Understanding microwave induced sorting of porphyry copper ores

• Published in: Minerals engineering Vol. 84; pp. 77 - 87
• Main Authors: John, R.S., Batchelor, A.R., Ivanov, D., Udoudo, O.B., Jones, D.A., Dodds, C., Kingman, S.W.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2015
• Subjects: Copper; Microwave; Modelling; Ore; Sorting; Microwave; Modelling; Ore; Copper; Sorting
• ISSN: 0892-6875; 1872-9444
• DOI: 10.1016/j.mineng.2015.10.006

•The effect of fragment texture on microwave-IR sorting of ores is investigated.•Heating of binary ore fragments examined using experimentally validated finite difference models.•Fragments with different textures show significantly different surface thermal responses.•IR measurement delay time shown to be critical in differentiating between high and low grade fragments. Global demand for minerals and metals is increasing. It has been established that the impact of mining and mineral processing operations must be reduced to sustainably meet the demands of a low grade future. Successful incorporation of ore sorting in flow sheets has the potential to improve energy efficiency by rejecting non-economic material before grinding. Microwave heating combined with infra-red temperature measurement has been shown to distinguish low and high grade ore fragments from each other. In this work, experimentally validated 2-D finite difference models of a theoretical two phase ore, representing typical fragment textures and grades, are constructed. Microwave heating is applied at economically viable energy inputs and the resultant surface thermal profiles analysed up to 2min after microwave heating. It is shown that the size and location of grains can dramatically alter surface temperature rise at short thermal measurement delay times and that the range of temperatures increases with increasing fragment grade. For the first time, it is suggested that increasing the delay time between microwave heating and thermal measurement can reduce the variation seen for fragments of the same grade but different textures, improving overall differentiation between high and low grade fragments.