Investigation of leaching rate on minerals for development of groundwater quality evolution model

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1. Survey on leaching rate of pyrite, chlorite, epidote and siderite. (1) Pyrite Reaction rate (K) is depended on dissolve O concentration in Lin's literature. 1 - (1-x) = k [O] ・t (x: Mole number of dissolved FeS , [O]: Dissolve O concentration. T:Time) Reaction rate is changed by temperature. k = 2.2 10 exp(-9140/T) (2) chlorite Reaction rate is measured 2.7 6.7 10 mol/m/s(pH3 4.5) by Swoboda-Colberg et al. Reaction rate is controlled by inner diffusion. (3) Epidote Reaction rate is measured 10 10 mol/cm/s in pH1 11 by Rose. (4) Siderite Reaction rate is measured 9.93 10 mol/m/s in O-free solution by Greenberg et al. 2. Experimental study on leaching rate of minerals. (1) Measurement of leaching rate of minerals. Leaching rate of pyrite was measured in distilled waster under redox condition. Reaction rate (K) was estimated 10 10 (cm・mol) 1/2・h by Lin's rate equation. At 56 days in the experiments. Alterated layer could not be found in SEM and EDX observation. (2) Measurement of leaching rate of chlorite Leaching rate of chlorite was measured in distilled waster under air condition. Disolution process of chloric was parabolic Stage, and reaction rate (K) was estimated order of 10 10 by Ross's rate equation. = kt [ : disoleved mineral amount / intial mineral amount, t : time(sec) ] At 56 days in the experiments, alterated layer could not be found in SEM and EDX observation.