TY - JOUR A1 - Korges, Maximilian A1 - Junge, Malte A1 - Borg, Gregor A1 - Oberthür, Thomas T1 - Supergene mobilization and redistribution of platinum-group elements in the Merensky Reef, eastern Bushveld Complex, South Africa JF - The Canadian mineralogist N2 - Near-surface supergene ores of the Merensky Reef in the Bushveld Complex, South Africa, contain economic grades of platinum-group elements, however, these are currently uneconomic due to low recovery rates. This is the first study that investigates the variation in platinum-group elements in pristine and supergene samples of the Merensky Reef from five drill cores from the eastern Bushveld. The samples from the Richmond and Twickenham farms show different degrees of weathering. The whole-rock platinum-group element distribution was studied by inductively coupled plasma-mass spectrometry and the platinum-group minerals were investigated by reflected-light microscopy, scanning electron microscopy, and electron microprobe analysis.
In pristine ("fresh") Merensky Reef samples, platinum-group elements occur mainly as discrete platinum-group minerals, such as platinum-group element-sulfides (cooperite-braggite) and laurite as well as subordinate platinum-group elementbismuthotellurides and platinum-group element-arsenides, and also in solid solution in sulfides (especially Pd in pentlandite). During weathering, Pd and S were removed, resulting in a platinum-group mineral mineralogy in the supergene Merensky Reef that mainly consists of relict platinum-group minerals, Pt-Fe alloys, and Pt-oxides/hydroxides. Additional proportions of platinum-group elements are hosted by Fe-hydroxides and secondary hydrosilicates (e.g., serpentine group minerals and chlorite).
In supergene ores, only low recovery rates (ca. 40%) are achieved due to the polymodal and complex platinum-group element distribution. To achieve higher recovery rates for the platinum-group elements, hydrometallurgical or pyrometallurgical processing of the bulk ore would be required, which is not economically viable with existing technology. KW - Bushveld Complex KW - Merensky Reef KW - PGE KW - PGM KW - supergene ores KW - weathering Y1 - 2021 U6 - https://doi.org/10.3749/canmin.2100023 SN - 1499-1276 VL - 59 IS - 6 SP - 1381 EP - 1396 PB - Mineralogical Association of Canada CY - Ottawa ER - TY - JOUR A1 - Elsässer, Joshua Philipp A1 - Hickmann, Thomas A1 - Jinnah, Sikina A1 - Oberthur, Sebastian A1 - Van de Graaf, Thijs T1 - Institutional interplay in global environmental governance BT - lessons learned and future research JF - International environmental agreements: politics, law and economics N2 - Over the past decades, the growing proliferation of international institutions governing the global environment has impelled institutional interplay as a result of functional and normative overlap across multiple regimes. This article synthesizes primary contributions made in research on institutional interplay over the past twenty years, with particular focus on publications with International Environmental Agreements: Politics, Law and Economics. Broadening our understanding about the different types, dimensions, pathways, and effects of institutional interplay, scholars have produced key insights into the ways and means by which international institutions cooperate, manage discord, engage in problem solving, and capture synergies across levels and scales. As global environmental governance has become increasingly fragmented and complex, we recognize that recent studies have highlighted the growing interactions between transnationally operating institutions in the wake of polycentric governance and hybrid institutional complexes. However, our findings reveal that there is insufficient empirical and conceptual research to fully understand the relationship, causes, and consequences of interplay between intergovernmental and transnational institutions. Reflecting on the challenges of addressing regulatory gaps and mitigating the crisis of multilateralism, we expound the present research frontier for further advancing research on institutional interplay and provide recommendations to support policy-making. KW - institutional interplay KW - transnational institutional interplay KW - global KW - environmental governance KW - transnational governance KW - multilateral KW - environmental agreements Y1 - 2022 U6 - https://doi.org/10.1007/s10784-022-09569-4 SN - 1567-9764 SN - 1573-1553 VL - 22 IS - 2 SP - 373 EP - 391 PB - Springer CY - Dordrecht ER -