Abstract: In response to the known drawbacks of liming and the ever-increasing regulatory demands on the mining industry, KEECO has developed a silica micro encapsulation (SME) process. SME is a cost-effective, high performance reagent that is utilized in conjunction with simple chemical delivery systems. By encapsulating metals in a silica matrix formation and rapidly precipitating them into a sand-like sludge, it offers all the advantages of liming without the negative drawbacks. Utilizing an injection technique via a high shear mixing device, a slurry from of the SME product called KB-1 (super TM) was applied to ARD at the Bunker Hill Mine in Idaho and to ARD pumped from collection ponds at a remote mine site in the Sierra Nevada Mountains. Flow rates at both sites ranged from 500 to 800 gallons per minute. Treated water from the Bunker Hill Mine operation achieved the site's NPDES criteria for all evaluated metals and U.S. Drinking Water quality for arsenic, cadmium, chromium, lead and zinc with a dosage rate of 1.34 grams KB-1 (super TM) per liter. Treated water from the Sierra Nevada project focused on the control of aluminum, arsenic, copper, iron and nickel. All water samples displayed a >99.5% reduction in these metals, as well as an 84%-87% reduction in the concentration of sulfate. Testing on sludge generated from both operations achieved TCLP Action Limits. The SME process is currently under evaluation as a means to coat the pyrite surfaces of newly generated mine tailings to prevent oxidation and future acid generation.