SINGAPORE, March 4 (Reuters) – Jiangxi Copper , one of China’s top copper producers, said on Monday it planned to buy a nearly 30 percent stake in the Shandong smelter for 2.98 billion yuan ($444.83 million) to become its controlling stakeholder. The Shandong smelter has a capacity to produce 50 tonnes of gold, 1,200 tonnes of silver and 250,000 tonnes of refined copper annually, Jiangxi Copper said in a stock filing.  The transaction is pending approval from the state asset watchdog, the firm said.