煤泥水中高岭土颗粒表面荷电特性研究

Study of electrokinetic properties of kaolinite in coal slime

煤泥水中高岭土颗粒表面电负性是其难以沉降的主要原因.采用电泳法研究了pH值、搅拌强度、浸泡时间、阳离子浓度与种类对高岭土颗粒表面Zeta电位的影响规律及不同矿物之间的相互作用.结果表明,搅拌使高岭土颗粒表面Zeta电位增大;Zeta电位随pH值增大和浸泡时间的延长先减小后增大,在pH值约为8及浸泡2d时均达到最小值;不同阳离子改变高岭土颗粒表面Zeta电位能力顺序为Al 3+>Ca2+>Mg2+>Na+;不同矿物颗粒间因互凝作用会增大颗粒表面的Zeta电位;FTIR分析表明,悬浮液中离子在高岭土颗粒表面的吸附及表面Si-O,Al-O及Al-OH基团的变化是其颗粒表面Zeta电位变化的内在原因.

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 A1a＋ 〉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,AI--O and AI--OH of the surface of kaolinite particles.