Abstract: Filter press apparatus comprises a plurality of substantially parallel filter plates assembled as a unit and located within a substantially rigid outer shell to provide a closed vessel to which can be supplied medium under pressure to be filtered via the plates, a substantially impermeable primary membrane lining the shell for forming a substantially incompressible boundary wall to the unit on supply of pressure medium to the space between the primary membrane and the shell, and a secondary membrane having an intermediate extent between the primary membrane and the unit which, with the primary membrane urged towards the unit, moves axially with the unit and slides relative to the primary membrane to eliminate stress in the primary membrane during the compression stage.

Abstract: An endless belt filter for separating liquids and solids from a mixture comprises a liquid-permeable filter belt below the upper run of which is positioned at least one suction tray moveable in the direction of the upper run of the belt, at least one hollow, elongate vacuum rail below the suction trays extending the length of the upper run of the belt, the suction trays seating on the vacuum rail to be guided thereby in their longitudinal movement therealong, and a vacuum source connected to the hollow interior of the vacuum rail, the trays including one or more apertures communicating into the hollow interior of the vacuum rail whereby an under pressure is applied to the trays by the vacuum source to draw liquid from the trays into the vacuum rail. The trays are supported by a pneumatic cushion.

Abstract: A method of producing a gel material and which comprises firstly providing an aqueous soluble hemicellulosic starting medium which is free of glucans and obtainable from testaceous plant material. The starting medium is then extracted with a non-acidic reagent and reacted with an oxidizing system comprising at least one peroxide, together with at least one oxygenase (such as a peroxidase).A gel material which is obtainable from a hemicellulosic starting medium, and which is substantially free of glucans and pectins. The gel material comprises a polysaccharide network for a matrix of polysaccharide chain segments and a multiplicity of cross-linking ferulate bridges. The ferulate bridges are located at regular intervals along the cross-linked segments.

Abstract: A method of separating solid particles from a mixture of solid and liquid components comprises filtering the mixture to provide a damp filter cake and adding a liquid densification aid to the filter cake to promote densification of the cake. The method is useful for separation of inorganic, generally crystalline, materials from aqueous slurries, for example. Suitable densification aids are flocculating agents such as solutions of alginates and gelatin, and surface active agents. The densification aids promote closer packing of solid particles in the filter cake and assist removal of residual liquid component trapped in interstices between particles.

Abstract: A plurality of substantially parallel filter plates are assembled as a unit and are locatable within a substantially rigid outer shell to provide a closed vessel. Either or both of the unit and the shell are movable relative to the other between a position wherein the unit is sealed within the shell to enable pressurised supply to the shell of medium to be filtered via the plates and a position wherein the unit is at least partially removed from the shell to enable discharge of resultant filter cake from the plates. To improve filter efficiency, reducing the number of plates required and the pressure required, and to allow the removal of the filter plate unit when encrusted with filter cake, substantially impermeable, flexible membrane is provided as a lining to the shell and an additional shell inlet/outlet port is provided and is connected to pressure medium supply means so that a space between the lining and the shell is inflatable by pressure medium for the duration of the filtration operation.

Abstract: In order to wash the lower run of a horizontal belt filter more effectively, and simultaneously provide for tensioning of the lower run, as required when progressing the belt intermittently, a dead weight roller is supported in a bight of the lower run of the filter belt and reciprocates up and down in a wash liquor vessel as a drive roller is alternately extended, so as to advance the upper run of the belt, and retracted. A one way device is located upstream of the dead weight roller to prevent backward movement of lower run. As the bight decreases and increases, rolling action of the dead weight roller rubs the belt and forces wash liquor therethrough. A plurality of dead weight rollers in one or more wash liquor vessels may be provided and they may be guided at their ends in vertical or oblique guide tracks.

