Gold Recovery Rates: From Laboratory Results to Mine Economics
Gold in a deposit is not the same as gold recovered for sale. Between those two points sits a processing system with its own technical limits, operating requirements, and costs. For investors, a recovery assumption can materially change a project’s economics—even when the gold price and reported ore grade remain unchanged.
Evergreen investor education | September 13, 2026
Separate grade from recovery
Grade describes the concentration of gold in the material being assessed. Recovery describes the proportion captured through a specified processing route. A high-grade sample does not, by itself, establish the recovery achievable across a commercial operation. Always ask what material, process stages, and measurement period a quoted percentage covers.
Metallurgical testing examines how material responds to processing. ALS describes gold testwork ranging from initial amenability tests through process validation and variability studies. For an investment review, the practical question is whether the evidence supports the particular recovery assumption used in the financial model.
Ask what the samples represent
Request the sample-selection plan, not just the best result. Which parts of the deposit were tested? Do the samples cover the material expected during early production as well as later years? Ask a qualified metallurgist to explain whether important differences in ore type or condition remain untested.
A combined sample can be useful, but its average result may conceal weaker-performing material. Ask for the range of results and how management translates that range into the mine schedule. A single headline recovery should not replace an explanation of uncertainty.
Distinguish testing scale from operating proof
SGS describes scoping, bench, and pilot-scale testing for developing mineral-processing flowsheets—the sequence of processing steps. These are different forms of evidence, not interchangeable labels for a fully demonstrated commercial plant.
Ask whether the quoted result came from a small laboratory test, a larger pilot program, or sustained plant operation. Request the conditions behind it, including preparation requirements and processing time. For an operating mine, compare actual performance across reporting periods with the original assumptions and ask management to explain deviations.
See how recovery changes the calculation
Hypothetical example: Suppose material entering a plant contains 10,000 ounces of gold. At an assumed overall recovery of 90%, the plant captures 9,000 ounces. At 80%, it captures 8,000 ounces. That ten-percentage-point reduction means approximately 11.1% fewer recovered ounces—not simply 10% fewer.
At a purely illustrative selling price of $3,000 per ounce, the difference represents $3 million of gross metal value before selling adjustments, costs, taxes, and financing. These invented numbers are not current market quotations, GBDS project figures, or a return forecast. Recovered metal also should not automatically be treated as metal sold and paid for in the same period.
Evaluate the cost of improving recovery
A higher recovery percentage is not automatically the best economic outcome. Ask what additional equipment, energy, consumables, maintenance, or processing time the proposed improvement requires. Have management show the incremental cash benefit after those requirements, including any effect on production capacity.
Request a downside case combining weaker recovery with higher costs or a slower startup. Identify how the project would fund the gap and whether investor payments depend on achieving the optimistic case.
Follow the evidence into the model
The most useful review connects representative samples, processing evidence, operating assumptions, and cash flow. Continue with Gold Resources vs. Reserves and How Gold Prices Affect Mining Profits to examine other links in that chain.
Educational information only, not individualized investment advice or an offer of securities. Mining investments involve risk, including total loss of capital. Consult qualified technical, financial, and legal advisers when evaluating a specific project.