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POTENTIAL FOR CRITICAL MINERALS IN COAL MINING PRODUCTS, BYPRODUCTS, AND REJECTS, WITH SPECIAL EMPHASIS ON RARE EARTH ELEMENTS (REE)

Issue

Critical raw materials are driving some of the biggest advancements in technology and energy efficiency in the world today, and the demand for them is growing rapidly. For example, the demand for rare earth elements (REE) and yttrium (Y) has grown because they have wide applications in defense (jet engines), energy (land-based turbines, fuel cells), telecommunication and elec-tronics (hard disk drives, flat-panel displays), transportation (automotive components), and other fields (chemical catalysts, medical applications).However, as demand grows, these resources have become scarce and expensive as their availability from conventional ores is exhausted. In the last 10 years, the importance of REE has been universally recognized also because of changes in supply and demand. A limited number of sources have a monopoly on the supply of these rare earth metals. For example, China now controls approximately 85 percent of world REE production. The United States imports more than 20,000 tons of REE a year, of which more than 90 percent comes from China. These factors have initiated a global “treasure hunt” that has bolstered explo-ration for new sources, particularly for REE.

Objective

The overall objective of this project is to develop methodologies to identify potential targets for REE recov-ery from the coal value chain. To address this main objective, the more specific goals of this project are to: 1) Determine REE content in Indiana coals and identify coal beds that have highest REE concentrations. Although REE will be the critical elements of particular interest in this project, other elements such as aluminum, phosphorous, uranium, titanium, manganese, gallium, germanium, cobalt, and others will also be examined. These elements are included for bolstering our predictive tools such as principal component analysis, which will allow future explorations for REE to use less expensive methods to locate potential REE resources. 2) Evaluate the distribution of REE in various fractions generated by coal preparation plants: coarse re-fuse, fines, clean coal. The coarse refuse will be of special interest because REE concentrate in min-eral fractions. We expect that coarse refuse from coals having high REE contents as established in point 1 could be targets for REE recovery. 3) Investigate REE concentration in pulverized rejects from power plants and fly ash and bottom ash generated from Indiana coals. Because, as mentioned above, REE are dominantly associated with mineral fractions, they are concentrated in the mineral and glass phases of coal ashes. Special effort will be put into obtaining coal ash from the coals of increased REE concentrations, as established in point 1; 4) Assess REE potential in acid-mine drainage (AMD). AMD contains REEs in dissolved form, making them less expensive to process although concentrations are much lower than in raw coal material or coal combustion concentrates. Preliminary data suggest a strong correlation of REEs to aluminum and magnesium in AMD, indicative of a noncoal detrital clay association, which becomes soluble under acidic conditions. 5) Based on 1–4, identify set of geological/chemical attributes that can be used as proxies for “sweet spots” for REE. We will use selected statistical methods, for example, principal component analysis (PCA) to identify associations of REE with other elements, coal properties, geographic location, etc. These attributes will be used as a predictive tool for elevated occurrences of REE and ultimately will help to delineate best targets for future recovery.

Contact: Tracy Branam (tbranam@indiana.edu)



StateMap 2021 Program

Issue

Objective

Create new maps that include: 1) bedrock mapping in the southern half of the Bedford quadrangle in south-central Indiana, 2) bedrock mapping in northern half of the Madison, Falmouth, and Louisville quadrangles in southeast Indiana, and 3) unconsolidated mapping of ice-marginal sediments between the cities of Jasper and Washington in south-central Indiana

Contact: DeAnn Reinhart (dsreinha@indiana.edu)