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Through the Gateway: A Look at Cadmium

Most of us have heard of Cadmium as a component of NiCd (Nickel-Cadmium) batteries.  To date, this also happens to be the most frequent use for the metal, accounting for about 85% of the Cadmium consumed globally in 2015.

A silvery metal with a bluish surface tinge, Cadmium is corrosion-resistant and its oxides are insoluble in water.  Nearly all the world’s Cadmium is derived as a co-product from Zinc sulfide ore, which is mined in many countries.  In the U.S., according to USGS, two companies produced refined Cadmium in 2015 – one by way of co-product recovery, and the other one by way of recycling of secondary cadmium metal from spent NiCd batteries and other scrap.

Over the past few years, there have been a slew of European Union directives classifying Cadmium as a toxic “hazardous substance” and prohibiting its use in many consumer products, including NiCD batteries in most power tools and Cadmium-containing quantum dots for light-emitting diodes for displays.  However, usage of industrial-sized NiCd batteries in electricity storage from photovoltaic systems could counter some of the decline in Cadmium usage.

The current solar power boom could do the same – and once again underscores our Gateway Metal/Co-product Metal focus:  Lab results for Cadmium-Telluride solar cells scored CdTe technology breaking efficiency records when it comes to converting energy in sunlight into electricity.  Just like Cadmium, Tellurium is also a co-product metal (though unlike Cadmium, it is not a Zinc co-product, but rather derived mostly in the Copper refinement process).  As such, both Cadmium and Tellurium are not mined in their own rights — but they are essential to a key 21st Century technology.

In light of materials sciences’ rapid pace of discoveries of new applications for metals and minerals, other new applications for Cadmium may also be found.

While exact data are withheld, the U.S. is currently considered a net exporter of Cadmium. However, what is instructive here is the fact that the metal is almost exclusively derived as a co-product – so whatever happens to the Gateway Metal Zinc will in some shape or form affect the supply scenario for Cadmium. Or, in other words, the road to Cadmium leads Through the Gateway.