The moderate and deep treatment of the oil in the rare-earth ammonium chloride waste water with oil-blankets and activated carbon were carred out to make the oil meet the standard of the water quality of the membrane.

Through gas webbing and adding the preoxidised acrylic fibre fabric into the web, then ma king use of the needle punching and hot rolling to stabilize the web, finally, the preoxidised acrylic fibre felt is obtained.