The Future of mining research in South Africa

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Created: Friday, 19 January 2024 11:55

Written by D.F. Malan

There is currently a flurry of bad news emanating from the mining industry. The electricity shortages, logistical problems, and low commodity prices have resulted in the proverbial perfect storm, and this is testing the resilience of our industry. As an encouragement to the readers affected, this is not the first time the industry had to survive exceptionally difficult periods. With ingenuity and a bit of luck, we always seem to pull through. For example, the gold price was artificially low in the 1960s owing to the London Gold Pool’s actions to defend the dollar price of $35 an ounce. Many of the marginal gold mining operations in South Africa had to close. The strong mining units survived, however, and they did exceptionally well in the 1970s during the gold boom that followed. Commodity prices will always be subjected to cyclic volatility, and we need to build our mining houses on solid rock to weather the occasional storm.
Part of building this resilience involves ensuring that we conduct the necessary research to improve our productivity and lower production costs. The Leon Commission of Inquiry into safety in the mining industry wrote in their 1995 report:

‘Furthermore, as no other region of economic significance has similar geometry, no mining industry outside South Africa pursues the solution to this problem. The platinum mines have essentially the same difficulty. The solution must therefore be found in South Africa.’

The key aspect is highlighted in bold, and we therefore need to foster mining research in South Africa. In terms of geometry, the Commission was referring to our tabular orebodies at a very flat dip with a small mining height. This makes mechanization extremely difficult, and it results in very high stress levels ahead of the mining faces in deep excavations. Furthermore, the decreasing extraction ratio of the shallow bord and pillar mines with increasing depth needs to be studied in detail and good solutions found. Multi-reef mining with a small middling between the reefs also requires further study. Unfortunately, the mining research capacity in our country has shrunk drastically over the last two decades. In his 2006 paper in this journal – Beyond Coalbrook: what did we really learn? – van der Merwe described the transfer of COMRO to the CSIR and the subsequent collapse of CSIR Miningtek.

‘Due to disillusionment and internal problems in the CSIR, there was an exodus of qualified and experienced researchers from 2003 onwards. It is estimated that in the period 2003 to 2005, an aggregate of over 1 000 years of research experience was lost. In retrospect, the collapse of Miningtek could well in future be seen as having a more severe impact than the collapse of Coalbrook.’

The situation has only become worse in the years following the publication of van der Merwe‘s paper. An innovative solution to this research challenge must be found and may in part lie with the small mining research groups that still survive at the tertiary institutions. Postgraduate students from industry are keen to do research and further their qualifications. A new ‘distributed research organization’, involving both industry and the universities, may therefore make a huge contribution to generating new knowledge. The mining industry and government must support and grow these mining departments. The current limited funding initiatives, unfortunately, seem to become increasingly complex, and simple ‘no-strings-attached’ support is required to enable the few surviving good researchers to focus on research only and to train the next generation of academics.

This edition of the Journal features several papers focusing on environmental and safety aspects in mining, and these are valuable studies for the South African industry. I congratulate the authors on their contributions to research.

D.F. Malan

Variety (at a high standard) is the spice of life

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Created: Friday, 08 December 2023 11:30

Written by R.M.S. Falcon

One of the aims that an Editorial Board of an internationally accredited journal (such as that of the SAIMM) aspires to achieve is to present to its readers novel, high-quality scientific and technological information. This requires papers submitted to the journal to be vigilantly reviewed and evaluated and, once published, assessed in terms of the citations arising from them. The number of citations affects the journal’s Impact Factor and related publishing evaluation norms. The Impact Factor of the journal in turn directly affects the professional standing of academics associated with the papers printed in that journal.

For a journal to be successful for all parties concerned, it is essential that it features only the highest level of research showing uniqueness, relevance, and previously unknown information.

However, there comes a time when young professionals, whether in their final years of study or early in their professional lives, are obliged to submit papers in order to build their own reputations and, more relevantly, to meet the requirements for graduation. For example, a doctoral student is required to publish at least two papers in an internationally accredited journal in order to be awarded his or her degree, while a master’s student is required to produce one such paper. The question then arises as to where to submit such papers for publication and whether the papers meet the journal’s publication criteria.

