Chemical Engineering December 2014 - 17

Newsfront
Winning With
electrochemistry
Outotec
New electrode designs
and process technology
promise to reduce energy
costs in traditional
processes
T
hese days, the term electrochemistry
has become almost
synonymous with advanced
batteries and energy-storage
devices, and considerable R&D
efforts abound for both batteries
(Chem. Eng., October 2013, pp.
17-23) and energy storage (Chem.
Eng., December 2011, pp. 19-23).
Nevertheless, traditional, centuryold
electrochemical-based sectors
of the chemical process industries
(CPI) - chlor-alkali, electrowinning
(EW) and primary aluminum
production - have not been idle
bystanders. That's because these
traditional, extremely important
sectors require large amounts of
electrical energy for making their
corresponding products.
At the same time, demand continues
to grow for base elements.
For example, chlorine is used in
many CPI applications, including
agrochemicals, pharmaceuticals,
plastics, water treatment and
many more. Base metals, such as
copper and zinc, continue to be
important for cables, piping and
packaging. And light metals, such
as aluminum and magnesium, are
of growing importance in lightweight
constructions.
To meet these increasing demands,
and to counter ever-growing
energy costs, new materials (for
Figure 1. Shown here is Outotec's Cu electrowinning (EW) anode. EW plants utilize
hundreds to thousands of electrodes to recover high-purity metals
electrodes) and process technology
are being developed to reduce energy
consumption in these traditional
electrochemical industries.
Additional benefits, such as increased
productivity and improved
environmental performance, are
also being realized. Some of these
recent developments - certainly
not all - are presented here.
Electrowinning
Electrowinning (EW) is the main
method used in the mining industry
to recover pure metal products
(Cu, Zn and others) after the metals
have been extracted from ores. Depending
on the metal, the product is
plated onto the cathode of an electrochemical
cell, and either oxygen
(sulfate-based Cu, EW for instance)
or chlorine (chloride-based Cu EW)
is produced at the anode. As in the
chlor-alkali process, EW is energy
intensive, requiring large amounts
of electricity.
Reducing operating costs of the
EW processes was one of the driving
forces for the development of coated
titanium anodes that are now commercially
available from Outotec
Oyj (Espoo, Finland; www.outotec.
com). The anodes were developed by
Republic Alternative Technologies
(Strongville, Ohio) - just acquired
by Outotec in April of this year - in
collaboration with a large U.S. copper
producer. In addition to reducing
the energy consumption in the
EW process, the coated Ti anodes
contain no lead. The presence of
lead in conventional Pb-Ca-Sn anodes
leads to number of problems,
both environmental (sludge formation)
and product quality (lead contamination
at the cathode).
Outotec's anodes (Figure 1) consist
of amorphous nanoparticles
ChemiCal engineering www.Chemengonline.Com DeCemBer 2014 17
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Chemical Engineering December 2014

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