Research On Control And Measurement Method For Blasting Fragmentation Of Deep Hole

Sandbank mine was used by Guizhou Phosphorite Limited Liability Company in order to satisfy development needs. The Phosphorite mining scale will reach1.5-2million tons per year with the transportation problem brought into as the first one in urgency to be solved. Now the mine uses scrapers-ore belt conveyor system to transport the mine rock from the bottom of medium deep hole to the earth surface. The size of rock mined is not uniform and the rate of large block is bigger, hence causing serious damage of belt, increasing the times and time of repair as well as laying-off. Furthermore it will decrease the transport capacity of belt, increase cost of transportation and affect the company’s mining capacity, which in turn hinders the company’s development and the increase of economic benefits. Therefore the reasonable block size in blasting is the key to realize the improvement of sandbank mining capacity.This study investigated the methods and technology to control block size in medium deep hole blasting in the following aspects:(1) The basic physical mechanical properties and stability parameters of mine rock were obtained through survey on site engineering geology and mechanical experiments of mine rock in lab. The blastability classification of sandbank mine rock was got by the application of unascertained average classification theory.(2) The large block was defined according to the study of belt transport system in the sandbank mine and the requirements of belt on materials size while transporting. The methods for measurement of large blocks were studied comparatively. The image processing technology, that was verified in application, was used to measure and count the large blocks in mine. The results proved that the measurements of large blocks by image processing technology were accurate and consistent with applications.(3) The range of blasting parameters was determined by the theoretical calculations and engineering analogy method, and the mechanism of pre-split blasting into a seam was investigated. The major parameters of pre-split blasting were obtained by theoretical formulas and numerical simulation, which offers theoretical references for the parameter selection of industrial blasting experiments in scene. (4) There were9orthogonal experiments designed by the orthogonal theory with row spacing, distance from the hole bottom and unit consumption of dynamite as factors and rate of large blocks as index. According to the results the best optional blasting parameters were obtained and blasting parameters in each grade were given based on the blastability classification of sandbank mine rock.(5) Finally the methods for processing residual large blocks were researched. Hydraulic gravel trolley was employed for the recrushing of residual large pieces after the analysis of fixed investment, security, production capacity and efficiency etc.