A highly cost effective investment: Sandvik’s new screening media system

The material in the bottom hand has been screened with the previous screening media, whilst the uppermost material has been screened using the Sandvik WR modular system

A focus on quality
With around 25% of the Danish market, Nymølle Stenindustrier AS is one of Denmark's largest suppliers of gravel. The company, which started operation in 1909, now has 30 facilities in Fyn, Jutland and Själland, with a combined annual production 7-8 million tonnes of sand and aggregate, with the materials being used for concrete structures, asphalt, road building, drains and other associated purposes. With its own laboratory facility Nymølle Stenindustrier AS is able to analyse and check the materials produced thus ensuring that customers receive high quality end products. Their intense focus on quality has made them very receptive to any solutions that can improve screening production and operational efficiency.

The Nymølle Stenindustrier AS facility at Røde Kro is located near Aabenrå in Jutland, producing approximately 250,000 tonnes of material each year, of which 110,000 tonnes are washed sand, with the remainder being aggregate. During the summer of 2011 the facility identified a requirement to replace the screening media in one of the primary screens – a Svedala VFS 48/21 - which also operates as a washing screen. In order to facilitate a replacement, the sites Production Manager, Jens Rasmussen, contacted Sandvik Construction, which had just launched its new patent-protected system, WR Modular Screening Media. "We wanted to reduce the proportion of undersize particles further, and were open to try a new solution. Immediately after the Sandvik WR Modular Screening Media had been installed the improvement was considerable, and, additionally, the production capacity of the screen increased - which was a real bonus." Says Jens Rasmussen.
The production manager Jens Rasmussen at Nymølle Stenindustrier AS is showing a Sandvik WR module

The production manager Jens Rasmussen at Nymølle Stenindustrier AS is showing a Sandvik WR module

The solution: Sandvik WR Modular Screening Media
A major difference, in comparison with other modular systems on the market, is that the Sandvik WR Modular Screening Media has a larger open area, with this area being extended across the entire width of the screen. Of this feature, Elna Hovén, Product Manager Screening Media, Sandvik Construction, says – "There are no blind areas, or joints, in the length of the screen to which undersize particles can move without being screened out. This larger screen area improves accuracy and increases capacity." An additional benefit derived from the system is that the screen cloths are mounted crosswise across the screen instead of along it, with the flexible modules creating an efficient cascade effect when the rock material is transported forwards. The "billowing" movement hastens stratification, ensuring any undersize particles are more rapidly screened out.

The screen cloths used in the Sandvik WR system are of an especially hardwearing design, with this being due to a newly developed thin, fibre-reinforced rubber screen membrane for dry screening, or polyurethane for wet screening. This ensures a long working life, and minimises the number of operational stoppages for screen cloth replacement (vitally, when a replacement has to be made, the process is fast and smooth). Efficiency is further enhanced as the adapter system utilised lasts for several screen replacements, with an inbuilt protective flap combined with protective rubber capping.

With the above design features inherent to the Sandvik WR system, replacing the screen system at Røde Kro proved to be easy, with neither the frame nor the screen needing to be rebuilt. The existing polyurethane screens were quickly removed and a new adapter system installed, with the only work taking a relatively substantial time being the removal of the old screen modules which had become rusted in after many years of operation.

A major reason for ease of installation and efficient operation of the WR system is that the newly installed Sandvik adapter creates transverse tracks into which the screen cloths are placed and locked with a rubber wedge, resulting in no requirement for bolts, special tools or welding. Of the fast and easy installation and replacement of screen cloth Jens Rasmussen says: "The screen cloths will be easy to replace, and we are very pleased that the screen did not have to be rebuilt. Plus the modular system fits all machine types." Further highlighting the flexibility of the Sandvik system, when the time eventually comes for worn-out screen cloths to be replaced, the wedge is simply released with one easy operation.

Cost-effective investment
After the change over to the Sandvik WR Modular Screening Media, Jens Rasmussen noted considerable improvements. The proportion of undersize particles, which had been 23%, had now reduced to only 9%, and Jens was also delighted to note improved capacity of 350tph; a 15% improvement on the 300tph the old screen modules had been capable of. Of the new screening system Jens concludes: "The combination of the large, open screening area and cascade effect is enormously efficient. It provides greater capacity through the screen and we get sharper (material) separation. We are now able to deliver an even higher quality to our customers: Sandvik Construction's new system is proving to be a highly cost-effective investment."

For further information please contact:

Satu Rämö
Global Marketing Communication Manager
Sandvik Construction
Office Phone: +358 205 44 151
Mobile Phone: +358 40 537 4020
E-mail: satu.ramo@sandvik.com