172
Studies on the recovery of materials have discussed several techniques, such as:
– Acid leaching to recover powder gallium and indium generated during the metalorganic chemical vapour deposition (MOCVD) process
– Pyrolysis, physical degradation, and vacuum separation to recover gallium and
indium generated from LED chips
– Bacterial leaching to recover gallium from gallium nitride (GaN)
– Bacterial leaching to recover gallium from gallium arsenide (GaAs)
– Mechanical oxidation and leaching of the powder produced during metal-organic
chemical vapour deposition (MOCVD) to recover gallium
– Leaching, milling, and annealing to recover gallium from gallium nitride (GaN)
from powder waste generated during the manufacture of LEDs
9.6.1 Bulbs
The recyclability of materials depends on existing technologies and methodologies.
But the economic, geological, and geopolitical feasibility of raw materials and market prices also influences the parameter. Recycling methods become relevant in a
scenario of dwindling natural resources, which means that the recovery of even the
smallest fractions will be a question of technological feasibility. This, in turn, means
that the amounts and storage of critical materials become important factors in the
recycling of LEDs (Gassmann et al. 2016).
Gassmann et al. (2016) introduced a method to recycle LED bulbs that use coarse
milling followed by segregation of materials based on their characteristics. Metals
may be separated by magnetization, while ceramics and plastics could be sorted
using the difference in density. Grain size distribution may also be used, and LEDs
are easily detected by irradiation with ultraviolet (UV) light. The electrical and
electronic components may be transported to specialized recycling organizations
that recover precious metals. The authors also concluded that LEDs could be considered impurities that may be collected and stored, while no suitable method is
available to recover critical materials. Due to the small size, LEDs do not require
much storage space (Gassmann et al. 2016). The flow proposed by the authors is
shown in Fig. 9.11.
9.6.2 Other LED Devices
LEDs are produced as a wide variety of items, such as superthin TV sets, cell
phones, lighting fixtures, outdoors, and laptops.
TV sets and cell phones are complex devices when it comes to recycling since they
present a large number of different materials associated with LEDs. Therefore, these
devices are considered complex waste, for which no technique has been developed to
recycle their components. In addition, these products generate considerable amounts
of waste, mainly due to the fast evolution of technology.
E. C. A. dos Santos et al.
Studies on the recovery of materials have discussed several techniques, such as:
– Acid leaching to recover powder gallium and indium generated during the metalorganic chemical vapour deposition (MOCVD) process
– Pyrolysis, physical degradation, and vacuum separation to recover gallium and
indium generated from LED chips
– Bacterial leaching to recover gallium from gallium nitride (GaN)
– Bacterial leaching to recover gallium from gallium arsenide (GaAs)
– Mechanical oxidation and leaching of the powder produced during metal-organic
chemical vapour deposition (MOCVD) to recover gallium
– Leaching, milling, and annealing to recover gallium from gallium nitride (GaN)
from powder waste generated during the manufacture of LEDs
9.6.1 Bulbs
The recyclability of materials depends on existing technologies and methodologies.
But the economic, geological, and geopolitical feasibility of raw materials and market prices also influences the parameter. Recycling methods become relevant in a
scenario of dwindling natural resources, which means that the recovery of even the
smallest fractions will be a question of technological feasibility. This, in turn, means
that the amounts and storage of critical materials become important factors in the
recycling of LEDs (Gassmann et al. 2016).
Gassmann et al. (2016) introduced a method to recycle LED bulbs that use coarse
milling followed by segregation of materials based on their characteristics. Metals
may be separated by magnetization, while ceramics and plastics could be sorted
using the difference in density. Grain size distribution may also be used, and LEDs
are easily detected by irradiation with ultraviolet (UV) light. The electrical and
electronic components may be transported to specialized recycling organizations
that recover precious metals. The authors also concluded that LEDs could be considered impurities that may be collected and stored, while no suitable method is
available to recover critical materials. Due to the small size, LEDs do not require
much storage space (Gassmann et al. 2016). The flow proposed by the authors is
shown in Fig. 9.11.
9.6.2 Other LED Devices
LEDs are produced as a wide variety of items, such as superthin TV sets, cell
phones, lighting fixtures, outdoors, and laptops.
TV sets and cell phones are complex devices when it comes to recycling since they
present a large number of different materials associated with LEDs. Therefore, these
devices are considered complex waste, for which no technique has been developed to
recycle their components. In addition, these products generate considerable amounts
of waste, mainly due to the fast evolution of technology.
E. C. A. dos Santos et al.