North Central Forest Experiment Station

John H. Ohman, Director

Forest Service -- U. S. Department of Agriculture

1992 Folwell Avenue

• St. Paul, Minnesota 55108

Manuscript approved for publication May 12, 1977

1977
CONTENTS

Page

Study Methods.................................................... 1 ..

Amounts and Kinds of Residue ..................................... 2

Disposal .......................................................... 3

Trends ........................................................... 4

Potential Uses . •.................................................. 4

Summary ......................................................... 5

Literature Cited ..' ............................................... 6
SECONDARY WOOD RESIDUE: PRODUCTION, USE,

AND POTENTIAL IN THE TWINCITY AREA

• .

Eugene M. Carpenter, Market Analyst

Duluth, Minnesota

..

Manufacturing wood products from lumber, Information was requested on volume by species

plywood, and particleboard inevitably produces and kind of residue, moisture content, contaminasawdust, shaongs, and trim. Much of this waste tion, methods of disposal with resulting income

materia! is discarded, and little has been done to and/or costs incurred, and anticipated changes in

investigate potential salvage opportunities. Salvage any of these factors in the near future. Firms

of this waste material could augment the supply of producing a ton or more of wood residues a week

wood fiber, .alleviate the environmental impact and were visited in person. At that time samples of the

reduce the cost of solid waste disposal, and help coarse and fine residues were obtained where

overcome the energy crisis, possible. Fine residue is sawdust, shavings, sander

dust, and router chips; coarse residue is the solid

To get a better understanding of the wood waste trim from lumber, plywood, and particleboard.

problem :and the salvage potential we set out to

investigate the amounts and kinds of wood residue

developed by secondary wood product manufacturers ---

in a selected metropolitan manufacturing area, to

determine what disposal was made of the material, _.,,_o_ /

and to identify physical characteristics, location, \ I

costs, and potential markets. /__ go_a _,o_ _ /

/ r----_--V.... -7.... I/

STUDY METHODS _ : _ | _"'w""_

• I

The Area -_ l "'""""°"'_ l l\

I L, St.Pau, I I I

l "ENNEPIN [ _ _ I ' /

met o o i The Study encompassed the Minneapolis-St. Paul _ : ,,_ x_J [ /i.c u e ounties of / i I

" Anoka,. Dakota, H-ennepin, Ramsey, and ......... J [

Washington (fig. D. Although this area is approximately 50 miles wide by 60 miles long, the bulk of ]k

•theresidue produced is within a 20-by-30-mile area i ,0,_ _J

in Hennepin, Ramsey, Washington, and northern • ,_.o,_,,.,,u. I ' I

Dakota Counties ..... ,,,,ion 1 [..._j I

• DAKOTA Data Collection

Data .from firms generating less than 1 ton of Figure 1..-MapofMinneapolis-St. Paul, the

wood residue per week were collected by telephone. Study Area.
Residue estimates were collected from 91 firms in amount generated. All indicated that none of their

selectedStandard Industrial Classes (SIC)that are residue would be available for another use. We

considered secondary wood product manufacturers: estimated that these firms generated about 9,500

tons annually, but these data are not included in the

Number following analysis.

of

Product Description SIC Plants

Hardwood dimension and flooring 2426 6 Fine Residue

MiUworkand related products 243 54

Wood containers and pallets 244 9 Forty-two firms generated 12,785 tons of fine

Miscellaneous wood products 249 5 residues annually. These fine residues were kept

Furniture 251 3 separate from other residues and trash. Twenty of

Fixtures 254 14 the 42 firms produced 50 tons or more annually and

, 91 accounted for 98 percent of the total amount of fine

residue produced.

The samples of fine residue were evaluated by

placing the material in a drum with a perforated, We classified the freematerial as hardwood or softweighted, floating lid. The drum was dropped and wood based on botanical origin, that is, from

shaken:to simulate the compaction that might be broadleafed trees or conifers, and not on the density

of the wood, and as shavings, sawdust, or a mixture achieved by treading the material while loading a

of the two. truck. One cubic foot of the compacted material was

weighed, placed in a moistureproof bag, and taken

to the laboratory for screen analysis and moisture Of the 12,785 tons of fine residue, 80 percent is

hardwood sawdust or shavings, nearly all mixed content determination. The fine residues were

screened through a Williams Standard Pulp Testing together by 16 finns. Two finns have small amounts

-Apparatus with six 24-inch square trays. After of hardwood shavings, and three firms have small

being shaken for 5 minutes the trays were weighed, amounts of hardwood sawdust. The remaining 20

then shaken for another minute, and reweighed, percent is a conglomerate of hardwood and softwood

