A Hercules heavy-duty trommel screen, one of four units sold to Damon Pursell Construction of Liberty, Mo., is busy processing rock for use in rebuilding the damaged levees of New Orleans.
The trommel is on contract for 10 months to a quarry in Pine Bluff, Ark., and is producing four sizes of material from an abrasive blast sand rock, which has a silica content of 85 percent. The unit is producing about 450 tph of various-sized rip rap material, which is transported down the Arkansas river by barges to the quarry company’s own distribution center. There, large tonnages of the rip rap material are sold for the rebuilding of the hurricane-damaged levees around New Orleans.
The mobile trommel was initially on rental for just two months as part of a test period, but the customer was so pleased with its performance that the rental contract was extended to 10 months, according to the manufacturer.
The trommel, a model HT182M, which is rated at 500 tph of feed material, was sold and supplied by Hercules Trommels USA, Liberty, Mo. It was manufactured by parent company, Stelex Construction Equipment Ltd, of Whitchurch, Shropshire, U.K., and is the first of its type to be operated as a rental unit with the U.S. market.
The machine is one of a new generation of road-towable trommel screens that have been designed for long- or short-term contracts within the quarry and mining industries. The unit is a modular design with relocation in mind, and can be easily moved along a blast-face wall or relocated to a new site.
The feed hopper is made of Hardox steel to provide high wear resistance and can accommodate 16 ton, or, with extension plates, up to 33 tons. End and side plates are folded down to reduce traveling height.
A variable speed-reciprocating hydraulic plate feed table, which is supported on rollers beneath the feed hopper, feeds material into the barrel via hydraulic rams that can be adjusted to the required tonnage of between 250 tph and 500 tph.
The 1.8-meter diameter barrel (made up of four 2-meter long segments) is manufactured from high-grade steel bars welded to form segments, which are bolted together. The apertures are made to suit individual customer requirements.
The barrel is supported on four steel rollers, two of which are driven by heavy-duty, variable-speed hydraulic motors (no drive chain or sprocket to maintain). The barrel’s rpm is fully adjusted to suit the type of material that is being fed to the trommel to ensure optimum cleaning of clay contamination and high moisture content materials at all times.
On this particular site, and for operations where a longer-term contract may be planned, a specially engineered support frame, located on a pre-formed concrete pad, allows the unit to be lifted off its wheels. This provides load out bays, which eliminate the need for conveyors.
The dirt or fines in the feed are discharged through the first barrel segment, while the clean rock travels down to be graded by the different apertures in the barrel. Oversize, which can be lump sizes of 900 mm, are discharged through the end of the barrel.
Mike Pursell, the machine’s owner, purchased his first static trommel in 2000, after which he saw a need in the industry for a heavy-duty mobile trommel for the rental market. He now has three units out on contract and has a further two machines on order from Stelex.
Pursell says, “All the machines have performed above our expectations, working 12 hours a day and giving 100 percent reliability, with very low maintenance costs. Our investment in the trommels was a good decision, and we are now working together with Hercules Trommels USA to service the needs of the growing U.S. rental market.
Hercules Trommels USA, www.herculestrommels.com
