Development of a video-based slurry sensor for on-line ash analysis. Final technical report, October 1, 1994--September 30, 1996

Automatic control of fine coal cleaning circuits has traditionally been limited by the lack of sensors for on-line ash analysis. Although several nuclear-based slurry analyzers are available, none have seen widespread acceptance. This is largely due to the fact that nuclear sensors are expensive and tend to be influenced by changes in seam type and pyrite content. In this investigation, an image analysis technique is used for on-line determination of ash content in fine coal slurries. The ash content of a flotation tailings stream is correlated to the mean gray level of the slurry. Based on a 90% prediction interval, an analysis of sensor performance indicates an accuracy of 73 {+-} 4% ash over a range from 65 - 90% ash. While this result is comparable to existing nuclear-based analyzers, the video-based system is only a fraction of the cost. The sensor is currently being used to monitor the column flotation tailings stream at the Middle Fork preparation plant owned and operated by Pittston Coal Company