Experimental investigation on flow properties of cemented paste backfill through L-pipe and loop-pipe tests

With the gradual depletion of available ore at shallow depth, deep mines have been widely operated around the world and therefore need a longer distance to transport the backfill to the underground stope. In this case, the determination of pressure drop is more important in the pipeline transportation system design. As the pilot loop systems require a large amount of capital and manual investment, even its results are reliable, there is an urgent need to find an alternative simple and cost-saving method to determine the pressure drop. Hence, laboratory L-pipe and a pilot-loop tests were employed to study the flow properties of cemented paste backfill cured at various solid and binder content. The results indicate that the L-pipe test presented a similar trend to the loop test, but the L-pipe was characterized by higher pressure drop values for various solid and cement contents. As cement content increased beyond 0%, the paste in the L-pipe showed a slighter difference in pressure drop evolution compared to the paste in the loop-pipe. These results suggest that the simple L-pipe is a workable substitute for semi-industrial loop tests and can provide guidance for designing practical CPB pipeline systems in deep mines.