German engineering company 
Commodas, part of the Tomra group, has developed technology 
that will make ore sorting applications more accurate, reports the company.

Commodas sales and project manager Fabian Riedel says that the technology uses computer software to separate run-of-mine ore before it goes for crushing.

“The material gets fed into the system through a conveyor, passing an optical camera that takes a picture and defines it by certain preprogrammed criteria. Any 
material that fits the criteria gets separated from the rest by air valves that shoot spurts of air to blow accepted particles into a concentrate chute. The selected particles then go through the relevant comminution and final concentration processes,” says Riedel.

He adds that the computer pro-
gram “takes a decision based on the colour, brightness and shape of the feed material”. Because of this, the particles need to be washed before being sorted by the optical equipment.

The technology has been on trial at minerals research organisation Mintek since 2001.

Mintek physical separation specialist Carl Bergmann says that the technology has a long history in the quarrying and aggregate sector in Europe and it will take the experience gained in those sectors to be put to use in a broader minerals processing context.

He reports that the technology 
is currently being tested in the platinum-group metals, gold, coal and base metals sectors.

Riedel states that a feature of the technology is its robustness. 
Based on the measurements of the feed material, the machine can sort at a rate of 75 t/h.

Commodas also makes X-ray sorting machines, which work on a similar principle to that of the optical sorting machine.
However, with the X-ray 
machines, the particles’ atomic density plays a bigger role than in the optical machine. Unlike the process in the optical sorting equipment, the particles used in the X-ray process do not need to be pretreated in any way.