9 Sustainable Attainment of Solar E-waste …
225
recycling processes relating to each item. “The frameless PV module consists of
the active silicon cell contained in an EVA polymer layer that allows the cell to be
laminated onto the back sheets of hard polymer and onto the front sheet of glass”
[7].
“Recycling of solar cells requires placing the components in a smelter or acid bath
to recover the elements, including selenium (Se), indium (In), and gallium (Ga). The
glass is cleaned and collected by thermal decomposition; dissolution of solvent or
acid to eliminate any residual PV layers” [24]. “With the aid of a hammer mill, the
recycling process begins with the shredding of the PV modules into large parts and
then into small fragments (5 mm or less). The semiconductor films are then removed
over the next 4–6 h in a slow leaching drum. The remaining glass is exposed to
a combination of sulfuric acid (H 2 SO 4 ) and hydrogen peroxide (H 2 O 2 ) for optimal
solid-liquid ratio. Following that, the isolation from the glass is repeated. A vibrating
screen is used in the next step to isolate the glass from the larger pieces of ethylene
vinyl acetate (EVA), via. After cleaning it the glass is sent for recycling. Sodium
hydroxide is used to deposit the metal compounds, after which they are transported
to another industry where they can be processed into raw materials of semiconductor
quality for use in the modern solar PV modules. This entire process recovers 90% of
the glass used in the manufacture of new products, and 95% of the semiconductor
materials and metals used in new solar PV modules” [21] (Fig. 9.5).
9.3.1 Advanced Recycling Technologies
“Advanced or specialized PV recycling uses a combination of mechanical, thermal,
and chemical processes to recover most materials including glass, aluminium, copper,
silicon, silver, lead, and tin. The polymer fraction remains unrecoverable, 8-10 per
cent by weight, and must be landfilled and incinerated” [17].
Various chemical, thermal, and a mix of mechanical methods or processes of
advanced or specialized levels for PV recycling to recover most material, including
metals, are used. Even then, the polymer fraction has to be landfilled and incinerated,
8–10% by weight, is unrecoverable.
The advanced recycling method consists of three processes:
(1) Thermal Process: Here, the components are passed through the combustion
chamber and through the process of pyrolysis (thermal decomposition in an
inert atmosphere), etching (the process of cutting metal into unprotected pieces
by using strong acid or mordant), the recovered metals from PV cells are sent
to metal refinery for metal recovery.
(2) Mechanical Process: In the mechanical process, the crushing or grinding method
is used to sort the waste by size and magnetism, which goes to waste along with
glass if the waste is nonmagnetic. Other processes scape and cut the encapsulation layer for the solvent treatment of components so that metal components
obtain can be sent to the metal refinery for metal purification processes.
225
recycling processes relating to each item. “The frameless PV module consists of
the active silicon cell contained in an EVA polymer layer that allows the cell to be
laminated onto the back sheets of hard polymer and onto the front sheet of glass”
[7].
“Recycling of solar cells requires placing the components in a smelter or acid bath
to recover the elements, including selenium (Se), indium (In), and gallium (Ga). The
glass is cleaned and collected by thermal decomposition; dissolution of solvent or
acid to eliminate any residual PV layers” [24]. “With the aid of a hammer mill, the
recycling process begins with the shredding of the PV modules into large parts and
then into small fragments (5 mm or less). The semiconductor films are then removed
over the next 4–6 h in a slow leaching drum. The remaining glass is exposed to
a combination of sulfuric acid (H 2 SO 4 ) and hydrogen peroxide (H 2 O 2 ) for optimal
solid-liquid ratio. Following that, the isolation from the glass is repeated. A vibrating
screen is used in the next step to isolate the glass from the larger pieces of ethylene
vinyl acetate (EVA), via. After cleaning it the glass is sent for recycling. Sodium
hydroxide is used to deposit the metal compounds, after which they are transported
to another industry where they can be processed into raw materials of semiconductor
quality for use in the modern solar PV modules. This entire process recovers 90% of
the glass used in the manufacture of new products, and 95% of the semiconductor
materials and metals used in new solar PV modules” [21] (Fig. 9.5).
9.3.1 Advanced Recycling Technologies
“Advanced or specialized PV recycling uses a combination of mechanical, thermal,
and chemical processes to recover most materials including glass, aluminium, copper,
silicon, silver, lead, and tin. The polymer fraction remains unrecoverable, 8-10 per
cent by weight, and must be landfilled and incinerated” [17].
Various chemical, thermal, and a mix of mechanical methods or processes of
advanced or specialized levels for PV recycling to recover most material, including
metals, are used. Even then, the polymer fraction has to be landfilled and incinerated,
8–10% by weight, is unrecoverable.
The advanced recycling method consists of three processes:
(1) Thermal Process: Here, the components are passed through the combustion
chamber and through the process of pyrolysis (thermal decomposition in an
inert atmosphere), etching (the process of cutting metal into unprotected pieces
by using strong acid or mordant), the recovered metals from PV cells are sent
to metal refinery for metal recovery.
(2) Mechanical Process: In the mechanical process, the crushing or grinding method
is used to sort the waste by size and magnetism, which goes to waste along with
glass if the waste is nonmagnetic. Other processes scape and cut the encapsulation layer for the solvent treatment of components so that metal components
obtain can be sent to the metal refinery for metal purification processes.