Fixed plant maintenance on a mine site: strategies, shutdowns, systems and the work that keeps it running
Fixed plant runs continuously, wears by the tonne and can only be opened up when it stops, which makes its maintenance a different discipline from the mobile fleet. How to choose a regime for each kind of equipment, why the shutdown calendar is the real schedule, how wear parts and spares are managed, and the systems and measures the work depends on.
Key takeaways
- Fixed plant is the crushing, screening, grinding, separation and materials handling equipment that stays where it is built. Its maintenance is shaped by continuous duty, abrasive material and the fact that most of it can only be worked on when the plant stops.
- No single regime suits a whole plant. Condition monitoring fits equipment that gives warning, fixed intervals fit wear that follows tonnes, and run to failure is a legitimate choice for low consequence items. Criticality decides which is which.
- The shutdown calendar is the real master schedule. Most fixed plant work is either shutdown work or the work that makes the next shutdown shorter.
- Wear parts, liners, idlers and screen media are where the money goes. Managing them is a supply and change-out problem as much as a maintenance one.
- The systems matter: an asset hierarchy built to ISO 14224, failure codes people actually use, and condition data joined to the work order history are what turn maintenance into a learning loop.
Fixed plant is everything on a mine or processing site that stays where it was built: the primary crusher, the screens, the conveyors and transfer chutes, the mills, cyclones, flotation cells, thickeners and filters, the stackers and reclaimers, and the pumps, motors and gearboxes that drive them. Fixed plant maintenance is the work that keeps that equipment running at rate, and it is a different discipline from maintaining a mobile fleet.
The difference comes from three things. The plant runs continuously, so most of it can only be opened up during a planned stop. It handles abrasive, often wet material, so wear is the dominant failure mode and it follows tonnes rather than hours. And it runs as one connected train, so a failure on a single feeder or conveyor stops everything downstream of it.
This guide covers what fixed plant maintenance includes, how to choose a regime for each kind of equipment, why the shutdown calendar is the real schedule, how wear parts and spares are managed, the systems and data the work depends on, and the measures that tell you whether it is working.
Fixed plant and mobile equipment are maintained differently
Most mining maintenance organisations split along this line, and for good reason. The two kinds of equipment fail differently, are accessed differently and are planned differently. A strategy that works for a haul truck fleet, where the manufacturer's service schedule and hour meter do most of the thinking, produces too little and too late on a processing plant.
| Fixed plant | Mobile equipment | |
|---|---|---|
| Duty | Continuous, as one connected train | Intermittent, one machine at a time |
| What drives wear | Tonnes handled, material properties, moisture | Engine and operating hours, haul profile |
| Where it is maintained | In place, often at height or in confined space | In a workshop, on a service bay |
| Effect of a failure | Stops the circuit downstream, often the whole plant | One unit down, the fleet keeps working |
| Strategy source | Site analysis of failure modes, wear life and criticality | Manufacturer schedules, adjusted from component life data |
| Intervention window | Planned shutdowns, with online work between them | Service intervals, with the machine swapped out |
On fixed plant a failure is rarely one machine's problem. The question is always what stops when it stops.
What fails, and how it fails
Fixed plant failure modes group by equipment family, and each family tends to have one dominant mode. Knowing which one applies is what makes a strategy sensible rather than generic.
- 1Primary crusher. Liner and mantle wear by the tonne
- 2Screen. Media wear, then deck fatigue
- 3Mill. Liner wear sets the reline, bearings give warning
- 4Cyclones and pumps. Slurry wear on the wet end
- 5Thickener. Rake drive and the instruments that hold the window
- Crushers: liner and mantle wear that follows tonnes and ore hardness, with bearing, hydraulic and lubrication failures underneath it.
- Screens: media wear and blinding, then fatigue cracking in the deck frame and side plates, and exciter bearing failure.
- Conveyors: idler and pulley bearing failure, belt cover wear and edge damage at the load points, splice failure, and chute blockage and spillage that trace back to flow rather than the conveyor.
- Mills: liner and lifter wear that sets the reline interval, trunnion bearing and gearbox condition, and lubrication system faults.
- Pumps and cyclones: wet end wear from slurry, seal failure, and cyclone liner wear that drifts the cut point before anything is visibly wrong.
