Primary indium production is largely the result of byproduct production from sphalerite (zinc)
ores. As such, it is not significant to most indium-producing mining companies, and the value
chain from mining to refined metal often involves several companies with few companies
spanning the entire value chain. Furthermore, with total global primary production valued at
indium recovery is likely not of key economic importance for
costs to recover indium are not publically available and, because costs are intermingled between
main product, coproduct, and byproduct metals, miners and smelters probably do not explicitly
track the costs of indium internally.
As is often the case with mineral properties, technical reports filed by midsized and junior
mining companies with the securities exchanges as part of their disclosure requirements contain
the best and most detailed information available.
This information can then be used together
representative view of costs and production levels for various deposits. We adopt this approach
when examining what a supply curve for indium might currently look like and how this might
change going forward. We use a Monte Carlo simulation to generate short- and medium-term
supplies. As will subsequently be discussed in greater detail, we use data from the following
sources to build the supply curves:
A recent preliminary economic assessment of the Mount Pleasant indium-zinc-tin deposit
A catalogue of known indium-bearing deposits (Schwarz-Schampera and Herzig 2002)
Historical (long run) commodity prices for tin and zinc
Growth of main product zinc production and therefore extrapolated byproduct indium
Estimates of medium-term potential recovery efficiencies at new facilities (Thibault
The steps taken to generate the results differ slightly between generating the short- and medium-
term supply curves. In the short term, the indium need only cover its share of direct operating
costs; in the medium to long term, the indium needs to cover operating and capital costs and
generate a fair return to capital. We now look at each of these approaches in detail.
The Short Term
Focusing first on the short run, the operating cost estimate for the Mount Pleasant deposit is
examined in detail (Thibault et al. 2010). The preliminary assessment for Mount Pleasant
Assuming 822 tpa of indium metal × 1000 kg/tonne × $600/kg indium metal.
Large mining companies are often not required to disclose detailed technical information about development projects or
ongoing operations, because the performance of a single operation is not essential to the overall value of the company.
contains three production cases labeled “A,” “B,” and “C,” all of which assume that same mine
and plant head feed capacity but vary the degree to which the zinc, tin, and indium are refined.
In case “A” the design accommodates the recovery of a tin concentrate as well as a combined
indium and zinc concentrate. These concentrates are then shipped to third-party smelters for
further processing. Case “B” includes the concentrator plant from case “A” to recover a tin
concentrate that is shipped to third-party smelters; however, the treatment plant is expanded and
includes a hydrometallurgical plant for production of indium sponge of 95% purity and zinc
metal. Indium sponge is then pressed into briquettes and shipped to a third-party refinery for
upgrading to 4N8 purity. The zinc metal is sold directly to the market. Case “C” includes the
concentrator/hydrometallurgical plant of Case “B” indium sponge and zinc metal in addition to a
pyrometallurgical plant for production of tin chloride instead of tin concentrate. Various design
parameters for the three cases and their respective final products are summarized in Table 26.
Table 26. Mount Pleasant Production and Product Revenue
Summary for Production Cases “A” Through “C”
Annual production rate DMT
0.49% Indium 99.50%
Revenue relative to
850 tpd design capacity, 90% availability, 279,226 tpa
Applicable to case B
DMT = dry metric tonnes; "conc." = concentrate.
C$ refers to Canadian dollars. The conversion used by Thibault et al. (2010) at the time of drafting their report was C$1.10/US$.
Market price adjustment factor accounts for loss of indium in refining process to 4N8 grade and a price discount for indium sponge relative to the
Indium sponge treatment charges are per tonne of 4N* indium metal recovered after refining losses.
To assess the cost of producing indium, we concern ourselves with cases “A” and “B” only,
Mount Pleasant property, 40.5 tpa of indium may be produced as a coproduct along with zinc