At present, new scrap used in the secondary production of indium is mainly sourced from spent
ITO sputtering targets. Sputtering is the process used in electronics manufacturing to apply ITO
to transparent and conductive electrodes for use in LCD or flat-panel display applications. Moss
et al. (2011) state that flat-panel displays and other ITO applications represent ~84% of total
indium demand. Due to inefficiencies in the current manufacturing process, only ~30% of the
indium is successfully deposited on the ITO thin-films when using planar sputtering targets.
More expensive rotary targets can yield higher efficiencies (Gibson and Hayes 2011). Up to70%
of remaining indium is, therefore, conceivably available for recovery and reuse.
According to the USGS, before about 1996
very little of the indium in ITO manufacturing
have installed significant recycling capacities. Unfortunately, because of metallurgical
complexities, not all the indium in new scrap can be recycled and reused in the manufacturing
process as losses. Overall, recovery is high and various estimates have placed the efficiency of
the ITO recycling process at 60%–70% (Phipps et al. 2007; Mikolajczak 2009). The turnaround
time for the recycling process is also an important consideration for recyclers, owing to
potentially significant inventory carrying costs and maximization of plant throughput capacity.
Market pressures and improvements in technology have enabled recyclers to decrease the recycle
claim time to about 15 days. These improvements reduce the overall demand for primary indium.
Given this level of recycling efficiency, if we assume that new scrap is sent to a recycling plant
and that the same indium continues to be used in a closed loop between the manufacturer and the
recycler, the overall effective deposition of indium in ITO applications increases from 30% (in a
single pass) to ~55%
successfully deposited. With a closed-loop recycling process, manufacturers can increase the
effective indium deposition from 30 units to 55 units. Therefore, of the total 55 units of indium
used, 30 were sourced from primary supply and 25 were sourced from the new scrap. Had
recycling not taken place, the manufacturer would have had to source an additional 25 units of
primary indium, but recycling reduced the primary indium demand. For example, without
recycling, manufacturers would have required an additional 83 units
of primary indium to
recycling system enabled the 25 units to be produced and reduced potential demand for primary
indium by 83 units.
In 1996, indium prices rose to ~$175 to ~$550/kg, indicating that at that point, indium could be recycled at a lower cost than
capacity, indicating that the recycling of indium remained profitable at prices of ~$175/kg.
If 100 units of indium metal enter the manufacturing process, approximately 30 units (or 30%) are deposited on thin-films in
be recovered through recycling. If the process repeats itself enough times and one assumes a closed-loop manufacturing and
recycling process, the overall indium lost is ~45% while ~55% of the initial 100 units of indium is successfully deposited.
Calculated as: 30/100 = 25 /s. Solving for ‘s’ yields 83.333.
Units available for ITO
Units lost to waste
% of indium wasted
The deposition success rate is assumed to be 30%; therefore, 70% of indium is available for recycling. We assume that if indium
manufacturing stage, only at the recycling stage.
Indium recycling efficiency is estimated to be 65% per recycling cycle.
Primary indium. All other figures relate to indium that is either entering recycling or has been recycled.
If 100 units of primary indium are used in ITO applications with recycling, the ITO applications will appear to have consumed
demand reported by manufacturers.
Of the original 100 units of primary indium entering the manufacturing process, 55 units (55%) are effectively deposited when
Of every 100 units of primary indium used in ITO applications, 128 units are a quantity that might appear to be entering the
Of every 100 units of primary indium used in ITO applications, 70 units enter the recycling plant. Because the 70 units enter
representative of recycling plant throughput as measured by producers.
Of the 100 units of primary indium entering the manufacturing process, 45 units (45%) are forever lost. This is due to a
Units of indium discarded in the waste stream may be recoverable at some later stage. We do not, however, have information
Source: Own calculations; Mikolajczak (2009)
The calculations in Table 9 also highlight the significant potential for inflated estimates of
reporting total consumption of indium in ITO applications by quoting the amount of indium
purchased, they may indicate that they used 183 units of indium over the period. However, as we
have shown, only 100 units entered the process, of which only 55 units were successfully
deposited. Similarly, new scrap recyclers may report that they produced 83 units of indium over
the period, because these would have been shipped from their facilities. Together with the 100
units reported by the primary producer, reported figures by all producers might lead one to
believe, incorrectly, that total supply over the period was 183 units. Again, total supply was only
100 units, of which 55 were deposited (30 from primary sources) and 45 were lost.