Cut-Off Grade
Derive a mass-fraction cut-off grade from caller cost, realized metal price and recovery; excludes capacity constraints, taxes and multi-metal credits.
Description
A simplified cut-off grade balances ore-treatment cost with recovered realized metal revenue.
A simplified cut-off grade balances ore-treatment cost with recovered realized metal revenue. Grade is expressed as a metal mass fraction of ore, so price must be per tonne of metal.1
The tool returns cutoffMassFraction, cutoffPercent. The computation uses supplied observations and parameters rather than acquiring measurements.
When to use Cut-Off Grade
Use this for the following task: Derive a mass-fraction cut-off grade from caller cost, realized metal price and recovery; excludes capacity constraints, taxes and multi-metal credits. Prepare observations and calibration parameters on the same unit and reporting basis.
How to use Cut-Off Grade and understand its results
- Prepare the measured quantities and supplied model parameters. Match the units and align paired lists before calculating.
- Enter oreCostPerTonne, metalPricePerTonne, realizationFraction, processRecovery according to the field table, then run the tool.
- Read cutoffMassFraction, cutoffPercent. Use the calculation below to interpret the selected mean or the model’s signs, units and comparison flags.
- Review the supplied assumptions and calibration before comparing or reporting the result.
| Input field | Meaning | Value type and bounds | Requirement |
|---|---|---|---|
| oreCostPerTonne | Ore cost per tonne | number | Required |
| metalPricePerTonne | Metal price per tonne | number | Required |
| realizationFraction | Realization fraction | number | Required |
| processRecovery | Process recovery | number | Required |
Use nonnegative ore cost, positive metal price and realization and recovery fractions in (0,1]. All monetary values share a currency.
cutoff fraction = oreCost/(metalPrice×realization×recovery); percent = 100×fraction The symbols and boundary conditions refer to the supplied fields and the implementation described above.
| Output field | Meaning | Value type |
|---|---|---|
| cutoffMassFraction | Cutoff mass fraction | number |
| cutoffPercent | Cutoff percent | number |
{
"input": {
"oreCostPerTonne": 20,
"metalPricePerTonne": 5000,
"realizationFraction": 0.8,
"processRecovery": 0.5
},
"output": {
"cutoffMassFraction": 0.01,
"cutoffPercent": 1
}
}Limitations and assumptions
The result can exceed one when the supplied economics require more than 100% grade. Capacity, taxes, multi-metal credits and optimal scheduling are outside the calculation.
Numerical inputs must be finite. Input-shape and calculation checks do not establish measurement quality or the validity of a supplied calibration.
Alternative or Complementary methods
Choose Lerchs-Grossmann Weight when you need its operation: Calculate economic node weights for process/waste blocks; prepares weights but does not execute Lerchs–Grossmann closure or precedence slopes. Choose Breakeven Stripping Ratio for the complementary operation: Estimate breakeven waste/ore mass ratio from recovered revenue and incremental costs; negative margins are retained, not converted into feasible stripping plans.
Background reference: Surface Mining Technology: stripping ratios and pit layouts.
References
-
Surface Mining Technology: stripping ratios and pit layouts — NPTEL, Indian Institute of Technology Kharagpur
Similar or alternative tools
- Lerchs-Grossmann Weight
Calculate economic node weights for process/waste blocks; prepares weights but does not execute Lerchs–Grossmann closure or precedence slopes.
- Breakeven Stripping Ratio
Estimate breakeven waste/ore mass ratio from recovered revenue and incremental costs; negative margins are retained, not converted into feasible stripping plans.