Quarries today face pressures from every angle, eg significant demand fluctuation, OHS obligations, ongoing maintenance and cost down targets, and maximising final product mix. Screening media is a low cost portion of this mix but has a significant impact on the final product. There are many technical details involved in specifying the correct screen type given the process, equipment and final product mix.
For example, there are numerous screening media options suited to sand quarries, depending on the site specifications, source material, the equipment and process chosen and the customer?s product demands.
Screening of fine sands is split into either ?dry? or ?wet? screening. ?Dry? screening utilises traditional wire screens, either woven wire and/or piano wire, depending on the quarry?s location and site-specific requirements. Given these plants are usually dealing with small to medium volumes, mobile screening units are often the best solution, allowing the site to move the screening equipment to the product.
In a two-deck mobile screen set-up, the top deck may be designed for the scalping process, and utilise a 25mm aperture, 6.3 diameter high tensile woven wire mesh screen. The top deck is often called ?the protection deck? as it can maximise the life of the deck below by taking away unnecessary larger pieces, ie rocks and organics. The bottom deck may then be set up for sizing, and be running a 5mm aperture 1.25mm diameter piano wire screen, manufactured in high tensile or stainless steel wire. Stainless steel is often used when moisture starts to build up in the initial product or if the site has clay issues and needs to cut through the mix. Knowing which screening media to choose is only part of the challenge; understanding how it fits to the screen deck is crucial in maximising its life, reducing downtime and maintenance requirements. Locker Group has built this understanding into its recently released mobile screening database.
Alternatively, ?wet? screening is often run on fixed screening plant, where the material is moved to one location on-site for screening. ?Wet? screening occurs in larger sites where the throughput volume justifies non-metallic screening media, which offers longer wear life. Even within non-metallic screening media, choice reigns supreme with rubber and polyurethane cross-tension screens and poly modular screening products available. A ?wet? screening set-up may involve a rubber cross-tension scalping screen, followed by either poly cross-tension or poly modular wash screens, then a poly cross-tension or poly modular dewatering screen!
These screening options are tailored to the particular nature of screening sand. In addition, other screen types and set-ups are suited to aggregate, lime and others. Then, to add to these choices, there are additional requirements, when it comes to hook type and orientation, and fixing methods for each particular screen and machine combination.
There is no doubt that the life of a quarry manager is busy and complicated enough, without wanting to understand and recall, at a moment?s notice, the intricacies and details of every screen. Hence, suppliers such as Locker Group are working extremely hard to simplify this process.
At CMIC 10 in Queensland in October, Locker Group officially launched its mobile screening database, which incorporates the screen requirements of the most popular mobile screening plant currently available in Australia. During the conference, Locker Group challenged delegates to name a mobile screening unit (manufacturer and model) that was not in the database.
Locker Group claims that if you need to replace a screen, you can contact it with the name and model number and its customer representatives will quote you on the suitable screen, including hook profile and fixing methods, based on the OEM specifications. In addition, if your mobile screen has been modified, or you are running fixed plant, Locker Group can measure to suit and still retain the details on file. In future, all you would need to do is make a phone call.
Source: The Locker Group