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.

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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.

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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.

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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.

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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

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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