Coal Age

OCT-NOV 2017

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October/November 2017 www.coalage.com 41 operating ideas continued Optimizing Fine Coal Circuits FLSmidth is providing an ongoing design and operational guidance to increase fine coal output and productivity improve- ments at one of New South Wales' premier open-pit coal mines. A site survey as part of the program identified the problems im- pacting production and total output. From that survey two goals were identified. The long-term goal is optimized performance and productivity throughout the coal han- dling and preparation plant (CHPP). Along the way, a medium-term goal is to make the installed equipment fit for purpose and im- prove equipment efficiencies and reliability. Initial stages have focused on optimiz- ing the performance of the reflux classifier and the capabilities of the thickener, which is also being upgraded to meet current and future production targets. With certain feeds, the thickener cannot process the re- fuse stream at the required rate, which has meant contaminated process water, result- ing in blockages in the clarified water lines and clogged valves, strainers and nozzles. A critical contributing factor is the refuse underflow now being treated by fil- ters for dewatering rather than the initial design where refuse was diverted straight to a tailings dam. With the high proportion of slimes in the clarified water circuit, the circuit was frequently blocking, requiring correspond- ing unscheduled maintenance to unclog the valves — and leading to substantial losses in production time and productivity. Optimizing the reflux classifier circuit was undertaken as a number of incremen- tal steps and achieved improvements in availability and reliability. The first phase involved reviewing and assessing the fluidizing water circuit and impacts on the fine coal circuit and equip- ment operations. Phase two involved re- viewing the density control and calibra- tion, adjustments to the PLC code and replacement of the density probes. The re- sult of these steps is reliable and accurate density control with minimal operator ad- justment is required. The third phase was to improve the mechanical reliability of the reflux classifier. As part of that process, the dart valve was upgraded to a two-arm assembly with shrouds, a change that has improved reli- ability of the valve's operation and mini- mal splashing. Reports from the mine indicate the investment in the program is paying off. Individually most of the improvements have been nominal, but, combined, are now delivering results with 3%-5% in- creases in output from the fine coal cir- cuit regularly achievable. The fine coal circuit is now achieving target production requirements and is ex- pected to meet future production targets. Circuit maintenance is now on a scheduled basis. Water quality to the circuit has im- proved and work is ongoing in this area. With the success of this first stage, the mine has planned for additional similar investigations, looking to achieve simi- lar improvements in processing circuits across the site. Optimizing the fine coal circuit solved problems with the thickener and water use internally. Suspended Magnets • Metal Detectors Heavy Duty Feeders Double-Team Dangerous Tramp Metals! Download Catalogs & Product Selection Guides Suspended Magnets • Metal Detectors Heavy Duty Feeders Eriez' Suspended Magnets and Metal Detectors remove tramp metals before they reach your valuable crushers and downstream equipment. 888-300-3743 • www.eriez.com Download Catalogs & Product Selection Guides

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