In-situ recovery (ISR) is accepted and applied across many geographies, and approximately 50% of the world’s uranium is currently extracted by using an ISR method (World Nuclear Association, 2014). The low environmental impact, the elimination of risk for mine workers and the fact that all of the lowest-cost producers of uranium use an ISR approach should raise interest from traditional miners (IAEA, 2014). However, the broader application of ISR to other commodities and mineral systems remains limited. A number of demonstration (experimental) copper projects have been undertaken (Sinclair and Thompson, 2015) with a few copper projects in Arizona being close to demonstration (Florence, 2018 and Gunnison, 2018). Evidence of very few economically operating ISR copper projects can be found (for example, the Russian, Uralgidromed OAO, built by the Russian Copper Company in 2005 and operated as an ISR facility from the Gumeshevskoye deposit (Russia Mining, 2018). A number of gold deposits, particularly paleochannel deposits, have also been considered for ISR, but, to the best of our knowledge, only limited demonstration and no commercial operations have been established, yet (Kuhar et al, 2018 and references therein).
While the broader uptake of an ISR approach in new or greenfield projects may be emerging (Kuhar et al. 2016), we would contend that the application of an ISR approach (or ISR enabling technologies) to brownfield sites has massive potential (in a shorter time-frame) for increasing total values recovery from operating mines; extending mine-life, production and jobs; and for positive economic impact in rural Australia.
Over recent years, the combination of cost (profit margin) pressure and major advances in a number of relevant technologies has made researchers, companies and regulators realise the potential benefit for the broader use of ISR and the potential for broader application of ISR-enabling technologies (Batterham and Robinson, 2018). In some instances this has involved a consideration of the application of ISR-enabling technologies into remediation and the revisiting of old heaps/dumps for additional value recovery.
Potential additional targets include stranded, small and otherwise uneconomical ores that remain when mines are closed/abandoned and miners move to more attractive targets. These targets would include residual values in the floors and walls of pits or underground operations, material in rims of or between pits, otherwise inaccessible mineralisation (e.g., below established infrastructure) and less attractive (e.g., low-grade) mineralisation that does not justify conventional (open-pit or underground) workings.
While we work with companies to identify and progress a number of immediate opportunities, we are working in parallel programs on the critical enabling technologies. In particular, ISR opportunities are being sought where improved mining outcomes (economic, societal, environmental and health and safety) can be achieved while allowing developing technologies to be demonstrated and tested in “the real world” and further optimised. Within an “In-Place Mining” strategic research focus (Mining3, 2018) involving “In-Line”, “In-Mine” and “In-Situ” Recovery, Mining3 are leading a coordinated and collaborative thrust to progress this portfolio of projects and research directions in Australia. Specific challenges that have been identified with industry are being targeted, these include:
- Improving ore body characterisation with a focus on in-situ target mineral porosity/permeability liberation, and access.
- Increasing and sustaining in-situ access for lixiviants through target ore bodies.
- Understanding and modelling new and conventional fracturing technologies and outcomes.
- Design of more selective and active lixiviant systems and improving lixiviant–mineral (value and gangue) interactions (i.e., improved understanding of in-situ chemistry).
- Development of improved containment strategies including commercially available and novel barrier technology.
- Development of well field optimisation strategies based on individual well hole production and flow models.
- Improving awareness of ISR and communication strategies to facilitate social licence to operate.
- Developing and testing robust, stand-alone sensors for real-time downhole environmental and production monitoring and optimisation.
The opportunity has been recognised by many in our industry and in parallel with the above research and technology development effort, real ISR projects are being progressed within many companies that will take up these technologies and “real-world” test them almost as soon as they are ready. While the focus of these projects appears to be largely copper, gold or copper and gold, they still range from abandoned/historical mines, to near end-of-life mines and new prospects altogether. We remain convinced, however, that the number and range of opportunities is far greater than generally realised, and an early demonstration of full ISR extraction or application of enabling technologies to extend mine life (for example) will see a further increase in the level of interest mining companies pay to these developments.