“Forensic engineering science” to aid process control of flotation circuits when processing difficult-to-float coal blends

Abstract

This paper presents an evaluation of flotation and downstream circuits from a coal processing plant producing metallurgical coal in Western Canada. The objective of the test work was to understand the causes for the occasional poor flotation performance when certain coal blends were processed at this plant. The specific objectives were to determine what differences existed in the composition of coal between the poorly- and normally-processing “standard” coal blends that can explain the observed poor flotation performance. For this study, the samples were taken from around the flotation circuit and from the thickener when “standard” blends were processed at the plant and subsequently, after the problematic blend entered the plant. Also, immediately after trouble shooting responses were triggered at the plant to control the situation. In order to accomplish this, a complete mineralogical, petrographic and surface properties’ assessment of coal samples was performed and this was complemented by the mineralogical analyses of ash forming minerals, slurry rheology on the samples from around the flotation circuit and the thickener at the time when the typical standard blend (non-problematic) and the troublesome blends were processed at the plant.