ABSTRACT
The sublevel caving mining method principle is to fragment a slice of ore standing almost vertical 80-85°. The thickness (burden) of the slice might be in large Scale Sublevel Caving (SLC) about 3 m and the number of blastholes to fragment the slice may have a diameter of 102-115 mm and could be about 8 to 10 and fan orientated upwards at LKAB in Kiruna today. The sublevel height is 25-30 m today. To keep the slice in place the SLC method demands that the surrounding caved rock mass exerts a pressure on the blasted slice before, during and after blasting. The fragmented ore will then by gravity flow down to an underlying drift (cross cut) where the fragmented ore will be loaded and transported by a Kiruna truck or Load Haul Dumper (LHD) to an ore pass shaft. If the swelling of the ore is not enough the mobility of the ore will be too low so the main mass can not move, only the smallest pieces, created in the vicinity of the blastholes, will then move down by gravity forces. The hypotheses tested in the technical licentiate thesis was therefore, if we in model tests can study the dynamics of the blasted ore and thereby learn the kinematics of the blasted round in detail and get a better understanding of the swelling process of the ore when blasting against waste rock and finally be able to make a better blast design for a full scale mine and to avoid freezing of the ore.
