The life cycle impact for platinum group metals and lithium to 2070 via surplus cost potential

© 2017 The Author(s)Purpose: A surplus cost potential (SCP) indicator has been developed as a measure of resource scarcity in the life cycle impact assessment (LCIA) context. To date, quality SCP estimates for other minerals than fossils are either not yet available or suffer methodological and data limitations. This paper overcomes these limitations and demonstrate how SCP estimates for metals can be calculated without the utilisation of ore grade function and by collecting primary economic and geological data. Methods: Data were collected in line with the geographical distribution, mine type, deposit type and production volumes and total production costs in order to construct cost-cumulative availability curves for platinum group metals (PGMs) and lithium. These curves capture the total amount of known mineral resources that can be recovered profitably at various prices from different types of mineral deposits under current conditions (this is, current technology, prevailing labour and other input prices). They served as a basis for modelling the marginal cost increase, a necessary parameter for estimating the SCP indicator. Surplus costs were calculated for different scenario projections for future mineral production considering future market dynamics, recyclability rates, demand-side technological developments and economic growth and by applying declining social discount rate. Results and discussion: Surplus costs were calculated for three mineral production scenarios, ranging from (US$2014/kg) 6545–8354 for platinum, 3583–4573 for palladium, 8281–10,569 for rhodium, 513–655 for ruthenium, 3201–4086 for iridium and 1.70–5.80 for lithium. Compared with the current production costs, the results indicate that problematic price increases of lithium are unlikely if the latest technological trends in the automotive sector will continue up to 2070. Surplus costs for PGMs are approximately one-third of the current production costs in all scenarios; hence, a threat of their price increases by 2070 will largely depend on the discovery of new deposits and the ability of new technologies to push these costs down over time. This also applies to lithium if the increasing electrification of road transport will continue up to 2070. Conclusions: This study provides useful insight into the availability of PGMs and lithium up to 2070. It proves that if time and resources permit, reliable surplus cost estimates can be calculated, at least in the short-run, based on the construction of one’s own curves with the level of quality comparable to expert-driven consulting services. Modelling and incorporating unknown deposits and potential future mineral production costs into these curves is the subject of future work

A collision-related pressure-temperature-time path for Prieska copper mine, namaqua-natal tectonic province, South Africa

Prieska Copper Mine lies in highly metamorphosed gneisses of the 1100 Ma Namaqua-Natal tectonic Province of South Africa, close to its boundary with the Kaapvaal Craton. The complex stratigraphy of the mining district is thought to have formed in a 1300 Ma arc environment, while the ore is regarded as a volcanogenic massive sulphide deposit. Petrographic study of key peraluminous and metabasic rock types led to the recognition of four principal metamorphic events M1-4 which, together with three deformation phases, constitute an orogenic cycle. Staurolite-garnet-kyanite M1 parageneses reflect medium pressure metamorphism, but are largely obscured by the dominant M2 muscovite-free, cordierite-garnetsillimanite assemblages. The latter reflect the metamorphic peak at about 730°C and 4.1 kbar, with partial melting suppressed by dry conditions. M2 peak temperatures at different localities within the 30-km-long mining district vary between 550 and 800°C, suggesting a localized heat source. M3 sillimanite-phlogopite grain boundary reactions represent a brief hydration event in P-T conditions close to those of M2. M4 parageneses which feature retrograde kyanite, staurolite, garnet, muscovite and chlorite are developed only in F3 shear zones, and represent a near-isobaric return to a geotherm close to that which prevailed during M1. P- T data for the metamorphic cycle is integrated with comprehensive geochronology to develop a model PTt path for the Prieska Mine region. The model envisages an orogenic cycle at the end of a 1300-900 Ma Wilson Cycle, characterised by collision, crustal thickening followed by a long period of uplift and erosion. The peak metamorphic conditions are ascribed to two short-lived, essentially contact metamorphic events, due to the intrusion of the Plat Sjambok Anorthosite Suite. The 400 Ma Wilson Cycle, 300 Ma orogeny and 0.05 mm/yr uplift rate envisaged for Prieska Mine are long and slow compared with Phanerozoic examples, however, similar parameters seem to characterize more than one Proterozoic event. © 1992.Articl

