Macrostickies measurement by an automated method using laser triangulation and near infrared spectroscopy

In recycled paper processes, stickies are at the origin of many production disturbances, such as machine breaks, defects in paper and converting problems. Typically, a macrostickies measurement involves separating them from the pulp by screening, then characterising by one of the available inspection and classification methods. The most recognized method in Europe is INGEDE#4. It gives useful information about stickies particles count and size. However the measurement is time-consuming, because of the manual preparation involving numerous steps. In this work, we present an automated macro-contaminant measurement method which allows to (i) determine the 3 dimensional morphology of screened particles (without any deformation) and (ii) classify the particles as stickies among contaminants. This is achieved by a combination of laser triangulation and local near-infrared (NIR) spectroscopy. Starting from the screened contaminants deposited on a filter paper, the stickies measurement is fully automated. The stickies count results from the proposed method are closely correlated with those from the INGEDE#4 method.