One of the biggest mines in the world (Almaden in Spain) has virtually ceased operations as the increasingly common recycling of mercury in a falling market is making primary extraction somewhat redundant. World production has been steadily falling since the mid-eighties.
Mercury comes from an ore called cinnabar, which is in fact a sulphide of mercury (HgS) .
Mercury is a base material; it is an element and cannot be decomposed. Its unique properties make it an essential element for numerous applications. Whether in qualitative or in ecological terms, vacuum distillation has a clear advantage over chemical treatment processes producing effluent that it is always difficult to dispose of.
To avoid any possibility of discharge into the environment, we can recycle and reuse this metal almost entirely. We have several systems of vacuum distillation, including a rotary continuous loading primary vacuum reactor which gives a purity of 99.9%. It is here that we recover 5 to 10 kg of residues a year. These impurities in the mercury are usually traces of various metals which are recovered in the form of solid nodules in our primary distillation reactor.
Continuous loading rotary vacuum reactor: at a low distillation temperature, this avoids the entrainment of the other elements contained in the contaminated mercury.
To obtain distinctly higher qualities, successive distillations are carried out on a high-vacuum Pyrex distillation line producing 99.99% to minimum 99.99999% mercury.
Further refinement of the reactor will shortly make it possible to distil porous mercury-impregnated samples derived from porosimetric analysis.
Our customised methods of refining contaminated mercury enable us to appreciably reduce losses of metal to the environment, although everyone needs to be well aware that it is up to them to help protect the environment through the reuse of base materials.
