In situ iron oxidation using hydrogen peroxide

Abstract

Hydrogen peroxide is used to oxidize ferrous iron at some acid mine drainage (AMD) treatment plants. Its potential use for in situ treatment of net alkaline mine drainage is evaluated in this study. Mine maps were used to identify an entry in the T&T #2 mine that was believed to channel the entire flow from that mine. Two wells, one existing and one new, were used to inject 35 percent hydrogen peroxide into the mine. A pump installed in a third downstream well was used to observe the changes in water chemistry resulting from the peroxide addition. Raw mine water contained 32 to 47 mg/L of predominantly ferrous iron, had a field pH of 6.4, and a field alkalinity between 118 and 170 mg/L. Hydrogen peroxide addition, controlled by a peristaltic pump, was able to demonstrate a linear dose response in situ. The pH and ORP were measured during bench scale testing of the mine water and were shown to be predictive of the ferrous iron oxidation end point. These end points were observed in situ. Based on data from the bench testing the flow in the mine was calculated to be 2.61 l/s. The chemical cost of implementing this technology was calculated to be $0.174 per mg/L ferrous iron per 100,000 liters treated. Copyright © (2010) by the American Society of Mining and Reclamation.