Contained is not the same as recovered.

Start with the feed and its units

Ore grade describes the concentration of the metal in the material being measured. In this hypothetical example, one metric tonne of dry ore has an average silver grade of 300 grams per tonne. Multiplying 1 tonne by 300 g/t gives 300 grams of contained silver. The tonne is the mass of ore, not the mass of silver. A grade quoted for a selected specimen is not automatically representative of an entire processing feed.

Apply recovery to the contained metal

Assume that 80% of the silver entering the chosen process reaches its defined recovered product. The calculation is 300 g × 0.80 = 240 g recovered. The other 60 g does not reach that product within this simplified boundary. This does not mean that 80% of the ore mass becomes silver. Recovery tracks the selected valuable material, so its numerator and denominator must refer to the same metal and a clearly specified process.

Recovery and purity answer different questions

A plant can recover much of the feed’s silver into a concentrate that still contains other minerals. Its recovery percentage is therefore not the purity of a finished bar. Concentrate grade describes the composition of the product; recovery describes how much of the feed’s silver reached it. Mineral separation can involve trade-offs between these measures. A stronger result on one axis does not automatically improve every other part of the operation.

The arithmetic is not a feasibility study

The example fixes grade and recovery to make the relationship clear. Real planning must consider variations in ore, sampling confidence, processing behaviour, costs and the terms under which products can be sold. Higher contained metal does not guarantee a profitable operation. When comparing two projects, keep the reporting boundaries consistent: tonnes of ore, grams of contained silver and grams of recovered silver are useful quantities, but they are not interchangeable economic conclusions.

FOLLOW THE EVIDENCE

Sources & further reading

Sources checked 14 November 2026. Reference organisations do not endorse this website. Price examples are hypothetical and educational.