Phosphate-induced metal stabilization using Apatite II™is ideal for treating acid rock drainage (ARD) or acid mine drainage (AMD).  It is best emplaced as a permeable reactive barrier (PRB) that treats the water as it exits the tailings, workings, adits, or other source. All that is needed is contact of the AMD with the Apatite II for times as short as 30 minutes. The Apatite II buffers the pH up to neutral, removing 99% of the toxic metals and most of the sulfate and nitrate. Even significant amounts of Fe and Al are removed. Since the Apatite II holds up to 20% of its weight in metals, more for some like U, and sequesters them in relatively insoluble phases, a relatively small amount will operate for many years.

Below is a synopsis of a small, 100-ton Apatite II PRB emplaced to treat AMD from a 500,000 cubic yard tailings pile at Success Mine in Idaho. After 5 years of operation, the PRB, had removed >4550 kg of Zn, >91 kg of Pb and >45 kg of Cd, and has buffered the pH to between 6.5 and 7 from an influent pH averaging about 4.5. The groundwater PRB treatment system is performing as designed.

• Applied Geochemistry Paper
• Uranium Paper
• Nevada Stewart Mine  

Success Mine Apatite II Permeable Reactive Barrier