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Primary mining of technology metal ores is needed to enable effective decarbonisation. The use of nickel in rechargeable batteries is expected to increase global demand for nickel rapidly over the coming years. Over 60% of annual global nickel production originates from nickel laterites, with Indonesia and the Philippines leading the market. Mining of nickel laterite ore can adversely affect the environment through the release of CO2 and potentially hazardous elements (PHE), such as hexavalent chromium, or asbestiform minerals. Through our better understanding of the social and environmental impacts of mining operations and the availability of technologies that can potentially mitigate adverse impact, it is paramount to aim for more responsible mining and metal recovery operations. This study focuses on the Sta Cruz nickel laterite deposit in the Philippines. Through a multi-scale and multi-technique analytical programme and drawing on existing knowledge1,2, we appraise the deposit holistically, focusing on (i) the geochemistry and mineralogy of major commodities and trace metals, such as the platinum group elements; (ii) carbonate forming metals, e.g. magnesium and (iii) the presence and ecotoxicity of PHE and minerals. We use this understanding to assess the potential for a circular economy in mining, via complete utilisation of the ore to maximise the metal output and minimise the waste produced. This includes the removal of CO2 through the formation of carbonate minerals (mineral carbonation). We also investigate the potential of carbonates to immobilise chromium crystallographically alongside the CO2. This aspect of mineral carbonation is currently poorly understood. We have carried out laboratory synthesis of chromium-doped carbonates at ambient P-T conditions, which indicates that the most common magnesium carbonates do not readily accommodate chromium. However, other carbonate-bearing minerals, including those belonging to layered double hydroxides, present more...

The six chemical elements referred to as the platinum-group metals (PGM) or platinum-group elements (PGE) are platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir) and osmium (Os). They are considered here with nickel because they commonly occur together in nature and PGM and nickel are extracted from the same ores in many deposits. more...

Cobalt is a lustrous, silvery-grey metal with many physical and chemical properties that make it useful in a wide variety of chemical and metallurgical applications (Petavratzi et al., 2019). In the UK cobalt is used in high-performance alloys for the aerospace sector and in the cemented carbide, magnet and special steel industries. Cobalt chemicals are used in the manufacture of batteries, glass and ceramics (Petavratzi et al., 2019). The UK imports cobalt in several forms, chiefly as unwrought metal. In 2017 the total apparent consumption of cobalt in the UK amounted to about 1500 tonnes of contained cobalt metal (Bide et al., 2019). more...

Graphite is a form of carbon that occurs as black to steel grey, lustrous flaky aggregates, disseminated in metamorphic rocks or as veins with a fibrous or foliated texture (Taylor, 1994). Natural graphite has a number of special properties, such as high electrical conductivity, a high melting point, resistance to corrosion and lubricity. Consequently it has varied industrial applications, including in electronics, lubrication, metallurgy and steel production (Robinson et al., 2017). In the UK graphite is used in aerospace applications, nuclear power generation and associated industries, in the petrochemical and automotive sectors, and for glass and steel manufacturing. Global natural graphite production in 2017 amounted to an estimated 1.2 million tonnes. more...

The rare earth elements (REE) are a group of 17 chemically similar metallic elements that include the 15 lanthanides, spanning atomic numbers 57 (lanthanum) to 71 (lutetium), together with scandium and yttrium. The REE are commonly divided into two groups: (1) the light rare earth elements (LREE), which include scandium and the elements lanthanum through to europium; and (2) the heavy rare earth elements (HREE), which include yttrium and the elements gadolinium through to lutetium. As refined metals the REE are typically lustrous, dark grey to silvery in appearance. more...

Lithium is a soft, silvery-white to grey alkali metal with a metallic lustre when fresh. It is highly reactive and in air quickly tarnishes to a dull silvery-grey and then black. Its physical and chemical properties make it useful in many chemical and metallurgical applications, for example lubricating greases, ceramics and glass, aluminium production and batteries. In the UK lithium is primarily used in the manufacture of lithium-ion batteries. The UK imports lithium in several forms, which include lithium carbonate, lithium oxide and lithium hydroxide. In 2017 the UK imported 1919 tonnes of lithium carbonate and a combined 324 tonnes of lithium oxide and hydroxide (Bide et al., 2019). more...

Deep-ocean mineral deposits could make a significant contribution to future raw material supply. Growing metal demand and geopolitics are focussing increasing attention on their resource potential and economic importance. However, accurate assessment of the total amounts of metal and its recoverability are very difficult. Deep-ocean mineral deposits also provide valuable windows through which to study the Earth, including the evolution of seawater and insights into the exchange of heat and chemicals between the crust and the oceans. Exploration for, and potential extraction of, deep-ocean mineral deposits poses many geological, technical, environmental and economic challenges, as well as regulatory and philosophical questions. Great uncertainty exists, and the development and stewardship of these deposits requires an incremental approach, encouraging transparency and scientific and civil societal input to balance the interests of all. more...

