Manufacturers’ Monthly Material of The Month Part 4: Titanium

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Tapping Australia’s titanium ore resources and turning them into the valuable light metal has been something we’ve wanted to do for a long time. Are we any closer to making more from our ore? Brent Balinski reports.

Tricky, expensive to make, but very useful

It’s not new and is fairly abundant in nature, but titanium’s use is limited by how tough it is to isolate.

However, things might be improved on soon, with efforts in processing in Australia and elsewhere showing promise.

Titanium, the fourth most-common structural metal on earth, was first identified in 1791 by Reverend William Gregor, a chemist from Cornwell.

It was until 1910 when titanium was first synthesised, by MA Hunter. As with many other inventions, it came about as the result of research at the General Electric company in the US.

Hunter used titanium tetrachloride (TiCl4, sometimes referred to as “tickle”), heat and sodium under a vacuum to create Titanium.

The method was bested by the multi-step Kroll Process, currently in its ninth decade and still used to create almost all the world’s titanium.

Kroll involves creating TiCl4 by heating titanium dioxide to about 1,000 degrees Celsius and reacting it with chlorine. The “tickle” is then covered with argon and reacted with magnesium at about 850 degrees Celsius.

This takes place in batches in stainless steel retorts, which react with titanium (about 20 per cent of the sponge produced becomes ferro titanium and has to be removed manually).

The sponge is then removed and melted into ingots.

The overall process is labour- and energy-intensive, but has not been replaced.

The time and effort will be paid for by those wanted titanium, because – though expensive – it is the only material that will work in certain applications. The reasons for this include its excellent resistance to corrosion, high strength to weight ratio, and ability to withstand high temperatures – its melting point is 1,670 degrees Celsius.

Its compatibility with composites – increasingly used to reduce the weight of planes – also means that aerospace couldn’t do without it.

“The combination has made it a critical material,” Professor Xinhua Wu from Monash University told Manufacturers’ Monthly.  

“You can’t do without it, especially for composite aircraft… Between composite you must have titanium to hold them together; Titanium doesn’t corrode, and if you put aluminium between them it will corrode.

“That’s why the use of composites has also increased the usage of titanium. [Also] the front part of the engine is all titanium almost, because it’s light and at high temperature nothing else can do the job.”

Titanium is about half the weight of steel, yet as strong, with a density of only 4.5 grams per cubic centimetre.

Characteristics, including those above, also mean it is highly useful in applications including marine engines and components, the energy industry, and in biomedical implants (titanium is also biocompatible and remains inert in bodily fluids).

A wealth of ore

Australia does not produce titanium as a metal in any significant quantities, though is fortunate enough to have world-ranking deposits of ore.

According to the Australian Mines Atlas, Australia has a wealth of titanium ore in mineral sands concentrated along the east and west coasts. These represent the world’s biggest economically demonstrated resources of ilmenite (29 per cent of the world’s stores) and rutile (44 per cent).

Worldwide, about 95 per cent of the titanium dioxide processed stays as titanium dioxide, which is a useful, non-toxic pigment, used for purposes including paint, in self-cleaning windows and as food colouring (additive E171).

Australia processes titanium dioxide, though some will tell you there’s a huge value-add opportunity being lost through our lack of a titanium metal processing industry.

To illustrate, according to John Barnes, Titanium Theme Leader at the CSIRO, a kilogram of mineral sand is worth about 10 cents, a kilogram of the titanium metal $50, and a finished part for aerospace thousands of dollars.

How are we making titanium cheaper here?

Using the same chemistry as Kroll, but with much less energy (and several other improvements) the CSIRO has been developing its TiRO method of continuous titanium production for several years.

TiCl4 is continuously reduced in a “fluidised bed”, where particles act like they’re suspended in a liquid while floating in argon gas. This means the titanium does not become contaminated as it would through contact with the sides of a steel tank.

According to the CSIRO, the benefits over Kroll include being continuous (rather than batch), compatible with just-in-time manufacturing processes, full automation, ease of setting up, and a much lower environmental impact.

