Sensors Make Sense of Mine Conditions

December 2020
Mapping physical details of mining sites is an expensive, time-consuming, potentially dangerous proposition.

University of Arizona then-graduate student Jingping He was able to further work on an alternate process while getting real-world experience. The 26-year-old worked with hyperspectral sensors in a project led by Isabel Barton, assistant professor of mining and geological engineering. The aim: Determine how useful the sensors could be in monitoring surface mineralogy, materials distribution and moisture conditions at mine operations.

It turned out that Jingping He was well suited for the project, having already analyzed some spectral data as an academic exercise. “I even don’t know where that data came from,” he recalls of that lab work. As a next educational step, he joined Barton’s project. By gathering data from the start at sites he would visit, he could make better conclusions by comparing results with what he knew was out in the field.

His work with Barton and others resulted in a successful thesis that helped Jingping He earn a master’s degree in mining engineering. He also was able to provide information on ground- and drone-based hyperspectral remote sensing, which has been in use for other applications, to mining companies who are considering adopting those technologies.

The traditional method of mapping minerals at a mine is to send people out to chart exposed surfaces and gather mineral samples for testing. It’s a safety risk for the workers, as well as a laborious and expensive process. Deploying remote hyperspectral sensors that read the spectral signatures of minerals is a safer, more cost-effective process. The technology provides a far larger range of spectra—some 300 bands—compared to multispectral remote sensing with its six bands. Improved data processing vastly shortens the time to get results. “It’s definitely a step change in technology,” says Leon DuPlessis, who was the research chief engineer at Freeport McMoRan Inc. at the time of Jingping He’s study.

Hyperspectral remote sensing reveals unusual cause for slope movement

Freeport and ASARCO LLC provided financial and logistical support to the research team, as well as access to their sites for hyperspectral remote sensing tests in different mining environments.

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Jingping He presenting research results
Jingping He presenting at the SME conference

Freeport was already using multispectral remote sensing and wanted to test out the drone-mounted hyperspectral technology on a leach pad at the Safford Mine in southeastern Arizona. The study would check the sensor’s ability to detect moisture, irrigation piping and other non-mineral features. “This really is a case study that defines what it would take and what are the pros and cons,” DuPlessis says.

Jingping He’s work suggested that hyperspectral remote sensing could map material distribution on leach pads, depending on how low the drone flew. For ASARCO, the researchers used tripod- and drone-mounted sensors to scan the highwalls at its open-pit Ray Mine near Kearny north of Tucson, where recent slope movement wasn’t traceable to faults, the usual culprits. He’s research revealed that the cause was mineralogical. A particular type of clay now exposed in the highwall had absorbed water and swollen, making some areas unstable.

Jingping He has presented his findings at conferences of the Society for Mining, Metallurgy & Exploration (SME) and Hydroprocess 2020. “It is good to share what I am focusing on with others,” he says.