‘LaSapienza’,Rome,ItalybCollegeChemistry,PekingUniversity,Peking,ChinaReceived16February1999;receivedinrevisedform15November1999;accepted22November1999AbstractRecently,therequirementofdevelopingtheautomaticcontrolforrareearthextractionprocesseshasbeenattractingalotofattention.However,duetothesimilarityofchemicalphysical...