CENSZ · Critical Elements in Nonsulphide Zinc Deposits

CENSZ – Critical Elements in Nonsulphide Zinc Deposits

The definition “Critical Elements” (CE) was assigned by the “European Union AdHoc Working Group” to those raw materials that are characterized by high supply risk and their high economic importance for EU economy. The metals Gallium, Indium and Germanium (GIG) occur in a number of different natural deposits from which they are currently recovered as secondary metals. There is currently no collective database defining the distribution of these elements systematically and thus the supply of the metals is linked to the individual mine from which they are currently recovered. The central aim of this project ‘CENSZ’ is to provide a comprehensive database of GIG deportment within Nonsulphide Zinc+Lead (NSZ) deposits, that form as a result of geological processes in the Critical Zone of the Earth’s crust (The Earth’s surface crustal environment). Sulphide deposits that are progenitors of supergene NSZ mineralisation contain sphalerite which is a known host for the GIG elements. The factors determining the geochemical distribution of GIG within weathering profiles are still only poorly understood. Gaining an understanding of the mechanisms governing mineralogical residence is fundamental to unlocking potential new processing streams. The importance of metals in society is increasingly recognised within the EU as reported in 'The Raw Materials Initiative - Meeting Our Critical Needs for Growth and Jobs in Europe', The European Technology Platform on Sustainable Mineral Resources and the European Innovation Partnership on Raw Materials. As the EU is highly dependent on imports of CEs, new strategies are now needed to enhance resource efficiency, recycling and reuse. The security of supply of CE is particularly acute, due to the lack of substitutes and because the resource presently residing in the anthroposphere is far too small to meet current demand through recycling alone, let alone address the increasing future demands. The EU recognises the need for research projects and training which promote innovative approaches to exploration, extraction and beneficiation and which enhances the knowledge base of mineral deposits both within the EU and further afield. The underpinning aim of such actions is to achieve greater efficiency in the utilization of the primary resource base which, if not addressed, will lead to a diminished effectiveness of the European mining industry and the high technology manufacturing ability of the EU. The elements GIG have all been highlighted in studies concerning security of supply of key commodities for European High Tech industries. Gallium is used in thin layer photovoltaics, intergrated circuits and white-light LEDs. Indium is used in displays and thin-layer photovoltaics, whilst germanium is used in fibre-optic cables and IR technologies. Many of such concerns are the result of their recovery as by-products from other processes. As such they lack their own production infrastructure, making both their current and future supply vulnerable to the changing fortunes of extraction operations for another commodity that effectively determines the potential viability of CE recovery. Complicating the supply position further is the fact that these metals are in part recovered from geographically restricted regions, making their supply vulnerable to changing political and economic factors. This project aimed to perform detailed mineralogical and geochemical studies of examples of known deposits, many within Europe. The key questions of this study were: 1) What is the fate of GIG from progenitor sulphides during the formation of NSZ deposits? 2) What is the behaviour of GIG under different geochemical conditions in the critical zone? 3) What are the climatic conditions most favourable for NSZ deposit formation? 4) Which of these deposits might be more amenable to low impact processing options?

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз