A main trend in underground mining is the use of systems with bulk caving. In these systems, ore is broken down by means of deep boreholes or mine charges, either with or without compensation chambers. The coefficient of loosening of the cut ore is 1.15-1.65. Incorrect discharge conditions with small loosening coefficients lead to increased losses and impoverishment, which can be reduced by partial discharge. The amount of partial discharge of ore from the caved blocks is determined by the loosening parameters for maximum and minimum compensation volumes.The coefficient of loosening of the cut ore depends on the fragment size, the ftagment-size composition, and the volume of the compensation spaces. To determine the coefficient of loosening of the caved ore in a block we need to know the parameters of the block, the volume of bulk-caved ore, and the volume of the compensation workings in the block. In the calculations it is assumed that when the ore is caved its volume increases, but cannot exceed the volume of the caved block,where Vp is the volume of the caved pillars and blocks in cubic meters, V b is the volume of the block in cubic meters, ~'o is the density of the ore in the massif (i.e., before extraction) in tons per cubic meter, and 7o.c is the volume of the broken-up ore in tons per cubic meter.Dividing both sides of (1) by Yo.c, we get ~, ~--= uo, The volume of the block is found from the formulawhere Hp is the panel height in meters, M o is the thickness of the ore body in meters, M r is the thickness of the rock interseam inside the ore body, and L b is the width of the block along the strike, in meters.The volume of ore in the caved pillars is found as the difference between the volume of ore in the block and the volumes of ore in the room, undercut, and preparatory and opening-up workings,where V k is the volume of ore in the room in cubic meters, V u is the volume of ore in the undercut in cubic meters, Vp. c is the volume of ore in the preparatory and opening-up workings in cubic meters.VostNIGRI, Novokuznetsk.