Currently, there is no comprehensive research data in Finland on the reuse potential of old mining waste areas. In the REPower-CEST project, we are doing a national study on the utilization potential of old mining waste areas (tailings and waste rock) in Finland. This is part of the Critical Raw Materials Act (CRMA) and member state reporting.
The research results will contribute to the sustainable utilization of raw materials from secondary sources and reduce the investment threshold for private operators. The investigation gives a preliminary assessment of the concentrations of useful minerals and metals and for instance the processability of the waste in couple selected tailings sites. Preliminary environmental studies and socio-economic usability assessment will be carried out within the project.
The results are compiled into the Mineral Deposit Database (MDaE) managed by GTK and reported as part of the national critical raw materials reporting on mining waste guidelines (CRMA Article 27). The resource classification is done according to the United Nations Framework Classification for Resources (UNFC), which is a European-level classification method by decision of the European Commission. In addition, the development of the data model, user interface and data distribution of the extractive waste extension of the mineral deposits database will be carried out in accordance with CRMA, so that the raw material potential of the extractive waste areas can be properly reported.
Research data obtained from mining waste areas can be used to examine environmental impacts
The technical archive data of the old mines will be reviewed, and the results obtained in previous research projects (e.g., Kajak projects) adopted. Approximately 15 extractive waste areas are selected as the target areas for the preliminary field investigation of raw material potential ("baseline study") to verify the concentrations of useful minerals and metals.
With the baseline study, we get an idea of the exploitation potential of the mining waste areas and the need for further research. The research includes, e.g., the following methods: geochemistry, grain size determination, mineralogy, elevation model, volume modelling, density, and solubility tests. For one or two most potential sites, the research will investigate the beneficiation and hydrometallurgy of mining waste. In addition to the technical factors, the deposits are evaluated from an environmental, but also from a social and economic point of view.
In addition, we gather regional hydrogeological baseline data to identify groundwater reserves and to form the basis for assessing the environmental impacts of the various stages of mining operations. We will pilot one larger area in the ore prospecting/mine planning phase and, if possible, a few selected mine sites selected to the mineral potential study. From these, a regional hydrogeological review will be made, using GTK's data and open data as the basis.
The created hydrogeological database can be used in planning the sampling of the environmental impact assessment and in evaluating the possible environmental impacts of the reuse of mining waste areas. The collected data can be used later in future projects that utilize advanced data analysis based on artificial intelligence or machine learning.
The processing of tailings is optimized under laboratory conditions
Separating valuables from tailings requires processing and characterization. In the REPower-CEST project, tailings processing and characterization methods are developed and piloted under laboratory conditions.
To optimize the processing of the tailings, new laboratory-scale equipment and analysis equipment, which can be used to better characterize the composition and properties of the tailings, will be purchased. These factors affect mineral beneficiation and hydrometallurgical processing. The acquired equipment will be placed in the Geological Survey of Finland Outokumpu laboratory (GTK Mintec).
In addition, an automated analysis and reporting system (visualization) will be developed, which combines the results of the automatic mineralogy of tailings samples generated in the processing, and the database of mineral properties. This produces a repeatable, systematic identification and visualization of minerals in the tailings stream. Based on the results, estimates can be made of the future circular economy potential of tailings that are currently being formed.
Further information
The Geological Survey of Finland is responsible for the content of this page, as part of the REPower-CEST project.