Vibratory screening apparatus for screening liquids

DETAILED DESCRIPTION OF DRAWINGS FIGS.
1 and 2 illustrate a basic embodiment of the invention.
This comprises a basket 10 which is vibrated by a rotating mass 12.
Spring mountings 14 and 16 allow the basket 10 to vibrate relative to a fixed frame (not shown) and relative to a stationary fluid reservoir 18 below the basket 10.
The reservoir 18 is mounted on a base 20 and includes a fluid outlet 22 at the lowest point.
Although not shown, valve means may be provided for controlling the rate of flow from the outlet 22.
Although described as a reservoir, tank 18 is essentially a discharge tank for funnelling the filtered mud away.
A header tank 24, which includes a weir 26 over which liquid can flow when it exceeds a given depth in the tank 24, is supplied with a liquid and solids mixture along an inlet pipe 28 and it is this mixture which overflows the weir 26 and spills into the basket 10.
The design of the interior of the basket is best understood from studying FIG.
2.
The floor of the basket is formed from a fine mesh screen 30 the greater area of which is flat and horizontal and which includes an inclined section 32 which leads up to a discharge edge 34 over which solid materials such as 36 obtained by the filtration process will be ejected in the direction of the arrow 38 on the vibration of the screen 30.
The liquid which drains through the fine mesh screen 30 is collected in the reservoir 18 the floor of which slopes at 40 and 42 towards a central low level 44.
The right hand end of the basket 10 as shown in FIG.
1 and 2 (which constitutes the rear of the basket) is a solid wall 46 and this constitutes a weir or dam so that a depth of liquid can accumulates on the screen 30 as denoted by 48.
In the embodiment shown, the throughflow of liquid and solid material into the header tank 24 must be controlled so that the depth of liquid 48 within the basket 10 is less than the height of the weir or dam 46.
To this end a level sensing switch 50 may be provided to sense when the level 48 reaches a given level within the basket so at that stage to either shut down the flow of liquid and solids through the inlet pipe 28 or to adjust the apparatus so as to increase the through-flow of liquid through the screen as by increasing the amplitude and/or frequency of the vibration of the basket