Impact of Particle Size in High-Tension Roll Separation

摘要

The High Tension Roll (HTR) separator is widely used in the processing of minerals sands to separate particulate mixtures containing a liberated combination of relatively conducting and non-conducting mineral species. A typical application of HTR separation is to sort ilmenite and rutile, relative conductors containing titanium, from zircon, a relative non-conductor mineral. These species are important industrial mineral products with a variety of uses across multiple disciplines, including paint whitening, glazing and the production of the highly prized titanium metal. The performance of HTR separation ranges widely between operations and the specific conditions particular to local equipment set up, feed properties and conditions. This paper discusses the importance of relative particle size on HTR separation efficiency. The impact of electric fields on inter-particles interactions is given specific attention, as this area has been given limited investigation in previous studies, yet has a significant effect on separation behavior. In particular, the forces between particles of different charge, size and conductivity, as well as the particle distribution pattern on the roll surfaced will be analyzed in detail. The charging and discharge dynamics of an isolated charged particle resting on a conducting surface are studied first, and the analysis is extended to particle discharge in a homogenous particle bed, as on a HTR roll surface. Finally, the analysis considers the more realistic scenario of particle discharge in a non-homogenous, multi-size particle bed. The consequences of particle interactions, the resulting forces, and thus separation behavior in HTR operation are discussed. The resulting study shows how various particle combinations and blends can impact HTR separation efficiency negatively, or indeed improve it, depending on specific conditions.