Decreasing Metal Ore Grades—Is the Fear of Resource Depletion Justified?

Rötzer, Nadine; Schmidt, Mario

doi:10.3390/resources7040088

Cited by 60 publications

(37 citation statements)

References 26 publications

(39 reference statements)

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“…This can be done by adjusting the ore grade. If, however, the mill head grade is used, which is often the basis for a discussion of the decreasing ore grades [12], dilution is already included. In this paper, we define the ore grade as the mill head grade, because it represents the average mined ore grade and is often referred to in publications.…”

Section: Miningmentioning

confidence: 99%

“…Even if rising demand is the driving force, it cannot be said with certainty that there will be mining of lower ore grades. There are still deposits with higher ore grades [12,51], although a decrease seems to be more likely since a higher demand offers potentials for economies of scale and further technological improvements [52,53].…”

Section: Future Developmentsmentioning

confidence: 99%

“…However, historical data show a decline in the ore grade of the mined material [10,11]. There are many reasons for this: for example, the enormous increase in demand and thus a change in the type of deposit mined as well as the development of the technologies used for extraction and production [12,13]. While this trend does not indicate a purely geological shortage, it is often interpreted as an indication that the availability of raw materials is limited.…”

Section: Introductionmentioning

confidence: 99%

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Historical, Current, and Future Energy Demand from Global Copper Production and Its Impact on Climate Change

Rötzer

Schmidt

2020

Resources

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Copper has always played an important role in human development. Demand for copper is going to rise, which makes its future supply a key issue for society. However, the oft-discussed declining ore grade and, therefore, the assumed enormous increase in energy demand and global warming potential could lead to a supply constraint. To develop suitable strategies to ensure copper availability, it is important to better understand the relationship between energy and ore grade and also its development. Therefore, in this paper we describe the development of the cumulative energy demand of copper production over the last eight decades and give an outlook into the future using a holistic process-based modelling approach. We also discuss how technological progress has thus far been able to offset the decreasing ore grade. However, if geological factors are becoming less favorable, technological improvements such as renewable energies are vital to keep this trend going.

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Section: Miningmentioning

confidence: 99%

Section: Future Developmentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Historical, Current, and Future Energy Demand from Global Copper Production and Its Impact on Climate Change

Rötzer

Schmidt

2020

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“…The problem with this approach, according to experts in the mining industry, is "that grades have so far been of limited relevance to the issue of availability" ( [16], Section 10). There are many different arguments for this statement (see also an analysis on this issue [23]).…”

Section: Resource Scarcity In the Classic Environmental Life-cycle Asmentioning

confidence: 99%

The Eco-Costs of Material Scarcity, a Resource Indicator for LCA, Derived from a Statistical Analysis on Excessive Price Peaks

2019

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The availability of resources is crucial for the socio-economic stability of our society. For more than two decades, there was a debate on how to structure this issue within the context of life-Cycle assessment (LCA). The classical approach with LCA is to describe “scarcity” for future generations (100–1000 years) in terms of absolute depletion. The problem, however, is that the long-term availability is simply not known (within a factor of 100–1000). Outside the LCA community, the short-term supply risks (10–30 years) were predicted, resulting in the list of critical raw materials (CRM) of the European Union (EU), and the British risk list. The methodology used, however, cannot easily be transposed and applied into LCA calculations. This paper presents a new approach to the issue of short-term material supply shortages, based on subsequent sudden price jumps, which can lead to socio-economic instability. The basic approach is that each resource is characterized by its own specific supply chain with its specific price volatility. The eco-costs of material scarcity are derived from the so-called value at risk (VAR), a well-known statistical risk indicator in the financial world. This paper provides a list of indicators for 42 metals. An advantage of the system is that it is directly related to business risks, and is relatively easy to understand. A disadvantage is that “statistics of the past” might not be replicated in the future (e.g., when changing from structural oversupply to overdemand, or vice versa, which appeared an issue for two companion metals over the last 30 years). Further research is recommended to improve the statistics.

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“…The experience over the last couple of centuries has been that new discoveries or increases in economic reserves have caused long-term average ore grades to decline. As technologies have changed, new economic reserves have been discovered and others extended to lower-grade zones resulting in declines in the average grade of ore that has been mined and processed (Rötzer and Schmidt 2018). The grade to volume relationship for individual porphyry copper deposits is exponential, which is also part of the reason why head grades are inversely related to the tonnage of ore mined (Crowson 2011a, Northey et al 2018) and ore grade declines have been accompanied by large increases in identified reserves.…”

Section: What Is Known?mentioning

confidence: 99%

Why current assessments of ‘future efforts’ are no basis for establishing policies on material use—a response to research on ore grades

Ericsson

Drielsma²,

Humphreys

et al. 2019

Miner Econ

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The concept of declining availability due to declining primary resource quality has been investigated for various resource categories to try to determine the effort needed in future to either extract the resource or to treat it for intended use. The concept of 'future efforts' due to declining primary resource quality is explored by Vieira et al. (2016. They suggest that a specific burden associated with the production of each primary material should be taken into account and that this can be done by studying the costs of production or ore requirements of the material and by projecting forward likely costs into the future. For the purpose of the analysis, they employ mine cost data for 2000-2013 and reserve data published by the US Geological Survey. We will argue below that this approach is not correct and, with this comment, we wish to make it clear that-contrary to what is suggested in much of the Life Cycle Assessment literature-the future efforts concept is not an established rule of natural resource extraction. For mineral resources, it is quite impossible to proceed with extraction in the ordered way that this approach suggests because nobody has a comprehensive view of the entire natural resource. Secondly, there is no evidence available to support the idea that extracting a mineral resource today causes a decrease in availability of that mineral tomorrow. On the contrary, the weight of evidence suggests that where declines in ore grades have been observed, they are overwhelmingly due to technology development in response to high demand and have been accompanied by increased mining efficiency and increased availability of the resource to successive generations. Grade is a rather arbitrary measure since the grade of mined ore ultimately has to do with the relationship of costs and revenues. It is not only the technology employed which matters but also how smartly this technology is applied. Thirdly, the future efforts approach entirely overlooks the potential availability of mineral materials from secondary (scrap) sources, sources which are expected to become increasingly important to mineral supply in the future. Our conclusion from the discussion is that we as humans have been able to economically access ever-increasing amounts of material from often lower and lower-grade sources. What is impossible to conclude from this is that the environment no longer contains any of the higher-grade sources. In fact, all the available evidence suggests that higher-grade deposits are still out there. We remain critical optimists.

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Decreasing Metal Ore Grades—Is the Fear of Resource Depletion Justified?

Cited by 60 publications

References 26 publications

Historical, Current, and Future Energy Demand from Global Copper Production and Its Impact on Climate Change

Historical, Current, and Future Energy Demand from Global Copper Production and Its Impact on Climate Change

The Eco-Costs of Material Scarcity, a Resource Indicator for LCA, Derived from a Statistical Analysis on Excessive Price Peaks

Why current assessments of ‘future efforts’ are no basis for establishing policies on material use—a response to research on ore grades

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