Solution: 

a)

b) % gangue is 85.21

c)

Formula is

If a copper ore containing 34% chalcopyrite,  and  is fused down and only excess sulphur is eliminated, what would be the matte grade?

References

1. Ray, H.S; Sridhar, R and Abraham, K.P: Extraction of non ferrous metals.
2. Rosenquist : Principles of extractive metallurgy
3. Butts, Allison: Metallurgical Problems, McGraw Hill Book Company, 1943