Coal Age

APR 2019

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April 2019 29 sampling systems continued same components that are of interest to coal miners. "The client wants to know carbon content, the sulfur and sulfide content," Petra Muehlen, head of sales, SpectraFlow Analytics Ltd., said. "These are things we can analyze very well." The conveyor is enclosed due to the fine grind of the ore. The miner initially trialed one airslide NIR ana- lyzer model and then adopted a sec- ond. "They were very happy with the results," Muehlen said. The mine is one of 45 sites world- wide, to include iron ore and bauxite ops, that have installed SpectraFlow's NIR analyzers, which can be config- ured for either crossbelt or airslide applications. The solution offers a range of ben- efits, including low cost of ownership and easy maintenance, the company reported. For the crossbelt model, the annual estimated cost in consumables is roughly $1,000. It requires five min- utes of maintenance per week and 15 additional minutes every other month. It has an aluminum frame, weighs roughly 350 lb and offers 98% online availability, the company reported. Muehlen said the main draws are accuracy and ease of use. "It can provide a full and direct analysis of coal: the carbon, the mois- ture, ash, sulfur and sulfide," she said. And it does it without leveraging radio- active materials and all the steps and requirements that come with them. The analyzer has two main com- ponents, a light source and a detector. Two bulbs illuminate the materi- als on the moving belt beneath it. "We use halogen lightbulbs," Muehlen said. "We look at the near-infrared wavelength range, a wavelength that is not visible to our eyes." A Fourier transform infrared spec- trometer continuously scans the sur- face of the material and measures ab- sorption rates. The system does 150 analyses per minute. The numbers generated by the scans are averaged, and the result is returned to the con- trol software, the company reported. The software provides values for all the coal-relevant components, Muehlen said. "We can then calculate the calorific value," she said. "We can do a detailed analysis on the ash, and not just total ash, but we can give you the calcium, iron, aluminum, etc." Providing a direct analysis distin- guishes the solution, Muehlen said. "All other analyzer technologies have a lim- ited range of elements they can detect or analyze," she said, "and they need to either use additional analyzers, for example to analyze moisture, or they must calculate the remaining constitu- ents of interest, for example carbon." Built into those back-calculations are variables that can increase the margin of error. "You have the belt scale, which has an error, a moisture meter, which has an error, and your ac- tual analysis has a certain error," Mue- hlen said. "The errors just all add up." SpectraFlow's NIR analyzer "di- rectly measures and analyzes all of these constituents: the organic, min- eral and moisture content," Muehlen said. "That just makes it more accu- rate and applicable." The results are not affected by the speed of the belt or the depth of the material. However, the solution works best on materials that are mixed and relatively uniform. "We perform a surface analysis," Muehlen said. "The limitation is we cannot handle lay- ered materials." A crossbelt unit is ideally placed to scan coal coming directly out of the crusher, she said, or after it has been through a couple of transfer points ensuring the material is well-blend- ed. Another suitable location is over the belt carrying coal already mixed and ready for shipment. A power plant could deploy it to the belt that feeds a silo. The technology was originally developed in 2006 and 2007 by ABB. "SpectraFlow effected a management buyout from ABB in 2013," she said. "Since then, as an independent com- pany, we kept on further developing and specializing that type of online analyzer technology." The company supplies the com- plete online NIR analyzer. For the crossbelt model, the client provides a frame, a couple kilowatts of power, and the data communications hook- up. "We supply software for the stock- pile management," Muehlen said. Those software packages include On- line Control, FLS QCX, ABB RMP, and KIMAE. SpectraFlow does the installa- tion, calibration and commissioning." SpectraFlow's over-the-belt NIR analyzer, above, offers 98% online availability, the company reports. (Photo: SpectraFlow)

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