Fibre recovery and chip quality from De-barking and chipping fire-damaged stems
Dennis S. Araki Forest Engineering Research Institute of Canada March, 2002
Foothills Model Forest Publication Disclaimer
The views, statements and conclusions expressed, and the recommendations made in this report
are entirely those of the author(s) and should not be construed as statements or conclusions of,
or as expressing the opinions of the Foothills Model Forest, or the partners or sponsors of the
Foothills Model Forest. The exclusion of certain manufactured products does not necessarily
imply disapproval, nor does the mention of other products necessarily imply endorsement by
the Foothills Model Forest or any of its partners or sponsors.
Introduction
In 1999, the Forest Engineering Research Institute of Canada (FERIC), the Pulp and Paper
Research Institute of Canada (Paprican) and the Alberta Research Council’s Pulp and Paper
Group (ARC) initiated a two-year study funded by the Foothills Model Forest to address
industry concerns about making pulp from trees that had been burned in a wildfire and had lost
moisture. The study was designed to provide the forest industry with fundamental information
on the effect of fire severity and time-since-the-fire damage on wood chip quality issues, wood
pulping properties, wood chemistry and moisture content. In addition, the study would
quantify the operational issues related to the harvesting, debarking and chipping of burned
stems.
FERIC’s role in the study was to coordinate the project and examine the harvesting, processing,
debarking and chipping of moderately and severely burned timber two and three drying seasons
following the initial burn. Paprican’s role was to identify stems at locations where a prescribed
burn would occur for sampling prior to burning, immediately after burning, and at yearly
intervals thereafter. Paprican was also responsible for obtaining chip samples from the stems
sampled, pulping some of the chip samples in its kraft pulping pilot plant, testing the pulps
produced, and evaluating the wood chemistry and microscopy of wood and pulp. ARC was
responsible for pulping chip samples provided by Paprican in ARC’s chemi-thermo-mechanical
process (CTMP) and thermo mechanical process (TMP) pilot plants.
1
FERIC has completed its portion of the study. However, Paprican and ARC were not able to
complete their portion of the study because weather conditions prevented the prescribed burns
being undertaken. Alberta Environment and Peace River Pulp attempted prescribed fires for
two years but it was impossible or unsafe to start fires.
This report summarizes the studies FERIC has conducted during the past two years. The
objectives for these studies were to:
• undertake a literature review to identify issues related to the harvesting and utilization of
burned timber (Appendix I);
• quantify the quality of chips (size and size distributions, bark and charcoal content)
obtained from ring, flail and bin debarking fire-damaged stems after 2 and 3 drying seasons
and compare to chips produced from green stems;
• document the change in moisture content of fire-damaged stems recovered 2 and 3 drying
seasons after a fire;
• quantify the chip recovery and productivity when chipping ring, flail and bin debarked fire-
damaged and green stems.
To complete its portion of the study, FERIC during the summer 1999, located a deciduous-
leading mixedwood stand1 containing aspen (70% volume) and white spruce (30% volume) that
had been damaged by an August 1998 fire. The stand was located about 75-km southeast of
Slave Lake, Alberta and had an adjacent similar stand of undamaged, green trees. A ground fire
had destroyed the aspen roots but the aspen trees had an initial leaf flush in 1999 with small and
unhealthy leaves. In addition to root scorch, some of the white spruce had burned branches and
needles, and scorched bark. Although the stand was described as lightly burned (only the bark
2
1 A deciduous leading mixedwood stand refers to a stand that has >50% of its volume
comprised of hardwood (aspen) species and the remaining volume of conifer (white spruce,
lodgepole pine, black spruce).
exhibited fire damage with no evidence of burning occurring into the stem) this only referred to
the aspen component. The white spruce stems exhibited more severe burning and would have
been classed as heavily burned because the fire destroyed almost all the foliage and burned the
bark.
Logs were debarked using ring, bin and flail debarkers. The ring debarker at Slave Lake Pulp
is a Nicholson A5 ring debarker. It features 6 debarking arms that rotate in a clockwise
direction. Logs are chipped in a Nicholson 180-cm disc chipper powered by a 1650 kW
electric motor. The disc has 6 chip knife pockets and rotates at 450 rpm. The bin debarker
consists of a U-shaped debarking chamber that has a series of cylindrical rotors mounted
longitudinally on the bottom and/or side. Debarking plates are attached to the rotors at intervals
along the rotor length. The bin debarker tested in this study was a mobile prototype debarker
similar to the Deal Processor. Bin debarked logs were chipped in Slave Lake Pulp’s
woodroom. The flail debarker utilizes chains attached to a rotor to beat bark off stems. The
flail debarker is the debarking component of the Peterson DDC5000, a mobile delimber-
debarker-chipper designed to chip multiple, small-diameter stems. The debarker portion of the
unit features 54, 8-link chains attached to either two or three drums (6 rows of 9 chains per
drum) positioned above and below the infeed rolls to the drums. Bark, limbs, and broken tops
fall out the bottom of the unit while the debarked logs are directed into a Precision disc chipper.
The DDC5000 model utilized during the summer study had two flail drums and the unit used
during the winter study had three flail drums.
Study Method
FERIC was unable to harvest stems that had one season of drying after the fire. To get this data
FERIC used results from earlier studies it had done. Stems that had experienced two and three
dryings seasons after fire damage were recovered from about five hectares of the reserved
Slave Lake stand. Twelve truck loads of logs were harvested in August 1999 and transported
to, and stored at, Slave Lake Pulp’s logyard for further processing. During the study, FERIC
encountered some operational problems with access to, and use of, the three debarkers. Where
productivity was not determined, FERIC was only able to do chip analysis.
3
At the pulp mill, the burned logs were divided into large and small butt-diameter classes. For
aspen stems, butts less than 20 cm were considered small diameter while the spruce had a 25
cm butt diameter limit. The green aspen and spruce logs samples were used as the control. The
logs in each class were weighed prior to debarking and chipping. A sample of the logs in each
class was manually scaled to determine the average volume, and a log count for each log class
was recorded. A sample of logs from small and large diameter classes were selected for ring,
bin, and flail debarking, and the selected logs were transported to the appropriate debarking
location.
A Cat 966 front-end loader placed the logs being processed by the ring debarker onto the infeed
deck of the woodroom. Total debarking and chipping time for each log class was recorded.
The chips that were produced were dumped into a chipvan and weighed on the millyard weigh
scales.
The logs for the bin debarker were bucked into short logs between 3 and 5 m long and loaded
into the debarker using the Cat 966 front-end loader. This loader also took the debarked logs to
the woodroom for chipping. Since the bin debarker was a proto-type model, productivity data
was not recorded. After each diameter class was chipped, chip samples were collected from
different locations on the chip pile.
The green and burned logs to be debarked and chipped by the Peterson DDC5000 chain flail
debarker chipper were weighed and decked separately in the satellite yard. The Peterson
DDC5000 was moved to the decks and the chips were blown into a dump truck and weighed.
