Study on Ore Loss and Dilution Control based on Blast Movement Monitoring System

To reduce the loss and dilution of ore in Husab Mine, a blasting movement monitoring(BMM) system was introduced and tested in three production blocks with 177 mm diameter drilling holes and a 7.5 m step height. During the field test, 6, 8, and 5 monitoring holes were arranged in each test block. Two displacement monitoring balls were placed in each monitoring hole at a 3.5 m and 9m depth to record the rock body's vertical and horizontal movement after blasting. The results show that the movement of the ore body due to blasting can be detected by BMM, and the average horizontal displacement of the upper ore body of the three test blocks is 6.55 m, 6.97 m, and 9.24 m, respectively. The average horizontal displacement of the lower ore body is 3.2 m, 3.9 m, and 4.0 m, respectively. The average vertical displacement of the upper ore body is 4.1 m, 2.0 m, and 3.2 m, respectively. The average vertical displacement of the bottom ore body is 0.72 m, 0.98 m, and 0.84 m, respectively. The ore body always moves in the direction with the least resistance during blasting. Whether horizontal or vertical displacement, the displacement of the upper ore body is always more significant than that of the lower ore body. In addition to changes in the boundaries between the ore and rock due to horizontal displacement, vertical displacement also has a significant influence on the loss and dilution of ore, and the bottom ore body may also move to the middle or the upper part of the ore body, and vice versa. The blast zone of open pit mines often consists of a variety of rocks, and both horizontal and vertical displacements of the ore body after completing the blast design based on geological information are the leading causes of ore grade reduction. Using the post-blast rock boundaries obtained from the BMM system monitoring to guide the excavation and transportation operations, the average ore dilution rate has been reduced by 1.2%. The average loss rate has been reduced by 1.5%, which can create more than 10 million RMB of economic benefits cumulatively over the entire life of the Husab Uranium Mine. This technology can accurately define the ore-rock boundary after blasts, which is an important technical means to reduce the ore dilution rate, ore loss rate and ore grade classification errors in open pit mines.