REACTION OF DROSS FORMATION IN CONTINUOUS GALVANIZING.

Abstract

The effect of the Al content of galvanizing baths on dross formation was investigated. The results of spectroscopic and quantitative microscopic analyses show that drosses contain two compounds, delta and Fe//2Al//5. When the Al content of the bath is between 0. 09 and 0. 14%, delta and Fe//2Al//5 can coexist. In this case, the higher the Al, the lower the fraction of delta compound. With more than 0. 15% Al, no delta compound is found. The amount of the bottom dross is estimated to decrease rapidly with increasing Al content in the bath up to 0. 14% and becomes negligible above 0. 15% Al. The amount of the top dross, however, increases rapidly with increase of Al to 0. 14% and decreases gradually above 0. 15% Al. The amount of aluminum consumed in the dross formation reaction is estimated to be proportional to the iron dissolved from the sheets being galvanized.