Both LCC and HCC were screened to 710 lm following the
bore core procedure of the coal mine. In the coal plant, the particles
greater than 710 lm are subjected to gravity separation, while the
particles smaller than 710 lm are floated. Previous studies in the
plant indicated that minerals were well liberated in both feeds to
gravity and flotation circuits. The cut-off size for gravity and flotation separation was chosen primarily based on the size limit of
gravity devices. The particle size distribution of the flotation feed
of LCC with 7% clay minerals and HCC with 33% clay minerals is
showed in Fig. 1 . In the plant, LCC is referred to as coarse coal with
about 51% particles greater than 150 lm, while HCC as ‘‘clay’’ due to the high clay content. In this study, besides floating LCC and HCC
separately, 80% LCC and 20% HCC were mixed to make a coal sample having 12% clay minerals (medium-clay-content-coal, MCC)
and floated to study the effect of a higher proportion of clay minerals on coarse coal flotation and whether the two clayey samples
can be blended and then floated. The current view is that clay minerals have a deleterious effect on the flotation and any higher clay
mineral content will exacerbate the flotation