Decreasing ore grades in global metallic mining, a theoretical issue or a global reality?,

Mining industry requires greats amounts of energy to extract and process resources, including a variety of concentration and refining processes, which normally depend on the mineral extracted, the ore grade, economic issues and mining conditions, among other factors. Using energy consumption information, different sustainability issues can be addressed, such as the relationship with ore grade over the years, energy variations in electricity or fossil fuel use, etc. (Glaister & Mudd, 2010; Northey et al. , 2013). Therefore, analyzing the energy intensity use in mining could lead to progress towards a better sustainable industry and a better resource management. Numerous studies have focused on the energy consumption of mining projects, carrying out the analysis primarily in one single country or one single element (Mudd, 2007; Mudd, 2010). Nevertheless, the information obtained in this paper represents a new and more accurate approach. For the first time, the most important mines that extract economically important minerals from several countries have been studied. Mines that extract gold, copper, lead and zinc have been selected, trying to take into account those mining companies whose reports were more accurate and reliable. Data regarding ore mined and milled, contained mineral, average ore grade, energy use and waste rock has been compiled. Moreover, the evolution of the ore grade over the years has been analyzed for each mine as well as the dependency of the energy intensity according to the type of the mine and process. The relationship between declining ore grades, energy and production has also been studied. After analyzing the energy intensity use as a function of the ore grade, the main conclusion that can be drawn is that as the ore grade decreases in the mine, the total energy consumption per tonne of ore seems to increase as well as the diesel and electricity used. Additionally, underground mines are more energy consuming than open cut mines, and the process of each mine also has a big influence in the energy consumption pattern. Still, ore grade seems to be one of the most important factors affecting the total energy consumption in the mining industry. With the case of copper, the study shows that the average copper ore grade decreases over time, while the energy consumption and the material produced increases. Analyzing Chilean copper mines, the average ore grade has decreased approximately 28.8% in just ten years. In the case of energy consumption in those mines, there is a 46% increase from 2003 to 2013, while the increase of copper produced for that same period is 30%. This seems to be in accordance with the historical trends observed for other mines at global level. Decreasing ore grades is no longer a theoretical issue but a global reality caused by the increasing consumption of raw materials as demonstrated by the empirical and updated data presented here. It also entails increases in the amount of ore mined and energy intensity, enhancing environmental and social costs. As this is not a trivial matter, comprehensive studies should be carried out considering the scarcity of raw materials in the accounting systems to improve resource management and promote the sustainable use of natural resources. Glaister, B. J., & Mudd, G. M. (2010). The environmental costs of platinum–PGM mining and sustainability: Is the glass half-full or half-empty? Minerals Engineering, 23(5), 438–450. Mudd, G. M. (2007). Global trends in gold mining: Towards quantifying environmental and resource sustainability. Resources Policy, 32(1-2), 42–56. Mudd, G. M. (2010b). The Environmental sustainability of mining in Australia: key mega-trends and looming constraints. Resources Policy, 35(2), 98–115. Northey, S., Haque, N., & Mudd, G. (2013). Using sustainability reporting to assess the environmental footprint of copper mining. Journal of Cleaner Production, 40, 118–12

van der Waals epitaxy of monolayer hexagonal boron nitride on copper foil : growth, crystallography and electronic band structure

We investigate the growth of hexagonal boron nitride (h-BN) on copper foil by low pressure chemical vapour deposition (LP-CVD). At low pressure, h-BN growth proceeds through the nucleation and growth of triangular islands. Comparison between the orientation of the islands and the local crystallographic orientation of the polycrystalline copper foil reveals an epitaxial relation between the copper and h-BN, even on Cu(100) and Cu(110) regions whose symmetry is not matched to the h-BN. However, the growth rate is faster and the islands more uniformly oriented on Cu(111) grains. Angle resolved photoemission spectroscopy measurements reveal a well-defined band structure for the h-BN, consistent with a band gap of 6 eV, that is decoupled from the copper surface beneath. These results indicate that, despite a weak interaction between h-BN and copper, van der Waals epitaxy defines the long range ordering of h-BN even on polycrystalline copper foils and suggest that large area, single crystal, monolayer h-BN could be readily and cheaply produced

