Abstract
The benefits of sensor-based sorting are slowly being realized by the mineral processing industry. As such, new and novel methods for sorting minerals are continually being investigated. One such technology is laser scattering. When optically translucent minerals, such as quartz, are illuminated with a laser, the laser light is scattered and transmitted throughout the mineral crystal causing it to be illuminated. This optical response from a translucent mineral is significantly different from that of an opaque mineral which reflects the laser light at its surface inhibiting it to interact with the mineral. Exploiting this optical difference in mineral responses enables optically translucent minerals to be differentiated and sorted from optically opaque minerals.
Quartz is the most abundant mineral in the earth’s crust and is optically translucent. Laser scattering can be used effectively to separate quartz minerals from other opaque minerals such as apatite, dolomite and basalt. As an example, quartz is associated with orogenic gold and as such, can be used as a proxy mineral for the recovery of gold. Quartz also occurs with rare earth elements (REEs) in bastnaesite. Removing the quartz from a bastnaesite deposit can upgrade the REE ore for downstream processing. Sensor-based sorting using laser scattering technology can be configured to recover quartz or to remove quartz depending on its value and the upgrading requirements.