Developments in the Processing of the "Hi-Tech" metals

The Minor Metals classification includes metals which have no obvious practical use, or those which do have a potential practical use but cannot be economically extracted.  A good example is nickel, which in the early 20th century was regarded as a minor metal, until it was discovered that nickel and chromium, when alloyed with mild steel (itself an alloy of iron and 0.2% carbon), could produce an alloy steel with good mechanical properties, but which would not corrode. These stainless steels, of which 18/8 (18% Cr, 8% Ni) is the most well known, rapidly changed nickel's status from minor metal to steel making metal, allowing it to be mined at high tonnages.

In the late 19th century aluminium was more precious than gold, and classified as a minor metal, although it was well known that it had potential as a light, strong metal which would not corrode, due to its passive oxide layer. No one of sound mind would have predicted that aluminium would one day be a cheap metal in global use for common household utensils, the invention of the Bayer and Hall-Héroult processes allowing the economic mass processing of bauxite ores.

When I was at University studying metallurgy in the 1960s, the rare earth elements were classed as minor metals- who had even heard of neodymium, now essential in the production of powerful rare earth permanent magnets, used in wind turbines and many other applications (see also posting of 11 February 2013)? 

Lithium was essentially a curiosity, the third element in the Periodic Table, and the lightest metal. Now, of course it is in high demand for light, powerful batteries, and the increasing prevalence of electric cars will increase the demand for this once minor metal.

The rare earths and lithium are primary mined, but some of the once minor metals, such as gallium, germanium and indium, which are essential for our modern way of life, are by-products of base metal mining.

The importance of all these 'Hi-Tech' metals cannot be overestimated and MEI is pleased to announce our first international conference on the mineral processing and extraction of the hi-tech metals (Hi-Tech Metals '18) in Cape Town in November of next year. The conference will immediately follow Process Mineralogy '18 at the Vineyard Hotel.

Towards a circular economy is the theme of another MEI Conference next year, Sustainable Minerals 18. How well do the hi-tech metals fit into the circular economy? Not very well at all unfortunately. Take indium, for instance, now critical to our modern lifestyle, the most important ingredient, as an indium-tin oxide,  in the production of ubiquitous touch screens. Indium is produced in small amounts from the mining of Zn ores, and the sheer number of smart phones, tablets etc. produced each year requires around 700 tonnes per year of indium. Recent estimates however, suggest that total reserves are around 16, 000 tones, so it is a very finite resource.

So is recycling the answer, the aim of the circular economy? Unfortunately not at present- a smart phone for instance contains around half of the elements of the Periodic Table, and indium contributes around 0.02 g, so recovery by recycling of indium, and all the other metals in the phone, many of which are locked together as alloys, is unfortunately not practical as the moment, yet another reason why research into mineral processing and extractive metallurgy is so critical to modern life.

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