Monitoring & metering


identified water management, waste minimisation and ecological impacts as material issues within its sustainability strategy. A water treatment plant was built at the Sotkamo facility in 2021, using lime to raise the pH of site wastewaters and remove contaminants such as metals. In compliance with an environmental permit, together with Finnish environmental law, high quality process monitoring ensures the receiving environment is not polluted by the discharge, and includes an upper limit for nickel in the receiving river water of 0.034 mg/l. During the period immediately after the installation of the neutralisation plant, a large number of laboratory samples were taken as the plant was optimised. This prompted Elementis staff to investigate the possibility of continuous analysis, which led to the trial of Sensmet’s µDOES analyser.


CONTINUOUS MULTI-METAL MONITORING TECHNOLOGY Sensmet’s Micro-Discharge Optical Emission


Instrumentation Monthly August 2024


Spectroscopy, µDOES, enables the multi-metal real-time analysis of aqueous samples. In addition to nickel monitoring, the technology can also be utilised to monitor elements such as lithium, sodium, cobalt, manganese, nickel, copper, and more.


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. Molecules 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 sample, displaying measurements locally, and transferring data to the user’s DCS and database as needed.


CONCLUSIONS


The µDOES analyser has provided the Sotkamo staff with new insights into the factors affecting nickel levels, which enables the development of mitigation measures. “Sensmet’s continuous monitoring technology has delivered a real lightbulb moment for us,” Jari Sirviö explains. “Now that we know about the correlation between rainfall and nickel concentration, we can investigate a range of options that could be employed to lower nickel levels, and with continuous monitoring we will be in a better position to evaluate the results.” In recent years there has been a global trend toward greater use of continuous environmental monitoring. “This has been enabled by advances in technology,” explains Sensmet CEO Dr Toni Laurila. “However, as this trial has demonstrated, continuous monitoring delivers a range of other important advantages, that combine to further improve environmental protection.”


Sensmet www.sensmet.com 71


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