Effects of water hardness on selective flocculation of diasporic bauxite
(School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China)
Abstract: The effect of electrolyte on settling behavior of kaolinite was studied. Effects of hard water on selective flocculation of diasporic bauxite was tested and the measures were taken to eliminate the effects of Ca2+ and Mg2+ in hard water. The results indicated that, not only the concentration of electrolyte ions but also the ionic valence of the electrolyte ions affects the settling behavior of kaolinite; hard water significantly affects its selective flocculation owing to Ca2+ and Mg2+; general dispersants could not eliminate the effects of Ca2+ and Mg2+. Self-made softening agent in our lab could weaken or eliminate the effects of hard water on flocculation processes. The results of molecular dynamics simulation show that softening agent molecules could restrict Ca2+ and prevent them from playing their roles, so as to eliminate the effects. The continuous pilot experiment results of bauxite flocculation were even better than those obtained in laboratory.
Key words: softening agent; hard water; bauxite; dispersant; flocculation