Not to play with words but is your scrap 99.96% pure copper scrap or is your copper scrap 99.96 pure copper?
From copper.com:
The copper anodes are then refined electrolytically to 99.9% purity. Copper melted under non oxidizing conditions is called oxygen free copper. The most popular form of pure copper is the standard electrical wire grade of copper (C11000) contains 99.95% Cu, 0.03% O2, and less than 50 ppm metallic impurities. It has a high electrical conductivity, in excess of 100% IACS. In the as cast form it is called electrolytic tough pitch (ETP) copper. The structure of the as-cast material is similar to that described above.