Alpha Torbanite Project, Queensland
The Alpha Torbanite project is located approximately 50km south of the Central Queensland town of Alpha. The Alpha Torbanite deposit consists of two seams – an upper seam of cannel coal with an average thickness of 1.12m and a lower seam of cannel coal containing a lens of torbanite with a thickness of up to 1.9m.
The project has been subject to extensive exploration and laboratory testing since its initial discovery in 1939, over 80 years ago. During 2019 SRK Consulting (Australia) Pty Ltd (SRK) was engaged to reassess the project strategy. This resulted in a report by SRK setting out a potential new development strategy, which is based on the production of a diversified suite of value-added products.
SRK noted that, in contrast with typical oil shale deposits, the Alpha Torbanite is exceptionally high-grade, containing up to 650 litres of hydrocarbons per tonne of torbanite, and is capable of producing high-value bitumen, light crude oil and activated carbon. Additionally, the torbanite has the ability to deliver high-quality value-added products through appropriate investment in processing infrastructure.
SRK has recommended a staged work program which will initially focus on the extraction and analysis of torbanite and cannel coal bulk samples from trenches or costeans from one location in order to fully characterise the deposit, as well as undertaking a comprehensive retort testing program across a range of conditions to assess optimal outputs.
The maiden Mineral Resource Estimate for the Alpha Torbanite Deposit was released 9 March 2022 (Maiden JORC Resource for Alpha Project)
Local Geology of the Alpha Deposit
The Alpha Torbanite deposit consists of two seams namely an Upper and Lower seam which sit at the base of the Colinlea Sandstone. The Lower seam is equivalent to the ‘E’ seam within the Colinlea Sandstone within the Galilee Basin. Seam structure of the deposit is simple with the two seams – the Upper and Lower seam – with an average interburden of 16 m. The interval between the two seams is dominantly quartzose to lithic sandstone with minor conglomerate, siltstone and claystone (Figure 1). The Upper Seam is classified as a cannel coal and has an average thickness of ~1 m and the Lower Seam has an average thickness of ~2 m. The lower seam is the main oil-yielding unit of the deposit. It consists of two main types of oil shale namely cannel coal and torbanite, which is olive-grey to olive-black and is finely laminated. The torbanite is lenticular in shape and has a variable thickness. The Lower Seam can generally be split into three plies, as described below:
- L1 – comprising a relatively clean cannel coal interval
- LT – comprising the main torbanite interval, including coal bands
- L2 – comprising a relatively clean cannel coal interval.