It’s complicated: How mineral scarcity and human ingenuity shape the world of TiO2 feedstocks

By Cameron Perks
Published: Monday, 22 October 2018

Amid growing concern about the supply of titanium dioxide feedstocks, Fastmarkets examines the scarcity of these minerals and how processors are adapting to changes in availability.

A growing global population is boosting demand for materials for building and technology, sectors in which mineral sands play a key role - predominantly through ceramics for zirconium minerals and pigments for titanium minerals.

Emerging countries - where economic growth tends to outpace global gross domestic product (GDP) - present the biggest opportunity for growth in titanium and zirconium demand.

And given very low recycling rates - zero, in the case of TiO2 pigment - long-term demand for companies looking to produce mineral sands looks very healthy.

But the depletion of easy-to-access resources to meet that demand raises questions about where and when the next Eneabba, Jacinth Ambrosia or Richards Bay might be found.

The finite nature of mineral resources has influenced the titanium pigment industry’s development. For example, while the preferred feedstock of chloride pigment producers is natural rutile, they have in the past made various upgraded products such as titania slag and synthetic rutile from ilmenite when rutile sources were scare.

The perceived shortage in some mineral sand minerals, particularly rutile, has driven innovation in pigment processing technology, particularly in chloride pigment. This innovation is likely to continue for as long as rutile supply looks tight.

One element of this innovation is the blending of feedstocks. Some producers can use a combination of feedstocks (with variable TiO2 and other elements) in their processes; others are able to use a lower-grade titanium feedstock. Only Chemours uses ilmenite with TiO2 content of more than 55% TiO2 in its chloride process.

Currently, natural rutile, synthetic rutile, upgraded and coarse slag (>85% TiO2) are suitable for chloride-route pigment production, which is more environmentally friendly and produces much less waste.

Process1  

A balance must be achieved between a perceived shortage in high-grade titanium feedstocks and the need to preserve the environment. This is evident in China, where chloride pigment production is growing, albeit very slowly.

The growth rate of chloride and sulfate pigment production was a hot topic at the Australian Informa 2018 Mineral Sands conference earlier this year in Perth, Western Australia, for example.

Doubts were cast as long ago as 2009 about the pace at which this change would take place, particularly in China. Since then, though, China has managed to build a combined 250,000 tonnes per year of chloride pigment capacity between Lomon Billions, Citic Titanium Industry, Yunnan Xinli Non-Ferrous Metals (although operations there are reported to be suspended), Luohe Xingmao Titanium (likewise), and Pangang Group, which has a trial production line in operation.

Capacity for chloride pigment elsewhere is set to rise, particularly if the much-anticipated Tronox-Cristal merger takes place. Cristal built its Saudi Arabian Yanbu chloride pigment production facility in 1989 only for it to have continually suffered from low operating rates ever since.

Similarly, the company has not yet reached the production stage with its Jazan titanium slagger, despite millions of dollars of investment since 2015 in the hope of producing chloride slag.

If Tronox is able to bring the Yanbu works to full operating capacity, and bring Jazan online with its in-house expertise following the merger, it will require ilmenite as a feedstock for Jazan and perhaps even rutile to help feed Yanbu.

Tronox operates the Cooljarloo mine in Australia, as well as the Namakwa and KZN mines in South Africa. Presumably, production at these mines will be enough to feed the Cristal smelter and pigment operations, although these mines will ultimately run down and new mines will have to be found to replace them.

Despite some setbacks, then, it seems that overall chloride route production is favored, particularly thanks to its environmental sustainability. But what can current and future producers do about resource scarcity?

The answer is: not much in the short term. While Chemours has the greatest flexibility in terms of switching feedstocks, not all pigment producers have the same ability.

Factors such as impurities, size distribution, density and even the shape of slag, rutile, synthetic rutile and ilmenite make it hard for producers to switch from rutile to a chloride ilmenite, for example, or even from a sulfate ilmenite to a sulfate slag, since these can affect the performance of the chlorination circuit.

The choice of feedstock depends on factors such as the process plant design; the economics of the process due to differences in price of feedstocks and various impurities; any loss in production due to process and equipment downtime in testing a new feedstock; the cost of waste treatment and solid waste disposal; and quality of the TiO2 pigment product.

Switching feedstocks has physical, chemical and economic implications for users.

Many market participants have tipped Kronos, a major global pigment producer, to be affected most by the dwindling availability of high-grade titanium feedstock. Because its Belgian plant requires a predominantly rutile feedstock, it will be forced to pay a higher price to its suppliers, one market source said.

One short-term solution will come from Iluka Resources, which is planning to bring online in the first half of 2019 around about 200,000 tpy of synthetic rutile production, fed by around 370,000 tpy of chloride ilmenite from Cataby at its SR2 kiln.