Given the high standards that journals set, and that senior students need to publish despite their limited experience or highly focused research topics, it is often difficult to reconcile these two requirements. However, the Editorial Board of this Journal believes it has found common ground in this dilemma by hosting an annual student conference at which senior students are invited to present their completed mining and metallurgical topics. From that event, the best papers are invited to be submitted for review. Once the papers have been reviewed and have met the criteria of the Journal they are selected for publication.

On this basis, the SAIMM Journal has, for many years, published one or more of its monthly editions featuring such top student papers. Readers will note the wide variation in topics and the nature of the research, all of which address issues of concern within the greater mining and metallurgical value chains worldwide.
In summary, may I refer to the previous month’s Commentary which called for industry to provide suitable research topics for senior mining and metallurgical students to undertake in order to meet the criteria for publication in journals such as this one.

The Editorial Board looks forward to many more student-based research papers in future, papers that will benefit the industries and communities in which the students are destined to serve and which will enhance the students’ own professional careers.

This month’s topics include an investigation of the ability of yielding rockbolts to resist multiple impact loads, which has considerable bearing on underground construction and safety. Research concerning the socioeconomic factors that influence women’s engagement on boards in the mining world led to significant recommendations based upon the findings. Another investigation found that the reduction of willemite in the presence of CaO showed considerable metallurgical benefit, with improved zinc extractions of up to 93%. In yet another paper a new model is presented for computing dimension stone operational costs during the cutting phase. This is significant as dimension stone is gaining rapidly in popularity because of its widespread use in construction.

R.M.S. Falcon

Student Edition

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Created: Thursday, 09 November 2023 11:11

Written by B. Genc

Welcome to another edition of papers for the Student Edition. Most of the papers published in this Student Edition are based on the annual Student Colloquium of 2022. The Colloquium, organised by the Southern African Institute of Mining and Metallurgy (SAIMM) since 2002, aims to identify the best final-year mining and metallurgical engineering students’ presentations. The papers presented at the Colloquium are based on the students’ final year projects. Our mining engineering students at Wits University, the School of Mining Engineering (Wits Mining) have a final-year course called Project Report, usually based on projects carried out by students on a mine during the vacation work session between the third and fourth year of study. It is a good opportunity for the students to showcase what they have learned during their summer vacation work. Wits Mining selects the top three presentations to take part in the Colloquium, similar to the other schools/departments in the country. The best performers amongst the participants were chosen by the panel of judges in the Colloquium and the winners were asked to prepare a paper to be published in the Journal of the SAIMM (JSAIMM). As with any paper submitted to the JSAIMM, the students’ papers are also subject to the Journal’s peer reviewing process.

In the last few years, the quality of the student papers submitted to the JSAIMM for publication has deteriorated, as most of them did not provide anything new. Novelty in a journal paper is essential. In order to address this, an initiative has begun with the help of the mining industry to realign the communication channels between the industry and academia. This initiative has a number of aims and objectives - one of which is to relook at the project topics given to the students; the project topics have a direct impact on the quality of the student report produced. Although it is still early days, this initiative has the potential to help generate more publishable papers in the JSAIMM. Further developments in this regard will be communicated to the SAIMM community.
In this Student Edition of the Journal, five papers have been selected, covering topics ranging from coal washability, contact sorption drying and real-time gypsum quality estimation in an industrial calciner. In addition, papers about electric-powered robotic subsea dredging crawler and electrical resistivity of heat-treated charcoal are some of the interesting reads.
Enjoy the October edition of the Journal!

B. Genc

A mineralogical phoenix rising out of the ashes …?

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Created: Tuesday, 17 October 2023 11:42

Written by S.O. Bada

In the last two centuries there have been significant changes in the way energy is generated. In countries that lack other natural resources such as hydropower, energy has traditionally been derived from solid, liquid, or gaseous fossil fuels. A mix of factors, including geological resources and technological advances, as well as political and economic pressures, has led to the selection of energy sources in each country. Over time, energy selection has been influenced by the availability of resources, the cost of production, and more recently by environmental impact.

