A 15-minute read
For Stenman Minerals Ab, a company specialized in providing services of mineral characterization, dealing with high volumes of samples is not very unusual. However, in 2017 the company received an inquiry to analyze 50,000 samples, and Jarkko Stenman, a trained geologist who is running the company, was put up to a challenge. Jarkko’s typical approach of collecting Powder X-ray Diffraction Data (PXRD) using laboratory diffractometers equipped with sample changers was not up to the task, so he had an idea: what if this huge amount of samples can be measured substantially faster using a synchrotron source? The outcome is no less than impressive. The new experimental approach, developed by Jarkko Stenman, Nicola Casati and his colleagues at the Materials Science beamline at the Swiss Light Source, allows for collecting PXRD data on 50,000 samples in only several beamtime shifts.
During his recent visit to the Swiss Light source, we sat down with Jarkko to hear the story how an industry-academia collaboration helped to push the high throughput potential of synchrotron PXRD measurements.
Jarkko Stenman at the Swiss Light Source about to start the experiement.
What does Stenman Minerals do and why?
Jarkko Stenman, COO Stenman Minerals Ab: Both the industry and academia need to be able to characterize geological samples: academics want to validate scientific hypotheses, while companies use the results to target excavations and to improve procedures for mineral processing. In both cases, it is important to discern the type and amount of minerals present in the sample. Stenman Minerals provides this to geo-, material and environmental sectors. We employ a selection of analytical techniques focusing on X-ray diffraction, X-ray spectroscopy and electron microscopy. A common sample characterization includes grounding the sample and analyzing it using a laboratory powder X-ray diffractometer.
How did you end up working with tens of thousands of samples?
Jarkko: A huge amount of samples is actually not that unusual in an industry that is related to mineralogy. For example, ore prospecting can yield a huge amount of samples; furthermore, the industry often characterizes historic samples as well as products occurring during processing of minerals. But yes, 50,000 samples is still exceptional.
Why did you decide to go from a lab into a synchrotron source?
Jarkko: It all started in 2017, when we got an inquiry from the Kevitsa mine to analyze 50,000 samples. It did not take much calculation to figure out that processing these would take more than a year in the lab. Therefore, we needed synchrotron radiation to perform the measurements within a reasonable time frame instead of binding limited resources of a small company for such a long time to a single project.
Getting the beamtime was easy: at the Swiss Light Source I got support from SLS techno trans AG and Nicola Casati, the beamline scientist at the Materials Science beamline. The real challenge was to prepare, ship and measure 45 kg of samples. Nicola played a crucial role here, too.
What did it take to set up the first experiment at the Materials Science beamline?
Jarkko: After the mining company has accepted the quality of a new approach of commonly used analytical method, Nicola and I decided to make a pre-experiment with only 2,000 samples. We had built a new holder for 500 samples, where each sample is loaded into a hole and taped with a polyetherimide (PEI-palstic) band. Nicola and his team built a specific sample-changer robot that was able to rock the holder. This helped us avoid any artifacts due to sample roughness. That, in turn, allowed us to take a shortcut in the sample preparation, as we did not have to ground the samples any further. In order to deal with thick samples, we had to perform the data collection at relatively high energy, 20 keV. We used the PILATUS 6M, a huge 2D detector that allowed us to obtain a full data set within only 13 seconds – including the time it takes to position the sample!
PILATUS 6M detector in the setup at Swiss Light Source.
How did you use the pre-experiment to scale up the measurement?
Jarkko: The pre-experiment was very helpful, and not just because of the new technical solutions. We were able to determine phases in the batch, which helped us set the focus on 35 minerals. From that point on, it was easier to process the remaining samples. It is funny to think that we spent three months preparing the samples and a week to measure them!
How was the data quality in this high-throughput approach?
Jarkko: Having a big 2D detector helped us achieve extremely good data statistics. Such data quality allowed us to identify all the phases in the sample, even when present in low amounts. This is very important, as we are using Rietveld refinement to quantify the phases in the sample. Even with the automatic refinement the accuracy and precision of the results were better than error generally accepted within such refinements.
You went back to the Materials Science beamline many times again, including this September. How are your measurements doing?
Jarkko: Measuring 50,000 samples in one week was a great success, so we wanted to continue with this extremely high throughput approach. Since 2017, I have visited the beamline over ten times, as Nicola and I were eager to further improve the method. For example, in order to obtain better particle statistics we constructed a vibrating sample holder, based on the technique developed for the Mars crawler by NASA. Depending on the sample, we can achieve exposure times as low as 5 seconds. The experimental setup is available at the beamline and it requires only some fine tuning before the measurement.
What is the future of such a high-throughput system for the industry?
Jarkko: The developed a high throughput system is a good example of constructive collaboration between industry and academia. It is based on advanced technologies and designed to support industrial scale volumes of samples, without any compromises in data quality. For industry users, this is a big step forwards, both technically and economically. If you have thousands of samples, it is easier and cheaper to measure them at a synchrotron source than using a laboratory diffractometer!
How do you return to the lab after such a success at a synchrotron?
Jarkko: One of the next challenges is to construct a high throughput laboratory device. I am looking into a big EIGER2 detector, maybe in combination with a microfocus source. I would love to have one of these in the lab!
About STENMAN MINERALS Ab
STENMAN MINERALS Ab provides a variety of mineralogical-, petrological-, geochemical analysis and material characterization services to geo-, material- and environmental sectors in academia and industry. Supported analytical techniques include X-ray diffraction, electron microscopy and X-ray spectroscopy. Company also provides geo-material solutions, mainly laboratory equipment for special needs such as precision sample grinding.
About Materials Science beamline at the Swiss Light Source
Materials Science beamline, X04SA, is powered by a short-period (14 mm) in-vacuum, cryogenically cooled, permanent-magnet undulator, (CPMU, U14), while the front end and optics are designed to optimally exploit the characteristics of the U14 source. The beamline features two end stations. Powder Diffraction station offers high resolution and high throughput PXRD, and it is equipped with the MYTHEN 24K detector. In situ surface diffraction station features the PILATUS 6M detector.
About DECTRIS detectors for powder X-ray diffraction
DECTRIS develops and manufactures high-end X-ray and electron detectors. Its product portfolio for powder X-ray diffraction applications includes a 1D and 2D detectors, optimized for the use in laboratories (R series) and at synchrotron sources (X series). MYTHEN2, PILATUS3 and EIGER2 detector families are found at leading beamlines, as well as in laboratory diffractometers produced by major equipment producers: Bruker, GNR, MRX, Proto, Shimadzu, STOE, Stresstech, X-ray Eigenmann, and Xplorex.
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