STINGS - An Integrated Novel Approach for Tailing Supervision

STINGS is an innovation project funded by EIT Raw Materials to establish a ground- and space-borne remote sensing and analysis system to effectively and cost-efficiently monitor critical ground infrastructure stability and content, primarily focusing on mining tailing dams. It is dedicated to increasing the safety standards related to tailing operations and to delivering the related mining sector, government, citizens and all stakeholders affected by previous and current activities with an extended monitoring and early warning system for identification of operational impact and environmental risk.

Global data on failures of both operated and closed tailing dams are extremely scarce and incomplete, much of this due to differences in legislative reporting requirements and to some degree as a reflection of willingness of failure reporting. Nevertheless, available data shows that there has been a significant amount of tailing dam failures during the last decades. Data shows that the number of very serious and serious (both including loss of life) failures are increasing. This is mainly driven by larger tailings becoming necessary to allow economic extraction of lower grades of ore. This tendency is predicted to continue at a rate of at least 1 - 2 major failures every year from 2017 - 2020. Increasing global mining operations need the availability of new technologies to monitor tailings safety effectively and cost-efficiently. Here, a key value STINGS will provide is the intersection between the increasing risks of tailing management and the improved technologies of monitoring.

By integrating and analyzing a broad range of complementary ground- and space-borne sensor data, STINGS offers a unique information service to identify risks, prevent disasters and to capture previously undetected secondary values. The monitoring system will focus on different information types and different sensors and combine them in order to generate the most reliable information related to tailings stability, chemical and mineralogical content. It will implement satellite radar information as well as ground-based sensor data to detect mechanical movements. An additional integration of optical remote sensing information enables to detect observable exits of substances from tailings. By using these different kinds of sensor information, data analysis and modelling the system will create safety information relevant for early warning. STINGS will offer cost efficient performance improving automation for monitoring of both active and closed tailings sites while providing a holistic risk management tool helping monitoring operations to ensure both measuring as well as analyses and reporting.

The technical feasibility of STINGS developments strongly depends on the underlying technical components. Satellite radar interferometry is a cornerstone of remote sensing. The European Union (ERS 1, ERS 2, ENVISAT, and now Sentinel 1A and B) and Germany (SRTM, TerraSAR-X, TanDEM-X mission) are leading players in this field of technology. In this project in particular, differential interferometry (dInSAR) is of interest in order to detect and monitor surface deformation occurring at tailings. For this application, the capabilities of the current operational European and German radar satellites are complementing quite well. Furthermore, radar absorption methods are investigated by STINGS to identify soil moisture changes by multi-temporal analysis of SAR-Data from Sentinel 1 as an indicator for the potential dry out of tailings. The results can be used as an early warning signal for particle emissions by wind from the tailing pond. In addition, the same methodology is foreseen to be applied for the detection of ground moisture changes due to leakages of liquids from the tailings pond. Optical Remote Sensing with data namely from the Copernicus Sentinel 2 mission and hyperspectral missions (e.g. Hyperion, EnMap) represents a keystone of the planned system.

Optical remote sensing is already applied for exploration and monitoring tasks in the mining sector. Recent results from R&D-projects clearly demonstrated the potential of new optical space-borne data from missions like Hyperion and Sentinel 2 e.g. for change detection of water bodies and soil moisture due to mining-related ground movement.

In-Situ sensor development and sensor application to detect movements and instabilities at tailing sites is another major task in STINGS. While various sensors (GNSS) and data logging technology are available on the market, within the project we focus on the development of low cost equipment with automated communication technology (ICT) for automated sensor data transfer.

System and data integration is a main challenge of the digital edge and specifically for what is called “Industry 4.0” – a collective term embracing a number of contemporary automation, automatic and intelligent data exchange and fully digitized manufacturing technologies. STINGS will provide an important part corresponding to the integration of the various systems for the proposed interdisciplinary monitoring of tailings. The data management and early warning system developed during the project will accumulate all information and create safety information about the supervised tailings. The system is based on DMT’s monitoring system SAFEGUARD that provides a technical foundation and proofs the technical feasibility.

The partner composition of STINGS combines user partners to determine market requirements, industrial partners for commercialization and the thematic expertise of scientific institutions. DMT takes the role as consortium lead due to the company’s long-term widespread international experience in the development of monitoring technologies for the mining industry. To improve tailing monitoring specifically in Latin America, one of the core project partners is PUCV (Pontificia Universidad Católica de Valparaíso) from Chile. PUCV has already conducted intense research focusing on improving operational controls and generating technologies for recovering areas occupied by tailings deposits. Within STINGS, the university will give valuable technological input, enable to select a suitable site for the system developments at large local tailing operations and will evaluate the results of the system for use in Chile.

Karsten Zimmermann
DMT GmbH & Co. KG