is wolfram profitable the answer is no, page-26

The (tri)oxide is used for pricing. QOL produces the (di)sulphide which is subsequently roasted to form the oxide. The sulphide contains 11% less Mo than the oxide which is reflected in the offtake agreement with CITIC, along with a roasting adjustment. As to why QOL don't roast themselves - it's all about scale and having a ready use for the sulphur dioxide that is produced - not much demand in their part of the world.