The truth about the Buyat Bay incident
Having read various articles and reports published recently in several mass media including The Jakarta Post about the Buyat Bay incident in which mining company PT Newmont was involved, I would like to present some facts pertaining to the matter.
No modern gold processing outfit uses mercury. It may have been used by old Dutch companies before World War II in the Dutch East Indies but technology and environmental awareness would prohibit companies to operate an amalgamation process with mercury. Instead, companies use the cyanidization process to extract the gold from the pulverized rock and the tailings (pulverized carbonaceous rock), after which the cyanide is detoxified in a process that breaks up the compound before it is discharged back into nature. In Newmont's case, the detoxified cyanide residue is piped to a depth of 80 meters below the ocean and rests on the bottom of a submarine ravine.
All gold mineralization in nature may have traces of Hg (mercury) sulfides along with traces of arsenic, silver, copper and other elements. They come in small amounts and when it is efficient they will be processed as by-products.
It is important to note these metals in nature, due to their small traces, if swallowed, will do no harm to humans for the reason that they remain stable.
It has been observed long before Newmont's operation (article from the Journal of Geochemical Exploration No. 50, 1994, page 493-500) by Laurence P. James on his paper issued on Sept. 16, 1993, that the use of the "Tromol-mill by small-scale miners became a possible environmental concern." He estimated that for the treatment of 100,000 tons or ore annually, in six runs per 24 hours, 300 days per year, at least five to 10 tons of mercury is lost and disposed into the open water system. This metallic mercury which is in itself highly toxic, is also converted by micro-organisms and plankton to the even more toxic organic methyl mercury. This has the potential to pollute the environment in gold districts all over Indonesia.
I would sincerely appeal to all concerned to abandon the free trade of mercury, which is often used for gold mining. The importation of mercury should only be for industrial purposes, and well-controlled by the government.
B.N. WAHJU Geologist Jakarta