In the future, will we call it
TiO2 or tai bai fen [TiO2 in
Chinese]?
That was the question posed by
David McCoy, managing consultant and director of mineral sands
consultancy TZMI, on the last day of the annual TiO2
conference in Hong Kong
And the point McCoy was making to
delegates, following two days of papers, was that China is the
future of TiO2, irrespective of its
current downturn.
Chinese demand for TiO2
is projected to rise to 35% of the total global market by 2020,
from 25% today. Demand from the emerging economies will remain
consistent at around 33%, but demand from the advanced
economies is projected to fall to 33% from 40% by 2020.


Sulphate route not going away
Chinese sulphate is not going
away as a process, McCoy said, adding that, while the
global market is now probably equally divided between chloride
and sulphate, the latter will begin to rise and by 2020 he
expects the split to be 54% sulphate 46% chloride.
This projected rise to 2020 is not
simply a beginning to Chinas growth, but rather a
continuance, as the countrys demand for TiO2
has risen by almost 10% since 2005 to 25% of the world market
today.
The countrys production has
also rocketed. From being practically non-existent as recently
as 1990, it rose to be the worlds second-largest
producer, neck-and-neck with the US by 2010, and projected to
become the world number one by a substantial margin in the
future.
This is being helped by consumers
outside of China increasingly opting for Chinese sulphate grade
TiO2, McCoy added.
We are sure that some people
have made the decision to go with a different source - still
TiO2, just a different area of the world, he
said.
Now China has switched to
lower-grade, and therefore lower-priced, feedstock mixes,
pigment end-users are unlikely to switch back, which will
further boost demand for Chinese sulphate products outside of
the country.
Chinese supply leaving the
country has risen, while internal demand has dropped - it is a
net exporter now, he added.
The majority of Chinese
exports go to countries around China - that is the growth
area of the world, he said.
An estimated 37% of production this
year has gone to surrounding emerging economies in Asia
Pacific, but a high proportion is still going to more
established economies, with 13% going to western Europe and 11%
going to North America.

The possibility of Chinese chloride production
Official Chinese government policy
has seen an increasing number of producers focusing on chloride
production. This edict has even gone as far as to refuse
sulphate-route companies permission to carry out IPOs.
The countrys first, and
currently only, plant was Jinzhou, which entered production in
the early 1990s and produces approximately 60,000 tpa with a
rumoured ramp up to 100,000 tpa expected.
However, questions remain over the
quality of the product.
Yunnan Xinli Nonferrous Metals Co.
Ltd has also claimed to have a chloride process bought from a
European consultancy business but the authenticity of the claim
has been questioned by its peers.
Of the projects in the pipeline,
the most promising are in Henan province. Henan Billions
Chemicals Co Ltd recently completed a deal with German
management consultancy Ti-Cons for processing technology as
well as having already completed a deal with paint producer PPG
for relevant technology and development aid.
The [...] agreement between
Henan Billions and Ti-Cons is for the delivering of the
complete know-how for the erection and operation of a plant for
the production of 100,000 tpa of TiO2 using the
chloride route, Christian Weiland of Ti-Cons, said.
Ti-Cons specialises in
TiO2 process technology, especially in bringing
chloride-route technology online.
Lucha Xiangmao, also in Henan,
announced that it will construct a 60,000 tpa chloride
plant.
Pangang Group and CYMG have also
had projects under construction for some time, but the former
has been hampered by accusations of trade-secret theft from
DuPont.
DuPonts Dongyings
project has reportedly been shelved, but may resurface at some
time, McCoy said.
Chloride-route technology was
invented in the US and is utilised mostly by major western
producers such as DuPont (US), Kronos (US), Cristal Global
(Saudi Arabia), Huntsman (UK) and Tronox (US).
Despite this activity, two major
obstacles stand in the way of chloride, TZMI said.
The feedstock in the country
is not suited to the chloride process, said McCoy, adding
that the majority of internal feedstock produced is either
ilmenite or chloride grade slag, both of which are suited to
the sulphate process.
The second is the issue of
intellectual property, as the chloride process is extremely
complicated to apply and most processes are controlled by the
leading producers.

TiO2 - the facts
Titanium dioxide, better known by
its chemical formula TiO2, is a simple inorganic
compound used as a white pigment.
It has a very high refractive index
of 2.7, which compares with values of only 2.0 and 1.6 for zinc
oxide and china clay respectively. This high refractive index
gives the potential for producing much greater opacity or
hiding power, making TiO2 a much better pigment.
It can be produced in either an
anatase or rutile crystalline structure. Rutile is more stable
under high heats than anatase TiO2. At over 700°C the structure of anatase crystals
changes to that of rutile.
The rutile crystalline structure is
also more compact which gives it a higher specific gravity
(4.23-4.25 v 3.8-4.0) and a higher measurement on the Mohs
Hardness scale (6-7 v 5.5-6). Rutile also has a higher
refractive index than anatase (2.76 v 2.55).

