🎓 Lesson 6
D4
Building Accurate Landed Cost Models
Landed cost is the total price of a material or component once it arrives at your mine site — including purchase price, shipping, taxes, customs, insurance, and handling.
🎯 Learning Objectives
- ✓ Calculate landed cost per unit for explosive cartridges shipped internationally using duty, freight, and local handling inputs
- ✓ Design a modular landed cost template that dynamically updates with exchange rate and fuel surcharge fluctuations
- ✓ Analyze cost variance between quoted supplier price and actual landed cost to identify hidden cost drivers
- ✓ Explain how landed cost errors propagate into blast design economics and unit cost per tonne of broken rock
- ✓ Apply Incoterms® 2020 rules to assign responsibility and cost allocation across supply chain handoffs
📖 Why This Matters
In open-pit blasting, a $500/tonne quoted price for ANFO may become $780/tonne after ocean freight, port demurrage, GST, road transport from port to blast site, and storage conditioning — eroding margin by 56%. Without accurate landed cost models, engineers unknowingly overdesign blasts (using excess explosives), misprice contracts, and misallocate CAPEX. This lesson bridges procurement finance and blasting execution — turning cost data into actionable engineering intelligence.
📘 Core Principles
Landed cost modeling rests on three pillars: (1) Cost attribution — assigning every expense to a specific BOM line item (e.g., emulsion vs. detonators); (2) Temporal alignment — matching costs to the period of physical receipt and usage (not invoice date), critical for IFRS 15 and mine accounting cycles; and (3) Traceability architecture — embedding audit trails from PO to blast log via ERP-integrated BOMs. Industry best practice requires modeling at the 'per-kilogram-at-bench' level, not per-container or per-order, because blast design sensitivity demands sub-1% cost precision. Failure to model landed cost separately from purchase price leads to systematic underestimation of consumable costs — especially for imported electronic detonators, specialty primers, and regulated explosives requiring hazardous goods certification.
📐 Total Landed Cost per Unit
This formula aggregates all cost elements incurred before material is ready for use in blast design or loading. It must be applied per unit (kg, cartridge, or kg-equivalent) to support fragmentation economics and powder factor validation.
Total Landed Cost per Unit
LCₚᵤ = [ (FOB × ER) + Freightₐᵤ + Insuranceₐᵤ + Dutyₐᵤ + GSTₐᵤ + LocalTransportₐᵤ + Handlingₐᵤ ] / TotalUnitsCalculates the full cost per unit delivered and ready for use at the blast site.
Variables:
| Symbol | Name | Unit | Description |
|---|---|---|---|
| LCₚᵤ | Landed cost per unit | AUD/kg | Final cost per kilogram available for loading |
| FOB | Free On Board price | USD/tonne | Supplier price at origin port, excluding freight/insurance |
| ER | Exchange rate | AUD/USD | Currency conversion factor at time of payment |
| Freightₐᵤ | Freight cost | AUD/tonne | Ocean/air freight, including bunker adjustment factor (BAF) |
| Insuranceₐᵤ | Cargo insurance | AUD/tonne | Typically 0.3–0.5% of FOB + Freight value |
| Dutyₐᵤ | Import duty | AUD/tonne | Ad valorem tax based on CIF value and HS code |
| GSTₐᵤ | Goods and Services Tax | AUD/tonne | 10% tax on landed value pre-GST in Australia; varies by jurisdiction |
| LocalTransportₐᵤ | Last-mile transport | AUD/tonne | Road haulage from port/depot to blast site, including hazardous load permits |
| Handlingₐᵤ | Site readiness handling | AUD/tonne | Unloading, inspection, conditioning, and ERP stock posting labor/materials |
Typical Ranges:
Imported electronic detonators (remote mine): AUD 18.50 – AUD 24.20/unit
Domestic ANFO (truck-delivered): AUD 0.85 – AUD 1.15/kg
Offshore emulsion (containerized, WA mine): AUD 2.20 – AUD 2.85/kg
💡 Worked Example
Problem: A mine in Western Australia imports 10,000 kg of water-gel emulsion from Chile. Quoted FOB price: USD 1,200/tonne. Freight: USD 180/tonne. Insurance: 0.5% of FOB value. Import duty: 5% of CIF value. GST (10%): applied to landed value pre-GST. Exchange rate: USD 1 = AUD 1.52. Local trucking (port to site): AUD 42/tonne. Handling & conditioning (humidity control, temperature stabilization): AUD 18/tonne.
1.
Step 1: Convert FOB to AUD: USD 1,200/tonne × 1.52 = AUD 1,824/tonne
2.
Step 2: Add freight & insurance: Freight = USD 180 × 1.52 = AUD 273.60; Insurance = 0.5% × (1,824 + 273.60) = AUD 10.49 → CIF = AUD 2,108.09/tonne
3.
Step 3: Add duty (5% of CIF): AUD 105.40 → Pre-GST landed value = AUD 2,213.49/tonne
4.
Step 4: Add GST (10%): AUD 221.35 → Post-GST landed value = AUD 2,434.84/tonne
5.
Step 5: Add local costs: AUD 42 + AUD 18 = AUD 60 → Final landed cost = AUD 2,494.84/tonne = AUD 2.4948/kg
Answer:
The landed cost is AUD 2.495/kg, which falls within the typical range of AUD 2.20–2.85/kg for imported emulsion in remote Australian mines.
🏗️ Real-World Application
At Newmont’s Boddington Mine (WA), a 2022 internal audit revealed a 19% underestimation of landed cost for non-electric down-the-hole (DTH) hammers sourced from Sweden. The procurement team used EXW (Ex Works) quotes but omitted 72-hour port demurrage fees triggered by delayed customs clearance for ATEX-certified tools. When integrated into the BOM for drill-and-blast cycle costing, this error inflated drill bit consumption assumptions by 14%, leading to premature reordering and $2.3M in excess inventory. After implementing a landed cost dashboard linked to SAP MM and Customs Broker APIs, landed cost variance dropped to <1.2% — enabling precise powder factor calibration and reducing explosive overuse by 6.3% per blast round.
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