Technology of block caving systems in ore mining

Abstract

A recent development In the technology of ore mining is block caving using deep boreholes. In block caving systems an important stage is the last operation -discharge of ore from the caved blocks. Its efficiency depends on varlous geological, constructional, technological, and organizational factors.In the new technology the technological block (the system of working with the above factors) is the object of control. Its Input parameters are the geological conditions under whtch the deposit Is worked, the constructional data of the system of working, the technological parameters, the organization of all types of operations In the block, etc.Since the mode of occurrence of the ore bodies varies over the deposit but is constant within a single block, we must solve the problem of managing the technology of underground working separately for each block.The parameters governing the effectiveness of an underground working system are the width of the compensation slots (rooms), the length of a block to the strike, the distance between the ore discharge workings, their crosssectional areas, the blasting parameters and the amount of explosive expended on breaking down ore, the standard fragment size of the ore discharge from the block, and the minimum metal content of the discharge batch at the moment of cessation of recovery of ore from the block.Any changes in these parameters will influence the efficiency of fiae mining undertaking,The result of control of the technology should be a combination of control factors which wfll ensure continuous ore discharge wtth minimum cost of winning and of production of commercial products and which will give high output per man-shfft tn discharge of ore from the blocks and will cut down the numbers of blocks in various stages of development and extraction operations.Below we give the main mathematical relations In an algorithm for controlling the technology of underground working systems with block caving. Control of Movement of Caved Ore in the Worked-Out AreaFree flow of ore from a block Is governed by the area of the block, the loosening and fragmentation quality of the ore, and the cross sectton of the discharge workings. The problem of controlling the movement of caved ore in the worked-out area Involves such Important factors as the width of the compensation slots (rooms), on which depends the degree of loosening of the ore, the blasting parameters which determine the fragment size of the brokendown ore, and the necessary cross section of the discharge workings.With uniform discharge sequence the minimum permissible coefficient of loosening (bulk expansion) of the ore in the block for which Its movement in the caved mass wtll occur without hanging and arch formation will be given by the formula ~mt. = ~e~ 1,77--0.0264-Mo+0,00026.MoL Institute of Mining, Siberian Branch, Academy of Sciences of the USSR, Novostblrsk.