Engineering & Mining Journal

JAN 2019

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Page 51 of 59

50 E&MJ • JANUARY 2019 PROCESSING SOLUTIONS Crossbelt online elemental analyzers provide a means for reliable online analysis of bulk raw materials processed at mining opera- tions. Minute-by-minute online analysis of ores, concentrates and various raw materi- als allows accurate, high frequency process control to reduce process upsets, increase throughput and maintain quality. However, the nature of moving, processing and ana- lyzing bulk materials at mine sites presents a harsh environment for the equipment. Under such conditions, it makes sense to perform regular checks and maintenance to the system, to ensure it is performing most effi ciently as well as to keep in com- pliance with the manufacturer's warranty. A recent blog post by ThermoFisher Scien- tifi c's Darell Leetham offers a list of four recommended maintenance tasks that will help to keep a crossbelt online analyzer at optimal performance: • Weekly Maintenance – Check heat exchanger on electronics unit. – Clean electronics unit exterior. – Check excess material and belt mis- alignment switches. Check the shield blocks and shield assembly for dam- age. Check the electronics unit enclo- sure temperature. • Monthly Maintenance – Check that the belt scale and tacho- meter (if applicable) are working pro- perly. Check slider bed for wear. • Six-month Maintenance – Perform a source leak test (isotope- based systems). – Measure reference standards, record data and compare to documented val- ues and prior measurements. • Two-year Maintenance – Replenish neutron sources (isotope- based analyzers). Laser Ablation Applications in Elemental Analysis It sounds suspiciously like a potentially painful medical procedure, and actually is used in a number of treatments rang- ing from varicose vein therapy to fi ghting cancer. However, laser ablation is a useful microanalytic tool for metallurgical analy- sis and earth sciences studies. The concept is not new; it's been around for many years, but as a 2016 paper 1 points out, signifi cant advances have taken place in laser ablation inductively-coupled plas- ma mass spectrometry (LA-ICP-MS) – the technology's formal name – over the past two decades. Instruments have become widely available in laboratories worldwide and the number of applications in earth science has been greatly expanded by ongo- ing technological development, particularly with respect to analysis speed, resolution and sensitivity, and by the availability of reliable reference materials designed for specifi c purposes. The LA-ICP-MS method, according to the authors, is cost-effective compared to other techniques, such as sec- ondary ion mass spectrometry (SIMS). For these reasons, LA-ICP-MS has established itself as the method of choice for genera- tion of multi-element datasets for specifi c minerals. Applications have expanded from trace element 'spot' analysis to mapping of areas within a sample, greatly assisted by the widespread availability of software. Another paper, presented at the 2017 North American Workshop on Laser Ablation hosted by the Jackson School of Geoscienc- es at the University of Texas at Austin, of- fered a glimpse of how the method is being used in mineral processing applications. The presentation 2 noted that LA-ICP-MS offers a unique facet to process mineralogy and pointed out that many economic metals are present at ultra-low levels in mineral depos- its and require complex recovery techniques to separate them from the bulk ore. Under- standing metal occurrence is necessary for implementing the proper recovery strategies. According to the authors, LA-ICP-MS is a cost-effective and versatile method for mea- suring precious-metals and other economic trace-elements in solid solution in various types of mineral phases while achieving low detection limits. The results can help calculate accurate plant metal-balances, di- agnose reasons for lower than expected re- coveries in a concentrator, or when includ- Keeping Crossbelt Analyzers in Top Operating Condition Regularly scheduled maintenance checks and tests are key factors in ensuring accurate measurement information. 1 Trace Element Analysis of Minerals in Magmatic-Hy- drothermal Ores by Laser Ablation Inductively-Coupled Plasma Mass Spectrometry: Approaches and Opportu- nities, N. Cook, C. Ciobanu, L. George, Z-Y Zhu, B. Wade and K. Ehrig. Minerals 2016, Vol. 6, Issue 4. 2 Application of LA-ICP-MS Analysis to Process Mineral- ogy: Ga and Ge Recovery at Kipushi Deposit, M. Kelvin, J. Petrus, M. Leybourne and V.i Nkuna.

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