Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02846721 2014-03-17
THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAMED ARE DEFINED AS FOLLOWS:
FIELD OF THE INVENTION
This invention pertains to a recovery of bitumen from a recycled asphalt based
roof
scraps, acquired in a process of replacement of commercial and residential
flat and low
slope roof systems.
BACKGROUND OF THE INVENTION
The Canadian industrial and commercial low-slope roofing market uses a vast
array
of roofing products and systems. There are conventional roofs and protected
membrane
roofs, single ply roofs and multiple ply roofs, comprising numerous types of
membranes
and built-up roof systems. Roofing asphalt or bitumen is utilized in several
types of roof
systems including: traditional four-ply built-up roofs, two-ply modified
bitumen roofs
and rubberized asphalt roof. Modified bitumen and asphalt built-up roof
systems
combined account for as much as 80% of the annual Canadian low slope roofing
market. The recent Canadian Roofing Contractors' Association estimates that
Canadian
commercial roofing sector sales approach $1.6 billion on an annual basis. The
CRCA
estimates that the roof replacement accounts for approximately 60% of all
roofing
works activity. As result, it was estimated that about 330,000 tonnes of
asphalt
containing roofing scrap being produced by the roofing sector annually, while
the re-
roofing accounts for about 99% of the total waste stream.
Potential use markets identified for residential and commercial asphalt
roofing scrap
are currently: hot-mix asphalt and cold patch, dust control on countryside
roads and
temporary roads, driveways and parking lots, aggregate base and fuel.
Current processes for roof material recycling include crushing the material
into a
homogeneous mix. This mix can be used as a filler as is. Ultimately it can be
used to
generate pure bitumen through thermo-mechanical separation, such as melting
the
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bitumen and squishing it from the mix through a finely porous membrane. This
process
is expensive and in many cases not economically feasible.
Additional issue with the roofing in North America is a use of gravel and
stones,
compounded with the top layer of Build-Up roof and use as protection from
ultraviolet
impact. The current crushing and separating techniques are not adapted to work
with
mix of bitumen, paper, stones and gravel.
In Canada, asphalt based roofing scrap has been incorporated in hot-mix
asphalt
production, trail construction and as a fuel in cement kilns. Some provinces
(Ontario
and Nova Scotia) have provisions for using up to 5% of recycled asphalt
shingles in a
hot-mix asphalt production. It is estimated that there are over 500 hot-mix
asphalt
plants across Canada producing in the order of 30 to 31 million tonnes
annually.
Substitution of even 5% of the virgin material in hot-mix asphalt could
consume in the
order of 1.5 million tonnes of asphalt roofing scrap generated in Canada
annually.
Further, it is estimated that a substituting of even 5% roofing scrap for
virgin asphalt
concrete would eliminate 90,000 tonnes of greenhouse gases produced by the hot-
mix
asphalt industry.
The benefits of recycling asphalt based roofing products include conservation
of
landfill space and resources, reduced costs of disposal, and lower costs of
production as
compared to new roofing products made from virgin materials.
Therefore there is a need for an improved process for recovering asphalt from
the
roofing scraps, to reduce an environmental impact of the construction waste
and also to
save on resources in manufacturing of hot-mix asphalt products.
SUMMARY OF THE INVENTION
This invention pertains to a recovery of bitumen from a recycled asphalt based
roof
scraps, acquired in process of replacement of commercial and residential flat
and low
slope roof systems.
The present invention is based on the discovery that when bitumen roof
assembly
become deteriorated as effect of weather impact it actively absorbs
atmospheric
moisture. This moisture, entrapped inside layers of bitumen and roofing felt
makes the
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layered materials more fragile and prone to fracturing. After an extensive
research it
was found that this phenomenon can be used for assisted separation of the
bitumen
from the surrounded materials by crushing with hitting and hammering. This
separation
is possible because the "old moisture-laden bitumen" ceases to be effective
bonding
material for layers of roofing felt, thus promoting fracturing.
This mechanical separation by breaking allows recovering high amount of
bitumen
from the recycled material with lower capital and operational costs.
Following the mechanical fracturing/breaking, a separation, dehydration and
recovery processes make it possible to regenerate a substantial amount of
bitumen for
secondary use.
Therefore, one aspect of the invention is a use of a cold separation process
for
separating bitumen from roofing scrap materials. Following the cold separation
process,
purification and regeneration of bitumen, allows use of this bitumen in a wide
range of
application of bituminous materials for renovation and restoration roof and
other
systems.
According to one aspect of the invention, in the cold bitumen extracting
process, the
mix of torn off old roofing materials is preliminarily sorted with bitumen
roofing
membrane abjection and periodically loaded to continuously working horizontal
cylinder-shaped rotor type impact extractor. In the extractor, material is
exposed to
additional impact grinding with splitting off layers of bitumen from felt
base. Further,
the generated mix consisted from split bitumen crumbs, roofing felt chips and
gravel
continuously moved into wire mesh equipped drum separator. Result of
separation
process is the making of homogeneous mix, consisted from bitumen crumbs. Batch
of
bitumen crumbs is loaded to heat reactor and underwent thermo dehydration
under
temperature of 60-250 co, preferably about 160-200 co more preferably about
180 C.
During dehydration process liquid bitumen is periodically mixed and recovered
by
injection of volatile and modifier compounds known in the art to add
elasticity and
reduce melting point of the bitumen.
The improvement further comprising a method to recycle torn-off
asphalt/bitumen
based old roofing scrap material whereby described above double-stage low
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temperature process with recovering secondary bitumen for further using at
roofing,
constructions, roads and other applications.
Preferably the preliminary chopped roofing materials are being separated into
bitumen crumbs and bitumen saturated roofing felt chips in the cylinder-shaped
rotor
type impact extractor. The impact extractor consists of rotating cylinder
capable of
rotation with 400-600 rpm. Said cylinder is being equipped with a plurality of
hitting
elements such as teeth of hammers. Cylinder has preferably about 20-30 sized
4"x4"
non-sharped impact teeth. The size and geometry of these teeth may be adapted
to the
apparatus; also the number of such teeth per cylinder may vary. The teeth are
preferably non-sharped, thus they provide mostly hitting/ crushing/ grinding
destructive
action. Preferably these teeth are not cutting the material.
However in an alternative embodiment a cutting devise can be further utilized.
In an alternative embodiment the extractor can be equipped with additional
destructive features known in the art for example: vibrating and/or ultrasonic
features.
According to another aspect of the invention, the preliminary chopped,
separated
and averaged bitumen crumbs mix underwent thermo dehydration in preferably
vertical
type oil-jacketed reactor equipped with a heating system with temperature
interval 60 -
250 C, equipped with mechanical agitator and tap-holes to separately release
recovered
secondary bitumen and the bitumen fouled with mineral slurry.
According to further aspect of the invention, after the separation, roofing
felt chips
comprising bitumen and paper, underwent thermo dehydration in a vertical type
oil-
jacketed reactor equipped with a heating system with temperature interval 60 -
250 C
with simultaneous mixing and smoothing in hot condition. This mixture can
further be
used to produce various bituminous core products to use in roofing and
waterproofing
applications, such as the bituminous mineral core board for torch down roofing
application and bituminous mastics for cold processing in roofing and
waterproofing
applications.
According to yet another aspect of the invention there is provided a method
for
recycling asphalt based roofing material; the process comprises a cold
mechanical
crushing of the roofing material by impact, and separating said crushed
material by a
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mechanical separation, into a first mix material comprising mostly bitumen and
a
second mix material comprising bitumen, felt and gravel.
Preferably, first mix material is further purified by dehydration, mixed with
volatile
and modifying compounds and gravity separated to mostly generate secondary
bitumen
which can be reused in the industry.
Preferably, the second mix material is further purified by dehydration,
milled, and
mixed with volatile and modified compounds to generate a bitumen-wood fiber
mix.
Still preferably, the mechanical crushing of the asphalt based roofing
material, being
conducted in a cylinder-shaped rotor type impact extractor, comprising a
rotational
cylinder equipped with a plurality of non-sharpen impact members and a
separating
sieve.
According to yet another aspect of the invention there is provided an
apparatus for
cold separation of recycled asphalt based roofing material, said apparatus
comprises a
cylinder-shaped rotor type impact extractor with a rotational cylinder,
equipped with a
plurality of non-sharpen impact members and a separating sieve. Preferably,
the
separating sieve has a plurality of openings of about 3/4 inch while the
apparatus is
further comprising a mist generator. More preferably, said apparatus is
further
equipped with a separation drum and an air separator to separate said material
into a
first mix material comprising fine bitumen particles, a second mix material
comprising
bitumen particles with wood chips and third coarse mix material comprising
gravel.
According to yet another aspect of the invention there is provided a method
for
recovering bitumen from a recycled asphalt based roofing material, the method
comprising: utilizing the apparatus for cols separation listed above, to
separate the
first mix material from the recycled asphalt based roofing material, thermo-
dehydrating
said first mix material in thermal reactor, enriching said dehydrated mix with
volatile
compounds selected from the group of: organic and synthetic oil base materials
and
modifying compounds selected from the group of styrene-butadiene-styrene
polymers ,
and gravity separated from the secondary grade bitumen.
According to yet another aspect of the invention there is provided a method
for
generating bitumen felt mix, from a recycled asphalt based roofing material,
the
method comprising: utilizing the apparatus for cold separation listed above,
to separate
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the second mix material from the recycled asphalt based roofing material,
thermo-
dehydrating said second mix material in thermal reactor, enriching said
dehydrated mix
with volatile compounds selected from the group of: organic and synthetic oil
base
materials and modifying compounds selected from the group of styrene-butadiene-
styrene polymers, while milling it through siefer mill.
Further there is provided a process for recovering bitumen from a recycled
asphalt
based roofing material, the process comprising: utilizing the cold separation
apparatus
to separate the first mix material from the recycled asphalt based roofing
material,
thermo-dehydrating said first mix material in thermal reactor, enriching said
dehydrated
mix with volatile compounds selected from the group of: organic and synthetic
oil base
materials and modifying compounds selected from the group of styrene-butadiene-
styrene polymers , and gravity separated from the secondary grade bitumen.
Preferably, the thermo-dehydration process takes place in thermal reactor with
agitation
in the temperature range of 60-2500, preferably 160-200 co, more preferably at
about
180 co
According still another aspect of the invention there is provided a process
for
generating bitumen felt mix, from a recycled asphalt based roofing material,
the
process comprising: utilizing the apparatus for cold mechanical separation
mentioned
above, to separate the second mix material from the recycled asphalt based
roofing
material, thermo-dehydrating said second mix material in thermal reactor,
enriching
said dehydrated mix with volatile compounds selected from the group of:
organic and
synthetic oil base materials and modifying compounds selected from the group
of
styrene-butadiene-styrene polymers, while milling it through siefer mill.
Preferably, the
thermo-dehydration process takes place in the thermal reactor with agitation
in the
temperature range of 60-250 , preferably 160-200 C , more preferably at about
180
C .
These and other aspects of the invention would be apparent from the provided
description, examples and the claims.
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DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic diagram that describes a recycling process of old
roofing
materials.
Figure 2 is a schematic representation of first embodiment of a horizontal
cylinder-
shaped rotor type impact extractor.
Figure 3 is a schematic representation of a second type of horizontal cylinder-
shaped
rotor type impact extractor to carry out extraction of bitumen from
preliminary chopped
roofing materials.
Figure 4 is schematic representation of first embodiment vertical type oil-
jacketed,
heated reactor, equipped with agitator and tap-holes to separate release
recovered
secondary bitumen and mineral residue.
Figure 5 is schematic representation of second embodiment of vertical type oil-
jacketed, heated reactor, equipped with agitator and tap-holes to separate
release
recovered secondary bitumen and mineral residue.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The process for recycling roof material comprises several separation,
purification and
recovery processes. First the materials are being separated into bitumen
containing
materials and other rejected materials. The
bitumen containing materials are
mechanically separated into two material flows: bitumen crumbles and soaked
with
bitumen roofing felt. Each of these material flows, further dehydrated and
purified to
generate products useful in future applications. Such as commercial grade
bitumen,
bitumen emulsion and bitumen fiber mix.
One of the aspects of the invention is the cold separation of the recycled
materials:
unlike the method used in the art; the material should not be milled to the
homogeneous mix. The recycled material should be cut into relatively large
pieces and
these pieces should be mechanically destroyed by crashing, hitting, hammering,
with or
without assistance of the vibration. This way there is an increased chance
that bitumen
particles would be fully separated from the paper layers. This crashing by
hitting
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should be differentiated from simple crashing by cutting. This hitting would
solve the
problem of separation of bitumen from the paper. Therefore the hitting
apparatus
preferably have no sharp members, to reduce the chance of cutting material.
In alternative embodiment the separation apparatus may comprises combination
of
hitting, crushing and cutting members.
The invention is illustrated by the example set below. The data for this
example was
developed in the following manner, illustrated by the diagram in Figure 1.
Figures 2 and
3 schematically illustrate apparatuses used for cold mechanical crushing of
the roofing
material. Figures 4 and 5 schematically illustrate thermal reactors. It would
be apparent
to the person skilled in the art that other apparatuses can be used to perform
these
functions.
During a roof replacement, old roof was cut by segments with approximate size
3x3
feet (10). Further roofing membrane torn off and were sorted (11) by splitting
the
bituminous layers from the rigid wood fiber insulation. The bituminous roofing
scraps
were collected into waste containers and transported to outside storage for
further
reprocessing (12).
Cold separation step (12-16 in Figure 1)
Ready for reprocessing main roofing bituminous membrane, comprising plies of
roofing felt physically stuck together with mopped bitumen and compounded with
the
top layer of membrane gravel, was mechanically loaded into charging hopper and
continuously fed into a horizontal cylinder-shaped rotor type impact
extractor(13). The
impact extractor (30) illustrated in Figure 3 consists of a cylinder (36)
rotated with 500
rpm, comprising 20 appropriate sized non sharped impact teeth. During the
extraction,
the milled material was removed from the extractor out through screen (33)
through a
plurality of apertures with diameter 3/4", positioned at the bottom part of
the extractor
(30). This extracted milled mix comprises bitumen crumbs, roofing felt chips
and gravel.
To prevent balling of bitumen onto the rotated parts, the impact extractor was
equipped with a mist generating nozzles, spraying regular cold water into the
extractor
system.
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After exiting the rotor-type impact extractor, the resulting mix, comprises
bitumen
crumbs, roofing felt chips and gravel was continuously moved into through
conveyor
(34) to a drum separator. Drum separator is equipment well known in the art.
Said
drum separator (14) was equipped with a steel wire mesh with apertures of
1/8", allows
separating most of the bitumen crumbs as a First type of material (16) from
the loaded
milled mix. Second type of materials, with particle size larger than 1/8",
consist of
bitumen felt chips and gravel mix, was continuously removed from the drum
separator
through the end face. This Second type of materials was exposed to a
gravitational
separation along with pressured air separation. This double separation was
conducted
to split the roofing felt chips (15) as the light ends and the gravel (22) as
the tailing.
As the results of cold separation step, there were acquired three types of
segregated
materials: First mix (16) of bitumen crumbs fraction smaller than 1/8", which
was used
in manufacturing of commercial bitumen. Second mix (15) Bitumen felt chips
with size
above 1/8", which was used to produce various bituminous core products, for
example
to use in roofing and waterproofing applications. And commercial gravel
fraction with
size of about 3/8" - 5/8", that was can be used as-is in road, roofing and
construction
applications. Separated materials were stockpiled in different piles ready for
further
processing.
Dehydration step (18)
The bitumen crumbs, the First type of products acquired from cold separation
step,
were mechanically loaded into a vertical type stainless steel oil-jacketed
Mueller reactor
Illustrated in Figure 5 with working volume equivalent to about 2000 US Gal.
The
reactor (40) was equipped with an isothermal gas heating system (41) with
temperature range of 60 -250 C, a heavy duty mechanical agitator (43) and tap-
holes
(44) and (45). The reactor (40) was used to regenerated and separated release
recovered bitumen and residual bitumen fouled with mineral slurry.
The mass of loading batch depends on a capacity of reactor to be used. Process
of
dehydration was started at temperature of about 180 C with an intensive
mechanical
agitation and was conducted with foaming of the liquid bitumen. The agitator
was
periodically changed rotation from clockwise to counter clockwise. Intensity
of the
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agitation in that period was corresponded to about 30 rpm. Process of
dehydration was
continued until the majority of water was removed. The end point of
dehydration
process was visually indicated by discontinue of foaming and sudden increase
in the
temperature of liquid bitumen that was produced, along with appearing of white
smoke.
At this point of time the reactor was ready to receive next batch of the
bitumen crumbs.
Intensive mechanical agitation and temperature of 180 C were sustained during
the
full dehydration of loaded volume of bitumen crumbs. The temperature settings
were
adapted to a working volume of the reactor.
