Alternative processes for sulfides(cont) The predominance diagram for the Cu-S-o system appears in the next slide and should be contrasted with that for ni shown earlier in the course. For Ni, which has a fairly high affinity for oxygen, the area of the predominance diagram where the metal exists is small. For copper it is quite large and it is possible to engineer the oxidation of copper sulfide to operate in the metal predominant region. We will return to copper smelting later. But first let's look at roastingAlternative processes for sulfides (cont). The predominance diagram for the Cu-S-O system appears in the next slide and should be contrasted with that for Ni shown earlier in the course. For Ni, which has a fairly high affinity for oxygen, the area of the predominance diagram where the metal exists is small. For copper it is quite large and it is possible to engineer the oxidation of copper sulfide to operate in the metal predominant region. We will return to copper smelting later. But first let’s look at roasting