* $5.9 bln Tampakan copper project stalled over ban * Philippines is top nickel ore supplier to China (Adds more comments, background) MANILA, May 20 (Reuters) - The head of the Philippines’ Mines and Geosciences Bureau (MGB) on Thursday told Reuters he expected a ban on open-pit mining to be lifted soon, following a government decision to welcome new mining agreements after a long moratorium. The government imposed the open-pit ban in 2017, when the environment and natural resources ministry, which oversees mining, was led by an anti-mining advocate who had blamed the sector for extensive environmental damage. “I can’t speculate, but I hope soon,” said Wilfredo Moncano, whose bureau comes under the environment ministry.