UNDERGROUND RAIL
Rail-Veyor versus conventional rail
Jim Fisk at Rail-Veyor made his arguments for its design over conventional
rail in mining to IM: “With conventional rail (CR), the gradient needs to be
at most about 3%, or relatively flat. Mines will refer to these drifts
sometimes as horizons because of that feature. Rail-Veyor can work from 0-
30% incline with about 18% being the steepest that workers doing
maintenance would want to walk up or down. At about 25%, there is the
issue of material roll-back.” This steeper gradient means in a new mine or
new development within an existing mine, the amount of material which
needs to be moved in order to get to the ore body is much less with RV
meaning major cost savings. The Rail-Veyor system can haul up to 250 t per
train with the haul rate design based on the customer’s requirements.
He adds: “CR uses distinct carts with gaps between. They weigh much
more than the RV system which uses cars in a continual line. Think of a
segmented snake. The overall weight of the RV train has been engineered
to be as light as possible while still being heavy-duty enough to have
material dumped into it while it is moving and maintaining a 20-year life
expectancy. CR has about a 24 t per axle load with two rigid axles. Compare
that to RV with a 1 t load split axle for greater movability. The RV train car
has only two wheels (except the front car) much like the concept of a boat
trailer. While the frames are basically standardised, the cars themselves
can be designed for the individual mines. Shorter, wider, or taller car
designs allow the mine to optimise the haulage based on the material to be
moved. Because the cars can be designed for the mine (or the mine
designed for the system), RV curvature can be tighter. Typically, CR is
limited to about 60 m radius and RV can go as tight as 30 m.”
CR also uses a heavier grade of track due to the weight of the entire
system. “Much more construction goes into CR infrastructure because of
that weight. We’ve engineered as much weight out of the haulage system
as we can, so the track is lighter and only needs to handle about 8 pounds
per square inch. It’s about the same amount of pressure as standing on one
foot. For propulsion, CR typically has a small locomotive engine to move the
train. This can be diesel, overhead electrical, or battery. With diesel, you
have the same particulate matter as with trucks and thus the same
ventilation issues. With manpower, it is the dependent upon a healthy and
strong workforce. RV does not have an engine on the front or back of the
train to move it. Instead, it relies on drive station technology whereby
motors and gearboxes cause tires to move together to propel the train
forward like the speed booster on a toy racetrack. At least one drive station
has contact with the RV system at all times. Not only is this used for
propulsion, but also for braking. There is no diesel particulate matter and
no need for extensive ventilation shafts. The RV system is electric but the
source of the electricity is up to the mine. There is no dedicated operator
for the system. It is not ‘remote controlled’ or one operator per train. It is
truly autonomous and is controlled by a software program which takes into
account tons to be moved, speed to move, number of cars in the train,
number of trains in the system, etc. Some mines choose to use someone
running another piece of equipment to monitor the system which is also
self-regulating. It will let the monitoring personnel know if there is an issue
with the system with an alert to a tablet or desktop computer system.”
Re: loading – CR has distinct carts, and thus the loading is a constant
start and stop with each cart needing to be loaded. Depending on the
loading mechanism, there may be an issue of spillage due to the gap
between each cart. “With RV’s continuous trough design, loading does not
have to start and stop for each car. Instead, the entire train is loaded.
Typically, the end of the loading chute is inside the trough so there is no
spillage over the sides. This makes the loading process much faster. RV
loads at a slightly slower speed than its tramming speed. Because of this,
an empty train (having returned from discharging material) will be waiting
to be loaded as soon as the one before it is done. The same issue with
loading occurs with unloading. The carts, either individually or in small
groups, are inverted to dump the material out. With RV, the material is
literally thrown out of the car. Even wet muck is rarely retained in the cars.”
Shown is a 'light fence' that determines if there is any protruding
material which would cause issues at the numerous drive stations (seen
in the background) which both propel and brake the Rail-Veyor train. The
segmented nature of the trough allows for continuous loading and
discharging while permitting the train to go around significantly tight
curves
based in Xiangtan which is a centre of electric
drive technology in China and both make their
own electric motors and have both built lithium
battery locos already for the mining market. This
includes lithium battery locos developed as part of
a collaboration between XEMC, Hunan Yutong and
Chinese rail equipment giant CRRC which also has
a large division supplying diesel and electric
mining rail solutions. The new locomotives
included a 2.5 t, 5 t and 8 t model all with lithium
batteries. These have been delivered to mining
companies including several operations of
Shandong Gold in Shandong Province as well as in
Inner Mongolia. A 15 t loco with lithium battery
has also been designed by Hunan Yutong for a
copper mine in Zambia. XEMC has also developed
its own lithium battery locos for several projects.
Aside from these OEMs there are two major
engineering companies that are leading the
developed of autonomous mining rail both in
China and in some overseas projects, namely
China ENFI, part of MCC, and Beijing Soly
Technology which is also one of China’s major
suppliers of FMS solutions to open pit mines and
is ultimately part of iron and steel group
Shougang. A third group, China Nerin Engineering,
is also involved in this market.
One of the first successful installations came in
2015 when China ENFI completed the last test on
the control system for unmanned electric
locomotive transportation in the Dongguashan
copper mine of Tongling Nonferrous Metals Group
Holding in Anhui province. The system consists of
an intelligent unmanned variable-frequency
electric locomotive, roadway mobile wireless
communication system, automatic dispatching
system for electric locomotive, protection and
monitoring system and electric locomotive
transportation power supply control system. The
electric locomotive traction train achieves remote
ore loading, automatic operation and ore
unloading. Its operating status is displayed in the
dispatching room in real time via wireless
communication, and it can be controlled through
remote real-time dispatching if necessary. At this
mine the system allowed a reduction in the
number of workers from 40 to 8 in the
transportation system. ENFI also estimates its
working efficiency is 25% higher than that of the
traditional transportation mode.
China ENFI went on to sign a contract in 2016
26 International Mining | JUNE 2020