Sensor-based sorting

Sensor-based sorting, is an umbrella term for all applications where particles are singularly detected by a sensor technique and rejected by an amplified mechanical, hydraulic or pneumatic process. The technique is generally applied in the three industries mining, recycling and food processing and used in the particle size range between 0.5 and 300 mm (0.020 and 11.811 in). Since sensor-based sorting is a single particle separation technology, the throughput is proportional to the average particle size and weight fed onto the machine.

The main subprocesses of sensor-based sorting are material conditioning, material presentation, detection, data processing and separation. Material conditioning includes all operations which prepare the particles for being detected by the sensor. All optical sensors need clean material to be able to detect optical characteristics. Conditioning includes screening and cleaning of the feed material. The aim of the material presentation is the isolation of the particles by creating a single particle layer with the densest surface cover possible without particles touching each other and enough distance to each other allowing for a selective detection and rejection of each single particle. There are two types of sensor-based sorters: the chute type and the belt type. For both types the first step in acceleration is spreading out the particles by a vibrating feeder followed by either a fast belt or a chute. On the belt type the sensor usually detects the particles horizontally while they pass it on the belt. For the chute type the material detection is usually done vertically while the material passes the sensor in a free fall. The data processing is done in real time by a computer. The computer transfers the result of the data processing to an ultra fast ejection unit which, depending on the sorting decision, ejects a particle or lets it pass.

Sensor-based ore sorting is the terminology used for sensor-based sorting in the mining industry. It is a coarse physical coarse particle separation technology usually applied in the size range for 25–100 mm (0.98–3.94 in). Aim is either to create a lumpy product in ferrous metals, coal or industrial minerals applications or to reject waste before it enters production bottlenecks and more expensive comminution and concentration steps in the process. In the majority of all mining processes, particles of sub-economic grade enter the traditional comminution, classification and concentration steps. If the amount of sub-economic material in the above-mentioned fraction is roughly 25% or more, there is good potential that sensor-based ore sorting is a technically and financially viable option. High added value can be achieved with relatively low capital expenditure, especially when increasing the productivity through downstream processing of higher grade feed and through increased overal recovery when rejecting deleterious waste.

...
Wikipedia