The total volume in each log class was manually scaled and debarking and chipping time for
each log class was determined.
As each log class was debarked and chipped, at least three 50-l plastic sample bags of chips
were collected periodically from the chip pile for analysis. The 50-l plastic sample bags were
sealed and sent to FERIC in Vancouver for analysis. When the chipping of each log class was
complete, a large tote bag was filled with 200 kg of chips for test screening. The tote bags
were sent to BM&M Machinery in Langley for screening through its test screen to remove bark
and charcoal.
4
Chips were analyzed for over thick, over sized, accept fines and pin chips using both a BM&M
vibratory classifier and a Domtar thickness classifier in accordance to Slave Lake Pulp’s chip
classifiation parameters (Appendix II). The moisture content of the chips was determined from
the unscreened chips taken for each test run.
Results
Table 1 illustrates the trials that are summarized in this study. The chip recovery and
productivity results of burned wood after one drying season were from an earlier study of char
removal using an optic vision sorter (Araki 1996). The Fuji/King debarker used in the first
year study was not available the second year so the proto-type bin debarker was used as a
replacement. No bin debarkers were available for the third year trials. There were several
difficulties with the flail debarkers so only second year trials were done.
Table 1. Summary of debarking and chipping studies of burned and green logs.
Drying Seasons After August 1998 Fire and Wood Condition During Debarking Debarker
1-nonfrozen 1-frozen 2-nonfrozen 2-frozen 3-nonfrozen Ring - Harvested - Debarked - Location - Study No.
July 1999 July 1999
Slave Lake R-NF-1
Feb. 1996a & 1999 Feb. 1996 a & 1999
Slave Lake R-F-1
Aug. 1999 Oct. 1999
Slave Lake R-NF-2
Nov. 1999 Mar. 2000 Slave Lake
R-F-2
Sept. 2000 Oct. 2000
Slave Lake F-NF-3
Bin - Harvested - Debarked - Location - Study No.
Feb. 1996 Feb. 1996 Slave Lake
B-F-1
Debarker not
available
Nov. 1999 Nov. 1999 Slave Lake
B-F-2
Debarker not
available
Flail - Harvested - Debarked - Location - Study No.
Aug. 1999 Oct. 1999 Fox Creek
F-NF-2
Nov. 1999 Mar. 2000 Fox Creek
F-F-2
Debarker not
available
a Data for this study was obtained from Araki 1999.
Since the ring debarker was able to fulfill the majority of the trials for the three years, the
weight ratios are compared from that data and illustrated in Table 2. The data for the weight
ratios of spruce was lost. No meaningful conclusions can be drawn from Table 2.
5
Appendix III summarizes the recoveries that were achieved in each of the trials. The chip
recoveries for the ring debarked logs were higher in some cases than those from the bin and
flail debarked logs for both aspen and conifers. The ring debarker operator adjusted the
pressure on the debarker arms to minimize fibre loss and improve the recovery results. The
flail operator could not adjust the speed of the logs through the flails because the chipper feed-
speed controlled the debarking speed. The drums of the flails could have been slowed down to
reduce fibre loss.
Table 2. Changes in weight to volume ratio.
First year Second year Species Log diameter
class Non-frozen (kg/m3)
Frozen (kg/m3)
Non-frozen (kg/m3)
Frozen (kg/m3)
Aspen Green - control 861 890 749 913
Burned <20a cm (dry) 622 681 558 899
Burned >20b cm (dry) 632 769 591 817
Spruce Green - control 650 747
Burned <25c cm 579 550
Burned >25d cm 851 480 511 a Butt diameters ranged between 16.5 and 20cm b Butt diameters ranged between 20.1 and 39 cm. c Butt diameters ranged between 16 and 25 cm. d Butt diameters ranged between 25.1 and 43 cm.
Appendix III also compares the productivities that were achieved by the debarkers over the two
years. The ring debarker had the highest productivity of the three debarking technologies. The
bin debarker had the lowest productivity because the bin debarker was a proto-type and more
modifications to improve debarking needed to be done. The ring debarker had a weighted-
average productivity of 82 m3/h over the two years while the bin had 20 m3/h and the flail 52
m3/h.
The productivity comparison between frozen and non-frozen log trials undertaken during the
second year of the study showed that the weighted-average productivity of the ring debarker
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declined slightly in frozen conditions from 111 m3/h to 99 m3/h. No operational changes were
made between processing green logs and processing the burned logs except changing the
debarker knife pressure on the log. Feed rates did not change therefore only the differences in
log size affected productivity.
The increase in productivity of the flail from non-frozen to frozen conditions was directly
attributed to the extra drum on the Peterson in the frozen log trial. In this study with limited
data, the three-drum flail almost doubled the weighted-average productivity from 40 m3/h to 69
m3/h. An earlier comparison of productivity between the 2-and 3-drum flails showed there was
an average increase of 13% when the extra drum was added (Araki 1996).
The moisture contents for the chips obtained from the logs sampled are summarized in Table 3.
Due to drought conditions that existed in 1997 and 1998 in the Slave Lake area, the chips from
green logs had lower moisture contents than normal. In this study, the moisture content of
aspen chips after two drying seasons had not reached the minimum moisture threshold of 30%
for the CTMP process. After the third drying season, their moisture content had reached the
minimum level. The moisture content of chips from three-year-old small diameter spruce is
probably in error. Chips from the large diameter burned conifers had an average 20% moisture
content and were drier than the minimum for all pulping processes.
Table 3. Summary of chip moisture contents after two drying seasons.
Species Log diameter class
1st year non-frozen
(%) Frozen
(%)
2nd year non-frozen
(%)
Frozen (%)
3rd year non-frozen
(%)
Aspen Green – control 43 range (42-46)
48 range(46-54)
50 range (42-56)
47 range (45-51)
50 range (47-52)
Burned <20 cm
41 range (37-46)
35 range (30-45)
29 range (26-34)
Burned >20 cm 39
range (34-52) 38
range (34-49) 41
range (31-47) 43
range (32-52) 32
range (29-36)
Spruce Green – control 39
range (34-46) 41
range (29-50) 48
range (47-52)
Burned <25 cm 18
range (15-21) 17
range (15-20) 25
range (24-25)
Burned >25 cm 22
range (16-30) 20
range (16-29) 20
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Appendix IV summarizes the classification of the chip samples produced from the debarking
trials. The percentage of pin chips and fines increased when processing the dry burned conifers
compared to processing green logs for both ring- and flail-debarked stems. The bin debarked
logs that were chipped in the ring debarker woodroom and the flail debarked stems produced
more pin chips and fines compared to ring-debarked stems. This was attributed to the rougher
surface left on the stems by flail and bin debarking action. The short lengths of the bin
debarked stems may also have contributed to an increase in pin chips and fines because short
and small-diameter stems cannot be firmly held and indexed to the chipper knives. The burned
logs also produced more pin chips and fines than green logs for all the debarkers.
