|
Best Practices in Wood Waste Recycling Click here for printable PDF version Process
Modifications
for
Panelboard Material: Wood Waste Issue: Fiber composite panelboard mills were originally designed and constructed to use virgin wood feedstocks as a raw material. Some of the virgin wood fiber used for the panelboard mills are from low value roundwood. This wood fiber is too small, an undesirable species or too defective for solid wood manufacturing. The remaining virgin feedstocks are typically derived from the residual chips produced by primary wood products manufacturers (sawmills and plywood plants) that use round logs for their raw material. The virgin wood fiber is generally free of non-wood contaminants and relatively uniform in specie, geometry, color, and moisture content. Millions of tons a year of such residuals are generated.
The
feedstocks
produced
from
wood
waste
for
the
panelboard
mills
are
more
complex.
They
frequently
contain
various
quantities
of
non-wood
contaminants,
consist
of
a
number
of
different
species
(softwood
and
hardwood
varieties),
lack
uniform
geometry,
include
weathered
wood
colors,
and
might
vary
significantly
in
moisture
content
(green
wood
to
kiln
dried).
These
complex
characteristics
are
a
challenge
for
the
panelboard
industry
because
their
production
systems
were
not
originally
designed
to
account
for
these
feedstock
variations.
Best Practice: This Best Practice recommends the implementation of certain processing techniques at panelboard plants when substituting waste wood derived feedstocks for a portion of the raw material supply. The general commonality among these techniques is that they allow the manufacturer to focus attention and maintain full control of the wood waste material as it enters their production process.
Specialized
Quality
Control
System.
The
complexities
of
a
wood
waste
feedstock
requires
the
panelboard
manufacturer
to
adopt
specialized
feedstock
sampling
and
analysis
techniques
to
maintain
adequate
quality
control
of
wood
waste
supplies.
The
wood
waste
feedstocks
require
a
greater
amount
of
monitoring.
The
quality
control
system
needs
to
account
for
the
possible
presence
of
non-wood
contaminants
and
a
unique
feedstock
geometry.
As
a
result,
the
manufacturer
should
customize
their
feedstock
specification
to
account
for
the
wood
waste
material
complexities
and
develop
a
workable
sampling
system
for
accurate
monitoring.
Since
a
single
delivery
of
wood
waste
feedstock
could
contain
significant
variations
within
the
load, multiple sampling might be necessary to attain
an
accurate
quality
assessment.
Segregated Storage System. Wood waste feedstocks should be stored separately from the conventional feedstocks. Segregated storage allows the manufacturer to use additional contaminant removal techniques, maintains close control over mixing with conventional feedstocks, and restricts the wood waste from use in certain product lines, if necessary. Enhanced
Contaminant
Removal
Systems.
Manufacturers
should
consider
enhancing
their
contaminant
removal
systems
to
ensure
the
wood
waste
feedstocks
do
not
contain
contaminated
materials.
Possible
contaminant
removal
systems
include
magnets
for
ferrous
metals,
air
density
separators
for
hard
contaminants
(non-ferrous
metals,
rocks,
glass,
etc.),
air
density
separators
for
soft
contaminants
(some
plastics,
paper,
cloth,
rubber,
Styrofoam,
etc.),
and
chip
washers
for
dirt
or
grit.
Effective
contaminant
removal
systems
would
also
allow
the
manufacturer
to
blend
higher
percentages
of
wood
waste
material
into
their
process.
Controlled Blend with Conventional Feedstock. Manufacturers should maintain a separate material handling system for the wood waste feedstocks so that operators can meter this material into the production process at a controlled rate. In general, the waste wood material is less likely to cause manufacturing and end product problems when it is blended with the conventional feedstock. In the absence of an accurate metering system, manufacturers run the risk of allowing a spike in the percentage of wood waste material which could lead to problems with processing equipment or end products.
Implementation: The substitution of wood waste feedstocks for
conventional
virgin
wood
feedstocks
is
not
a
straight
forward
interchange.
Composite
panelboard
manufacturers
need
to
carefully
account
for
the
inherent
complexities
of
waste
wood
derived
feedstocks
and
customize
a
segregated
system
for
introducing
this
material
into
their
manufacturing
process.
The
preparation
for
wood
waste
materials
is
likely
to
require
capital
investments
for
the
modification
of
raw
material
preparation
equipment
at
the
front
end
of
the
panelboard
plant.
The
manufacturer
should
work
closely
with
wood
waste
suppliers
to
fully
understand
the
quality
characteristics
of
the
alternative
feedstock. The manufacturer can then adopt appropriate
process
modifications
that
will
neutralize
any
adverse
characteristics
of
the
raw
material.
Benefits: The implementation of certain processing techniques at composite panelboard plants will allow for the substitution of waste wood derived feedstocks for a portion of their raw material supply. The ability to process wood waste derived feedstocks expands raw material base and sourcing flexibility of the panelboard manufacturer. Under certain fiber market conditions, this sourcing flexibility is extremely advantageous in keeping raw material costs as low as possible. The capability to process wood waste derived feedstocks also anticipates possible future shortages in the supply of virgin wood feedstocks.
Application Site: Manufacturing Site.
Contact: For
more
information
about
this
Best
Practice
contact
CWC
(206)
443‑7746,
e-mail
info@cwc.org.
References:
1. International Resources Unlimited, Inc. Eugene, OR. 2. Smith, David. CE/Western Engineering. Albany, OR.
Issue
Date
/
Update: March
1997 |
