BTB 31: WHAT BOTTLENECK?
Published on: Sunday 1st July 2012
— Gary Olsen, factory representative, international sales
Industry professionals in Brazil, Chile, Uruguay, Australia, South Africa and any other country growing short rotation tree crops strongly appreciate the challenges they are faced with when it comes to the debarking of eucalyptus and other hardwood species grown for pulpwood. Aside from the economics of handling large quantities of small volume trees, one must consider the difficulties related to the bark removal of each particular species. Another complicating factor is seasonal variation; it is considerably more difficult to debark in dry conditions. Conversely, the flow of moisture through the cambium when conditions are wet facilitates easier debarking. Combine some poor stem form in certain species like Acacia mangium, the pulpwood species of choice in Indonesia, or Acacia mearnsii, a common plantation species in South Africa, and you have a single grip harvesting head nightmare and potential for a real operational bottleneck.
Enter old technology, repackaged into a clean, safe and efficient four drum flail debarker and chipper if required. Combine it with tried and tested Tigercat multi-stem harvesting equipment and we have a near perfect solution to this age old headache.
If one looks at the cost structure of harvesting eucalyptus using either a pure cut-to-length (CTL) or a partial CTL system, it becomes clear that the biggest opportunity to drive down harvesting costs lies in the debarking component of the working cycle.
Dealing with small trees from a felling point of view has just about been perfected through the use of high speed, high accumulation disc saw or shear heads mounted to either a wheeled or tracked carrier. An 860C track buncher with a DT5000 disc saw head in Brazil or an 855C with a DT2000 shear in Australia offer the perfect solution, packing from five to as many as eleven trees (depending on tree size) into the accumulating pocket, essentially turning multiple small stems into a single big tree.
When bunch sizes are maximized, this felling process facilitates unmatched productivity of the subsequent extraction process with the powerful pulling capacity of the Tigercat 630D skidder or the unmatched six-wheel drive 635D. Gathering multiple bunches to utilize the grapple size and pulling capacity is paramount to fully optimizing the productivity potential of these skidding brutes. Undoubtedly adding to the effectiveness and efficiency of the skidders when delivering to and working around the flail is the hydrostatic drive system combined with the unique Turnaround seat. It allows for virtually instant forward and reverse directional changes on the fly without sacrificing operator comfort, ergonomics or visibility.
Productivity levels previously thrown about for infield flail debarking systems sat at 50-70 tonnes per hour. The bar has been raised thanks to the very well balanced system that debuted in Brazil, using an 860C with a DT5000 disc saw, a 635D skidder and a CBI 604 four drum flail debarker. A Tigercat T250B with a Rotobec powerclam grapple removes the debarked stems from the back of the flail and stacks them for a second grapple saw equipped T250B which bucks the trees to 6 m lengths. Thus five machines and five operators are producing a mammoth 120 tonnes per hour in 0,14 m3 sized trees. An equivalent CTL system would typically require eight harvesters and six forwarders to produce the same volume.
Gaining in popularity not just in Australia but also South Africa and Indonesia is the ER boom equipped Tigercat 855C configured as a feller buncher with the third generation DT2000 high speed shear. The machine of choice in Australia, it stands up to the tough task of severing the hardwood tree in less than a second while leaving very little fibre behind on the remaining stump. The accumulation area provides the opportunity to pack five to seven blue gums, (as they are known in Australia) before dumping the load. The shear head, while 10-15% less productive than a disc saw has the advantage of lower operating costs.
Tigercat and CBI demonstrated the full system with in-field chipping at the recent AUSTimber show in Mount Gambier in March. The CBI 604 flail was combined with the Magnum Force DC 754 disc chipper and it was evident straight away that this added machine makes the system even more productive – approaching 150 tonnes per hour. This is great news for the Tigercat machines as the system now becomes even more balanced and both the buncher and skidder operators can work flat out with no restrictions — just keep the trees coming. The 635D worked around the fl ail dropping trees, positioning them and then using the innovative spoon style grapple tongs to return bark back into the field – all under the watchful eye of the 215 knuckleboom loader operator. Mounted on the CBI flail and especially designed to feed its hungry jaws, the Tigercat 215 has perfect boom geometry, ensuring that the monster never goes hungry when the demand is there.
Brazil, Australia and no doubt many other places in the near future will see this cost effective harvesting solution work its way into the industry as people come to terms with the capability and productivity of the system. New projects are already accepting this format as the harvesting system of choice and designing mill yards to receive what the logging operations can produce most cost effectively — high quality chips. Contrary to what many people believe though, one size does not fit all. This harvesting solution in its entirety might not be for everyone and for some, only parts of it might be applicable. Nevertheless, the proof has been in the eating. We’ve seen what a true full multi-stem harvesting system with a debarking component can do and it is a winner.
KBM owner Daniel Hermosilla talks to BTB about the equipment and human resources required to produce chips efficiently in Chile.
Samantha Paul continues with her second installment in the new Between the Branches Feature, Women in Logging. Samantha profiles Wendy Fennell, CEO of Fennell Forestry, headquartered in Mount Gambier, South Australia.