“With Kroll you’d be doing a pretty laborious approach to get it from titanium tetrachloride into a solid, pure form; then you’d have to melt it, then you’d have to alloy it, which would include melting it again,” Barnes told Manufacturers’ Monthly.

“The TiRO process doesn’t involve melting, ever. It’s all in a solid state. So we believe that it’ll be quite competitive against product coming out of a conventional process.”

TiRO could generate 200 grams of titanium powder per hour at its proof of concept stage, but can now generate powder at over 2.5 kilograms in the same period.

Since 2008 Coogee Chemical has been partnered with the science organisation on TiRO, and Barnes pointed out that CSIRO is now taking a back seat.

Coogee is currently running a pilot facility at Laverton, and – along with methanol – lists TiRO among its “emerging opportunity” plans.

Tim Martin, the company’s managing director – and who will take over as executive chairman in July this yearhas described TiRO as a “process which could be a game changer, and that is something that we’re very much focused on, and has potential to take this company to the next level.”

Coogee were approached for comment but declined to discuss their plans for developing TiRO.

Among the major successes since joining CSIRO in 2011, Barnes lists effectively licensing both of the organisation’s titanium producing processes, TiRO and the alloys process.

The Cambridge Method

About a year ago, mineral sands miner Iluka Resources got people talking when it took out an 18.3 per cent interest in English-based, venture capital-backed company Metalysis, for which it paid $22 million.

Metalysis was established in 2001 to commercialise a novel, electrolysis-based titanium processing method developed in 1997 by University of Cambridge’s Material Science and Metallurgy Department.

Sometimes referred to as “The Cambridge Process” or “FFC Cambridge Process”, the method has been seen as potentially disruptive for a long time. Iluka has been watching Metalysis for “about seven years”, Robert Porter, Iluka’s General Manager, Investor Relations, told Manufacturers’ Monthly.

“The main attraction for Iluka is as a supplier of high-grade titanium dioxide feedstocks, is if this technology can be commercialised it will enable the transformation of titanium dioxide feedstocks, such as rutile, synthetic rutile, into titanium powder, which can then be used in a range of metal applications,” he said.

Metalysis’s technology can be used to extract metals using “molten salt chemistry” (see below). It is suitable for extracting a range of metals, such as tantalum, but the focus is on titanium.

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According to the company, it is able to produce metal powder about 75 per cent more cheaply than the current prices of about $US 200-400, directly from rutile.

“Metalysis’s technology is unique because it uses electrolysis, which means the conversion of feedstock to metal powder is a one-step, solid state process that does not require the use of harmful chemicals,” Kartik Rao, Metalysis’s director of business development, explained to Manufacturers’ Monthly in an email.

“The use of the inexpensive feedstock for titanium manufacture will dramatically reduce the cost of titanium production, allowing its increased use.”

Metalysis’s method is able to customise feedstock according to the output, said Rao, making the powder produced suitable for different applications.  

Rao’s company is producing small amounts of titanium for industrial customers. They are particularly interested in the growing demand for metal 3D printing, with the directly produced, customisable powder produced able to make additive manufacturing a viable option for new markets, said Rao.

The quality of the powder is still a work in progress, which continues to be developed to meet the changing demands of those using it.

“Metalysis is working closely with industrial and academic partners to identify new parameters to check and control,” said Rao.

“With specific reference to purity, the Metalysis process is capable of using high purity, pigment grade titanium dioxide that allows high purity metal powder to be produced, if required.”

Useful, but not without its limitations

According to Wu, purity is still a concern with the Metalysis process for applications such as aerospace and biomedical.

“There’s not much they can do about it – it’s nature, that’s how nature works,” she said of issues around the difficulty in completely removing contaminants such as calcium chloride from powders.

“This powder may gradually get into the market, maybe in another 10 years when we are able to solve some of the problems to get into the market.”

According to Barnes, the “at least half a dozen” different processes for creating titanium each offer something different and are thus beneficial to those working with the metal.

“If you look at the Metalysis one, it’s quite a different technology to the one we have to offer, and it would produce a different sort of chemistry than we would produce,” he offered.

Having all of these emerging, non-Kroll methods moving up the technology readiness level was a good thing. They could possibly offer alternatives to those looking at lightweighting metal products or seeking heat or corrosion resistance.

“It’s good for industry because it allows them a different approach maybe to what they’ve been taking, with Duplex stainless steel, for example,” he said.

Potential for Australia

Professor Wu, who has an extensive background in aerospace engineering, heads Monash’s Centre for Advanced Manufacturing and the lengthily-named Australian Research Council Hub for Transforming Australia’s Manufacturing Industry through High Value Additive Manufacturing.

Launched in November last year and located across the road from Barnes’s Lab 22 in Clayton, the hub concerns metal additive manufacturing, including titanium, applied to industries such as aerospace and biomedical implants.

“I think that those are the two areas where the high value is obvious, and also drive technology development,” she said.

The first three projects identified at the hub were around aerospace and a generator engine, as well as a medical instruments.

Biomedical purposes are, it’s been frequently noted, an area where titanium additive manufacturing could hold great potential in Australia.

The biocompatibility of titanium coupled with the freedom of design and ease of customisation offered by 3D printing mean that it’s been a winner in the early days of metal additive manufacturing.

For example, last year it was estimated that some 90,000 titanium acetabular cups had been made so far.

Dental copings were another popular application.

One novel example from October last year was a world-first titanium heelbone implant for a cancer sufferer, which saved the man’s leg.

A collaboration involving the patient’s blessing, the suggestion of St Vincent’s Hospital’s Peter Choong, the design expertise of Anatomics, and support from CSIRO’s Arcam EBM machine, it was an example of what’s possible.

“It was an A plus B plus C plus D scenario,” offered Barnes.

Was it an example of the kind of advanced manufacturing Australia could do well?

Yes, believes the titanium expert.

“I think in general the technology of 3D printing is something that’s ideally suited to a country like Australia, because it’s a great equaliser in terms of if you have a high labour rate, it tends to be very complimentary to that, because it doesn’t require a huge amount of touch labour to make it work,” explained Barnes.

“We run a machine overnight, for example.”

“So it’s a way to improve your productivity greatly. But it still is not just something you can plop down anywhere and it’s going to get used correctly, and still requires a fair degree of education and sophistication around being knowledgeable around how to manufacture things.

Titanium printing-related enquiries to the CSIRO from biomedical companies had been frequent, he added, and it’s sort of a matter of waiting for the right company to come along and take advantage of the technology.

“They’re fairly well versed in the benefits of 3D printing, and this was just kind of a great example of how all this could come together and provide somebody with a unique service,” he added.

“So there’s a lot that goes into getting that stuff certified with the TGA and the FDA out there, but there are several companies that know how to do that out here. It’s a very exciting market for Australian companies to be in.”

The desire for cheap titanium was an old problem, and there were perhaps better places Australia could be focussing its energy.

“We have to basically pull it, pull it into market and develop it by creating manufacturing activity first, so we buy the good powder first, we can buy that everywhere in the world, buy this material first to keep the product going into the market globally, not only in Australia,” she said.

“Then naturally the market will demand that cheaper powder and then they can develop it.”

Australia had great raw material reserves, she said, but the reason it had never developed a titanium industry is because there was no internal supply chain to create enough demand.

Without this, there’d be nothing to serve, even if Australia was able to develop a cheap method for creating the metal.

Her comments were echoed elsewhere by Bruce Ramsay, director of Lovitt Technologies, who told Fairfax that, “It's not worth anyone setting up locally when there's such a tiny market.”

But the quest for cheaper titanium continues. Novel methods of production might change the demand for and use of the metal, if it can just be made more affordable.

Especially for those using it for 3D printing, says Metalysis.

“This technology heralds a new era in additive layer manufacture, which will see greater use of titanium in components across the automotive, aerospace and defence industries,” said Rao.

 

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Story images (in order):

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Dan Christlansen

Metalysis

CSIRO