Thermodynamic Rarity and the Loss of Mineral Wealth

Abstract

The second law of thermodynamics and, specifically, exergy analysis have been traditionally used for the assessment and optimization of energy systems. Nevertheless, as shown in this paper, exergy could also constitute a powerful tool for the evaluation of mineral commodities. That said, new or re-defined exergy-based concepts need to be developed. This paper presents Thanatia as a baseline for evaluating the exergy of any mineral in the crust and opens the door to discuss the "thermodynamic rarity" concept as a basis for exergy analyses for mineral systems. Thermodynamic rarity is understood as the amount of exergy needed to obtain a given mineral from a completely degraded state, denoted as Thanatia. The rarer the mineral, the greater the associated exergy costs. It quantifies value, as it relates to concentration, chemical composition and cohesion, key aspects that determine whether a mine is exploitable. The theory further allows one to quantify the gradual loss of mineral capital on Earth as a consequence of "rarefaction processes" that occur at a mineral's end-of-life, when a commodity is wasted, and at its beginning-of-life, where mining ore grades decline after extraction.

Thermodynamic Approach to Evaluate the Criticality of Raw Materials and Its Application through a Material Flow Analysis in Europe

“…Thermodynamic rarity is defined as the amount of exergy needed to obtain a given commodity from an ordinary rock with prevailing technologies (Valero and Valero , ). In fact, exergy accurately measures, in energy terms, the distinction of a piece of matter with respect to a given reference environment, sometimes also known as the “dead state.” When dealing with mineral resources, this dead state is called Thanatia.…”

Thanatia: The Destiny of the Earth's Mineral Resources: A Thermodynamic Cradle‐to‐Cradle Assessment, by Antonio ValeroCapilla and Alicia ValeroDelgado. Hackensack, NJ, USA: World Scientific Publishing Company, 2014, 672 pp., ISBN 978‐981‐4273‐93‐0, hardcover, $158.00.

“…(Szargut ) for exergy evaluations of mineral resources can be difficult (Gößling‐Reisemann ). Further, when compared to fossil fuels, nonfuel minerals consistently have lower exergy values, resulting in wrong conclusions with regard to their value in the system analyzed (Gößling‐Reisemann ; Valero and Valero ).…”

“…The book by Valero and Valero provides a thorough summary of the authors’ pioneering work over several years using exergy as a measure in resource evaluations (Valero and Valero , ). The reader will be impressed by the breadth of the book, discussing in great detail the need for incorporating thermodynamics into resource evaluations, their idea of defining an alternative baseline environment (the Crepuscular Earth Model or Thanatia), and a thorough summary of data sources and assumptions made to obtain the energy replacement cost of important industrial minerals.…”

“…The chapters are based on numerous scientific publications published by the authors in recent years (e.g., Valero and Valero ; Valero et al. , ; Valero and Valero ; Valero et al. ).…”

Exergy Replacement Cost of Fossil Fuels: Closing the Carbon Cycle

“…Despite the fact that mineral deposits are said to exist (there are no viable resources) the baseline Thanatia assumes the concentration of the Earth's crust to be that of an average piece of bedrock. Valero and Valero's [5] concept is concerned with the amount of actual exergy needed to re-concentrate a mineral from Thanatia back to the conditions of the mine where it was originally found. As mineral deposits become exhausted, the exergy difference between a mine and the baseline reduces.…”