In almost all of the world’s major industrialized nations, coal has been the primary source of power generation and a significant contributor to economic growth. But with the evolution of today’s complex energy mixes, the role of coal and its sister fossil fuels (oil and gas) is gradually changing. In the past two decades, the percentage of global energy produced from coal has decreased from 87% to 84%. Coal’s continued economic importance is due to its abundance, low cost, wide applications, and security of supply. The future role of coal will depend on a combination of factors, including mining pollution and the emission of CO2 and other greenhouse gases from coal-fired power generation. It is believed that these emissions have contributed to global warming and climate change, resulting in severe pressures from political and environmental quarters.

In recognition of its value in supplying safe, secure, and reliable energy, coal now needs to be used in a variety of clean coal processes as the world moves towards its Just Energy Transition. This approach has been taken widely by China and other countries in the Far East. No doubt South Africa will follow suit in due course.
However, the value of coal is now being recognized for a very different purpose. Coal is considered as an important source of carbon, rare earth elements, and related mineral-based commodities which are vital components in all high-tech, high-value advanced materials of the future. These include a range of products vital for use in the manufacture of renewable energy equipment.

This awakening to the new and alternative value of coal began in the USA and is now spreading globally, to the extent that coal is now regarded by some international bodies as one of the most valuable mineral commodities available. For these reasons, coal is now being termed in some quarters as ‘carbon ore’ and regional centres manufacturing high-tech high-value carbon-based products as ‘carbon valleys’, the equivalent of Silicon Valley in the USA.
Against this background, South Africa is now at an important crossroad.

On one hand, the country is undergoing a significant energy transition from coal to other sources of energy due to its commitments to meeting net-zero carbon emissions in the near future. On the other hand, a further and more innovative opportunity is now opening up for the use of coal in a highly efficient, responsible, and far more economically and nationally significant manner.

This new approach embraces a new coal-carbon value chain which, if followed, would lead to the development of new industries, increased employment opportunities, and the production of innovative products of considerable value in the fast-evolving world of modern construction, transport, and aerospace applications.
Such an approach would entail the recognition of coal as a high-value ‘carbon source’ yielding products of much greater value than simply producing a megawatt of heat or power that is gone in a flash. Furthermore, the use of carbon for production purposes would meet South Africa’s goal of capturing and use of carbon to achieve a low-carbon economy.

The US Department of Energy (DOE) has predicted that over the next 25 years, industries that manufacture coal-to-carbon products in coal mining communities could generate 280 000 to 480 000 jobs using low-skilled to highly skilled artisans. The DOE predicts that the global market for advanced carbon-based materials and products will reach over $96 billion this year. To give an example, Dialead carbon fibres from Mitsubishi Chemical Carbon Fiber and Composites USA are produced from a high-performance coal-tar pitch. The carbon fibre is being used to manufacture aircraft structural components, pressure vessels, wind turbine blades, and various items of sporting equipment, among other products.

With such expansion in this field, the American National Coal Council estimates that the tonnage of coal used in product manufacture has the potential to equal that utilized for power generation in coming years. In South Africa, a further benefit would be the dual use for coal being mined, namely full use of both the better grades for export, Eskom, or industry, and full use of lower grades for carbon-based products. The sources of the latter materials include coal fines, discards, coal tar pitch, and low-grade run-of-mine coal. Such precursors are the low-cost throw-away/discarded products of coal mining, and their use would also thereby serve the country’s interests in the circular economy as it applies to coal mining.

The forms of advanced carbon materials for which South African coals can be used include carbon fibre, carbon foam, graphene, carbon nanotubes, activated carbon, and coal composites. The expectation is that these will replace or complement conventional materials in the production of aerospace and electric vehicles, as well as in robotics and energy storage. In the latter scenario, carbon products will enhance the capacity and performance of lithium-ion batteries and be utilized to securely store and transport hydrogen in various forms.

At the University of the Witwatersrand and elsewhere, research and development is currently underway to establish South African coals as the source for advanced high-value products. This requires collaboration between all stakeholders (government, industry, research institutes, and others) to support this endeavour in order for the industry to reach its full potential. If successful, in due course South Africa could be the ‘Carbon Valley of Southern Africa’.
In these ways, the often-denigrated mineral called coal could become the bright and shining Phoenix of the mineral industry, literally rising out of the ashes.

