Rotary-vacuum filtration of coal flotation concentrates

Vacuum-filter capacity can only be reliably determined if accurate data is available from laboratory and pilot-scale tests with samples of the material ultimately to be filtered by the commercial unit.Pilot units are invariably relatively flexible models of the commercial unit but the scope of the testwork must be minimised wherever possible because of the large sample volume involved.Laboratory bench-scale apparatus must therefore be used to provide the basis for determining the extent of specific information required from pilot-plant work. All too often however, this apparatus bears no resemblance to the operational behaviour of a particular filter type. Laboratory tests conducted with a closely simulated apparatus can provide valuable information and because the apparatus is very flexible, the type of testwork which can be accomplished can take into account varying operating conditions and allow optimized operation to be predicted. Such testwork need not involve a very large bulk sample of the slurry. It is not however satisfactory to base filter design totally on laboratory data and it is essential that pilot-scale work be carried out with a suitable model of the eventual commercial machine. Pilot units are now readily available from filter manufacturers and it is possible for testwork service to be obtained or for the machine to be hired.The paper contains an approach to obtaining rotary-vacuum-filter capacities for coal concentrate treatment and demonstrates comparative results obtained with bench, pilot and full-scale tests.