Chemical Engineering June 2010 - 11

Edited by Gerald Ondrey
June 2010
d.c. power supply
Electrochemistry regenerates H2SO4
and recovers iron from industrial wastes
A
n electrochemical process for recovering
sulfuric acid and metallic iron from ironrich
sulfate wastes, such as spent pickling
liquors and pregnant leach solutions generated
in minerals and metals processing,
has been patented by François Cardarelli,
an independent researcher located in Montreal,
Canada (www.francoiscardarelli.ca).
Cardarelli says the process offers a green
solution to the processing of these wastes,
most of which currently end up in landfills
or disposal piles.
In Cardarelli's process, an iron-rich sulfate
solution is pH-adjusted to below 3.0 by
adding a neutralizing agent, such as sodium
hydroxide, and fed to the cathode side of
an electrolytic cell (diagram). The adjustment
is necessary to avoid the evolution of
hydrogen at the cathode, a competing process,
says Cardarelli. Iron deposits on the
titanium cathode (a material chosen to prevent
H2 evolution), while sulfate anions migrate
through an ion-exchange membrane
to the anode. Initially there is a 10% solution
of H2SO4 on the anode side. Acid removal
starts when the H2SO4 concentration
reaches about 30%. Oxygen evolves from the
iridium dioxide-coated Ti anode.
Iron depleted
solution
Iron metal
deposit
Sulfate
anions
Titanium
cathode (-)
Iron-rich
metal sulfate
solution
Catholyte
2Fe2++ 4e- → 2Fe(s)
Anolyte
2H2O→ O2(g) + 4H+ + 4e2FeSO4
+ 2H2O→ 2Fe(s) + 2H2SO4 + O2(g)
Cardarelli has tested the process, using
1-ft2 electrodes, and is negotiating with potential
industrial partners to do pilot tests
with units containing about 20 12-ft2 electrodes.
No cost figures are available as yet, but
Cardarelli says the economics of the process
depend on disposal costs, the costs of H2SO4
and scrap iron, and the utilization of oxygen
onsite. He notes that scrap iron currently
sells for about $300 per metric ton (m.t.) in
the U.S. and up to $450/m.t. in Europe.
A device to measure density and viscosity non-invasively
ltimo Measurement (Providence,
U
R.I.;
www.ultimompd.com) has developed technology
for measuring density and viscosity
of process fluids, loose solids and mixtures
non-invasively - a percussion-based device
that can be mounted on the outside of process
tanks, pipes or other vessels. The device
strikes a vessel's outside wall, exciting the
content material, then senses the resulting
vibrations, which are related to the density
and viscosity of the content material by a
complex combination of physical laws. Proprietary
software then analyzes the oscillation
data with specialized algorithms that
relate the material's oscillation signature
with its density or viscosity, explains Ultimo
CEO Frank Lubrano. The software is adaptive
and self-learning, and can discriminate
between valuable and ambient vibrations.
The system's ability to collect information
from outside the vessel wall lengthens its
service life, since it never contacts the mateNote:
For more information, circle the 3-digit number
on p. 62, or use the website designation.
rial being measured. Also, the adaptive nature
of the striker device and analysis algorithms
make the measurement tool effective
with virtually all types of liquids, slurries
and loose solids, and with any type or size of
storage vessels or conduits constructed from
a wide range of metals, fiberglass or plastic.
Lubrano points out that his company's
device allows processors to obtain early
data on viscosity and density, which can
reduce plant waste, save resources and improve
product quality. He also notes that in
field-testing, the device has achieved precision
of 0.1% on light powders and 0.5% on
polymer materials.
The technology was originally applied as
a level measurement tool, but the company
has adapted its core technology for density
and viscosity analyses. Ultimo has produced
prototypes of the measurement devices and
is looking to license its proprietary technology
to partners.
An new olefins process
A 40,000-m.t./yr demonstration
plant for a new process that produces
olefins by catalytic cracking
of paraffins-rich naphtha will
be started up in October by SK
energy (Seoul, South Korea;
www.skenergy.com) at Ulsan,
South Korea. Developed jointly
with KBR (Houston; www.kbr.
com), the Advanced Catalytic
Olefin (ACO) process uses a
proprietary granular zeolite
catalyst in a fluidized bed.
The olefins yield is about 65%
and the propylene:ethylene ratio
is 1:1, versus about 50% and
0.5:1 for naphtha steam crackers,
says Tim Challand, president
of KBR Technology. The
process temperature is about
650°C, compared to about
850°C for a steam cracker. KBR
is the exclusive, worldwide
licensor of the technology. (For
more details on ACO, see CE,
March 2007, p. 20).
LiPF6 made in the U.S.A.
Honeywell (Morristown, N.J.;
www.honeywell.com) has signed
a contract with the U.S. Dept. of
Energy (DOE; Washington, D.C.)
for a $27.3-million grant to produce
high-purity lithium hexafluorophosphate
- a conductive
salt that is one of four critical
(Continues on p. 12)
CHEMiCAl ENgiNEERiNg WWW.CHE.COM JUNE 2010 11
Dimensionally
stable anode
(DSA -O2 ) (+)
Anolyte
in
Anion
exchange
membrane
Oxygen gas
Water
make-up
Anolyte
out
http://www.francoiscardarelli.ca http://www.skenergy.com http://www.kbr http://www.ultimompd.com http://www.honeywell.com http://WWW.CHE.COM
Chemical Engineering June 2010

Table of Contents for the Digital Edition of Chemical Engineering June 2010
