Alternative processes for sulfides are illustrated on the next slide. One possibility is to oxidize the sulfide to an oxide and then carbon or hydrogen can be used to reduce the oxide. This works fine for metals that have a high affinity for oxygen(i.e metals about half-way down the ellingham diagram for oxides, or lower, zinc is a good example) and is carried out in an operation known as" roasting,. An alternative route can be used for metals with a lower affinity for oxygen(e.g copper); this alternative relies on oxidizing the sulfide to metal(rather than oxide)and is known as smeltingAlternative processes for sulfides.... …are illustrated on the next slide. One possibility is to oxidize the sulfide to an oxide and then carbon or hydrogen can be used to reduce the oxide. This works fine for metals that have a high affinity for oxygen (i.e metals about half-way down the Ellingham diagram for oxides, or lower, zinc is a good example) and is carried out in an operation known as “roasting”. An alternative route can be used for metals with a lower affinity for oxygen (e.g copper); this alternative relies on oxidizing the sulfide to metal (rather than oxide) and is known as “smelting