PROBLEM
The NALCO refinery in Damanjodi produces approximately 22.75 Lakh (2,275,000) tons per year of processed alumina to feed its smelter for manufacturing aluminum. Processed alumina powder exits the refinery on conveyor 721, which is ~450 meters long and travels at 2 meters per second. The belt was experiencing serious tracking issues, which caused damage to the belt and structural components, as well as spillage along the conveyor path. Operators had been using self-aligning idlers from a local manufacturer, but were unable to effectively control the belt wander. The company needed to correct the issue to minimize fugitive material and avoid further damage.
SOLUTION
Martin Engineering technicians performed an audit on the conveyor and recommended four Martin® Trackers™ on the carrying side and five on the return side to stabilize the lengthy run. Rollers attached to the end of a sensing arm assembly ride both sides of the belt edge, detecting even slight variations in the belt path. Employing the force of the wandering belt, the arms automatically position a steering idler in the opposite direction of the misalignment. Transferring the motion to the steering idler through a unique parallel linkage requires less force to initiate the correction, so fine-tuning of the path can be continuous, active, and precise.
RESULTS
Utilizing a troughed idler support system on the carrying side of the conveyor to retain the proper angle and keep the load centered, the Tracker™ Upper Unit employs guide rolls that are mounted just one-quarter inch (6 mm) from the belt for high precision when making opposing adjustments to the idlers. The lower units are hung from the mainframe under the return belt every 70 to 150 feet (21 to 50 m) and use a single flat rubber idler to bring the belt back into alignment. The customer reports that the belt is now properly centered, and the results have been so positive that the company is planning to install additional Martin® Tracker™ units on its other conveyors.