WO1995011076A1

WO1995011076A1 - Slurry separator

Info

Publication number: WO1995011076A1
Application number: PCT/GB1994/002305
Authority: WO
Inventors: Joseph Gardner
Original assignee: Joseph Gardner
Priority date: 1993-10-21
Filing date: 1994-10-20
Publication date: 1995-04-27
Also published as: AU7944694A; GB9321705D0

Abstract

A separator for separating solid material from slurry. The separator comprises a drum which is rotatable about a vertical axis and has a tubular perforated wall. Liquid passing through the perforated wall is discharged to an appropriate output, and solid material deposited on the inner surface of the wall is scraped off the drum wall and transported vertically upwards by a scraper in the form of, for example, an auger. The displaced material is discharged from an outlet at the top of the drum. The auger may be rotated about the same axis as the drum but at a different speed from the drum.

Description

SLURRY SEPARATOR

The present invention relates to a separator for separating solid material from slurry.

Mechanical separators are well known for reducing the solids content of for example agricultural slurry. The known separators operate on the principle of compressing the slurry against a perforated screen such that liquid passes through the screen and solid material is retained. The retained solid material is then transported across the screen to a discharge point by brushes or the like.

Most of the machines currently in use comprise a static perforated screen defining an open-topped trough into which slurry is pumped. Brushes sweep across the inner surface of the trough, carrying solid material to an upper edge of the screen and pushing the material over that edge to a . discharge outlet. It has been found with such machines that they will only operate efficiently if the slurry is dilute, that is having a maximum solid content of the order of 6%. This can be achieved by adding previously separated liquid to new slurry or by over-pumping the slurry feed to the machine and allowing excess to flow back to source. This approach results in a significant pumping energy requirement.

The known machines are also disadvantageous from the point of view of their size and appearance. Separators are typically mounted on steelwork of 3 to 5 metres in height and can have an overall height of the order of 7 metres. Such structures are not acceptable in some areas where the local populace is sensitive to changes in the appearance of the environment.

In another known separator, a drum is arranged to rotate about a horizontal axis and slurry is fed to the outer surface of the drum. Static brushes and rollers^' dislodge solid material from the surface of the drum, liquid entering the drum being discharged to a liquid outlet at one end. It has been found that the throughput of such machines is greater than in the case of static screen devices but reliability has been a problem.

There are of course other separators available, for example a device which operates by compressing slurry within a perforated drum against an end plate, belt press type separators and the like. Such arrangements are generally only commercially viable in very large installations.

It is an object of the present invention to provide a slurry separator which obviates or mitigates the problems outlined above.

According to the present invention there is provided a separator for separating solid material from slurry, comprising a drum having a tubular perforated wall and arranged with its major axis inclined to the horizontal, means for rotating the drum about its major axis, an outlet for the discharge of liquid passing through perforations in the drum wall, scraping means mounted within the drum so as to dislodge solid material from the radially inner surface of the drum wall, and an outlet for solid material located at the upper end of the drum, the scraping means being arranged to cause the transport of solid material dislodged from the drum upwards towards the outlet.

Preferably the drum axis is substantially vertical. The scraping means may comprise an auger radially outer edges of which act as scrapers to dislodge solid material from the drum wall, the auger being arranged such that dislodged solid material is carried by the auger to the solids outlet.

Preferably the scraping means is rotatable about the major axis of the drum, the scraping means being rotated at a different speed from the drum so as to maintain relative movement between the scraper and the drum.

The scraping means may support brushes that bear against the radially inner surface of the drum wall. Slurry may be pumped into a lower portion of the drum by for example an auger, the auger being supported in a lower portion of the drum which in use is dropped into a body of slurry.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawing.

Referring to the drawing, the schematically illustrated device comprises a drum having a tubular perforated upper wall 1, a frustoconical middle section 2 and a lower tubular section 3. The frustoconical section of the drum is supported on rollers 4 so as to be rotatable about a vertical axis 5.

An auger 6 is mounted on a rotating shaft 7 driven by a drive unit 8 which could be, for example, an electric motor or a coupling which could be connected to a tractor power take-off via a suitable gear box. The auger is journalled at its lower end in a tubular bearing 9 which rotates with the drum.

