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Capacity
requirements, disappearing skills drive Walker crusher change
By Andy Bateman,
Engineering Editor
Increased
capacity requirements and the loss of operator skills through retirement
prompted Walker Industries' recent decision to change a vintage primary
crusher at its Thorold, Ont. quarry.
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This
year's winter maintenance program at the Thorold limestone operation
included the replacement of its 1946 primary jaw crusher, bought by
Walker in 1955 and in continuous service there ever since. The crusher
performed well over that time, but had become the bottleneck in the
system as a result of other improvements. In addition, dated design
features such as water cooling and Babbit bearing surfaces translated
into high repair costs to maintain an acceptable level of availability.
Ed Lamb, director of Aggregate Operations, adds that the approaching
retirement of quarry lead hand Antonio Bevilacqua was another important
factor driving the change. Bevilacqua has poured replacement Babbit
for the jaw on numerous occasions and his 38 years of acquired knowledge
of the craft would be hard to replace.
A review of quarry files revealed that
the old crusher, a 48x60 Allis-Chalmers double-toggle jaw, weighed just
over 98 tonnes complete, or some 43 per cent heavier than its 68.5 tonnes
replacement. At one point it was thought that the jaw might be removed
in a single piece, but it was later decided to simplify the lifting
job by making three separate lifts; swing jaw first, followed by flywheels
and toggles and then a final lift for the frame. As the exact weight
of these components was uncertain, contractor Vic Powell & Sons Welding
Ltd. brought in two Grove TM800 80-tonne capacity mobile cranes to remove
the old crusher, keeping one TM800 on standby. Other precautions included
scheduling all the heavy lifts for a Saturday, so that power to nearby
overhead lines could be turned off. Four weeks later, the heavy lifting
for the replacement crusher was completed utilising a Krupp 100-tonne
capacity mobile crane. Thanks to this good planning, the heavy lifts
themselves proved uneventful.
Lamb expects that the new 47x63 Metso
C160 single-toggle (overhead eccentric) jaw crusher will increase primary
capacity by 20 per cent, based on the same feed and product sizes of
900 mm minus and 250 mm minus, respectively. Other changes being completed
in tandem with the crusher change include a new feeder and improvements
to access beneath the crusher. The new 1.53 m wide by 7.3 m long Simplicity
vibrating grizzly feeder will utilise the same framework as its 1972
1.53 m wide by 6.71 m long Simplicity predecessor, with the extra 600
mm in length being accommodated by extra cantilever. Underneath the
crusher, a new concrete retaining wall provides improved access to the
crusher and take away belt.
Back on the topic of job planning, Lamb
notes that Thorold's normal March-April maintenance shutdown was put
back a month to ensure the necessary replacement parts were to hand
and that the outdoor work might be done in reasonable conditions Æ a
good move in light of Southern Ontario's challenging March weather!
Walker Industries Holdings Ltd. - Aggregates
& Construction Group, is based at the Thorold quarry.
A 100-tonne
capacity Krupp mobile crane carefully lifts the 23.8 tonne Pitman of
Walker's new 47x63 Metso C160 primary jaw crusher into place.
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| The
frame of Walker's new Metso C160 primary jaw is prepared in readiness
for the cursher's Pitman. |
The
flywheels and toggles of Walker's 57-year old primary crusher, a
48x60 Allis Chalmers double toggle jaw, are removed by an 80-tonne
capacity mobile crane. |
May/June 2003 issue
Aggregates
and Roadbuilding Magazine
4999 St Catherine Street West. Suite 315
Westmount, Quebec H3Z 1T3
Tel: (514) 487-9868 Fax: (514) 487-9276
EMail: rocktoroad@sympatico.ca
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