METS reviewed extensive reports detailing design and operability choices made during the historical operation of the Bottle Creek Gold Project, which ultimately led to the closure of the plant. Extensive identification and evaluation of the past mistakes and advances in gold processing technology and mineralogical assessment since the 1980s improve confidence in ensuring that the same mistakes would not be repeated. A number of opportunities were identified for improvement on the historical project. Significant improvements in mineral characterisation techniques now provide more comprehensive insight into the factors that shape process selection and design, including mineral identification, gold association and grain size. In the past, technological limitations restricted the quality of information obtainable during both project development and project operation; such limitations contributed to the issues experienced within the Bottle Creek project. There were issues with the comminution section of the plant, mostly arising from high variability within the deposit. Semi-Autogenous (SAG) milling would likely eliminate these issues, which was initially trialled at Bottle Creek, however proved ineffective due to the soft nature of the oxide ore processed at the beginning of the project. Since the 1980s, huge advances in SAG milling equipment design and operation have been made. The high silver content of the ore was one of the largest oversights for the project. High silver loading on the carbon significantly decreased the economic viability of the project due to increased stripping costs following the conventional carbon-in-pulp (CIP) circuits. Seeking a process flowsheet that is tolerant to high silver levels, such as the Merrill-Crowe process, would have been a more viable option. This paper summarises new testwork and project developments, including the establishment of a commercial flowsheet.
CITATION:Connelly, D, 2019. The Bottle Creek gold project revisited, in Proceedings World Gold 2019, pp 683688 (The Australasian Institute of Mining and Metallurgy: Melbourne).