Impact of the COVID-19 Pandemic on the Minerals Sector: A Real Time Survey

Through the implementation of an online survey, run at the end of April 2020, researchers at the Irish Centre for Research in Applied Geosciences (iCRAG) explored the immediate effects of the COVID-19 pandemic on the minerals sector workforce. With more than 1,000 respondents, the survey provides insights into the impact of an unprecedented global event at a crucial point in its development. Seven weeks after the World Health Organization’s declaration of the pandemic, 65% of survey respondents agreed that COVID-19 had a significant impact on their work. Overall, 32% of respondents had experienced negative impacts on their employment, having either lost their jobs or been furloughed/temporarily laid off, or were working reduced hours. Geographically, the greatest impact on employment was in Africa, where 45% of respondents suffered negative effects. More often, younger respondents (ages 18–30) reported lost jobs (14%) whereas older survey participants reported working reduced hours (21%, ages 46–60). Respondents working in mineral exploration were most affected (40% suffered negative job impacts), but the impact across base, industrial, and precious metals was broadly similar for all participants; government employees were least affected but were not immune (10% on reduced hours). The level of concern about future job security due to the COVID-19 crisis varied, with 35% of respondents being more or very concerned or having already lost their jobs, 43% had little or no concern, and 22% were moderately concerned. The survey captured the experiences and perceptions of individual workers, providing a perspective different from information available in corporate statements and official statistics.

Management of Copper Heap Leach Projects: A Geologist’s Perspective

Editor’s note: The Geology and Mining series, edited by Dan Wood and Jeffrey Hedenquist, is designed to introduce early-career professionals and students to a variety of topics in mineral exploration, development, and mining, in order to provide insight into the many ways in which geoscientists contribute to the mineral industry. Abstract Copper production by heap leaching, coupled with solvent extraction and electrowinning (SX-EW), is a well-established technology, with an annual output of about 3.7 million tonnes (Mt) of copper metal. Ores presently amenable to copper heap leaching include copper oxides and secondary copper sulfides. Most copper deposits amenable to acid sulfate heap leaching result from supergene processes within porphyry copper systems, although copper heap leaching has been applied to sandstone and shale-hosted deposits, among others. Copper heap leaching is a rate-dependent process sensitive to copper mineralogy (copper oxides > secondary sulfides > hypogene sulfides), driven by the pH of the leach solution, the activity of ferric iron (Fe3+ (aq)) dissolved in the leach solution, and temperature. Acid consumption, a principal operating cost item, depends on the pH of the leach solution; the presence of reactive gangue minerals, notably carbonates, Ca plagioclase, pyroxene, Fe-rich amphibole, and olivine; and the cumulative surface area of material in the heap. There are three basic approaches to commercial copper heap leaching—run-of-mine, dedicated pad, and on-off pad leaching, with variables that include crushing, acid/ferric agglomeration, solution application rate, and leach solution pH. These approaches affect copper leach kinetics, overall copper recovery, acid consumption, and capital and operating costs. A successful copper heap leach evaluation program requires a systematic approach, beginning with geologic mapping, then drilling and hydraulic and metallurgical testing, and concluding with financial analysis, engineering, and permitting. As geologists are the unique party in the process, with a thorough understanding of the overall deposit geology, including ore and gangue mineralogy, the domains that comprise the deposit, and the geochemistry of leaching, they must remain fully involved in the project throughout the evaluation. At the outset, geologists must manage the drilling program and define the grade-mineral domains. Later, they must participate in the metallurgical and hydraulic testing programs, including the evaluation of test results; then, during financial modeling, they must collaborate with all of the other specialists.

COVID-19 and the Global Mining Industry

The world is currently experiencing a rapid and deep economic slowdown as a result of COVID-19 mitigation efforts. The depth and global nature of this recession, which could turn into a depression, suggests that this pandemic will significantly affect the demand for metals and the global mining sector. The majority of governments consider mining to be essential, meaning that the effect of mitigation on the mining industry and on metal production has been minimal to date. However, increases in metal stocks and decreases in metal prices suggest that the mining industry will be negatively affected by the COVID-19 crisis, at least in the short term. This paper presents an overview of the effects of COVID-19 mitigation on the mining sector to date. That includes variations in metal and commodity prices and stocks during the crisis and the outlining of two possible scenarios for COVID-19 related impacts. The first involves persistent supply-chain disruptions, where metal supply is restricted by logistical or COVID-19–related mitigation impacts on intermediates such as smelters and refiners. This restriction of supply could cause higher metal prices but also could cause issues with demand for ores and concentrates that negatively affect individual mining operations. More likely is a second slower demand growth scenario in which a global decrease in demand for metals causes further lowering of metal prices with associated negative economic impacts on mining operations. However, further research into global metal supply chains and the impact of the COVID-19 crisis on individual metals is needed. Key remaining unknowns include the influence of mitigation efforts on global metal supply and demand, the effect of these efforts on metal prices, and the geography of supply chains.

