Friday 2 December 2011

Nine killed at illegal rare-earth mine in Guangxi Zhuang Autonomous Region, southern China.

On Saturday 26 November 2011, at about 3.30 in the afternoon, a major landslide occurred at a rare earth element mine in Cangwu County in the Guangxi Zhuang Autonomous Region in southern China. The mine has been described as illegal by local authorities, who have made a number of arrests connected with the incident. It was initially thought that seven workers had been killed, but nine bodies have now been recovered and rescuers are still searching the (extensive) site. Rescue attempts are being coordinated by the Mayor of Wuzhou City, Wang Kai.
Rescuers uncover a vehicle, inside which one of the victims was found.

Rare earth elements, or lanthanides, are elemental metals with atomic numbers ranging from 57 to 71, also referred to as 'f-block elements'. In addition the elements scandium and yttrium are commonly known as rare earth elements, because they are generally found in the same deposits as the lanthanides. These elements have proved to be extremely useful in modern electrical items such as mobile phones, causing their value to rise rapidly in recent years, which has lead to problems with illegal extraction in China and some other countries.

The Periodic Table showing the rare earth elements; the lanthanides plus scandium and yttrium.

Despite their name, the rare earth elements are not especially rare, they are found at trace levels in many rocks, and are far more abundant than traditional precious metals such as gold. However deposits containing significant amounts of rare earth elements are unusual, and the elements are difficult to extract. The commonest method of rare earth element extraction is to pump large quantities of strong acid into mineral bearing rocks, in the hope of dissolving the desired elements. This appears to have been the method used in Cangwu, on this occasion dissolving more than the miners had bargained for, and causing a significant collapse in rocks beneath the site.

China currently produces about 90% of the world's rare earth elements, with Chinese companies controlling much of the production outside of China. This has lead to complaints by some countries that China is establishing a monopoly in the elements. Despite this legitimate Chinese producers have struggled to keep up with the demands of the country's rapidly growing industry, leading to a ready market for rare earth elements produced by unlicensed, unregulated operations such as the one at Cangwu, which the Chinese authorities have struggled to control.

An additional problem with rare earth element production is that the ores that contain these elements often also contain the radioactive elements thorium and uranium, which will also come out of the rocks with acid leaching.. In one notable case a mine at Bukit Merah in Malaysia became so radioactive that the Malaysian authorities became convinced that the Japanese owners of the plant, Mitsubishi, were secretly using the site as a dump for radioactive waste produced elsewhere.