Stripping Ratio Calculator: Surface Mining Overburden-to-Ore Economics

How It Works

1. Enter Overburden Data

   Input the thickness of overburden (waste above the ore) and its in-place density. Include soil, weathered rock, and any non-economic material that must be removed.

2. Enter Ore Body Data

   Input the thickness of the ore body and its density. Include grade or quality if computing a value-based breakeven ratio.

3. Enter Cost Parameters

   Optionally input cost per unit volume for overburden removal and value per unit of ore recovered. This enables breakeven stripping ratio calculation.

4. Review Stripping Ratio

   See the volumetric ratio (waste per ore volume), weight-based ratio (tons per ton), and breakeven ratio. If actual exceeds breakeven, that portion of the deposit is uneconomic for surface mining.

Built For

• Mine planners evaluating economic viability of surface mining deposits at different commodity price scenarios
• Geologists estimating stripping ratios during exploration drilling to rank deposit targets by economic potential
• Mining engineers determining ultimate pit limits by comparing incremental stripping ratio against breakeven at each bench
• Financial analysts preparing mine feasibility studies with sensitivity analysis on stripping ratio and commodity price
• Environmental engineers estimating waste rock volumes for reclamation planning and bond calculation
• Coal mine operators evaluating contract mining bids based on cost per bank cubic yard of overburden
• Permit engineers calculating disturbed area and waste disposal volumes for mining permit applications

Features & Capabilities

Volumetric Stripping Ratio

Waste volume divided by ore volume. The standard metric for surface mining in yd3:yd3 or m3:m3.

Weight-Based Ratio

Converts volumes to tons using material densities. Reports in tons waste per ton ore. Useful when contracts or costs are weight-based.

Breakeven Ratio Calculator

Enter overburden removal cost and ore value to calculate the maximum stripping ratio at which mining is still profitable. The decision point for pit depth.

Price Sensitivity Analysis

Test multiple commodity prices to see how breakeven ratio changes. Identifies the price floor at which the deposit becomes uneconomic.

Swell Factor Adjustment

Converts in-place (bank) volumes to loose (hauled) volumes using a swell factor. Typical swell: rock 1.4-1.6, soil 1.2-1.3, sand 1.1-1.2.

PDF Export

Export stripping ratio analysis for mine feasibility reports, economic evaluations, or investor presentations.

Assumptions

• Waste and ore volumes are estimated from geological cross-sections or block model data.
• Material densities (bank and loose) are uniform within each material type.
• Overburden removal cost and ore mining cost are expressed as cost per unit volume or weight.
• Ore value is based on a single commodity price and assumed recovery rate.
• Pit slope angles are stable and do not require additional waste removal for buttressing.

Limitations

• Does not model pit optimization (Lerchs-Grossmann or floating cone) for optimal pit limits.
• Ignores haul distance, road grade, and truck cycle time variations with pit depth.
• Does not account for selective mining losses or dilution at the ore/waste contact.
• Commodity price volatility over the mine life is not modeled — uses a single price scenario.
• Does not include reclamation costs, royalties, or taxes in the breakeven calculation.

References

• SME Mining Engineering Handbook, 3rd Edition — surface mining economics.
• Hustrulid, Kuchta, and Martin, Open Pit Mine Planning and Design.
• CIM/SME guidelines for economic evaluation of mineral projects.
• Whittle Consulting — pit optimization and strategic mine planning references.

Frequently Asked Questions