The effect of clay slimes on coal flotation, part II: The role of water quality

B. J. Arnold, F. F. Aplan

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Suspended clay solids, ions, pH and humic acid are shown to have a significant influence on coal flotation. Coal flotation is greater in tap than in distilled water. This is believed due to instability and thinning of the hydrated layer at the surface of the coal particle when ions are present. The loss of recovery in the presence of clay slimes is more pronounced in distilled water than when ions are present. In both cases coal depression is much greater with bentonite than with kaolinite or illite clays. The greater surface area, surface-charged sites and ion-exchange-capacity enables bentonite coatings to be established by electrostatic attraction of the clay to the coal. The presence of humic acids is shown to depress coal readily in either distilled or ion-contaminated water.

Original languageEnglish (US)
Pages (from-to)243-260
Number of pages18
JournalInternational Journal of Mineral Processing
Issue number3-4
StatePublished - Jul 1986

All Science Journal Classification (ASJC) codes

  • Geotechnical Engineering and Engineering Geology
  • Geochemistry and Petrology


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