Regardless of debarker, the bark content of the green logs was higher than that from burned
logs. In this study, the maximum bark content of the chips permitted was <1% in non-frozen
conditions and <2% in frozen conditions on a green-weight basis. None of the debarking
technologies processing green logs met the standard in summer conditions while most of the
chips produced in frozen conditions did make the minimum standard. Most of the chips
produced from burned and dried aspen logs did make the standard in non-frozen and frozen
conditions because the bark on many stems had fallen off or was easy to remove. This was
attributed to the deterioration of the bark-to-wood bond as the aspen stems aged. All of the
chips from burned spruce met the minimum bark standard except the third year ring trial.
The ring debarker had difficulty removing bark from the small-diameter stems regardless of the
log condition or age. The ring debarker was used to debark veneer logs to a 15-cm top
diameter and some of the burned logs had tops less than 15 cm in diameter.
The bark content of the chips from green logs and small diameter logs processed by the bin
debarked logs was too high for the pulp mill’s winter specifications.
In this study, the three-drum flail had more success in removing the bark from frozen logs.
Although this is a desirable result for bark content the quality of chips that were produced
indicated otherwise. The third drum on the flail debarker not only improved productivity but
also improved bark removal when compared to the two-drum model.
8
Charcoal was detected only in the chips from the first year frozen log trials. Some charcoal
dust was evident on the chips (not measurable) and some blackened bark was noted but no
burned fibre was found. This is a result of the changes in the harvesting and woodroom
procedures that occurred throughout the industry to address the salvage of the burned stems
(Dyson 1999a-g; Sambo 1998; Sauder 1997). The heavily charred logs were sorted out from
the other less burned logs or the heavily burned portions were bucked out of the logs before
delivery to the mills.
Screening
Table 4 summarizes the chips that were recovered from screening through the BM&M test
screens. Because the flail debarked chips had the highest percentage of fines and pin chips
more reject chips were screened out. It would appear that the aspen processed in the ring
debarker does not need to be screened as the pin chip and fines percentage were in the
acceptable range of <5%. The amount of reject chips was also very low. On the other hand,
the ring debarked spruce and all of the other trials benefited from screening as the proportion of
pin chips and fines were reduced to almost acceptable levels. The analysis of the chips
processed by the ring and flail debarkers and screened through the BM&M test screen showed
that the percentage of pin chips and fines from non-frozen burned spruce was still too high for
the pulpmill specifications (Tables 5 and 6). Screening of the chips from the three debarking
technologies in frozen conditions reduced the pin chips and fines percentages to acceptable
levels in all of the trials except the small diameter burned spruce. A slightly larger gauge
screen could reduce the fines and pin chips to an acceptable level.
After analyzing the unscreened chips produced by the ring debarker from all the three year old
non-frozen logs (Appendix IV), FERIC decided that screening the samples collected would be
unnecessary as the fines and pins percentages were within acceptable limits (except the
spruce >25 cm). The chipper did produce unacceptably high percentages of overthick and
oversized chips from the dry burned logs. No measureable char was recorded in any of the
samples although traces of char were detected in some samples.
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Table 4. Acceptable chips recovered from screening through BM&M test screen.
Non-frozen conditions Frozen conditions Debarker, species and log
diameter class Acceptablea
(%) Rejectsa
(%) Acceptablea
(%) Rejectsa
(%) Ring debarker Aspen – green 99.1 0.9 99.2 0.8 Aspen – burned <20 cm 98.7 1.3 99.5 0.5 Aspen – burned >20 cm 98.7 1.3 99.7 0.3
Green spruce 96.9 3.1 99.2 0.8 Spruce – burned <25 cm 97.8 2.2 97.5 2.5 Spruce – burned >25 cm 97.2 2.8 99.0 1.0
Bin debarker Aspen – green 96.7 3.3 Aspen – burned <20 cm 97.0 3.0 Aspen – burned >20 cm 98.9 1.1
Green spruce 97.4 2.6 Spruce – burned <25 cm 96.7 3.3 Spruce – burned >25 cm 94.2 5.8
Flail debarker Aspen – green 97.8 2.2 Sample only Aspen – burned <20 cm 96.4 3.6 97.7 2.3 Aspen – burned >20 cm 97.8 2.2 96.2 3.8
Spruce – green 95.8 4.2 Sample only Spruce – burned <25 cm 94.2 5.8 93.4 6.6 Spruce – burned >25 cm 95.4 4.6 95.3 4.7
a See Appendix I for definitions of chip classes.
10
Table 5. Screened chip analysis – non-frozen conditions.
Chip classa
Overs Accept Pin chips >10 mm >45 mm 13 mm 7 mm 2 mm Fines Bark Char Debarker, species and
log diameter class (%) (%) (%) (%) (%) (%) (%) (%)
Ring Aspen - green 6.1 1.1 78.9 9.7 1.1 1.0 .2 0.0 Aspen - burned <20 cm 7.9 0.6 64.8 20.8 2.1 2.2 1.6 0.0 Aspen - burned >20 cm 9.0 0.6 73.1 12.4 1.8 2.1 1.1 0.0
Spruce - green 11.3 0.3 68.3 14.5 2.0 2.2 1.4 0.0 Spruce - burned <25 cm 8.8 0.3 50.3 28.3 6.4 5.4 0.6 0.0 Spruce - burned >25 cm 12.8 0.1 47.3 28.4 6.4 4.5 0.4 0.0
Flail Aspen - green 7.9 1.1 62.9 22.6 2.0 2.5 0.9 0.0 Aspen - burned <20 cm 7.5 0.7 65.3 20.8 2.0 2.6 1.0 0.0 Aspen - burned >20 cm 10.9 1.3 68.3 15.6 1.5 1.7 0.7 0.0
Spruce - green 11.8 2.2 68.3 12.9 1.2 1.9 1.7 0.0 Spruce - burned <25 cm 5.8 0.5 50.7 30.6 5.2 7.0 0.2 0.0 Spruce - burned >25 cm 7.2 0.8 55.6 26.9 3.8 4.8 0.9 0.0
a % of chips classified that are retained on the indicated screen tray; see Appendix I for
definitions.
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Table 6. Screened chip analysis – frozen conditions.
