Processing

Solid liquid separation in a filter press is related to the nature of the suspension, type of feed pump and its pressure, as well as types of solids. Generally seen is the highest filtration rate during low pressure and highest dewatering capacity during the higher pressure out from the press.

The characters of the solid are important factors such as size, form, types etc. By understanding those conditions in combination with other demands for temperature, organic/inorganic suspensions, ph factors and so on, it is mostly possible to get a successful result. The press is a tool which needs to be integrated in the process. For this purpose it is necessary to understand how to select the processing components adapted to the conditions for the press as well as optimizing the results desired.

Modern processing of suspensions is today focused on upstream processes where recovery of liquids or solids is required. Traditional technology where feed pumps are used for all requirements is normally not suitable and instead needs to be applied in stages: 

Solid treatment stage

This stage allows for a high-efficiency flow out from the press as well as allowing for the possibility of washing out the mother liquid from the collected solids This is used in the pigment production or in sugar factories for example. Cross flow washing or center feed washing are
technologies used in the press to move out the liquid as well as polishing the particles.

Dewatering stage

As more solids collect in the chamber less filtrate comes out. It is now possible to meet the demands of both high flow and high concentrate of solids in the cake where the conditions could meet the demands for the membrane press technology. This depends on the conditions and related to concentration of solids in the suspension and lowest demands for flow capacity.

Most common in the metallurgical industries is to wash down the cake for other leaching steps or if possible to feed as much solids into the chamber system allowing the moisture to squeeze out.