PSA in Metal Casting

Metal Casting Industry has also understood the efficacy of the PSA technology. In a very critical operation of the metal casting process. PSA process is used for recovering 99.5% of the sulphur dioxide used in forming cold box molds. At present the sulphur dioxide is used only once and the process is quite wasteful in nature. The SO₂ is then totally discarded by purging the mold with dry air or nitrogen. Subsequently a caustic solution is used to scrub the effluent. Eventually it is flushed into a sewer or directed to a waste treatment facility.

Compare this to the new system based on Pressure Swing Adsorption, that do not have any requirement of regenerant. As a result it produces no waste streams either. Results have been found to be remarkably good. Recovery rates of around 99.5% for Sulphur Dioxide and 99.8% for carrier gas has been obtained. These rates have allowed its usage without further purification. The main operating cost here is with regard to the power consumption in evacuating the adsorbent vessels during blowdown, and maintenance of low pressure during purge. The main advantages of using the PSA based system includes reduced energy consumption, elimination of the need for caustic effluent and guaranteed returns within a year.

New sandcasting SO₂ recycling technology using a pressure swing adsorption system for gas recovery instead of a wasteful scrubber system: