The generation and utilization of residuals from composite panel products.

The typical composite panel plant in North America generates over 100 tons per day of residuals while manufacturing hardboard, particleboard, or medium density fiberboard (MDF). Usually, over 90 percent of these materials are either returned to the manufacturing process or burned to generate process heat. Residuals are also generated by secondary manufacturers during the conversion of panels to finished consumer products. There is less opportunity to recycle these materials internally, so disposal outlets must be found.

In this article, the residual generation and utilization practices of manufacturers of both primary and secondary composite panel products are characterized. Opportunities for downstream recycling are identified and discussed, and suggestions for enhancing residual utilization are offered.

The Initial Idea

In 2002, the Composite Panel Association (CPA) commissioned a project with the overall objective of "characterizing the landscape of common practices related to disposal and recycling issues for the composite panel industry." The study was conceived because CPA members had shown interest in promoting greater utilization of industrial composite wood panels and residuals generated during their manufacture, and conversion of these materials into furniture, cabinetry, architectural millwork, and other finished products. The study had the following specific objectives:

1. Establish a benchmark of the industry's current residual generation rates and utilization practices.

2. Identify opportunities for expanding and improving the utilization of residual materials through further study and other means.

3. Create a reference list of documents, information sources, and experts in the field of wood recycling and residual utilization.

For the purposes of the study, the composite panel industry was defined to include primary manufacturers of particleboard, MDF, agriboard, and hardboard, and secondary manufacturers, who either added value to those panels through further processing or converted them into finished consumer products. Other composite panels such as oriented strandboard (OSB), plywood, and wood/plastic composites were not included in the study.

Various types of residual materials are generated during the production of composite panels. These include saw trim, sanderdust, mat trim, reject panels, and wood particles and fiber rejected from the process or accumulated through clean-up activities. Secondary manufacturers also generate trimmings, dust, and rejects, but residuals from these sources may also be contaminated with non-wood materials such as paint coatings and laminates. Each of these residuals has unique characteristics that influence utilization opportunities. This study endeavored to understand their value and to find out what is, and can be, done with them.

It is important to point out that the purpose of this project should not be confused with exploring the use of recycled or urban wood in the manufacture of hardboard, particleboard, and MDF. This study focused on residual materials generated during the manufacture of composite panels and subsequent conversion into finished products.

The Study Approach

The project was conducted in two phases. The first phase was to conduct a global literature review with the objective of identifying the present state of knowledge and practices associated with the utilization of particleboard, MDF, and hardboard residues. The search looked for information regarding residuals generated by both primary and secondary manufacturers, as well as finished products discarded after their useful life.

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During the second phase of the study, a bench-marking survey of board plants and converting operations was conducted. A questionnaire was distributed to over 140 operating facilities in the United States and Canada. It inquired about their residual generation rates and utilization practices. The plants were also asked about the economics of recycling, the importance of residual management and disposal to their operation, and ideas on how residual utilization could be expanded and improved. The survey responses from the two groups were broken into the separate categories of primary board manufacturers and secondary manufacturers for analysis.

Summary of Findings

A report on the Global Literature Review was issued to CPA members in June 2002. The complete reference bibliography generated by the review is available from CPA. The review found and identified a large number of documents, organizations, and individuals associated with the recycling and reuse of waste wood. However, it also determined that very little information has been published on the specific subject of utilization of residuals generated from North American composite panels. No documents were identified that specifically addressed residual generation rates, utilization, or recycling practices by either primary or secondary manufacturers. None of the websites or expert contacts were able to identify any current research work or specific regulatory focus. There are a few companies doing work in this area, but they have not published their findings.

To the extent that the subject is addressed at all in the public arena, it is done so peripherally as part of the more general subject of waste wood recycling. In this area, there is a fair amount of information regarding the characteristics of the waste wood stream and markets for recycling. However, particleboard and MDF residuals are seldom (if ever) specifically addressed, other than to be statistically included in the categories of "treated wood" or "engineered wood." What is common (but not the focus of this study) is the identification of composite board plants as markets for other forms of recycled wood.

Interest in the overall subject of wood recycling in North America seems to have peaked in the mid-1990s and has since declined. Many of the references found were published between 1995 and 1999. Discussions with experts indicate that the main reason for this is that funding sources for supporting recycling and waste stream diversion activities have dried up. Without subsidies, the economics of many wood recycling alternatives are not as practical. Many state agencies are still promoting wood recycling efforts, but due to lack of funding, do not show the same vigor they did several years ago.

In Europe, the interest activity level is somewhat higher. Existing and pending environmental regulations, as well as a more limited wood supply, have motivated development of technologies to process old furniture back into particleboard and MDF raw material. Some newer board plants have been built with large energy co-generation facilities, and have established contracts with secondary manufacturers to return their residuals for utilization as fuel. This trend is expected to continue, as access to landfills for materials with fuel-value becomes increasingly restricted.

Composite board plants were found, for the most part, to be doing a good job of internal recycling. These plants are basically recyclers to begin with, since most of their raw materials come as residues from other primary manufacturing operations. Consequently, most newer facilities, and many of the older ones, are well equipped to minimize the generation of residuals, and efficiently manage the utilization of what they do produce. Still, for some plants, residual utilization is a significant burden, and all facilities would benefit from the development of more economic markets for their materials.

The average raw material consumption rate in the North American board plants surveyed is about 1.44 bdt/MSF, 3/4 inch, or 2,880 pounds of dry wood per MSF of 3/4-inch-thick panels. Based on an average weight of the wood in a finished panel, this indicates that, on average, about 90 percent of the wood entering board plants is converted into salable product. Most of the rest is burned, either to fuel the boardmaking process, or in offsite energy plants. Some reject panels are used for packaging and dunnage. Offsite recycling activities are limited to only about 2 percent of the residuals generated. Some plants are able to avoid sending any residual materials to the landfill, but the overall generation rate of true "waste" materials currently averages about 3 tons per day per board plant.

The residual generation and utilization practices of secondary manufacturers vary with the type of operation. Most operations achieve conversion yields from panels of over 90 percent, but some furniture and MDF moulding yields can be considerably less. Some larger secondary operations are able to burn residuals for process and building heat needs, but for most, internal recycling opportunities are limited to using off-cuts and scrap for packaging applications. Landfilling is common, but so is some offsite recycling.

Non-fuel recycling markets are small and hard to find for composite panel residuals. Most receivers pay only a nominal price to the generator, so disposal usually is at a cost for both board plants and secondary manufacturers. Some companies have found small markets that will pay a few dollars per ton above hauling costs, but most are lucky to break even by trading the material for the cost of freight. Generators who take a "product" approach to their residuals have the best chance of finding a buyer. This involves high-grading the materials, or taking care to ensure they conform to a consistent quality specification. The largest utilization and recycling market is for fuel, followed by soil amendment, animal bedding and poultry litter, compost, and solidification of liquid wastes (absorbents). Some operations are able to sell scrap and reject panels for a few dollars per ton to junk dealers and packaging brokers, but most are lucky to break even on the freight.

Discussion of Findings: Board Plants

The goal of the benchmark survey was to seek information from every particleboard, MDF, and hardboard plant in the United States and Canada. A total of 80 survey questionnaires were sent out to this group, and a concerted effort was made to verify delivery to appropriate, knowledgeable individuals at each site, and to encourage comprehensive responses. Fifty-seven (or 71%) of the board plants returned completed responses.

By compiling the survey results we can characterize both the average board plant, and the general practices of the industry. Table 1 shows that raw material consumption rates vary widely among plants. While the overall average is 1.44 bdt/MSF, 3/4 inch (bone dry tons per thousand square feet, 3/4-inch basis), consumption rates vary from 0.96 to 1.84 bdt/MSF. This consumption rate is influenced by three factors. The first is the age or technology level of the mill. Newer technologies, particularly continuous presses and centralized integrated control systems, allow for smooth production of consistent products that result in lower board densities and lower residual generation rates. For example, the amount of trim and sanderdust generated by an operation with a 10-foot-wide continuous press may be only a third of that generated by a plant with a 30-year-old multi-opening press line.