Only minor changes were recorded from the sawdust and shavings mixed together, produced by

additional _ shaking. Sieve sizes were 1 inch, 1/2 19 firms.

inch, 1/4 inch, 1/8 inch, 1/16 inch, 1/32 inch, and

dustpan. The weight of mixed shavings and sawdust ranged

from 6.0 to 17.5 pounds per cubic foot as collected,

and 5.4 to 16.2 pounds per cubic foot ovendry An estimate was made of the size of the coarse

residue pieces, and samples were bagged for moisture (table 1). Sawdust ranged from 14.1 to 15.4 pounds

content determination. Moisture contents are green, and 8.8 to 14.0 pounds ovendry. Green

reported on a green basis for both fine and coarse shavings weights were 4.5 to 16.6 pounds, ovendry

residues. _ were 3.8 to 7.9 pounds.

About two-thirds of the fine residue had a

• AMOUNTS A'ND KINDS moisture content of 10 percent or less, and 22

OF RESIDUE Table 1-Average weight and size characteristics for

fine residue samples

About 32,000 tons of residue were generated in

1974 by all secondary wood product manufacturers Kind of.. : : Weight per : Size of material l

in the studyarea. Of this, 10,295 tons were used for material: Samples : cubicfoot :

: : Green : Dry : <1/8 inch : 1/8 inch+

fuel, i0,101 tons were dumped or given away, and __ . Po_d, .... P_o_t - - -

11,836 tonswere sold. ' Ssawhavidngsustand 12 12. I i0.5 68 32

Sawdus I: 3 14.7 I0.0 99 I

Shavings 2 I0.5 5.8 17 83

Fivemillworkfirmsburned theirresiduefor 's..ptpe_rcents were weighted by annuavlolumi:eo derive

plant or process heat and hence did not estimate the table value.

2

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percent was from 10 to 25 percent. Only 13 percent areas up to 200 square inches; they were in every

had a moisture content between 40 and 55 percent, imaginable configuration.

green basis. The wettest material came from wood

container and pallet firms. More than 70 percent of the coarse residue had a

moisture content less than 15 percent; a small

Nearly all the mixed samples, passed through the amount was in the 20-percent range, and about onel/2-inch screen, and none had as much as 1 percent quarter was in the 50-percent range.

of material 1 inch or larger. Less than 2 percent of

•the shavings samples stayed on the 1-inch screen. Contamination was minor for coarse residue. The

firms who mixed their residue with other trash said

Contamination was not a problem in the fine foreign materials could easily be kept separate if

residues, markets were found for the wood portion. Occasionally

paint or other finishes were found, but the most

Coarse Residue • serious contaminants were vinyl overlays or high

density laminates. However, these were extremely

Seventy:one "firms generated 9,947 tons of coarse rare.

wood residues in 1974. Twenty-eight of these firms

produced more than50 tons annually; the top five DISPOSAL

yielded slightly more than half the total amount.

Mixtures of fine and.coarse residues were classed as Fine Residues

coarse. Only small amounts Offines were included

• in thesemixtures. Most of the coarse residue is Most of the fine residues were used. Eleven firms

either hardwood lumber trim or a mixture of reported dumping the material, but they accounted

lumber, plywood and/or particleboard (table 2). A for less than 1 percent of the total volume. Four

small amount of hardboardis included in the mixed percent of the total was used for plant fuel by two

categories, firms.

Trimmed blocks; strips, and edgings of lumber, Seventy-six percent of the fines were sold and 19

plywood, and particleboard from 1/2-by 1/2-to 4- percent were given away, mostly for animal or 

by-6-inch widths in lengths of 1/2 inch to 16 feet poultry bedding. At least four sawdust andshavings

were discarded. The wider lumber waste is dealers operate in the study area, but several firms

generally less than 3 feet long with 6 to 10 inches dealt directly with local farmers.

common. Most of the longer material is less than 8

feet long, mostly thin strips. Occasional pieces of The market was generally unorganized. Price was

plywood or particleboard were found with stu'face negotiated on an individual basis, and depended

somewhaton dryness,volume,andloadinfgacilities.

Pricesrepo_ rangedfrom$0.22to$2.86a cubic

Table2_Distributiofoncoarseresidueby species yard,with$0.75an approximateaverageThos . e

' and kind of material firms giving away their fine residues seemed

satisfied to have the material removed regularly at

• Kind of material" :

:_of

Num

firms ber ::

Tons :

:

Percent nocost.

