Feasibility of lime treatment at the Leviathan Mine using the in-line system

The In-Line System (ILS) was used in a pilot-scale water treatment study at the Leviathan Mine in California. The Leviathan Mine is a remote, abandoned, copper/sulfur mine. This study addressed two questions: (1) Can the severely polluted mine drainage at the Leviathan Mine be treated with lime to an acceptable quality? and (2) Can a neutralizing reagent formulation (using various ratios of lime, fly ash, and cement) be designed to improve the physical characteristics of the resulting sludge for disposal purposes? The primary pollutants of concern are arsenic, nickel, aluminum, iron, and sulfate.Pilot-scale studies at the Leviathan Mine show that an in-line system (ILS) can be used to treat the severely polluted pond and adit water to meet the U.S. Environmental Protection Agency’s National Ambient Water Quality for Freshwater Aquatic Life Protection (1-hour acute toxicity) criteria. Lime and lime-based admixtures were used to neutralize the adit and pond waters. The optimal treatment pH range was 6.9–7.9 for adit water, and 6.5–8.0 for pond water. The ILS served as a neutralization and mixing system for treating both water sources, and also as an aeration system for treating the adit water. The ILS effectively oxidized nearly 900 mg/L of Fe+2 within 30 seconds of contact time when treating the adit water. Additional work is needed to evaluate sludge alternatives.The simplicity, portability, flexibility, and economics of the ILS make it a prime candidate for remote treatment operations such as the Leviathan Mine. Furthermore, the ILS can operate by water power with elevational differences of 50 ft or greater. The need for permanent electrical power installation for water treatment can possibly be eliminated by coupling the ILS with a commercially available water-powered lime feed system.