Based on the process described for zinc mining and processing, only 50%–70% of the
Of these indium-pregnant zinc concentrates, 30% are not sent to indium-capable smelters
The indium in the remaining indium-pregnant concentrates that sent to indium-capable
such as a sponge.
The impure indium is sent for advanced refining at various special metal refineries where
For every 100 units of indium metal mined along with zinc ores, only ~15–20 units is recovered as refined metal.
(Schwarz-Schampera and Herzig 2002; Mikolajczak 2009)
Heath Steele reports that 35.8% of indium in ore is reported to tailings and 51.4% went to zinc tailings (Schwarz-
Brunswick 6 and 12 mills reportedly recovered only 58.9% of the indium in zinc concentrate (Schwarz-Schampera
and Herzig 2002).
At Toyoha, the recovery of indium in zinc concentrates was ~96% (same as estimated for zinc recovery in zinc
concentrate). This mine was a main product indium producer, so these high recoveries are unlikely to be
representative of byproduct indium producers.
Indium recovery in mine concentrates is ~50%–70%.
As detailed above, the cumulative effect of these losses results in only 15%–20% of mined
estimates of mined indium and those for refined metal production. Given the low overall
recovery efficiency and cumulative losses of indium throughout the value chain, the figures for
total mined indium production presented in Table 3 (629 tonnes in 2013) could be significantly
The data on indium demand as well as primary refined indium provide useful benchmarks and
support an estimate of primary refined metal of 640–822 tonnes. Furthermore, various sources
tend to confirm an overall recovery efficiency of 15%–30%. With this in mind, and assuming
that the overall indium recovery efficiency corresponding with zinc ores is similar to those of
other main product ores, the total potential tonnes of indium mined in 2011 could be 2,130–5,870
tonnes, as tabulated in Table 8. The upper end of this range is almost an order of magnitude
greater than the estimate of 615 tonnes when using a methodology adopted by Roskill (2010).
Because the data on indium content in base metals ores are (according to Roskill’s own
estimates of overall recovery efficiency and levels of primary refined indium production, we
believe the mined indium estimate to more likely be ~5,200 tpa, coinciding with the midpoint of
the high scenario identified in Table 8. We use this figure in subsequent calculations.
Refined metal production (tpa)
Corresponding potential tonnes of contained indium mined per annum (tpa)
2,133 to 5,871 tpa
produced/overall recovery efficiencies.
The corresponding recovery efficiencies for low, mid, and high estimates of tonnes indium mined are 30%, 20%,
Sources: Own estimates; Mikolajczak (2009); USGS estimates (i.e., Tolcin 2011a and 2012a)
3.6 Summary of Primary Production
As noted in Table 8, total global production of primary refined indium metal in 2013 was 770
tonnes. In recent years primary indium production was ~640–822 tpa. China is the largest
producer of refined indium with ~50%–55% of global production. The remaining 45%–50% of
primary indium production is distributed among countries such as Belgium Canada, Japan, and
An analysis of overall indium recoveries has shown that significant losses of 70%–85% occur
throughout the value chain, representing a significant opportunity for increasing indium supply
in the short to medium term.
Until now, we have focused on summarizing existing supply characteristics of primary indium.
We now turn to estimating a supply curve for current indium production, which involves not
only estimates of indium quantities but the price at which indium can be produced. As is often
the case with mineral properties, the best and most detailed information available for costs and
efficiencies is contained in technical reports filed with the securities exchanges by midsized and
junior mining companies as part of their disclosure requirements.
Information in these reports
This methodology is incompatible with the methodology adopted by Roskill, because recovery of indium from ores efficiency
mined sources, which represents an unlikely scenario.
Often, large mining companies are not required to disclose detailed technical information about development projects or