PASTE & TAILINGS 2021 devices and are commonly used in aggregate and mineral processing waste slurry applications . Typical recessed plate filter presses are composed of a heavy-duty support framework holding a series of polypropylene plates with concave surfaces on each side of the plate . Each plate is lined with a synthetic filter cloth . The plates are tightly clamped together with hydraulic pressure , creating a void space between the plate surfaces .
A high-pressure slurry feed pump is used to force slurry material into the void spaces between the plates . The slurry solids are captured between the plates , while the liquid passes through the filter cloths mounted on the plate surfaces . When no additional slurry can be pumped into the filter press , the slurry feed pump is stopped and the plates are separated , allowing the cakes to fall by gravity out of the press . The up-front investment for a plate filter press can be high due the size of the equipment and required support structure .
Depending on the type and amount of material being dewatered , modern filter press equipment can be very big and require a large space for installation and operation . Common polypropylene plate sizes today can be up to 8 ft wide by 8 ft tall , with large filter presses holding up to 200 plates .
Plate filter press operating costs are low due to the requirement of only a part-time operator , lower wear parts cost and typically no need for chemical dewatering aids . Because the slurry material is captured completely between the filter plates , very high dewatering pressures ( up to 225 psi or higher ) can be applied to the slurry . The high dewatering pressures produce the highest cake solids concentration possible of any mechanical dewatering equipment .
Plate filter presses can also employ a second type of plate called a membrane plate . In this case , the plate has a flexible membrane surface made from polypropylene or other synthetic flexible material such as hard rubber . The membrane can be thermally fused to the concave plate core , or the synthetic membrane ’ s
edge can be embedded into the concave plate core in a small channel machined in the plate surfaces . The same initial process is used in a membrane plate press , with a high-pressure slurry pump feeding the press to fill and dewater as much slurry as possible .
After the slurry feed pump is stopped and while the filter plates are still clamped together , the membrane surfaces are expanded using compressed air or water . This inflated membrane compresses the cake
material , removing additional moisture to the lowest possible levels .
Plate filter press advantages
No other dewatering process has shown to be more efficient at removing liquid from slurries as the plate filter press . Additional benefits of plate filter presses include : n Highest amount of recovered water n Driest cakes n Lowest operating cost n Lower waste handling cost , haul less water n Most stable solid material generated
Because of these advantages and the high efficiency of the plate filter press , it is the best choice of equipment to eliminate settling ponds . IM
JULY 2021 | International Mining SUPPLEMENT P5