3
estimated life is based on a typical design feed size distribu-
tion and operating within the specified parameters.
Most wear components should last for their estimated
life if the system is designed and operated well. However,
several operational factors can cause premature failure,
which requires additional monitoring systems and smart
design to minimize the likelihood of failure (Table 4).
IMPACT OF AVAILABILITY ON
EQUIPMENT SIZE
The impact of equipment availability on achievable
throughput is significant. Figure 1 presents an example of
the required instantaneous throughput by a primary jaw
crusher to maintain an annualized throughput rate of 6
Mt/y and operate with the close-side setting of 120 mm.
A low-availability crusher requires a higher through-
put target than a high-availability one. The correspond-
ing power draw for the crusher changes from high to low
depending on the required throughput. Thus, a crusher
with low availability will need to be larger to accommo-
date higher throughput, which will impact the capital cost
required for the project.
A low-availability crusher increases the capacities of all
bulk-handling equipment. Conveyors, transfer points, bins,
and coarse ore stockpiles must be sized and engineered for
the higher throughput and loads.
Figure 2 presents the minimum estimated coarse ore
stockpile (COS) size and number of dump trucks required.
Figure 3 highlights the required capital cost for the COS
and reclaim system based on the crusher availability. The
following assumptions were used in the calculation:
• An angle of repose of 37 degrees was used to deter-
mine the height and diameter of the COS to main-
tain the feed rate to the grinding circuit while the
crusher is offline for maintenance
• A dozer is used to maintain consistent feed to the
grinding circuit when the primary crusher is offline
• A CAT 793 dump truck with a rated payload capac-
ity of 240 t and cycle of 15 min per dump was used
as the means of haulage from the mine to the pri-
mary crusher
• Crusher dump pocket capacity has a live volume of
360 t (approximately x1.5 of one dump capacity)
• The coarse ore stockpile and reclaim systems costs are
based on Ausenco’s historical direct cost estimates.
Table 2. Summary of major components in process classifiers
and bulk handling systems
Classifiers (Screens &
Hydrocyclones)
Bulk Handling
(Conveyors, Feeders,
Diverter Gates,
Chutes)
Wear parts Screen panels, pump
wet ends, spigots,
vortex finders
Conveyor belts, skirts,
chute wear plates,
diverter gates, apron
feeder chains &plates
Mechanical Gears, shafts, bearings,
fasteners, gearboxes
Idlers, pulleys, gears,
shafts, bearings,
fasteners, gearboxes
Electrical Motors, control panels, wiring, exciters
Hydraulics Oil and filters, pumps, cylinders
Safety Guard rails, emergency stop buttons
Table 3. Approximate life of major wear components
Low Abrasive Ore High Abrasive Ore
Crushers 3 months 1.5 months
SAG mills 8 months 4 months
Ball mills 12 months 6 months
Bulk systems
(conveyors,
apron feeders)
+20 years +10 years
Bulk systems
(chutes and
skirts)
2–5 years ~1–2 years
Hydrocyclones
and pumps
Cyclones 1 month
Pumps 2 months
Cyclones 0.5
months Pumps 1
month Table 4. Cause of premature failure of wear components and
recommended solutions
Equipment Failure Solution
Crushers Liner and
mechanical failure
due to tramp metal
(or media) in the ore
feed
Install metal
detectors and
magnets on
conveyors on
secondary and pebble
crusher systems
Mills Liner failure caused
by high media
impact
Install mill acoustics
and optimize liner
design and process
control
Hydrocyclones
and pumps
Coarse media in
cyclone feed
Install trommels/
discharge screens or
trommel magnets at
the end of SAG and
ball mills
Conveyors Misalignment of
conveyors and
belt-tear caused by
coarse-angular feed
Proper design of
transfer points and
install belt tracking
sensors
estimated life is based on a typical design feed size distribu-
tion and operating within the specified parameters.
Most wear components should last for their estimated
life if the system is designed and operated well. However,
several operational factors can cause premature failure,
which requires additional monitoring systems and smart
design to minimize the likelihood of failure (Table 4).
IMPACT OF AVAILABILITY ON
EQUIPMENT SIZE
The impact of equipment availability on achievable
throughput is significant. Figure 1 presents an example of
the required instantaneous throughput by a primary jaw
crusher to maintain an annualized throughput rate of 6
Mt/y and operate with the close-side setting of 120 mm.
A low-availability crusher requires a higher through-
put target than a high-availability one. The correspond-
ing power draw for the crusher changes from high to low
depending on the required throughput. Thus, a crusher
with low availability will need to be larger to accommo-
date higher throughput, which will impact the capital cost
required for the project.
A low-availability crusher increases the capacities of all
bulk-handling equipment. Conveyors, transfer points, bins,
and coarse ore stockpiles must be sized and engineered for
the higher throughput and loads.
Figure 2 presents the minimum estimated coarse ore
stockpile (COS) size and number of dump trucks required.
Figure 3 highlights the required capital cost for the COS
and reclaim system based on the crusher availability. The
following assumptions were used in the calculation:
• An angle of repose of 37 degrees was used to deter-
mine the height and diameter of the COS to main-
tain the feed rate to the grinding circuit while the
crusher is offline for maintenance
• A dozer is used to maintain consistent feed to the
grinding circuit when the primary crusher is offline
• A CAT 793 dump truck with a rated payload capac-
ity of 240 t and cycle of 15 min per dump was used
as the means of haulage from the mine to the pri-
mary crusher
• Crusher dump pocket capacity has a live volume of
360 t (approximately x1.5 of one dump capacity)
• The coarse ore stockpile and reclaim systems costs are
based on Ausenco’s historical direct cost estimates.
Table 2. Summary of major components in process classifiers
and bulk handling systems
Classifiers (Screens &
Hydrocyclones)
Bulk Handling
(Conveyors, Feeders,
Diverter Gates,
Chutes)
Wear parts Screen panels, pump
wet ends, spigots,
vortex finders
Conveyor belts, skirts,
chute wear plates,
diverter gates, apron
feeder chains &plates
Mechanical Gears, shafts, bearings,
fasteners, gearboxes
Idlers, pulleys, gears,
shafts, bearings,
fasteners, gearboxes
Electrical Motors, control panels, wiring, exciters
Hydraulics Oil and filters, pumps, cylinders
Safety Guard rails, emergency stop buttons
Table 3. Approximate life of major wear components
Low Abrasive Ore High Abrasive Ore
Crushers 3 months 1.5 months
SAG mills 8 months 4 months
Ball mills 12 months 6 months
Bulk systems
(conveyors,
apron feeders)
+20 years +10 years
Bulk systems
(chutes and
skirts)
2–5 years ~1–2 years
Hydrocyclones
and pumps
Cyclones 1 month
Pumps 2 months
Cyclones 0.5
months Pumps 1
month Table 4. Cause of premature failure of wear components and
recommended solutions
Equipment Failure Solution
Crushers Liner and
mechanical failure
due to tramp metal
(or media) in the ore
feed
Install metal
detectors and
magnets on
conveyors on
secondary and pebble
crusher systems
Mills Liner failure caused
by high media
impact
Install mill acoustics
and optimize liner
design and process
control
Hydrocyclones
and pumps
Coarse media in
cyclone feed
Install trommels/
discharge screens or
trommel magnets at
the end of SAG and
ball mills
Conveyors Misalignment of
conveyors and
belt-tear caused by
coarse-angular feed
Proper design of
transfer points and
install belt tracking
sensors