The second factor that influences wood consumption is the plant's product mix. Plants that focus on lower density, thicker products, and large panel sizes will use less wood than those that make higher density and thinner products. Also, particleboard tends to be lower density than MDF and hardboard. The plants reporting the lowest usage factors specialize in making thick, low-density particleboard door core.

The third factor is the plant's residual utilization practices. Those plants that make a point of recycling trim or sanderdust back into the process will use less raw material than those that direct those materials to fuel or elsewhere.

Table 2 shows that the typical North American board plant generates around 112 tons per day of residues. Over a third, 44 tons, is in the form of sanderdust. While many mills burn all of their dust, some are unable to because of environmental restrictions on either particulate or nitrogen oxide emissions. On average, about 65 percent of all sanderdust is burned onsite in either dryers or boilers. Most of the rest is recycled back into the board. In some areas, the sanderdust has a higher value as a raw material than as a fuel, so is recycled even though burning might be permitted. Sanderdust is a very difficult material to handle. The very fine powder is best kept contained in silos and transported with pneumatic systems. Special equipment is required to load and unload trucks to avoid heavy dust losses. So, even though it is an excellent fuel and has a good potential for industrial use as wood flour, less than 10 percent of what is generated in North American board plants is transported off site.

Mat trim and rejected mats are the next largest category of board plant residues. Nearly all of this unpressed material is recycled back into the board as a matter of course, but small amounts are burned or taken to landfills when highly contaminated.

Board trim and sawdust from panel sizing operations is generated in the average mill at a rate of 25 tons per day. Seventy percent is recycled back into the board, and most of the rest is burned onsite.

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Board reject is made up of blows, broken, or water-damaged panels, and very poor quality production made under upset conditions. Most mills are equipped with board breakers and hogs that allow them to chop the boards into small pieces and either use the material for fuel, or recycle it back into the board. The survey indicated that over half of all reject board is burned, while another 21 percent is recycled back into the board. A fair amount is also used to make stickers (unit bolsters) or other packaging material. About 6 percent is utilized offsite, and the remaining 4 percent ends up in landfills.

The most difficult material for board plants to deal with is floor sweepings and furnish diverted to dump vaults during startup or emergency incidents. While still mostly wood, these residual materials are often contaminated or wet, and difficult to get rid off. Some recycling opportunities have been found as soil amendment or compost, but the markets are small and quickly saturated. About 22 percent of this material is used as onsite fuel; 18 percent is recycled back into the board manufacturing process. But over half of the clean-up waste is hauled offsite at a loss and is either burned or dumped in a landfill.

Overall, the most popular strategy for dealing with board plant residues is to recycle the materials back into the board. About a third is used to fuel the plant's needs for steam and process heat. Less than 10 percent of the total residuals generated in a typical board plant are transported offsite, and 60 percent of these are used as fuel. Another 25 percent are taken to a landfill, and only about 15 percent are otherwise recycled.

When asked if residuals were more valuable as fuel or raw material, about half said raw material, and a third said fuel. The remaining mills responded that sanderdust was more valuable as fuel, but board trim and sawdust had a higher value when recycled back into the board. In most regions, the costs of raw materials and thermal fuels are very similar, but in some areas one or the other may be considerably more expensive. Two examples of the relationship between a residual's fuel value and raw material acquisition costs are shown in Table 3.

The delivered costs of natural gas, oil, and other fuels are volatile, but currently range from a low of about $3.50/million BTUs, upward to as much as $10/million BTUs. It should be noted that the fuel value estimates listed in Table 3 do not represent the total cost of using residues for fuel. The costs of installing and operating fuel-handling systems and pollution control devices can influence the economic comparison with other fuels.

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The main offsite recycling uses for board plant residues (other than fuel), are soil amendment, compost, animal bedding, wood flour fillers and extenders, and landscape mulch. Many board plants would prefer to sell some of their residuals rather than recycle them internally, but the available markets are small and uneconomical. The residuals are often sold at a loss, even for fuel applications.

Of the responding mills, about half reported that they ship some of their residuals into offsite fuel markets. However, nearly half of those mills sell at a loss, while another 22 percent break even, and only 30 percent are able to sell their materials for prices higher than the transportation cost (Table 4).

Several of the responding mills deal with one or more of the non-fuel, offsite recycling markets. With only one small exception, these markets are unprofitable to the board plant. Sometimes the mills are able to give their residuals away without incurring transportation costs, but the mill usually has to pay a fee of $10 per ton or more to get the recycler to take the material. However, recycling is still more economical than disposing of mill residues in a landfill. The average landfill cost was reported to be about $31/ton.

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Still, most board plants do not regard the disposal of residuals to be an important issue. Of the plants surveyed, only 25 percent indicated it was a problem for them. It appears that most mills have developed the capability to internally recycle or reuse most, if not all, of the residual materials they generate.

For those mills that do regard residuals as a problem to manage, most cited a lack of system capability as the reason. Recycling residuals back into the board requires careful control to avoid upsetting the process or affecting board quality. Many of these mills have been unable to obtain the capital to install the special storage and handling systems needed to properly manage recycling of residuals. So even though recycling and landfill costs are high, their offset does not provide sufficient payback to justify new capital investment. Nearly all of the mills that are having a problem with their residuals are older facilities.

Discussion of Findings: Secondary Manufacturers

The overall survey response rate from the secondary-manufacturing sector of the industry was disappointing. This sector is made up of thousands of firms, ranging from small local custom cabinet shops to huge furniture companies with several installations. In hopes of identifying those companies most likely to respond, the targeted firms were selected from the membership of the Composite Wood Council (CWC), and supplemented with recommendations from primary board manufacturers. However, even with repeated follow-up, only 21 out of 67 questionnaires were returned, a 31 percent response rate. But the respondents did represent a good cross section of the industry, so some meaningful insights into their practices and experiences can be gained.

Because secondary manufacturers are such a diverse group, Table 5 shows how the responses where segregated into five sub-categories for analysis.

The yield from converting raw panels into higher value products is dependent on the nature of the converting operation. Custom laminators and board plants doing either lamination, or value-added cut-to-size, achieve yields in the 96 to 99 percent range. That yield falls to about 91 percent for custom component manufacturers, and averages about 88 percent when making furniture, kitchen cabinet, and other finished products. Yield varies widely in the MDF moulding business, and is very dependent on specific patterns. Ornate crown mouldings and narrow coves may have a yield as low as 65 percent, while simple base mouldings give a 95 percent conversion into finished product. The overall average yield from MDF moulding operations was reported to be about 77 percent.

In all cases, the yield loss volume becomes residual material. The ease with which the secondary manufacturer is able to deal with the residuals is highly related to the size and complexity of the operation or their company. The value-added board plants have little trouble being able to recycle residuals by mingling them with those generated in their primary manufacturing operation. Some large furniture plants have sufficient needs for thermal energy to justify the operation of boilers and the residual handling systems to feed them. One such facility has also been able to see a payback in investing in equipment for high-grading and segregating residuals to make them more attractive to down-stream recyclers. Although this facility generates as much as 300 tons per day of residual materials, it is able to profit from them through a sophisticated onsite/offsite fuel program, and a mix of several recycle market outlets. The key to this plant's success is recognition of the value to operations of eliminating residuals as a "problem," and a commitment to managing their reutilization to the highest possible value.

For the most part, however, dealing with residuals is not easy for secondary manufactures. Because many of these operations and companies are small, they lack not only the capital, but also the management resources to efficiently deal with them. Consequently, a very large percentage of secondary residuals are disposed of at a significant cost to the manufacturer.

