Coal Tailings Dewatering Using Modern Membrane Filter Presses —First Eperience in Australia

摘要

Water shortage as well as significant regulatory and environmental pressure are pushing the Australian coal industry to look at new solutions for fine coal tailings dewatering. While most fine coal tailings are disposed off in tailings dams, further tailings dewatering in Australia is commonly limited to belt press filters after thickening. Relatively low pressure belt presses are not always able to produce a solid cake and have high flocculant consumption. Both is particular the case for difficult to dewater tailings containing high amounts of clays. Only high pressure filters, in particular membrane chamber filter presses, are able to produce solid cakes from high montmorillonite clay. Those presses feed and filter the slurry into the chamber at pressure up to 8 bar and further dewater the formed cake by membrane squeezing up to 15 bar. This high dewatering pressure enables the production of solid and easily handable cakes even for very fine feed slurries such as clays. Pressure filtration technology has moved a long way from the old days of plate and frame filters, with a new breed of membrane chamber filter presses, providing a new level of performance, automation, improved maintenance and reduced operating costs, making increased tonnes at lower moistures a reality. The totally automatic operation and modular design'of the Andritz / Netzsch presses allows them to be used efficient in today's CPP. This presentation will cover the proven benefits of Andritz membrane filter presses-in Australia represented by Jord International-and their use in fine tailings dewatering. Dartbrook Coal's Australian industry first tailings dewatering facility utilizing Andritz membrane chamber filter presses is proving the technology can perform on the most demanding of high clay tailings product, delivering a handle able product were traditional technologies have failed. Various crucial factors for a successful filter press operation in a tailings applications come down to filter designs. However, the filter press design is drastically dependent on the filter feed characteristics so that there is not "one" coal tailings filter press design. This will be demonstrated by a comparison of design solutions for different coal tailings. The presentation discusses design and operation of filter presses for coal tailings applications to suit both, good filtering and worst case clay tailings. Details on pilot-plant and full scale operation experiences at Anglo Coal's Dartbrook CHPP and a comparison to further pilot plant trials undertaken will be presented. An outlook into filter presses for flotation concentrate dewatering will also be given as this technology is used overseas for coal flotation concentrate dewatering.