China, one of the world's largest coal producers, is to close some 22,000 mines by 2000 in a bold move to restructure an industry hit by chronic oversupply nad weakening demand. The plan, reported by the official media yesterday, provides a disturbing insight into the extent of China's economic slowdown.Coal contributes about 75 per cent of its energy needs, but outoput fell 7.8 per cent to 539.7m tonnes in the first hlaf of the year compared with the same period a year ago.