S.O. Bada

To use/accept or not to use/accept AI, that is the question!

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Created: Tuesday, 03 October 2023 07:08

Written by R.M.S. Falcon

There is much interest in the fast-developing field of Artificial Intelligence (AI), and more particularly ChatGPT, in all sectors of the economy, not the least in education, editing, and publishing. A recent webinar presented by four informed speakers and hosted by ASSAf outlined some important issues, all of which are highly pertinent to the activities in our Institute. Most particularly, this would be of relevance for our Journal and the papers published therein. A few key points are outlined below, which I hope will lead to a discussion with respect to the way forward in developing the SAIMM’s Editorial Board’s (Publication Committee’s) future policy in this regard.
Of greatest significance is the fact that, while AI in the form of ChatGPT is fun, it is not an author! In the words of the publishers of Nature, while there may be a place for it in due course, it still has problems and will not meet the requirements of publishing norms today. The challenges include the facts that it cannot provide accuracy or interpretations and explanations, it cannot be held accountable, nor can it ensure data privacy. Furthermore, it takes information or ‘learns’ from previously published data and may therefore be biased in its output. It does not have the capacity to evaluate the information so extracted. In other words, input affects output.

What AI can do with the ‘tools’ now available is background research in an extensive and thorough manner, incorporating data from all sources taken from all levels and from different qualities of papers. In such cases it is necessary to recognize that the information so derived may be biased and that, more significantly, it cannot be defended. Who is accountable for such output? Thus, while AI is useful in communicating science it may not be able to contextualize the information. It may also be adept at summarizing data for lay audiences, but it could use unreviewed material and thereby provide misinformation. AI can improve the detection of plagiarism and manipulation of illustrations.

For these reasons, AI is useful in the early stages of research. It can write an article, write purpose statements, retrieve associated references, and obtain information from the literature. Furthermore, it can analyse results.

But such abilities also raise questions.

Can reviewers use AI to peer review a paper and then use the outcome as their own work? This is not possible  due to the depth of evaluation required as such tasks require human interpretation.

Can AI be considered a co-author when paired with genuine human authors? I have had sight of such a paper submitted to another journal, and wondered what our Editorial Board would do in such a case. A team of publishing editors agreed that AI could not be considered an author as it cannot meet the rules and requirements of journals.

The answers to date have been that all authors must be active, responsible, reliable, and able to defend their stance or statement, which humans can do but AI cannot. The recommendation in this instance is for AI to be cited in the acknowledgements, with a clear explanation as to its role in the paper. However, this is not always followed. Papers are being submitted with the bulk of the work produced by AI. The validity of such a paper without clear definition of the role played by AI is unacceptable.

Questions are now being asked as to whether there are guard rails to protect against such practices. Authors are asked to take responsibility and adopt ‘best practice’; namely, to practice and clearly show transparency and accountability. All this leads to the ultimate question: Does AI diminish scholarly publishing? The discussions continue.

R.M.S. Falcon

Copper Cobalt Edition July 2023

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Created: Monday, 11 September 2023 13:56

Written by K.C. Sole

The African Copperbelt, which stretches some 500 km in length, roughly following the northwest–southeast border between the Democratic Republic of Congo (DRC) and Zambia, contains more than 10% of the world’s known copper deposits, and hosts the highest concentration of industrial activity in sub-Saharan Africa outside of South Africa.

In 1867, Scottish missionary and explorer David Livingstone first described the smelting of ore into copper ingots by people living in the Katanga area, who had
known and worked the deposits for centuries. Formal exploitation in the DRC (then Belgian Congo) began when the railway line reached Elizabethville (now Lubumbashi) in 1910, under Union Minière du Haut-Katanga (which was nationalized in 1967 as Gécamines, La Générale des Carrières et des Mines). During the early 1930s, this was the largest copper-producing company in the world. Commercial copper mining in Zambia started in 1909 at Broken Hill, Northern Rhodesia (now Kabwe, Zambia). However, exploitation of these ores has long been one of the most complicated geopolitical and economic questions of the region, not only because of colonial (and later nationalistic) rivalries, but also because of the energy-intensive requirements of smelters—pyrometallurgical processing then being the only known technology for treating copper ores.