Importance of Geology in Cave Mining

Editor’s note: The Geology and Mining series, edited by Dan Wood and Jeffrey Hedenquist, is designed to introduce early-career professionals and students to a variety of topics in mineral exploration, development, and mining, in order to provide insight into the many ways in which geoscientists contribute to the mineral industry. Abstract Cave mining methods (generically referred to as block caving) are becoming the preferred mass underground mining options for large, regularly shaped mineral deposits that are too deep to mine by open pit. The depth at which caving is initiated has increased over the past few decades, and operational difficulties experienced in these new mines have indicated the need for a much improved geologic and geotechnical understanding of the rock mass, if the low-cost and high-productivity objectives of the method are to be maintained and the mines operated safely. Undercuts (the caving initiation level immediately above the ore extraction level) are now being developed at depths of >1,000 m below surface, with the objective of progressively deepening to 2,000 and, eventually, 3,000 m. Many of the deeper deposits now being mined by caving have lower average metal grades than previously caved at shallower depths and comprise harder and more heterogeneous rock masses, and some are located in higher-stress and higher-temperature environments. As a result, larger caving block heights are required for engineering reasons; mining costs (capital and operating) are also escalating. In these deeper cave mining environments, numerous hazards must be mitigated if safety, productivity, and profitability are not to be adversely affected. Fortunately, potential hazards can be indicated and evaluated during exploration, discovery, and deposit assessment, prior to mine design and planning. Major hazards include rock bursts, air blasts, discontinuous surface subsidence, and inrushes of fines. These hazards are present during all stages of the caving process, from cave establishment (tunnel and underground infrastructure development, drawbell opening, and undercutting) through cave propagation and cave breakthrough to surface, up to and including steady-state production. Improved geologic input into mine design and planning will facilitate recognition and management of these risks, mitigating their consequences.

SEG Newsletter 119 (October)

This file includes the entire issue in PDF format. The HTML versions of the peer-reviewed articles must be viewed and/or purchased separately.

Mine Planning and the Crucial Role of Geology

Editor’s note: The Geology and Mining series, edited by Dan Wood and Jeffrey Hedenquist, is designed to introduce early-career professionals and students to a variety of topics in mineral exploration, development, and mining, in order to provide insight into the many ways in which geoscientists contribute to the mineral industry. Abstract Mine planning is the process that determines the way in which an ore deposit will be mined over the life of a mining operation. It necessarily draws on everything that planning engineers believe will determine the ultimate success of the proposed mine and uses as its foundation all of the geology-related data on the deposit. It is both a strategic and a tactical process that first considers a longer-term horizon based on strategic considerations, followed by more detailed shorter-term planning processes, in this order; the latter are the result of tactical considerations. This structured process may also be referred to as integrated mine planning, and it is driven by a broader corporate strategy or set of objectives. As such, it is much more than the mining engineering section of the mine development process. It has to include inputs from all related disciplines, by combining all of the measured properties of the deposit with mining-associated parameters. This results in the planning process incorporating a significant number of interrelated parameters. If these parameters are not used diligently and accurately or are not well aligned, or if the underlying data are deficient in either quantity or quality, the project or operation is unlikely to achieve its potential, by virtue of failures in the planning process. Best-practice integrated planning incorporates relevant inputs from all mining-related fields: geology, geotechnical, geochemical, hydrogeological, hydrology, mining operations, minerals processing, marketing of product, waste management, tailings, environmental, social science, mine closure, etc. It includes all interfaces in the business-value driver model, from exploration drill holes to the mine closure plan. The planning process cannot be completed successfully by mining engineers working in isolation from professionals in other key disciplines. Because geology provides the foundation on which the mine plan is built, the quality and accuracy of the geologic data provided to planning teams by exploration geoscientists is crucial.

The Origin of the Porphyry Deposit Name: From Shellfish, Tyrian Purple Dye, and Imperial Rome to the World’s Largest Copper Deposits

The porphyry deposit name has a long and fascinating etymological history of over 3,000 years. “Porphyry” is derived from the ancient Greek word porphyra (πoρϕύρα), or purple. It was originally applied to a rare purple dye, Tyrian purple, extracted by the Phoenicians from murex shells. It was later applied to a prized purple porphyritic rock, Imperial Porphyry or Porfido rosso attico, quarried by the Romans from Mons Porphyrites in the Eastern Red Sea hills of Egypt from the first to fifth centuries A.D., and used as a monumental stone in Imperial Rome and Byzantium (Istanbul). The name evolved in the field of igneous petrology to include all rocks with a porphyritic texture, regardless of their color. Mining of the first porphyry copper deposits, which were originally called disseminated or low-grade copper deposits, started in 1905. As a result of the close spatial and genetic relationship to porphyry stocks, they became known as porphyry copper deposits. The term was first used by W. H. Emmons in his 1918 textbook The Principles of Economic Geology, but it was originally used more as an engineering and economic description, as in Parsons’ 1933 book The Porphyry Coppers. It was slow to catch on in the geological literature. It was first used in the title of a paper in Economic Geology in 1947 but did not gain widespread use until the 1970s, following the publication of seminal papers on porphyry models and genesis by Lowell and Guilbert (1970) and Sillitoe (1972, 1973).

SEG Newsletter 118 (July)

This file includes the entire issue in PDF format. The HTML versions of the peer-reviewed articles must be viewed and/or purchased separately.