Lerchs-Grossmann Weight
Calculate economic node weights for process/waste blocks; prepares weights but does not execute Lerchs–Grossmann closure or precedence slopes.
Description
An economic block weight is a contribution to a pit-value model.
An economic block weight is a contribution to a pit-value model. Processed blocks earn recovered payable metal revenue and incur processing costs; waste blocks still incur mining cost.1
The tool returns blockEconomicWeights, sumEconomicWeight. The computation uses supplied observations and parameters rather than acquiring measurements.
When to use Lerchs-Grossmann Weight
Use this for the following task: Calculate economic node weights for process/waste blocks; prepares weights but does not execute Lerchs–Grossmann closure or precedence slopes. Prepare observations and calibration parameters on the same unit and reporting basis.
How to use Lerchs-Grossmann Weight and understand its results
- Prepare the measured quantities and supplied model parameters. Match the units and align paired lists before calculating.
- Enter blockTonnes, blockGradeFractions, processingFlags, metalPricePerTonne, recoveryFraction, payableFraction, miningCostPerTonne, processingCostPerTonne according to the field table, then run the tool.
- Read blockEconomicWeights, sumEconomicWeight. 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 |
|---|---|---|---|
| blockTonnes | Block tonnes | list of number | Required |
| blockGradeFractions | Block grade fractions | list of number | Required |
| processingFlags | Processing flags | list of number | Required |
| metalPricePerTonne | Metal price per tonne | number | Required |
| recoveryFraction | Recovery fraction | number | Required |
| payableFraction | Payable fraction | number | Required |
| miningCostPerTonne | Mining cost per tonne | number | Required |
| processingCostPerTonne | Processing cost per tonne | number | Required |
Use aligned nonnegative block tonnages, grade fractions and binary processing flags. Price is positive; recovery and payable fractions lie in [0,1], and costs are nonnegative.
weight[i] = tonnes[i]×(processFlag[i]×(grade[i]×price×recovery×payable−processingCost)−miningCost) The symbols and boundary conditions refer to the supplied fields and the implementation described above.
| Output field | Meaning | Value type |
|---|---|---|
| blockEconomicWeights | Block economic weights | list of number |
| sumEconomicWeight | Sum economic weight | number |
{
"input": {
"blockTonnes": [
100,
50
],
"blockGradeFractions": [
0.01,
0
],
"processingFlags": [
1,
0
],
"metalPricePerTonne": 5000,
"recoveryFraction": 0.8,
"payableFraction": 0.9,
"miningCostPerTonne": 5,
"processingCostPerTonne": 10
},
"output": {
"blockEconomicWeights": [
2100,
-250
],
"sumEconomicWeight": 1850
}
}Limitations and assumptions
This prepares economic weights but does not run the Lerchs–Grossmann maximum-closure algorithm, impose slope precedence or discount a mining schedule. All money values must share a currency and basis.
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 Floating Cone Value when you need its operation: Evaluate incremental value of a predefined floating cone excluding mined blocks; does not construct cone geometry or optimize pits. Choose Cut-Off Grade for the complementary operation: Derive a mass-fraction cut-off grade from caller cost, realized metal price and recovery; excludes capacity constraints, taxes and multi-metal credits.
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
- Floating Cone Value
Evaluate incremental value of a predefined floating cone excluding mined blocks; does not construct cone geometry or optimize pits.
- 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.