Rumours are circulating that reserves of indium could soon run out, threatening the production of displays, LEDs, and lasers. But if you take a hard look at the evidence, you’ll find that the naysayers are ill-informed and there is plenty indium to go round for many decades, argues Malcolm Harrower from Indium Corporation.

In today’s media, you’ll find plenty of stories about the gradual elimination of important natural resources and the consequences this will have on our lives when they run out. At the top of this list of resources is oil, a key fuel for transportation, heating, and the production of plastics. The concern from some quarters is that this ‘black gold’ will eventually run out, while others, who have thought about it more deeply, believe that this situation is more delicate, arguing that there are widespread, frightening consequences associated with a fall in global production.

Demand for oil is generally on the rise, and some experts predict that when it outstrips supply – a scenario that has been coined Peak Oil – the price will rocket, leading to a worldwide recession and hike in unemployment. This prediction, they say, is even backed by historical evidence. For example, following the Arab oil embargo of 1973 that cut-off global supply, the price of a barrel of oil quadrupled, leading to a doubling of US unemployment to 9 percent.

Another resource that is particularly important to our global community is indium. Indium is contained in the metal organic source trimethylindium, which is used to make blue and green LEDs. Additionally, indium is the key ingredient in indium-tin oxide (ITO), a transparent, conductive film that coats the glass used in the displays of TVs, netbooks, and smartphones. It is also a required element for IGZO transistors, which are incorporated in the latest displays that promise to take clarity to a new level by moving beyond 1080 lines. It is also featured in engine bearings and alkaline manganese batteries.

Can the arguments about Peak Oil be applied to indium? Well, not really, because there is a fundamental difference between the way that oil and indium are used. The vast majority of the oil that is produced is destroyed in a combustion process, while minerals, such as indium, can be utilised and re-utilised.

In fact, there are several sound arguments to suggest that the ‘doomsday’ oil resource scenario can be averted in indium. For starters, mines continually reinvigorate their resources through exploration and development, with technological improvements allowing extraction of reserves previously thought of as unobtainable. This means that tailings, which may be uneconomic to a particular company at one point in time, remain as reserves that can be extracted when it is economically feasible to do so. What’s more, current reserves only represent a small portion of what is available in the earth’s crust, and previously unknown deposits are being continually discovered. And there is also the large, increasingly popular option for recycling. Recycling involves more efficient use of materials in the production loop, and increasingly incorporates ‘urban mining,’ which is the recovery of resources that lie around us every day for re-use.

Recycling is a common practice in the largest single application for indium – the deposition of ITO to form a transparent electrode used in the screens of electronic devices. A vacuum process called sputtering coats this oxide to the glass, but a significant proportion of indium is left on the depleted sputtering target. This indium can be recovered using an incredibly quick process that enables an efficient use of the material in the production and process loop. This recycling ultimately contributes approximately 60 percent to the overall annual indium supply chain.

The magnitude of this supply has to be determined in order to assess the overall supply and demand for indium. In-depth calculations of this supply have been performed by our team at Indium Corporation, motivated by our desire to ensure accuracy in the discussion surrounding the level of metal reserves, and indium in particular.

Our experts began by assessing and calculating all the known deposits of zinc, the largest source of indium. Accurate figures exist in Europe and the Americas, but only estimates are used for China and the Commonwealth of Independent States (CIS), because these regions’ figures are not easily accessible nor reliable. Summing these contributions together gives us a total of 53,000 metric tonnes (MT) of indium reserves, 30,000 MT from the West and 23,000 MT from China and the CIS. These numbers are undoubtedly significant, but how do they compare with figures for extraction and actual and predicted consumption?

The amount of indium mined from western sources is 1,000 MT a year, which equates to about one-thirtieth of the current estimate of reserves in this region. Of these reserves, one-third is not extracted, a similar proportion is left in tailings, and only about one-third is actually refined into indium metal. This leads us to estimate that for this year, production of virgin indium will total 310 MT from the West, and another 230 MT from China and the CIS, leading to an annual total of 540 MT of new material.

In addition to this virgin material, there is indium that results from the recycling of spent ITO targets. Thanks to a fast recycling time and metal turnover of three-to-four times a year, nearly 900 MT of the total 1230 MT per annum of indium used in ITO production is recovered from the production process and recycled back into metal and targets.

Other applications consume another 300 MT per year, giving a total consumption of 1550 MT per annum. Although this figure is increasing at a steady rate, so is the amount of material recovered by recycling. Given the level of reserves, it is safe to say that there is plenty of indium to go round. In fact, based on current consumption, there is enough indium to last for 100 years. So those in the compound semiconductor industry should not worry about having enough indium to make their LEDs and lasers, or whether when they go home and find that their TV has stopped working, there will be enough of this metal to make the conductive coatings on their next display.

A short history of indium

German chemists Ferdinand Reich and Hieronymus Theodor Richter discovered indium in 1863, just in time for this element to feature in Mendeleev’s first periodic table, which came out in 1869. One of the primary reasons why it had not been discovered before then was that it had not been found in its own right as a pure, extractable metal. Instead, it was uncovered as a trace element in combination with other major metals. Indium is most commonly found in conjunction with zinc and tin deposits, and extracted along with these metals further down the refining chain after removal of the major elements.

Due to this, indium is included in the pantheon of ‘minor metals.’ These minor metals have been developed as a specialty market in themselves, with companies dedicated to servicing that market, including Indium Corporation, which was founded in 1934.