By Victoria Martinez and Lucinda Wood
Whether in potash slimes, oil sands or in kimberlite slurries, active clay minerals can cause serious issues in many plant operations. For industries where clay minerals are present, a better analytical approach is needed to more quickly and accurately measure these minerals.
In response to this, experts at SRC’s Pipe Flow Technology Centre™ developed an Automated Measurement Platform (AMP) that provides accurate, real-time, measurement of clay minerals.
Industrial processes are affected by the reactivity of the clays present, and how those clays interact with cations in the environment—this is known as the cation exchange capacity (CEC). Depending on what clays are present in an ore, the reactivity or CEC can vary, ranging from small in “inactive” clays, such as kaolinite, to very large in “active or swelling” clays, such as smectite.
Particularly where there is a solid-liquid separation process or pumps, the amount and CEC of the clay minerals present can lead to significant operational problems.
“As soon as a mine has an active clay in it, there’s probably going to be a problem, and it’s going to be a big problem,” said Jennifer Bentz, SRC research scientist, who works at its Pipe Flow Technology Centre™. “It can cause a shutdown or a stop to production to fix the issue or clean it up.”
In certain applications, active clays are beneficial, like at foundries where they are a key component of molds made with a compound mixture called “green sand” that are used for metal casting. Active clays are also used in cat litter because of their exceptional absorbent and clumping properties, and in water and soil treatments to adsorb contaminants from the environment, such as heavy metals, organics, industrial dyes and radioactive isotopes.
They can also be used as liners for landfills, tailings ponds, and heap leach processes due to their very low permeability, which prevents contaminants from escaping into the environment.
Whether a challenge or benefit, it’s important to measure clays
Clays are difficult to measure because they are small and share a similar crystal structure to each other, despite significant differences in CEC.
This means that many of the traditional analytical methods used to measure them (e.g., X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Short-Wave Infrared Reflectance Spectroscopy (SWIR), and particle size) require intensive sample preparation to get accurate data, sophisticated equipment, and robust chemometric models to resolve overlapping patterns.
And this is where SRC’s AMP comes into play. The AMP combines automation and a tailored spectroscopic analytical technique to make on-site measurements of CEC using a cationic dye simpler, faster, and more precise.
Applications for other industries
Beyond mining, the Automated Measurement Platform could be beneficial to the foundry industry, which use active clays like bentonite in their green sand molds. They regularly measure clay levels to adequately refresh the spent green sand.
Automating the CEC (or clay) measurements with the AMP could make foundry processes more effective and reduce waste, helping lower costs by maximizing the reusability of the sands throughout the production cycle.
SRC is also looking at applications for the AMP beyond clay measurement.
With an established reputation in potash in Saskatchewan and beyond, the potash industry is one key area SRC is looking to support with the AMP.
For potash processing, insolubles—in this case, clay minerals that aren’t necessarily active—can pose challenges. Insolubles in the brine, especially if clays are present, affect separation and flotation, absorb chemicals, and decrease recovery. They may clog filters, wear down equipment and require more reagents.
In tailings management, getting near real-time data on the clay content of tailings can aid in determining optimum flocculant dosages and prevent settling issues in the tailings.
The AMP also has potential in several applications beyond active clay and insoluble particle detection. It can be configured to perform other analytical measurements, including pH, conductivity or water hardness.
“We can really tailor it to perform a wide range of automated analytical measurements,” Bentz said. “It just takes beta testing, and making sure all the sequencing within the platform happens in the right order and that it’s optimized for the client.”
This is a condensed version of a longer article. To read the full article, visit www.src.sk.ca/blog.
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