Performance quantification of applicators for microwave treatment of crushed mineral ore

Bradshaw S.M. ; Ali A.Y. ; Marchand R. ; Barnard A. (2011)


Exposure of crushed mineral ores to microwaves at high power density (∼10 9 to 10 11 W/m 3 abs) and for short exposure times (<0.1 s) induces grain boundary fracture around the grains of the value minerals at economically viable energy inputs (∼1 kWh/t). In subsequent processing steps, liberation of the value minerals is enhanced, improving the efficiency of the process. In this paper the performance of transverse E-field applicators for the continuous treatment of 30 t/h of crushed ore was quantified using damage maps. These provide the amount of microwaveinduced grain boundary damage and the fraction of the load treated as a function of input power and throughput. The damage maps are created by combining the outputs from thermal stress simulations (for the determination of thermal damage) with those from electromagnetic simulations (for the determination of the 3d dissipation of power in the load). The results are to be used to select the optimal applicator structure and operating parameters (bed height and speed) for a given ore. Results from two applicator configurations for a coarser and finer-grained galena-calcite ore are used to exemplify the results. It is shown high the texture of the ore significantly reduces performance in terms of achievable throughput and required energy input. It is also shown that sub-optimal electromagnetic design also results in reduced throughput and increased energy requirement.

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