In the BIOMOre project, sustainable development indicators were used to compare the social, environmental and economic impacts of the BIOMOre technology with conventional mining. An environmental impact assessment was performed for a generic site, the current European legislation was reviewed. Solutions for site rehabilitation were also developed alongside the technology.
Transparency and communication are central to obtaining social acceptance of the BIOMOre technology. The social acceptability of the BIOMOre technology was studied through discussions and exchanges with a cross-section of stakeholders. BIOMOre has developed an informative website. Brochures have also been produced and distributed. News and social networking services were used. BIOMOre has a YouTube channel, a Twitter account and a group on LinkedIn. An image film, accessible on YouTube, was produced.
The economic viability of the BIOMOre process was assessed in light of the actual metal production costs and market prices using the experimental test results.
The core of the BIOMOre project was the development of the BIOMOre process at lab-scale and the subsequent underground testing of the process at a test ore block. The tests were carried out in a Kupferschiefer ore at the KGHM Rudna copper mine in Poland, selected on the basis of geological, hydrogeological and legal issues. A wide range of theoretical investigations and models were developed for supporting and predicting purposes. This modelling toolbox addresses the fracturing technology and bioleaching process as well as geological, hydrogeological and economic issues.
The characteristics of the ore present at the underground site determined a four stages operation:
- Water-washing step to remove halite;
- Acid leaching to dissolve carbonates, which also leaches some copper from acid-labile sulphide minerals;
- Ferric iron leaching to oxidise sulphide minerals quantitatively and solubilise most of the copper present in the ore;
- Neutralization step to increase pH to neutral conditions and to eliminate residual bacterial activity.
At the end, BIOMOre achieved, among many other things, the following:
- ISR (in-situ recovery) feasibility criteria were systematized and generalized to predict production rates for given deposit characteristics and leach performance
- CAPEX/OPEX estimates have been made possible
- A full-scale ISR project NPV (net present value) model was established for various ISR options
- The applicability to European ore deposits was systematically assessed. The deposit data were mostly not sufficient, in particular, to assess ISR mining option.
- The effect of fracturing for ISR applications is constrained by the incompressibility of rock.
- The possible effects of ex-situ bio-oxidation and in-situ bio-leaching were quantified and assessed economically.
- Technological feasibility/environmental compliance and economic viability of the BIOMOre process (ISR) and the applicability criteria were quantified.
- The Zechstein formation including Cu dolomite/shale/sandstone in the Rudna mining zone is not applicable to the BIOMOre process. The test results and simulated production scenarios demonstrate uneconomic ISR performance.
- Every deposit needs to be assessed individually to confirm ISR amenability and viability, in particular to apply the BIOMOre process.
- A comprehensive economic model (NPV) has been developed and applied to several ISR performance scenarios including vertical wellfields and horizontal wells.
- The comprehensive evaluation of known European deposits with regard to the applicability of the BIOMOre process has demonstrated that none of the deposits fulfill the criteria entirely. In many cases, available exploration data and test results are insufficient for final conclusions.
- Several potential application scenarios were identified:
The innovative technology being explored within the BIOMOre project has the potential to be implemented as an alternative and much more environmentally-friendly approach for metal mining in future decades. Deep in situ bioleaching could reduce costs of extracting and recovering metals, increase the amount of ore that is accessible, and lower the environmental impact of mining activities by avoiding the building of large (underground) infrastructure and avoiding the production and long-term management of large quantities of waste materials. This paradigm shift in how we obtain essential metal commodities in the future will require social acceptance both in Europe and elsewhere in the world. Key for success will be to find deposits that meet the various criteria for the BIOMOre process to be economically viable.
