Recycling critical raw materials from waste electronic equipment

More documents

Recommendations

Info

Figure 2: CCFL tubes from a notebook screen (photo Oeko-Institut) 6 Recycling critical raw materials from waste electronic equipment Estimating quantities per unit can only be done using data which is generally available and may display considerable uncertainties, especially for combinations. Nevertheless, an estimate for LCD screens with CCFL background illumination in particular can be made on the basis of the following data: Table 5: Assumptions and data for estimating the percentage of rare earths in the CCFL background illumination of LCD screens Mean weight of a CCFL tube [g] Mean number of tubes per device Notebooks 1 1 Monitors 1.5 6 Televisions 4 15 Percentage weight of luminescent substances in tubes [%] 2.1 Y 8.72 Percentage weight of the luminescent substances [%] Eu 0.64 La 0.54 Ce 0.36 Tb 0.18 Gd 0.05 Pr < 0.01 Data sources: Measurements and estimates made by Hamidovic, 1997, cited in Martens 2011, Guarde et al. 2010.
Recycling critical raw materials from waste electronic equipment Based on these data, the following quantitative estimates can be made: Table 6: Estimated mean weights of rare earth metals in LCD displays with CCFL background illumination Yttrium [mg] Europium [mg] Lanthanum [mg] Cerium [mg] Terbium [mg] Gadolinium [mg] Notebooks 1.8 0.13 0.11 0.076 0.038 0.011 Monitors 16.0 1.20 1.00 0.680 0.340 0.095 Televisions 110.0 8.10 6.80 4.500 2.300 0.630 Newer LCD monitors are sometimes already fitted with background illumination based on white LEDs (see Section 5). In 2010 the market share of LCD monitors and LCD televisions fitted with LEDs was around 30% whereas around 90% of all new notebooks were already equipped with LED background illumination (Young 2011). Like CCFL tubes, white LEDs also make use of a luminescent substance which converts the short-wave light produced in the LED into the visible spectrum. The support matrix is usually made from yttrium aluminum garnet (YAG) with substantial admixtures of gadolinium. The doping consists of a few percent by weight of cerium and sometimes europium. The actual LED semiconductor chip which produces the light is composed of indium gallium nitride (see also Section 5.1). This results in a somewhat different composition for the rare earths in LCD monitors, LCD televisions and notebooks with LED background illumination in comparison to Table 6, as shown in Table 8 (indium and gallium are included in this list). This table makes use of the proportions of critical metals in white LEDs specified in Table 7 (see also Table 30 in Section 5.1). The number of white LEDs in a monitor required for the projection is a quantity which varies depending on the manufacturer and can therefore only be estimated for a general survey. Based on model data in Young (2011), estimates of 100 LEDs for an LCD PC monitor, 150 LEDs for an LCD television and 50 LEDs for a notebook display have been made (see Table 7). 7
Page 1: Recycling critical raw materials fr
Page 4 and 5: IV Recycling critical raw materials
Page 6 and 7: VI Recycling critical raw materials
Page 8 and 9: VIII Recycling critical raw materia
Page 10 and 11: Figure 1: Global end-of-life recycl
Page 12 and 13: 4 Recycling critical raw materials
Page 22 and 23: Figure 4: Sales development of TV s
Page 46 and 47: 4.1 Precious metals 38 Recycling cr
Page 56 and 57: Figure 23: LED components and the m
Page 64 and 65:
56 Recycling critical raw materials
Page 66 and 67:
Page 68 and 69:
Page 70 and 71:
Page 72 and 73:
Page 74 and 75:
Page 76 and 77:
Page 78 and 79:
Page 80 and 81:
Page 82 and 83:
8 References 74 Recycling critical
Page 84 and 85:
Page 86 and 87:
Page 88:
show all

Recycling critical raw materials from waste electronic equipment

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?