Abstract:In order to study the change of blasting quality and ore waste mixing condition along the depth direction in large volume buffer blasting of complex ore-body. A site test has been done in a large open-pit uranium mine in Africa. The height of the blasting steps is 7.5 meters, with 18 rows of holes, and the blasting capacity is 350 000 tons. The trial found that the blasted heap close to the buffer (loose area) was superior to the blasted heap far from the buffer (dense area) in terms of heave height, rock mass fragmentation distribution, and shovel efficiency. It is revealed that the blasting effect of large volume buffer blasting decreases along the direction of depth. After blasting, the ore quantity in the test block increased by 14.6%, grade decreased by 4%, and waste rock amount dropped by 28.84%, the ore waste mixing is more obvious in loose areas and the ore rock quantity increased, in contrast, the ore rock quantity in the dense area reduced. To improve the blasting effect in a dense area, one blasting block and two blasting parameter strategies are proposed.