Rock-to-metal ratios of the rare earth elements

• Published in: Journal of cleaner production 2023-06, Vol.405, p.136958, Article 136958
• Main Authors: Nassar, Nedal T., Lederer, Graham W., Padilla, Abraham J., Gambogi, Joseph, Cordier, Daniel J., Brainard, Jamie L., Lessard, Joseph D., Charab, Ryan
• Format: Article
• Language: English
• Subjects: Critical minerals; Industrial ecology; Life cycle inventory; Mine waste; Tailings; Total material requirement
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2023.136958

The relative quantities of ore mined and waste rock (i.e., overburden) removed to produce the rare earth elements—their rock-to-metal ratios—were calculated for 21 individual operations or regions covering nearly all mine production in 2018. The results indicate that the rock-to-metal ratios for the total rare earth elements ranged from a low of 1.6 × 101 to a high of 3.6 × 103, with operations in Brazil and Russia having the lowest ratios and ion-adsorption clays operations in China and Myanmar having the highest. For comparison, the global average rock-to-metal ratio for the total rare earth elements (9.8 × 102) fell between that of cobalt (8.6 × 102) and tungsten (1.1 × 103). Driven by their relative abundance in the ore and unit prices that were used in the economic allocation of the environmental burdens, the global rock-to-metal ratio for individual rare earth elements was lowest for cerium (2.3 × 101) and lanthanum (7.7 × 101) and highest for dysprosium (1.7 × 104), terbium (3.7 × 104), and lutetium (6.4 × 104). Like the rock-to-metal ratios for the total rare earth elements, rock-to-metal ratios for individual rare earth elements varied by roughly two orders of magnitude among the various operations examined. An alternative perspective of only accounting for the overburden that is physically removed in ion-adsorption clays in-situ operations yielded global rock-to-metal ratios that were an order of magnitude lower or less for many of the rare earth elements. [Display omitted] •Rock-to-metal ratios (RMRs) of the rare earth elements were calculated for 2018.•Ce and La had the lowest RMRs at ∼101, while Dy, Tb, and Lu had the highest at ∼104.•RMRs for individual elements varied by two orders of magnitude across operations.