A collision-related pressure-temperature-time path for Prieska copper mine, namaqua-natal tectonic province, South Africa

Prieska Copper Mine lies in highly metamorphosed gneisses of the 1100 Ma Namaqua-Natal tectonic Province of South Africa, close to its boundary with the Kaapvaal Craton. The complex stratigraphy of the mining district is thought to have formed in a 1300 Ma arc environment, while the ore is regarded as a volcanogenic massive sulphide deposit. Petrographic study of key peraluminous and metabasic rock types led to the recognition of four principal metamorphic events M1-4 which, together with three deformation phases, constitute an orogenic cycle. Staurolite-garnet-kyanite M1 parageneses reflect medium pressure metamorphism, but are largely obscured by the dominant M2 muscovite-free, cordierite-garnetsillimanite assemblages. The latter reflect the metamorphic peak at about 730°C and 4.1 kbar, with partial melting suppressed by dry conditions. M2 peak temperatures at different localities within the 30-km-long mining district vary between 550 and 800°C, suggesting a localized heat source. M3 sillimanite-phlogopite grain boundary reactions represent a brief hydration event in P-T conditions close to those of M2. M4 parageneses which feature retrograde kyanite, staurolite, garnet, muscovite and chlorite are developed only in F3 shear zones, and represent a near-isobaric return to a geotherm close to that which prevailed during M1. P- T data for the metamorphic cycle is integrated with comprehensive geochronology to develop a model PTt path for the Prieska Mine region. The model envisages an orogenic cycle at the end of a 1300-900 Ma Wilson Cycle, characterised by collision, crustal thickening followed by a long period of uplift and erosion. The peak metamorphic conditions are ascribed to two short-lived, essentially contact metamorphic events, due to the intrusion of the Plat Sjambok Anorthosite Suite. The 400 Ma Wilson Cycle, 300 Ma orogeny and 0.05 mm/yr uplift rate envisaged for Prieska Mine are long and slow compared with Phanerozoic examples, however, similar parameters seem to characterize more than one Proterozoic event. © 1992.Articl

Applying the box plot to the recognition of footwall alteration zones related to VMS deposits in a high-grade metamorphic terrain, South Africa, a lithogeochemical exploration application