Bitumen recovery
When the maximum loading of the reactor was reached and dehydration process
was
completely finished, the liquid bitumen was further recovered by an injection
of volatile
and modifier compounds. In this example we used crankcase oil however any
organic
and synthetic oil base materials can be used as a volatile compound. The use
of
rejected oil was one of examples of further reduction of environmental impact.
The
volatile compound was injected in the range of about 4% by weight of loaded
bitumen
crumbs. SBS modification pellets were used as a modifier compound. Actually
any
modifying compound known in the art can be used fro example any styrene-
butadiene-
styrene polymer group even recycled plastic bags can be used as modifying
agent. The
SBS modification pellets were loaded into liquid bitumen in about 2% by weight
from
loaded bitumen crumbs.
After bitumen was recovered the agitation was continued for about 1 hour in
order
to acquire fully homogenous recovered bituminous solution. After 1 hour the
intensity of
the mechanical agitation was reduced to 10 rpm, the temperature was gradually
to
70 C in about 2 hours.
The recovered bitumen was maintained in the reactor at a temperature of about
70 C without mechanical agitation, to allow the fouled bitumen with mineral
slurry to
settle to the bottom of the reactor.
Consecutively, the substantially clean liquid bitumen (21) also known as
secondary
bitumen were collected from the reactor using an upper level tap-hole (44) for
packaging, or later processing. The residual of the fouled bitumen, along with
mineral
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slurry, was removed from the reactor through low level tap-hole (45) and after
crystallization was stockpiled for further processing. There was a low amount
of fouled
bitumen, since the main compound of first mix was bitumen crumbles.
Secondary product recovery (17)
Soaked bitumen roofing felt chips with size of above 1/8", that were derived
as a
second type of products from the cold separation step, were mechanically
loaded into a
to vertical type stainless steel oil-jacketed Mueller reactor with working
volume
equivalent 2000 US Gal. The reactor was equipped with an isotherm gas heating
system
with working temperature interval of about 60 -250 C, heavy duty mechanical
agitator
and tap-holes to release bitumen mix. The mass of loading batch depends on
capacity
of reactor to be used.
The process of dehydration was started at a temperature of about 180 C with
intensive mechanical agitation and was conducted with foaming of the liquid
bitumen.
The agitator periodically changed rotation from clockwise to counter
clockwise. Intensity
of the agitation in that period was corresponded to about 30 rpm. Process of
dehydration was continued until the majority of water was removed, that was
visually
indicated by halt of foaming and sudden increase of the temperature of liquid
bitumen
that was conducted, along with appearing of white smoke.
At this time the reactor was ready to load next batch of the bitumen felt
chips.
Intensive mechanical agitation and temperature of 180 C was sustained during
full
dehydration of loaded volume of bitumen felt chips. The temperature profile
was
adapted to the working volume of the reactor.
When the maximum load of the reactor was reached and dehydration process was
completely finished, the liquid bitumen mix was milled and smoothed by
continuously
pumping through siefer mill, simultaneously with injection of volatile and
modifier
compounds. Used/recycled crankcase oil was used as a volatile compound and was
injected in about of 3%-5% from loaded bitumen felt chips. SBS modification
pellets
were used as a modifier compound and were loaded to liquid bitumen/felt
mixture in
term of numbers of 1%-3% from loaded bitumen felt chips. After bitumen mix was
recovered the agitation was continued for about 1 hour for the purpose to
acquire fully
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homogenous bituminous-wood fiber solution. The recovered bitumen-wood fiber
mix
was used to produce various bituminous core products (19) to use in roofing
and
waterproofing applications. The mix can also be used to produce Bituminous
Mastics
(20).
The Tablel below roughly illustrates the mass balance of the process in the
example.
All numbers are provided in kg. This way a significant amount of secondary
bitumen
was recovered from the recycled roof material. The recovery rate of bitumen
was
almost 50% of the initial weight, and more than 80% of the bitumen was
recovered.
Many variations and improvements can be made to the current process to further
improve these numbers without departing from the concept of the invention.
Table 1 The Mass Balance :
Torn off and Cold separation step Dehydration and recovery step
preliminary Bitumen Soaked Gravel Bitumen Mineral bitumen-
sorted crumbs bitumen fouled wood fiber
bituminous roofing felt bitumen mix
membrane chips
1000 450+550 150+250 300 kg 400+500 20+30 150+250
It would be apparent to the person skilled in the art that many modifications
can be
made to the disclosure without departing from the scope of the invention. Thus
provided examples are presented as a sample and not in a limiting way.
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