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Clear Edge Filtration (formally Madison Filtration) approached Boss Polymer Technologies to be an alternative supplier of a rubber extrusion that was sewn to the edge of the rotary vacuum drum (RVD) belt discharge systems which they produce.

Clear Edge Filtration is a global leader in the manufacture and supply of industrial filtration products and filter media to organisations responsible for filtering liquids from solids, dewatering, collecting and filtering dust, air filtration, filtering and purifying hot gases, and other industrial process applications.

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Key Facts



Clear Edge Filtration approached Boss Polymer Technologies to be an alternative supplier of a rubber extrusion



Since commencement Boss Polymer has supplied 1.5 million metres of co-extruded polymer filtration cloth



Due to its innovative design one customer experienced a 3.5 tonne per day increase in productivity using NuTrak

Composite Extrusion Solution

Clear Edge approached Boss for a rubber extrusion for the edge of their belts. Clear Edge weaves and processes special cloth that is used in the mineral extraction industry.

In the past some of the cloth products required rubber extractions onto either side of the belt to act as guides and to help tension the cloth belts when they are installed on the mineral extraction machinery. Traditional issues include the product not running true, catching, buckling, tearing, causing a shortened life span, additionally, rubber would stretch and catch in the guide wheels.

Clear Edge approached Boss and explained their issues. Managing Director, Norm Mills developed an idea that would solve the problems being experienced. Clear Edge were immediately interested, not realising that Boss had the ability to take a narrow section of their cloth and extrude a specialty polymer onto the narrow section of the belt and fusion weld it to the cloth during the extrusion process, creating a composite extrusion.

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Benefits Were Numerous and Significant

There was an option to either sew or hot-air weld, depending on the cloth used. The design enabled Clear Edge to easily sew cloth to cloth, rather than rubber to cloth. The benefits were numerous and significant, less jamming and wear of cloth, the process was much easier on the machinery, rubber tears were avoided. And using the co-extruded polymer elastic cloth made it much easier to create tension. Resulting in the cloth coming out straight and taut. The 18 metre length wraps around on itself and is joined to create an endless belt.

Further to this, an innovative new knuckle joining system was developed. After the belts are cut to size, the fixing knuckles are joined to the edge cloth system and the finished belt is sent to the Aluminium refineries.

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Developing a New Method

Following the success of Edge Trak®, the engineers at Clear Edge approached Boss to develop a new method for attaching filter media to disk, drum and pan filters.

Traditional methods were time-consuming, difficult and required skilled labour. One had to be careful not to damage the cloth, repetitive strain injuries were a concern and the product could be very hard upon removal as crystals would form inside the rope causing it to become rock hard. The same idea was extended to the frame track, with the proposal to jam the rubber into the groove. In collaboration with Boss M.D, Norm Mills and their engineers the idea of an undercut and locking key was conceived.

This method replaces the traditional caulking method or the more modern bolt down clamping methods on disk and pan filters and makes the bag method for disk filters obsolete. Its main function is to eliminate the numerous Operational Health & Safety issues associated with the existing methods of re-clothing filters. The filter cloth can be secured to a filter without the use of power tools, it is a simple operation to both install and remove individual cloths. The major advantage for disc filters is that the cloth can be exchanged without removing the heavy segments from the filter. On a drum filter, the cloth exchange time can be remarkably shortened by changing the required cells.

Proven to be Highly Effective

Mr Robert Bell stated that NuTrak has been proven to be highly effective 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.”

Mr Bell also stated that “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.