Innovative refining filters boost productivity

quality-iso-9001-pms302An Australian designed range of innovative, high performance filtration fabric products for rotary vacuum drum, disc and pan filters is delivering significant productivity increases for international refining companies in the alumina, coal and other mineral industries.

The Madison Filter NuTrak™ and FrameTrak™ products use innovative fixing systems to fit the filtration fabric to the refining equipment. The patented technology, developed in Melbourne by Madison Filter in collaboration with Boss Polymer Technologies, increases yields, reduces down time and reduces environmental, occupational health and safety risks.

Madison Filter Technical Manager Robert Bell said Boss Polymer Technologies was an engineering partner in developing this new technology for the filtration fabric panels used in mineral processing. “A major alumina refining customer was battling problems traditionally faced with rotary vacuum drum (RVD) belt discharge systems. The old style, fully sewn belts suffered abrasive wear at the drum edges, ripple lines formed, high spots were created and complex guidance systems were required. These issues resulted in rapid belt wear and lack of suction on the drum, which reduced the effectiveness of the filter. We asked Boss for some ideas and their input was critical to the project’s success,” he said.

Engineering solution for RVDs

The key to these state of the art filter systems is the extruded composite elastomer and fabric edge track co-designed and manufactured by Boss Polymer Technologies. Boss Managing Director Norman Mills said: “We originally saw opportunities to improve the filter fixing system. This change led to improving the overall filter performance and streamlining the filter fitting and removal process on RVDs.

“A tough, flexible, chemical resistant elastomer formula enabled the solution. In a single step, we extrude an elastomer edge track profile on to a piece of Madison Filter high performance fabric. The fabric part of this composite component is then welded to the large sheet of filter fabric already cut to size by Madison Filter. Our extrusion process eliminates time consuming sewing of these components. The easy to handle, flexible polymer edge then slots into a simple guidance system fitted to the drum.

“During a site visit to an alumina refinery in Western Australia, we co-conceived a simple system to on site join the two ends of the belt using moulded castellated knuckles and locking pins. The Boss co-designed and supplied moulded castellated knuckles are welded to the ends of the composite edge track at Madison Filter as part of the final assembly of the filter belt. Boss was also asked to design and manufacture the specialised machines now used in Australia and the United States to weld the knuckles to the belt,” said Norman Mills.

The result is a filter that sits flat and tight on the RVD to maximise vacuum, and to create a secure belt discharge membrane to increase filtering performance. Replacement is usually done by connecting the new belt to the old belt and running the machine to pull the new belt around the drum.

The Madison Filter product for RVD belt discharge systems is NuTrak™. “This product is now proven on customer equipment in large Australian alumina and coal refining operations. We are gaining a 16 to 20% increase in vacuum compared to traditional edge tracks. This results in a thicker filter cake with cake dryness increased by up to 10%. The additional belt width provided is up to 120mm, allowing up to 2 square metres more filtration area. These benefits are delivering customers greater productivity, ranging up to an extra 0.6 tonne of product per hour,” said Robert Bell.

“Because NuTrak™ tracks better, there is reduced reliance on the tracking system and belt travel is greatly improved. The alumina industry is an early adopter of cutting edge technology, and one customer using this system has cut filter replacement time from eight hours to 40 minutes using two men, rather than three. That benefit, plus the longer life of the belt itself, translates to a 3.5 tonne per day increase in productivity for that customer,” said Robert Bell.

Extending the technology

For drum, disc and pan filters, Madison Filter and Boss Polymer Technologies developed FrameTrak™, which applies similar technology. In this case, the special steel fixing track is fitted to the frames of the drum, disc or pan filter. The composite elastomer profiles are slotted in to this track and held in place with a second composite elastomer locking strip to eliminate leaks. In addition to the elastomer/fabric edge track, Boss custom joins the corners required to make up these large filter sheets.

The FrameTrakTM system was developed in tandem with international equipment supplier BOKELA Gmbh in Germany, which enabled comprehensive product testing in real life situations.

Environment and OH+S benefits

“While this technology offers mineral processors significant productivity improvements and cost savings, perhaps the major advantage of the NuTrakTM and FrameTrakTM systems is their improved environmental performance and reduced occupational health and safety risks,” said Robert Bell.

“These filters are easily removed and installed, and caulking grooves and ropes, nuts, bolts and silicone are eliminated by the composite elastomer edge profile. No power tools, hammers, chisels or excessive force is required to fit or remove the filter cloth, because it simply slots into the fixing track. The need for wash downs with caustic or other chemicals is greatly reduced, providing a much more environmentally friendly processing system,” he said.

Custom filter systems

NuTrakTM and FrameTrakTM filters can be custom made to fit virtually any mineral refining equipment and Madison Filter has technical support teams based strategically for quick access to Australia’s major mineral processing centres. Boss manufactures and supplies a wide range of polymer products engineered for the mining and refining industries, including extruded vibration screen capping rubbers, dust cloth grip strip, moulded wear/impact plates, and linings manufactured from rubber, rubber metal and HDPE. Boss also supplies a wide range of high quality sheet rubber products, dust cloths, and HDPE sheet and board.