Evaluation of an On-Line Ash Analysis System for Low-Grade and Inhomogeneous Greek Lignite

Abstract

The possibility of using commercial on-line analysis systems for monitoring the ash content of low-grade lignites was investigated by carrying out numerous bench-and pilot-scale trials in the mines of Public Power Corporation SA, Greece. Pilot-scale trials were based on a dual-energy γ-ray transmission analyzer, which was installed on the conveyor belt that transports lignite from the pit to the bunker of Kardia mine, Ptolemais. According to the obtained results, the accuracy of the on-line measurements was not adequate and did not allow lignite quality monitoring in real time. The deterioration of the on-line measurements' accuracy, compared to previous applications in other mining sites, was related to the intense variation of the lignite ash content and ash composition, which distorted the calibration of the analyzer. The latter is based on certain assumptions regarding the average atomic number of the organic and mineral matter contained in the lignite. Further experimental work is needed to investigate solutions for successful implementation of this method to lowgrade lignites that exhibit large variation in ash content and composition.