If the former, China Minmetals, is a large central enterprise headquartered in Beijing, it would be great. Highly recommended.
If it is the latter, Shanghai Minmetals, the address is in Zhabei District. It is a pure trading company, that is, acting as an agent for middlemen. It does not have its own factory, and cooperates with small private steel mills in China. The treatment is very average. You may have to travel a lot. Think about it.