Luminophorous powder contains significant concentrations of mercury, which makes it highly hazardous in nature. Mercury can affect most organs in the human body, including the brain, particularly foetuses. Therefore exposure to mercury should be avoided as much as possible. The reason that mercury can so easily affect living organisms is due to three properties:
• highly soluble in water (the mercury from one bulb can pollute 30,000 liters of water)
• volatile (mercury can evaporate into the air and be breathed in by living organisms) and
• Bio-accumulative (once it enters an organism, it is difficult to remove it).
The most common method of removing the mercury from the Luminophorous powder is by a technique called retorting. In this operation, the powder is heated to about 600⁰Cs, and the mercury is evaporated. This mercury vapour is then condensed back to liquid form separate from the powder. The biggest problem with this technique is that the removed mercury remains in a liquid form, in which it is still water-soluble and volatile. Thus, although it is separated from the powder, it is still problematic and a risk to the environment and human lives.
eWaste Africa has a LPX Luminophorous Powder Treatment Plant that uses chemical processes to convert the liquid mercury into a compound called cinnabar. This cinnabar is the form that mercury is found as in nature. The advantage of converting the elemental mercury into cinnabar is that cinnabar is completely insoluble in water, as well as non-volatile. Thus it does not pose a danger to the environment and humans, and can be safely transported for re-use or, if absolutely, necessary, disposed of without danger to the environment.