The first hydrometallurgical operation, comprising leaching and direct electrowinning, started up at Jadotville (now Likasi) in 1929, producing 30 kt/a of copper cathode. This technology could be economically operated at smaller scale, with a lower energy requirement, and in a less technically demanding environment than the traditional pyrometallurgy route. The Luilu operation started in 1960, with leaching and electrowinning for 150 kt/a copper production, as well as producing cobalt metal. Hydrometallurgical processing of copper oxide ores took a major step forward when the inclusion of a solvent extraction step prior to electrowinning was proven at the Tailings Leach Plant (now Konkola Copper) in Zambia in the 1970s. This technology allowed much higher cathode purity to be obtained than could be achieved by pyrometallurgical processes at that time.

Much of the latter part of the 20th century was characterized by rises and falls of the copper price, nationalization and denationalization of the mining industry in both countries, brutal civil wars, assassinations, abrupt changes of governments, many decades of political and economic instability and corruption, and the DRC falling to rank among the poorest countries in the world. Some stability was finally restored to the region in the early 2000s, prompting a cautious return of investment and industrial activity.

In the past 15 years, the DRC has experienced a huge resurgence of activity, with an impressive proportion of the capital spending, project development, operational expansions, and metal value production in the Southern African mining industry now located in this region. The geology and mineralogy of the deposits differ significantly from those in other major copper-producing regions of the world, the ores often having very high grades as well as the presence of cobalt. Both mining and metallurgy present some unique difficulties, not only technical, but also with respect to logistics, supply chain, and legislative issues; however, the region is blessed with large resources of oxide ores, mainly at relatively shallow depths, and a young, ambitious, and eager-to-learn workforce.

The high-grade oxide ores have enabled relatively rapid construction, commissioning, and ramp-up of numerous Copperbelt hydrometallurgical operations in the past decade to produce London Metal Exchange Grade A copper cathode. There are now nearly fifty production sites in the DRC, where copper cathode output has grown from almost zero in 2008 to 1.77 Mt in 2022, and is anticipated to exceed 2.50 Mt by 2025. More than 70% of the world’s recent new projects are in the DRC, accounting for more than 90% of new copper cathode capacity. Earlier this year, the DRC overtook Chile as the leading global producer of hydrometallurgical copper.
Pyrometallurgical production has not been abandoned, however: Ivanhoe Mining is planning the first new smelter in several decades to treat concentrate at the giant Kamoa–Kakula project in the DRC, which is ranked as the world’s largest high-grade copper deposit. Zambian processing has traditionally also focused heavily on pyrometallurgical routes.

The DRC also produces almost 70% of the world’s cobalt. In the 1960s, the highest-quality cobalt cathode in the world was produced at the Luilu plant near Kolwezi (now Kamoto Copper), which hosted engineers from Japan and the USA who came to learn from the African operations. Today, cobalt production from this region has become highly emotive and politicized: some 20% of the country’s supply is sourced from artisanal miners (estimated to exceed 100 000 in the Kolwezi area alone), often working in highly dangerous conditions and employing child labour. Cobalt is an essential component in many formulations of lithium-ion battery cathodes, considered critical to a low-carbon future; however, the precarious nature of the supply chain is driving technological development towards elimination of cobalt from these batteries. Cooperation and good faith between governments, legislators, multinational mining companies operating in the region, and labour are required to ensure that this window of opportunity for cobalt is not missed.

Despite ongoing difficult environments in the Copperbelt mining industry, industrial investment in this region is accelerating, mainly driven by Chinese-owned companies. To supply energy and electrification requirements to meet global decarbonization and sustainability goals, demand for copper is predicted to increase by some 20% by 2030; estimated cobalt demand is somewhat lower. As a major producer of these critical and strategic metals, the African Copperbelt is now slowly positioning to regain some of its former glory as a technical leader and major player on the world mining stage.

