It says nothing about "purifying the soul"
It says that inferior material like hay and stubble "burn, he shall suffer loss; but he himself shall be saved, yet so as by fire". The allegory is of a house (verse 9) that has good material and bad material in it and through fire only the good material remains, i.e. the house is purified.
Dude, if part of the house is burned it ain’t saved! Catholic analogies are so off base it’s actually comical.