Feedstock
TiO2 is not found in
nature, but must be made from the feedstock minerals rutile,
ilmenite, and leucoxene. It can also be made from the synthetic
feedstocks, synthetic rutile and titanium slag, which are
themselves made from natural feedstocks.
Rutile is the best and most
expensive of the natural feedstocks whereas ilmenite can only
be used in the sulphate process or upgraded into a synthetic
feedstock. While rutile is sourced only from mineral sand
deposit, ilmenite can come from either hard rock or mineral
sand deposits.
Synthetic rutile is produced by
reducing the iron oxide in ilmenite to metallic iron using
carbon monoxide, followed by reoxidation and separation from
the TiO2 rich fraction (Becher process) or leaching
with hydrochloric acid (Benelite process).
Slag feedstocks are produced by the
smelting of ilmenite with coal at high temperature. The process
is adjusted to produce the different particle size requirements
for sulphate or chloride use.
Leucoxene tends to have a high
titanium percentage (70%-80%), but is exceedingly rare.

The industry
The titanium dioxide feedstock
supply is dominated by Australia and South Africa. Pigment
production, however, is centred on several major companies in
the US and Europe.
China also has a large centre of
production, but the majority is sulphate-route products. Only
the Jinzhou plant, which was recently expanded to 60,000 tpa
and is now majority owned by the Citic Group, produces using
the chloride-route.
Several more may come on stream by
2015. The Pangang Group has claimed to be developing a
100,000-150,000 tpa chloride-route plant, but is in a dispute
with the US government over the alleged theft of DuPont trade
secrets.
Henan Billions is also developing
chloride technology and has partnered with leading paint
producer PPG Industries, which produced chloride-route
TiO2 itself in the 1970s, to develop a 100,000 tpa
chloride-route plant.
The processes
Titanium dioxide (TiO2)
is mainly refined using one of two processes. The newest is a
process that uses hydrochloric acid, but the technology is not
widely available and supply is restricted to several large
companies.
There are other companies that have
chloride technology, but the most modern technology is highly
patented and protected. ISK Japan also produces chloride-route
TiO2.
The other process, which is more
widely available, involves the use of sulphuric acid and is
used throughout the US, Europe and China.
Major producers include Rockwood
Specialties and its European segment Sachtleben, and Cinkarna
Celje, Crimea Titan, Precheza AS, and Zaklady Chemiczne Police
SA.
As of 2012, Rockwood is attempting
to divest its TiO2 assets in order to focus on
lithium.
Other processes do exist, such as
Argex Minings CTL process, which creates TiO2
straight from ilmenite, but the chloride- and sulphate-route
processes account for nearly all of the worlds
production.
Advantages of the chloride
process
The chloride process has several
key advantages over the more widely available sulphate process.
The first is that it gives a better quality of pigment that has
better hiding powers and tinting strength and gives better
coverage when used.
The chloride process is also much
more environmentally friendly. However, the environmental
impact of TiO2 production is mostly a factor of the
raw materials used, the effluent treatment processes and the
degree of by-product development a particular plant has.
A key difference between the
processes is the choice of feedstocks that can be used.
Ilmenite, the cheapest of the feedstocks, is rarely used by
chloride-route producers because the low TiO2
content leads to high chlorine losses and high volumes of waste
products.
Instead, chloride-route producers
prefer to use natural rutile, synthetic rutile and chloride
grade titanium slag. The most expensive of these, rutile, has
the highest TiO2 content so gives the lowest waste
volumes, followed by synthetic rutile and chloride-grade
slag.
The sulphate process, on the other
hand, thrives on the cheaper feedstocks as rutile-based
compounds cannot be digested in sulphuric acid. The actual
feedstock used by the plant, depending on whether it is
sulphate-grade slag or ilmenite, will be determined by overall
costs and environmental regulations (especially regarding waste
discharge) and usually decided at the plant design stage.
How the chloride process
works
The chloride process chemistry uses
heat, chlorine gas and titanium feedstocks to create a bright,
white TiO2.
The overall chemistry of this
process can be represented as:
TiO2 + C +
2Cl2 = TiCl4 + CO +CO2
TiCl4 +O2 =
TiO2 + 2Cl2
Chlorination is carried out at a
temperature of between 800° and
1200° in a fluidised bed reactor in
the presence of coke. The resulting gas stream contains
titanium tetrachloride (TiCl4), oxides of carbon
(CO, CO2) and all the impurity metals from the
feedstock in the form of metal chlorides.
