Humidity Cell Tests: Effect of Air Flow and Cycle Duration in the Quality of Leachates

摘要

A factorial experimental design was used for humidity cell tests conducted for 10 cycles ontailings containing 71% pyrite to determine if the rate of air flow (3 and 6 Lmin~(-1)) and cycleduration (14 and 21 days) affected leachate pH, electrical conductivity, and Eh. The tailingscomposite sample for the tests was taken from Tizapa, a massive sulfide mine located southwestof Mexico City, Central Mexico. The method ASTM D 5744-96 was taken as the basis for thedesign of the cells with two modifications: 1) air was circulated across the surface of the tailingsand 2) water was dropped directly emulating rain on a tailings darn. Examining drainage qualitydata by cycles indicated the four treatments did not significantly affect the pH, but it was foundthat the air flow rate had a significant effect in the quality of leachates. The higher air flowdelayed acidification, probably due to excessive water loss that inhibited oxidation reactions.