The thermodynamic rarity concept: A systematic review

Abstract

Abstract The concept of thermodynamic rarity allows the assessment of the exergy needed to extract metals from common ores considering that mineral reserves have a significant exergy value. Estimates show that the reserves of some rare minerals may be exhausted in the next decades; this will cause a severe abiotic depletion that will make the production of certain commodities unfeasible and result in supply risks. This work presents the main scientific contributions to the evolution of the thermodynamic rarity concept, which began with the application of exergy analysis to the environmental-economic characterization of the minerals industry. The methodology used in this work is a longitudinal systematic review, considering the “research thematic area” and its subdomains. The search was performed in two large databases of scientific documents, Scopus and Web of Science. The results present the quantitative evolution of the main publications as well as a bibliometric analysis and a qualitative characterization of the contents of the main articles. The main period of this review was from 1983 to 2018, and it included 630 publications. The three main sets of keywords detected were a) “theory-of-exergetic-cost”; b) “exergy-replacement-cost”; and c) “thermodynamic-rarity”. The concepts that evolved to the idea of thermodynamic rarity during the period analyzed in the study are a) the theory of the Exergy Cost, suggested in 1986; b) the Concentration Exergy of minerals, elaborated in 2008; c) the Concentration Exergy Cost, of 2008; d) Thanatia, developed between 2008 and 2013; and lastly, e) the Exergy Replacement Cost (ERC), developed between 2008 and 2013, which represents the exergy needed to concentrate a mineral from the Thanatia state to the average concentration in a mine (mine state). The concept of Thermodynamic Rarity was published in a book in 2014 and in an article in 2015. It consists of the ERC plus the exergy needed to convert ore from the mine into a commodity. The thermodynamic rarity concept was used in 2017 in the proposition of the “Thermodynamic Criticality” and in 2018 as a method to assess the monetary losses caused by the inability to recover metals used in small amounts in vehicle recycling. In addition, in 2018 thermodynamic rarity was used to suggest specific recommendations in ecodesing.