Microwave treatment of mirerals and Ores

Abstract

Microwave energy has previously shown to have a major influence on the comminution behaviour of minerals and ores.significant reductions in bond work index heve been reported for microwave treated samples when compared to non-treated sample. It has been suggested that this is a result of differential expansion/contraction at grain boundaries.. Previous test work has been carried out utilizing "multimode" type microwave cavities. Although flexible, these cavities are known to be inifficient in their operation. This project has investigated the application of high electric field strengh microwave energy to minerals and ores and also measurement of diallectric properties of minerals. The application of high electric field strengh microwave energy means that the the heating rates of the materials are orders of magnitude faster. Tharefore, higher sample temperatures cam be reached more quickly and develop more, significant , stress fractures. Various important ore types and minerals have beeb selected and their textures, dielectric and thermal properties quantified. Ore strength, using UCS and point load index testing; specific comminution energy using a drop weight tester and grindability batch grinding and Bond Work index using ball mill have all been used to quantify the micriwave effect on ores. High electric fiel strenght microwave energy has been found to reduce the required sample cavity residence times to less than 0.2 seconds whilst enabling ore strength reductions of up to 70%. Mineral liberation assessment of microwave treated ores has also been conducted using QEM.SEM analysis and the research concludd with an analysis that shows that benefits are achieve with less than one kWh/t of the enetgy added into the process