Mineralogy
The mineralogy of the Wetar orebodies consists primarily of primary and secondary copper sulphides hosted in massive pyrite (70% - 85%). The predominant secondary copper mineral is covellite at Kali Kuning. The Lerokis orebody contains mainly covellite and chalcopyrite.
Wetar Demonstration Plant Review
A 100,000 t bulk sample was crushed and stacked into 4 bunded heaps, with variable heights, to allow for testing of different leaching variables in each heap to assess optimum parameters such as crush size, aeration and irrigation rates.
Heap 3 had the best results with a total recovery of 80.3 % Cu after 645 days leaching.
The average of incremental acid generated for typical heaps was 1.2 kg acid/kg Cu Leached, thus process solutions require neutralisation in commercial operations.
Irrigation and aeration application rates proved to be effective controls on temperature. Heaps operating at an average sustained ore temperature of 75-85°C.
The Solvent Extraction and Electrowinning plants achieved nameplate capacity. 99.7% of the cathode produced by the demonstration was sold as LME 'Grade A' product.
Model leach recovery kinetics based on the commercial scale heap heights during the demonstration phase have been used to generate production leach curves in the BFS.