Chip classa Overs Accept Pin chips >10 mm >45 mm 13 mm 7 mm 2 mm Fines Bark Char
(%) (%) (%) (%) (%) (%) (%) (%) Ring debarker Aspen – green 4.7 0.1 75.2 16.2 0.8 0.6 2.4 0.0
Aspen - burned <20 cm 6.3 2.0 79.6 10.1 0.6 0.6 0.8 0.0
Aspen - burned >20 cm 6.2 1.6 86.1 4.7 0.3 0.2 0.9 0.0
Spruce – green 22.7 0.6 56.3 16.0 1.1 0.8 2.5 0.0
Spruce - burned <25 cm 11.7 0.1 51.5 29.6 3.8 2.5 0.7 0.0
Spruce - burned >25 cm 17.7 0.1 50.6 26.7 3.0 1.6 0.2 0.0
Bin debarker
Aspen – green 1.5 0.3 80.7 12.2 0.5 0.6 4.2 0.0
Aspen - burned <20 cm 10.2 2.0 71.0 13.3 1.5 1.3 0.7 0.0
Aspen - burned >20 cm 8.7 2.2 83.3 4.4 0.6 0.4 0.5 0.0
Spruce – green 12.0 1.5 76.3 6.7 1.1 0.9 1.6 0.0
Spruce - burned <25 cm 5.4 0.4 52.2 34.4 3.9 3.2 0.5 0.0
Spruce - burned >25 cm 7.8 0.4 68.8 17.9 2.1 1.9 1.2 0.0
Flail debarker
Aspen – green 3.7 0.0 57.5 30.9 3.2 2.5 2.2 0.0
Aspen - burned <20 cm 13.5 0.2 58.6 20.8 2.8 2.7 1.3 0.0
Aspen - burned >20 cm 3.1 0.5 71.1 23.2 0.9 0.8 0.3 0.0
Spruce – green 2.2 0.8 80.1 12.6 0.5 0.7 3.0 0.0
Spruce - burned <25 cm 1.0 0.3 33.6 49.9 10.0 5.0 0.2 0.0
Spruce - burned >25 cm 1.7 0.2 46.9 42.5 4.5 4.1 0.1 0.0 a % of chips classified that are retained on the indicated screen tray; see Appendix I for
definitions.
Discussion
During harvesting of the three-year-old dry logs, more breakage was noted especially at the top
of the aspen trees. The contractor and company logging supervisors felt that it was becoming
too dangerous to operate in these stands unless every tree was felled before other equipment or
12
personnel entered the site. Because the dry wood was brittle, more breakage occurred
throughout all harvesting phases especially the smaller diameter stems. The brittleness of the
aspen made delimbing much easier than delimbing green logs. Three years after the fire bark
on aspen stems was beginning to fall off and there was little evidence of char on the stems.
However, the majority of the bark on the spruce logs was still firmly attached to the stem;
although some of the bark near the bases of the stems began to peel off when handled. It was
also noted that the log truck used to recover the sample could not load a full weight payload
before the log load reached the maximum load height.
Concern about destroying the newly established regeneration, which was approximately 1.5- 2
m in height, was expressed by a company supervisor. In this study, the aspen regeneration was
established during the summer of 1998 almost immediately after the fire and had three years of
growth. The supervisor felt the value of the newly established aspen stand far exceeded the
value of the chips that could be recovered. There was no evidence of any spruce regeneration
on the site. Even in winter conditions, the company supervisor felt the regeneration would
have been too tall to harvest the burned logs without causing extensive damage.
The target minimum moisture content for chips for all the pulping processes is 30%. This
study indicated that the larger diameter conifers might be still acceptable to salvage after two
years. The small diameter conifers were too dry for chips regardless of post-fire aging. The
larger-diameter aspen logs, on the other hand, were still useable after three years. When
harvesting burned wood, focussing on the smallest diameter stands first maybe a good strategy
as was done in Merritt, B.C. (Dyson 1999d). Operationally, big and small log sorts would be
useful; the small logs could be placed directly onto the infeed of the sawmill as they arrive, or
recovered from log storage on a first priority for use.
Although none of the chip samples showed any measurable charcoal in the unscreened chips
screening is probably effective in removing any trace amounts that may be present and that
may be difficult to accurately quantify. Chips produced from bin and flail debarked dry logs
should be screened to remove some of the fines and pin chips. The chipper in the pulp mill
produced too many oversized and overthick chips when processing the three year old dry logs.
13
This may have been related to the chipper anvil and knife settings on the disc that were set for
green logs and not changed when the dry logs were processed.
The high percentage of pin chips and fines produced by the flail and bin debarker from frozen
stems having two drying seasons (Table 6) suggests that the wood was too dry for aggressive
debarking. Similarly, the high percentage of spruce pin chips and fines from the ring debarker
also indicate that the maximum threshold of 5% was surpassed.
Conclusions
FERIC, with the assistance of Slave Lake Pulp, and Alberta Newsprint Company carried out a
study to determine the quality of conifer and aspen chips produced from burned timber that had
been left standing and dried for two and three years. These chips were compared to the chips
from green trees growing in the same area. The study logs were debarked using ring, flail, and
bin debarking technology.
The recovery of chips from burned aspen logs increased as the trees aged and was attributed to
the deterioration of the bond between the bark and the stem. This allowed debarking
equipment to remove the bark without damaging wood fibre and thereby increasing fibre
recovery. The larger diameter trees also had better chip recoveries than the small diameter
ones. The ring debarker generally had better chip recovery than the other two debarking
technologies because the operator had more control of the debarker when handling different
conditions and size of logs, and there was probably less fibre loss associated with debarking
action.
The productivity of the debarkers was not affected by age of the stems. No operational changes
occurred when the ring and flail debarkers were processing the different log trials. The ring
debarker processed 82 m3/h while the flail processed 52 m3/h. The limited data collected for
the bin debarker showed a 20-m3/h productivity.
After two years, chips from small diameter burned conifers had moisture contents of 15-21%
and were not desirable for pulping. The chips from large diameter conifers might still be
14
acceptable for CTMP pulping as their moisture was measured between 16-30%. Chips from all
of the aspen samples were still within acceptable moisture and size specification limits.
After three years, chips from large conifer chips were too dry and the chipper produced
unacceptable levels of over thick and oversized chips. Chips from all the aspen still had
moisture contents between 26-36% but also contained unacceptable levels of over-sized and
over-thick chips.
Harvesting of the aged stands was more difficult. More breakage, danger from snags, and
lower payloads resulted. One advantage that was noted was that delimbing of dry brittle aspen
was easier.
Regeneration considerations could limit the recovery of the burned aspen after three years. The
value of newly established natural aspen regeneration may exceed the value of the marginal
chips that were produced.
Although none of the chip samples showed any measurable charcoal in the unscreened chips,
screening is probably effective in removing any trace amounts that may be present and that
may be difficult to accurately quantify. There is, however, an advantage to screening the chips
to remove some of the fines and pin chips produced when chipping dry wood.
Implementation
In order to optimise the recovery of burned timber for chips, similar strategies to those used for
recovering logs for lumber should be initiated. The spruce should be harvested and utilized as
a first priority. If possible the small diameter spruce should be sorted and used before the large
diameter logs are processed. The aspen can be left and utilized later than the spruce. Again,
the smallest diameter aspen stems should be sorted out and processed on a priority basis as the
trees age.