Alteration zones (more commonly foot wall alteration zones) are related to volcanic-hosted massive sulfide (VMS) deposits and represent unique features that may be targeted during exploration. Of these, the chloritic foot wall alteration pipe is the most extensive and characteristic of VMS deposits. This feature is geochemically identified by a strong relative enrichment in aluminium and magnesium and a coupled depletion in calcium and sodium, giving rise to chloritic rocks in the primary environment of formation. During high grade regional metamorphism such chloritic precursor rock types are replaced by an unusual mineral paragenesis, typically containing magnesium rich cordierite, phlogopite, orthoamphiboles or orthopyroxenes and aluminium rich minerals such as sillimanite and corundum. This suggests that the unusual geochemical features of the alteration zone, retained during the deformation and metamorphism, should be recognisable in lithogeochemical exploration. The massive sulfide deposit in the eastern part of the metamorphic Namaqua Province, South Africa, at Areachap, Kantienpan and the defunct Prieska Cu–Zn Mine are hosted by a Mid-Proterozoic volcano sedimentary succession known as the Areachap Group. These deposits were affected by a complex deformation and metamorphic history and represent examples of upper amphibolite to granulite grade metamorphosed VMS deposits. The application of the known lithogeochemical methods is especially complicated where the geology is not well understood, due to the poor rock exposure of complexly deformed and metamorphosed areas, such as in the eastern part of the Namaqua Province. The box plot presents a more readily applicable lithogeochemical method to characterize and identify the alteration process, but it was designed for relatively un-metamorphosed environments. It is demonstrated here that the box plot may also be applied to high-grade metamorphic terrains and that the mineral phases used in defining the boxplot in low grade metamorphic environments may be replaced by their equivalents in high grade metamorphic terrains. The compositional trends of the metamorphic minerals themselves may be used in defining the boxplot for high grade metamorphic terrains. These include the transition of: annite to phlogopite; grossular to almandine or pyrope, augite to enstatite or clinoenstatite, and hornblende to gedrite or cummingtonite. Close to the ore zone, the relative Mg content of pyroxene, cordierite and biotite are higher than further away from this zone. It could be demonstrated that the changes in the mineral compositions are gradational when comparing unaffected rocks with progressively more altered wall rocks. Conclusions based on an application of the isocon method demonstrate that primary footwall alteration zones in the Areachap Group's VMS deposits are characterized by elemental depletion of Na2O, CaO, Sr, Ni, V and La and enrichment of MgO, Fe2O3(total), S, Zn, SiO2, Co and F. It is shown that the whole rock compositions of rocks that were independently identified as the metamorphic equivalents of altered rocks, using the isocon method, plot in the correct place in the box plot for high grade regionally metamorphosed terrains. This establishes the box plot as an effective and practical tool for lithogeochemical exploration for VMS deposits in complexly deformed high grade metamorphosed terrains.Please see Appendix for supplementary dataPartly funded by CERMOD at the University of Pretoria.http://www.elsevier.de/chemernf201

Platinum Group Elements in the Uitkomst Complex, South Africa

The mafic-ultramafic Uitkomst Complex of South Africa is a tubular intrusion that is believed to be coeval and cogenetic with the 2054 Ma Bushveld Complex. It consists of a thin (3.5-m) basal gabbronoritic phase that is overlain by ca. 450 m of ultramafic rocks and 250 m of gabbroic and dioritic rocks. The basal 300 m of the intrusion hosts disseminated Ni-Cu-platinum group element (PGE) sulfides (100 Mt at ca. 0.55% Ni, 0.17% Cu). In addition, several lenses of massive sulfides (2.9 Mt at 2.04% Ni, 1.13% Cu, and 6 ppm total PGE) are situated in the immediate floor of the intrusion. We determined the PGE concentrations in 86 samples from the Uitkomst Complex. The rocks containing disseminated sulfides have up to 3 ppm total PGE and the massive sulfides have up to 7 ppm total PGE. Sulfide segregation was triggered by assimilation of external sulfur from the country rocks adjacent to the intrusion. The most important contaminant was probably dolomite of the Malmani Subgroup that includes sulfidic shale interlayers. The composition of the magmatic sulfides can be modeled by applying an R factor (mass ratio of silicate melt to sulfide melt) of between 800 and 1,000. The sulfides in the ultramafic rocks show little tendency of metal depletion with height and thus appear to have segregated from successive surges of fertile magma. This suggests that the basal portion of the Uitkomst Complex crystallized in an open magmatic system, e.g., a magma conduit. The gabbroic and dioritic rocks in the upper portion of the complex are relatively PGE depleted (Cu/Pd mostly higher than in primitive mantle), suggesting that they crystallized from the residual magmas to the ultramafic rocks in a closed magmatic system. Some of the ultramafic rocks in the central portion of the complex are S poor (mostly <700 ppb S) but contain relatively high amounts (30–250 ppb) of total PGE. These rocks have unusually low Pd/Ir (0.6–ca. 10), Cu/Zr (typically <0.5), and high Pt/Pd (up to 19), suggesting that either Pd, Cu, and S were remobilized or that the magma was undersaturated in sulfide liquid at the time the rocks formed and that platinum group minerals (PGM) crystallized. The present study suggests that sill-like bodies of Bushveld affinity that intruded dolomitic rocks may generally have an enhanced potential to host massive magmatic Ni-Cu-PGE sulfides