Its prominent character was high oil content and resistant to cyst nematode.

Recently,the practice improved that using technique of wide-space small burden blasting can improve the rock crushing,low the big crushing rock rate,reduce the secondary crushing cost.

The holes pattern of wide space,small burden in 4.

Large holespacing and small burden blast can enlarge the angle of crater, produce an arc free face beneficial to the intensification of reflecting tensile stress and the distribution of velocity field, and enhance the utilization of blasting energy and improve blast efficiency.

Six causes were analyzed, which are connected with toes after blasting: including geological condition, insufficience in terms of plugging length, burden, charge quantity and subdrilling, and unreasonable initiation technology.

Determination of heading wall s reasonable resistance line in the case of short delay blasting;

The paper had set up the related parameters of the loose blasting with the loose blasting circle, approximated equivalent resistance line and gray decision theory Those related parameters applied to Majiagou Mine of Kailuan were obtained with obvious economic benefits The successful experience of the technology has a certain reference to the mines with the caving mining production