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The industry segment that has been most successful in finding recycling outlets for their residuals is the MDF moulding manufacturers. All five of the respondents reported they currently send none of their residuals to landfills. They all co-mingle their sawdust, shavings, and sanderdust, and haul it out in trucks. Four of the five send it all to recyclers, at a cost ranging from break even to $10/ton, where it is used as animal bedding, compost, or soil amendment. The fifth moulder pays $16/ton to have its residuals transported to power plants where it is used as fuel.

Five of the seven finished-product manufacturers that responded also send some of their residuals into offsite recycling markets. The material finds its way into animal bedding, compost, or soil amendment markets at a cost to the producer ranging from break even to $24/ton. All of these producers work with contract haulers that either double as, or resell to, the recycler. The sixth producer, who generates about 90 tons per week of residuals, is located in a rural area where landfill costs are only $23/ton, and no recycling alternatives are available.

The seventh producer is the large furniture manufacturer mentioned earlier, who has actually developed some attractive markets for its residues. They sell about 100 tons per day of material to several outlets, including animal bedding, wood flour for industrial uses, and solidification agents for liquid waste, for prices above hauling costs ranging from $10 to $40 per ton. This should not, however, be considered all profit, because they have incurred some processing and handling costs to prepare the residues to meet the quality requirements of the application. However, discussions with the producer indicate that their program to add value to residuals does contribute positive cash flow to the operation.

With all secondary manufacturers, the landfill is the destination of last resort for un-recyclable residues from composite panels. Landfill dumping costs vary with location, and range from $23 to $50 per ton. The vast majority of the residues are contaminated with small amounts of laminate and coatings used as finishing materials. The exception is the MDF moulders, which generate mainly pure MDF dust and shavings, although a small amount may contain a bit of water-based coating.

Table 6 shows the percentage of respondents reporting various types of contamination in secondary residues. The level of contamination varies, but is always very small. In operations using laminates, virtually all of the residues will be contaminated at the 0.5 to 2 percent level with laminate material. Where coatings are used, usually only 10 percent or less of the residues are contaminated with small amounts of coating. It should also be noted that since the origin of these residuals is composite panel products, they contain cured resin (usually urea formaldehyde) as well as wood.

Landfills have not found these contaminates to be objectionable, and only one producer mentioned them as disqualifying the material for use in other recycling applications. When asked about factors limiting opportunities to recycle more residuals, 57 percent did not identify a reason. The rest cited lack of markets, hauling costs, and capital costs as impediments to further recycling.

Opportunities for Cooperation Between Primary and Secondary Manufacturers

One of the factors that prompted CPA to commission this study was the report from its members that their secondary manufacturing customers were looking for help with managing their residual materials. Some had inquired about returning their residuals to the board plants for recycling, while others were asking for technical assistance with either fuel burning, or environmental impacts associated with composting or soil amendment applications. To investigate how widespread this interest/need is, the board plants were asked in the survey if any of their customers had asked about returning their residuals, and what their response had been.

Not surprisingly, 45 percent of the board plants said they had been approached on the subject by one or more of their customers. Most frequently, the request was to return packaging materials such as unit stickers, cover boards, and dunnage. About a quarter of the board plants in North America have agreed to accept these materials as a way of providing a service to their customers, and now have at least some limited program in place. Some mills are actually paying both freight and a material price on items like stickers in "good condition." Others pay only freight. Several other mills are buying clean residuals from local customers, when transportation costs make sense, for use as either raw material or boiler fuel. About a third of the mills that have been approached by customers have declined to take back residual materials, citing high costs or excessive volumes as reasons.

Opportunities for Enhancing Residual Utilization

Although most board mills have residual management under pretty good control, many would welcome development of larger and more economical recycling markets. The greatest area of need for expanding recycling and utilization opportunities probably lies with residuals generated at the secondary manufacturing level. For many manufacturers, the costs for disposal of these materials are significant enough to impact the viability of their business. By finding ways to help these operations reduce their costs, the whole industry will benefit from the increased attractiveness of composite panels in both the marketplace and the environment.

