NCC Roads A/S – Nyrand Grusgrav Quarry in Svebolle, Denmark, needed to improve its screening efficiency. Prior to screening, the aggregate goes through a traditional primary and secondary crushing process at a feed rate of 100 tph. Initial screening removes the +10 mm material which is recycled back into the crusher for further processing. The main feed material is then sent to a static double deck screening plant with a 5 mm top deck and 2 mm bottom deck. The final product is then sent to a washing plant. A further screening plant is also available to deal with any operational down time and when extra capacity is required.
Although the plant had been able to satisfy demand, the ‘blinding’ nature of the wire-mesh screening was ‘misplacing’ the material, reducing the amount that would become a saleable product, and leading to an overrun of fines.
The main problem however, was not blinding but that the wire mesh screens had to be replaced 10 times each yer due to breakages etc. This is a time intensive process and so resulted in operational down time. It also made the plant cost-inefficient due to the costs involved in having to change the wire screening media.
Following discussions with Sandvik during a site survey in the spring of 2014, NCC decided to focus on the existing wire mesh on the bottom deck of the double deck screen. After collecting data from the existing process, as well as setting targets for production, Sandvik proposed a solution involving WX7000 anti-blinding screening media. In addition to this technical solution, Sandvik also proposed providing a technical supervisor and training for the operators at the site. NCC accepted the Sandvik solution and replaced its wire mesh with Sandvik WX7000 at in beginning of 2015. The new anti-blinding screening media has now been effectively working for nearly a year, without the need for manual cleaning or replacement.
The WX7000 solution is a tensioned soft polyurethane screening media with dam bars and punched holes designed primarily for fine screening in difficult conditions. Its design solves blinding problems providing excellent screening efficiency in the final stage of screening. The wear life of the media is up to 10 times longer (or more in many applications) when compared with traditional wire mesh, thereby significantly lowering operating costs.
Dam bars slow down undersize material, enabling oversize material to pass more quickly resulting in more accurate screening and a better end product. Furthermore, and due to its unique properties, this polyurethane tensioned anti-blinding screening media needs minimal service maintenance which benefits operational safety and improves cost-per-t production.
A major difference, in comparison with other meshes or screen cloths, is that Sandvik’s WX7000 anti-blinding screening media keeps the apertures open in difficult conditions due to its flexibility ensuring high end product quality during its long lifetime. This is accomplished as there are no blind areas, or joints, in the length of the screen to which undersize particles can move without being screened out.
A larger efficient screen area also improves accuracy and increases capacity with the WX7000 screen cloths being of an especially hard wearing polyurethane design. This ensures a long working life, and minimizes the number of operational stoppages for screen cloth replacement (vitally, when a replacement has to be made, the process is fast and smooth).
These features have ensured that the Svebolle operation is more productive, more cost efficient and safer. The main 2 – 5 mm product is more competitive and ideal for concrete production.
Read the article online at: https://www.worldcement.com/europe-cis/11012017/sandvik-improves-efficiency-at-nyrand-grusgrav-quarry/