An upper flange 10 projects above the upper edge of the perforated drum section 1 and a lower lip 11 extends downwards into a liquid outlet 12. An outer casing wall 13 traps water passing outwards through the wall of the perforated drum section 1. The outer casing is supported on a suitable support structure indicated schematically by struts 14.

In use the lower end of the drum is lowered into a body of slurry indicated generally by reference numeral 15 within a slurry container which could be for example a concrete pit. The auger 6 is then driven relative to the drum so as to draw slurry up into the main body of the drum. The drum rotates and centrifugal force causes liquid within the slurry to be thrown out through the perforated wall section 1 to be collected via outlet 12. In the absence of any device to scrape solid material from the inner surface of the perforated drum wall 1 the perforations would rapidly become clogged and accordingly an auger 16 is located within the drum, the radially outer edges of the auger acting as scrapers to dislodge material from the radially inner surface of the drum. The auger is rotated at a lower speed than the perforated drum section 1 and serves to transport solid material dislodged from the perforated drum wall in an upwards direction until the material is deposited on the flange 10. The material is then flung outwards by centrifugal force to be discharged through an outlet 17. Thus the auger serves not only to prevent clogging of the perforations in the drum but also to transport the dislodged material to a convenient collection point.

The drive mechanism for the various rotating components has not been illustrated in detail. Any functionally suitable arrangement could be employed. For example, the two augers and the perforated drum could all be driven by a single power source through an appropriate gear train.

The radially outer edges of the auger may support brushes which engage the perforated wall of the drum to improve the cleaning effect and also to improve the ability of the auger to transport dislodged material vertically upwards. It may be possible to operate a device of the type described with a stationary auger or other scraping devices to clean the inner surface of the perforated drum, but it is considered preferable to rotate the scraping device as well as the drum so that the solid material is transported at a relatively low rate and that sufficient time is provided for liquid to be squeezed therefrom.

In the illustrated arrangement a simple auger is used to pump slurry into the rotating drum. In some circumstances it might be preferable to have an independently driven centrifugal pump or the like either located in the lower part of the drum or connected thereto by a suitable pipe which would enable the operation of the device on, for example, a trailer drawn up adjacent a slurry pit.

Thus embodiments of the invention can be envisaged which can be placed directly within a pit containing slurry, thereby eliminating the need for pumps and pipework to the machine, reducing the overall height and thereby creating less of an eyesore. Alternatively or in addition, the equipment could be made highly mobile and could therefore be used by contractors or on a cooperative basis, further spreading the availability and advantages of efficient slurry separation at an acceptable cost.

The throughput of a machine as described above should be far greater than in prior art devices, again making it suitable for use on more than one site. Furthermore it should be capable of processing relatively large volumes of material, thereby reducing the energy demand for a given volume.

Claims

1. A separator for separating solid material from slurry, comprising a drum having a tubular perforated wall and arranged with its major axis inclined to the horizontal, means for rotating the drum about its major axis, an outlet for the discharge of liquid passing through perforations in the drum wall, scraping means mounted within the drum so as to dislodge solid material from the radially inner surface of the drum wall, and an outlet for solid material located at the upper end of the drum, the scraping means being arranged to cause the transport of solid material dislodged from the drum upwards towards the outlet.

2. A separator according to claim 1, wherein the drum axis is substantially vertical.

3. A separator according to claim 1 or 2, wherein the scraping means comprises an auger radially outer edges of which act as scrapers to dislodge solid material from the drum wall, the auger being arranged such that dislodged solid material is carried to the solids outlet.

4. A separator according to claim 1, 2 or 3, wherein the scraping means is rotatable about the major axis of the drum, the scraping means being rotated at a different speed from the drum so as to maintain relative movement between the scraper and the drum.

5. A separator according to any preceding claim, wherein the scraping means supports brushes that bear against the radially inner surface of the drum wall.

6. A separator according to any preceding claim, comprising means for pumping slurry into a lower portion of the drum, the pumping means being connected to a lower portion of the drum and in use being dropped into a body of slurry.

7. A separator substantially as hereinbefore described with reference to the accompanying drawing.