Sources
Crooks, S., Lindley, J., Lipus, D., Sellschop, R., Smit, E., and van Zyl, S. 2023. Bridging the copper supply gap. https://www.mckinsey.com/industries/metals-and-mining/our-insights/bridging-the-copper-supply-gap Declercq, R. 2022. Katanga and the American world of copper: mechanization, vertical integration, and territorialization of colonial capitalism, 1900–30. Born with a Copper Spoon: A Global History of Copper, 1830–1980. Declercq, R., Money, D., and Frøland, H.O. (eds). UBC Press, Vancouver. pp. 253–273. Etheridge, L. Not dated. Copperbelt region, Africa. https://www.britannica.com/place/Copperbelt-region-Africa
Tinkler, O.S. and Sole, K.C. 2023. Copper solvent extraction on the African Copperbelt: From historic origins to world-leading status. Journal of the Southern African Institute of Mining and Metallurgy, vol. 123, no. 7. pp. 349–356.

K.C. Sole
Chair of the Organising Committee:
Copper Cobalt Africa 2023 (PhD, PrEng, FSAIMM, FSAAE)

The Value of Variety

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Created: Tuesday, 25 July 2023 09:09

Written by W.C. Joughin

This edition of the Journal contains five general papers on a variety of topics. Three of the papers deal with rock engineering issues, one deals with spontaneous combustion, and another with soiling of solar reflectors or heliostats. The three rock engineering papers each cover very different challenges faced by the mining industry.

Squeezing rock conditions occur when tunnels located in weak, ductile rock masses are overstressed. Unlike the strong, brittle rock masses typically encountered in deep South African gold mines, which fracture and burst when overstressed, these weaker rock masses deform excessively, resulting in gradual closure of the tunnels until they are no longer serviceable. Support needs to be designed to manage squeezing rock conditions without rockfall incidents, and to keep the tunnels serviceable. The paper on this topic represents an update of an earlier benchmarking exercise on squeezing ground management in Australian and Canadian mines, taking into account advancements in deformation monitoring technologies and the increased availability of yielding ground support elements. The authors provide practical guidelines for predicting the level of squeezing, selecting appropriate support systems, and rehabilitation.

Another rock engineering paper deals with pillar design in Himalayan rock salt mines. The authors describe a comprehensive field testing exercise using flat jacks to determine pillar stress.

Monitoring and predicting the performance (overbreak and underbreak) of open stopes is essential for minimizing dilution, ore loss, and disruptions to the mining cycle to ensure profitability. Most open stoping operations perform cavity monitoring surveys of all stopes. The paper on open stope performance describes an improvement on the classic empirical methods for predicting overbreak that includes prediction of underbreak. The method was developed using machine learning techniques.

Spontaneous combustion is a common problem in coal mines, which causes environmental and safety and health problem risks. Another paper deals with the potential for spontaneous combustion and ground reactivity in carbonaceous shales at an opencast iron ore mine, and highlights the importance of determining the properties of the carbonaceous shale.

The soiling of solar reflectors (heliostats) is perhaps an unusual topic for inclusion in the Journal. However, concentrating solar power (CSP) technology is likely to play an important role in the energy transition, particularly for energy-intensive industries such as smelting. This paper addresses the soiling rate due to dust from a ferromanganese smelter, and its effect on heliostat performance.

W.C. Joughin

Research on pillar strength

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Created: Friday, 30 June 2023 09:22

Written by D.F. Malan

This edition of the Journal is the first of a series of planned themed editions. The South African mining industry faces several engineering challenges and it is hoped that these themes will stimulate research and groundbreaking papers. The first of these challenges is to develop local pillar strength equations and pillar design methodologies for hard rock mines. The shallow chrome, platinum, and manganese mines in South Africa typically use mechanized bord-and-pillar mining layouts. The older operations are gradually increasing in depth and this adversely affects the extraction ratios. The available design methodologies and pillar strength formulae dictate an increase in pillar size and a decrease in extraction ratio with depth. As these mining operations are vital to the South African economy, it is critical to maximize the extraction ratios and to ensure that the orebodies are optimally exploited. For outsiders, it is therefore somewhat surprising to learn that the layout designs are still mostly based on the Hedley and Grant pillar strength formula, which was originally developed for Canadian uranium mines in the early 1970s. Since then, very little research has been conducted to develop reef-type specific pillar strength formulae for the hard rock mines in South Africa. Considering the importance of this aspect, it is remarkable that a dedicated research programme to address this issue was not established a long time ago.

