Today, advances in technology and on-line analysis have seen a shift away from quality-focused control to process control. Quality remains vital, but now it’s easy to measure in real time thanks to cross-belt analysers and other on-line instruments. The new frontier is process control, where maximising efficiency becomes a real target rather than an impossible idea.
However, Malvern Panalytical argues that some initial on-line instruments came with downsides. “Running analysis in an enclosed laboratory setting means that all staff are highly trained and aware of how to operate the instrument, but in a busy mine or processing plant, a much wider variety of employees might interact with the instrument. Radiation from continuously running analysers became a serious hazard until more advanced technology was developed, such as pulsed fast and thermal neutron activation – PFTNA.”
PFTNA uses an electrical neutron source to provide highly representative real-time elemental analysis of material, generally passing through the analyser on a belt. “This is especially relevant in mining applications, when low-grade ores may be mistakenly discarded as waste without sufficiently accurate analysis. The electrical neutron source can be switched off easily for maintenance or whenever required, making PFTNA much safer for use in a production or processing environment compared with always-on instruments.”
As an example, highly accurate analysis adds significant value in nickel mining. The predominant source of nickel is lateritic ores, which generally contain only a small percentage of nickel by weight. Separating nickel from the abundant iron content takes care and precision to avoid waste and is a resource-intensive process. PFTNA technology makes this initial analysis for sorting, grading, and blending ore much easier, not only due to its high sensitivity but also thanks to the real-time results that are returned.
At the PT Vale operation in South Sulawesi, Indonesia, plans are underway to install a Malvern Panalytical CNA Pentos cross-belt analyser for this exact application – thanks to very good results already delivered later in the process. A CNA Pentos instrument has already been in use monitoring the kiln feed for several years, ensuring that the level of nickel in the dry kiln product is maintained at ~1.91%, as well as tracking moisture content. The new instrument will enable PT Vale to combine their low- and high-recovery ores at the stockpile without compromising the consistency of their raw material.
Malvern Panalytical: “This also brings extra value in today’s climate of high energy costs, as other elements such as cobalt, lead, and copper can also be detected at very low levels – making it easier for producers to avoid wasting even small amounts of valuable metals.” So, how does PFTNA technology provide this higher sensitivity so crucial for nickel mining, yet ensure much safer working conditions? “The answer to both questions lies in the neutrons. Unlike traditional radioactive isotopes found in other cross-belt analysers, PFTNA uses a deuterium-tritium neutron generator that can be switched on and off. This produces much higher-energy neutrons than those generated by radioactive isotopes, but drastically reduces the danger of radiation exposure and injury.”
The higher-energy neutrons it says make the CNA Pentos much more sensitive than its peers, enabling precise control of ores and raw material content. But another stage in production can also benefit from better process control: smelting in the electric arc furnace.
Another nickel operation, SLN Eramet in New Caledonia, uses a CNA Pentos instrument to control the basicity of the final slag. When basicity was increased from 0.58 to 0.61, and the FeO content from 5.0 to 12.5 wt%, viscosity decreased and the required smelting temperature dropped by 86°C – saving the plant a lot of energy over time.
Malvern Panalytical concludes: “In applications from the mine and stockpile to the kiln feed and electric arc furnace, better on-line process control can enable huge savings in energy use, waste, and costs. Not only can efficiency be maximised easily, but processes are made more sustainable thanks to the compounding effects of lower energy use and efficiency gains that add up rapidly. The mining industry today does not have the luxury of waiting until it’s completely ready to transform itself for a more sustainable future. The world needs metals now, and sustainability is an urgent priority. Fortunately, solutions like better on-line analysis are an easy and truly impactful step that can be taken immediately, resolving the dilemma of higher production bringing higher environmental impact.”
