EXTRACTION OF MERCURY

Most of the world's mercury is obtained from its main ore, cinnabar or vermillion with the chemical structure mercury sulphide (HgS). Cinnabar is usually found in a massive or granular form but can also occur as small crystals shown below. This ore is bright red in colour and small droplets of mercury metal can sometimes be found within the ore itself. The main areas for cinnabar mining are in Italy and Spain which provide 50% of the worlds mercury.

CINNABAR IN ITS MASSIVE FORM

http://www.gc.maricopa.edu/earthsci/imagearchive/cinnabar.htm

CINNABAR IN ITS CRYSTAL FORM

    

www.xpsdata.com/ materials_list.htm         www.element51.com/ cinnabar_ru_pic.htm

Mercury can be obtained from cinnabar by heating the cinnabar ore in a current of air and condensing the mercury vapour formed. Due to its relatively low boiling point mercury can be easily purified by vacuum distillation. The reaction of mercury sulphide with oxygen is shown below:

HgS + O2 → Hg + SO2

Other processes for the removal of mercury from cinnabar are also known and the reactions are shown below:

HgS + Fe → Hg + FeS

4HgS + 4CaO → 4Hg + 3CaS + CaSO4