Radiation free breakthrough in tailings pipeline monitoring promises safer real time density checks without losing accuracy or operational efficiency

At the Life of Mine | Mine Waste and Tailings Conference 2025 in Brisbane, University of Queensland PhD candidate Yue Xiong unveiled a promising alternative to radiation-based monitoring of tailings slurry pipelines - one that could make real-time density measurement safer, cheaper and more adaptable across mine sites.

In his paper Non-invasive and Real-time Monitoring of Tailings Slurry Density in Transmission Pipeline Using the Electrical Resistance Tomography Method, co-authored with Chenming Zhang, Sebastian Quintero, Naresh Racha, Thierry Bore and David Williams, Yue presented research into applying electrical resistance tomography (ERT) to measure the cross-sectional density distribution of tailings slurry in pipelines.

Currently, nuclear densitometers are widely used for this purpose. While highly accurate, they pose radiation hazards that can limit their use. “Computed tomography is precise, but the radiation risk is real,” Yue told delegates. “That’s why we explored non-invasive alternatives.”

Why the industry needs a new approach

Tailings - waste material left after mineral extraction - are typically transported as slurry through pipelines to storage facilities. Flow properties are critical: too thick and too slow can cause blockages, too thin and too fast wastes energy and water. “Real-time monitoring is essential for optimising pipeline operation,” Yue explained.

The team evaluated several non-invasive options, including PET, MRI, ultrasonic, optical and infrared sensing. “ERT stood out for its safety, low cost, and strong adaptability to slurry,” Yue said. While ERT is commonly used for mapping the resistivity of soils, it had never been validated for monitoring tailings slurry density - until now.

How it works

An ERT system uses electrodes arranged around the pipe to inject small currents and measure voltage. These readings are used to reconstruct an image of the slurry’s electrical conductivity, which can then be correlated to solids concentration.

To calibrate the method, the researchers used tailings sourced from a Queensland mine - 31% clay (mostly kaolinite), solids specific gravity of 1.78, and process water conductivity of 0.15 S/m. Slurry samples with solids concentrations from 15% to 35% by mass were prepared, and water conductivity was varied from fresh to highly saline conditions.

“The relationship was clear - slurry conductivity increases with water conductivity, and we could establish reliable calibration curves,” Yue said. Interestingly, clay content at these concentrations had minimal impact on conductivity when pore water conductivity was low.

Putting it to the test

The team built a full-scale dam break test rig at UQ’s Long Pocket campus, using a 200 mm diameter pipeline - the same size as those used in situ. In the tests, 1 m³ of slurry flowed through the pipeline past the ERT sensor, with solids concentrations adjusted in increments from 25% to 35%.

In each run, 1,000 stable-stage ERT frames were analysed. “The differences in the signal curves were distinct, and ERT clearly detected changes in concentration,” Yue said. Predictions based on ERT measurements matched actual values within 3% absolute error.

What’s next

The next stage will see the ERT system deployed at an operating mine for direct comparison with a gamma-ray densitometer. “We’ve shown ERT is feasible for real-time, non-invasive monitoring of tailings slurry density in the lab,” Yue said. “The in-field trial will confirm how it performs under real operational conditions.”

If proven, ERT could give mining operators a practical, radiation-free option for monitoring tailings pipelines - reducing health and safety risks without compromising accuracy.

Pictured: Yue Xiong presenting his research on electrical resistance tomography for safer tailings pipeline monitoring at the Life of Mine | Mine Waste and Tailings Conference 2025 in Brisbane. Photo: Jamie Wade.