While this will provide some relief, it will not help all pigment producers and cannot help some other parts of the sector such as welding.

Process2  
Iluka is looking to complete a DFS into the expansion
of Jacinth Ambrosia, which would result in a ~30%
increase in ore throughput to offset declining ore grades.
Iluka Resources 

In the long term

There are several possible long-term solutions for the perceived shortage of high grade titanium feedstocks.

For example, global chloride feedstock capacity could increase via the discovery and development of some large high-quality rutile or ilmenite deposits, as well as the possibility of adding some new slag or synthetic rutile capacity.

For ilmenite, this means deposits that can either be used directly in pigment production or that can be upgraded. For ilmenite used directly in pigment production, the chemistry for sulfate or chloride route production should be considered; sulfate-suitable ilmenite tends to more primary in nature and has more FeO and fewer Fe2O3 phases in the iron content, making it more soluble in sulfuric acid for the sulfate pigment process.

Chloride grade ilmenite, though, is more tertiary in nature so it contains more Fe2O3 and minimal FeO, which makes it easier to chlorinate in a chloride route plant.

Where ilmenite undergoes upgrading via slag production, a specific type of ilmenite is also required. This is because, just as in direct use, there are elements such as chrome that carry across and make the slag unsuitable for pigment production. Chrome, for example, will typically affect sulfate and chloride slag production methods.

During the slagging process, the slag bullets or pigs that are produced are smelted, crushed and screened. The resulting coarse particles are chloride grade while the fine particles are sulfate grade. While there tends to be some quality segregation between the particle sizes, they are usually close for titanium content and other elements; both grades are normally made at the same time, from the same ilmenite (regardless of whether that be a sulfate or chloride grade ilmenite).

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In fact, sulfate ilmenite is considered the best feedstock for slag production and chloride grade ilmenite for Becher process synthetic rutile production, which is again due to the FeO/Fe2O3 ratio. High FeO is best for pig iron formation - it can be tapped off separately in the slag furnace to leave the titanium slag. FeO does not reduce with coal in a synthetic rutile kiln, however, whereas the Fe2O3 reacting with CO from the coal to leave metallic iron on the ilmenite grains and CO2 is relatively rapid in comparison.

So although not every ilmenite is suitable, it is the most widespread titanium mineral on earth, which gives explorers a very good chance of finding something useable.

The vast majority of the world’s ilmenite resources are found in Australia, South Africa, India, Brazil, Madagascar and the United States, in mineral sand deposits but also in primary hard rock deposits such as Tellnes in Norway and Allard Lake in Quebec, Canada.

In 2017, the United States Geological Survey (USGS) estimated world ilmenite reserves at 870 million tonnes, with production amounting to 6.2 million tonnes in that same year. This includes the ilmenite produced in Canada and South Africa, which is primarily used in the production of slag.

An alternative to finding and using ilmenite and, in some cases, to upgrading it is to find naturally occurring rutile, which unlike rutile does not need to be upgraded. But in contrast to ilmenite, world reserves of rutile are concentrated in Australia, Kenya and South Africa. In 2017, the USGS estimated global rutile production at 900,000 tonnes from a global reserve of 62 million tonnes.

Other titanium feedstock-using industries, such as welding, add another layer of complication. The welding industry cannot use synthetic rutile but only natural rutile (TiO2 of 94% purity and better is preferred) or the higher grades of leucoxene (88% and over), slag and sometimes reduced ilmenite.

It is not only the chloride pigment industry that requires more rutile. But what if none is forthcoming?

There are multiple ways in which plentiful supply of ilmenite can be upgraded into chloride pigment production as well as sulfate pigment production, even if the volume of suitable ilmenite is unknown.

And there is a very good case for human ingenuity, particularly for the welding industry, in that it will find ways to work with the deposits that are available.

Slag producers

Rio Tinto produces titanium slag at Sorel in Canada as well as at Richards Bay Minerals in South Africa. TiZir produces titanium slag at Tyssedal in Norway and Lomon Billions at its Chinese operations. Richards Bay, Sorel and TiZir produce slag suitable for both the chloride- and sulfate-processing routes.

Tronox produces titanium slag at its operations in South Africa using its own proprietary technology. It is suitable for both chloride and sulfate processing.

Synthetic rutile producers

Iluka and Tronox produce most of the world’s synthetic rutile at their plants in Western Australia (Tronox is also a large consumer of synthetic rutile in its pigment production process). Other plants in India and Malaysia use a different processing technique.

Maoming Ubridge Group is reported to be working on a synthetic rutile operation in China. It has 100% of Strandline Resources’ future ilmenite production under offtake agreement, presumably as feedstock for this process.