ECONOMIC FEASIBILITY OF RARE EARTH ELEMENT EXTRACTION FROM WYOMING COAL ASH/CHAR

The State of Wyoming is the largest producer of coal in the U.S.¹ Uncertainty over the future of this resource has caused the state to recognize the importance of diversifying its mineral industry. Recent research shows a potential remedy: coal by-products, such as fly ash, can contain recoverable amounts of Rare Earth Elements (REEs). By producing REEs from fly ash, Wyoming can diversify and add to its revenue streams. There is global demand for REEs, as they are utilized in the production of a diverse array of modern goods and technology.

Application of Net Present Value (NPV) analysis allows determination of the potential profitability of REE extraction from Wyoming coal-fired power station ash. The NPV analysis considers REE concentrations in six ash samples from two basins, the Powder River Basin and the Green River Basin. A challenge for NPV analysis of these samples is the lack of REE-from-coal-ash processing and refining cost estimates in the literature. To overcome this hurdle, the NPV analysis is structured to determine the maximum unit cost that a coal station can incur and still break even. For each station, this cost is calculated in two ways: as an input cost per pound of ash, and as an output cost per pound of Total Rare Earth Oxide (TREO). In addition to the unit cost, the analysis also provides the potential revenue and maximum capital cost for each station. Subsequent sensitivity analysis then allows for comparison of the results under scenarios that range from low to high yield and low to high REE concentrations.

With the assumptions made, five of the six coal stations have breakeven unit costs that exceed the value of 1.17 US$ per pound TREO, which is the mine-to-oxide operating cost reported by the hard-rock mine company Molycorp.² Under these results, REE recovery from Wyoming coal by-products appears economically promising.

¹ U.S. Energy Information Administration. 2016. Independent Statistics & Analysis: Frequently Asked Questions. “Which states produce the most coal?” Retrieved July 11, 2016 from http://www.eia.gov/tools/faqs/faq.cfm?id=69&t=2.

² SRK Consulting. 2010. Engineering Study for Re-Start of the Mountain Pass Mine and Processing Facility. Retrieved July 11, 2016 from https://www.sec.gov/Archives/edgar/data/1489137/000095012310065239/d74323fwfwp.htm.