Byproduct Mining
Also: Byproduct Recovery, Co-product Mining, Secondary Metal Recovery
Byproduct mining refers to the recovery of a precious metal as a secondary product during the extraction of another, primarily targeted raw material.
In byproduct mining, a precious metal is not recovered as the primary target but as a metallurgical by-product during the processing of another ore. The primary metal — often copper, lead, zinc or nickel — bears the main burden of extraction and processing costs; the precious metal is obtained virtually free of charge alongside it, significantly improving the overall economics of the mine.
Significance for precious metal markets
Silver in particular is highly dependent on byproduct mining: according to estimates by the Silver Institute, around 70–75 % of global silver mine production comes from mines whose primary target is copper, lead or zinc. A similar picture applies to palladium, a significant share of which is recovered as a byproduct from South African platinum mines and Russian nickel operations.
This structure has an important market consequence: the supply of byproduct metals barely responds to their own price. If the silver price rises sharply, a copper mine will not expand its production for that reason alone — the production decision is driven by the copper market. Conversely, the silver supply remains high even when the silver price falls, as long as copper remains profitable.
Cost accounting: byproduct credit
In the mining industry, revenues from byproducts are offset as a byproduct credit. This reduces the effective production costs (All-in Sustaining Costs, AISC) of the primary metal:
AISC (net) = Total costs − Byproduct credits
A copper producer that also recovers significant quantities of silver and gold can therefore report substantially lower net costs than a primary silver mine.
Typical byproduct combinations
| Primary metal | Common precious metal byproducts |
|---|---|
| Copper | Silver, gold, selenium, tellurium |
| Lead / Zinc | Silver, indium, germanium |
| Nickel | Palladium, platinum, cobalt |
| Platinum (PGM) | Palladium, rhodium, iridium, ruthenium |
Impact on supply and price
Since byproduct supply fluctuates pro-cyclically with the primary metal, boom phases in the base metals industry can lead to an oversupply of silver or palladium — irrespective of precious metal demand. On historical price charts, this effect can sometimes be seen as a price damper during periods of high industrial output.
Key takeaway
Byproduct mining accounts for a large share of global silver and palladium supply and largely decouples this supply from its own price — a structural factor that market observers should always bear in mind when conducting supply and demand analysis.