Acknowledgements
FERIC wishes to thank the cooperators – Slave Lake Pulp Corporation and Alberta Newsprint
Company – whose assistance was invaluable in carrying out this project. Special thanks to
15
Allwood Chipping of Prince George, Jones Construction of Chilliwack, and BM&M
Machinery of Langley for the use of their equipment in debarking, chipping and screening the
study logs.
References
Araki D. 1996. Recovery of wood chips from low grade fibre sources. Forest Engineering
Research Institute of Canada, Vancouver B.C. FERIC Special Report SR-115. 23 p.
Araki, D. 1999. Recovery of pulp quality chips from burned stems. Forest Engineering
Research Institute of Canada, Vancouver BC. FERIC Special Report SR-130. 21 p.
Dyson, P. 1999a. Pulp quality chips from burned timber. Forest Engineering Research Institute
of Canada, Vancouver BC. FERIC Field Note Processing-FN-52. 2 p.
Dyson, P. 1999b. Debarking burned logs using the Deal processor. Forest Engineering
Research Institute of Canada, Vancouver BC. FERIC Field Note Processing-FN-53. 2 p.
Dyson, P. 1999c. Producing pulp quality chips from burned aspen. Forest Engineering
Research Institute of Canada, Vancouver BC. FERIC Field Note Processing-FN-54. 2 p.
Dyson, P. 1999d. Harvesting and milling burned timber in south-central B.C. Forest
Engineering Research Institute of Canada, Vancouver BC. FERIC Field Note Processing-
FN-55. 2 p.
Dyson, P. 1999e. Harvesting and processing burned timber in Alberta. Forest Engineering
Research Institute of Canada, Vancouver BC. FERIC Field Note Processing-FN-56. 2 p.
Dyson, P. 1999f. Grapple yarding burned timber in north-central Alberta. Forest Engineering
Research Institute of Canada, Vancouver BC. FERIC Field Note Processing-FN-57. 2 p.
Dyson, P. 1999g. In-woods processing of burned timber. Forest Engineering Research Institute
of Canada, Vancouver BC. FERIC Field Note Processing-FN-58. 2 p.
16
R.W. Nelson, J. Dobie, D.M. Wright. 1985. Conversion factors for the forest products industry
in western Canada. Forintek Canada Corp., Vancouver B.C. Forintek Special Publication No.
SP-24R. 92 p.
Sambo, S. 1998. Proceedings of a Workshop on Operational Solutions to Salvaging &
Processing Burned Timber, Whitecourt Alberta, June 1998. Forest Engineering Research
Institute of Canada, Vancouver BC. FERIC Special Report SR-127. 108 p.
Sauder, EA. 1997. Proceedings of a Workshop on a Salvaging and Processing Burned Timber,
Prince Albert, Saskatchewan, July 9-10, 1996. Forest Engineering Research Institute of
Canada, Vancouver BC. FERIC Special Report SR-124. 42 p.
Sauder, EA (compiler). 1999. Harvesting and processing burned timber in the Yukon:
workshop proceedings - held at Whitehorse, Yukon, October 19-21, 1998. Forest Engineering
Research Institute of Canada, Vancouver BC. FERIC Internal Report IR-1999-02-04. 51 p.
17
Appendix I
Literature Review of Harvesting Burned Timber November 2000
Introduction
As a parallel to the literature review done by Paprican (Watson and Potter, 1999) on the
pulping of burned timber, the Forest Engineering Research Institute of Canada (FERIC)
undertook a review of problems associated with harvesting burned wood. The harvesting and
utilization of the burned stands has been well documented by FERIC but the effects on
machines and workers is not well known nor has it been documented. In addition to the
literature review, FERIC had discussions with some equipment manufacturers, member
companies and logging contractors to determine the effects of charcoal on the equipment and
logging personnel.
Objectives
The objectives of the review were to identify and describe:
• equipment and engine wear (tribology) attributed to charcoal (soot);
• the effects of charcoal on forest and mill worker health;
• strategies that have been developed to minimize the detrimental effects of charcoal and
burned wood on lumber and pulp production.
Background
In 1998 wild fires destroyed thousands of hectares of forest in Alberta. The forest industry and
government have cooperated to salvage these burned stands. Information workshops, research
directed at burned wood and changes to Alberta forest regulations have provided the forest
industry with a better understanding of burned wood harvesting and utilization. FERIC, during
their ongoing discussions with the forest companies on the changes to the harvesting methods
and changes that occurred in the sawmills and pulpmill, attempted to see if charcoal had an
18
effect on equipment wear and forest- and mill-worker health. Much of the concerns expressed
were anecdotal and more information was needed.
Review
Three topic areas were investigated regarding burned wood: operational issues of harvesting
and milling; carbon tribology; and worker health concerns due to long term exposure to
charcoal dust and soot.
Harvesting and Milling
The majority of the information about harvesting burned timber was, and continues to be,
documented by FERIC. FERIC has held a total of four workshops in Alberta, Saskatchewan
and the Yukon since 1995 (Sambo 1998, Sauder 1996, 1997 and 1999). Other research papers
that were reviewed, focussed on the sawmilling of burned timber and did not indicate any
significant changes or problems in harvesting than those reported in the recent FERIC
publications. The only priority identified in the literature to minimize wood fibre losses
associated with salvaging burned timber was to harvest and utilize wood fibre as quickly as
possible before drying and checking occurred or, in the case of pine, before blue sap staining
degraded the value of the lumber (Gray and Pfitzer 1985).
The need for a cooperative approach to solving problems by both government and industry was
considered part of the Alberta Advantage (Sambo 1998). For their part the provincial
government relaxed the utilization standards to encourage harvesting of the burned stands and
reduced the stumpage on the burned timber to reflect the loss in lumber recovery and loss in
residual chip revenue. To take advantage of the economic incentives companies operating in
burned forests were required to submit salvage plans covering a two-year period to the
government by deadlines established within 6 weeks of fire containment. After the companies
had defined their salvage areas the government then had the option of allocating the excess
volume and area to other local forest companies or outside interests.
Speakers at the workshops FERIC organized identified the need for accurate information
regarding the area and location of timber burned, the amount of merchantable timber burned
19
and the degree to which the timber was burned when developing a timber salvage harvest plan
(Sauder 1996). Fixed wing colour photography taken from approximately 1500 m was
identified as a useful tool to identify and type burned stands and can be supplemented with
inventory maps and reconnaissance to develop initial salvage plans. This information needs to
be verified by ground checking prospective harvest sites to identify access routes and confirm
timber merchantability. Salvage plans also need to address issues regarding riparian zones and
water quality so that harvesting operations do not induce additional disturbance of these
features.
The danger of blowdown of burned timber in spruce and mixed spruce-aspen stands is major
safety concern that must be addressed in early planning. Trees in spruce and mixed spruce-
aspen stands are susceptible to blowdown because the deep organic layers associated with these
timber types can provide sufficient fuel to burn away the shallow supporting roots of the trees
(Dyson 1999d). As a result of the danger to forest workers from the unsupported trees, forest
operations in standing timber should be mechanized. Pure aspen stands rarely have enough
organic debris in or on the soil to sustain a deep burning ground fire.
