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thereby pulverising hard materials and tearing softer
materials into a fluff, creating a smaller output than
traditional shredding equipment. Material is reduced
to ±½ in. particles, a proprietary size and shape
that was determined by computational fluid dynamic
analysis to be optimum for the kiln at St Marys.
From the pulverizer, the material is conveyed
via the output conveyor to a waiting walking‑floor
truck, which takes it to the cement plant. The output
conveyor includes a cross-belt magnet to detect
those smaller pieces of metal that have made it
through the process. “The last thing you need in
a wood sliver that is going to be used as fuel in a
highly-controlled process is a metal foreign object,”
said Bowers.
The output end of the equipment also includes a
number of dust management processes, as “there
is significant airflow inside the pulverizer; therefore,
there’s a lot of particles entrained in the air [on the
output side] and that air-particle combination needs
to be managed,” explained Bowers. This is done via
a box-covered conveyor located immediately at the
pulverizer exit, which allows the air‑entrained particles
to drop back down into the material flow. Air is also
drawn off from the covered conveyor into a baghouse,
where very fine sawdust is recovered and forms part
of the product shipped to the St Marys plant.
The new plant layout, processing, line, and system
was conceived and designed by Nicolas Belanger,
Executive Vice President North American Sales,
who brings over twenty years of waste equipment
experience to TORXX.
The benefits of the system
In Bowers’ succinct summary, the system allows
St Marys Cement to “receive waste wood for
their purpose, which is roughly 100 tpd, on a
just‑in‑time basis, from a location close enough
to their cement plant that makes it economically
viable, through a system that is very robust in
which large pieces of waste wood, received as is,
can be reduced in size in one pass.”
These features provide the key benefits of
reliability and efficiency, as well as providing the
tonnes per hour of product the cement plant needs.
The system is also flexible: the one‑size‑fits‑all
pulverizer is used to reduce a wide range of waste
products from asphalt shingles, municipal solid
waste, compost, glass, and light cement products.
“The TORXX Kinetic Pulverizer has a 500 hp.
motor,” explained Bowers. “By slowing down or
speeding up this motor – and therefore the vertical
shaft – the customer can use the same piece of
equipment to reduce material of any type. It’s
very versatile. This was another key benefit for
St Marys Cement, as it offers the opportunity to
easily diversify the waste steams used to create
the alternative fuel product.
“We watched the machine in operation,” said
Ruben Plaza, Corporate Environmental Manager
for Votorantim Cimentos North America. “It
is strong and dependable. In one pass, the
TORXX Kinetic Pulverizer can give us the fuel
sizing we need. Shredders have high maintenance
costs; lower throughput for this size; and
cannot handle foreign metal objects, such as
nails, nuts, and bolts. Metal breaks teeth and
hammers and then you have downtime. The
TORXX Kinetic Pulverizer can address this and
the same machine can be used for other waste
materials, which is a benefit to the users.”
Co-processing and low-carbon fuels in
North America
Alternative, low-carbon fuels are a key pillar
of the cement industry’s drive to reduce its
environmental impact – but North America lags
behind Europe in uptake. For example, in Ontario,
usage is limited by environmental permit to a
maximum of 100 tpd. According to Plaza, the
St Marys plant in Bowmanville is among the first
in Ontario to get approval for wood fuel, reflecting
the company’s sustainability commitment and
strategies to address emissions and the reduction
of greenhouse gases.
“Generally speaking, Europe is ahead of
North America, although we count ourselves
among the North American companies proactively
seeking solutions to this global challenge,” said
the St Marys environmental manager. “For our
industry, there are opportunities for environmental
improvements from co-processing and the use of
alternative, low-carbon materials that are proven
to be effective as fuels, and can be made available
on a consistently reliable basis.”
To take alternative, low-carbon fuel to the next
level, an ECA is required, which can take several
years to obtain, although the Canadian government
is making great progress in reducing that
timeframe, as part of its focus on sustainability.
“It’s possible that the approach can
be replicated at other plants throughout
North America,” said Plaza. “St Marys will
continue to explore co-processing and the use
of other alternative, low-carbon fuels that would
otherwise be headed to landfills as another way to
reduce environmental impacts.”
Bowers is also positive about the growth of
alternative fuel use in North America: “We are
talking with several major cement plant companies
and discussing alternative, low‑carbon fuels,” he
said. It does, however, seem likely that the industry
will see more installations similar to that at the
McPherson transfer station in the near future, as
the use of low‑carbon fuels and greenhouse gas
reduction is a priority in this and other industries.
Note
TORXX Kinetic Pulverizer is a registered trademark of
TORXX Kinetic Pulverizer Ltd.
32
World Cement
North America 2019