The gas stream is cooled, which
allows the other metal chlorides to separate out as solids, and
the TiCl4 goes onto the next stage where it is
further cooled and condensed as a liquid and then fed to a
high-temperature oxidation reactor.
Here, it is reacted with oxygen in
a plasma reactor or toluene burner to reform into titanium
dioxide and the chlorine is released and filtered off back to
the beginning of the process. The only chlorine consumed is
that which reacts with impurities.
This TiO2 is then
processed using a range of chemical surface treatments, milling
and drying operations to give a range of products, such as
dispersion and durability, which make it more suitable for its
particular end-use applications.
This finishing stage of
the process can include chemical surface modification,
filtration washing and drying, grinding, slurry makeup and
additives to give it other properties.
The sulphate
process
The sulphate process is a slightly
more complicated process in terms of the number of stages
involved, but it produces either rutile or anatase
TiO2.
If ilmenite is used, a reduction
step is required in which iron is added to convert any ferric
iron to the ferrous form to aid separation later in the
process.
The overall chemistry of the
process can be represented as:-
FeTiO3 +
2H2SO4 = TiOSO4 +
FeSO4 + H2O
TiOSO4 + H2O
= TiO2n.H2O +
H2SO4
TiO2n.H2O =
TiO2 = n.H2O
The feedstock is first digested in
strong sulphuric acid, which converts the titanium components
into titanyl sulphate (TiOSO4) and the iron into
sulphates (FeSO4). This creates a liquor that the
rest of the process will work with.
This is followed by a clarification
step to remove any undigested material from the liquor. For an
ilmenite process, crystallisation typically follows, which
separates out co-product ferrous sulphate heptahydrate
(copperas), although it is also possible to extract copperas
later in the process.
The liquor passes forward to a
hydrolysis stage in which the oxysulphate is reacted with water
to produce a hydrated titanium dioxide product and releases
sulphuric acid. The hydrated TiO2 passes forward to
a rotary kiln, where it is calcined to produce the anhydrous
titanium dioxide product.
The TiO2 product then
undergoes mostly the same finishing as product produced by the
chloride process, that is chemical surface modification,
filtration washing and drying, grinding, slurry makeup and
additives to give it other properties.
The acid that is released at
hydrolysis is not strong enough to be recycled and used
directly at the digestion stage earlier in the process, so it
must be either concentrated, to make usable acid, or
neutralised to produce gypsum.
Making anatase
crystals
To produce the anatase form of the
titanium dioxide, a small portion of the liquor is neutralised
with an alkali to produce anatase microcrystals. These
microcrystals are then introduced into the main liquor, which
is then hydrolysed under controlled conditions to produce
anatase crystals.
To produce the rutile form of the
titanium dioxide, a small portion of the liquor is neutralised
in the presence of hydrochloric acid (or another monohydric
acid), which is then reintroduced when the main liquor is
hydrolysed.
The market
The consensus at this years TZMI conference was that the
skies remain cloudy for both zircon and titanium dioxide
pigment (TiO2) markets.
The boom of 2011 that led to such a
positive conference last year has now faded.
What a difference 12 months
makes, Philip Murphy, TZMI managing director, told the
conference.
Last year was a year of two halves
for both the zircon and TiO2 industries, he added,
and this year seems to be following a similar pattern, with a
global slowdown showing clearly in the second half of 2012.
The main cause of this has been
destocking by end-users and reciprocal drops in plant
utilisation rates.
Most zircon markets, in particular,
are remaining weak and a short-term turn around seems unlikely,
he said.
The short-term future appears
bleak.
We see surpluses [in supply]
for the next couple of years [...] if supply reacts to market
weakness, we could see further cutbacks [in production],
he said.
Demand will also weaken and 2012 is
likely to show a decrease of 9%, he added.
This will hit zircon especially,
where he believes there are inventory excesses of 200
days - maybe even 250 - [...] and that will take some
time to unwind.
Trading conditions [for
zircon] are going to remain tough for a while, he
said.
For TiO2, on the other
hand, Murphy could see improvement as early as the second half
of 2013.
A real return to growth we
only expect in the second half, said Murphy.
The current downturn could also
affect new projects as investment capital dries up, which will
delay their production schedules.
The grey clouds will not disappear anytime soon and
there are a couple of darker ones in the background,
Murphy added.