While China remains, for now, the world’s leading magnesium producer, alternative green technology-driven projects elsewhere are attracting attention as the industry in general looks to reduce its carbon footprint, and even China starts to close inefficient capacities, according to Roskill Information Services.
Magnesium is a light metal with a density of 1783 kg/m3—two-thirds that of aluminum and one-sixth that of steel. The strength-to-weight ratio of magnesium is 158 kNm/kg—higher than 130 kNm/kg for pure aluminum. Magnesium has a number of applications, including as a light alloy in in the automotive industry and an alloying element in aluminum alloys.
In the 1990s, the magnesium metal market was dominated by supply from North America (46%), what is now the CIS (25%) and western Europe (19%). Then came the rapid ascent of production in China and with it a flood of low-cost magnesium.
By the early 2000s production in France, Italy and Norway had ended. Producers in Canada had conceded defeat by 2008 and the US industry was reduced to just one player that would probably not still be around were it not for punitive anti-dumping duties imposed on imports of Chinese magnesium.
Today, well above 80% of the world’s magnesium comes from China. US output is for the domestic market and most CIS production is captive to titanium sponge. There would probably not be any production in Israel if the Dead Sea were not already being exploited for other commodities. A few new plants have been built outside China over the last decade but they have largely not been hugely successful.
A major distinction to be made is that non-Chinese plants typically rely on electrolytic processing in which liquid magnesium is produced from magnesium chloride. The source of magnesium can be from sea water, brine, dolomite, magnesite, and carnallite. Electrolytic processing is comparatively clean but usually expensive.
Most production in China uses thermal processing: the Pidgeon process. Based on silicothermic reduction of magnesium oxide, the Pidgeon process is cheap but has a high energy demand: 366 MJ/kgMg, compared to other common metals. The process suffers from excessive heat loss associated with the reduction process and ferrosilicon making.
The Pidgeon process is relatively easy, easy to adjust production to meet demand, and only requires a small amount of capital cost compared to electrolytic processes.
There is a substantial surplus of production capacity in China. Some older, smaller plants have already been closed. Others will likely follow and at the same time efforts are being made to reduce the carbon footprint of the industry in general.
While Roskill considers that further conventional plants are unlikely to be built in China, or anywhere else, new technologies are emerging.
Projects underway in Canada, Australia and the USA, several at advanced stages of development, are based on proprietary technology, three of them are based on waste materials (asbestos tailings or fly ash); all would have much lower GHG emissions than existing processes.
Although their combined capacity would amount to less than 10% of the current level of production, as the world looks towards a more sustainable future, it could be that these more environmentally friendly projects gain traction and become the start of a shift to green magnesium, Roskill suggests.
Wulandari, Winny; Brooks, Geoffrey; Rhamdhani, Muhammad; and Monaghan, Brian: “Magnesium: current and alternative production routes 2010.”