Simultaneous Aeration and Neutralization of Mine Water: An Apparently Forgotten Discovery

About 40 years ago, the U.S. Bureau of Mines developed a simple mine water treatment approach that appears to have largely been forgotten. The in-line aeration and treatment system or more simply, the in-line system (ILS), was designed to treat acid mine drainage (AMD) within existing AMD pipelines. The initial device consisted of two inexpensive off-the-shelf components, a jet pump, which entrains air by Venturi action, and a static mixer, which induces turbulent flow. The system had no moving parts, could easily be assembled on site, and was designed to use the pressure generated by an existing mine water discharge pump. In pilot-scale and full-scale field tests, it was shown to be effective for treating both coal and metal mine drainage, on the surface and underground. Moreover, the iron oxidation kinetics and efficiency of lime consumption far exceeded that which occurred in normal active treatment plants.