Published in the December 2007 American Longwall Magazine
Sweetwater County in Southwestern Wyoming, near Rock Springs and Green River, derived its name from the sweet groundwater in the region. The sweetness can be attributed to the world-class deposits of trona ore found and mined there. Trona ore is not abrasive, but when water is added to control dust, the salt dissolves and leaves a very abrasive “matrix” behind.
This matrix can dry and harden into extremely stiff and abrasive material that can severely threaten the life of conveyor belting covers – and the lifeline of the mines.
Fenner Dunlop Americas has been providing its MineHaul conveyor belt to this market for over a decade and remains a primary supplier to the region. The conveyor systems can be as long as two miles from end to end, and the abrasion can be severe putting a high demand on both the top and bottom covers and carcasses.
Fenner Dunlop Americas approached this region with optimism and confidence that its MineHaul carcass construction and cover compounds were going to perform exceptionally in these demanding conditions. Production performance guarantees were offered to key partners in the region and belt orders were delivered.
Since installation, periodic monitoring of the belt’s cover thickness with ultrasound devices has been performed on mainline conveyor systems with measurements recorded across the belt width on the top and bottom covers. Fenner Dunlop Americas reported every inspection resulted in improved belt life and reduced cost per ton for the end users.
In figure 1, the graph shows the belt installed by Fenner Dunlop Americas in early 2004. The cover wear in the bottom center between September 2004 and June 2005 was attributed to worn rubber impact rollers at the loading area. These were replaced with solid steel rollers – at Fenner Dunlop’s request – that proved to stop the unusual center wear.
At a different mine in the region, a longwall production belt was recently inspected using the same ultrasound technique. This system, when fully extended, contains approximately 24,000ft of 54in four-ply 1000 Plies Per Inch Width (PIW) belting with 3/16in top and 1/8in bottom covers. The system contained belt purchased from both Fenner Dunlop and a competitor since November 2004. Fenner Dunlop has provided Minehaul 4-1000 3/16 x 1/8 Fire Retardant Abrasion Resistant (FAR) belting while the competitor provided 4-1000 3/16 x 1/8 abrasion resistant belting.
A total of seven sets of measurements were taken at intervals of at least 500ft to ensure that a different roll of belt was being sampled each time. Three rolls of the competitive belt and four rolls of Fenner Dunlop belt were measured for top and bottom cover wear. Figures 2 and 3 show the top cover wear data for a competitor and Fenner Dunlop Minehaul. For the Minehaul FAR belt, the cover wear is concentrated in the loading area of the belt and wear outside this region is minimal.
In figure 3 a competitor’s top cover thickness is graphed. The belt was delivered to the mine in June 2006. The belt shows unusual cover wear along the edges. In addition to the normal loading wear, all three rolls of its abrasion resistant compounded belt that was inspected showed severe cover cutting, gouging and chunking. No such cover damage was observed in any Fenner Dunlop MineHaul belting, according to the company.
A similar trend was found with the bottom cover wear, with the Fenner Dunlop belt holding its thickness.
In all testing undertaken on its products Fenner Dunlop Americas said its conveyor belting had proven to be a longer lasting, lower cost per ton alternative.
