South Africa is endowed with a wealth of coal-fired power stations that can produce extremely high volumes of fly ash per year exceeding 34 million tonnes. The use of high-volume fly ash (HVFA) binders in the construction sector has the capacity to significantly reduce greenhouse gas emissions associated with traditional cement production and offset the carbon footprint of Eskom. The excessive production of fly ash by Eskom warrants the need for developing ultra-high-volume fly ash binders (UHVFA, fly ash/binder > 60 wt%). Nonetheless, fly ash (FA) replacement of cement is still largely limited to 35% regardless of more ambitious research indicating the potential to surpass 60%. In view of the urgent need for South Africa to offset and reduce its carbon footprint, this work reviews and summarises the literature on the performance of HVFA binders with a focus on two specific areas: (i) strength and (ii) durability. On HVFA binder strength, the focus is drawn on work that analysed the compressive strength, flexural strength, and split tensile strength. This review focuses on the extant literature analysing the durability of HVFA binders using various tests, including sorptivity, resistivity, permeability, tortuosity, rapid chloride penetration tests, resistance to sulphate attack, and microstructural analysis. As the FA content increases towards optima, i.e., 50–80%, the most indicative composite characteristics of the strength and durability properties are UCS (30–90 MPa) and permeability (low). This review reveals the leading methodologies, instrumentation, findings, challenges, and contradictions.

This study examines the evolving study of mineral criticality and highlights a key gap: the limited involvement of experts from mineral-producing countries (MPCs), especially in the Global South. Bibliometric analysis of 101 critical minerals assessments and methodologies shows that the current criticality field of study reflects a narrow set of industrial priorities and risk perceptions, often framing MPCs’ development goals as supply chain risks. This phenomenon is referred to as ‘criticality provincialization’ in this paper. Findings suggest that mineral-consuming countries (MCCs) such as China and some Global North nations are moving away from country-agnostic criticality assessments and successfully localising the subject to their own realities. Together, they demonstrate that criticality is an important tool for asserting or defending a country’s manufacturing and industrial interests. The study reveals that the expert imbalance sustains foresight-driven policy in MCCs and reactive policy in MPCs, leading to long-term resource dependencies. Findings show that criticality designations typically exist parallel to a short-lived 3–5-year window of windfall resource rents for MPCs, which incentivises expanding mining operations but often fail to enable the development of downstream sectors. The study concludes that MPCs should adopt criticality as a field of study within mineral economics, build local expertise, and localise the concept to their own strategic, economic, and development priorities.

Fly ash (FA) from Eskom coal-fired power stations in South Africa is readily available. It is produced in more than 30 million tonnes annually. It presents a huge waste handling challenge and an opportunity for South Africa to offset it carbon emissions by developing and using Ultra High-Volume Fly Ash binders with FA content > 70%. The current study analyses peer-reviewed research articles on HVFA binders’ strength and durability using cooccurrence and bibliographic coupling of authors, institutions, countries, journals, and keywords using Covidence, Bibliometrix, and VOS viewer. Findings reveal that research efforts toward increasing fly ash dosages in HVFA binders remain significantly limited below 70%. HVFA binder strength and durability research depends on a nation’s coal consumption level and fly ash availability. Leading global coal consumers are also leading nations in HVFA binders’ research. Although South Africa is among the leading coal consumers and carbon emitters, it is ranked the least among nations contributing to developing high-strength and durability HVFA binders. The lack of research on HVFA binder strength and durability in South Africa calls for urgent scholarly efforts, given that findings from other nations and power plants cannot be generalised due to wide variations in fly ash characteristics within the same classes. The variations within same fly ash classes calls for further research to develop classification systems for HVFA binders’ development. Compressive strength and shrinkage were identified as the predominant properties of interest. The findings suggest that higher dosages of fly ash (FA) tend to reduce shrinkage. However, there are exceptions challenging this trend, underscoring the need for further research to address inconsistencies.

When an explosive detonates in a blasthole, approximately 20 to 30% of the energy is only utilized for fragmenting the rock mass whilst the bulk of the energy is lost in the form of ground vibrations, flyrocks and airblasts. Employees’ residences, mine offices, processing plants and engineering workshops built close to the mining area and are in danger of being damaged by blast induced hazards. In addition, due to flyrocks there was a high level of ore losses, ore dilution, equipment damages, mine roads and powerlines. To assess and reduce these negative impacts, monitoring of flyrocks, ground vibrations and airblast was carried out and generate a prediction model. A three-layer, feed-forward back-propagation of a 9-10-3 network architecture was trained, validated, and tested using the Bayesian regularization algorithm. A total of 100 monitored blast records obtained from the mine were used as input parameters for the ANN prediction model. Subsequently a Multivariate Regression analysis prediction model was run and used to compare with the results obtained from ANN model. Based on the study's findings, an ANN model proved to be the best for field predictions.To determine the relative impact of each input parameter on flyrocks, gound vibration, and Airblast, a sensitivity analysis was also carried out and lastly blast optimization which managed to reduce blast induced impacts by over 30%.

Asbestos mining in Zimbabwe left vast tracts of unrehabilitated land characterised by heaps of potentially carcinogenic tailings dumps. The research sought to trace the abandoned mines' environmental footprint, establish the tailings' tonnage, and explore the possibility of resuscitation against repurposing one of the prominent Gaths Mines for recovery of metals from the tailings. The mine has been under closure for two decades. the research findings indicated that over 2600km2 of land has potentially been contaminated by asbestos tailings within the abandoned Gaths Mines. The research concluded that resuscitating Gaths mines for asbestos extraction was not feasible given the international scrutiny on asbestos as a hazardous substance. However, after confirming that the Gaths mines hosts over 140 million tonnes of asbestos with 40.3% Mg content and traces of platinum group metals and Al among other recoverable metals, the research concluded that repurposing the site was feasible. The overall estimate for the capex for a 50 000t/pa Mg Plant 25-year project was estimated at US$416,7 million against an estimated net cash flow of US$1 billion. The NPV for the project was estimated to exceed US$95,5 million at a discount rate of 10%. The project’s Internal Rate of Return was estimated at 16.14%. Overall, the research concluded that the site can potentially be converted from a liability to a legacy that will transform the host communities toward the creation of a sustainable city in Mashava, Zimbabwe.