North Central Forest Experiment Station John H. Ohman, Director Forest Service -- U. S. Department of Agriculture

1992 Folwell Avenue

• St. Paul, Minnesota 55108 Manuscript app r oved for public ation May 12, 19 7 7

1977

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CONTENTS Pa g e 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 TWIN CITY AREA

• . Eugene M. Carpenter, Mar ket Analyst Duluth, Minnesota

..

Manufacturi n g 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 anti cipated 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 wo o d 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 de v eloped by sec on dary w ood product manuf acturers
--- in a selected metropolitan manufacturing area, to determi n e what disposal was made of the material,

_ ., ,_o_ / an d to identify physic al characteristics, location, \ 

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costs, and potential markets. /

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### The Area -_ l " ' """" ° " '

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. Pau, I I I l "ENNEPIN [

_ _ I ' / The Study encompassed the Minneapolis-St. Paul

_ : ,,_ x_J [ / 

# met o o i i . c u e

ounties of / i I " Anoka,. Dakota, H-ennepin, R amsey, and
......... J [ Washington (fig. D. Although this area is approxim ately 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 Cou nties
..... , , ,, io n 1 [.
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• DAKOTA 

### D ata Collection Data . from firm s generating le ss than 1 ton of Fi g ure 1. .-Map of Minn eapolis - St
. Paul, th e w ood re s idu e p er w eek we re c olle cte d b y telephone . Study A rea .Residu e es timate s we re collected fr om 91 firms i n amount g ene r ated. All indicated that none of th eir

selectedStan dard 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 H ardw oo d dim e n sio n an d fl oo rin g 2426 6 

## Fine Residue Mi U work and rel ated products 243 5 4 Wood co ntaine rs and p al lets 244 9 Forty-two f irms gene rated 12, 7 85 to ns of f ine Miscellaneous wood products 249 5 residues annually. These fine residues were kept Furniture 251 3 separate from other residues and trash. Twenty of F ixtures 254 14 th e 42 firms pro duced 5 0 to n s o r more annu ally and

, 91 accounted f or 98 p e rcent of th e total amou nt of fi n e residue produced. The samples of fine residue were evaluated by p l aci ng th e m ateri al i n a drum with a pe rf orated, We class i fi ed the f ree material as hardw ood 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, s awdu s t, 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 scree n ed thro ugh a Wi lliams S tandard Pulp Testin g to g ethe r b y 16 finn s. Two finn s 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 the n shaken for an other 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 shaki n g. S ieve sizes were 1 inch, 1 / 2 19 firms.

_ inch, 1 / 4 i nch, 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 ove n dry 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. Gree n 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 - thi rds o f th e f i n e re si du e h ad a

• 

## AMOUNTS A'ND KINDS mois ture co ntent o f 1 0 p erce nt or le ss , an d 22



## OF RESIDUE T able 1- Average we ight and size characte ristics for fine residue samples About 32,000 tons of residue were generated in 19 74 b y al l se c ondary woo d p ro duct manu f acturers Ki n d of
.. : : Wei g ht per : S i z e o f material l in th e stu dy are a . Of thi s , 10,2 95 ton s w e re us ed f o r material : Sampl e s : cubic foot : : : Green : Dry : <1 / 8 i nch : 1 /

8 in ch + f u el, i 0 ,1 0 1 ton s w e re dump ed o r gi ve n aw ay, an d

__ . P o

_d, .... P_o_t - - - 1 1,83 6 to ns we re so ld. ' S aw dust an d s h avi ngs 12 1 2 . I i 0 .5 6 8 32 Sawdus I : 3 14.7 I 0.0 99 I Sh a vings 2 I 0 .5 5.8 1 7 83 Fiv e m illwo r k

f i rm s bu r n e d th e i r

re sidu e fo r ' s .. pt

_ p e rc ents

w e re wei g h t ed by a nnua l

v olume

i: o d e riv e p l ant o r pr o c e ss h e at an d h en c e did not estimate th e tab l e valu e . 2

°percent w a s fr o m 10 to 25 pe rcent. O nly 13 pe rcent are a s up to 200 squ are inc h es; 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 f oreign materials c ould easily be kept separate if residues, markets were found fo r the wood portion. Occasionally paint or other finishes were found, but the most 

### C oarse Resi du e • 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 mo re than5 0 ton s annu ally; th e top five 

## D I SP O SAL yi elded slightly m o re than half the total am o unt
. Mixtures o f f

i n e an d. co ar se residues w e re cl a ssed a s 

## Fine Resi du es coar se. Only small amo unts O f f i n es w e re i n clu ded • in thesemixtu res. Most of the coarse residue is Most of the fine residues were used. Eleven firms either hardwood lumber trim or a mixtu re of reported dumping the mate rial, but they accounte d lumber, plywood and

