Chemical Engineering August 2014 - 12

ChementatoR
This chloride leaching process recycles resources
O
utotec Oyj (Espoo, Finland; www.outotec.com)
has developed a new chloridebased
leaching process for recovering
nickel from nickel matte - a commercial
intermediate product of nickel smelting
that contains about 65% of nickel. Developed
since the 1980s, originally for Cu
recovery and since extended to Ni, Zn
and Au, the Outotec Nickel Matte Chloride
Leaching process is a more resourceefficient
and environmentally sustainable
option for Ni refining compared to
existing leaching processes, says Kaarlo
Haavanlammi, technology manager -
Nickel Hydrometallurgy. Besides Ni
matte, the process can be modified to
treat all sulfidic nickel concentrates, as
well as low-grade sulfides (<5% Ni), says
Haavanlammi.
The new process (flowsheet) is based
on a calcium chloride solution, which
enables easy acid (HCl) and base (NH3)
regeneration in the process. Leaching is
performed in acidic conditions (pH low
enough to prevent Fe precipitation), using
HCl solution from acid regeneration, and
the addition of O2 (to prevent H2 formation).
Leaching is performed in multiple
steps at near boiling point temperatures
and atmospheric pressure for 10-15 h.
After leaching, the metals (Fe, Cu, Co and
Ni) are recovered from the chloride solution
by solvent extractions, and then purified
by electrowinning. NH4Cl produced
in the extraction raffinate is regenerated
into NH3, and the CaCl2 solution from
Heavy-metal RecoveRy
(Continued from p. 11)
cury, manganese, molybdenum and more.
Unlike other metal-removal methods,
the Enviro-Clean process is not based on
chemical precipitation or regeneration,
both of which generate hazardous waste
streams that require further treatment.
The Enviro-Clean process produces no
hazardous waste or sludge, instead resulting
in a recyclable effluent, along
with its recovered metallic products. This
effluent can meet very low discharge limits
for heavy-metal content, achieving
less than 10 parts per billion (ppb).
LES stresses that the process is quite
versatile, because most commercially
available activated-carbon products can
be used as feedstock for the modular
unit. Additionally, the process can be either
retrofited into an existing layout or
Oxygen
Leach
residue
Leaching
Matte
Metals as chlorides
Limestone
Iron
removal
Goethite
NH3 (aq)
Copper
solvent
extraction
Cobalt
solvent
extraction
NH4Cl, CaCl2
Nickel
solvent
extraction
NH3 (g)
Condensation
Ammonia
regeneration
Ca(OH)2
CaCl2, HCl
Offgas to
scrubbing
Acid
regeneration
H2SO4
Gypsum
CaCl2
Copper EW
Cobalt
precipitation
Copper
CoS or CoCO3
NH3 regeneration is routed to acid regeneration,
where sulfuric acid is added and
gypsum is precipitated. HCl generated in
this step is reused for leaching.
In laboratory scale piloting, this chloride
leaching process has achieved recoveries
of 99% (Ni and Co) and 98% (for Cu),
says Haavanlammi, and the company has
confirmed the materials of construction
in the pilot-demonstration plant. The
process is ready for a first commercialscale
plant.
installed into new facilities. The closedloop
nature of the process (resulting in
recyclable effluent, as opposed to hazardous
waste) results in reductions in water
usage and sludge-disposal costs. Also,
the use of activated carbon rather than
other materials allows for non-hazardous
specifications to be applicable, providing
further cost savings. Currently, LES sees
viable applications for the Enviro-Clean
treatment in the fields of printed circuitboards,
steel and coil coatings, aluminum
windows, high-speed electroplating,
chrome plating and acid-mine drainage.
Future iterations of this technology are
planned that will address the recycling
of wastewater from hydraulic fracturing
(fracking) operations. Also, a similar catalytic
activated-carbon process has been
developed that will target and destroy
cyanide-based compounds.
12 ChemiCal engineering www.Che.Com august 2014
Nickel EW
Nickel
Improved pinch analysis
last month, the national
PinCh-Center of the lucerne
university of applied sciences
and arts (hslu: switzerland;
www.hslu.ch/tevt) introduced
PinCh 2.0, a new version of
its pinch-analysis software,
which is now able to optimize
processes with either multiple
operating cases or batch operation.
" the manufacturing
processes of chemical, pharmaceutical,
food-and-beverage
products often feature differing
operating conditions or discontinuous
production situations.
these processes in particular
exhibit a considerable potential
for improvements in efficiency, "
explains Beat wellig, head of
the PinCh-Center.
Detecting attograms
said to be the first significant innovation
for electron-ionization
(ei) design in decades, the new
high-efficiency ei source, developed
by agilent technologies
inc. (santa Clara, Calif; www.
agilent.com) enables the company's
new 7010 triple Quadrapole
gs/ms system to deliver
attogram (10-18 g) detection
limits. along with lower detection
(Continues on p. 14)
http://www.outo http://www.tec.com http://www.hslu.ch/tevt http://www.agilent.com http://www.Che.Com
Chemical Engineering August 2014

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