Dr. Jiaqi “Jackie” Jin: Advancing Mineral Characterization with 3D X-ray Microscopy
Dr. Jiaqi “Jackie” Jin, professor of Metallurgical engineering at the University of Utah, bridges industry experience with cutting edge academic research to tackle some of mining’s toughest challenges. His research focuses on 3D microstructural characterization, surface chemistry, and particle-level analysis of minerals—work that earned him the prestigious 2023 Freeport-McMoRan Career Development Grant in recognition of his impactful contributions.
Today, advanced 3D X-ray microscopy is revolutionizing how critical materials in mining and mineral processing are studied. At the University of Utah, Dr. Jin’s team is leveraging Sigray EclipseXRM-900 to uncover the intricate 3D morphology, porosity, and internal features of geological and particulate samples. Due to the decreasing quality of still-available mining deposits, data-driven precision is needed to evaluate the potential profitability of potential mines and to develop the approaches that can maximize mine yields.
Installed in late 2023, the Sigray EclipseXRM-900 3D X-ray microscope, became the cornerstone of the lab’s mineral characterization work. With its patented architecture, featuring an open-type X-ray source and a large high-resolution detector, the system achieves an extraordinary 0.3 µm (300 nm) true spatial resolution, enabling analysis which were previously impossible at this level of detail in mineral characterization studies.
“The important part [of our work] is about image processing and analysis,” said Jin. “Besides the fancy-looking 3D pictures, what quantitative information can you extract out of the scans?” That’s what the past 30 years have been about for the metallurgical engineering team at the U: to develop the expertise and algorithm to run the analysis, “so that they [scans] actually provide value.”
18 months on, it is time to revisit Dr. Jin’s work and examine the results. Has his team managed to extract the quantitative information that he had hoped to get. What breakthroughs have emerged, and how has this advanced the understanding—and optimization—of mining processes?
Studying particle morphology – Impacts flotation strategies
Molybdenite (MoS2) is a flaky molybdenum (Mo) sulfide mineral that exists in its natural form as a layered sheet. To produce a molybdenum concentrate for refining (critical for strengthening steel alloys and for electronics), froth flotation of ore particles is often used. In flotation, particles smaller than 100 um were placed in a large bath that has air bubbles that selectively adhere to exposed hydrophobic minerals, effectively separating MoS2 from the gangue minerals (mostly silicates). Molybdenite tends to cleave into thin plate-like particles that have different shapes and surface properties depending on their orientation (hydrophobic faces vs hydrophilic edges) and can behave quite differently in flotation. Conventional chemical assays or even 2D images can’t capture a particle’s true 3D shape, but high resolution 3D x-ray imaging can.
Porosity in Backfill for Underground Mining
In underground mining operations, after ore is removed, it’s common to pump a mixture of tailings (finely ground waste rock) and binders back into the void – this is called backfill, and it serves to both stabilize the ground and dispose of tailings. The effectiveness of a backfill material depends on its porosity and pore connectivity, which influence both its mechanical strength and how water moves through it. With EclipseXRM, Jin’s team can image backfill samples in 3D, seeing the arrangement of particles and the pores between them. Features such as air pockets are weaknesses in backfill structure that could suggest improvements in the mix recipe to eliminate those weaknesses. Moreover, the XRM quantification of pore networks provides estimates of permeability of the backfill – important to predict whether water will drain or pressure will build up in a filled stope. In this way, EclipseXRM provides safety and environmental benefits, helping mining engineers ensure that backfilled areas solidify properly and remain stable over time, preventing accidents and improving mine sustainability. Video 2 is a billet of back-fill material from a copper mine with a porosity of 2.39%. Based on pore size analysis using the local thickness function of ImageJ, there are 58% of porosity by volume having a pore diameter smaller than 100 µm (dark color in Video 2), but the relatively larger spherical pores (brighter colors in Video 2) could result in heterogeneous mechanical properties across this 3D volume.
Solution Mining – Understanding Underground Phenomena
Solution mining is an approach in which fluids are injected to dissolve the minerals of interest and bring them to the surface.
A major challenge in solution mining is predicting how the injected fluid navigates through the ore body – Does it flow uniformly and dissolve all the valuable minerals? Does it get channeled along cracks, creating unintended voids? Does the cavity grow upward, risking a collapse? These questions are hard to answer because the process happens out of sight, deep underground. Here again, EclipseXRM provides a way to bring the subsurface process into the lab. Jin’s team obtained potash core samples – cylinders of the ore taken from exploration wells – and scanned them at high resolution. These cores often contain not just soluble salts, but also insoluble clays or other minerals. The X-ray images showed, in fine detail, the initial pore spaces and cracks in the potash core. The team could distinguish the potash KCl from salt NaCl by different attenuation because of the higher atomic number of K.
Video 3 is a piece of salt core imaged by X-ray computed tomography to identify the NaCl phase (transparent) from the KCl phase (colors). The red structure is the connected KCl phase through this 26.5 µm × 18.8 µm × 9.7 µm volume (22.2%), and the yellow structures are the KCl phases isolated by NaCl salt (1.8% by volume).
Value of EclipseXRM in Natural Resource Research
EclipseXRM has significantly accelerated Prof. Jin’s research, shifting the focus from data acquisition to insight extraction. Not only has XRM played an instrumental role in mineral processing research, Prof. Jin’s team is also successfully deploying this system in adjacent fields of oil sand, oil shale, CO2 underground storage, multiphase alloys, additive manufacturing, and battery materials (https://profiles.faculty.utah.edu/u0738512).