Why are the trade unions of Coal India planning to go on a strike across India?

Trade unions of Coal India Ltd are planning to go on a 3-day strike from July 2. This is in protest against the government's move to open the coal sector to private players. This could be an overhang as government plans to launch commercial coal mining this week. Trade Unions have sent a draft strike notice to the government. The unions are demanding to stop auction of coal blocks for commercial mining and ensure payment of high-power committee wages to contractor workers.