Future Availability of Non-renewable Metal Resources and the Influence of Environmental, Social, and Governance Conflicts on Metal Production

Metal mining provides the elements required for the provision of energy, communication, transport and more. The increasing uptake of green technology, such as electric vehicles and renewable energy, will also further increase metal demand. However, the production lifespan of an average mine is far shorter than the timescales of mineral deposit formation, suggesting that metal mining is unsustainable on human timescales. In addition, some research suggests that known primary metal supplies will be exhausted within about 50 years. Here we present an analysis of global metal reserves that suggests that primary metal supplies will not run out on this timescale. Instead, we find that global reserves for most metals have not significantly decreased relative to production over time. This is the result of the replenishment of exhausted reserves by the further delineation of known orebodies as mineral exploration progresses. We suggest that environmental, social, and governance factors are likely to be the main source of risk in metal and mineral supply over the coming decades, more so than direct reserve depletion. This could potentially lead to increases in resource conflict and decreases in the conversion of resources to reserves and production

Increasing mine waste will induce land cover change that results in ecological degradation and human displacement

Highlights Mining-induced displacement is a severely under researched social policy problem. Through global data sources and historic remote sensing we analyze this problem. The main output of most mining activity is hazardous waste. We confirm waste as the principal source of human displacement globally in mining. Resources to fuel urbanisation and energy transition targets will drive increases in waste

Effect of oxygen and nitrogen functionalization on the physical and electronic structure of graphene

Covalent functionalization of graphene offers opportunities for tailoring its properties and is an unavoidable consequence of some graphene synthesis techniques. However, the changes induced by the functionalization are not well understood. By using atomic sources to control the extent of the oxygen and nitrogen functionalization, we studied the evolution in the structure and properties at the atomic scale. Atomic oxygen reversibly introduces epoxide groups whilst, under similar conditions, atomic nitrogen irreversibly creates diverse functionalities including substitutional, pyridinic, and pyrrolic nitrogen. Atomic oxygen leaves the Fermi energy at the Dirac point (i.e., undoped), whilst atomic nitrogen results in a net n-doping; however, the experimental results are consistent with the dominant electronic effect for both being a transition from delocalized to localized states, and hence the loss of the signature electronic structure of graphene

Heteroepitaxial growth of ferromagnetic MnSb(0001) films on Ge/Si(111) virtual substrates

Molecular beam epitaxial growth of ferromagnetic MnSb(0001) has been achieved on high quality, fully relaxed Ge(111)/Si(111) virtual substrates grown by reduced pressure chemical vapor deposition. The epilayers were characterized using reflection high energy electron diffraction, synchrotron hard X-ray diffraction, X-ray photoemission spectroscopy, and magnetometry. The surface reconstructions, magnetic properties, crystalline quality, and strain relaxation behavior of the MnSb films are similar to those of MnSb grown on GaAs(111). In contrast to GaAs substrates, segregation of substrate atoms through the MnSb film does not occur, and alternative polymorphs of MnSb are absent

Predicting the interactions between rivers and groundwater pumping

Abstract We summarise research that the eWater Cooperative Research Centre is carrying out incorporating groundwater-surface water interaction capabilities into the next generation of river management tools being developed for Australia's large river basins. We describe three simplified modelling approaches that are currently in development: (i) a reach scale 'Groundwater-Surface Water Link' model, which operates as a groundwater link to river models and accounts for interactions at the river-reach scale; (ii) a sub-reach scale 'Floodplain Processes' model, which dynamically models bank storage, evapotranspiration, and floodplain inundation. It enables more refined modelling of groundwater-surface water interactions, and can be linked to ecological response models; and (iii) a catchment scale model that estimates the surface and sub-surface flow components to streams

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy