Resource recovery and remediation of alkaline wastes

Project Description

This project addresses environmental problems and potential benefits posed by alkaline waste materials. These are generated in large quantities by many industrial processes around the world. The project will provide fundamental scientific understanding that will deliver environmental improvements in two ways. Firstly through understanding how metals contained in alkaline wastes are mobilised through biological processes, thus posing a potential risk to the local environment. Secondly, the same scientific understanding may be used to extract and recover e-tech metals contained in the waste material, and then leave it in a more stable state.

Large amounts of alkaline (i.e. bleach-like) wastes are produced by industry around the world. Mostly, these are landfilled, and can pose environmental risks. Water percolating through the landfill may form "leachate" toxic to aquatic life; dust generated from landfill activity can pose public health hazards. But the wastes can provide resources we would like to recover, this is particularly the case for metals important to green technologies, such as vanadium for high grade steel manufacture in offshore wind turbines, lithium and cobalt for vehicle fuels cells and rare earth elements crucial for next-generation photovoltaics. Alkaline waste has enormous potential for metal recovery; from the large amounts produced, and from "legacy" stockpiles going back 100 years. Unfortunately, the concentration of metals within the leachate is low: recovering metals from it would be expensive while directly digging up legacy sites would cause environmental disturbance.

The solution is found in recent ground breaking research done by the project team. Tests showed that the natural weathering process may be accelerated by a covering of a compost layer. Metals, like vanadium, were concentrated into the leachate so that they may be extracted with no physical disturbance. Compost used was derived from "solid municipal waste", removing this from landfill, the layer of compost also reducing dust generation from site. The compost also allows more CO2 to penetrate the waste where it reacts to form carbonate minerals, a means of carbon sequestration. The specific mechanism by which metals are remove from the waste by microbial communities is not fully understood and is therefore the target of the main scientific research effort. The work will also adapt existing technology for recovery of the metals from the leachate, thus avoiding environmental pollution. This research will take place in partnership with the Environment Agency and industrial stakeholders to ensure the process gets the necessary regulatory scrutiny to support the full-scale deployment of this environmental technology.

In addition to the scientific challenges, there remain considerable economic, legislative, environmental and social issues that need to be addressed to ensure the responsible development of these methods. R3AW will tackle these challenges by bringing together key commercial partners with a multi-disciplinary team of environmental scientists, waste policy experts and internationally-leading specialists in systems analysis and stakeholder engagement to pave the way to transform resource recovery and environmental remediation in the steel, cement and other industries.