SLAG FROM HOPEWELL FURNACE PENNSYLVANIA AS A POTENTIAL RARE EARTH MINERAL SOURCE

Rare Earth Elements (REE) are important to society as they are critical components in a variety of industrial and technological applications. Lanthanum makes up as much as 50 percent of digital camera lenses, including cell phone cameras. Rare-earth magnets are utilized in automotive subsystems, such as power steering, electric windows, power seats, and audio speakers. Wind turbines use generators that require strong permanent magnets of neodymium-iron-boron. Currently we meet the demand for these minerals by importing REEs from other countries such as China. It would be valuable to explore homeland options in more depth. Reusing slag waste from old iron furnaces may serve the double purpose of removing contaminants from homeland soil and provide a new source of REE without the environmental costs of opening a new mine. Iron ores such as magnetite and hematite have the capacity to host REEs under some conditions. When iron ore is smelted to extract metallic iron, the waste product is a glassy material called slag. The purpose of this study is to determine whether iron slag contains economically significant concentrations of REE. Hopewell Furnace is an historic iron furnace in Berks County, PA that was in operation from 1775 to 1883. Slag from another historic Pennsylvania iron furnace, Centre Furnace (Centre County) has been shown to have total rare earth element concentrations around 900 ppm. Slag from the Hopewell Furnace may be similar and a viable source of rare earth elements. The major and trace element compositions of slag samples will be determined by electron probe microanalysis (EPMA), ICP-OES, and ICP-MS. If the REE concentrations in slag from Hopewell Furnace are comparable to those from Centre Furnace, cheaply and domestically sourced rare earth minerals could be available by reusing the waste products of iron smelting. This would be both an economically sound move and an environmentally friendly one.