Reducing the entrainment of clay minerals in flotation using tap and saline water

• High entrainment of kaolinite Q38 occurred in flotation.
• The entrainment was higher in saline water than in tap water.
• The addition of PEO in flotation reduced kaolinite entrainment in particular in tap water.
• Less compact aggregation structures of kaolinite particles occurred in saline water.
• Saline water and a high PEO addition enhanced froth stability.

High gangue entrainment is a major problem in fine particle flotation. In this study, the entrainment of kaolinite Q38 in flotation was examined in tap and saline water. High molecular weight polyethylene oxide (PEO) was used to reduce the entrainment of kaolinite Q38 by enlarging the size of kaolinite particles in flotation. It was found that PEO reduced the entrainment significantly in flotation using tap water, but in saline water, the effect of PEO was less pronounced. The aggregation behaviour of kaolinite Q38 particles in the absence and presence of PEO and its effect on the entrainment of kaolinite Q38 were studied by the in-situ measurement of flocs and the size of enlarged particles, settling tests and the measurement of froth stability in flotation. It is interesting to find that PEO did flocculate kaolinite Q38 particles and enlarge their sizes in flotation despite high agitation. However, the reduction of the entrainment of kaolinite Q38 in flotation was dependent on the type of flocs formed and froth stability which can be modified by electrolytes in water and a high addition of PEO.

The entrainment of kaolinite Q38 in flotation was higher in saline water than in tap water. PEO reduced kaolinite entrainment in tap water as a result of the formation of flocs by particle bridging. The effect of PEO in saline water was less pronounced due to the formation of less compact flocs and higher froth stability.Figure optionsDownload as PowerPoint slide