Dr Colin Nexhip, chemical engineer

Chemical engineer

Dr Colin Nexhip received a PhD in chemical engineering from the University of Melbourne in 1998. His research was on the physical chemistry of foaming in molten slag systems, an energy efficient phenomenon used in iron- and steel-making. While still a student he was invited to present his work to the Royal Society of London and was awarded a CSIRO Innovation Award for the design of a high temperature laser spectrometer, used for measuring the thickness of molten oxide bubble films. In 1999, he was awarded a Victoria Fellowship, enabling him to travel overseas to 'benchmark' his research against other institutions. As a senior research scientist/engineer at CSIRO Minerals, he works on a number of pyrometallurgy projects, including molten oxide chemistry, high temperature physical chemistry and how to improve phase mixing and separation of molten liquids. In 2001 he was a visiting scientist at the German Aerospace Research Centre. There he conducted ground-based preparatory experiments to measure the high temperature properties of molten metal alloys in different gravity settings.

Teachers' notes to accompany this transcript.
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Interviewed by Ms Marian Heard in 2001.

Contents


Family interests in science

Colin, to begin your story: where and when were you born?

I was born in Kyabram, Victoria – a very small town of about 5000 people – in 1969. I am probably one of the last remaining '60s people among my colleagues. I have an older brother by three years, Kevin, and a younger sister by three years, Narelle, who was born on my birthday.

Neither of your parents has a professional background. What early influences led you into science?

My parents were quite supportive of the sciences. My mother, in particular, has always been very interested in maths. She had to leave school at year 10, just for cultural reasons – it was the thing to do at that time – but she was dux of the school and in more modern times she probably would have been able to progress. So she looks favourably upon the idea of my brother (who is also a scientist) and me pursuing that line. Also, my mother's brother has a Masters degree, and he helped greatly by describing the sort of a life that a scientist would lead.

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Well combined: a teaching degree, a science project and a stimulating mentor

For most of your school years you had other interests besides science, and we can talk about those later. But you chose your year 11 and 12 subjects with the specific intention of going into science.

Yes. I guess you have to make choices very early. Once you're around year 9 or 10 you have to start thinking about what career you want, so you know what subjects to choose for the next two years. I started thinking early in high school that I'd love to get into science, maybe as a medical doctor or a vet, something like that.

You went on to the University of Melbourne. What did you study there?

I studied for a Bachelor of Education, as I wanted to be a teacher as well as wanting to be a scientist. Teaching is also within my mother's side – her brother lectures at university, having started off as a high school teacher, so we were able to talk a lot about teaching. I thought it would combine well with science, and I wanted to get my teaching degree in case I ever wanted to go back to it. But I certainly wanted to pursue science as well.

Probably my most important influence toward science was that during fourth-year Education I was able to do a project at the CSIRO, in what was then the Division of Mineral Products, in Melbourne. It was practically one day a week, on a project related to electroplating. Being able to work there, with a scientist called Dr Joy Bear, was very stimulating. Joy was by then one of the most senior scientists in CSIRO, after starting her career as a lab technician in the '40s. I was able to draw on her guidance, and she was my mentor and helped me appreciate how I might use the experience I got at CSIRO to pursue the scientific career further, for example by enrolling in an Honours degree, perhaps in chemistry.

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Superconductors in a precedent-setting Honours project

So although you started out doing an Education degree, your Honours was actually in Science, was it?

Yes. I managed to finish my BEd, so at least I had that to say I could go and teach. But Bachelor of Science with Honours was probably the next stepping-stone to, say, doing a PhD.

The Honours year was fantastic, very successful. I was able to work on superconductors, which in the early '90s was a hot topic (as it still is today), in a project of the Chemistry Department and the Physics Department. I gather that such a joint project set a precedent at the time, and it was nice to be able to be the glue for that. I ended up spending about 50 per cent of my time at each department, and we discovered a new superconducting compound, tested it and published it in an international journal.

CSIRO came back into my life during that time, as it did again later. For part of the Honours project I worked at the Materials Science and Technology Division, in Clayton, Melbourne, where I was able to characterise these ceramic superconductors. I was using techniques like electron diffraction which tell us a lot about the crystal structure, which is important to making the compounds superconduct really efficiently. I had a lot of interaction there, and also in the Earth Sciences Department at Melbourne University – it was very much a multidisciplinary project.

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Postgraduate metallurgy: the best of both worlds, semi-industrial and academic

What did you do after Honours?

The Honours year tends to finish around November, so to bridge the gap till university resumed I actually worked as an emergency teacher in the school system for about a month – up at Mildura, where my girlfriend (now my wife) Suzanne was teaching. In the New Year I enrolled in a Masters of Engineering at Melbourne University after my Mum saw an opportunity in the paper for industry-funded postgraduate scholarships. Such scholarships tend to be a little bit more generous, and the fact that this was sponsored basically in the area of metallurgy, seemed to offer some good opportunities.

