New state-of-the-art screening media is helping maximise screen uptime and longevity on minerals processing sites worldwide. Guy Woodford looks at some of the latest products.
When it came to improving the screening efficiency of
NCC Roads’ Nyrand Grusgrav quarry plays a vital role for the company producing 2-5mm aggregate for use in manufacturing asphalt and concrete. Annual production of this accurately sized material is in the region of 70,000 tonnes per annum, at an ideal hourly rate of 100tph, with the quarry operating a 5-day, 40-hour week.
Prior to screening, the aggregate goes through a traditional primary and secondary crushing process at a feed rate of 100tph. Initial screening removes the +10mm 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 5mm top deck and 2mm bottom deck. The final product is then sent to a washing plant. A further screening plant is also available to deal with any operational downtime and when extra capacity is required.
Although the plant has been able to satisfy demand, the screening process has not been without problems. The ‘blinding’ nature of the wire-mesh screening media has resulted in material being ‘misplaced’, thereby reducing the amount of material that becomes a saleable product, and leading to an overrun of fines.
Blinding, however, was not the main problem: the wire mesh screens had to be replaced 10 times each year due to breakages etc. This resulted in operational downtime, with replacing the screening media being a time intensive process. What was more, this was making the entire plant cost-inefficient due to the costs involved in having to change the wire screening media. Many man hours were being used in this often dangerous undertaking, as well as the plant losing a great deal of production.
Following discussions between NCC and Sandvik during a site survey in the spring of 2014, it was decided as one of the action points, to focus on the existing wire mesh on the bottom deck of the double deck screen. This was due to the problems that were being experienced with both media lifetime and blinding.
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 the 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-tonne 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 minimises the number of operational stoppages for screen cloth replacement (vitally, when a replacement has to be made, the process is fast and smooth).
All of these features have ensured that the Svebölle operation is now a more productive, more cost-efficient and safer work place. The main 2-5mm product is produced more efficiently, with fines in the final product being reduced from 6% - 3%. This improved product quality has made NCC’s products more competitive, and ideal for concrete production, amongst other applications.
The hard-wearing nature of the WX7000 polyurethane screens has resulted in safer handling and increased production capacity. This is due to the elimination of manual cleaning and screen media lifetime being extended by more than 10 times compared to the previous wire mesh. The resulting more efficient operation has reduced the cost of production providing NCC Svebölle management with greater peace of mind and confidence in their production capabilities.
The new software from Metso, the Finnish crushing and screening equipment manufacturing giant, makes it easier than ever to design a modular screening media layout for a screen deck and follow the wear rate. It offers full control of your screens and the media, and enables professional follow-up of screen performance as well as the tracking of change-outs. This makes keeping track of the actual cost-per-tonne easy.
After a new screen deck is configured in Metso Screen Planner, its behaviour and wear can be monitored. This data will help assess the performance of the media and foresee the need for new modules.
The software is something unique to Metso. It is a web-based cloud solution, meaning that it can easily be accessed anywhere, on any device, as long as an internet connection is available.
Haver & Boecker, a leading equipment manufacturer and solutions provider in aggregates and mining applications, offers its Tyler brand of hooked engineered screen media as a solution to the problem of expensive deck conversions. Tensioned screen media can be used on a cambered deck, eliminating the need for a deck conversion when switching from woven wire to polyurethane screen media. The media includes products such as Ty-Max and Ty-Wire.
Hooked screen media allows operations to easily switch from woven wire to modular polyurethane products without the expense of a deck conversion. Retrofitting a machine from a cambered deck to a flat deck can cost as much as $15,000 per deck. Tyler’s tensioned screen media is used on a cambered deck to eliminate the need for that conversion. This also allows operators to test the media on a vibrating screen with no additional cost or commitment.
Another benefit is that Ty-Max and Ty-Wire can be blended with woven wire or self-cleaning screens on cambered decks. In many applications, operators are looking for more wear life on the feed end of the screen. This can be accomplished by installing a section of Ty-Max at the feed end. Ty-Wire can be used in the middle of the deck, for example, where basic screening takes place to give operators the ideal combination of wear life and open area. Using woven wire or self-cleaning screens at the discharge end will provide maximum open area at the end of the deck.
The polyurethane screen media is manufactured out of Tyrethane, Haver & Boecker’s signature blend of polyurethane. It’s made in the only facility in North America that blends its own material, which is critical for quality control. Chemists developed Tyrethane to offer the best combination of open area and wear life for both wet and dry applications. Tyrethane is poured open cast, resulting in 1.5 to 2 times longer wear life than injection-moulded products sold at comparable prices. In addition, open cast polyurethane permanently hardens when cured to maintain its chemical properties, so it resists wear and tear. Injection-moulded screens can soften when the temperature rises during screening, resulting in shorter wear life.
Haver & Boecker manufactures a variety of Tyrethane screen media options to suit different operations’ applications, taking into consideration top sizes and opening requirements. Operators looking for high durability and strength choose Ty-Max, which
Haver & Boecker also offers Ty-Deck modular panels, available in multiple configurations for flat deck setups. Ty-Deck’s lightweight design eases installation and sectional deck replacements.
Blue Group has signed an exclusive distribution agreement with
Major Wire’s innovations include the Flex-Mat, a high vibration wire screen media said to have increased efficiency in more than 35,000 applications across the world. The secret behind this performance are the individual wires, which are able to vibrate independently. These individual wires which are held in place by distinctive green polyurethane strips, vibrate between 6,000 and 10,000 cycles/minute, said to be up to 13 times more than a standard screenbox. This is said by Major Wire to improve material stratification, the process by which vibration in a bed of material causes the larger particles to rise to the top and smaller particles to fall to the bottom, thus allowing the specified sizes to fall through the wire, as opposed to being carried forward with the larger sized material. In addition to claimed improved productivity and separation, the Flex-Mat improves open area, helps to eliminate any blinding and pegging, as well as increasing the wear life of the screen.
OptimumWire is said by Major Wire to be another industry first. With its high carbon, manganese metallurgical content the wire is said to last up to 40% longer, which in turn decreases labour and downtime costs. Furthermore, each screen is manufactured with extremely tight crimps and weave, as well as a leading stringent wire opening.
The screen media manufactured by Major Wire are available in a number of different designs and configurations, allowing work in a variety of applications: the Double-Wire, which provides precise sorting in high impact and heavy material applications, the ‘D series’ for precise passing and the ‘S Series’ which removes fines and produces a cleaner retaining material whilst reducing the binding of sticky, wet materials. The media also allows for installation into the screening equipment of all major brands.
Commenting on the agreement with
Major Wire will be distributed via Blue Group’s Spares Facility with popular styles and sizes being held in stock for immediate despatch.