In contrast, extensive research into coal pillar strength was conducted in the aftermath of the Coalbrook disaster in 1960. The famous Salamon and Munro power-law strength formula was the result of this research effort. Interestingly, the selection of a power-law equation was inspired by laboratory and underground experiments that were conducted much earlier in the 1940s and 1950s. These studies indicated that the strengths of square pillars of the same height vary as the square root of their widths. The strengths of pillars of the same width also vary in inverse ratio to their height. This was generalized by Salamon in a power-law formula with the familiar exponents α and β. These exponents were subsequently calibrated using a database of failed and intact pillars. For the hard rock strength formula, Hedley and Grant used the same references from the 1940s and 1950s, as well as Salamon’s work, to motivate the use of a power-law equation. It is not clear, however, if the calibrated exponents apply to the reef types in the South African mines. Almost no collapses have been reported in the Bushveld Complex mines using this pillar formula, except where weak clay layers were present. This may indicate that the current designs are possibly too conservative. It also presents a difficult problem to researchers, as a database of failed and intact pillars for bord-and-pillar layouts cannot be compiled. The statistical approach followed by Salamon to calibrate an empirical strength equation for coal can therefore not be replicated for hard rock. Attempts have been made to use small UG2 and Merensky Reef crush pillars for such an analysis, but most of these crush pillars are at a similar mining height, they are irregular in size, and it is difficult to classify them as failed or intact based on visual observations.

This special edition of the Journal is therefore a welcome addition to the available research literature on pillar strength and we thank the authors who contributed papers. The work includes interesting studies on the use of a limit equilibrium pillar model in a boundary element code, laboratory studies to calibrate these models, underground observations of pillar behaviour, the effect of confinement on pillar strength, and the effect of pillar shape. Professor John Napier made many of these studies possible with his TEXAN displacement discontinuity code, and the authors are deeply grateful for his contribution in this regard.

D.F. Malan

Lithium – Many metallurgical challenges

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Created: Monday, 29 May 2023 08:22

Written by M. Dworzanowski

About 40 years ago lithium was a metal of curiosity. Its production was limited due to limited demand. Lithium was only produced from spodumene concentrate. Then, of course, along came lithium-ion batteries. As the demand for lithium-ion batteries has grown exponentially, so has the need to extract lithium from different sources.

Lithium is the only metal for which production from naturally-occuring solutions is as important as production from hard rock deposits. Dissolved lithium occurs in brines across many parts of the world, in the form of lithium chloride, which has an extremely high solubility. The primary source is salar (salt lake) deposits in South America. Dissolved lithium also occurs in oil and gas field brines as well as geothermal brines. The most important form of hard rock lithium is spodumene (lithium aluminium silicate), with Australia being the leading producer.

The metallurgical extraction of lithium from these different sources poses many challenges. The most important point to remember, is that purity is king! Battery-grade lithium carbonate and lithium hydroxide require purities of >99.8% and >99.9% respectively. This places enormous demands on selectivity and purification during the processing of the various sources of lithium.

Let us start with lithum in brine. It is easy to imagine that because the lithium is already dissolved, a large part of the metallurgical work has already been done. Well, you would be mistaken. Unfortunately, all the various brines contain many impurities. When production of lithium from brine started in South America, evaporation ponds were (and still are) used to concentrate the lithium. The concentrated brine then reports to a lithium carbonate plant where a long sequence of purification steps leads to the production of battery-grade lithium carbonate.

The location and lower lithium concentration of oil and gas field brines as well as geothermal brines means that evaporation ponds are a non-starter. Over the last 5 years there has been a significant development of direct lithium extraction (DLE) technologies, using ion-sieve, ion exchange, or solvent extraction. These techniques allow the selective extraction of the lithium from the brine, and are followed also by a sequence of purification steps. DLE plants are in operation in China and there is one in Argentina. There are many DLE projects in development and its application looks promising.