/ or particleboard (table 2). A for less than 1 percent of the total volume. Four small amount of hardboard is included in the mixed percent of the total was used for plant fuel by two categori e s, firms. Trimmed blocks; strips, and edgings of lumber, Seventy-six percent of the fines were sold and 19 plywood, and parti c leboard 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 and shavings 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 mate rial 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 s tu'face negotiate d on an individual basis, and dep e nded somewh at

on dryn e ss,

volume , a nd lo a din g

f a c iliti e s. Pri ce s r e po_ r a ng e d

from $ 0 . 22

to $ 2 . 86 a c ubi c T a ble 2

_

Dis tribu ti on

of c oa rse

re sidu e b y sp e c i es y a rd,with $0.7 5 a n a pproxima t e a v e r a g e .

Thos e ' and kind of material fi rms gi v in g away th eir f in e res i du es seem e d satisfied to have the material removed regularly at

• Kin d o f ma t e r i a l " : N u m b e r : T o n s : P e r ce nt no c o st. : _o f firms : : L umb er- - H a r dw ood " 1 3 44 1 7 44 Lumbe r -- H ardw ood a nd • so f t w ood mix e d 3 1 3 41 1 3 

## Plywoo d --H ardw oo d

and C oarse Re s idue s so f t wo o d ' mixed i 1 7 ( 1 ) P ar tl cleb o ard--Har dw oo d a n d softwoo d mix ed 2 14 2 I Dispos a l of c o a rs e r esidu e s wa s ge ner a lly

a p r o ble m . 2 Mix e d solid _-- Ha rdwood Sixty-thr ee p e r ce nt w a s dump e d or burn e d a s w a ste and soft w ood mix e d 2 7 3 282 33 A ll mlxed 3 --H a r dw oo d a nd by 62 f irms . Mo st f irms

c ontr ac t e d

to h a ve ma t e ri a l sof twoo d mix ed 2 5 74 8 S haul ed away; a f e w u se d thei r o wn truc k s. T hi rtee n ' l Insigni f i c ant am o unt, percent w as giv en away fo r fire w ood o r y outh 2 M ±xture of lumbe r, p lywood , and / o r part:icl e b oard , group woodworking pro j ects. Two percent was used 3 1 n c lu . d e s

bot h fine a n d c o ar s e r e sid u es , fo r p l a n t o r pr o cess

h eat by thr ee

f i rms, a nd 2 2 

## I 3p e rce nt wa s S01 d to C harc oal manufac turin g p lants althou gh th e market in th e study are a is prese ntly

by two firms , somewhat unstructured, dem an d is strong an d wi ll " co mp ete with any attemp t to divert materi al to Annual dispos al c o sts 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 altern ative disposal methods including of loose litter annu ally. In addition, the broiler chipping and fuel. Ho w ever, investment require- chicken industry requires about a million cubic feet. m e nts w ere too hi gh to justi f y i ns_!! in g n ecessary Bark

- free , dry shavin gs are pref erred for thi s u se. process'rag equipment for the _mount of residue An attempt by a local processing firm to convert gene r ate d , c oars e lumbe r trim to shavin gs for animal beddin g was unsuccessful. A l th o ugh alm o s t all firms w ould w elco m e an alternati, ¢ e to dumping the residue, surprisingly Specialty markets for pet and laboratory ani mal few consi d ered dispos al 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.
. am ount relative to their costs of doing business. The manufacture of wood flour from dry wood res i du e is described b y Reineke ( 1 966)
. Primary 

## T RE ND S us e s are in the manufac ture o f linoleum, explosive s, and plastics. Total consumption is not large, and Most of the 91 firms interviewed indicated they consumer requirements are rather exacting. did n ot expect any signi fi cant change over the
• next 3 years in the amotmt or kind of residue The manufacture of floor sweeping compounds 'p r oduced. Three firms had definite expansion plans from dry sawdust is usu ally a sideline for firms and es l_imated a doubli ng of residue production. A: engaged in other wood pro cessing activity or by few firms commented that their business activity small specialty firms with local or region al distribution C L T SDA

1966 )
. Was slightly depressed and they would expect moderate increases only if the economy improved. The coarse materi al has poor potential for use as a A few others expressed the contrary view that pulp furnish because of the low moisture content, b u siness 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. S ome of the fine materi al has been used for this product. N o ne of the firms expected to substitute other

