Autogenous dense medium separation using an inclined counterflow settler

An inclined lamella type device was used to separate particles on the basis of a difference in density. The feed slurry was pumped up through the device. Particles settled onto the inclined wall and slid to the base producing a concentrated underflow, while slower settling particles continued upwards producing the overflow stream. The particulate system chosen was PVC with a density of 1400 kg/m3 and ballotini with a density of 2370 kg/m3. The two species had the same terminal velocities in water, with the sizes of the PVC ranging within −250+125 μm and the ballotini ranging within −125+75 μm. Feed slurries of density less than 1150 kg/m3 were fed to the separator, producing internal suspension densities in the order of 1325 kg/m3. The autogenous medium was responsible for the separation of the PVC and ballotini, with an efficiency of 90% achieved at a solids throughput as high as 23 t/m2-h. A simple method for normalising the data generated using a broad range of feed slurry densities and feed rates is presented.