Mining and minerals
Mining Shutdown Planning: Mill Reline and Processing
In a mining and mineral processing plant the biggest shutdown job is usually a grinding mill reline, so the plan is built around that job: remove the worn liners, install new ones, and finish all other work in parallel before ramp-up. The critical path runs through the reline, and the other jobs fit inside its float.
How MaintWiz helps: Mill relines and crusher stops depend on crews, parts and access. The MaintWiz shutdown module gives plant teams one plan for scope, schedule, permits, spares and execution, from the first work package to close-out. See the module · Get the data sheet
By Jai Balachandran · Published · Last reviewed
What MaintWiz adds:Scope, schedule and permits in one planSpares status with SAPReadiness gatesFindings to the planner
Fact block
What do public sources say about mining and mineral processing shutdowns?
Public sources give little shutdown-specific data for mining: US surface mines must have power off and machinery blocked before repairs, and no vendor-neutral benchmark for mill reline duration or interval was found. 1
| Item | What public sources say | Source |
|---|---|---|
| Usual term | Shutdown, plant shutdown or maintenance shutdown; for grinding mills, a reline or liner change. No standard definition found | Searched; see sources |
| Machinery repair (US surface metal and nonmetal mines) | Repairs or maintenance are done only after the power is off and the machinery is blocked against hazardous motion; equipment may be run for adjustment or testing only where that cannot be done otherwise, and then with effective protection from hazardous motion (30 CFR 56.14105) | 30 CFR 56.14105 |
| Electrical work (US surface mines) | Electrically powered equipment is deenergized before mechanical work is done on it; power switches are locked out or other measures taken, and warning notices are posted and signed by those who will do the work (30 CFR 56.12016) | 30 CFR 56.12016 |
| Power circuits (US surface mines) | Power circuits are deenergized before work, with switches locked out or other measures taken; locks, signs or devices are removed only by the person who installed them or by authorized personnel (30 CFR 56.12017) | 30 CFR 56.12017 |
| Schedule logic and float | The GAO guide describes the critical path as the longest continuous sequence of activities and float as the time an activity can slip without delaying the finish | GAO schedule guide |
| How long a mill reline takes | No public, vendor-neutral benchmark found. Duration figures that exist come from equipment suppliers or single sites and vary by mill size and method, so none is used here | Searched; see sources |
| Interval between relines | No public, vendor-neutral benchmark found; it depends on the ore, the mill and the liner design | Searched; see sources |
Read with care. 30 CFR 56.14105 covers US surface metal and nonmetal mines; other mine types and countries have their own rules. Check the regulator that applies to your site.
Mill reline
What does a mill reline shutdown look like on the schedule?
A mill reline shutdown puts the liner removal and installation on the critical path and fits the other plant jobs into their float, then commissions the circuit once all of them are done. 4
The float arithmetic is in critical path vs critical chain; terms are in the shutdown turnaround glossary. A free Excel version is available: Mining mill reline shutdown checklist (.xlsx). A free Excel version is available: Mill reline plan (.xlsx).
| ID | Work package | Crew | Days | On the path? |
|---|---|---|---|---|
| MN-101 | Stop feed, run out and isolate the grinding circuit | Operations | 2 | Critical |
| MN-102 | Remove worn mill liners | Reline crew | 5 | Critical |
| MN-103 | Install new mill liners | Reline crew | 8 | Critical |
| MN-104 to 110 | Parallel work: ball mill drive, cyclones, pumps, conveyors, motors, crusher | Mechanical, electrical, crusher crew | 5 to 7 each | 6 to 11 days of float |
| MN-111 | Commission the circuit and ramp up | Operations | 3 | Critical |
Software
Can software help with a mining shutdown?
Software can hold the reline and the parallel jobs in one schedule with float, track liner and part readiness, and keep isolations and permits with each work package.
About MaintWiz. MaintWiz is an industrial AI platform with IoT, SAP integration and predictive maintenance (PdM) capabilities. Its shutdown and turnaround module helps plants plan, schedule, execute and close out shutdown work.
Also: product data sheet.
What the shutdown module covers
As described on the MaintWiz shutdown maintenance product page.
