| Customization: | Available |
|---|---|
| Feature: | Long Time Materials |
| Refractoriness (℃): | 1000 |
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A deep-bed filtration system is used to clean metal prior to casting and can achieve filtration efficiency of greater than 90 percent. These systems are frequently used in slab rolling ingot and continuous sheet casting processes. It typically is placed in between the holding furnace and the casting operation and consists of an outer steel shell with a refractory lining containing grid plates and layers of alumina balls. Alumina balls are the primary filter media for deep bed filtration systems and the size, shape, packing pattern and depth of the media can be varied to achieve desired filtration performance. Due to its high filtration efficiency, the deep-bed filter is commonly used in operations that require especially critical product quality such as can end stock and lithographic sheet.
Boxes/Liners
We supply the necessary design, engineering and manufacturing expertise to build a Liner Systems that will conform to the specific assembly desired. Any size, shape or configuration is possible for a turnkey solution.
Baffles and Dams
Precision-cast baffles for the molten metal casting process are avaiable
Calcium Silicate Grid Bars
Defined as an elevated platform in a bed filter to support the filter media and allow metal flow. Custom designed and engineered for each individual specification with tight tolerances.
Floats
No Outgasing, Custom engineered shapes to meet any requirement, tight tolerance, and Low density and fused silica refractory options.
Bed filters (BF) are bulks built of Al2O3-balls or chips with a size of 2 - 8 mm. Bulks of carbon or coke are not used anymore. BF´s are separate in-line units, which need rather much space. They are built in externally heated boxes and are suited for the throughput of large amounts of melts up to 1000 t. Particle form and size, layer thickness, and the sequence of different layers are varied to improve the filtration effectiveness. BP filters are suited for the separation of small inclusions < 20 μm from melts with low inclusion concentrations. Ceramic foam filters (CFF) consist of a labyrintic structured ceramic material in which a very effective cleaning of the Aluminium melt happens by deep bed filtration effects. They are produced by the infiltration of a ceramic sludge into porous polyurethane foam. During firing the plastics decomposes and the porous ceramic remains. CFF are also built in separate boxes, which must not be heated externally. Filter plates are commercial available in different sizes, thicknesses (normally 50 mm) and pore sizes between 10 ppi to 80 ppi (pores per inch). They are one-way products and rather cheep so that the operational costs are low. This filter type is used most often in Aluminium metallurgy. Rigid media filters (RMF) consist of porous ceramic tubes, which are built in like BF´s in external heated boxes in form of pipe bundles. The melt flows from the outside to the inside of the pipes. The filtration processes are very similar to the CFF´s. Because they have a smaller pore size there is a greater pressure drop and they have a shorter lifetime. RMF´s are rather expensive in respect to investment and operation cost, therefore their application is limited to special applications. State of the art is the application of deep bed filtration in foundries, where large amounts of the same alloy have to be cleaned. For general purposes CFF´s are used. Only for special applications RMF´s are in operation because they are most efficient for the removal of very small particles. In normal filter systems single CFF plates or combination of CFF´s with different pore sizes are built in in separate boxes which must not be heated externally. They are positioned in-line directly before the DC unit. The melt is allowed to run through the filter plate, mostly downwards. CFF´s are used in combination with BF´s and with degassing units, too. Additional ceramic filter clothes may be used at the DC casting unit to retain coarse impurities which can enter the melt after filtration. Targets for the filter development in the future are filters that can remove even finer particles with high efficiency at a reasonable pressure drop and with minimized metal losses.
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