^pof;
Mines,;
China;
University;
of;
Mining;
&;
Technology,;
Xuzhou;
221116,;
China;
^pKey;
Laboratory;
of;
Coal;
Resource;
and;
Mine;
Safety,;
Xuzhou;
221008,;
China;
^pCoal;
Mine,;
Shenhuo;
Group,;
Yongcheng;
476600,;
China;