Ultimate Pit Stripping Ratio

Compare cumulative/incremental stripping across nested shells; limits do not solve ultimate-pit optimization or establish slope feasibility.

Description

Nested pit shells have cumulative and incremental stripping ratios.

Nested pit shells have cumulative and incremental stripping ratios. Incremental ratios describe the extra waste needed for the extra ore between successive shells.

The tool returns cumulativeRatios (cumulative ratios); incrementalRatios (incremental ratios); acceptableIncrementalShellFlags (acceptable incremental shell flags). Input measurements and model parameters are supplied by the caller; the tool computes the stated summary rather than acquiring those measurements.

When to use Ultimate Pit Stripping Ratio

Use Ultimate Pit Stripping Ratio when you already have nestedPitOreTonnes, nestedPitWasteTonnes, maximumIncrementalWasteOreRatio and want cumulativeRatios, incrementalRatios, acceptableIncrementalShellFlags. This is useful for checking a supplied calculation, documenting a measurement convention, or comparing observations prepared on the same basis.

How to use Ultimate Pit Stripping Ratio and understand its results

Enter nestedPitOreTonnes, nestedPitWasteTonnes, maximumIncrementalWasteOreRatio using the field table below. Match the units, ordering and data boundaries described in the calculation.
Run the tool after checking the stated bounds and matching paired observations or categories. A malformed request gives a tool error rather than a usable measurement.
Read cumulativeRatios, incrementalRatios, acceptableIncrementalShellFlags. Use the calculation and interpretation below to distinguish amounts, ratios, signs and decision flags where applicable.
Review the supplied parameters and assumptions before using the result in a report or comparing it with another observation.

Input field	Meaning	Value type and bounds	Requirement
nestedPitOreTonnes	Nested pit ore tonnes	list of number	Required
nestedPitWasteTonnes	Nested pit waste tonnes	list of number	Required
maximumIncrementalWasteOreRatio	Maximum incremental waste ore ratio	number	Required

Use increasing positive cumulative ore and nondecreasing nonnegative cumulative waste. The first increment starts from zero; flag each incremental ratio at or below the supplied maximum.

cumulative = waste/ore; incremental = Δwaste/Δore

The symbols refer to the supplied quantities or generated values described above; unit conversions and comparison boundaries follow the stated implementation.

json

{
  "input": {
    "nestedPitOreTonnes": [
      100,
      200,
      300
    ],
    "nestedPitWasteTonnes": [
      100,
      250,
      600
    ],
    "maximumIncrementalWasteOreRatio": 2
  },
  "output": {
    "cumulativeRatios": [
      1,
      1.25,
      2
    ],
    "incrementalRatios": [
      1,
      1.5,
      3.5
    ],
    "acceptableIncrementalShellFlags": [
      1,
      1,
      0
    ]
  }
}

Limitations and assumptions

Acceptable shells are flagged individually; no optimal pit, precedence-constrained sequence or discounted cash flow is selected.

Numerical inputs must be finite. The tool checks its declared input shape and calculation constraints; those checks do not verify the quality, calibration or representativeness of the supplied observations.

Alternative or Complementary methods

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. Stripping Ratio: Aggregate bank-volume stripping quantities and distinguish waste/ore volume and mass ratios using supplied densities; excludes loose-volume swell.

Methodological background: Surface Mining Technology: stripping ratios and pit layouts.^[1]

References

Surface Mining Technology: stripping ratios and pit layouts — NPTEL, Indian Institute of Technology Kharagpur

Similar or alternative tools

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.
Stripping Ratio
Aggregate bank-volume stripping quantities and distinguish waste/ore volume and mass ratios using supplied densities; excludes loose-volume swell.