Monitoring & metering


meet this challenge, a small start-up business in Finland, Sensmet, has developed an online monitoring technology that promises a step- change improvement in both the manufacturing and recycling of battery metals. Sensmet CEO Dr Toni Laurila, explains: “We bring the analytical performance equivalence of laboratory ICP-OES next to the production process where real-time metal concentration results are acutely needed. In comparison with laboratory analysis, Sensmet’s technology provides robust, fully automated online measurement, which offers enormous advantages for process management and quality control.” Traditionally, battery metal manufacturers have had to rely on batch sampling and laboratory analysis in order to control their processes, but typically this incurs a delay of four to 10 hours. Sensmet has therefore developed a breakthrough online technology; Micro- Discharge Optical Emission Spectroscopy µDOES, which is able to measure multiple metals, including alkali metals, such as any battery metal and their impurities, in real-time. Laboratory analysis can take several hours for a sample to be collected and analysed in a laboratory, which means that process managers are unable to adjust dosing of chemicals efficiently. Consequently, raw materials are wasted and product purity - the most important product quality - is difficult to control, which is especially important because impurities significantly affect the performance of Li-Ion batteries. Sampling for laboratory analysis is also laborious, expensive and often rather challenging to reliably arrange 24/7. For all of these reasons, continuous monitoring has long been the dream in lithium manufacture, so with successful trials at several plants, the industry is delighted that the dream has become reality.


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CONTINUOUS MULTI-METAL MONITORING TECHNOLOGY Sensmet's µDOES enables the multi-metal real- time analysis of aqueous samples. In addition to lithium manufacture, the technology is also suited to the ‘black mass’ recycling of battery metals. The patented µDOES technology is based on atomic emission spectroscopy. A micro-discharge (electric spark) is created directly inside the aqueous sample, causing a microscopic volume of the fluid surrounding the spark to be flash- heated to 10,000°C. Molecular species in the micro-discharge are dissociated into atoms, which are excited to their respective higher electronic states. Upon returning to their ground state, these atoms release their excess energy by emitting light at their characteristic wavelengths. The µDOES measures this atomic emission spectrum to derive quantitative analysis of the metals contained in the sample.


Data from the µDOES analyser are displayed locally showing the concentrations and trends for


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s global effort to fight climate change intensifies, the challenge for battery manufacturers and their supply chains is to find ways to meet the rapidly growing demand for electric vehicles (EVs). To help


BREAKTHROUGH TECHNOLOGY FOR LITHIUM MANUFACTURE


each metal, and alarm levels can be set for each element. Results are transferred digitally to users’ databases and/or the cloud.


In hydrometallurgical processes which cannot be controlled by monitoring pH, direct measurements of dissolved metal concentrations are essential. There are alternative methods of monitoring, but all of these have major limitations. For example, online XRF is unable to measure light elements such as lithium and sodium, and it is almost impossible to calibrate XRF for low concentration impurity measurements.


ADVANTAGES OF CONTINUOUS MONITORING


Given the large sums of money involved in lithium manufacture (raw materials and final product), the accurate dosing of precipitation chemicals is extremely important. For example, when sodium carbonate is added to a slurry containing beta spodumene under high temperature and pressure, lithium carbonate and analcime solids are formed. If insufficient sodium carbonate is dosed, some of the lithium will not react to form lithium carbonate, and unreacted lithium will be lost in the side product analcime sand. This is extremely undesirable because it represents a loss of revenue. Overdosing is also undesirable because it would result in a waste of process chemicals. Continuous monitoring is also vital for the reduction of battery metal impurities such as sodium, potassium, copper, zinc and calcium; all of which can be measured by µDOES at any stage of the hydrometallurgical production and recycling process. Strict monitoring and control can therefore reduce the impurity levels and thereby prevent the cost and delay incurred by retreatment.


LITHIUM PRODUCTION FROM SPODUMENE Keliber ran a pilot-scale test programme in 2022 to evaluate the µDOES analyser in the continuous optimisation of precipitation


chemical dosing during lithium production. Nearly 80 samples were drawn from the process with sodium and lithium


concentrations analysed in parallel using both the µDOES continuous analyser and a laboratory ICP-OES. The results showed an excellent degree of correlation between the methods. Keliber’s Sami Heikkinen says: “Chemical dosing based on reliable real-time data brings stability to the process, which is very important because it avoids drift and optimises both yield and quality while minimising cost.”


CONCLUSION


The switch from fossil fuels to electrically powered vehicles and renewable energy has dramatically increased the importance of battery technology. This, in turn, has created a major challenge for battery manufacturers and their supply chains. Consequently, there is a high demand for new technology that can help improve the quality and efficiency of production. As the EV market develops, and global battery metal resources start to dwindle, there will be an even greater emphasis on the recycling of used batteries. Again, the online µDOES analyser will help provide a solution because the processes involved with black mass recycling have to be closely monitored and controlled. The Sensmet µDOES represents a breakthrough technology that will help the battery industry to realise its dream of effective process and quality control. The ability to conduct continuous, simultaneous measurements of multiple metal species in an aqueous matrix offers battery metal manufacturers the opportunity to improve process efficiency, lower costs, increase throughput, and improve the quality of the final product.


Sensmet www.sensmet.com April 2023 Instrumentation Monthly


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