INCREASING LIMESTONE LUMP RATE BY BOTTOM BROKEN CHARGE BLASTING

Increasing limestone lump rate by blasting is one of research tasks all along. Based on the blasting diagnosis at Xigou Limestone Mine of Jiuquan Iron & Steel Co., this paper points out that at present problems in bench deep-hole blasting limestone open-pit mine everywherel describes the blasting principles for increasing limestone lump rate by bottom broken charge blasting technology. The test of small-scale bench model made from cement grout had been produced. The bottom broken charge blasting technology was used in Xigou Limestone Mine and the little overdepth (or not overdepth blasting) was realized. By this way, the single-hole sequience igniting was gone so that the squeeing action between ore and rock was decreased, the limestone lump rate was increased and the powder factor was decreased.