When Samin Ltd decided in 1969 to re-open the Burra mine for open pit extraction and onsite processing of the substantial remnant orebody of oxidised copper minerals, it was initially envisaged that the copper recovery method would involve an acid leach and cementation process, with the sale of the product copper cement to a smelter. This route was soon rejected due to the presence of a high proportion of acid-consuming host rocks. The Australian Mineral Development Laboratories (AMDEL) were commissioned to develop a treatment route, under the guidance of their Director, Mr N. Draper. Mr Draper joined Samin in 1970 as Chief Metallurgist and Director, and following the takeover became Chief Metallurgist and Associate Director of Poseidon. The options of acid leaching and flotation of the ore were soon rejected due to high acid requirements and low copper recoveries, respectively. The ammonia leaching route was selected for development and the process that subsequently evolved (Stage 1) was developed from reports on the Kennecott Copper Corporation's operation at Kennecott in Alaska in the early 1900s, and on the Nicaro nickel operation in Cuba. The Stage 1 process operated from early 1971 to October 1973, when it was shut down for the commissioning of the whole-of-ore treatment process (Stage 2). The author saw the last 3 months of the Stage 1 operation, and his description is based on observations made at the time, on verbal discussions with the initial operating crew, and on reports of the operations. The plant was constructed and commissioned under the guidance of the Manager of Operations, Mr H.J. Rich, and the Maintenance Engineer Mr N. van Buuren. In essence, the Stage 1 operation developed and designed by AMDEL was a direct ammoniacal percolation vat leach process of a deslimed crushed ore, developed from operational reports for the Kennecott operation in Alaska. The Stage 1 plant flow sheet is shown in the Appendix. The technology was developmental, with no similar process in operation in the world, and understandably numerous problems were encountered. This report discusses and describes the operation and the problems encountered, along with variations from the original design. The Burra ore minerals were principally malachite (CuCO3. Cu(OH)2), azurite (2CuCO3.Cu(OH)2), and chrysocolla (CuSiO3.2H2O), with a cuprite (Cu2O) proportion increasing at depth. Laboratory leaching tests defined that these minerals, excepting chrysocolla, were highly soluble in ammoniacal liquors. Chrysocolla was insoluble along with all the remaining gangue materials. It was therefore essential that Stage 1 ore mining avoided the high chrysocolla areas in the mine. Alternative processes were being investigated at the time for the future treatment of chrysocolla and of fine ores trapped in montmorrillonite clay-hosted gangue, as it was realised that the presence of clay would inhibit solid/liquid separation of leached slurries. Laboratory and pilot plant research into a process to treat the whole of the run-of-mine ore continued for two years in parallel with the Stage 1 operation. The flotation option was revisited, along with reduction roasting of the ore. Encouraging reduction roasting results had been show in laboratory tests, which were confirmed with pilot testwork in Europe and America at the engineering company laboratories of Lurgi and Envirotech, respectively. Natural gas would be available in the area at the time of a roaster installation, and there was great interest in the cleaner fuel. Again, the technology was ultimately successfully developed without reference to any similar operation in the world (except perhaps the Nicaro ammonia leaching nickel plant in Cuba, access to which was not available at the time). This report particularly discusses and describes the Burra Stage 2 operation and the numerous problems encountered. Stage 2 commenced its commissioning phase in October, 1973, after a 14 day plant closure to cut-in new equipment above that used in Stage 1. The commissioning phase extended for almost 3 years before achieving economic viability. Stage 2 ore roasting ceased due to exhaustion of ore reserves on February 25, 1983. A 1976 flowsheet and equipment description is also presented in the Appendix.