The high energy, low emission pellets it will produce are destined for bulk export to Europe, where industrial power plants are steadily converting from coal-fired production to biofuels in order to meet stringent 2020 Kyoto Protocol commitments. 

Getting the wood in 

Green Circle’s production process starts here - in the woodyard and wood handling area. That’s where the Total Fiber Handling system from BRUKS Rockwood goes into action. The system is customized for Green Circle’s needs and has a number of unique features. 

“Although this is the biggest pellet mill in the world, some of the woodyard and wood handling equipment is about 50% smaller in scale than the average pulp or paper mill,” says Desmond Smith, Vice-President of BRUKS Rockwood’s West Coast Office. 

Most pulp mills stockpile about 4 million cubic meters of chips – Green Circle’s chip pile capacity is about half that. Consequently, the stacker/reclaimer is built to a smaller scale. The debarking drum and chipper, however, are standard production size.  

Green Circle uses mainly pulp-quality Southern Yellow Pine roundwood from local sources but the woodyard is fully equipped to receive wood chips, sawmill residue, bark or any other form of raw wood furnish. 

“The truck dumper and hopper are designed to handle a mixed bag of material and to accommodate future load sizes,” explains Ken Upchurch, BRUKS Rockwood’s Inside Sales and Aftermarket Manager. “The truck dumper capacity is 120,000 lbs. gross vehicle weight. Right now that’s as much as 40,000 lbs. more than load limits on Georgia, Alabama and Florida roads, but with fuel prices steadily climbing, those limits could go up over time.” 

The truck dumper is designed for 2 million life cycles and can rise to a 63 degree angle in less than two minutes. The hopper is a hefty16 feet wide and can handle 5,000 ft3 of material. It’s located 100% above ground, which required less excavation and saved on installation cost. 

Roundwood is offloaded by mobile unloader onto a conveyor which brings the logs to the infeed of a Fulghum drum debarker. Bark is collected on a conveyor below the debarker. The wood arrives with 50% moisture content and the system is designed to handle it as is, but what isn’t used immediately is staged in the large woodyard (about 40 acres) to be pre-dried using nature’s energy - the sun. 

The debarked logs go to a drum chipper which was developed by BRUKS Klockner to produce micro-woodchips for the pelletizing process. 

“Chips for pelletizing are much smaller than the conventional 30mm chips used for pulp and other processes,” explains Smith. “They’re only about 10 to 15mm in length. The pelletizing process changes the nature of the fiber and the result is a denser material than natural wood that burns much hotter and cleaner.”

The BRUKS Klockner drum chipper eliminates the need for one stage of chipping by creating a chip that is consistent and ready for drying and delivery to the hammer mill. This is achieved due to the fact that the drum chipper combines chipping with a screen plate ensuring maximum and consistent chip reduction. Unlike a disc chipper, which would not be able to produce a consistent 3/8” chip, the drum chipper and screen combination ensures a large percentage of 3/8” or less chips. Using the tiny chips saves significant energy and time compared to starting out with conventional chips, which would require another process to reduce them down to pelletizing size. The micro-woodchips can be dried and pressed into pellets without an intermediate grinding stage.