Steel Plant Wastes as a Resource of Rare Earth Elements and Rare Metals–Characterisation, Resource Estimation, and Economic Assessment

Abstract

Steel production results in a high magnitude of wastes that are either processed in the plant or sold for by-product generation due to stringent environmental regulations. Approximately 2-4 ton steel slag is generated per ton of crude steel by the steel plant. The major slags being highlighted are blast furnace (BF) slag, Linz-Donawitz (LD) slag, and Laddle-refining (LF) slag. As these slags are obtained primarily from the mixing of iron ore with coke and after a series of high-temperature reactions, metallization of some rare earth elements and rare metals is seen in these slags. This study is aimed to characterize these slag wastes generated from TATA STEEL, India, for the content of strategic and rare earth elements omnipresent by various tools like ICP-MS, SEM, and ED-XRF (equipped with Tornado analysis). BF slag is very rich in Ce (177 ppm), followed by 96 ppm La and 74 ppm Nd, apart from Cs (88 ppm), Sb (118 ppm), Sr (411 ppm), and Zr (337 ppm). Nearly 765 ppm V and 67 ppm Nb are reported in the LD slag. LF slag was analyzed with the presence of 66 ppm Ba, 96 ppm Sb, 48 ppm Nb and 70 ppm Cs. These low tenor raw materials owing to huge tonnage availability can serve as a viable secondary resource for utilization. They would be able to cater the critical metal demand ensuring a zero-waste process as per the economic analysis presented.