- Thickeners, filters and reagent systems: rake drive and torque problems, cloth and membrane life, and the instrumentation that keeps the process in its window.
- Drives and electrical: motor bearings and insulation, variable speed drive cooling, and the protection and interlocks that fail hidden until they are needed.
Choosing a regime for each asset
A plant with thousands of maintainable items cannot carry a bespoke analysis for each one, and it should not try. The approach that holds up is to rank criticality first, then spend analysis effort where consequence justifies it and use templates everywhere else. Within that, the regime for each failure mode follows from how the failure behaves.
| Regime | Where it fits on fixed plant | What it needs to work |
|---|---|---|
| Condition monitoring | Bearings, gearboxes, motors and pumps that give measurable warning: vibration, temperature, oil condition, motor current | A P-F interval long enough to plan inside, alarm limits set per failure mode, and a work process that acts on the alarm |
| Fixed interval replacement | Liners, screen media, idlers, cyclone and pump wet ends, belt cleaners, where wear follows tonnes | Measured wear rates, a tonnage or runtime counter in the CMMS, and spares scheduled against the interval |
| Inspection | Structures, chutes, belts and guards, where the condition is visual and the defect grows slowly | A route, a checklist with pass and fail criteria, and defects that become work orders rather than notes |
| Failure finding | Protection, interlocks, trips and standby equipment, where failure is hidden until demanded | A test interval derived from the acceptable probability of the protection being unavailable |
| Run to failure | Low consequence items with a spare on the shelf and a quick change-out, where prevention costs more than repair | An honest consequence assessment, and a spare that is actually there |
Run to failure is a decision, not a default. The failure is when nobody made it.
The shutdown calendar is the real master schedule
On fixed plant, most of the heavy work is either done in a shutdown or exists to make the next shutdown shorter. The reline, the screen deck change, the belt splice, the crusher mantle, the thickener rake inspection: none of it happens while the plant runs. So the maintenance strategy and the shutdown strategy are the same thing seen from two sides.
The cycle is set by the longest-lived task that is shutdown bound, and the shorter-lived work is grouped underneath it. A plant that runs a four-weekly stop for screen media will fit idler changes, chute liner work and inspections into the same window, and hold the mill reline for the quarterly event. Where the cycle is set by habit rather than wear life, the plant either stops too often or runs parts past their life, and both cost tonnes.
The work between shutdowns matters just as much. Online condition monitoring, lubrication routes, belt and chute inspections and wear measurement are what turn a shutdown scope from a guess into a list, and a scope that is firm before the freeze is the difference between a shutdown that finishes on time and one that grows on the day.
- Freeze the scope at a fixed point before the event, and treat additions after the freeze as break-in work that needs a reason.
- Measure every wear part before the freeze, so the scope rests on wear rates rather than on the last shutdown's list.
- Pre-assemble and stage what can be, so the critical path inside the window is lifting and bolting rather than finding.
- Review scope growth and duration against plan after every event, and feed the wear data back into the intervals.
Wear parts, liners and spares
Wear parts are where fixed plant spends its money, and they are a supply problem as much as a maintenance one. Liners, screen media, idlers, belt and pump wet ends have lead times, and some are made to order. A site that discovers a long lead item is needed at the pre-shutdown inspection has already missed the window.
The useful discipline is to treat each wear part as a component with a life, a measured wear rate and a bill of materials link to the equipment it serves. Then the interval, the purchase and the shutdown scope all come from the same number. Insurance spares, the large and slow items such as a gearbox, a pulley or a mill motor, are a separate decision made on consequence and lead time, and the cost of downtime is the figure that makes that decision honest.
Change-out practice matters too. Standard component change-outs, with the removed item repaired off line, keep the shutdown short and move the repair out of the critical path. That needs a pool of spares and a repair loop, both of which have to be planned and funded rather than assumed.
A wear part without a measured life is a surprise waiting for a shutdown to happen in.
The systems the work runs on
Fixed plant maintenance generates a lot of data, and whether it becomes knowledge depends on the structure it lands in. The asset hierarchy is the foundation. Built on the ISO 14224 taxonomy, it puts every maintainable item at a level where its history can be found and compared, and it is what lets a site ask which screens fail most, or how liner life differs between crushers.