- Shutdown calendar and critical-path scheduling, with work order sequencing and dependencies
- Asset prioritization, so the most critical equipment is scoped first
- Resource planning for people, spares, heavy equipment such as cranes, and outsourced vendors
- Electronic permits to work, risk management and contingency plans
- Real-time progress monitoring: schedule adherence, cost variance, quality metrics and risk factors
- Step-by-step checklists, pre-restart testing protocols and post-shutdown analysis
Proof
What MaintWiz customers report
Figures as published in MaintWiz case studies on maintwiz.com. They come from maintenance management projects, not shutdowns.
Roles
What does a shutdown planner do at a mine?
A shutdown planner at a mine turns the scope into work packages, links them into a schedule with float, books crews, liners and lifting gear, and reports progress against the baseline to the shutdown manager. 4
The role works with the maintenance superintendent, operations and the contractor who supplies the reline crew. For role definitions see shutdown team roles and RACI, and for the package format see shutdown work packages.
Checklist
What belongs on a mill reline checklist?
A mill reline checklist should cover isolation and blocking against motion, control of the barring arrangement, confined space entry, lifting, liner and tool readiness, the critical path and float, the crew plan and the restart plan.
A download is available with the free shutdown templates.
| Check | Basis |
|---|---|
| Mill drive, feed and water isolated, locked and tagged | 30 CFR 56.14105: power off and machinery blocked against motion |
| Barring or inching arrangement controlled during the work | 30 CFR 56.14105 |
| Confined space entry plan for the mill shell | Site procedure and applicable regulator |
| Lift plan and liner handler checked before use | Site procedure; heavy liners |
| Liner set and handling tools on site before the stop | Material readiness; see spare parts guide |
| Critical path and float known for the reline and parallel work | GAO guide terms |
| Crew and shift plan confirmed for the reline | Resource loading |
| Restart and ramp-up steps agreed with operations | Plant restart plan |
| Mill drive and feed equipment deenergized and locked out before mechanical work; warning notices signed | 30 CFR 56.12016 |
| Lockout devices removed only by the person who applied them or by authorized personnel | 30 CFR 56.12017 |
A working template pending review by a mining engineer. The general list is the 40-step shutdown checklist. This is not regulatory advice.
Visuals
Save the mining shutdown charts
Two charts for the maintenance planning meeting. Click either for the full-size image.
FAQ
Frequently asked questions
What is a mill reline?
The replacement of worn liners inside a grinding mill. It is usually the largest and longest single job in a mineral processing shutdown.
How long does a mill reline take?
There is no published benchmark. Duration varies with mill size, liner design and crew, so plan it from your own history.
How often should a mill be relined?
There is no published benchmark. It depends on the ore, the mill and the liner design.
Do electrical lockout rules apply?
For US surface mines, 30 CFR 56.12016 requires electrically powered equipment to be deenergized before mechanical work, and 56.12017 limits who can remove locks and signs from power circuits. 2,3
Do isolation rules apply?
For US surface metal and nonmetal mines, 30 CFR 56.14105 says repairs and maintenance are done after the power is off and machinery is blocked against hazardous motion. 1
What is on the critical path of a reline shutdown?
Usually the liner removal and installation, with the other jobs in their float. 4 See critical path and float.
Who plans a mining shutdown?
A shutdown planner working with the maintenance superintendent, operations and contractors; see the team roles guide.
Does this cover underground mines or other countries?
No. Check the regulator and standards that apply to your site.
Is the schedule on this page real?
No. It is an invented example to show how the critical path sits on a reline.
Sources
Sources
- eCFR, 30 CFR 56.14105, Procedures during repairs or maintenance (MSHA, surface metal and nonmetal mines; read via Cornell LII)
- eCFR, 30 CFR 56.12016, Work on electrically-powered equipment (MSHA, surface metal and nonmetal mines; read via Cornell LII)
- eCFR, 30 CFR 56.12017, Work on power circuits (MSHA, surface metal and nonmetal mines; read via Cornell LII)
- US Government Accountability Office, GAO Schedule Assessment Guide: Best Practices for Project Schedules (GAO-16-89G, December 2015)
Plan your next shutdown in one system
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