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FEATURE supports the moving load. The return run does not require air support, and many systems incorporate conventional idlers on the return side. By using standard take‐up drives, chutes and sup‐ port structures, the air‐supported design allows conver‐ sions of, or connections to, existing standard belt conveyors. At the Newberry plant, the 24‐in. wide (610 mm) air‐ supported conveyor negotiates a vertical curve to ele‐ vate the load 25 ft. (7.6 m) over the 290‐ft. length (88 m) from the bottom of the clinker silo to the top of the load‐out structure. Capacity is set at 400 tph (363 tons) of 1‐in. minus (25 mm) material, with a belt speed of 350 ft.‐per‐minute (106.7 m‐per‐minute). The troughed conveyor is moved by a 25 hp (18.6 kW) drive motor, and the air‐support system uses a 15 hp (11.2 kW) blower to raise the belt. The air‐supported design from Martin Engineering elim‐ inates maintenance issues such as idler lubrication and belt alignment, and the modular system allows replace‐ ment of existing conveyor sections with CEMA standard construction. Air‐supported and conventional roller sections can be mixed to accommodate loading zones, tracking idlers, belt scales or other needs. With its sta‐ ble path, an air‐supported conveyor can operate at a steeper incline than roller conveyors, which can reduce the overall length and installed cost. Two belt feeders at the Newberry plant meter the mate‐ rial through rolling blade gates to deliver a consistent load to the conveyor and prevent the "starve and flood" conditions that can impede smooth operation. The mate‐ rial flows into ceramic‐lined transfer chutes, also sup‐ plied by Martin Engineering, then onto the conveyor. As the material enters the discharge tower, it passes over a belt scale and into a retractable dustless discharge chute, which extends down into the railcar opening. The discharge chute is installed on a positioner that delivers up to 6 ft. (1.8 m) of travel perpendicular to the tracks to accommodate various loading hatch arrangements. An in‐ sertable dust collector is installed at the head pulley to catch any material that becomes airborne. "Fugitive material control was a critical element of this system," Kerns added. "We needed to prevent the need for maintenance in the confined space location, but we also had environmental objectives. Alligators and other protected species in- habit this area, and we wanted to ensure that dust didn't migrate from the process." Positive Results Results at Vulcan's Newberry plant have been very posi‐ tive, and the company reports virtually maintenance‐ free service from the air‐supported system. "The product condition is excellent from the smooth han‐ dling," Kerns said. "And with the fully‐enclosed system, there is no contamination of the conveyed material or escape of fugitive dust." E Vulcan Materials Vulcan Materials Co., Birmingham, Ala., is the na- tion's largest producer of construction aggregates and a major producer of other construction mate- rials, including asphalt, cement and ready-mixed concrete. Thompson S. Baker Cement Plant 4000 N.W. County Road 235 Newberry, FL 32669 Phone: 352-472-4722 Fax: 352-472-2449 www.vulcanmaterials.com/thompsonbaker Contacts: ■ Operations: Chris Horner, 352-472-4722, ext 130 ■ Q.C.: Don Levonian, 352-472-4722, ext 120 ■ Sales: Scott Baker, 813-748-5000 The 24-in. wide (610 mm) air-supported conveyor from Martin Engineering rises 25 ft. (7.6 meters) over its 290-ft. length (88 meters) from the bottom of the clinker silo to the top of the load-out structure. 20 ROCKproducts • OCTOBER 2011 Products: ■ Masonry Cement ■ Portland Cement ■ Stucco Cement www.rockproducts.com