Biological treatment of tailings solution at the Nickel Plate Mine

During the closure of the Homestake Nickel Plate Mine, located in south central British Columbia, there was a need to remove cyanide and other contaminants from water stored in the tailings impoundment prior to releasing the water to a nearby stream. Several water management and treatment alternatives were considered including land application, biological treatment, breakpoint chlorination, hydrogen peroxide, and the lnco SO2/Air process which was already in use at the mine. After extensive evaluations, the decision was made to use a combined aerobic and anaerobic biological treatment system for removal of residual cyanide, thiocyanate, ammonia, and nitrate, coupled with a High Density Sludge (HDS) process for removal of residual metals. The aerobic biological process utilized expertise and experience associated with the original biological treatment process still in use at the Homestake Gold Mine located in Lead, South Dakota, USA. The anaerobic biological process utilized experience developed through bench scale and pilot plant evaluations at the Nickel Plate mine. This paper will discuss the development and operation of the combined full scale biological treatment process. The discussion will include the decant or reclaim water characteristics, the basic process chemistry, the original bench and pilot plant evaluations, design considerations, effluent limitations, and an evaluation of the first year of full scale operation.Non UBCUnreviewedOthe