There are 363 coking coal mines under 138 companies in Shanxi, Hebei, Shandong, Inner Mongolia, Shaanxi, Henan, Anhui and Guizhou, with total capacity at 678 Mtpa，The sample points currently include 54 primary coking coal enterprises with total capacity at 180 Mtpa, 24 gas coal enterprises at 176 Mtpa , 13 meagre coal and meagre lean coal enterprises at 97.8 Mtpa , 16 fat coal enterprises at 82.7 Mtpa, and 19 enterprises of 1/3 coking coal at 86.2 Mtpa.

We decide the number of sample mines in each province based on its production. Priority is given to private mines with higher degree of marketization, supplemented by state-owned or local mines. Due attention is also paid to the type of met coal produced in deciding the number of coal mines. Mines of same capacity and ownership will be chosen to substitute those mines that  undergo bankruptcy and regrouping. In this case, subscribers will be informed timely.