Improved Breakage and Flow in Sublevel Caving

To achieve a disturbance free fragmentation and flow in the sublevel caving (SLC), which leads to an increase in ore recovery and a decrease in waste rock loading and nitrates leakage. Decreasing disturbances will also create a more regular caving geometry and consequently fewer hang-ups and blocks, providing a safer work environment and finally cuts down the costs of maintenance.

The heart of the sublevel caving (SLC) process at LKAB consists of three steps a) blast function of caving rounds, b) fragmentation of caving panels and c) caving flow. For the ore recovery to be as high as possible and for the waste rock inflow to be as low as possible all three steps have to work as planned. The entire process is not visible to the naked eye. Without special tools it is not possible to say:

• How large the burden and spacings for the blast holes are

• If all the blast holes have effected complete breakage or caused back breakage

• If the detonators and the charge columns in the next charged ring are undamaged

• What fragmentation and flow mobilization look like

• If the ore being loaded is that which was blasted in the last round

To implement the experiences and results of internal LKAB projects, of ICS (International Caving Study) and MMT (Mass Mining Technology) projects and of Swebrec projects into field tests in the production at LKAB.
The tests are monitored by new and proven measuring methods so that a relevant judgement of the results can be made and a better conceptual flow model can be built.

Doctoral student: Matthias Wimmer, matthias.wimmer@ltu.se, tel +46-920-491454
Project leader: Prof. Finn Ouchterlony, finn.ouchterlony.swebrec@ltu.se, tel +46-8-6922293
Swedish Blasting Research Centre, Swebrec at Luleå University of Technology

Matthias Wimmer