The single-stage filtration method has its own advantages and limitations in terms of CFF filtration mechanism, filter size, filtration efficiency, life and cost of use. The use of multi-stage combined filtration methods can make up for their own shortcomings while playing the advantages of single-stage filtration. Application forms include filter combinations with the same filtration method and different filtration stages: the combination of different filtration methods; the development of pore gradient filters, and the combination of filtration and other purification methods.
For example, the CFF filtration mechanism with large and small pores is placed at the front and back of the filter to form a two-stage filter to prevent large particle inclusions from blocking the small pore filter, and the filtration efficiency is about 15% higher than that of single-stage filtration. There are currently 3050pp, 3060ppi, 3070ppi and other combinations. It can also be used in conjunction with 30~50pp CFF and particle combined tubular filters with different pore sizes, and the filtration efficiency can be increased by 20~30%.
Among the filters currently used, the deep bed filter and the ceramic particle combined filter have the highest service life. During the two replacement of the filter medium, it can process hundreds to thousands of tons of aluminum melt, and can be used continuously for several weeks or even several. However, the cost is high, the replacement (or cleaning) of the filter medium takes a long time, and the cost of intermittent melt insulation is high, so it is only suitable for high-grade, large-scale melt filtration. For the filtration of small and medium batches of aluminum melt, the most economical and effective filtration method is CFF, but CFF is currently produced by the organic foam impregnation method.
AdTech ceramic foam filter plate uses a three-dimensional network structure and organic foam with connected pores as a carrier, which invades the thixotropic special molten material slurry, and adopts a four-square correction center distance automatic extrusion process to make the slurry uniform It is applied to the foam skeleton of the carrier and baked at high temperature after drying and curing.