Lumber--Hardwood " 13 4417 44

Lumber--Hardwood and

• softwood mixed 3 1341 13

Plywood--Haranddwood Coarse Residues

softwood 'mixed i 17 (1)

Par tlcleboard--Hardwood

andsoftwoomixd ed 2 142 I Disposaoflcoarsreesiduewassgenerallya problem. 2

Mixedsolid_--Hardwood Sixty-thrpeeercentwasdumped orburnedaswaste and softwood mixed 27 3282 33

Allmlxed3--Hardwood and by 62firmsMo. stfirmscontractetodhavematerial

softwoodmixed 25 748 S hauled away; a few used their own trucks. Thirteen 

l Insignificant amount, percent was given away for fire wood or youth

2M±xture of lumber, plywood, and/or part:icleboard, group woodworking projects. Two percent was used

31nclu.bot deshfineandcoarse residues, forplantor processheatby threefirms,and 22

3
percent was S01d to Charcoal manufacturing plants although the market in the study area is presently

by two firms, somewhat unstructured, demand is strong and will

" compete with any attempt to divert material to

Annual disposal costs reported ranged from zero other uses.

to $9,000, with a dozen firms indicating annual

expenses of more than $1,000. Costs averagedabout Minnesota's status as a leading producer of

$2.25 per cubic yard. Many of these firms had turkeys creates a market for 5 to 6 million cubic feet

investigated alternative disposal methods including of loose litter annually. In addition, the broiler

chipping and fuel. However, investment require- chicken industry requires about a million cubic feet.

ments were too high to justify ins_!!ing necessary Bark-free, dry shavings are preferred for this use.

process'rag equipment for the _mount of residue An attempt by a local processing firm to convert

generated, coarse lumber trim to shavings for animal bedding

was unsuccessful.

Although almost all firms would welcome an

alternati,¢e to dumping the residue, surprisingly Specialty markets for pet and laboratory animal

few considered disposal to be a big problem. Many bedding exist. These products command relatively

firmsthat paid several hundred dollars per year for high prices, but require special processing,

disposal probably did not consider this an exorbitant including sterilization. .

amount relative to their costs of doing business. The manufacture of wood flour from dry wood

residue is described by Reineke (1966). Primary

TRENDS uses are in the manufacture of linoleum, explosives,

and plastics. Total consumption is not large, and

Most of the 91 firms interviewed indicated they consumer requirements are rather exacting.

did not expect any significant change over the

•next 3 years in the amotmt or kind of residue The manufacture of floor sweeping compounds

'produced. Three firms had definite expansion plans from dry sawdust is usually a sideline for firms

and esl_imated a doubling of residue production. A: engaged in other wood processing activity or by

few firms commented that their business activity small specialty firms with local or regional distribution CLTSDA1966). Was slightly depressed and they would expect

moderate increases only if the economy improved. The coarse material has poor potential for use as a

A few others expressed the contrary view that pulp furnish because of the low moisture content,

business was good during the study period. Thus, mixture of species, and the problem of developing a

there was no consensus to suggest residue volumes suitable pulp chip from the conglomerate of trim.

were adversely influenced by the state of the One exception might be as a furnish for the.less

economy for the groups studied, particular roofing-felt market. Some of the fine

material has been used for this product.

None of the firms expected to substitute other

.materials for the wood components in their products Both fine and coarse residue can be used for

or processes. Also, none indicated they planned to particieboard manufacture because dry material

• change the methods they were using. For example, is usually preferred. However, no local market

none planned to increase" the use of cut-to-size or exists, and the supply is too limited, to support

prefinished parts, which might shift residue ac-

• an efficient particleboard mill. Transportacumulation outside the study area. tion costs prevent the shipment of all but the

highest quality dry shavings to regionalparticleboard

POTENTIAL USES markets.

Charcoal manufacture offers a potential market

Fiber Potential for the half of the coarse residue that is hardwood.

However, charcoal producers are located outside the

The Current extensive use of the free wood residues study area and transportation costs are probably

for animal and poultry bedding will continue. And, prohibitive for most accumulations.
. Fuel Potential SUMMARY

The use•of secondary plant_wood residues for fuel A large portion of the wood residue in the

offers a real potential because of the low moisture Minneapolis-St. Paul area is produced by a few

content of the material. There are several types of firms. The largest individual accumulations were at

burning systems available, many requiring a homo- hardwood dimension, millwork, and pallet plants.

geneous furnish with particles less than 1/8 inch in The bulk of the material was concentrated in the

size. Thus, the fine residues would need only minor central part of the study area.

processing. The coarse residues would need chipping

or coarse hammermilling in addition to further

reduction in a free hammermiU. Fluidized bed boilers Disposal of fine residues is not a problem for

are available to burn _unprocessed coarse material, study area firms: nearly all of this material is being

although processing increases efficiency, used. A large portion is sold for animal bedding or

' burned for heat. On the other hand, coarse residues

An average of 8,500 Btu's per pound is a commonly are costly to dispose of, and nearly two-thirds are

used "higher heating" val,ue for ovendry wood. discarded as waste.

