Safely disposing of mercury
It's toxic, heavy, and it's still hanging around in old bulbs and thermometers. And if the metal passes into the environment, humans and animals get hurt. Here's how to ditch your mercury safely.
Beautiful, but deadly
Humans have been using mercury since ancient times. In the Middle Ages, it was used in alchemy and medicine. It was only in the modern period that it became clear that the metal is highly poisonous.
The paradox of energy-saving bulbs
There's also mercury in fluorescent lighting. Although they save energy, disposal can be a problem. Energy-saving bulbs should not be thrown away with other waste, due to the tiny amount of mercury they contain.
Into the shredder...
A forklift operator at the DELA recycling company in Essen, Germany, dumps a load of compact fluorescent tubes into a shredder. In order to prevent mercury from escaping, a filtering ventilation system sucks the air away.
... then the silo ...
The shredded compact fluorescent tubes are stored in a silo until a spiral conveyor carefully carries them to a glass-washing area.
... and into in the washing machine
Workers wash masses of broken glass from the shredded lamps to recover luminescent material and mercury from the glass shards.
Pure glass
Glass from lightbulbs is considered valuable in industrial processes, since it can withstand high temperatures and varying levels of pressure. Producers of the bulbs use the purest possible materials.
Vacuum drying
The glass washing process leaves behind a sludge with a high mercury content. Mercury is distilled from this, just like in a liquor distillery.
Valuable illuminant
The pure illuminant is returned to lightbulb producers. They gladly pay for it, because it contains the rare earth elements yttrium and europium.
Distillate
From the vacuum dryer comes pure mercury. Since the metal is quite dense, it weighs 1.7 times as much as the same volume of iron. The amount shown in the jar here is from 500,000 compact fluorescent light bulbs.
Detox
Sulfur is directed to the left part of this machine, while from above comes the liquid mercury. The combination produces mercury sulfide, which has a very stable composition and is no longer poisonous.
Red mercury sulfide
Mercury sulfide can be disposed of through storage in old mines. It's used, along with rock filling, to fill in old mine shafts and stabilize them.
Disposal - as art
This piece of modern art, made from mercury sulfide, hangs on the wall at the DELA recycling company in Dorsten, Germany.