152
5 Recovery of Metals from Electronic Waste
difficult separation from the effluent. Thus, the immobilized particles are usually
preferred [20]. Chitosan, which is a deacetylated derivative of chitin, is the most
common biopolymer used for the biosorption of precious metals. The amino acids
of chitosan have the ability to be protonated easily in an acidic environment and thus
making the electrostatic forces prominent [37]. The mechanism of metal binding in
the biosorption process differs from one system to another with the same metal and
a different biomass type or form [37].
5.9 Industrial Applications of E-Waste Recycling
Metallurgical methods are the most widely used industrial processes for the recovery
of metals from e-waste. Table 5.2 shows a list of some of the industrial e-waste recycling plants around the world. Europe has three popular smelting units for treating
e-waste: Umicore N.V., Aurubis A.G. and Boliden. The Umicore has the world’s
largest waste recycling facility for the recovery of precious metals in Hoboken,
Belgium and uses a mixture of pyrometallurgical, hydrometallurgical, and electrochemical processes. They are specialized in the recovery of gold and silver, precious
metals and other metals from different residues including e-waste. The Umicore
plant uses the ISASMELT
TM technology in which a vertical shaft furnace is fed
with electronic waste from the top along with air enriched in oxygen. The process
takes place at 1200 °C and the melt is mixed by the process gases to help the fast
equilibration of the melt. The precious metals are dissolved in molten copper and
are tapped from the bottom of the furnace. The copper then goes through further
hydrometallurgical/electrochemical refining processes and the precious metals are
recovered by electrorefining of anode slimes [16, 21]. The Aurubis plant is located
in Germany and produces high-purity, high-quality copper from copper concentrates
and other waste materials. This plant also uses the ISASMELT
TM technology and
produces more than a million copper cathodes in the forms of continuous cast rod,
specialty wire, shapes, rolled products, strip and profiles [16, 21]. The Boliden plant
in Skelleftehamn, Sweden, uses Rönnskär Smelters for the recovery of metals from
e-waste. The process consists of drying, roasting, smelting, converting and refining
steps. High-grade e-waste is directly sent to the converting stage, while the lowgrade e-waste is first treated in Kaldo rotary furnace for drying, roasting, smelting
treatments. The Kaldo furnace operates at 1200 °C and is fed with a blend of feeding
materials consisting of e-waste and lead concentrates. The product of Kaldo furnace
is a mixed copper alloy, and then sent to the copper converter for the recovery of
metals [16, 20, 21].
The Noranda process in Quebec, Canada, is another pyrometallurgical method in
which the material is fed into the molten bath at 1250 °C equipped with supercharged
oxygen (up to 39% oxygen) injection for keeping the temperature constant. The impurities such as iron, lead and zinc are collected in the slag phase and the precious metals
are separated in the molten copper. The molten copper phase is further processed
in copper converter and anode furnace, where it is refined to copper anodes with
5 Recovery of Metals from Electronic Waste
difficult separation from the effluent. Thus, the immobilized particles are usually
preferred [20]. Chitosan, which is a deacetylated derivative of chitin, is the most
common biopolymer used for the biosorption of precious metals. The amino acids
of chitosan have the ability to be protonated easily in an acidic environment and thus
making the electrostatic forces prominent [37]. The mechanism of metal binding in
the biosorption process differs from one system to another with the same metal and
a different biomass type or form [37].
5.9 Industrial Applications of E-Waste Recycling
Metallurgical methods are the most widely used industrial processes for the recovery
of metals from e-waste. Table 5.2 shows a list of some of the industrial e-waste recycling plants around the world. Europe has three popular smelting units for treating
e-waste: Umicore N.V., Aurubis A.G. and Boliden. The Umicore has the world’s
largest waste recycling facility for the recovery of precious metals in Hoboken,
Belgium and uses a mixture of pyrometallurgical, hydrometallurgical, and electrochemical processes. They are specialized in the recovery of gold and silver, precious
metals and other metals from different residues including e-waste. The Umicore
plant uses the ISASMELT
TM technology in which a vertical shaft furnace is fed
with electronic waste from the top along with air enriched in oxygen. The process
takes place at 1200 °C and the melt is mixed by the process gases to help the fast
equilibration of the melt. The precious metals are dissolved in molten copper and
are tapped from the bottom of the furnace. The copper then goes through further
hydrometallurgical/electrochemical refining processes and the precious metals are
recovered by electrorefining of anode slimes [16, 21]. The Aurubis plant is located
in Germany and produces high-purity, high-quality copper from copper concentrates
and other waste materials. This plant also uses the ISASMELT
TM technology and
produces more than a million copper cathodes in the forms of continuous cast rod,
specialty wire, shapes, rolled products, strip and profiles [16, 21]. The Boliden plant
in Skelleftehamn, Sweden, uses Rönnskär Smelters for the recovery of metals from
e-waste. The process consists of drying, roasting, smelting, converting and refining
steps. High-grade e-waste is directly sent to the converting stage, while the lowgrade e-waste is first treated in Kaldo rotary furnace for drying, roasting, smelting
treatments. The Kaldo furnace operates at 1200 °C and is fed with a blend of feeding
materials consisting of e-waste and lead concentrates. The product of Kaldo furnace
is a mixed copper alloy, and then sent to the copper converter for the recovery of
metals [16, 20, 21].
The Noranda process in Quebec, Canada, is another pyrometallurgical method in
which the material is fed into the molten bath at 1250 °C equipped with supercharged
oxygen (up to 39% oxygen) injection for keeping the temperature constant. The impurities such as iron, lead and zinc are collected in the slag phase and the precious metals
are separated in the molten copper. The molten copper phase is further processed
in copper converter and anode furnace, where it is refined to copper anodes with