SIMULATION EXPERIMENTS FOR THE INFLUENCE OF ORGANIC ACID ON THE FORMATION OF KAOLINITE

Using the reactions of fulvic acid(FA),humic acid(HA) and HCl with the natural minerals-feldspar,montmorillonite and mica under normal pressure and temperature,the dissolution and formation mechanism of kaolinite are explored.The experiments indicate that FA is in general more effective in dissolving aluminosilicate minerals than HA and HCl.The reason is the formation of FA-Si and FA-Al complexes which are more soluble and movable.FA-Al complex is preferred under acid condition whereas FA-Si complex under neutral and alkaline conditions.In FA system a little kaolinite were transformed from montmorillonite after 4 months,and from mica after 8 months.These results show that the kaolinite is easilier transformed from the layered minerals than from the framework silicate.The formations of six-coordination organo-Al complexes and organo-Si complexes have the important influences on the formation of kaolinite.