. materials f

o r the w ood co mpo n e nts in th eir produ cts B oth f ine and c o arse re s idu e can be us ed f o r or processes. Also, none indicated they planned to particieboard manufacture becau s e dry material
• change the me thods they were using. For ex ample, is usually preferred. However, no local market none planned to increase" the use of cut-to-size or exi s ts , and the supply i s too li mited, to support p ref ini s h ed p arts, whi ch mi g ht shi ft re si du e ac - • an effi c ient parti cl eb o ard mi ll . Tran sp orta
cumulation outs ide the s tudy area. tion co sts prevent the shipment of all but the highe s t quality dry s havings to regional particleboard 

## POTENTIAL USES markets . Ch arcoal m anufacture offers a potential m arket 

## Fiber Potential fo r th e hal f of th e co ar se residu e that i s hardwood. However, ch arcoal producers are located outside the The Curre nt extensive use of the f re e w ood residu es stu dy are a and tr ansportatio n costs are p rob ably for animal and p oultry bedding will c ontinue. And, pr ohi bitiv e fo r m os t accumul ations.

## . Fuel Potential SUMMARY

Th e use• of secondary plant_ wood residues f or f uel A large portion o f the wood residue in th e 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 n eed chi pp in g 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 h eating" val,ue for ovendry wood. discarded as waste. Using this base, and ad j usting for average as-fired moisture content, it is estimated there are approximately 309 billion Btu's potentially avai lable from The residues have several desirable characteristics. the wood residue in the study area, excludi n g 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 prob l em, ev en f o r m o st o f th e co ar s e re s idue. A Ss uming that
. No. 6 fuel oil produces 150,000 The mixture of spe c ies or kinds of material is Btu's per gallon, cost s 32 ¢ per gallon, and ha s an 80 detrimental for some uses, and low value makes percent combustion efficiency, the cost of fuel to s orting impractical. This is not a problem for fuel, produ c e s team w ould be $2.67 per millio n Btu ' s. To an d i s th e reas o n this us e may be w o rthwhile equal thi s co S t b urn_i_ng wood as a fuel, the producer co ns idering. Also, it may not be practical to could afford to pay as much as $!3.60 per to n for co ns ider manufacturing a product for markets now green w oo d and $28.87 per to n for dry (Arola 1975 )
. s ati sfi ed from other sources simply because the ( Green wood i s e s timated to yield 4,250 Btu' s per re s idue exi s ts . pound and a combu s tion efficie n cy of 60 perce nt; dry

_w ood yiel d is 7 ,735 Btu ' s per pou n d and a o combustio n efficiency of 70 perce nt. ) Thi s compari s o n Because these residues are centrally located, and does notc o nsider that capital co s ts for wood bu rnin g currently being plac ed in mechanized dumping equipment are higher than for o i l fired units . But, containers, it would seem logical the material could where re s idue is available at low co s t, payback be trucked to a central processing station at little p eriods are encouragi n gly short. A similar corn- additi o nal 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, an d a 70 feasible to invest in processing and boiler equipment. percent combusti o n efficiency, shows a co s t of The di sposal cost would likely be eliminated for
• $1.79 per million Btu's. To equal this co s t, the most firms. More importantly, the resource would pro ducer could pay as much as $9.11 per ton for be utilized. gree n w o od an d $ 19 . 34 p e r ton for dry. Weighting the wood residue not now being Used " Now that information is available o n amounts , for fuel by its moisture content and related location, and disp osal of the material, caref ul combusti on efficiency, we estimate the materi al has economic analyses can be made for each p otential a fuel v alue of nearly $500,000 as a substitute for use as prospective utilizatio n opp ortunities are oil. identified.
5

## LITERATURE CITED 1 9 66. S aw du st floor s weep ing co mpou n ds . U S D A For. Serv., For. Prod.

- Lab. Res. Note FPL-0 115 , Rein e ke, L. H . 1 9 66 . Wood fl our. USDA For. Serv., 4 p., Madison, Wis c onsin. For. Prod. Lab. Res. Note FPL-0 11 3, 1 3 p. Madi- Arola, Rodger. 1 97 5 . H ow to compare fuel values. son, Wi sc on s in. USDA For. Serv., 7 p., North Cent. For. Exp. U,

- S.

_Department of Agriculture, Forest Servi c e. Stn., St. Paul, Minnesota.

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

6C arpe nte r , Eu gen e M. 1 9 7 7
. S eco n dary w ood re s idu e: pr oductio n , use, and p ote nti al i n th e twi n 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
. P aul , Mi nn esota.

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

Carpenter, Eugene M. 1977. Secondary wood re s idue: production, use, and potential in the twin ci ty are a . U SDA For . S erv. Re s . Pap
. NC -1 44 , 6 p . North C e nt
. For. Exp. Stn., S t. Paul, Minne s ota. Presents volume, characteri s tic s , dispo s al, and u s e s for wood residues from secondary wood manufacturing plants in Minneapoli s St. Paul, Minnesota.

o

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

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