REPURPOSING OF PENNSYLVANIA IRON SLAG AS A LOW-IMPACT SOURCE OF RARE EARTH ELEMENTS

Rare earth elements (REE; Lanthanides + Sc + Y) are crucial for renewable energy generation and storage as they are used in the production magnets for wind turbines, specialized glasses for solar panels, and display screens, batteries for electric vehicles, and other technological and industrial advancements. These elements are essential and generally not found in high concentrations in the Earth. This project explores the possibility of recycling waste material from iron smelting into something beneficial for a more environmentally friendly future.

Specifically, the research targets a waste product formed during the iron ore smelting process at the historic Centre Furnace in Pennsylvania. Pennsylvania was the hub for iron production between 1716 to 1945 due to its abundant forests, limestone deposits, and access to running water. Slag is a glassy material composed primarily of silicon and calcium, with trace metals and other components. It results from a mx of iron ore and limestone flux in the furnace. While the iron settles at the bottom, slag floats on top and is usually discarded or used for road filing after extraction through a tap.

We find that slag from Centre Furnace contains 600-1000 ppm total REE. Total REE abundances in excess of 300 ppm are generally considered to be of interest. Slag from Centre Furnace contains 2-3x the threshold amount. In addition, because slags are pre-processed and non- crystalline, extraction of REEs should be simpler and more economical than extraction from mineral and rock-sources. Future work will determine whether high REE abundances are a common feature of Pennsylvania iron slags, or a unique feature of Centre County iron sources and waste products