Mill Recovery Calculator
Calculate metal recovery percentage from head grade, tailing grade, and throughput for processing plant evaluation.
About this calculator
Mill recovery measures what share of the metal entering a processing plant actually ends up in the saleable concentrate rather than being lost to the tailings (waste). This calculator uses the simplified assay-based recovery estimate, Recovery = (Head Grade - Tailing Grade) / Head Grade x 100, which compares the metal grade of the ore feeding the mill against the metal grade still left in the waste stream -- the closer the tailing grade is to zero, the higher the fraction of metal that was successfully captured. This is an approximation commonly used when only feed and tailing assays are available: it assumes the concentrate's own tonnage is small relative to the feed tonnage, which holds reasonably well for high-grade concentrates (high concentration ratios) typical of gold and base-metal flotation circuits, but is a rougher estimate when the concentration ratio is low.
From recovery, the calculator derives daily and annual metal production (throughput times head grade times recovery fraction) and the resulting revenue at the entered metal price -- these feed directly into cash-flow projections for evaluating whether a processing plant's economics work at a given ore grade and metal price. Enrichment ratio (concentrate grade divided by head grade) is reported separately as a measure of how much the ore is being upgraded through processing.
Inputs
Results
Recovery
94%
How to Use This Calculator
- Enter Head Grade (g/t or ppm) — the metal grade fed into the mill.
- Set Tailing Grade and Concentrate Grade from metallurgical testing.
- Enter mill throughput (t/day) and current metal price ($/oz).
- Review Recovery (%) — the percentage of metal successfully extracted from the ore.
- Use Metal Produced/Day and Metal Produced/Year for cash flow and revenue projections.
How the result changes with Head Grade
| Head Grade | Recovery |
|---|---|
| 2.5 | 88% |
| 3.75 | 92% |
| 7.5 | 96% |
| 13 | 97.69% |
What each input means
- Head Grade
- Metal grade of feed ore entering the mill
- Tailing Grade
- Metal grade in the tailings (waste)
- Concentrate Grade
- Metal grade in the concentrate product
- Mill Throughput
- Daily mill feed tonnage
- Metal Price
- Metal price per troy ounce
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersHead Grade = 5, Tailing Grade = 0.3, Concentrate Grade = 200, Mill Throughput = 5000 = 5 input(s) provided
- Calculate RecoveryRecovery94 = 94
- Calculate Concentration RatioConcentration Ratio40 = 40
- Calculate Metal Produced/DayMetal Produced/Day755.5 = 755.5
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why does lowering the tailing grade increase calculated recovery?
Recovery = (Head Grade - Tailing Grade) / Head Grade x 100 -- a lower tailing grade means less metal is being lost to waste, which directly narrows the gap between head grade and tailing grade in the numerator, raising the calculated recovery percentage. A tailing grade approaching zero would approach 100% recovery.
Why does metal price not affect the recovery percentage?
Recovery is purely a metallurgical measure of how efficiently metal is being extracted from ore -- it depends only on head grade and tailing grade. Metal price only enters the calculation afterward, when converting the recovered ounces per day into a dollar revenue figure; it has no bearing on how much metal is physically captured by the mill.
How does mill throughput affect daily metal production?
Metal produced per day scales directly with throughput (tons of ore processed per day) at a fixed head grade and recovery rate -- processing more tons per day, without changing ore quality or plant efficiency, produces proportionally more recovered metal and proportionally more daily revenue.
What's the difference between recovery and enrichment ratio?
Recovery measures what FRACTION of the metal in the feed ends up in the concentrate (a measure of processing efficiency). Enrichment ratio measures how much the ore's grade has been UPGRADED by processing (concentrate grade divided by head grade) -- a plant can have high recovery with a modest enrichment ratio, or vice versa, since the two describe different aspects of the separation process.
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