Midwest shares colsed up 31%, or $1.28, at $5.43. Sinosteel, a steel commodities trader, already owns 19.9% of Midwest and is a joint venture partner in Midwest's Mt Weld prospect, one of the Australian firm's five projects. Sinosteel is offering around $954 million for the remaining shares, based on shares on issue. It said it has already received Australian Foreign Investment Review Board approval for the bid. China, with its bustling economy, has emerged as the world's top steel maker with a growing appetite for imported ore to feed its mills. ''Iron ore prices are rising fast and it's in the best interest of Chinese companies to get into companies like Midwest as soon as possible,'' Wilson said. The offer hinges on a minimum 50.1% acceptance and Sinosteel receiving Chinese regulatory approvals.