<p>Shell GTL Fluid G80 is a new generation, synthetic, aliphatic diluent supplied by Shell for copper solvent extraction (SX) operations. G80 is produced from natural gas via a gas-to-liquids (GTL) process, resulting in a hydrocarbon composition that differs from that of mineral-oil-derived diluents: it is composed exclusively of linear paraffins and lightly (methyl, ethyl) branched iso-paraffins in the C₉–C₁₆ range, with a very small amount of naphthenes and aromatics. Due to its unique chemical composition, G80 has a low vapor pressure, a high flashpoint (84&#xa0;°C) in combination with a low viscosity. It has a low level of toxicity, is readily biodegradable, and is virtually odorless. The performance of G80 as a diluent was investigated for extraction of copper from two sulfate feed solutions (containing 6 g/L Cu and 18 g/L Cu, respectively) with the commercial extractants LIX® 984N, ACORGA® OPT5540 and ACORGA® M5640. Good phase disengagement, high copper loading and fast extraction/stripping kinetics were observed in laboratory tests carried out under common operating SX conditions. The copper/iron selectivity remained excellent. The effects of high extractant concentration, commonly used for the recovery from oxidic copper deposits in Sub-Saharan Africa, were also studied. Specifically, the impact of a 35 vol% extractant concentration on the solvent’s viscosity was evaluated. Despite G80’s low aromatic content (&lt; 400 ppm), the range of viscosities measured by standard methods is acceptable for most copper SX operations. In addition, lab tests showed that the evaporation rate was lower than that of common aromatic and dearomatized diluents, so that less top-up will be required. The performance characteristics of G80 were compared with those of two mineral-oil-derived diluents: an aliphatic diluent and a mixed aliphatic–aromatic one.</p> Graphical Abstract <p></p>