Application of the heavy suspension technique for ore beneficiation plant feed characterisation from the Southern Middleback ranges

This paper outlines a comparison of heavy liquid and heavy suspension separation methods for iron ore characterisation. As part of Arrium Mining’s program to improve its knowledge of ore types being processed in its two hematite ore beneficiation plants (OBP), metallurgical evaluation of hematite feed for the upgrading process has become a major focus. Iron ore deposits almost always contain more than one valuable (and relatively dense) iron mineral. Iron ores are found with a range of iron contents, giving rise to density variations. At present the industry relies on heavy liquid separation techniques for the evaluation of iron ore samples arising from exploration, mining or metallurgical processes. There are only a few highdensity liquids available, which are both high-cost and highly toxic. Low-toxicity solutions that can be utilised at relative densities up to 3.0 have been developed. However, highly-toxic organic liquids are required presently to achieve relative densities beyond 3.0. Bromoform which has a specific gravity (SG) of 2.89, and diiodomethane (SG 3.31) are commonly used; both present significant health and safety hazards. ‘Clerici’s solution’ (mixtures of thallium formate and thallium malonate) provide liquids having specific gravities between 4.0 and 5.0. Clerici’s solution is highly toxic and testing is currently conducted by a limited number of laboratories worldwide. An alternative to Clerici’s solution and organic liquids is a low-toxicity, high-SG, suspension technique, which has been demonstrated successfully for heavy mineral sands. This heavy suspension method employs mixtures of fine tungsten carbide particles in lithium heteropolytungstate (LST) solution