Thiocyanate inhibition of microbial sulfide oxidation for the control and prevention of acid rock drainage

Thiocyanate is highly inhibitory toward the acidophilic iron- and sulfur-oxidizing microorganisms that accelerate formation of acid rock drainage (ARD). Thiocyanate added to samples of sulfidic waste rock, ore, and tailings from base metal and precious metal mines significantly reduced the formation of ARD in laboratory and field tests. Acidophilic microorganisms did not adapt significantly to thiocyanate nor did they biodegrade thiocyanate under aerobic conditions at low pH. Thiocyanate degraded slowly abiotically, producing ammonia.