Big increase in productivity
The Eschenbach Municpal Gravel Works LU works with modular strainer baskets made of elastic materials supplied by REMA TIP TOP Vulc-Material AG/Switzerland. Here downstream of the washing drum, a circular sizer is used for primary classification of the processed bulk solids (Fig. 1). With wall gravel in the size 0-100 mm as feed material and annual feed rates of 80 000 to 90 000 m³, the lifetime of the two steel strainer baskets was limited to an average of one year. The inner basket made of steel plate, with a diameter of 1 550 mm, length of 2 300 mm, mesh width of 50 mm² and a web width of 10 mm, was exposed to severe wear. The outer basket made of steel plate, with a diameter of 2 550 mm, length of 1 770 mm, mesh width of 8 mm² and a web width of 5 mm was also subject to heavy wear.
The two baskets were redesigned with regard to their wear protection. The polygon was rearranged so that the basket modules effect an overthrow of the bulk solids. This results in better screening efficiency and a substantial reduction in wear. Criteria for the performance and wear improvement are length, width, thickness, shape of the perforations, size of the perforations, blind zones and of course the material quality of the elastic screen panels. With this system adjustments to meet changing requirements, apart from special cases, are possible. The improved inner basket has a larger diameter of 1 800 mm and is arranged with 2 x 16 screen modules as a polygon. The dimensions of the elastic screen modules measure 1150 x 347 mm at a thickness of 23 or 18 mm respectively. At both the feed and discharge there is a blind zone. The optimized outer basket has an increased diameter of 1 950 mm. 44 elastic modules measuring 358 x 1975 mm, with a thickness of 6 mm, are also arranged as a polygon (Fig. 2).
The new solution has the following advantages:
• Rapid and easy installation of the modular, elastic screening surfaces
• Partially exchangeable units that are easy to handle
• Low-cost installation and procurement of replacement parts
• Polygonal arrangement of the screen modules for optimum circulation of the feed material and increased throughput rate
• Reduction in noise emissions
• Trouble-free and individual fitting of the modular system for every sector diameter and every drum length
• Convincing self-cleaning of the elastic screen modules
• Overall system responsibility with consultation, design and engineering of the drum body, the screen modules and installation from one source.
After the first year of operation at Eschenbach Gravel Works, no wear of the elastic screen modules could be detected. A positive aspect noticed by the operators was the reduced noise, and there was no unscheduled downtime for repairs. The screen modules did not need any replacement during that time and the gravel works was able to register a cost saving overall.
REMA TIP TOP Vulc-Material AG, Urdorf-Zürich (CH), Tel.: +44 735-82-00, www.rema-tiptop.de , info@rema-tiptop.ch
