Content and Distribution of Transition Metals and Rare Earth Elements in Magnetically and Mechanically Separated Brown Coal Ash

Abstract

Coal ash is known to contain a noticeable amount of valuable elements, including transition metals and lanthanides. Therefore it is quite actual problem to extract them for metallurgy and other applications. This paper presents the results of high gradient magnetic and mechanical separation, microscopy, element analyses and optical spectroscopy of brown coal ash taken from the combustion camera and chimney-stalk of Angren thermal power station. The separated magnetic fraction was 3.4 wt.%, where the content of Fe in ferrospheres increased to 58 wt.%. The highest contents of Fe and rare earth elements were found in the fine fractions of 50-100 µm. Optical absorption spectroscopy of water solutions of the magnetic fractions revealed Fe 2+ and Fe 3+ions in the ratio of ~1:1. The separated coal ash could be used for cleaning of technological liquid waste by means of the high gradient magnetic field.

A Review of the Occurrence and Promising Recovery Methods of Rare Earth Elements from Coal and Coal By-Products

“…2 REE content in bottom ash from Malikov et al [53]. 3 REE content in fly ash form Malikov et al [53]. 4 REE content in fly ash from Blissett et al [13].…”

“…Figure 3 shows that samples with greater than 700 ppm REE on an ash basis are more uniformly distributed in coal basins of the United States compared with Figure 3a and Figure 3b shows that coals with high heavy rare earth (HREE) content are distributed in the Northern Appalachian and Central Appalachian basins. Overall, coal is a promising raw material for REE recovery and a number of studies have been initiated in this area [3,20,28,31,33,53]. However, most of these investigations simply focus on the characterization of REEs in coal with no effort to address the potential to recovery REEs from coal.…”