Windthrow potential after a fire is also a major consideration as the harvesting equipment and
timing of salvage may have to be changed or modified. Stands immediately after a fire may not
show any blowdown. However, as time progresses trees may blow down and become a major
obstacle to conventional harvesting equipment. In areas of blowdown, mechanical feller-
bunchers with tilting heads or dangle head feller-processors can be used to salvage the timber
and log loaders equipped with bucking saws are another option (Sauder 1996). In areas where
manual falling is the only option, harvesting should be delayed until winter where a snow
covering and frozen ground might minimize the blowdown potential. Another minimum
precaution during manually falling is to only work when there is no wind.
Fire damaged timber is subject to drying and reductions in wood moisture can effect the
amount and quality of wood products recovered. In cases where the salvage operations extend
over more than one year of operation, the order of salvaging might have to be altered to
minimize fibre loss due to drying (Dyson 1999c). One strategy used by a BC interior company
was to recover the smaller butt-diameter stands before the larger stems were salvaged out of
20
concern for the amount of drying and wood checking that would occur if the smaller stems
were not recovered within the first year (Dyson 1999d).
Generally, the harvesting equipment or system used to recover burned timber has not
significantly changed except in the environmentally sensitive areas (Dyson 1999f). One
company contracted a grapple yarder to remove burned trees from steep slopes and from wet
areas. The yarder enabled the company to also harvest sites that normally would have been
only accessible during the winter. The companies that have cut-to-length harvesting systems
have increased their yearly quotas and in some cases new contractors have been hired to
process stems at the stump or roadside into shorter log lengths to minimize the amount of
charred material being delivered to the sawmills (Dyson, 1999g).
The most frequent concern identified in the literature, workshops and during site visits for the
sawmills utilizing burned timber is the potential loss of revenue due to the presence of charcoal
in their residual chips (Sauder 1996 and 1997, Sambo 1998, Dyson 1999a, Watson 1999).
Traditionally pulpmills have refused to accept any charcoal-contaminated chips because of the
potential impact of charcoal particles on pulp quality and the subsequent impact on markets.
Early utilization of burned timber dismissed any notion of recovering chips from burned timber
and focussed only on utilizing recovered burned fibre for lumber production mainly because
alternative sources of non-burned timber were readily available (Gray 1985). However, today
with fibre resources nearly fully allocated there is insufficient non-burned fibre available to
replace the burned timber and pulp producing companies are investigating the use of chips from
burned timber provided the chips meet their quality control parameters. Government directives
and economic incentives that direct companies to utilize burned timber resources before green
timber further emphasis the need for pulp companies to investigate strategies to ensure charcoal
is not present in pulp chip furnishes recovered from burned timber (Sauder 1996).
It was initially proposed that logs recovered from burned stands be sorted into burned classes to
minimize charcoal contamination of residue pulp chips (Sauder 1996). One of the first
operational strategies utilized by harvesting operations to minimize charcoal contamination of
21
pulp chips was to sort the timber recovered from burned stands and process the stems into logs
of varying degrees of burn. Logs that were heavily burned were traded to sawmills where the
chips could be wasted (Sauder 1996, Dyson 1999a). Pulp chips from logs that exhibited light-
and medium-degrees of burn damage could be recovered provided debarking was aggressive
enough to remove any attached charcoal. This initial procedure worked but when it became
evident that too much valuable volume was being lost, the heavily burned logs were sent to the
sawmills, cut into lumber separately, and the residual chips wasted. Sorting was done at the
stump by the feller-buncher and/or at roadside by the log processor where the charred portions
of the log were cut out. These logs were sent to the sawmills separately, and stockpiled for
batch cutting into lumber. The remaining burned timber (light and medium) has been
processed without significant operational changes. The pressure on the debarking arms of the
ring debarkers was increased to pressures similar to winter debarking conditions and/or the feed
speed through the debarkers was reduced to ensure complete debarking. In some sawmills,
winter debarking knife tips were used.
There was an increase in cost associated with harvesting burned timber (Sauder 1996, 1997). It
was estimated that there would be a 10-15% productivity loss because of the amount of sorting
that was done at each phase of harvesting. Only the skidding costs were determined not to have
changed. Feller bunchers sorted stems at the stump; log processors working at roadside sorted
burned and non-burned stems and bucked out burn defects; and finally, log loaders did not load
stems with char on log trucks. Because sorting is a visual estimation of degree of burn into the
wood fibre accurate sorting at night is difficult. Hiring an extra log processor and operating in
daylight hours is an option that should be considered. Extra lighting on the machinery might
assist in better sorting.
Extra maintenance costs needed to be recognized. Discussions with the logging contractors
revealed that maintenance time and cost were doubled. Immediately after the fires, equipment
working in burned areas had complete oil changes after only 100 h of operation and air filters
were often changed twice a day. As the amount of charcoal diminished over time, the
maintenance schedules were adjusted accordingly. The equipment manufacturers still
22
recommended that oil and filter changes be done after 150 h of operation even in the second
year of salvaging.
Depending on accessibility, extra allowances had to be made for hauling on freshly built roads.
Similarly, allowances were made for harvesting burned and blown down stands on a site by site
evaluation.
The only concern expressed by the sawmill personnel was the spiked rolls on some processors
pushing charcoal into the wood fibre beyond the debarking knife penetration especially on thin
bark species such as spruce (Araki 1999).
Some lumber sales required no colour blemishes on any of the lumber surfaces and staining in
these depressions by charcoal and bacterial organisms (blue stain) was identified as a major
concern. In fact, most of the burned logs were not used for export lumber production.
Maintaining accurate length measuring was another concern especially when cut-to-length
harvesting was done. The photo cells of the measuring systems have to be kept clean and since
carbon is a conductor the connections and computer had to be free of charcoal at all times.
More frequent checking of lengths needed to be done.
Many of the companies in Alberta upgraded their sawmills to handle the sudden increase in
available timber. Many installed extra-ring debarkers and/or replaced old single ring debarkers
with new double ring debarkers to improve debarking capability and throughput (Dyson
1999e). Logs that still had charred material on the bole after debarking were removed from the
mill infeed deck and directed back to the infeed of the debarker for reprocessing. The mills
were encouraged to replace the punched plate fines screens with the more aggressive woven-
wire mesh screens. Although more fines and pin chips were wasted, the remaining accept chips
were char free. With the improvements to the sawmills, the sorting of the burned material
during harvesting by some companies was discontinued as it was deemed unnecessary. One
pulpmill installed a high-pressure water spray system behind the debarker to remove any
charcoal prior to chipping (Dyson 1999c).