One of the goals of this study was to develop some topics and direction for future work. Some of the interesting ideas expressed by survey respondents for expanding residual utilization opportunities include:

* Gain a better understanding of how to use composite panel wood waste as fiber sources for compost. Impacts of formaldehyde and ammonia are of particular interest.

* Develop methods and programs for composting board residuals in combination with municipal waste.

* Develop methods for blending residuals with poultry litter, and methods for converting spent litter into a viable boiler fuel.

* Learn how to make the composite board manufacturing process more thermally efficient to allow more material to be recycled back into the board rather than burned as fuel.

* Study alternative uses for sanderdust, such as molded furniture parts and wood/plastic composite decking.

* Gain a better understanding of the impact of grit in sanderdust on wood flour applications.

* Develop educational materials describing the best practices for transporting sanderdust and other residuals from board plants to power stations and other facilities.

* Develop technologies to convert residuals into other more practical forms of fuel, such as pellets, cubes, or briquettes.

* Find better ways to convert finished and laminated products back into raw material for board making.

* Develop monetary incentives to make it more economical for board producers to invest in recycling equipment and co-generation systems.

* Lobby for modification of emissions regulations, or other incentives to make it more attractive to burn residuals instead of fossil fuels.

* Develop procedures for reducing the transportation costs of returning secondary residuals to the board plants for recycling.

* Prepare educational materials describing how secondary residuals can safely be recycled as soil amendments, compost, and solidification agents.

Another of the project's goals was to identify new or novel recycling technologies. The results in this area were disappointing. The only interesting technology identified involves using steam to "digest" reject panels or old furniture to break down the resins, allowing laminates and hardware to be easily separated from the wood furnish. After cleaning, the furnish can be further screened into different size fractions, and recycled back into the particleboard manufacturing process. This technology was originally developed and patented by WKI in Germany. One production facility has been built in northern Europe. The furnish prepared in this way reportedly makes a better quality board than residuals sized by mechanical means. One U.S. manufacturer has independently developed and tested a similar technology, but found the economics to be unattractive.

Conclusions

Although wood recycling in general has emerged as a topic of considerable interest, little attention has been paid to the utilization of residuals generated during the manufacture of composite panels and subsequent conversion into finished products. This study has determined that very little published information is available on this specific subject, and this lack of knowledge may be a contributing factor to the limited size of recycling markets.

The modern composite panel industry is a highly efficient user of wood residuals generated not only by other primary forest products industries, but by its own operations as well. Today's board plants are well equipped to minimize the generation of residuals during manufacture, and to return what is generated to the process, in the forms of thermal energy, raw material, and finished-product packaging. Mills built or refurbished in recent years use far less wood and generate far less waste than older facilities. An ever-increasing number of these mills are also helping their customers to manage residuals generated at the secondary manufacturing facility through programs to return packaging materials and trim losses to the board plants for reuse.

However, too much material is still dumped in landfills. A strong need exists, mainly with older board plants and secondary manufacturers, for utilization or recycling applications for composite panel residuals. While some producers have found opportunities with fuel, compost, animal bedding, and waste solidification applications, these markets are small, regional, and often uneconomical. Very few residual generators are able to command better than break-even pricing in these applications, and most must pay to have their residuals hauled away.

Utilization of Board Plant Residuals

Back in board  55%
Onsite Fuel    34%
Offsite Fuel    6%
Recycle use     2%
Landfill        2%
Packaging       1%

Note: Table made from pie chart.

Table 1.--Composite Board Plant Wood Consumption Rates.

Average value   1.44 bdt/MSF, 3/4in.

Std. deviation  0.19

Avg.deviation   0.15

Range           0.96 to 1.84 bdt/MSF

Table 2.--Composite Board Plant Residual Generation Rates.

