Thursday 3:25 Dr. Robert S. Hedin, Hedin Environmental & Iron Oxide Recovery, Inc.
Successful Production of a Marketable Iron Product from Mine Drainage Sludge.
Robert S. Hedin, Ph.D.
In 1994 Hedin Environmental received a Small Business Innovation Research award from the US Department of Agriculture to investigate the feasibility of producing useful products from iron-rich mine drainage sludge. The investigation determined that passive treatment processes could produce an 85-95% pure iron oxide solid and also identified existing markets for iron oxides in metal, water treatment, catalyst, magnetic, and pigment industries. The most promising market proved to be the pigment market. In 1999 an opportunity developed to recover about 1000 tons of 80-90% pure iron oxide from an abandoned deep mine site in southwestern PA. A pigmentary customer was identified who required a 50% solids, clean product. R&D support was received from the PADEP, OSM’s Resource Recovery Program, and the Heinz Endowments. Between 2000 and 2003, a saleable product was produced by a variety of recovery, dewatering, and screening methods. The most efficient production method involved pumping, wet screening, and dewatering with frame filter presses. The least costly production method involved excavation, passive dewatering, and dry screening. In 2003 and 2004, production occurred at three new sites, all of which were passive treatment systems where excessive iron sludge accumulation had decreased performance. Unfortunately, not all mine drainage treatment systems yield pigment-quality iron oxides. Iron sludges formed under acidic conditions or ones formed where oxidation is accelerated by chemical or physical means generally have poorer pigment characteristics and, at this time, are not marketable as pigments. Other uses for these iron sludges are being investigated. The presentation will describe the recovery of pigment-quality iron oxide and provide information on investigations into other uses.
Bob Hedin has a Ph.D. in Ecology from Rutgers University where he studied plant communities and soils on abandoned mine sites in western PA. Between 1987 and 1994, he was a research biologist with the US Department of the Interior, Bureau of Mines. His work involved the geochemistry of mine drainage and passive treatment of coal mine drainage. In 1994, Bob left the Bureau of Mines and formed Hedin Environmental. The small firm specializes in the assessment and remediation of polluted coal mine drainage, primarily by passive methods. One of the firm’s first projects was an investigation of the feasibility of producing a saleable product from mine drainage sludge. This project eventually resulted in the formation of Iron Oxide Recovery, Inc, a company whose primary purpose is the profitable production of iron oxide products and the design/construction of treatment systems that produce saleable iron oxides.