Flat Screen Fractions
The light-conducting and -diffusion layer in an LCD or LED monitor is made of high-quality plastic which can possibly be commercialized separately from common plastics. If relevant amounts of this valuable material can be gathered, a potential way to sell it are online recycling markets. As shown in the image, the layer is a thick layer which is highly transparent. It is directly connected to the light source (backlight of the LCD).
Large liquid crystal layers are mainly used in computer and TV monitors, smaller ones are found in printers, fixed line telephones, photo cameras etc. Despite their size, their properties are the same.
Liquid Crystal Layer
Liquid crystal displays rely on the light modulating properties of certain liquid crystalline substances. This liquid crystal layer is located between two (dark) polarizers, which is enclosed by several other, usually white or transparent plastic layers (see above).
Liquid crystal is not just a liquid, it is actually a state in-between liquid and solid.
The optical properties of the liquid crystal layer are modified by applying an electric field to it. Liquid crystals do not emit light directly and are therefore dependent on a light source (in general cold cathode fluorescent lamps or LEDs). The CCFLs are hazardous and must therefore be treated cautiously (see below and Chapter 3.5. Lamps).
Store the LCD layers in a container. If possible, avoid breakage of the layers.
Liquid crystal layers contain indium, which is a valuable rare metal, increasingly in short supply: In the ITO (indium tin oxide) electrodes of the liquid crystal module, small amounts of indium (In) can be found. Due to the small volume of the liquid crystal layer and the potentially rising price of indium, it is recommended to store them for future indium recovery.
Another option is the disposal of the liquid crystal module (without CCFL) in a landfill or its ontrolled incineration.
Cold Cathode Fluorescent Lamp (CCFL)
The most common way to illuminate the liquid crystal layer is to use a cold cathode fluorescent lamp (CCFL). They increase the luminosity of the screen. They are found in laptops, TVs, and other devices with LCDs (photocopy machine display, mobile phones, etc.). CCFLs are classified hazardous due to their mercury (Hg) content and the phosphor layer. The mercury is applied to the fluorescent tubes in a gaseous form. If it is ionised by electricity, it emits.
UV light, which in turn is transformed by the phosphor layer into visible light. Two CCFLs are to be found inside the display frame, usually on the upper and bottom parts.
Depollution should be done in a fume hood with an air pollution control system to avoid mercury vapour exposure to the workers when a backlight accidentally breaks.
The fluorescent tubes are very thin and fragile, and should not break during dismantling. Access to them is possible only through careful manual dismantling of the frame. Once it is located, the fluorescent tube can be disconnected easily by cutting the alimentation wires. Be careful, as some fluorescent tubes are, in addition, stuck to the support.
Usually, backlights from TV monitors are more difficult to remove than those in computer monitors, as they are larger. If possible the breaking of the fluorescent tubes should be avoided. In case of breaking, fluorescent tubes should be stored very carefully in a closed box or barrel that prevents the release of Hg-vapour.