Whatley has been operating since the 1960s and is the largest of Hanson UK’s quarries. It is situated between the villages of Mells and Chantry in the Mendip Hills Natural Character Area around four miles west of Frome. It employs over 60 people directly, along with a wide range of support staff and contractors. The quarry supplies crushed limestone aggregate to local markets by road, and to depots in London and South East England via a dedicated rail link. It operates 24 hours a day and produces between 4 to 5 million tonnes of aggregate a year. There are further on-site plants producing asphalt and ready-mixed concrete. Limestone reserves are in the order of 100 million tonnes. The site extends to 173 hectares, of which 120 hectares comprises of the limestone extraction site.
Whatley Quarry approached Vulcanising South West Ltd on the 15th May 2019 with the view to carrying out a belt calculation on CV07 conveyor. The maximum expected life of the belt 1000/4 6+2 (of unspecified origin) was on average 6—12 months with a number of repairs required during this period especially the splice. Each repair carrying extra cost and downtime. C7 conveyor at Whatley Quarry is a horizontal conveyor carrying crushed limestone aggregate at a size of 63mm – 250mm. The conveyor is a key asset in the process as without this conveyor in operation all primary and secondary crushing operation is halted.
The snub roller diameters are too small for a 1000/4 6+2. Belt dimensions 98000 X 1200mm. Under normal running conditions, the belt carries between 500 and 1400 tons of material per hour depending on the number of crushers in operation. Average tonnage in normal operation is 1200tph. The average tonnage carried by C7 over a 24 hour period is 18,000t. The site is operational 5 days per week. With a maximum material size of 150mm, flowing onto the belt from a 600mm height, it was determined that a Dunlop 630/4 6+2 RA Superfort® or UltraX3 spec belt would be more than capable in dealing with the demands of this application. However, in light of the historical data, VSW decided to increase the spec to an 800/4 6+2, knowing that this would maximise the expected life of the belt whilst still falling within the range of Dunlop’s ‘Safety Factor’.VSW and Dunlop were certain that with the abrasive resistant ‘RA’ covers coupled with the correct tensile strength selection, Superfort® would offer a significant increase in lifespan as well as a reduction in downtime and operating costs compared to previous belts installed.
Superfort® 800/4 6+2 RA DIN Y, moulded edges
A report of our findings and analysis was discussed with Whatley Quarry and a quote requested for Vulcanising South West Ltd to supply and install Dunlop Superfort® 800/4 6+2 RA DIN Y, moulded edges. A technical data sheet provided was supplied to Hanson with our offer.
Splice and hot vulcanise on site
Prior to our team arriving on site a SSOW (Safe Systems Of Work) was completed by Craig Jones, our Health & Safety manager, and the safe installation planned in conjunction with the Hanson on site. On arrival, our team carried out a job-specific risk assessment and method statement prior to any work. In coordination with the team at Hanson all the lifting and handling equipment had been arranged for us prior to our arrival on site. The splice was hot vulcanised using our Almex press.
Statement from Hanson
In June 2019, a new belt was ﬁtted. On this occasion, the belt was supplied by VSW and the belt provided was a Dunlop Superfort 800/4 6+2 RA.
This belt was operational for 12months and only changed due to a mechanical failure of a liner plate cutting the belt its full length 8 inches from its edge. During its time in operation, maintenance and inspection activities continued as normal with a signiﬁcant reduction in repair and belt maintenance costs. The Dunlop Superfort belt has outperformed the previously used belt and saved as a result on both downtime and additional maintenance costs during its life. Total belt life currently estimated at 18 months which is a 75%-100% increase in life against tonnage and an annual 45% cost saving.