Marine ferromanganese oxide crusts (Fe–Mn crusts) are potentially important metal resources formed on the seafloor by precipitation of dissolved and colloidal components from ambient seawater onto rocky surfaces. The unique properties and slow growth rates of the crusts promote adsorption of numerous elements from seawater: some, such as Te and Co, reach concentrations rarely encountered elsewhere in nature. Consequently, Fe–Mn crusts are potential sources of metals used in technologies considered essential for the transition to a low-carbon economy. However, the precise distributions and metal concentrations of Fe–Mn crusts at regional and local scales are poorly constrained because of the diversity of geological, oceanographic and chemical processes involved in their formation. more...

Over the last decade there has been an increasing interest in deep-sea mineral resources that may contribute to future raw metal supply. However, before seafloor massive sulfides (SMS) can be considered as a resource, alteration and weathering processes that may affect their metal tenor have to be fully understood. This knowledge cannot be obtained by assessing the surface exposures alone. Seafloor drilling is required to gain information about the third dimension. In 2016, three extinct seafloor massive sulfide mounds, located in the Trans-Atlantic Geotraverse (TAG) hydrothermal area of the Mid-Atlantic Ridge were drilled. A mineralogical and textural comparison of drill core and surface-grab samples revealed that in recent ceased mounds high-temperature copper assemblages typical for black smoker chimneys are still present whereas in longer extinct mounds the mineralogy is pre-dominated by an iron mineral assemblage. Zinc becomes remobilized early in the mound evolution and forms either a layer in the upper part of the mound or has been totally leached from its interior. Precipitation temperatures of sphalerite calculated using the Fe/Zn ratio can help to identify these remobilization processes. While the Fe/Zn ratios of primary sphalerites yield temperatures that are in very good agreement with fluid temperatures measured in white smokers, calculated temperatures for sphalerites affected by remobilization are too high for SMS. Overall drilling of SMS provides valuable information on the internal structure and mineralogy of the shallow sub-surface, however, additional drilling of SMS, at a greater depth, is required to fully understand the processes affecting SMS and their economic potential. more...

The future extraction of deep-ocean mineral deposits depends on being able to recover the metals in an economic and environmentally sensitive way. Metal production is one of the most energy intensive industrial sectors. The characteristics of some deep-ocean mineral deposits permit them to be readily dissolved and to release their contained metals into solution. Current innovations in hydrometallurgy, including metal leaching with ionic liquids and solvent extraction in non-dispersive phase contactors, demonstrate how metals could potentially be extracted from Fe–Mn deposits with increased energy efficiency and a reduced environmental footprint compared with traditional processing techniques. The importance of biological processes in the formation of deep-ocean Fe–Mn deposits is poorly understood. However, understanding how microorganisms select and deposit metal ions could further enhance targeted extraction of ‘critical’ metals. more...

The decarbonisation of our energy supply is reliant on new technologies that are raw material intensive and will require a significant increase in the production of metals to sustain them. Ferromanganese (FeMn) crusts are seafloor precipitates, enriched in metals such as cobalt and tellurium, both of which have a predicted future demand above current production rates. In this study, we investigate the texture and composition of FeMn crusts on Tropic Seamount, a typical Atlantic guyot off the coast of western Africa, as a basis for assessing the future mineral resource potential of Atlantic Seamounts. The majority of the summit is flat and covered by FeMn crusts with average thicknesses of 3–4 cm. The crusts are characterized by two dominant textures consisting of either massive pillared growth or more chaotic, cuspate sections of FeMn oxides, with an increased proportion of detrital and organic material. The Fe, Mn, and Co contents in the FeMn oxide layers are not affected by texture. However, detrital material and bioclasts can form about 50% of cuspate areas, and the dilution effect of this entrained material considerably reduces the Fe, Mn, and Co concentrations if the bulk samples are analyzed. Whilst Tropic Seamount meets many of the prerequisites for a crust mining area, the thickness of the crusts and their average metal composition means extraction is unlikely to be viable in the near future. The ability to exploit more difficult terrains or multiple, closely spaced edifices would make economic feasibility more likely. more...

Certain metals that are vital for many modern technologies occur naturally in the Mourne Mountains Complex of County Down, Northern Ireland. These include niobium, tantalum and the rare earth elements. Using the Tellus geochemistry data and the results of more detailed sampling, we have investigated their geological sources in granite bedrock and their dispersion in stream sediments. From this research, an exploration methodology has emerged that can assist in the search for critical metals globally. Planned follow-on studies include investigations of the environmental fate of these metals and the potentially toxic elements with which they are naturally associated. more...

There is global concern about the availability of ‘critical’ metals: those of growing economic importance but vulnerable to supply shortage. Production from domestic resources could contribute to security of supply. However, we have little information on how critical metals are concentrated in the Earth’s crust and the resources that exist in the British Isles. Ireland’s diverse geology provides many geological environments in which critical metals may be enriched. This review considers mineral exploration potential for selected ‘critical’ metals identified by the European Commission and others considered important for high-technology applications. Known mineral deposits and the Tellus and Tellus Border geochemistry suggest that the north of Ireland is prospective for some of these metals and warrants further investigation. Extraction of these metals as by-products could facilitate the development of otherwise sub-economic ore bodies in Ireland, thus supporting economic growth. more...