QUARRYING techniques could help save contractors cash by increasing the volume of metals recovered from recycling plants.
Scientists in Australia are adapting mineral processing techniques used by quarriers to concentrate ores to recover valuable metals from recycling plants.
The move will increase the amount of metal recovered from recycling centres and could bring about a drop in prices thanks to increased scrap levels.
By using quarrying processes scientists at the Commonwealth Scientific & Research Organisation claimed that large amounts of metals could be separated from waste sludge left over from the metal recycling process.
During recycling scrap metal is shredded. Electromagnets take out the large steel fragments for melting. Further separation processes remove the larger fragments of non-magnetic metals.
The process leaves a watery waste sludge that is typically sent to toxic waste dumps.
But this sludge can contain particles of steel, brass, copper and other metals.
CSIRO researcher Warren Bruckard and his team conducted a detailed analysis of sludge from a recycling plant and found that every tonne of dried sludge contained as much as 33 kg of steel and more than 3 kg of copper.
The techniques include concentrating the sludge to separate low-density materials from high-density materials and magnetic separation to concentrate steel.
Mr Bruckard claimed that the cost of installing extra plant would be offset by the value of the extra metal saved.