Method of stowing a worked-out space

Abstract

method of mining economic minerals. In developing previously presented studies of the dense packing method for a worked-out space with barren rock [2] the present article considers a method for stowing long small-diameter tunnels. This method is based on the fact that the stowing material 1 (Fig. 1) is placed in a closed sealed channel 2. The mouth of the channel is covered with a sealed diaphragm 3 and compressed gas is supplied to its inside which fills the pore space 4 of the projected material. After rapid opening of the diaphragm a two-phase stream consisting of gas and stowing material is directed from the mouth into the exhausted working. In order to perform experimental studies of the process of projecting a two-phase stream into a closed bounded space in the form of a tunnel a unit was created whose layout is presented in Fig. 2. Several pairs of steel tubes closed from one direction and having a flange in the other were used as the discharge channel 1 and receiving channel 2. The tubes were of different shape and ratio of internal volumes. In the original state the discharge channel was filled with quartz sand and it was joined coaxially with the receiving channel through a sealing membrane made of Dacron 3. Opening of the sealing membrane was accomplished by heating a nichrome filament 4 fed from a supply unit 5. Filling of the pore space of the filler was accomplished by feeding compressed air from a cylinder unit 6 through a pneumatic flap 7. Monitoring of the initial pressures in the discharge and receiving channels was accomplished by manometers 8, 9. The change in pressure over the length of channels during the process was monitored by nine pressure gages DD-10 which were placed equidistantly along the channel length and a signal was fed through a pressure indicator to a loop oscillograph N-145. In the course of studies the original pressure in the discharge Pd and receiving Pr channels, the current pressure in different sections over the length of channels Pi (index i corresponds to the letters for gages in Fig. 2), equilibrium pressure PR in the system after the end of the process, the weight of residue material in the discharge channel n~, and the weight transferred to the receiving chaimel m r were measured. By equilibrium pressure PR we understand the pressure established in the system of closed channels after the end of the process. With a known value for the porosity of loose material II it may also be determined by the equation