Application of a magnetic cyclone on a magnetite dense medium separation process

Abstract

The face of coal supply and demand is ever-changing, with the demand for clean coal rising and with a dwindling supply of high quality ore. Methods to efficiently clean the coal of worsening run-of-mine quality are desperately needed. There are many facets, aspects and directions in which one can go when it comes to the beneficiation of coal in a more efficient manner, so there is not one answer that will address all the challenges faced. Many small changes to processes can accumulate and make a large contribution to the bigger picture. This dissertation focuses on one of the changes that can be made to a dense medium separation cyclone process in order to more efficiently beneficiate coal to meet the specific requirements so that the supply can keep up with the demand. The work done was to determine whether a coarser media could be used in a dense medium cyclone separation system that would lead to a reduction in media losses, an increase in yield and ultimately a financial benefit to implementing such a system. Coarser media on its own would not work, as it would settle and cause media instability within a dense medium cyclone. Fortunately, a system of solenoids, known as SpecSepTM, was designed to aid in the stabilisation of the coarse media. From the study, it was found that adding coarse media to conventional media decreased the density differential quite significantly in instances where a magnetic field was applied. An optimum ratio of coarse-to-fine magnetite was established and tracer tests were done. From the tracer tests, it was evident that the efficiency of the dense medium cyclone could be improved when the SpecSepTM solenoids were applied, and also the cut-point could be lowered. It was finally determined that there is a saving in costs relating to a reduction in magnetite losses for a SpecSepTM system, the payback period for the implementation thereof is fairly quick, and that there is a huge profit that can be made annually if the SpecSepTM system is used.