Leaching rates of rock-forming components through acidic alteration

A series of experiments on the interactions of a glassy basaltic andesite with acidic solution in a flowing system were carried out. Leaching indices of seven components (Na, K, Ca, Mg, Fe, Al and Si) were defined to compare the relative leaching behaviour of these components at all reaction stages. At 160 °C and using 0.24 N H2SO4 solution, Na, Ca and Al were leached easily, compared with K, Mg, Fe and Si. Although Si concentrated in the final residual rock, it was not always the hardest component to leach. The leaching behaviour of these seven components in a glassy rock agreed with that in crystalline rock. s of three experiments at 80, 120 and 160 °C using 0.12 N HCl solution showed that the rise of temperature accelerated the leaching rate of each component, whereas the leaching index for each component was not affected by temperature. This indicated that the leaching processes for these seven components were independent of temperature. other hand, in a series of the experiments at 160 °C using 0.24, 0.12 and 0.0024 N HCl solutions to examine the effect of acidity, the change in acidity of the reacting solution affected not only the reaction rate but also the reaction processes of the components. Na, Ca, Fe and Al became hard to leach as acidity diluted and Si became easy to leach and comparable to these components.