The CMMS or EAM holds the maintenance plans, the work orders, the failure codes and the history. Failure codes only earn their keep when the list is short enough that tradespeople use it honestly, and when someone reads the result. The historian supplies runtime, tonnes and process conditions, which is what lets intervals run on tonnes rather than calendar days and lets a failure be read against the conditions that preceded it.
Condition monitoring sits between the two, and it is only useful when its alarms become work orders that get planned and done. A monitoring program that produces reports nobody acts on is a cost, and the design of the action loop matters more than the sensors.
Measures that tell the truth
Fixed plant has one advantage over mobile fleet when it comes to measurement: the control system already knows when it ran, at what rate, and when it stopped. Availability and utilisation can be read from the historian rather than from a shift log, and the lost tonnes behind each stop can be allocated to a cause.
- Plant and circuit availability, measured from control system data against the constrained circuit rather than the average of every item.
- Planned maintenance compliance and schedule compliance, with break-in work tracked separately so planning drift is visible.
- Backlog in crew weeks, by criticality, so the number means something.
- MTBF for the repeating failure modes on critical equipment, which is where a reliability engineer's time pays back.
- Shutdown duration and scope growth against plan, event by event.
- Wear life achieved against planned life for liners, media and idlers, which is the number the intervals should be corrected from.
- Maintenance cost per tonne, split between wear parts, labour and contractors.
Measure the circuit that constrains the plant. Averaging availability across every item flatters the number and hides the bottleneck.
Standards and reference points
There is no single fixed plant maintenance standard. The work draws on the asset management, reliability and data standards below, with the industry bodies supplying practice. They are reference points for choosing an approach rather than a prescription.
| Reference | What it covers | Where it helps on fixed plant |
|---|---|---|
| ISO 55001 | Requirements for an asset management system | The planning, objectives and review cycle the strategy sits inside |
| ISO 14224 | Equipment taxonomy and the collection of reliability and maintenance data | The hierarchy, failure codes and data that make history analysable |
| ISO 17359 | Condition monitoring and diagnostics of machines | Choosing techniques and alarm limits for the failure modes that give warning |
| SAE JA1011 and IEC 60812 | The criteria for an RCM process, and FMEA and FMECA method | Strategy development for the critical systems |
| AS 4324.1 | Design of the steel structures of bulk handling machines such as stackers and reclaimers | Inspection and structural integrity of the large machines |
| CEMA publications | Belt conveyor design and installation practice | Conveyor and transfer point inspection and maintenance practice |
| SMRP best practice metrics | Standard definitions for maintenance and reliability measures | Measuring the program so comparisons hold |
Common mistakes
- Running the plant on the mobile fleet's model, with hour-based intervals on equipment that wears by the tonne.
- Monitoring everything, acting on nothing. Condition data with no work process behind it.
- A shutdown cycle set by habit, so parts are either changed early or run past their life.
- Scope that grows on the day because wear parts were not measured before the freeze.
- Long lead wear parts ordered from the shutdown scope instead of from the wear rate.
- A hierarchy built from the vendor's equipment list, with no levels that match how the plant is actually operated and maintained.
- Failure codes nobody uses, so every failure is coded as other.
- Availability averaged across the plant, hiding the one circuit that limits the tonnes.
Building a fixed plant maintenance strategy
Rank criticality
Consequence of failure for each item, so the analysis effort follows the risk.
Analyse the critical systems
RCM or FMECA on the items whose failure stops the plant or hurts people.
Template the rest
Standard strategies by equipment class, tuned with site wear data.
Set the shutdown cycle
From the longest-lived shutdown-bound task, with the rest grouped underneath.
Load the CMMS
Hierarchy, maintenance plans, counters, condition limits and bills of materials.
Measure and correct
Wear life, failures and shutdown performance fed back into intervals and scopes.
Rank criticality
Consequence of failure for each item, so the analysis effort follows the risk.
Analyse the critical systems
RCM or FMECA on the items whose failure stops the plant or hurts people.
Template the rest
Standard strategies by equipment class, tuned with site wear data.
