P'ing-ting-shan

The shaft project No 7 of the Honan P'ing-ting-shan Colliery designed for an annual production capacity of 900,000 metric tons that went into production in August 1959 is more complex than the shaft No 3 of the Huai-nan Hsieh-chia-chi Colliery that went into production during the First Five Year Plan;…