The DU64 for extremely difficult-to-screen materials.

For the best part of a decade ThyssenKrupp Fördertechniktook has been manufacturing the world''s largest screening machines for specialist applications.

ThyssenKrupp is now launching the DU 64-3.6 x 8.0 (8.9) ED, the latest generation screen designed for extremely difficult-to-screen materials.

The screen deck has two steps causing the material bed to break up, enabling the fines to be screened more quickly and the screen efficiency is considerably increased compared to traditional screens. The feed capacity of these state-of-the-art machines is 6,000 - 8,000 t/h of oil sand with a bitumen content of 18% and a feed size of 0-600/900 mm.

This material bed is broken up by six ThyssenKrupp size IV exciters, each generating a centrifugal force of 56 t. A 200 kW motor drives two rows of size IV exciters - three in each row - through a synchronised gear box reducer.

Synchronisation of the two exciter rows allows the amplitude between the feed and the discharge side to be adjusted enabling a higher conveying speed and break up of the material bed in the feed area if required.

To respond to changing material characteristics a frequency converter is provided which ensures that the required operating speed and a constantly good screening efficiency are attained.

In order to meet the stringent quality requirements for materials, welding technology and machining, the screens have been and still are manufactured in Germany only. Normally, the screens are installed in steel structure buildings - in this case at a height of 20m. They incorporate isolation frames to minimize the dynamic foundation loads passed to the supporting structure of the screen.

Design calculations were carried out with the aid of finite element analysis. Since the latest generation has proved its readiness for series production, comprehensive vibration and strain measurements are being performed on a routine basis during the test run at the workshop for verification of the design calculations.