Fig. 1 illustrates a prior art centrifuge arrangement, which is not provided with a pre-dewatering cone; Fig. 2 illustrates a centrifuge basket incorporating a pre-dewatering cone in accordance with the first embodiment of the present invention; Fig. 3 illustrates a centrifuge basket incorporating a pre-dewatering cone in accordance with the second embodiment of the present invention.

i_ WO 95/19849 PCT/AU95/00031 -4- DETAILED DESCRIPTION OF PREFERRED

EMBODIMENTS

A centrifuge configured in accordance with the present invention is provided with a pre-dewatering "cone" 1 within a screen basket 2, such as illustrated in Figs. 2 and 3.

Prior art centrifuges such as illustrated in Fig. 1, only use a basket. That is, they are not provided with a pre-dewatering cone 1. Such baskets are most prone to wear at the small radius of their inner surface, i.e. at the base portion of the basket, where the material to be dewatered is inputted.

The provision of a pre-dewatering cone 1, as shown in Fig. 2, allows easy replacement and less costly manner than replacing the whole basket 2. If desired, a different size filtration device, i.e. smaller or larger grids, may be supplied to facilitate a different rate of dewatering. The embodiment shown in Fig. 2 is of a standard format of a pre-dewatering cone, that is, of simply truncated conical shape, i.e. without steps.

Preferably, but not essentially, the pre-dewatering cone is constructed of material of larger aperture size than the aperture size of the basket 2. As the particulate material to be dewatered is supplied into the centrifuge, the larger particles, in particular, contact the large grid of the pre-dewatering cone 1, such that the pre-dewatering cone 1 absorbs the impact and causes certain dewatering of the material prior to then being provided via the step 3 onto the basket 2.

As mentioned hereinbefore, the Applicant has proposed an arrangement of a centrifuge which utilises a basket 2 having laterally disposed steps, to assist the dewatering process, which is the subject of a copending application for Patent. Such a stepped configuration is shown in Fig. 3. Also shown in Fig. 3, is a pre-dewatering cone 1 provided with laterally disposed steps 4.

Throughout the specification, when the term "laterally disposed step" or the like is used, it is intended to use any direction transverse to a radial plane direction (as described in Australian Patent No. 520314 (39982/78) by Siebtechnik GmbH). That is, it should be understood to include a step between the edges of adjoining polygonal sections which are joined to make up the substantially conically shaped screen whether the polygonal sections are substantially similar shape or not and/or to include steps _I i WO 95/19849 PCT/AU95/00031 provided in a spiral or helical shaped configuration of the screen, etc.

In operation, provision of laterally disposed steps on the basket 2, and/or the predewatering cone 1, enables an improved dewatering process to be achieved. It will be understood that in providing a radially stepped arrangement, as described in Australian Patent No. 520314, an improved dewatering process occurs compared with having a nonstepped arrangement. The provision of lateral steps, however, enables each particulate material to traverse a number of steps as the centrifuge rotates with number of which, of course, depend upon the number of sections making up the cone or the basket, and/or on the vibrational frequency and the angular velocity of the centrifuge.

It should be understood to persons skilled in the art that a pre-dewatering cone of any shape falls within the scope of this invention.

Whilst various preferred embodiments of the invention have been hereinbefore described, it should be understood that numerous variations and modifications will become apparent to persons skilled in the art. All such variations and modifications should be considered to fall within the scope of the invention as broadly hereinbefore described.

i;

Claims

1. A pre-dewatering device adapted to be inserted internally in the base portion of a centrifuge basket, said device being formed of perforated screen material and being of substantially similar shape but of small overall dimensions than said basket.

2. A pre-dewatering device as claimed in claim 1, wherein said device is of substantially truncated conical shape.

3. A pre-dewatering device as claimed in claim 1 or 2, wherein said device is provided with larger perforations than said basket, to effect pre-dewatering of coarse particles or agglomerates.

4. A pre-dewatering device as claimed in any one of claims 1 to 3, wherein said device is adapted to be attached to said basket in a readily removable manner.

A pre-dewatering device as claimed in any one of claims 1 to 4, wherein, in use, as particulate material travels from said device to said basket, it traverses a radial step.

6. A pre-dewatering device as claimed in any one of claims 1 to 5, having at least one step in a lateral direction.

7. A pre-dewatering device as claimed in claim 6, wherein said device is comprised of a plurality of substantially quadrilaterally shaped sections, lateral steps being provided between edges of adjoining quadrilaterals.

8. A pre-dewatering device as claimed in claim 7, wherein said device is comprised of a plurality of substantially trapezoidally shaped sections, lateral steps being provided between the edges of adjoining trapezia.

9. A pre-dewatering device, substantially as herein described with reference to the accompanying drawings. I a WO 95/19849 PCT/AU95/00031 -7- A method of pre-dewatering particulate material utilising a pre-dewatering device in a centrifuge basket substantially as herein described with reference to the accompanying drawings. 311 ,Irl r