23
Discussions with all the mills utilizing the burned timber indicated that the lumber recovery
was reduced slightly due to aggressive debarking but the increase in throughput more than
compensated for the recovery reductions. All of the mills increased their lumber production to
all time highs by adding extra shifts and/or working seven days a week. This insured the logs
were processed into lumber under optimum sawing conditions. The main concern about
charcoal in the chips was quickly solved with immediate implementation of log sorting, extra
debarking and new ‘fines’ screens. The sawmills focus now appears to be losses in recovery as
the logs dry and excessive checking occurs. A more noticeable result of the utilization burned
logs was the sudden excess supply of chips that effectively reduced their value. This was the
main reason for the reluctance of the pulpmills to purchase the chips early in the salvage
program. The personnel of CTMP mills indicated that moisture content of the chips would be
the major concern as the burned wood got older.
Carbon tribology
Wear on external machine parts FERIC was unable to find any published information on the effects of char or soot on external
machines parts. Discussions with other research organizations indicated that carbon alone
would have little effect on the exposed moving parts of machinery as the particulate would be
too small and that dirt and sand would be far more abrasive than soot. Logging contractors
indicated that wearing of parts did appear to occur in the first year of harvesting after a fire
while the problem did not appear to exist in the second year. This phenomenon is probably a
result of machinery working on exposed soils in the first year where all of the organic layers
were burned and the charcoal mixed with the mineral soil and could have caused accelerated
wear on some of the moving parts of the logging equipment. By the second year, the rain,
snow and wind would have removed most of the fine loose charcoal from the trees and the
burned sites would have reestablished a herbaceous cover and reduced direct soil contact with
metal parts. In any event, machine wear as a result of harvesting burned timber is very difficult
to identify or quantify. As a precaution, the contractors increased the frequency of machine
maintenance to ensure the moving parts were cleaned and well greased. In the sawmills where
24
continuous processing of burned logs occurred, no excessive wearing was reported which
reinforces the theory that it is the sand and dirt that is the problem. As a precaution, the
maintenance of the machinery around the mill infeeds and the debarkers has been increased.
Engine wear Engine wear, on the other hand, has been studied and well documented (Bardasz et al 1997,
Gautam et al 1998, 1999). The majority of logging equipment in western Canada uses diesel
motors because they have better fuel economy. Diesel motors, unfortunately, have high levels
of exhaust and particulate emissions (soot). Under normal operating conditions, engine oils
and their additives prevent wear by coating the metal on metal surfaces with an antiwear film
and disperse soot evenly through the engine oil. Developing different formulations of oil and
additives to protect the engine parts for extended periods in different operating conditions has
been an ongoing challenge to manufacturers. Mechanical damage of engine surfaces include
abrasion, adhesion and fatigue while corrosion and lubricant breakdown contribute to
chemicals reactions that ultimately results in engine wear. Diesel soot is produced in the
engines and reduces the lubricating properties of the engine oil and causes some abrasion and
wear of the engine. Some research indicated that small soot particles less than 0.02µm did not
affect antiwear properties while soot particles greater than 0.03µm may be one of the dominant
factors in increased wear. Instead of coating the engine walls with antiwear film the oil adheres
to the large soot particles and unlike small soot particles are not easily dispersed through the
engine oil. Left unchecked, this would lead to accelerated engine wear. It is not unreasonable
to conclude that the addition of charcoal soot from burned trees into the engines would have
similar effects of having excessive amounts of large diesel soot particles and lead to an
accelerated breakdown of the oils lubricating ability.
In order to minimize the amount of soot entering into the motors through the carburetors, the
air filters were replaced daily and often twice a day when working in heavily burned stands.
The manufacturers of the logging equipment recommended that the oil and oil filters should be
changed after 100-150 hours of operation. The frequency of accelerated maintenance was
reduced, as the amount of airborne charcoal became less. In the second season after a fire,
25
most of the trees did not have much airborne charcoal and the contractors returned to more
normal maintenance schedules.
Health effects of soot
The Alberta Occupational Health & Safety treats charcoal dust as a carcinogen (Sauder 1996,
Sambo 1998). The regulation states that human exposure to air borne particulate of non-
allergenic wood dust must be less than 5 mg/m3 if the exposure is continuous for 8 hours or
10mg/m3 if the exposure is of limited exposure of 15 minutes in duration (Province of Alberta
1984).
Soots are lustreless black substances, which can be defined as the by-product of any incomplete
combustion or pyrolysis of any kind of carbon containing material (IARC 1985). Any carbon
containing material may undergo incomplete combustion and give rise to the formation of soot
as an unwanted by-product. The exact composition of soot is dependent on the material being
burned and the combustion conditions that existed when the soot was formed. In the case of
forest fires, it would be reasonable to expect that different soot is produced from the burning of
conifers, hardwoods and ground fauna. In this review, all the discussion will centre on wood
soot as the majority of the exposure of workers would be to soot from burned trees.
The effects of occupational exposure to soot on humans have also been well documented
(IARC 1985). The earliest recorded incidence of the effects of soot was on the health of
chimney sweeps in the 1700’s. The incidences of skin cancer especially cancer of the scrotum
commonly called “soot-warts” was prevalent amongst the men who cleaned chimneys. Later
studies during the 1920’s found that the coal soot and not wood soot contributed to the highest
rate of skin cancer. Studies in the 1940’s did show that an ethanolic extract of eucalyptus wood
soot applied to the skin of female mice (10) all developed cataracts. Scientific studies on mice
and rats during the 1980’s confirmed that coal and oil soot was carcinogenic when it was
applied to the skin. No incidences of skin cancer on mice from exposure to wood soot was
found. When wood soot was implanted under the right axilla (cavity under front leg and body),
urinary bladder sarcomas (malignant growth) on some of the female mice (2 of 10) developed.
One developed bladder carcinoma while the control mice (20) had none. The conclusion
26
reiterated that the samples in these studies were too small and larger testing was needed. Many
of the studies done in the 90’s have focussed on the effects of carbon blacks not normally
associated with charcoal from wood.
The incidences of lung and larynx cancer was found to be higher amongst people who worked
as chimney sweeps in the early 1900’s but the studies did not differentiate between soot from
coal or wood. A study on 74 mice which were divided into groups of 8-10 mice and subjected
to a moderate cloud of soot once an hour for six hours, five days a week for a year developed 8
benign and 4 malignant tumors (total 16%). This was not significantly different than those in
the six control groups that had lung tumor incidences between 8-20%.
Since soot from burned forests has not been analyzed, workers as part of the normal safety
procedures should be encouraged to minimize their exposure to soot. In the sawmills, where
continuous exposure to soot was most obvious extra precautions were taken. The infeeds to the
mill and the debarker areas had to be isolated as much as possible to minimize the amount of
charcoal dust from entering into the mill. Temporary (tarps) and permanent walls were
constructed and/or fans and vacuums were installed around the debarkers by some mills.
