TECHNOLOGY

InSAR and tailings: Scratching the surface

Applications of InSAR (Interferometric Synthetic Aperture Radar)technology have expanded far past the uses that scientists initially envisaged when the first InSAR satellite, the ERS-1, captured surface deformation caused by the Landers, California earthquake in 1992.

 Synspective’s "StriX-α" has taken a SAR Sliding Spotlight image of The Chuquicamata Mine, Chile

Synspective’s "StriX-α" has taken a SAR Sliding Spotlight image of The Chuquicamata Mine, Chile

InSAR technology today is still being used to study the impacts of natural events such as volcanoes, landslides and ice dynamics, but also for far more human phenomena like battlefield intelligence and illegal building. 

While data from SAR satellites is not visually straightforward, it encapsulates great values. InSAR is a geodetic method that uses multiple SAR images to generate maps of surface deformation or digital elevation, using differences in the phase of the waves returning to the satellite. The technique can potentially measure millimetre-scale changes in deformation. 

The ability to continuously monitor ground deformation has certainly piqued the interest of mining companies, and InSAR is already being used around the planet to detect gradual movements or deformations that may indicate underlying problems in tailings dam structures. 

But while this early detection could prompt necessary actions, such as inspections, maintenance, or reinforcement, can InSAR provide enough timely information to prevent a catastrophic failure? 

Mining Magazine discussed this and other questions with Keizo Fujiwara, solution platform executive officer, at Tokyo-based InSAR-focused firm Synspective. 

Synspective launched StriX-1, its third SAR satellite, into its target orbit last September 16. StriX-1, which was deployed by Rocket Lab's Electron at Rocket Lab Launch Complex 1 on New Zealand's Mahia Peninsula, has a sun-synchronous orbit (SSO), with an altitude of 561km. 

Q: Previously, satellites have provided infrequent updates on tailings dams, perhaps once a week. Is it possible to integrate real-time data with satellite monitoring for more comprehensive insights?

A: Currently, satellite observations occur once every week or two, providing an overall picture. Many mining sites lack instrumentation, making it challenging for mining companies to determine where and how much to invest in sensor installation. Satellites can help scan the entire area and identify high-risk regions, allowing companies to prioritise accordingly. As satellite frequency increases, we aim to provide not only long-term monitoring but also timely detection of rapidly growing risks. Our objective is to work with partners to install ground sensors and deliver consistent and meaningful insights to customers by integrating satellite and ground data. 

Q: The area of satellite monitoring for tailings is advancing quickly - why and how has your company started work in this area?

A: As a startup, we are focused on building SAR satellites, specifically in the 100-kilogram class. Our goal is to surpass traditional operators by offering higher resolution and more frequent imaging. We not only build and operate these satellites but also sell the imagery and process it to provide meaningful insights and data. SAR satellites are widely used in defence and intelligence applications due to their ability to penetrate clouds and monitor ground activities day and night. While these satellites are already being used in various locations around the world, including Ukraine and Russia for example, our mission extends beyond that. We aim to create a sustainable world and contribute to society by commercialising and democratising these technologies for broader use cases. Mining is one area where we are striving to achieve this goal. 

Q: If the tailings facilities are remote, can your satellites still monitor them? How often do they pass over such areas?

A: Our satellites are typically in an SSO, meaning they return to the same position daily. The satellites cover many parts of the regions on the earth. As we build the constellation, the frequency of the revisit is going to increase. 

Q: So, for ground deformation sensing and processing in mining, is the approach similar to other civilian applications?

A: Yes, the analytical techniques used in mining, such as interferometry analysis, are similar to those employed in other applications. InSAR has been utilised in commercial applications, including mining, using satellite, airborne, and ground-based technologies. With advancements in satellite capabilities, such as increased frequency and higher resolution, the potential for satellite-based solutions in mining is growing. Mining companies recognise the benefits of automation and the use of satellite technology, especially with more frequent observations. 

 

Q: Does the processing and decision-making in your satellite monitoring require the use of AI or machine learning?

A: There are two main steps in our processing. Firstly, when we observe from space, there may be inconsistencies with ground sensor data. We work to improve the accuracy and consistency of analytical results by incorporating data from ground sensors. This iterative process helps refine the data and improve results and could be an area where AI is able to play an increasing role. Secondly, once we have consistent data, AI and machine learning techniques are used to correlate and interpret the data. We collaborate with experts who specialise in sensor data interpretation and leverage their domain knowledge to manage and analyse large datasets effectively. 

SAR, combined with data from other sources can also help mining firms with their stockpile monitoring as SAR satellite images can show changes in stockpiles as small as just 3m. Combine this with a machine learning model to quantify any changes and mine operators can be automatically updated with information that lets them make crucial trading decisions quickly. 

Q: If an early adopter finds InSAR for tailings dam monitoring cost-effective, could they potentially expand its use for other applications, such as measuring stockpiles or optimizing routes?

A: Yes, they could. InSAR can be utilized for various types of data analysis and detection methods depending on the specific requirements. For instance, when monitoring the deformation of tailings or surrounding areas for gradual changes like landslides, interferometry is an effective analysis technique. However, in cases where there are sudden collapses or large-scale landslides, alternative algorithms can be employed. Additionally, mining companies often have an interest in monitoring the growth of ponds or tailings, which can be accomplished by measuring the water surface area. By combining different techniques, valuable insights can be provided to mining companies. 

Q: Could SAR be used to assess the size and economic growth of mines?

A: It is indeed possible to use SAR to gather economic data on the size and growth of mines. However, there are instances where optical or other methods may be more suitable for detecting certain changes in mine size. Each situation may require a tailored approach to achieve accurate measurements. 

Q: In the future, could SAR potentially contribute to fleet management and route optimization within mining operations?

A: That is certainly a possibility. Although not yet implemented, there are ideas to involve SAR in fleet management and optimization. By tracking trucks and monitoring their loads, it may be feasible to find optimal routes and improve operational efficiency. Additionally, in scenarios where mining companies use train tracks for material transportation, InSAR could be employed to assess the stability of the land and identify potential risks of collapse, offering assistance in such situations. 

Satellite monitoring can also help keep track of production levels by providing accurate calculations of the size of pits to help maintain an index of mining production. The resolution of the imagery provided is so good that the use of heavy equipment on site can be monitored from space. This is especially important at a time when increasingly larger equipment is being used in mining operations.

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