DEVELOPMENT OF BLASTING DESIGNS FOR UNDERGROUND MINING IN THE KAULDY MINE OF ALMALYK MINING AND METALLURGICAL COMPANY

Abstract

The implemented analysis of the perimeter control blast designs in the Kauldy Mine of Almalyk MMC shows that the method efficiency depends on the correct selection of a spacing between perimeter blastholes, ratio of the blasthole spacing to the burden relative to the buffer blast row and a volume ratio of explosive charge and blasthole. The experimental procedure of the perimeter control blasting design in underground mining is developed. The procedure made is possible to estimate the influence exerted on the perimeter control blasting efficiency by: shattering force and strength of explosives, spacing of the perimeter blastholes, closeness factor of the blastholes, charge design, incline angles of the perimeter blastholes and geological structure of the ambient environment. An ‘effective stemming’ technique is proposed as blasting of an additional shortened blasthole to make a face cut in treated rock mass. The varying density stemming generated by blasting an additional inclined and shortened blasthole increases burning of blastholes by 2 times. From the hydrodynamic theory of cumulation of explosive effect, the depth of breaking in rock mass is determined as function of the cumulative jet length and density, density of rocks as well as compressibility of rocks and the jet material. The studies show that efficient rock fragmentation by blasting with cumulation of explosive effect is achieved by means of changing the angle of implosion of cumulative liner, dependent on the initial/final velocity ratio of the cumulative jet, the time of the jet action on rocks, as well as the height and thickness of the cumulative liner. Adjustment of the implosion angle can reduce the yield of oversize by 1.2 times. The method of rock breaking by blasthole charges with cumulation of explosive effect is developed and tested on a full scale in underground mining. The method allows enlarging the blasting pattern effect owing to the complete use of explosion energy, increasing the utilization factor of blastholes, decreasing the powder factor and, thereby, cutting down the expenses connected with drilling and blasting in underground mining by 20%. The perimeter control blasting design is developed for underground mining, and a set of interrelated parameters which govern the blasting performance at the perimeter of mine roadways is determined, including the spacing of blastholes, the charging ratio, the closeness ratio and the delay of electric detonators in the perimeter blastholes.