Others put the debarkers outside the mill while some mills installed water spray systems for
summer operation only (Dyson 1999e). Men working near the debarkers were required to use
mouth and nose masks to filter the air. They were also encouraged to wear coveralls when
servicing machinery and wash soot off the skin as soon as possible after exposure. Cleaning
the soot off machinery by washing or careful dusting before servicing is also recommended.
However, air pressure should not be used to blow particulate containing soot off machinery.
More monitoring of the air quality within the mills was recommended. The debarking areas
should be cleaned more frequently to minimize the soot buildup.
In the harvesting area, air borne particulate was not a major concern as harvesting occurs
outdoors in a unconstrained environment and the majority of workers working directly in the
burned stands were seated in air conditioned and heated cabs where charcoal dust could be kept
out. The air filters in the cooling and heating systems needed to be changed periodically.
When servicing or repairing the machinery, the work area should be cleaned as best a possible
using air or water spray.
27
Conclusions
The harvesting and utilization of burned timber in Alberta has been very successful as the
government and the industry has cooperatively developed a strategy that ensures that the
majority of the useable timber is salvaged.
Research that has been directed at developing strategies to reduce charcoal in the residual chips
has minimized the amount of fibre that is wasted. Companies have developed harvesting
strategies to separate the heavily burned material from the logs and process them separately.
Sawmills have installed double ring debarkers to remove the charcoal. The government has
reduced the stumpage to reflect the losses in lumber recovery and residual chips.
The only problems associated with harvesting have been the extra maintenance required to
keep the engines clean of charcoal and soot as they might lead to premature engine wear. Extra
greasing of harvesting equipment along with frequent air filter changes is recommended. Some
extra costs in processing, sorting and maintenance have been recognized by industry.
The health and safety concerns surrounding air particulate is not an issue in harvesting sites but
workers should have protective clothing (coveralls) and a means of washing off the charcoal
after working around dirty equipment as the Alberta Occupational Health and Safety
regulations considers wood dust and charcoal carcinogenic.
28
References
Province of Alberta. 1984. Occupational Health and Safety Act. Ventilation and Chemical
Regulations. Alberta regulation 326/84. pp 1-4 and 57.
Araki, D. 1999. Recovery of pulp quality chips from burned stems. Forest Engineering
Research Institute of Canada, Vancouver BC. FERIC Special Report SR-130. 21 p.
Bardasz, Ewa A, Carrick, Virginia A, George, Herman F, Graf, Michelle M, Kornbrekke,
Ralph E, Pocinki, Sara B. 1997. Understanding Soot Mediated Oil Thickening Through
Designed Experimentation – Part 5: Knowledge Enhancement in the GM 6.5L. Conference
Presentation and Proceedings of the 1997 Society of Automotive Engineers Meeting.
pp 126-40
Dyson, P. 1999a. Pulp quality chips from burned timber. Forest Engineering Research
Institute of Canada, Vancouver BC. FERIC Field Note Processing-FN-052. 2 p.
Dyson, P. 1999b. Debarking burned logs using the Deal processor. Forest Engineering
Research Institute of Canada, Vancouver BC. FERIC Field Note Processing-FN-053. 2 p.
Dyson, P. 1999c. Producing pulp quality chips from burned aspen. Forest Engineering
Research Institute of Canada, Vancouver BC. FERIC Field Note Processing-FN-054. 2 p.
Dyson, P. 1999d. Harvesting and milling burned timber in south-central B.C. Forest
Engineering Research Institute of Canada, Vancouver BC. FERIC Field Note Processing-FN-
055. 2 p.
Dyson, P. 1999e. Harvesting and processing burned timber in Alberta. Forest Engineering
Research Institute of Canada, Vancouver BC. FERIC Field Note Processing-FN-000056. 2 p.
Dyson, P. 1999f. Grapple yarding burned timber in north-central Alberta. Forest Engineering
Research Institute of Canada, Vancouver BC. FERIC Field Note Processing-FN-057. 2 p.
Dyson, P. 1999g. In-woods processing of burned timber. Vancouver, BC. Forest
Engineering Research Institute of Canada, Vancouver BC. FERIC Field Note Processing-FN-
058. 2 p.
29
Gautam M, Durbha M, Chitoor K, Jaraiedi M, and Mariwalla N. 1998. Contribution of soot
contaminated oils to wear. Conference presentation and Proceedings of the 1998 Society of
Automotive Engineers Spring Meeting. pp 55-77.
Gautam M, Chitoor K, Balla S. 1999. Contribution of soot contaminated oils to wear-Part II.
Conference presentation and Proceedings of the 1999 Society of Automotive Engineers
Meeting. pp 47-67
A.H.Gray and R.H. Pfitzer. 1985. Log salvage and storage operations following the Ash
Wednesday bushfires in the South East of South Australia. ANZIF Conference presentation
published in Australian Forestry 1985.48 (3). pp 182-192.
IARC. 1985. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to
Humans. Vol 35. Polynuclear Aromatic Compounds, Part 4, Bitumens, Coal-Tars and Derived
Products, Shale-Oils and Soot. pp 219-241
Sambo, S. (editor). 1998. Operational Solutions to Salvaging & Processing Burned Timber;
Proceedings of a Workshop held June 18, 1998. Forest Engineering Research Institute of
Canada, Vancouver BC. FERIC Special Report SR-127. 108 p.
Sauder, E.A. (editor) 1996. Salvaging and Processing Burned Timber; workshop proceedings
High Level, Alberta, November 13-14, 1995. Forest Engineering Research Institute of Canada,
Vancouver BC. FERIC Internal Report. 102 p.
Sauder, E.A. 1997. Proceedings of a Workshop on a Salvaging and Processing Burned
Timber, Prince Albert, Saskatchewan, July 9-10, 1996. Forest Engineering Research Institute
of Canada, Vancouver BC. FERIC Special Report SR-000124. 42 p.
Sauder, EA (editor) 1999. Harvesting and Processing Burned Timber in the Yukon: Workshop
Proceedings - held at Whitehorse, Yukon, October 19-21, 1998. Forest Engineering Research
Institute of Canada, Vancouver BC. FERIC Internal Report IR-1999-02-04. 51 p.
Watson, Paul and Potter, Simon. 1999. Burned wood in the pulp and paper industry: a
literature review. Pulp and Paper Research Institute of Canada, Vancouver BC. Paprican
Miscellaneous Report MR 411. 12 p.
30
Appendix II
1. Chip classification
Over thick – chips that are over 10 mm in thickness
Over sized – chips that are over 45 mm in size
2. The percentage of over thick and over sized chips is not to exceed 10%.
• Accept chips – those chips that were between 3 mm and 10 mm in thickness and
between 7 mm and 45 mm in size.
• Pin chips – those chips that were smaller 7 mm in size and greater than 2 mm in
thickness
• Fines – those chips that were smaller than 7 mm in size and less than 2 mm in
thickness.
3. The percentage of pin chips and fines is not to exceed 5%.
• The bark content on a wet basis is not to exceed 1% in warm weather conditions and
1.5% in winter.
31