Hyperspectral imaging in mining: Boosting efficiency and enhancing sustainability
Hyperspectral imaging (HSI) offers the mining industry an innovative solution that can drive business value, sustainability, and operational efficiency. While the technology is mostly adopted in mineral exploration via the use of hyperspectral core scanners, high-quality camera systems offer many benefits within operational mining and post-mining landscapes. HSI can provide detailed information on the composition and distribution of minerals and other materials within a geological context. The technology facilitates rock and mineral mapping and characterisation, can resolve surface patterns indicative of subsurface activity and map environmental changes such as vegetation health and changes in surface pH.
Using different HSI tools along the life of mine and mining value chain enables mining companies to identify and evaluate extracted materials as well as geospatially monitoring the areas in their care, adding to existing point-based information from drilling or sampling. Benefits include product quality control, grading, close-to-face sorting, tailings monitoring, waste processing and rehabilitation. It ensures that mining activities adhere to regulatory standards and produce consistent, high-quality outputs.
Usage of HSI promises to reduce operational costs by providing faster results than traditional methods and by ensuring consistent ore grading and mine planning. Besides primary raw materials, HSI already plays a critical role in the secondary raw materials sector as the technology supports recycling and repurposing of mining by-products and consumer end products. Here, we present how HySpex hyperspectral cameras are becoming a vital tool for mining operations seeking to balance profitability with ecological stewardship, and give examples of successful HSI utilisation along the mining value chain.
Principles of imaging spectroscopy
Hyperspectral imaging, also known as imaging spectroscopy, combines two techniques: digital imaging and light spectroscopy. In addition to the spatial information, a hyperspectral pixel contains a continuous spectrum with hundreds of different wavelengths (or bands). An image generated in this way provides spectroscopic information for each pixel of the scene, which can be used to identify, classify or quantify the materials in the scene according to their spectral ‘signature’.
In mining applications, hyperspectral cameras can be mounted on heavy-duty tripods, uncrewed aircrafts and aeroplanes, over conveyor belts and other conveying platforms, in mobile laboratories, over truck-loading or weighing stations and in many other locations. The cameras are versatile, flexible and robust. They only need to be in the line-of-sight of the object and with solar or artificial illumination active in the visible to near-infrared (VNIR; 400-1,000nm) to shortwave infrared (SWIR; 1,000-2,500nm) to capture reflected information from the surface. The spatial imaging context of the data allows geologists to get a bigger picture of the data, literally, reducing potential inconsistencies stemming from sampling errors for other geochemical and mineralogical methods.
With HSI cameras operating in the VNIR and SWIR wavelength ranges, rock material from all stages of the mining value chain can be investigated by studying the characteristic absorption features, inflections, and signature slopes of the individual (pixel) spectrum captured by the imaging system. In geological environments, absorption features detected in the VNIR arise from transitional elements, including iron-bearing minerals and rare earth elements (REEs), while the SWIR region is commonly used for identifying alteration mineral assemblages related to hydrothermal systems of base and precious metal deposits. The mineral groups that can be detected and mapped in the VNIR-SWIR wavelength regions include carbonates, sulphates, sulfosalts, clays, and phyllosilicates such as chlorite, talc, and muscovite.
New heights in hyperspectral core scanning
The HSI technology, firmly established in core scanning technology, has provided valuable lessons for high-resolution mineral mapping. Hyperspectral core scanning is a non-destructive and time-efficient solution to characterise the alteration footprints of ore deposits. Selected for providing unrivalled datasets with high spectral quality, fidelity, and precision, HySpex Classic VNIR-1800 and SWIR-640 cameras are now also being integrated with Midwave infrared (MWIR; 2,600- 5,500nm) and Longwave infrared (LWIR; 5,500-12,500nm) cameras, yielding data cubes with a combined spectral range of 400-12,500nm. A 3D profiler for surface modelling allows for precise spatial co-registration between all sensors on the core scanner platform. The core scanning platform is optimised to handle high throughput of single to multi-row cores in plastic, cardboard, or wooden boxes, and can also handle drill chip boxes, loose samples, and rock mass. The HSI will generate high-resolution RGB sample images, high-density mineralogic spectral data cubes, and 3D laser profile datasets.
The Breeze Geo software developed by NEO and Prediktera allows for efficient data acquisition, logging, and analysis. Mineralogic output is based on an expert system from the U.S. Geological Survey, but Breeze Geo affords users the additional ability to adjust and adapt with new incoming knowledge from geochemistry, for example, and can evaluate in real-time if and where sampling for validation and interpretation purposes is advised. The resulting mineralogic interpretation and logs can be exported in common formats to be included in other modelling software such as IoGas, Imago, or Leapfrog, which makes it easy to integrate into existing workflows.
HySpex cameras are incorporated into numerous core scanning systems supplied by various service providers globally, producing valuable digital records of core and chips for mineral exploration.
In a 2021 article, BHP announced a significant breakthrough in extending the lifespan of an iron ore mine with hyperspectral technology, implemented by one of NEO’s original equipment manufacturer (OEM) customers. While it is clear that hyperspectral technology can enhance mining efficiency and promote more sustainable production, the ability to extend the operational life of a mine marks a major advancement, solidifying the technology’s role in the mining industry. The article mentions that BHP’s iron ore team developed algorithms to analyse hyperspectral images, identifying the areas of Yandi’s geology that could be most effectively processed to separate saleable iron ore from waste material.
