Mine Planning & Scheduling

Planning turns designs into a timeline: life-of-mine, annual, monthly and weekly plans. Learn pushback sequencing, production scheduling to meet mill capacity and grade targets, stockpiling and blending, grade control and reconciliation, and schedule optimisation software.

A mine plan answers: which blocks, when, to where (mill, stockpile, dump), with which equipment? Good schedules deliver steady mill feed at the right grade, expose ore ahead of need, and bring high-value material forward to maximise NPV.

An analogy

Mine scheduling is like running a restaurant kitchen: the dining room (mill) must be fed continuously with the right mix of dishes (grades), so the cooks (fleet) prepare ahead and keep a pantry (stockpiles).

Planning horizons

Long-term (life-of-mine) plans set pushbacks and capital; medium-term plans set annual budgets; short-term plans direct daily digging, blasting and haulage. Each level must stay consistent with the one above.

Constraints

Mill capacity and feed grade limits, mining fleet capacity, maximum vertical advance (≈ 6–12 benches/yr per pushback), minimum mining widths, blending (e.g. impurity limits), dump and tailings capacity, and precedence between pushbacks.

Stockpiles and grade control

Stockpiles decouple mine and mill, store low-grade ore for later, and allow blending. Grade control uses blast-hole assays to mark ore/waste boundaries (dig lines). Reconciliation compares model, mine and mill tonnes and grade.

Schedule optimisation

Mixed-integer programming (Deswik, MineSched, Whittle, CPLEX/Gurobi) maximises NPV subject to constraints. Stochastic scheduling and real-time optimisation using fleet data are the frontier.

Formulas

• Blend grade: g_b = Σ f_i g_i
• Two-source blend: f_A = (g_target − g_B) / (g_A − g_B)
• Planning horizons: LOM → 5-yr → annual → quarterly → monthly → weekly → shift

Worked example: Two-source blend

Given: Pushback A 1.2 %, pushback B 0.6 %; Target 0.9 %

Find: Blend ratio.

• f_A = (0.9 − 0.6)/(1.2 − 0.6) = 0.5

Answer: 50 % from each

Worked example: Capacity-limited blend

Given: A limited to 400 t/h, B supplies 600 t/h; Mill 1000 t/h

Find: Mill grade and copper feed.

• g = (400 × 1.2 + 600 × 0.6)/1000 = 0.84 %
• Cu feed = 1000 × 0.0084 = 8.4 t/h

Answer: 0.84 % — below target; plan more A exposure or stockpile high grade

Common mistakes

• Wrong: Planning long-term without short-term realism. — Right: Check equipment, access and vertical advance limits.
• Wrong: Stockpiling everything 'for later'. — Right: Stockpiles degrade and cost rehandle — justify with NPV.

Applications

• Budgeting: Annual plans set production and cost targets.
• Blending: Iron-ore and coal quality control for customers.
• Reconciliation: Improving models from mill performance.

Key takeaways

• Plans cascade from LOM to shift.
• Constraints: mill, fleet, vertical advance, blends.
• f_A = (g_t − g_B)/(g_A − g_B).
• Optimise NPV with MILP tools.

Going further

• Stochastic scheduling: Plans robust to grade uncertainty.
• Short-interval control: Shift-level re-planning from fleet data.
• Geometallurgical scheduling: Schedules throughput and recovery, not just grade.