Characterising the effect of microwave radiation on the magnetic properties of pyrite

The effect of microwave radiation on the magnetic properties of pyrite was investigated. The microwave source was a conventional multimodal reactor, with a frequency of 2.45 GHz and a maximum power of 1900 W. After treatment at 1900 W for 120 s, the recovery of pyrite in the magnetic fraction after separation increased from 8% (wet) and 25% (dry) to greater than 80% for both process streams. The improvement in recovery has been attributed to the microwave radiation altering the surface of the mineral, inducing the formation of new, more magnetic, phases. An increase in the magnetisation of the sample has also been noted, determined using a vibrating sample magnetometer (VSM). After exposure to microwave radiation, the magnetisation of the mineral sample increased by an order of magnitude. Microwave enhancement of the magnetic properties of weakly magnetic minerals could aid their removal from non-magnetic minerals such as galena and sphalerite, before other separation techniques are implemented, such as flotation, where gangue minerals act like the valuable ones.It is proposed that the VSM could be used to characterise the magnetic properties of minerals. Using this knowledge, more efficient processing flowsheets can be developed.