The ever-growing demand in the USA and in the modern economy for rare earth elements, defined here as the lanthanide elements plus yttrium (REY), motivates the development of economically feasible and environmentally friendly approaches for domestic non-conventional sources, including coal mine drainage (CMD). We have analyzed CMD from abandoned coal mine sites in Illinois Basin and investigated trends in REY enrichment and their association with CMD geochemical characteristics.
Our results show that the CMD in the Illinois Basin exhibit larger heterogeneities of REY patterns than those described in other USA coal-mining districts. Significantly, the Illinois CMD have higher contents of REY and critical-REYCMD, with Y and Nd being the main critical-REY. Furthermore, CMD in the Illinois Basin were found to contain small amounts of economically valuable metals (i.e., Zn, Ni, Co, V) that could potentially be co-extracted with REY to enhance the economic values of CMD.
Synthesis of geochemical data suggests that hydrothermal activity probably played a key role in producing CMD enriched in metals and REY. Specifically, our data point towards two sources of REY enrichment in Illinois CMD, namely coal mine wastes containing solid matrixes (1) with high Al and Si contents (i.e., clay minerals and silicates) and (2) impact of hydrothermal solutions enriched in metals (i.e, Zn, Ni, Co) and REY. The sites with the highest contents of REY and critical-REY were predominantly located along the western and northern margins of Illinois Basin. Particularly, sites with the highest hydrothermal input as approximated by Mississippi-Valley-type mineralization are a prime candidate for REY and other metals (i.e., Zn, Ni, Co, Cu), potentially making Illinois CMD an attractive alternative source for REY and metals recovery. Thus, CMD in the Illinois Basin could become a potential alternative domestic source of extractable REY, especially critical-ΣREY, as well as economically valuable metals.
About the Speaker
Dr. Lefticariu is a broadly trained geochemist with cross-disciplinary links to several areas of biogeochemistry, economic geology, and coal geochemistry. Her specialty is low-temperature geochemistry with an emphasis on the stable isotopes of elements that play key roles in biogeochemical processes. Her research is devoted to solving diverse theoretical and practical problems with application in the geological and environmental sciences. Currently, Dr. Lefticariu is an Associate Professor at Southern Illinois University, Carbondale.
