Microwave heating of ores to replace both conventional value-sensing and Air-blast sorting

Depleted ore deposits can be given new life, satellite deposits opened up and greenfield ore developments can reduce capital and water usage requirements. However, there are restraints to the technology. One is the cost of separating valuable rocks from waste rocks. Currently, this is achieved by blasts of air from high speed actuators at the discharge end of the belt carrying the rocks. Running air compressors can constitute some 75% of the operating costs of the machine sorter.
The concept presented herein requires neither air blasts, nor value sensors. It makes use of the fact that certain minerals, principally sulphides, heat up in a microwave energy field, whereas waste gangue minerals such as carbonates and silicates do not. By placing a MW treated mixture of valuable and waste rocks on a belt which is covered by a (thin) layer of thermo-sensitive adhesive compound (think carton glue), the trajectory of rocks upon discharge can be made to depend on the degree of adherence of a rock to such a belt and thus allow separate retrieval of valuable and waste rocks. A low temperature adhesive will lower the energy input required for MW heating. The thermo-adhesive layer will likely have to be formulated for stickiness and softening temperature per application, and the resin may periodically have to be re-applied due to dust adherence. These are development items and call for cooperation with a thermoplastic compounder.