The slurry feed can either be controlled by a feed valve/level sensor or can be set at a standard rate (if the slurry composition, vacuum and cloth condition remain constant then so will the throughput) with a weir overflow sending surplus slurry back to the feed tank.Ĭake formation and filtration occur during the time that the sector spends in the trough. The slurry is normally fed directly into the slurry trough. In some cases an agitator system may be needed.
The larger surface area rotating through the trough (compared to a drum filter of similar overall size) means that the slurry is more highly agitated by the filter itself. This trough may be partly compartmentalized in order to reduce the volume held in it at any one time (and therefore reduce the residence time of slurry in the trough). The barrel is supported on bearings and may be either directly driven by a motor or indirectly through a gearbox. A number of discs can be fitted to the same central barrel. Each sector is connected to the control plate by individual pipes (or hoses) or through fabricated channels in the central barrel to form a disc. The filter cloth is usually supplied as a cone, which is fitted over the sector and sealed top and bottom. Cake discharge usually occurs at atmospheric pressure via a scraper blade.įigure 4.25. Both cake deliquoring by gas blowing and displacement washing, can be performed reasonably effectively at different pressures through a multi-compartment arrangement within the housing. Raised temperatures can be accommodated as can volatile and toxic feeds. Rather than applying a vacuum inside the compartments of the drum, the pressure inside the housing is raised by compressed gas up to 800 kPa and this facilitates constant pressure filtration at the outer drum surfaces. It comprises a rotating, bottom-fed drum of area up to 120 m 2 enclosed within a sealed housing. The rotary pressure drum filter is similar in principle and basic form to the rotary vacuum drum filter (see Section 1.4.1.5). Typical particle size and feed concentration range: 1–100 μm and 5–30+% w/w. Typical uses: Continuous separation of finer particle suspensions where cakes require post treatment. Wakeman, in Solid/Liquid Separation, 2007 Rotary pressure drum
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