Authors: Lisa O’Donoghue, Chinnam Rama Krishna, Eva Ujaczki and John Mulcahy
Summary: Ireland is home to primary industries in mining, materials processing and power generation. Today, most waste outputs associated with these industries are either sent for disposal or exported. The research focused on techniques for mechanical and physical separation, to unlock valuable materials such as iron, aluminium, calcium and critical raw materials (gallium, indium and phosphorus).
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Ireland is home to primary industries in mining, materials processing and power generation. Today, the majority of waste outputs associated with these industries are either sent for disposal or exported. There is, however, potential to assess these wastes as secondary raw materials, recover any valuable metals and find alternative applications for the end waste that can contribute to a circular economy. In the light of this, the high-level objectives of the Raw Materials Ireland Project are defined as follows:
The specific objectives to achieve these are to:
A detailed waste inventory and characterisation study of 24 waste samples from 12 different industrial sites across Ireland was undertaken as follows:
The results of the analysis revealed commonalities among a group of valuable materials and CRMs that were present in the majority of the wastes as follows:
The development of an initial waste inventory with detailed composition of national wastes is key to informing Irish policymakers of the secondary raw materials resources available and the potential contributions they can make to circular economy.
The recovery strategy developed focused on separating the wastes into the following concentrated fractions:
The research focused on techniques for mechanical and physical separation, such as ball milling and filtration, magnetic separation, dissolution studies and gravity separation processes, including the Mozley superpanner and the multi-gravity separator (MGS). The test results showed that the gravity separation techniques gave the best results where individual wastes demonstrated enhanced responses for either the Mozley superpanner or the MGS, based on their specific characteristics.
Process flows based on the results were developed for specific market applications for the wastes, including cement clinker replacement, cement filler, aggregates and geopolymer applications.
The process flows illustrate processing steps to unlock the valuable materials including base metals and the calcium rich-fractions. In addition, a process flow for multiple wastes was developed to showcase a circular economy approach where the scaling of the process and the capability to co-process different wastes augment the economic viability of the operation.https://www.epa.ie/media/epa-2020/research/epa-funded-research/Report-cover-388.jpg