PowerX Equipment design and install a new Wash Plant for Glendinning at Linhay Quarry.
Located in Devon, near Newton Abbott, Linhay Hill Quarry is owned and operated by Glendinning, who is the largest independent supplier of quarry, and concrete products to the construction trade, local authorities, and general public in Devon and Cornwall; with supplied aggregates amounting to 25% in Devon.
Founded in 1958 today it operates with a staff of over 200, over 50 vehicles, 2 quarries and five sites and is still very much a family business.
Investment:
Linhay Hill quarry is where the company extract and process Devonian Limestone with their up-to-date production facility.
Recently an aged wash plant came up for review and the decision was made to replace the plant which after due process PowerX Equipment were chosen. Founded by industry specialists with decades of experience in this market PowerX Equipment are recognised as a market leader and the next generation in aggregate and mineral processing.
The new plant was installed and commissioned in September 2023, with civils completed by Glendinning.
Ensuring the product:
Designed to produce concrete sand predominantly and some clean single size aggregates the primary function of the new plant is to make this concrete sand and clean sized aggregates of 6/10/14/20mm.
The washing material is part overburden which previously could not be used for any other purpose is fed into the plant. This allows them a better utilisation of all the minerals that they are having to move around – for instance, the top section of the current dig would have been difficult to deal with subsequently going to tip. With the new wash plant, they are now able to wash this material and make a good clean aggregate from it.
Furthermore, by producing a concrete sand this has reduced their reliance on their silver sand as the new concrete sand can now be substituted in the mix eliminating the purchase of imported silver sand for their concrete.
The main element of the new wash plant is the sand plant which has been designed to recover maximum fines passing 63µm, which Glendinning need to keep in their product, as it is more advantageous to keep that fine element in the bottom of the concrete sand. To achieve this the sand plant was designed with two adaptable hydro-cyclones which work at a much higher pressure which enables them to draw the fines into the product and not lose any fines to the pond.
Plant process:
As-dug material is delivered by wheel loader into a 30-ton capacity heavy duty hopper. Material is the then fed up a 36m inclined feed conveyor and delivered onto the 6.1m x 1.6m double-deck rinsing screen, where sand drops through the bottom deck with any aggregate greater than 20mm returned on a 36m closed circuit conveyor, under an overband magnet, into a surge bin before being fed in to an impact crusher via a vibratory feeder, with the crushed material returned back to the primary wash screen via the feed conveyor.
Material then passes onto a secondary feed conveyor into the twin-shaft log washer with the blades conveying the material from the feed end of the scrub.
Any organics such as roots are floated off to be dewatered over a 1.8m x 0.6m trash screen. The trash is fed into a skip. Any water, silts and fine sand liberated by the scrubbing process pass through the modules on the trash screen into a sump and pumped to the sand plant to maximise recovery.
The sand plant has two, rubber lined cyclones fed by a single 200/150 pump. The cyclones are manufactured in such a way that the choice of three feed tubes, three vortex finders and seven apexes, give the flexibility to fine tune the end product, to the customer requirements. The overflow with minimal losses goes to the lagoon and the underflow is deposited onto the 3.7m x 1.5m dewatering screen before being fed via a polyethylene lined chute onto a 15m conveyor to stockpile.
John Collins – Technical Director at PowerX, commented, “The sand plant was designed in this way as not all feed materials and end result requirements are the same. All of our sand plants are designed to be application specific and not a standard one size fits all ethos. The extra silt requirement reduces the import of other sands, reducing the Glendinning carbon footprint. This is due to the cyclones running at a higher pressure which allows more fines recovery from the underflow. Both cyclones are linked back to the computer with pressure sensors so they can be seen in the office or control cabin.”
The Scrubbed aggregate exits the main discharge of the log washer onto a 2.4m x 1.2 dewatering screen, again the liberated fines pass through the modules and into the sump to be pumped to the sand plant for reclamation. The transfer conveyor feeds the aggregate onto the final 4.9m x 1.5m double-deck dry sizing screen. With the bottom deck split 50/50 - the first half makes a clean 4/6mm product with the second half of the bottom deck making a 6/10mm clean product. The top deck of the machine is decked out to produce a 14mm clean through the top deck, with a 20mm off the end so although a double-deck it is making four clean aggregates. The reason that this screen can do this is the plant has all the material is sized to -20mm on the Rinser.
Material is then delivered to stockpile by four 15m conveyors.
The whole plant consists of heavy-duty galvanised steel support structures, conveyors with galvanised lattice frame construction and covers and galvanised walkways throughout.
Ian Hanniford – Control Systems & Project Engineer, “We are very pleased with the new plant, the product is very good and to the required specifications. We could not fault the build and commissioning of the plant which was all completed by the PowerX engineers who were all committed to working to the very highest standards.”