Using this base, and adjusting for average as-fired

moisture content, it is estimated there are approximately 309 billion Btu's potentially available from The residues have several desirable characteristics.

the wood residue in the study area, excluding the Most have a low moisture content and are free of

amount now being burned for plant fuel. bark. A high percentage of the fine residue are less

than 1/8 inch in size, which is desirable for suspen-

• sion burning. Contamination is not a serious

Fuel Comparisons problem, even for most of the coarse residue.

ASsuming that.No. 6 fuel oil produces 150,000 The mixture of species or kinds of material is

Btu's per gallon, costs 32¢ per gallon, and has an 80 detrimental for some uses, and low value makes

percent combustion efficiency, the cost of fuel to

sorting impractical. This is not a problem for fuel,

produce steam would be $2.67 per million Btu's. To and is the reason this use may be worthwhile

equal this coStburn_i_ngwood as a fuel, the producer considering. Also, it may not be practical to

could afford to pay as much as $!3.60 per ton for consider manufacturing a product for markets now

green wood and $28.87 per ton for dry (Arola 1975). satisfied from other sources simply because the

(Green wood is estimated to yield 4,250 Btu's per residue exists.

pound and a combustion efficiency of 60 percent;

dry _wood yield is 7,735 Btu's per pound and a o

combustion efficiency of 70 percent.) This comparison Because these residues are centrally located, and

does notconsider that capital costs for wood burning currently being placed in mechanized dumping

equipment are higher than for oil fired units. But, containers, it would seem logical the material could

where residue is available at low cost, payback be trucked to a central processing station at little

periods are encouragingly short. A similar corn- additional cost. If used to produce fuel at an

parisonfor western soft coal, assuming 8,600 Btu's existing wood products plant it would then be

per pound, a cost of $21.50 per ton, and a 70 feasible to invest in processing and boiler equipment.

percent combustion efficiency, shows a cost of The disposal cost would likely be eliminated for

• $1.79 per million Btu's. To equal this cost, the most firms. More importantly, the resource would

producer could pay as much as $9.11 per ton for be utilized.

green wood and $19.34 per ton for dry.

Weighting the wood residue not now being Used " Now that information is available on amounts,

for fuel by its moisture content and related location, and disposal of the material, careful

combustion efficiency, we estimate the material has economic analyses can be made for each potential

a fuel value of nearly $500,000 as a substitute for use as prospective utilization opportunities are

oil. identified.

5
LITERATURE CITED 1966. Sawdust floor sweeping compounds. USDA

For. Serv., For. Prod.-Lab. Res. Note FPL-0115,

Reineke, L. H. 1966. Wood flour. USDA For. Serv., 4 p., Madison, Wisconsin.

For. Prod. Lab. Res. Note FPL-0113, 13 p. Madi- Arola, Rodger. 1975. How to compare fuel values.

son, Wisconsin. USDA For. Serv., 7 p., North Cent. For. Exp.

U,- S._Department of Agriculture, Forest Service. Stn., St. Paul, Minnesota.

U. S. GOVERNMENT PRINTING OFFICE: 1977--767588/42 REGION NO. 6

6
Carpenter, Eugene M.

1977. Secondary wood residue: production, use, and potential in the twin

city area. USDA For. Serv. Res. Pap. NC-144, 6 p. North Cent. For.

Exp. Stn., St. Paul, Minnesota.

Presents volume, characteristics, disposal, and uses for wood

residues from secondary wood manufacturing plants in Minneapolis-

: St. Paul, Minnesota.

• OXFORD: 839.8(776). KEY WORDS: wood waste, waste disposal,

energy, fuel, wood products.

Carpenter, Eugene M.

1977. Secondary wood residue: production, use, and potential in the twin

city area. USDA For. Serv. Res. Pap. NC-144, 6 p. North Cent. For.

Exp. Stn., St. Paul, Minnesota.

Presents volume, characteristics, disposal, and uses for wood

residues from secondary wood manufacturing plants in MinneapolisSt. Paul, Minnesota.

o

. OXFORD: 839.8(776). KEY WORDS: wood waste, waste disposal,

energy, fuel, wood products.

• ,
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• _ Sing along w_ Woodsy and help stop pol_tion.