RECOVERING METALS FROM ACID MINE DRAINAGE THROUGH ELECTROLYSIS: A PILOT
STUDY
Elaine R. Goetz1, Husam A. Abu Hajar1, *R. Guy Riefler, PE, PhD1, and T. Chris Wilson, PE2
1
Department of Civil Engineering
141 Stocker Center
Ohio University
Athens, OH 45701
(*Corresponding author: riefler@ohio.edu)
2
Wayne National Forest,
US Forest Service
13700 US Highway 33
Nelsonville, OH 45764
ABSTRACT
The eastern and southeastern regions of Ohio are part of Appalachian coal country, with a documented
1,300 miles of streams impacted by acid mine drainage. Since 1995, partnerships of local watershed groups,
government agencies, private industries and universities have focused on the remediation of the affected waterways.
The partnerships have spent $2.4 million annually in constructing and operating treatment systems such as wetlands,
anoxic limestone drains, successive alkalinity production systems, steel slag leach beds, and lime dosers. These
systems have been partially successful, and water quality has improved in the region, but no treatment has yet met
the ultimate objectives of low cost, continual remediation. Our research group has investigated an alternative system
for acid mine drainage treatment: electrolysis combined with pH adjustment to selectively precipitate recoverable,
saleable metal products to offset the cost of treatment. We utilized a $0.2 million pilot facility constructed by the
Wayne National Forest, in Nelsonville, Ohio, to process approximately 40 L/min of mine drainage from surrounding
seeps. The pilot facility has multipurpose tanks that can be adapted to process acid mine drainage with different
characteristics, such as high or low aluminum content or high or low carbonate concentrations. Sodium hydroxide
was used for pH adjustment. Results indicate that saleable product can be generated with this treatment technology.
In an initial, not optimized trial, one seep yielded 4.7 kg of dried 69% iron oxide product from 10 hours of pilot
facility operation, treating 23,000 L with electricity costs of $4.68. Dissolved iron concentrations in the water were
reduced from 242 ± 18 mg/L to 2.8 ± 2.0 mg/L (99.0% removal) while the initial acidity of 443 mg/L as CaCO3 was
neutralized to an alkalinity of 160 mg/L as CaCO3. Iron oxide can be sold as pigment for an average of $1.47 per kg
in the United States. Currently, approximately 80% of all pigment used in the United States is imported, and there is
incentive to purchase domestically recovered pigment. If the iron oxide from the pilot facility could be sold as
pigment for $1.47 per kg, 43% of the operating cost (raw materials, electricity and construction costs) of treatment
could be offset by the sale of the product. Considering the cost offset, the electrolysis process shows potential as a
sustainable low cost alternative for treating acid mine drainage.