Proof of concept for a new process to recover metals from furnace slag & dross with a 90% energy saving

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Slag is a by-product of metal smelting, and several 100,000 tonnes of it are produced everyyear in the process of refining metals and making alloys. Slag usually takes the form of aloose aggregate with lumps of varying size. Slag contains impurities from the metals, whichfloat to the top during the smelting process. Also, slag forms a protective crust of non-metallic& metallic oxides on the surface, protecting the liquid metal underneath from oxidation.When smelting is complete, the slag is skimmed off and deposited in a slag heap to ‘age’.Slag actually has many uses, and rarely goes to waste, but it is used in low value applicationssuch as ballast in concrete and in aggregate road materials. However, slag retains significantamounts of metals, and these are sometimes recovered by re-melting the slag, but this isextremely expensive with a very high energy burden.Our idea is to use a novel technology to selectively break down the non-metallic componentsof slag from the metallic particles. This novel technology was originally developed to recyclewaste glass and is relatively new, and has not been applied commercially to other materials.We have carried out some simple tests and the results indicate there is some degree ofpreferential reduction and separation of metal from non-metal particles.Further research will allow us to explore the novel process more closely, and we believe thatwith modifications the technology could be refined to treat a variety of different NFM slagmaterials very effectively and should significantly improve metal recovery from all slag. Themetal recovery route will vary from material to material but almost any metal recovery fromslag could be achieved using our concept process route.The benefits of the proposed process vs existing process are:• 90% saving in energy cost• Rapid local turnaround of material• 90% cut in the carbon footprint• Retain control of metal recovered.• Enable smelters to recover more metal