RECOVERY OF RARE EARTHS FROM ELECTRONIC WASTE

Abstract

There is a growing worry about electronic waste (e-waste), which is currently the world's fastest-growing waste category. This thesis is an extended literature review of current rare earth element (REE) recovery practices, and plasma technology has been investigated as a potential contender (It's worth noting that this investigation aligns with our capabilities at Cranfield, where we have a plasma facility for such research). To address this issue, a new electrochemical recovery (ER) method has been created as a potential replacement for the current methods that rely on pyrometallurgy and hydrometallurgy. This new process aims to recover valuable base metals, precious metals, and rare earth elements (REEs) from e-waste. Rare earth elements (REEs) stand as indispensable constituents within a myriad of cutting-edge technological marvels that span the global landscape of modern appliances. As a result, analysis of recycling rare metals from electronic waste was conducted by reviewing peer-reviewed literature and calculating economic factors for 17 elements. The chosen recycling method is the plasma arc furnace, which employs a high-temperature plasma arc (2000-10,000 C) at a relatively high pressure of 400-1000 millibars absolute under an inert environment, such as Helium and Argon, to smelt the metals. The total heat required to melt each metal from room temperature was calculated using specific heat and heat of fusion, allowing us to determine the power rating needed for the plasma furnace to smelt each rare metal. Also, the payback period was calculated based on approximate furnace prices and their mass handling capacities. The metal with the shortest payback period is considered viable for the recycling process. The selected masses for analysis were 1 kg, 3 kg, 10 kg, 50 kg, 200 kg, and 5 tons. The 5-ton Super plasma-arc furnace from FOB Helsinki is capable of recycling scrap for only 30 EUR/ton while recovering all metals with minimal energy requirements. This study provides an extended literature review of recent studies focused on the retrieval of rare earth elements from electronic waste, with a particular emphasis on utilising plasma for the recovery process.