Study of electrokinetic properties of kaolinite in coal slime

The negative charge on kaolinite particles' surface is the main reason that causes coal slurry set difficulty.The effects of pH value,stirring speed,soaking time,cation concentration and type and kinds of minerals on Zeta potential of kaolinite particles were investigated by electrophoresis method.The results show that the Zeta potential of kaolinite particles increases when the suspension was stirred,meanwhile the Zeta potential decreases at the beginning and then increases with the increase of pH value and the prolonged soaking time,and the Zeta potential reaches minimum value when the pH value is 8 or the soaking time is 2 days,the activity of different cations that change the Zeta potential has the following tendency of Al3+Ca2+ Mg2+ Na+.The zeta potential increases due to heterocoagulating of different mineral particles in suspension.FTIR results indicate that the Zeta potential change account for the ion adsorption and the change of Si—O,Al—O and Al—OH of the surface of kaolinite particles.