CONVEYING
AUSTRALIAN MADE CONVEYOR WEIGHING SYSTEMS AIM TO
ELIMINATE ‘BAD BATCHES’ With COVID-19 continuing to bite, it’s challenging enough for quarries’ loads and deliveries to comply with regulations and recipe requirements for construction. A Melbourne-based manufacturer of weighing solutions is providing accuracy and reassurance through its products. The belt scale is utilised midway through the conveying process after the feed is first delivered to the belt.
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onveyor systems are an integral part of industrial mass production, enabling multiple items to be dispensed in the supply chain. The key for many organisations is running them seamlessly and efficiently. While they may be contending with crushed rock rather than manufactured goods, quarries are reliant on good working conveyor systems and must comply with prescribed loads in their end products. This has been ratcheted up in recent years with the introduction of Chain of Responsibility/gross vehicle mass obligations across Australian jurisdictions. Indeed, quarries can be held accountable for incorrect weights on a tipper truck, even if that truck is not part of its own fleet and being managed by a third party. Further, accurate readings are important for quarries that need to provide the right grades and formulae for cement production and road construction materials, as dictated by roads and transport authorities around the
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Quarry February 2022
country, eg VicRoads, NSW RMS, TMR, etc. Therefore, accurate readings on throughput are essential not only to a quarry’s productivity but its reputation for reliability and quality end products. Conveyor belt scales and weigh belt feeders play an important role in minimising the risks for quarries of producing “bad batches” of end product. As Barry Gamble, the business development manager for Tecweigh, an Australian manufacturer of custom-engineered weighing solutions, told Quarry, the two devices are essentially one and the same – except one is designed for existing conveyor infrastructure while the other is custom-designed by Tecweigh. “The customer has his own infrastructure running,” Gamble said of the conveyor belt scales. “Each scale has plus minus three idlers which are shimmed level with the scale to ensure a smooth transition of the product over the weighing area. The centre idler is removed and remounted on the belt scale on a spreader bar connecting the two load cells and this becomes the weigh idler. We combine that weight information with belt speed data from the speed sensor which shows us the tonnes per hour. “If you’re installing a weigh belt feeder, that’s when we provide both the conveyor infrastructure and drive mechanism.”
BELT SCALES The belt scale is best utilised midway in the conveyor, away from any extraneous forces where the product is first delivered to the belt. “We let the product settle down after it has been dispensed, ” Gamble said. “It’s what we call ‘shimmed and levelled’, this allows us to achieve the stated accuracy. “Whether used in conjunction with a screen, crusher, portable stacker, pugmill or truck, the result with the throughput is the same. We can
tell you how many tonnes per hour passes across the belt scale.. However, it’s possible to have separate belt scales sorting product sizes, eg 5mm coming across one scale, 7mm across another, and 10mm across a third. That’s useful if a customer like VicRoads requires a recipe for an aggregate mixture of 5mm, 10mm or 15mm.” Tecweigh’s signature belt product is the WY15 single idler scale which has an accuracy of +/-0.5 per cent, enabling the end user to determine instantaneous and total product flow in tonnes per hour or other selectable units. For more precise accuracy, they can also opt for the WY25 dual idler at +/-0.25%. The WY15 and WY25 are built primarily from powder-coated mild steel but there is also an option for stainless steel in harsh environments. Their other key features include self-storing calibration weights, user-friendly electronic processors, built-in relays for remote counting, belt slip detection and rate alarm tripping sensors, and 4-20mA scaling calculators for remote rate display.
WEIGH BELT FEEDERS Gamble said weigh belt feeders are suitable in blending aggregate products to a customer’s formula, in cement production or truck filling. In particular, the weigh belt feeder is shorter and more flexible than the traditional conveyor and therefore it can be adapted to suit purposes such as truck filling. For example, weigh belt feeders can be fitted to a range of silos at the end of the conveying process to facilitate easier and more efficient filling of trucks en route to the weighbridge. “You could have a silo of 5mm product, a silo of 10mm, and a silo of 15mm, and then you can dispense a certain amount of each one as per the quarry customer’s requirements,” Gamble explained. “The benefit of the truck filling is it guarantees
