Modern Quarrying Q3 2019

As standard, the ST2.8 can oper- ate as a 2-way or 3-way split (you can either take out three stockpiles or combine the mid-range and oversize onto one stockpile). The advantage for operators is that they are able to increase site safety and reduce operating costs when only two stockpiles are required. “The removal of the mid-range con- veyor means lower fuel consumption and less wear as the conveyor belt is not in use. It also allows more space and freedom of movement for plant equipment such as front-end loaders around the unit, meaning less risk of collisions. The ST2.8 can also be fitted with a variety of media ranging from Bofor bars, wire mesh, rubber and finger screens,” says Abelho. The range is completed by Metso’s line of inclined screens, including the ST3.5, ST3.8 and ST4.8 – with the initial two models being double deck screens and the last model being a triple deck version. The units are used for finer screening applica- tions (a separation of 70 mm or less) and can accept a feed size of 200 mm maximum. Screen choices Quality parameters in screening when it comes to aggregate pro- duction are normally driven by size and shape. How does the end result help determine what type of screen you need? Ravenscroft says the quality parameters of the aggre- gates, in terms of size and shape, would determine how efficient the screening needs to be. “This would then guide us as to whether a customer would need a horizontal or an incline screen. For shape, there is different screening media that can be used to achieve different shape parameters,” says Ravenscroft. Kukard says the correct screen size is determined by the tonnes per hour required by the end customer, the amount of final product sizes as well as the screen apertures (for example, 350 or 500 tph, three or four final products, road stone or concrete stone final product). Sukdhoe says the end require- ment by the end user will assist in determining what screen type and screen media is required. “For exam- ple, if the customer requires a qual- ity sized aggregate we will offer our

high-energy S Range screens with screen mesh specified to the size required by the customer. We can also assist the customer in blending the material if they require. Should the end user require a larger size of product where quality is not that important, such as gabion stone or a G5, we can offer a high-energy heavy duty scalping screen,” says Sukdhoe. Abelho is of the view that the first considerations would be the size of the feed and the product size that is required. “We have different horses for different courses, so is a scalper, primary or secondary screen required? Often you will require a combination of the two – a scalper upfront to carry out the general sepa- ration, followed by a screen to make the fine cuts,” says Abelho. Abelho adds that, with some exceptions, the screening media will have a larger effect than the type of screen when one is target- ing the size and shape of a product. “If the size requirements are very stringent with a very narrow toler- ance for deviation, then a horizon- tal screen would typically provide a much more accurate cut (separa- tion) than an inclined screen. For fine screening where open area is a challenge, dependent on the final specifications, screening below 3 mm is often performed with the general-purpose inclined screen using media such as piano wire, but operational considerations, such as a very abrasive feed, may make this uneconomical and a linear screen with poly-panels may be advisable,” says Abelho. Abelho adds that while screen- ing in a wet or dry configuration is available on most screen types, the cut-size will make a difference on whether you would opt for a wet inclined or wet horizontal screen, product is only part of the solution; having a partner who understands the challenges and is able to adapt to changing operational conditions is key to ensuring that not only are you achieving your production targets, but also maximising profits by lowering operating costs and downtime and ensuring longevity of assets,” concludes Abelho. l as well as the type of media. “In summary, having a good

material need to be separated,” says Abelho. Metso range Pilot Crushtec also stocks the Metso CVB-M and CVB-PM screens, which are compact and designed specifi- cally for the aggregate market. The most popular in this range are by far the CVB1845-3M and the CVB1845- 3PM – both 1,8 x 4,5 m triple-deck inclined screens. The CVB1845-3M model is a screen designed for secondary and tertiary screening and can handle a feed size of up to 150 mm, while the CVB1845-3PM is considered a primary screen that can handle material >300 mm. “Although the screens are the same size, their design is fundamentally different. For example, the second deck on the -3M is mounted above the shaft of the screen, while on the 3-PM the same deck is mounted below the shaft. This makes a significant difference to the units’ centre of gravity,” says Abelho. However, both units make use of Metso’s revolutionary MV Modular Vibrator Motor, which is a grease lubricated modular cartridge vibrat- ing motor. Several advantages of MV Vibrator Motors include a compact 4-bearing system which translates into extended bearing life and lower downtime; rapid and safe change out or repair; and an easy rebuild/ exchange programme, which means less downtime and contamination. “We also offer a range of the Metso mobile screening equipment targeted at contractors. Our range comes stan- dard with the Metso EPS (Extended Protection Services) which offers our clients (and in turn their customers) an additional peace of mind in terms of equipment reliability. The EPS is an extended warranty that covers major components for 5 years or 10 000 hours – this is alongside the stan- dard 2-year/4 000-hour warranty,” says Abelho. Abelho adds that the jewel in the crown is without doubt the Metso ST2.8 mobile scalper, “an absolute beast of a machine” which can operate at stroke of up to 15 mm, “at least 50% more than any equivalent screen on the market”. It is able to handle a feed size of 600 mm (at an SG of 2,6 t/m³).

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QUARTER 3 - 2019 MODERN QUARRYING