Effect Assessment of Buffer Blasting with Multi-row Holes and Large Block in Husab Open-pit Uranium Mine

In order to solve the problems of large displacement, high boulder yield and low shovel loading efficiency in the front row of Husab mine blasting operations, a series of buffer blasting trials were designed and conducted. The project has successively completed the buffer blasting tests in 5 large blocks, and each section has 360 000 tons to 530 000 tons of ores, 15~21 rows of holes, and 5~40 meters wide buffer materials on the free surface. The muck pile shape, shovel productivity, fragmentation and floor elevation deviation were measured and compared with the non-buffer blasting results in the same period. The test results show that there are forward pounce and uplift phenomenon to the blasting pile under the impact of explosion. Meanwhile, the muck pile surface presents a shape with unequal heights, and the maximum height difference varies from 4.06 m to 5.85 m. The productivity of a hydraulic shovel is 2722 t/h in the buffer blasting blocks, which is 4.69% higher than that in the non-buffer blasting blocks in the same period. Moreover, the results of fragmentation analysis reveal that the buffer blasting is better than non-buffer blasting on the fragmentation performance, and the buffer blasting has the advantage in reducing boulders. Finally, the test results show that the buffer blasting has certain advantages in floor elevation control. It is the first time to promote buffer blasting technology to the blasting of large sections with multiple rows of holes(15 to 21 rows), which is not only in line with the objective needs of large-scale mine production, but also an inevitable trend as large-scale equipment is used.