The issue with extracting lithium from hard rock deposits is that it is very energy intensive. Crushing and grinding are required, followed by DMS and/or flotation, to produce a spodumene concentrate. The concentrate then requires calcining and roasting steps before leaching and purification. Alternative less energy-intensive options are being studied but their possible application is still on the horizon.

Production of waste streams is also an issue for lithium extraction. In the case of salars, the evaporation ponds produce huge stockpiles of sodium, potassium, magnesium, and calcium salts. There are no markets close enough for these salts. Hard rock lithium extraction produces DMS or flotation tailings, which require tailings dams. It also produces a sodium sulphate by-product for which there is not always a market. The beauty of DLE is that the waste product, brine minus most of the lithium, can be reinjected back into the brine reservoir.

Given the very stringent purity requirements for battery -lithium hydroxide, many lithium projects are considering the electrolytic production of lithium hydroxide from purified lithium chloride, which is based on the chlor-alkali process used for producing sodium hydroxide from sodium chloride. The problems with this approach are the significant energy consumption and the large volumes of concentrated hydrochloric acid by-product, for which there is not always a market.

In summary, lithium metallurgical extraction faces many challenges in terms of producing the required product purities for lithium batteries, reducing waste production, and also the reduction of carbon footprints.

M. Dworzanowski

Mining projects in the UK and the community

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Created: Friday, 21 April 2023 08:50

Written by D. Tudor

The three major mining projects currently under way in the UK involve rail, coal, and fertilizer. They are all at various stages of the project cycle.

HS₂, the controversial high-speed rail project, was originally envisaged to connect London to Manchester and Leeds via Birmingham by 2033. Economics and politics have had a major impact on the final cost – up from an initial £35 billion to over £100 billion, and on the final route – the Birmingham Leeds link has been scrapped. However, work goes on and HS2 has once again begun tunnelling under London after launching its third giant tunnel boring machine (TBM) near Euston station. Following a longstanding tradition of naming TBMs after women, members of the local community have selected the name ‘Lydia’ for the TBM. Lydia Gandaa is a former teacher at the nearby Old Oak Common Primary School and a founding member of the Bubble & Squeak social enterprise in the area. She is an active member of the local community, running after-school and holiday clubs at the Old Oak Community Centre.

The new coal mine in Cumbria is a project near Whitehaven that will produce 2.8 million tons of coking coal a year for steelmaking and create 500 new jobs. It was approved by the UK government in January 2023, despite objections from local, national, and global groups over its climate impact. The mine will emit about 9 million tons of greenhouse gases a year, equivalent to putting 200 000 cars on the road. Most of the coal mined will be exported. The UK Climate Change Committee condemned the decision and said it contradicted the global effort towards net zero. Climate campaigners have been denied the opportunity to institute a legal challenge against the government over its decision to grant planning permission for a new coal mine in Cumbria. The project was initially approved by Cumbria County Council in October 2020. West Cumbria Mining, the firm behind the project, promised to create 500 direct jobs and 1500 in the wider community.

The Woodsmith project is Anglo American’s new polyhalite fertilizer mine that is being developed in the northeast of England near Whitby. Polyhalite is a naturally occurring mineral that contains potassium, sulphur, magnesium, and calcium plus numerous micronutrients, making it an ideal natural fertilizer. The project is currently sinking two mine shafts over a mile deep near Sneaton, south of Whitby and a 37 km long tunnel to a processing area at Wilton on Teesside.

After an investment of £400 million in 2022, Anglo announced that the capital expenditure for this year will be £650 million and approximately £800 million per year for the following three years – a significant investment for the local area.
The project currently employs over 1650 people at its sites in Whitby, Teesside, and Scarborough, with the majority being from the local communities.

The Woodsmith Foundation is an independent charity funded by Anglo American and has recently awarded grants totalling almost £250 000 towards initiatives that will support local communities from Teesside to Scarborough.
Seventy organizations received grants from the Foundation to help them deliver a range of programmes. For example, Scarborough Pride will use their grant to offer meaningful support and activities for the LGBT+ community in the Scarborough Borough. The Loftus Town Council will use their grant to start a gardening club for residents.

So, mining and the community are inseparable. What happens when lithium mining starts in Cornwall will be another story!

D. Tudor