Scottish aggregates suppliers, Tennants of Elgin, have long since opted to keep a fleet of ageing crushing and screening equipment running to produce the aggregates they require for their concrete batching plants and aggregate supplies.
Addressing Ageing Fleet and Production Bottlenecks
Recent events within the company have seen Gavin Tennant stepping up to take the MD’s role within the company and with this responsibility, he has started to look at the overall running costs and production abilities from the ageing fleet. “Sadly, we lost my father recently and whilst his methods were fine to supply limited volumes of aggregates for our own requirements, increasing downtime from the plants and an increasing requirement to buy in material we couldn’t produce inhouse made us rethink our policy of running older machinery.” Gavin said. “Replacing all of our older kit in one fell swoop wasn’t an option, but we have made a start in our Lhanbryde quarry where we realised we could improve production figures quickly.”
Partnership with Molson Finlay Scotland
The first port of call for Tennants was with Mike MacKenzie at Molson Finlay Scotland who specialises in the crushing and screening equipment sold by the company. “We have looked at all of Tennant’s operations and came up with a list of machines we could integrate into their operations to improve not only their productivity, but also increase the variety of material produced.” Mike commented. “Lhanbryde quarry was the quickest and easiest site to address the issues and working with Gavin and his team, we have introduced a new Finlay 684 tracked incline screen.”
Finlay 684 Tracked Incline Screen Drives Production Rates
The Finlay 684 is one of ten incline screens in the Irish manufacturer’s range and whilst not the largest, the addition of this machine at Lhanbryde quarry has seen the production rates sky rocket to a point where the team have been able to reduce the operating hours of the plant every week.
Technical Specifications of the Finlay 684
Powered by a StageV CAT engine, the Finlay 684 incline screen is designed to provide a consistent grade of material day in day out. The material is loaded into an 8m3 hopper where a conveyor moves it steadily up to the two-deck incline screen. The 684 uses a 4.3 x 1.7m screen box which can be hydraulically inclined from 18° to 37° allowing material to pass through at different rates depending on the quality and quantity desired. The main conveyor is 1m wide and uses three anti-rollback plates to plates to stop material dropping back and blocking the flow. The sides of the conveyor are also fitted with substantial side skirts to stop material falling off. There are two other material conveyors on the machine, one on each side of the screen box. The fines conveyor on the left hand side of the machine is 1.2m wide and extends to a maximum height of 4.15m above ground. This will effectively give over 106m3 of stockpiling capacity without the need to move any material. The medium grade conveyor on the right hand side of the 684 incline screen is slightly narrower at 650mm and will allow up to 194m3 of stockpile below it. Tennants have opted for a 24mm woven mesh on the top deck with 6mm piano wire mesh on the lower which now allows them to produce three consistent grades of material. These are currently oversize off the main conveyor, and 10mm, 16mm and 20mm sand. Whilst the oversize is crushed is former river stones, this is placed to one side to await crushing when there is a sufficient volume. Mid-size material is graded to a range of sizes with the fine material stockpiled or fed through the veteran Finlay wash plant to further process the sand. In total, the site now produces 16 different material sizes, more than double it had in previous years.
Future Plans and Site Optimization
Currently using a 14 tonne excavator as the site’s prime mover, the increased productivity of the Finlay incline screen, over the older machine, has put the smaller excavator under pressure to keep up. “Upping the size of the digger would allow us to improve the production on the site and to use the Finlay incline screen to its maximum ability, but that’s something we may do in the future.” Gavin comments. “What we are thinking of doing is creating sufficient products at Lhanbryde before moving the Finlay incline screen to undertake a spell at one of our other quarries. Not only will this allow us to increase the range of materials we can supply from our hard rock sites, but it will also reduce the need to add additional kit for each quarry if we are able to share it between sites.”
Impact on Bottom Line and Future Potential
The addition of the Finlay 684 incline screen has seen the company invest in their first new piece of kit for many years. The almost instant increase in productivity has made a huge difference to their bottom line as large volumes of sand for their concrete batching plants can now be produced in house. “The Finlay incline screen has made a big difference to the way we operate.” Gavin commented. “It has opened our eyes to the potential we now have in our own sites.”
Excellent Service from Molson Finlay Scotland
Whilst this is the first machine supplied by the Molson Finlay Scotland team, it has hugely impressed the entire management team with its reliability and productivity. This has been echoed by the support and service Molson Finlay Scotland have given the company. “Mike has taken some time and effort into getting exactly what we wanted to benefit the quarry.” Gavin commented. “Their back up and service is excellent and the assistance from Mike and his team to tweak the incline screen into its right specification and position helped us immensely.”