Set the shutdown cycle
From the longest-lived shutdown-bound task, with the rest grouped underneath.
Load the CMMS
Hierarchy, maintenance plans, counters, condition limits and bills of materials.
Measure and correct
Wear life, failures and shutdown performance fed back into intervals and scopes.
Common questions
What is fixed plant maintenance?
Fixed plant maintenance is the care of the stationary processing and handling equipment on a mine or industrial site: crushers, screens, mills, conveyors, feeders, pumps, cyclones, thickeners, filters, stackers and reclaimers. It differs from mobile equipment maintenance in duty, access and strategy, because the plant runs continuously, handles abrasive material and can usually only be opened up during a planned stop.
How is fixed plant maintenance different from mobile equipment maintenance?
Mobile fleet is maintained by the hour on a cycle set largely by the manufacturer, in a workshop, one machine at a time, while the rest of the fleet keeps working. Fixed plant runs as a single connected train, wears by the tonne rather than the hour, is maintained in place, and a stop on one item usually stops the lot. That is why fixed plant work is organised around shutdowns and redundancy, and mobile work around service intervals.
Which maintenance strategy should fixed plant use?
A mix, chosen by criticality and by how each failure mode behaves. Condition monitoring suits bearings, gearboxes and motors that give measurable warning. Fixed interval replacement suits liners, screen media and idlers whose wear follows tonnes. Failure finding suits protective devices. Run to failure is right for low consequence items where a repair costs less than prevention. Reliability centred maintenance or FMECA sets the strategy for the critical systems, and templates cover the rest.
How often should a processing plant have a shutdown?
It depends on the wear life of the parts that can only be changed when the plant is down, and on the process itself. Crushing and screening plants commonly run short, frequent stops for liners and screen media, while a concentrator plans around mill reline intervals measured in months. The right answer is the cycle that lets the longest-lived shutdown-bound task be done before it fails, with the shorter-lived work grouped underneath it.
What KPIs are used for fixed plant maintenance?
Availability and utilisation of the plant and its constrained circuit, planned maintenance compliance, schedule compliance and break-in work, backlog in weeks, mean time between failures for repeating failure modes, shutdown duration against plan and scope growth, and maintenance cost per tonne. The SMRP best practice metrics give standard definitions so sites can compare like with like.
What systems does fixed plant maintenance run on?
A CMMS or EAM holding the asset hierarchy, maintenance plans, work orders and history, a condition monitoring program feeding alarms into that system, a data historian supplying process and runtime data, and a planning and scheduling process that joins them. The hierarchy and failure codes are the foundation: without them the history cannot be analysed and the strategy cannot improve.
What does a fixed plant maintenance strategy document contain?
For each asset or asset class: its criticality, the failure modes that matter, the task chosen for each (condition, interval, failure finding or run to failure), the interval and its basis, the condition limits that trigger work, the spares and wear parts it depends on, and whether the task is online or shutdown bound. It is held in the CMMS as maintenance plans, with the analysis behind it kept where it can be revisited.
Key terms
Plain-language definitions from our glossary for the concepts this article leans on.
Standards and further reading
- ISO 55001:2024 Asset management system requirements (ISO)
- ISO 14224:2016 Collection and exchange of reliability and maintenance data for equipment (ISO)
- ISO 17359:2018 Condition monitoring and diagnostics of machines, general guidelines (ISO)
- IEC 60812:2018 Failure modes and effects analysis (FMEA and FMECA) (IEC)
- SAE JA1011 Evaluation criteria for reliability-centered maintenance (RCM) processes (SAE International)
- AS 4324.1:2025 Mobile equipment for continuous handling of bulk materials, general requirements for the design of steel structures (Standards Australia)
- Belt Conveyors for Bulk Materials, 7th edition (CEMA)
- SMRP best practices and metrics guidelines (SMRP)
- Guidelines library for mining technology and interoperability (Global Mining Guidelines Group)
Related case studies and tools
- Reliability engineering and asset strategy program (case study)
- Predictive maintenance and condition monitoring (case study)
- Shutdown coordination platform (case study)
- Mining solutions (solution)
- Schedule Compliance Calculator (tool)
- MTBF / MTTR Calculator (tool)
Related reading
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