152
With a view to averting the unfavourable impacts of smelting process utilized in
the recovery of copper from metal powders of waste printed wiring boards rich in
tin, Yang et al. (2017) have proposed hydrometallurgy as an effective technique that
selectively extracts tin as well as its associated metals. For instance, alkaline pressure oxidation leaching parameters on metal conversion have been systematically
investigated. The results showed that Sn, Pb, Al and small amounts of Zn in the
metal powders were leached out, leaving a copper residue (Yang et al. 2017). The
use of different cyanide or non-cyanide leaching techniques to recover precious and
other valuable metals has been reported (Akcil et al. 2015). A novel methodology,
using ammonium persulfate ((NH 4 ) 2 S 2 O 8 ), to recover gold from waste E-waste has
been assayed. The findings presented by Alzate et al. (2016) revealed that (NH 4 ) 2 S 2 O 8
in aqueous media could be used to recover gold from E-waste. According to Sun
et al. (2015), a new electrodeposition process has been proven feasible with high
efficiency during copper recovery from E-waste. The leaching solutions have been
analysed by ICP in order to detect the most important metals for the electrodeposition (Lekka et al. 2015). The use of hydrometallurgical techniques such as spontaneous reduction polyaniline coating of cotton fibre has been demonstrated as
effective tools in gold recovery from electronic scrap (Lekka et al. 2015). Soare
et al. (2016) and Popescu et al. (2018) have shown that ionic liquids can be deployed
to anionically dissolve E-waste in order to recover metals such as Sn, Pb Au and Ag
from multi-component alloy.
8.1.3.1.3 Biohydrometallurgy: An Eco-friendly Approach for Metal Recovery
Biohydrometallurgy has been considered as an important means of metal recovery
from waste due to its cost-effectiveness and eco-friendly nature. It is also known as
to conserve energy due to its ease in operation compared to other recovery techniques. Through bioleaching and oxidation reactions, different chemolithotrophic
bacteria such as Acidithiobacillus thiooxidans and A. ferrooxidans have been successfully used as bioleaching agents for metal recovery from E-wastes (Chauhan
et al. 2018).
An acclimatized consortium of either Thermoplasma acidophilum and
Sulfobacillus thermosulfidooxidans or S. acidophilus and S. thermosulfidooxidans
was used to bioleach more than 75 % of Zn
2+
, Ni
2+
, Cu
2+
and Al
3+
from E-waste
pretreated with iron sulphide and elemental sulphur (Ilyas et al. 2013). Using A.
thiooxidans (DSM 9463), bioleaching of about 99 % of neodymium, emporium and
cerium and 80 % of yttrium and lanthanides from a solution of shredded dust of
electronic scraps was accomplished. Also, Pseudomonas putida WSC361 (cyanide
producer) in a further step sequestered about 45 % Au from shredded dust already
bioleached with A. thiooxidans (Marra et al. 2018). Priya and Hai (2018) utilized
exopolymeric substances produced by A. ferrooxidans supplemented with lemon
juice to recover nickel, copper, lead and zinc from electronic-waste. Heydarian et al.
(2018) demonstrated that A. ferrooxidans and A. thiooxidans were shown to be
effective bioleaching tools for the recovery of cobalt, nickel and lithium from spent
C. O. Onwosi et al.
With a view to averting the unfavourable impacts of smelting process utilized in
the recovery of copper from metal powders of waste printed wiring boards rich in
tin, Yang et al. (2017) have proposed hydrometallurgy as an effective technique that
selectively extracts tin as well as its associated metals. For instance, alkaline pressure oxidation leaching parameters on metal conversion have been systematically
investigated. The results showed that Sn, Pb, Al and small amounts of Zn in the
metal powders were leached out, leaving a copper residue (Yang et al. 2017). The
use of different cyanide or non-cyanide leaching techniques to recover precious and
other valuable metals has been reported (Akcil et al. 2015). A novel methodology,
using ammonium persulfate ((NH 4 ) 2 S 2 O 8 ), to recover gold from waste E-waste has
been assayed. The findings presented by Alzate et al. (2016) revealed that (NH 4 ) 2 S 2 O 8
in aqueous media could be used to recover gold from E-waste. According to Sun
et al. (2015), a new electrodeposition process has been proven feasible with high
efficiency during copper recovery from E-waste. The leaching solutions have been
analysed by ICP in order to detect the most important metals for the electrodeposition (Lekka et al. 2015). The use of hydrometallurgical techniques such as spontaneous reduction polyaniline coating of cotton fibre has been demonstrated as
effective tools in gold recovery from electronic scrap (Lekka et al. 2015). Soare
et al. (2016) and Popescu et al. (2018) have shown that ionic liquids can be deployed
to anionically dissolve E-waste in order to recover metals such as Sn, Pb Au and Ag
from multi-component alloy.
8.1.3.1.3 Biohydrometallurgy: An Eco-friendly Approach for Metal Recovery
Biohydrometallurgy has been considered as an important means of metal recovery
from waste due to its cost-effectiveness and eco-friendly nature. It is also known as
to conserve energy due to its ease in operation compared to other recovery techniques. Through bioleaching and oxidation reactions, different chemolithotrophic
bacteria such as Acidithiobacillus thiooxidans and A. ferrooxidans have been successfully used as bioleaching agents for metal recovery from E-wastes (Chauhan
et al. 2018).
An acclimatized consortium of either Thermoplasma acidophilum and
Sulfobacillus thermosulfidooxidans or S. acidophilus and S. thermosulfidooxidans
was used to bioleach more than 75 % of Zn
2+
, Ni
2+
, Cu
2+
and Al
3+
from E-waste
pretreated with iron sulphide and elemental sulphur (Ilyas et al. 2013). Using A.
thiooxidans (DSM 9463), bioleaching of about 99 % of neodymium, emporium and
cerium and 80 % of yttrium and lanthanides from a solution of shredded dust of
electronic scraps was accomplished. Also, Pseudomonas putida WSC361 (cyanide
producer) in a further step sequestered about 45 % Au from shredded dust already
bioleached with A. thiooxidans (Marra et al. 2018). Priya and Hai (2018) utilized
exopolymeric substances produced by A. ferrooxidans supplemented with lemon
juice to recover nickel, copper, lead and zinc from electronic-waste. Heydarian et al.
(2018) demonstrated that A. ferrooxidans and A. thiooxidans were shown to be
effective bioleaching tools for the recovery of cobalt, nickel and lithium from spent
C. O. Onwosi et al.