*SC5-11-2014/2015: New solutions for sustainable production of raw materials e [2015] New metallurgical systems* Novel Environmentally-friendly Ore Processing Techniques for the 21st Century Gawen RT Jenkin & Daniel J Smitha Andrew Abbottb aDepartment of Geology, University of Leicester, UK, [email protected] bDepartment of Chemistry, University of Leicester, UK Conventional ore processing Ore + Energy (€) Metal + CO2 (☹) + Wastes (€ ☹, CO2 ☹) Can we do better? – Need a low energy (€) process, more environmentally compatible A new chemistry - ionic liquids • Anhydrous salts that are liquid at low temperature – Powerful solvents • • • • High selectivity in dissolution and recovery Amenable to electrochemistry Successfully used to recover metals from scrap and oxides No large volume/low concentration aqueous waste CuCl2 dissolved in different ILs BUT, must be: • Low cost • Environmentally compatible • No registration requirements - We use non-toxic biodegradable Deep Eutectic Solvents Gold dissolution by oxidation with I2 Reflected light galena BEFORE AFTER pyrite el 7 µm quartz 7 µm el = electrum (Ag:Au ~50:50 wt%) Sample: gold ore, Cononish deposit, Scotland Solution: I2 in ionic liquid, 10 mins, ~50°C Abbott et al. 2014, Electrocatalytic Recovery of Elements from Complex Mixtures using Deep Eutectic Solvents, Green Chemistry, doi 10.1039/C4GC02246G Gold dissolution and recovery Gold panned concentrate Electrodeposition from solution ~20 hours Dissolution by oxidation in ionic liquid with I2, 48 hours Abbott et al. 2014, Electrocatalytic Recovery of Elements from Complex Mixtures using Deep Eutectic Solvents, Green Chemistry, doi 10.1039/C4GC02246G Dissolution by electrolytic reduction • Change in solution colour indicates dissolution of other minerals: Ionic liquid Pyrite in ionic liquid Arsenopyrite… Pyrrhotite… Chalcopyrite… Covellite… Loellingite… Bornite… Chalcocite… Summary • We have not yet found a native metal/metalloid, sulfide, sulfosalt or telluride (e.g. calaverite AuTe2) that we cannot dissolve in DES ionic liquid. • Electrolytic recovery of Au from solution is proven (+22 other metals) – could quantitatively separate metals by different voltages. • Ionometallurgy could thus offer a whole new set of environmentally benign tools for metallurgists. • Looking for partners: – High grade complex deposits and concentrates optimum – Lower grade deposits, heap leach on the horizon Cononish electrum inclusions in pyrite (Hill et al. 2013) • Contact us: [email protected], see Gawen Jenkin, Dan Smith