coal rank index的用法和样例：
- It seems reasonable to assume that the organic affinity of trace elements decreases with the coal rank incr...
- The necessity of expanded coal rank for CWM production and saving coking coal resources were discussed in this paper.
- Powder River basin, Uinta basin of USA and Tiefa basin of China are all low coal rank basins.
- Coal matrixflexibility energy decreased with the increasing of buried deepness of coal reservoir, and increased with the rising of coal rank.
- The influences of coal rank,ope-rating conditions and mineral matter in coal on phenol adsorption of the active car-bons have been investigated.