UNDER THE GROUND
MINING: HIGH
SOLIDS REQUIRE
REPLACEABLE
OR HIGH
PERFORMANCE
VALVES
BY CRAIG BEKINS
Today, when we discuss the mining industry, it’s hard not to picture a
massive explosion ripping apart the side
of a mountain, the remnants of which
are then removed using the largest loaders and trucks imaginable. For the valve
industry, however, the interesting
processes happen after the ore has been
separated.
To gain a “valve” perspective, we
must first focus on the differences
between mining materials for construction and mining for industrial uses. The
majority of mines produce aggregates
for the construction segment. As such,
most of them have little or no application for industrial valves. A smaller
number of mines are used to get materials for facilities that produce industrial
products, so they seek coal, iron ore,
copper, nickel, gold and other resources.
The common denominator in the processing of such industrial minerals is a
moderate to high level of solids. This
requires either a low-cost design that
can be replaced regularly or a very
robust design that can withstand the rigors of solids-laden applications for an
extended period of time.
VALVE TYPES USED
IN MINING
Valves with soft replaceable sealing ele-
ments are relatively inexpensive to pro-
duce and repair and are commonly used
in processes where the operating temper-
ature is less than 375º F (190º C) and
where the pressure is relatively low (Class
300 max). Examples used in mineral
processing are rubber-lined knife gate
valves and butterfly valves as well as
sleeved plug valves. In these designs,
a soft sacrificial material provides tight
shut-off, but the resilient material is
quickly worn by the erosive slurry pass-
ing through the valve, and it is not
uncommon for valves of this type to be
repaired or replaced on a weekly basis.
Ore from the Goro Nickel Project in the South Pacific island of New Caledonia is processed at this remote plant.
plant. The application involves mixing
the ore with water to create a slurry
that is carried through a high-pressure
pipeline to its destination. These slurry
pipelines can range in size from six to
24 inches in diameter and in some cases
can be over 100 kilometers long. In this
application, valves are most commonly
used to isolate the pumps that are
tasked with keeping the slurry moving.
In doing so, the valves are exposed to
high pressure and a significant amount
of solids. This requires specific features
such as super-hard coatings on the interior surfaces of the valve to resist the
erosive forces of the high flow or high
differential pressure slurry and heavy-duty drive trains to ensure that the valve
does not seize despite the high level of
solids inherent in this application.
Slurry pipelines operate at ambient
temperatures and have little to no corrosive media. Therefore, valves for this
application can be made from carbon
steel and other relatively standard
materials. Valves in the slurry pipeline
