What is filter press?
The filter press is a machine used for solid liquid separation process. The main goals of the filter press technology is the slurry dewatering – sludge dewatering or slurry purification depends on application by application. The filter press has quite ancient origin but it is still a modern technology used on many important industrial and environmental application. The secret of the filter press’s historical life is the versatility and the reliability of this filtration technology. In fact the filter press is used from the sludge dewatering produced in the municipal water treatment plant to the gold production or the blood plasma purification. Of course today the filter press technology has been improved and developed a lot compared to the past thanks to the new technological materials and the automation systems.
How filter press works?
The filter press working principle consists, feeding the slurry by pumps inside many filtration chambers, where every filtration chamber of the filter press is made by two main filter elements called filter press plates and filter press cloths. The filter press plates and cloths retain the solid phase inside the filter press filtration chambers and allow the liquid phase to be discharged outside from the filter press filtration chamber.
When the filter press filtration chambers are full of solids the filter press filtration cycle is completed. Then the filter press open all the filtration chambers in order to discharge the dry Filtered cakes and to start a new filtration cycle. This filter press filtration cycle is valid if chamber plates are installed on the filter press. And in this case the filter press is called Chamber Filter Press.
Instead if on the filter press membrane plates are installed it is possible to have other filtration steps. And in that case the filter press is called membrane filter press.
When membrane plates are installed on the filter press it is possible to make filtration step like cake washing, cake drying and cake squeezing. These additional filtration steps improve the filter press dewatering performance.
In filter presses the complete filtration process can be managed by the filter press in fully automatic mode by a PLC or manually, which depends from the filter press model selected.
In different industrial sectors for which purposes Filter Presses are used ?
In the mining industry, filter press is applied for two main applications. One is mineral concentrate slurry dewatering to achieve a dryer filter cake in an easy and efficient way. Secondly in Mining, filter press is used for environment friendly management & disposal of mineral tailings. In the metallurgical & metal refining sectors, filter presses are used for polishing a slurry with a low concentration of solids.
Whereas in sectors such as quarry, tunnelling, construction, municipal waste water treatment, etc. filter presses are used for the filtration of sludge for an environment friendly disposal of tailings or other undesirable effluents generated from the process. Additionally in sectors such as Chemical & Petrochemical, filter presses are used for dewatering of process slurry for further processing or for dewatering of hazardous effluent sludges for safe and environment friendly disposal.
How different Filter Presses are selected ?
The selection of the type of Filter Press is been made in consideration to the input feed slurry characteristics & the desired performance parameters required from the Filter Press.
Additionally, in case a representative sample is available, a laboratory scale filtration test is conducted. During the filtration test, all the industrial duty feed conditions are simulated and multiple tests are performed. Based on the filtration test results, the optimum filtration parameters for the filter press are defined to reach the desired performance. Consequently the filter press design, capacity & model are finalised.