Ecological Engineering and Biological Polishing methods are being developed on a pyrrhotite covered tailings area. INCO started the research work with the Reactive acid tailings (CANMET) program in 1985. This presentation summarizes the chemical, physical and biological results relating to the characteristics of a seepage creek emerging from a tailings dam.
It was found that organic matter (living and dead) in the seepage creek appears to provide a catalytic surface for precipitation of iron hydroxide from the water. Steady iron removal occurs over the upper 250 m of the creek. The hydraulic retention time of the creek water increases as the water enters a broad expanse (= pond) of a grass. A 6.5-fold reduction in total soluble iron occurs across this area (to a level of 0.2 ppm) along with a concomitant drop in pH of 2 full units. The latter acidification resulted in a re-solution of metals.