Chemical Engineering August 2014 - 18

Newsfront
HCl acid
Production processes
Production of lithium compounds
from brines has usually been seen
as more cost-effective than production
from spodumene. Brines usually
require evaporation in ponds, which
may take more than a year. There
are minerals-processing companies
that claim to have found methods of
eliminating the need for evaporation
and thus reducing the time it takes
to produce lithium compounds from
several months to a few hours.
However, lithium concentrate is
considerably higher in pegmatites
than in brines, making pegmatite
deposits economically viable and
able to compete with brine deposits.
Since hard-rock lithium deposits
are found worldwide, in contrast to
the brine deposits, a large number
of exploration projects for hard-rock
lithium deposits has been initiated
in various parts of the world. Exploiting
local lithium-mineral resources
puts the industry in a stronger
and less dependent position.
Processes for producing lithium
carbonate from lithium-containing
ores typically used thermal
treatment - at a temperature of
about 1,100°C - of the normal,
a-spodumene with a monoclinic
crystal structure, transforming it
into b-spodumene which crystallizes
in the tetragonal system and
which can be solubilized by acid.
The b-spodumene is sulfated in acid
in a kiln, producing water-soluble
lithium sulfate. The lithium sulfate
goes through one or more leaching
tanks. Limestone, lime and sodium
carbonate are added to the product
of the leach to adjust the slurry's
pH, thus precipitating certain impurities
such as iron, aluminum,
magnesium and calcium. The residue
is then separated, leaving a
concentrated solution of lithium
sulfate. The lithium sulfate is then
treated with a concentrated sodium
carbonate solution, thus precipitating
lithium carbonate.
However, those processes are relatively
inefficient in the removal
of impurities remaining in the
pregnant leach solution, and this
is critical when producing batterygrade
lithium carbonate. Also, in
Stage 1
leach
Calcining
furnace
1,050°C
Alpha spodumene
Cooler
Beta
spodumene
Leaching
Alumino
silicate
waste
Figure 1. This patented
process produces battery-grade
lithium carbonate
Battery
grade
Li2CO3
Source: Galaxy Resources
those processes, several byproducts
are wasted.
Several minerals-processing companies
have developed technologies
to address these problems.
One example is Galaxy Resources
Ltd. (Perth, Western Australia; www.
galaxyresources.com.au), which has
developed and patented a process
for producing battery-grade lithium
carbonate. The process (Figure 1)
comprises the following operations:
* Calcining a a-spodumene to produce
b-spodumene
* Sulfating the b-spodumene at elevated
temperature
* Passing the sulfated b-spodumene
through a leach step in which lithium
sulfate is leached in water
* Passing the pregnant leach solution
to a series of impurity removal
steps in which iron, alumina,
silicates and magnesium
are precipitated and removed
* Adding sodium carbonate to the
previous step by which calcium is
precipitated
* The product of the previous step
is passed to an ionßexchange step
in which residual calcium, magnesium
and other remaining multivalent
cations are removed
* Passing the purified product of the
previous step through a lithium
carbonate precipitation step in
which sodium carbonate is added
to produce precipitated lithium
carbonate and a sodium sulfate
mother liquor
* Passing the mother liquor to an
anhydrous sodium sulfate recov18
ChemiCal engineering www.Che.Com august 2014
Dryer
Ferric
alumina
Filters
Al, Fe,
Mn, Mg
ppts
HCl
removal
HCl acid
Battery
grade
LiOH.H2O
Dryer
Washer
Dryer
Evaporator/
crystalizer
LiCH
CO2
Filter
Electrolysis
dilution
Li2CO3
precipitation
ery process, from which a solid sodiumßsulfate
product is obtained
and a portion of the sodium sulfate
mother liquor is also recirculated
to the leach step
Galaxy's process has been used to
produce battery-grade lithium carbonate
at its Jiangsu Lithium Carbonate
Plant in the Yangtze River International
Chemical Industrial Park
of the Zhangjiang Free Trade Zone in
China's Jiangsu Province. The lithium
originates from Galaxy's Mt. Cattlin
mine at Ravensthorpe, Western Australia.
However, last May, Galaxy sold
the Jiangsu plant to Sichuan Tianqi
Lithium Industries, part of Chengdu
Tianqi Group (Chengdu, China; www.
tianqigroup.cn).
Galaxy Resources will now focus
its efforts on the Sal de Vida lithium
brine and potash project in Argentina.
Galaxy's managing director,
Anthony Tse, says the company will
continue to retain significant exposure
to the lithium sector through
the Sal de Vida lithium brine project
with Mt. Cattlin in Western Australia
and James Bay in Quebec.
Last year, Sichuan Tianqi Lithium
Industries purchased Australian
company Talison Lithium Pty Ltd.
(Perth; www.talisonlithium.com),
which produces lithium concentrate
at its project located in the town of
Greenbushes. The Chengdu Group
now controls about a third of global
lithium supply. At full capacity, the
Jiangsu plant will produce 17,000
metric tons (m.t.) of battery-grade
lithium carbonate per year.
solution
Electrolysis
Ca
ppts
Na. K
ppts
IX Process
Ball
milling
Stage 2
leach
Thickening
Fractional
crystalizer
.
Heating
300°C
LiOH
slurry
Li2CO3
slurry
LiCl
solution
http://galaxyresources.com.au http://www.tianqigroup.cn http://www.talisonlithium.com http://www.Che.Com
Chemical Engineering August 2014

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