                                              Residual use

                          Average
                      generation rate  Back into  Onsite  Offsite
   Residual type      (bdt/day/mill)     board     fuel   fuel

Clean-up, dumps              6.8         17.7%    21.9%    29.3%

Mat reject, trim            29.7         95.2%     2.4%     0.2%

Board reject                 7.1         55.4%    21.1%     3.8%

Board trim                  25.1         70.3%    25.5%     4.6%

Sanderdust                  43.6         25.5%    64.9%      7%

Total (bdt/day/mill)       112.3         62.2     38.4      6.5

Percent                    100%          55.4%    34.2%     5.8%

                              Residual use

                                Recycle
   Residual type      Landfill    use    Packaging

Clean-up, dumps        22.2%      9%         0%

Mat reject, trim        2.2%      0%         0%

Board reject            3.7%     2.5%      13.6%

Board trim               0%       0%        0.9%

Sanderdust              0.3%     2.2%        0%

Total (bdt/day/mill)    2.6      1.7        1.2

Percent                 2.3%     1.6%       1.1%

Table 3.--Fuel Value of Residuals. (a)

     Average raw       Trim and sanderdust  Clean-up and reject
material cost ($/bdt)   ($/million BTUs)     ($/million BTUs)

         25                   $1.47                $2.50

         30                   $1.76                $3.00

         35                   $2.06                $3.50

         40                   $2.35                $4.00

         45                   $2.65                $4.50

         50                   $2.94                $5.00

         60                   $3.53                $6.00

         70                   $4.12                $7.00

        100                   $5.88               $10.00

(a) The typical fuel value of trim and sanderdust at 5 percent MC is
assumed to be 8,500 BTUs per pound; the typical fuel value of clean-up
and reject furnish at 40 percent MC is assumed to be 5,000 BTUs
per pound.

Table 4--Economics of Offsite Residual Utilization.

Offsite residual      Mills engaged             Mills selling
  utilization     (% of all respondents)

                                          % of engaged  Avg. $/ton

Fuel                       49.1                30           $5

Compost                     9.1                 0

Soil amendment              7.3                 0

Landscaping                 1.8                 0

Animal bedding              5.5                33           $6

Wood flour                  3.6                 0

Landfill                   41.8                 0

Other                       0.0                 0

Offsite residual         Mills paying        Mills breaking even
  utilization

                  % of engaged  Avg. $/ton     % of engaged

Fuel                   48          $13              22

Compost               100          $12

Soil amendment         50          $10              50

Landscaping             0                          100

Animal bedding         33           $6              33

Wood flour             50          $30              50

Landfill              100          $31

Other                   0

Table 5--Responses from Secondary Manufacturers.

    Types of secondary manufacturers responding

                                  No.  % of responses

MDF mouldings                      5        23.8

Value-added board plants           4        19.0

Custom laminators                  2         9.5

Furniture, cabinet, product mfg.   7        33.3

Custom cut-up and
component mfg.                     3        14.3

Total responses                   21

    Types of secondary             Is disposal/recycling a big
  manufacturers responding        problem for your operation?

                                      Yes %          No %

MDF mouldings                          60             40

Value-added board plants               25             75

Custom laminators                      50             50

Furniture, cabinet, product mfg.       57             43

Custom cut-up and
component mfg.                         33             67

Total responses                        48             52

    Types of secondary            What is the average conversion
  manufacturers responding         yield from composite panels?

                                   Avg. yield (%)    Range

MDF mouldings                           77          67 to 95

Value-added board plants                98          96 to 99

Custom laminators                       97        96.5 to 98+

Furniture, cabinet, product mfg.        88          78 to 92

Custom cut-up and
component mfg.                          91          89 to 93

Total responses

Table 6--Contamination in Secondary Residues.

     Contaminated residuals?       No. reporting  % of respondents

HPL, melamine, and paper laminate       11              52.4

Plastic and vinyl laminate               4              19.0

Water-based coatings                     5              23.8

Solvent-based coatings                   3              14.3

Toxic materials                          0               0.0

The author is a Senior Process Specialist, Evergreen Engineering, Inc., Eugene, OR. An extensive list of relevant references was compiled for this project and you may obtain the list from the Composite Panel Association. 18922 Premiere Court, Gaithersburg, MD 20879; 301-670-0604; www.pbmdf.com.