Continuous vertical conveying has its challenges, notably the efficient use of space. White County Coal (WCC) mine in Carmi, Ill., chose the POCKETLIFT vertical conveyor because it helped to double the conveying output in the mine without the need to sink a conveyance shaft with standard dimensions. Instead, the new shaft measures nearly 12 ft in diameter. Consequently new coal deposits could be accessed and transported without making large-scale investments or taking up a lot of space.
The company has been using POCKETLIFT since 2002, and the system has transported over 38 million metric tons of coal to the surface and has impressed people with its clear benefits versus a traditional skip hoist system. In terms of conveying height and capacity, this conveyor system offers lifting heights to 700 me (2,300 ft) and capacities to 6,000 metric ton per hour.
Its compact structure makes it an attractive proposition for the mining industry. While other transportation systems like skip hoists are made entirely from steel, the POCKETLIFT conveyor is more lightweight. The system comprises two narrow steel-cord belts connected by rigid triangular cross-bars. These cross-bars also have a guiding function. The material is transported in fabric-reinforced rubber pockets that are bolted to the middle of the cross-bars. The pockets can be installed and removed individually. This structure makes the conveyor more compact than conventional conveyor systems and for handling materials in mining shafts.
Compared with conventional conveying systems, POCKETLIFT uses a lower driving power. Due to the continuous mass flow, less driving energy is necessary. The cost per metric ton of bulk material conveyed is below the average—energy consumption per metric ton and 100 m (328 ft) of lift height stays below 0.3 kWh. This allows mine operators to save on energy supply. Thanks to low noise emissions, the conveyor system has a much smaller impact on the environment than other products.
The system for WCC has a lifting height of 276 m (905 ft). It is approximately a quarter of a kilometer in height and transports up to 1,815 metric ton an hour. With 782 pockets, the conveyor belt has a total weight of around 100 metric ton and is lightweight compared with conventional shaft conveyor systems. In addition, WCC was able to reduce the head gear of the shaft to a minimum.
ContiTech Conveyor Belt Group
Filed Under: Design World articles, Conveyors, Linear motion • slides, Motion control • motor controls