COPPER(II) EXTRACTION FROM AMMONIA LEACH SOLUTION

Hydrometallurgical processing of copper-bearing materials (ores, concentrates, by-products) is usually done with the use of acidic or ammonia leaching. In the case where a leaching feed material contains significant amounts of carbonate rocks and iron minerals the second method is preferential due to a higher process selectivity. However, it can also be problematic considering possible ammonia transfer during the subsequent extraction process. The paper presents results of extraction of copper(II) from ammonia leach solutions. The effect of a type of extractant, its concentration and type of diluent in organic phase on extraction efficiency and ammonia transfer was studied. A few commercial extractants were examined, namely LIX 84-I, LIX 984N, LIX 54-100. The results clearly indicate that in the case of extraction systems using hydroxyoximes the extraction efficiency is remarkably higher than for beta-diketone reagent. Presented studies proved that extraction efficiency of Cu(II) is also dependent on the type of diluent and is less favourable for systems with non-aliphatic diluents. It was observed that ammonia co-extraction occurs and depends on examined parameters. Scrubbing of loaded organic phase showed that ammonia can be removed almost completely using double wash with sulfuric acid solution.