Two-machine process recovers more than 80% of glass, with 95% purity
In developing AUTOSORT COLOR, TOMRA set industry standard-setting goals of recovering a minimum of 80% of glass from MSW, with at least 95% of the recovered glass of saleable quality. These targets were consistently met over many months at four facilities in Germany and Spain, including one which separates up to 3,000 tonnes of glass annually. This success was made possible by a two-machine sorting process, first using AUTOSORT LASER, then AUTOSORT COLOR.
The first step in the process of removing glass from MSW is pre-treatment. After the MSW passes through a bag opener, conventionally the fine fraction (0-80 mm) is screened-out. This fraction is then split into three categories by a double-deck vibrating screen: fine fractions of 0-8mm diameter, such as organic waste and sand, a middle fraction of 8-60mm and an oversize fraction of 60-80 mm.
In the second step, the middle fractions, which contain the highest glass content, are subjected to density separation. This removes the lighter fractions and sends the heavier fractions to the AUTOSORT LASER unit. Here a combination of laser (LAS) and near-infrared (NIR) detection technologies enables the separation of glass from the rest of the materials.
In the third and final step of the process, the innovative AUTOSORT COLOR machine classifies the glass fractions with a high-performance camera and separates any remaining impurities from the higher-quality glass. The result is the recovery of resaleable glass with a consistently high purity of more than 95%.