An experimental study of the interaction of malachite, atacamite and chrysocolla with a reactive gangue during sulphuric acid leaching

摘要

The chemical interactions between some copper minerals and a potentially reactive gangue during a sulphuric acid column leaching have been studied on a laboratory scale. To ensure that the feed material had the desired composition, an artificial rock aggregate was prepared, containing 57% short-term acid inert quartz, 42% reactive gangue (4 smectites, 2 kaolins, 1 illite, 1 zeolite) and 1% copper mineral phase (atacamite, chrysocolla, malachite). Overall, the copper recovery in the leachate depends on the gangue composition, although the absolute values depend on the type of mineral phase (carbonate, chloride, silicate). A cavity formation in the middle of the column was a typical feature of all the smectites in their maximum expanded state. The de-lamination of kaolin sheets and the consequent physical barrier formation create an initial acid accumulation at the column top. Partial dissolution of smectites and illites was observed. The presence of major elements in the leachates reflects the cation availability in the free exchange positions or easy dissolved aluminium-silicate framework sites. Cu-cation exchange capacities increase in residues due to the Cu-entry in the exchange positions and the presence of residual Cu.