Zambian President Rupiah Banda opened the country's largest coal mine Friday, after Singapore's Nava Bharat took over majority shares and invested $750 million (525 million euros) at the once defunct state entity. Nava Bharat, a Singapore subsidiary of India's Nava Bharat Ventures, has a 65 percent stake in Maamba Collieries, with Zambia's government owning 25 percent through its Zambia Copper Mines Investment Holdings.