Abstract
It has been found that selective resinite flotation from Wasatch Plateau coal can be achieved at high pH. For example, a high grade resin concentrate (>70% resin) was obtained at an excellent recovery (>90%) by single-stage flotation above pH 12 from a feed containing only 7.2% resin. This rougher concentrate was then cleaned to produce a cleaner concentrate containing >90% resin. The flotation results thus obtained by pH control can be explained to be due to: (1) improved dispersion of the resinite/coal suspension as evidenced by microscopic observation, electrokinetic behavior, and sedimentation phenomena: and (2) improved depression of coal particles; their hydrophilic state being stabilized by surface precipitation and/or adsorption of calcium species at higher pH values as determined by FTIR and XPS spectroscopic analysis.