ASPIRE - Accelerated Supergene Processes in Repository Engineering

点击翻译按钮获取中文摘要

The UK faces serious strategic challenges with the future supply of aggregates, critical minerals and elements. At the same time, the UK must sustainably manage multimillion tonne annual arisings of industrial, mining and mineral wastes (IMMWs). The amount of these wastes generated is projected to increase over the coming years, particularly (i) ash from the combustion of biomass and municipal solid waste, and (ii) contaminated dredgings. These wastes will continue to be landfilled despite often containing valuable resources such as high concentrations of critical metals, soil macronutrients and useful mineral components, some of which actively drawdown atmospheric CO2. The fundamental aim of the ASPIRE (Accelerated Supergene Processes In Repository Engineering) research project is to develop a sustainable method by which ashes, contaminated dredgings and other IMMWs can be stripped of any valuable elements. These stripped elements would then be concentrated in an ore zone for later retrieval and the cleaned residues also returned to use, for example as aggregates, cement additives, or agricultural amendments (including those for carbon sequestration through enhanced mineral weathering). It is a very challenging problem to devise a truly sustainable method to achieve this is an economically viable way, and almost all processes suggested so far in the literature for leaching wastes are themselves carbon and chemical intensive and thus non-sustainable.We are proposing research that comprises the first steps in developing the "ASPIRE waste repository" concept with accelerated analogues of ore-forming "supergene" processes engineered in, such that the dormant waste undergoes processes to (i) concentrate valuable components (e.g. critical metals, phosphate) as an anthropogenic ore to facilitate their future recovery, and (ii) concurrently decontaminate residual mineral material so as to make it available as a bank of material to drawdown for "soft" uses in agriculture, silviculture, greenspace, landscaping in new developments, habitat creation and/or as a cement/concrete additive or replacement aggregate.The processes investigated rely on rainwater passing through a vegetated surface layer which releases naturally occurring compounds from the plant roots and/or other natural organic matter which then pass through and strip valuable elements from the IMMW. The mobilised elements will then pass into a capture zone where they will be stripped from solution and concentrated to form an artificial ore. The research project will seek to engineer the internal processes of the temporary storage waste repository to optimise this. At the same time the upper vegetated surface of the waste repository will serve as greenspace with commensurate ecological and amenity value for local populations.Among the key research challenges is in how to engineer the internal ASPIRE waste repository processes which rely on complex biogeochemical interactions and flow behaviour. Another critical research challenge is to develop an understanding of stakeholder and wider acceptability of this concept which does not fit with current legislation on waste management. With this project we seek to provide a circular technology solution for how we can sustainably manage the future multimillion tonne arisings of IMMW at a critical time as the UK government develops strategies and supporting regulation for the transition to a circular economy.