“THE CASSIAR STORY”

The Tramline

Peter C. Jones, Plant Superintendent,
Cassiar Asbestos Corporation Limited,
Cassiar, B.C.

Abstract

Owing to the inadequacy of the ore transport system at
Cassiar in the late 1960's, a new facility was required. This
paper traces the various alternatives considered and gives
a description of the tramline as installed. The problems
encountered, changes made and future modifications are
discussed in detail, together with the effects these have on
maintenance and operations.

Introduction

IN 1971, owing to the increased production and in-
adequacy of the present system, a study was started on
the best method of transporting ore the 3 miles (4.8
km) between the mine and mill. At that time, a Breco
continuous bi-cable tramline was being used. However,
its 100-tons-per-hour capacity, which had been more
than sufficient at its installation in 1956, was in-
adequate and was having to be augmented by trucking.

Included in the study were possible changes in the
crushing and concentration plant, which were then
situated at the mine site (Fig. 1).

Three basic proposals were considered, together with
their variations: a new tramline, a conveyor and truck-
ing. For each proposal and variation, estimates were
made of capital and operating costs and estimated rate
of yield over a 16-year life (Table 1).

After further study, it was decided that the design
parameters should be for an ore mining rate of
1,200,000 tons per year, with the concentrator at the
mill. This would allow for a steady drier feed, resulting
in increased drier efficiency. On this basis, a closer
cost study was undertaken.

The conveyor-belt option was rejected on the basis
that its capital cost was too high and the amount of
ore to be moved would be too low to take advantage
of this method of high-volume delivery. The local topo-
graphy also ruled against a conveyor.

Peter C. Jones was born in England in
1947, and received his early education
in England and later in Wales. In
1968, he graduated in electrical en-
gineering from Rugby College of En-
gineering. His early career was as a
student engineer in nuclear power
plant construction. From 1969 to 1972,
he worked as assistant engineer and
“8 section engineer for Anglo American
= Corporation in Zambia in both under-

ground and open-pit operations. Since
coming to Canada in 1972, he has worked for Newmont
Mining as electrical superintendent and plant superinten-
dent at the Grandue operation and later as plant super-
intendent at the Similkameen copper mine.

Mr. Jones is currently plant superintendent at Cassiar —
errs he has held since joining the company in late

Keywords: Cassiar Mine, Asbestos, Transportation, Tram-
lines, Loading, Ropes, Wire ropes, Cables.

Four tramline companies were asked to submit
proposals. Of these, two were for two-section tramlines
similar to the existing system and the tramline at
Cassiar Asbestos Corporation’s Yukon property at
Clinton Creek, one was for a single-section tramway
using two track ropes and the fourth was for a single-
section tramway of new design utilizing two track
and two haul ropes.

One of the two-section tramlines was rejected on the
basis of delivery, and the fourth proposal was rejected
because it was an untried design. The final choice
was therefore between two tramlines and trucking
(Table 2).

As can be seen, both tramlines offered considerable
savings over trucking, with the single-section Inter-
state proposal showing the best rate of yield. In Feb-
ruary, 1974, an agreement was signed with Interstate
Equipment Corporation to supply an aerial tramway
system (Fig. 2).

The system would transport ore in 142 cars at 300
tons per hour over a slope distance of 15,370 ft
(4685 m) and a vertical distance of 2130 ft (650 m).

Drive was to be D.C. thyrister controller to allow
easy slow-speed starting and variable speed for in-
spection and maintenance. Prior to starting fabrica-
tion, the drive was changed because during detailed
engineering it was realised that the voltage swings
caused by shovels in the pit combined with this drive/
regenerative application would lead to a frequent
blowing of the thyrister protection fuses or the thy-
risters themselves. The choice then was between a
more expensive Ward-Leonard control system or an
induction motor drive with a separate pony motor for
slow-speed operation. As commissioned, the drive con-
sisted of two 300-hp 550-volt 900-rpm induction motors
driving dual-input shafts of a Falk gear reducer, one
motor being designed to start on reduced voltage. The
driveshaft of the gear reducer drives a 188-in.-diame-
ter drive wheel at 12.45 rpm, giving a tramline speed
of 600 fpm. Spring-loaded grips on the drive wheel
grip the tramline haul rope, thus transmitting the
drive during starting and the required braking during
full-loaded running. Emergency and service braking
are provided by two brake bands acting on the drum —
similar to many shaft hoists. Tension is kept in the
haul rope by using a weighted travelling truck-type
constant tension unit at the discharge. This moves a
total of 20 ft (6.1 m), giving 40 ft (12.2 m) of take-up.

A 75-hp pony motor was fitted for 100-fpm running
and initial starting. This suffered from several disad-
vantages. For maintenance, the fixed-speed operation
led to extended time for greasing, as the cars moved
at a slow pace and full start-up procedures had to be
followed after every stop. Worse still, after prolonged
shutdown of the system in sub-zero weather the pony
system would not provide sufficient torque to move the
tramline. On at least one oceasion, the tramline had
to be towed with a ‘Cat’ and the buckets manually filled
until the tramline had sufficient inertia to be started.

These problems eventually led to the design and
installation of an hydraulic pony motor drive in 1977.
In this system, two hydraulic motors power shaft
extensions on the motor via air-operated clutches. The
hydraulic system brings the tramline up to about 180
ft/min. (24.4 m/m), at which time the main motors
are started and the clutches disengage the hydraulic

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