Abstract: In horizontal belt filter apparatus wherein the belt is progressed by alternate incremental motion of the upper run and the lower run, wash liquor used for washing the belt in the lower run, e.g. by spraying into a wash box, is recycled and used for washing filter cake on the upper run at several spaced apart locations. Also, in the upper run, a respective compression device is arranged subsequent to each supply of wash liquor in the direction of travel of the upper run, and during compression gas is blown into the filter cake through the pressure plate of each device so as to maximise extraction of liquid. Trays mounted below the belt are connected to vacuum during stationary periods of the upper run and are arranged to ensure separate collection of liquid for successive sections of the upper run, which liquid may optionally be recycled to upstream locations.

Abstract: Batch filtration is carried out within a rockable/rotatable housing, suspension to be filtered being fed in via ports in the upper region onto a curved filter fixed within the housing, and filtrate draining from below, via outlets to which vacuum may be applied. The housing is preferably cylindrical and may be mounted upon rollers or wheels so that rocking or rotating can be effected by belts or chains attached between the housing and a linearly reciprocable member, or by a rotary gear or friction drive wheel acting on the housing circumference, or by rack and pinion means, or a variety of other means. Washing of filter cake, reslurrying, drying by hot gases, and pressurization can all take place "in situ" whilst rocking continues, and discharge of cake is effected via the same ports as for inlet by turning the housing over.

Abstract: The invention provides an improved web guidance mechanism in which the location of a web is detected and any deviation from a desired path is corrected without causing damage to the web material, for example a filter cloth. The improved mechanism includes two tracker units 10 having a pair of rollers 12, 14 defining a nip for an edge margin of a web. The lower roller 14 is acted on by an inflatable actuator 28 in the form of bellows and operative to raise or lower the roller 14 with respect to the upper roller 12. This is achieved by pivotally mounting a bracket 16, which carries the roller 14, and attaching thereto a bar 24 which rests via a contact plate 26 on the actuator 28. The actuator 28 is controlled by a sensor positioned adjacent to an edge of the web and operative to detect the presence or absence of the edge of the web on its desired path. In a preferred embodiment the sensor controls a pneumatic valve operable to inflate or deflate the actuator 28.

Abstract: In a vacuum belt filter, in order to allow for additional washing of filter cake, a plate is mounted in an inclined disposition above the upper run of the belt with its lower end directed upstream so that as the belt is progressed filter cake moves up over said plate. At the top of the plate, the cake drops into a receptacle and is washed and reslurried by liquid from jets before being returned to the belt downstream, preferably immediately below, the inclined plate. As an alternative to immediate return to the belt, reslurried cake may be transported from the receptacle to a reservoir for further washing or prolonged leaching before it is returned.

Abstract: Subsequent to formation of a filter cake upon the surface of belt and further vacuum filtration (via vacuum trays), the cake passed below and is covered by an impervious sheet, and is dried by application of radiation, e.g. microwaves, radio waves, through the sheet, along with further evacuation (via vacuum trays) below the sheet. Because the cake is under suction pressure, the evaporation temperature of the filtrate is lowered to a level which will not adversely affect the cake, and which can be reached very rapidly by application of this form of radiation.

Abstract: A double valve arrangement is installed in intermittently operating vacuum filter apparatus in a pipeline connecting the filter means to a vacuum source to vent the line to atmosphere whenever the vacuum is shut off. This valve arrangement comprises a pipe section provided with a lateral opening, connected to the filter means, and with internal mutually facing annular shoulders disposed at respective sides of the lateral opening, and a piston-mounted sealing disc which is of smaller diameter than the pipe section and is reciprocable inside same to abut sealingly the one or the other of the shoulders and thereby bring the lateral opening into communication with the respective opposing end of the pipe section, which is connected, respectively, either to the vacuum source or to atmosphere. An annular gap is always present between the peripherly of the disc and the internal surface of the pipe section so that movement of the disc, e.g. at a frequency of 5 to 20 cycles per minute, is not impeded by rubbing.