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TeChNoLogY
Conventional carbon block anodes, assembled with rods
much more efficient system design, and we
are moving to accelerate development to address
the market’s need for a much cleaner,
lower cost approach to light metals pro-duction.
Support by both ARPA-E and MassCEC
validates the transforming nature of this technology,
and its ability to have a major impact
on how the world produces metals.”
Infinium is the sole manufacturer of metals
using Pure Oxygen Anodes, and has already
proven its capability to produce a range of
elements from their oxides, including magnesium
and titanium. Essentially the technique
using Infinium anodes involves separating
the metal production chamber from anode
gases, which eliminates contamination due
to corrosive and toxic anode gas contamination.
This uniquely reduces energy losses in
the electrolysis cell by 60% or more, and also
eliminates the extra collateral costs, energy
consumption and emissions associated with
conventional graphite anode production. The
company spotlights several key advantages
delivered through its technology in aluminium
production: It virtually eliminates CO 2
emissions, which currently amount to 7-10 lb
(3.18-4.54 kg) of CO 2 for every lb (0.454 kg)
of aluminium produced. Production output
per footprint is three to five times higher, and
total production costs are reduced by halving
the energy required and by eliminating the
need for consumable graphite anodes.
According to ARPA-E deputy director
Cheryl Martin, the prime objective of the
agency’s Metals programme is to identify costeffective
and energy-efficient manufacturing
techniques to process and recycle metals domestically.
She says: “We’re very excited to
see how our new awardees working on innovative
metals processing and recycling technologies
could create a breakthrough for
lightweight
vehicles and
energy applications.”
Infinium
is a development-stage
company
commercialising
novel
processes
for primary
production
and recycling
of metals,
chiefly those
with growing
demand in
energy efficiency
and renewable energy technologies.
The first two metals production routes it
investigated were magnesium, for lightweight
fuel-efficient vehicles and aircraft components,
and neodymium, for the magnets in
wind turbines and hybrid / electric vehicles.
Current primary production technologies for
these metals, Infinium recognised, are extremely
pollution-intensive negating much of
their benefit for clean energy and energy efficiency.
Infinium maintains that its new technology
efficiently produces these metals with
zero emissions.
Originally named Metal Oxygen Separation
Technologies (MOxST), the company
changed its name to Infinium in March this
year to reflect its key mission in sustainable
metals. Its facilities in Natick were recently
expanded, doubling its R & D capabilities, and
adding technology personnel.
Advanced electrolytic cell
with power modulation
and heat recovery
Another project has attracted a USD3 million
ARPA-E Award funding under the same
programme umbrella. Alcoa’s Technical
Centre in Pennsylvania is supported for its
work to develop what is said to be a highly
advanced electrochemical system for lowcost
and energy-efficient aluminium production.
The current smelter production process
used is energy intensive and loses a large
amount of thermal energy. This advanced
system will incorporate a high-cycle-life electrode
that is claimed to consumes less electricity
by incorporating innovative technology
which captures and reuses lost heat. If successful,
Alcoa’s electrochemical system will
produce bulk aluminium that requires less energy
with lower carbon emissions compared to
process routes conventionally used.
Dual electrolyte and
electrolytic membrane extraction
The US Gas Technology Institute (GTI) in Des
Plaines, Illinois, will also receive Award funding
to develop a new electrochemical process
that uses abundant, domestic ores to produce
aluminium powder at near room temperature.
Current US domestic aluminium smelters use
expensive foreign-sourced ore to produce
metal, and operate at high temperatures with
a significant amount of thermal energy loss.
GTI’s unique electrochemical process, it is
claimed, will require less energy and produce
fewer carbon dioxide emissions than conventional
smelters.
Conventional anode technology
In the aluminium reduction process conventionally
employed, large carbon block anodes
are used to conduct electricity. During operation
they are consumed, at a rate of around
450 kg a tonne of aluminium produced. The
two types of smelting technology in operation
today – Søderberg and Prebake – are characterised
by the types of anode used in each.
Søderberg smelters use a continuously created
anode, made by the addition of pitch to
the top of the electrolytic cell or ‘pot’. The
heat generated by the reduction process is
used to bake the pitch into the carbon form
required for reaction with alumina, thus recycling
the waste energy in the pot.
Prebake technology employs anodes,
which are baked in large-scale gas-fired ovens
at high temperature before being lowered
into the pot. These are then replaced once
consumed. The efficiency of this technology
compared to Søderberg, combined with its
lower environmental impact, means that prebake
smelters predominate (representing over
90% of worldwide aluminium production),
with all new facilities built today incorporating
this technology.
Ken Stanford, contributing editor
58 ALUMINIUM · 11/2013