The study was based at the G K Williams Cooperative Research Centre for Extractive Metallurgy (GKW), which was actually one of the first CRCs. I was enrolled at the Chemical Engineering Department at Melbourne University, but I did all of my experimental work at my third CSIRO division, the Division of Minerals, also in Clayton. I was based there full-time as an 'industrial trainee', but in the view of Melbourne Uni I was a full-time postgraduate student. So I had the best of both worlds, able to see that semi-industrial environment but also maintaining links with the university.

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New twists to oxide foam applications

You were able to convert your Masters into a PhD. Can you explain your PhD work?

I worked on a fairly new area of metallurgy. People tend to think of metallurgy as an old, dusty, dirty type of thing, but new technologies coming on line are going to change the very way we make metal and the way we recycle.

One of the important things when you're making the metal in the 'primary' or smelting phase is oxide foams. These are just like the foams you get when you're washing dishes, except they're about 1500 or 1600 degrees Celsius – sometimes close to 2000 degrees. They're very, very hot. And they are made of silicates, like lava from a volcano. The interesting thing about these foams is that when you inject gas to make the metal from the iron ore, you get a very large surface area in the foam, which is great for improving heat transfer from post-combustion. That cuts down the greenhouse gas emissions by a great deal, as well as speeding up the reaction kinetics, increasing the throughput rate for an economic benefit as well as an environmental one.

I took a fundamental approach, but in work that hadn't been done before. I withdrew hot bubble films using wire frames, rather like dipping a coathanger into a bucket of soap solution to look at the colours of the film on the frame. We did this in the lab at a very small scale to simulate a hot bubble. Then, using a Michaelson laser interferometer, we were able to design and use some laser techniques for the first time ever on hot bubbles, to measure their thickness as they drained and also how long they took to rupture and how thin they got before they ruptured.

This told us a lot about how to control these foams, how to change the chemistry to optimise them. In reality the foam can sometimes just start violently ejecting from the furnace – that is very dangerous and also causes down time and loss of productivity. Or the flipside is that the foam can sometimes disappear to nothing, so that suddenly you will burn out a lot of the heat lining of your vessel, a lot of the equipment. So even though it was such a fundamental PhD, industry were interested to understand what stabilises these hot foams, which they realise are now pretty much the key to all new smelting technology.

As a result of your PhD work you received an invitation to address the Royal Society, in London. That must have been a wonderful experience.

It was, mainly because that is a fairly selective venue. (They don't have 'conferences', they have 'discussion meetings', basically by invitation.) I received an invitation from one of the Fellows to attend a discussion meeting, so in 1997 I presented my PhD work before I had even written it up – I was one of the few non-professors there to present my work to that august audience. I did finish writing up my PhD later that year, but that experience is very much the highlight of my scientific career so far.

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Inspired projects in mixing and separating metal phases

What did you do after completing your PhD?

I stayed on at the CSIRO Division of Minerals. I had some offers to do a postdoctoral fellowship in the US and the UK, but partly for reasons of job security I decided to stay. I have managed to maintain the links with those institutions and visit anyway, basically getting the sort of interaction I would have got as a postdoc. At CSIRO I managed to get a position as research scientist, in effect circumventing the postdoctoral level and going straight into the project level.

I am currently working on many, many projects, as project leader and also now senior research scientist/engineer. I do a multitude of contract projects, which we would call externally funded work – from both international and local companies – for probably 30 or 40 per cent of my time. The other 60 to 70 per cent would be the government funded, 'blue-sky' research, which is generally long-term, looking at trying to solve problems maybe 10 years hence, whereas the industry funding tends to be to solve day-by-day issues.

What sorts of projects have you got going?

I've got a couple that I can't talk about, but generally the theme of those sorts of projects is waste immobilisation – for example, using molten oxides to trap nasties like arsenic and lead, making them basically silicate oxides (called 'slag' in the metallurgical industry). They are essentially what you dig up out of the ground, so they become like geopolymers. You can immobilise toxins in slags and then put them in the ground, and we do leaching tests to see how environmentally stable they are. That's a booming area of work, as you would imagine.

Other areas I'm looking at include phase mixing. Just as you might make salad dressing at home, usually as a bottle of vinegar with oil, and often the two liquids will not mix until you shake them, so we want to bring the two phases – for example, oxide and metal – to mix together in a metallurgical vessel so as to get a good fast reaction. But then we want to look at ways to make those phases separate as fast as possible, so we can tap off the metal product with minimum impurities. That has both economic and also environmental implications, because the more efficient you can make that reaction, the fewer raw materials you need for a given output. The mixing of liquids and foams has been probably my main focus, and it has led to some other interesting new research areas also.

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Defying gravity: container-less melting for impurity-free measurements

Would 'container-less levitation' be one of those other areas of research?

Yes. In this relatively new method we use very high frequency radio waves, about 400 kilohertz, to melt and actually levitate pieces of metal. You can use these radio waves to generate a very high current in a copper coil, a bit like a transformer coil. If you put a piece of metal – maybe one or two grams, not all that large – inside this coil, quite amazingly it will just suspend itself in air.

We call this melting or levitation 'container-less' because the metal sample now is not sitting in any crucible from which it could pick up impurities. The advantage is that we can do very accurate measurements on the surfaces of liquid metals without any influence from impurities. For example, we can measure the surface tension of the levitated metal and see how it changes with the oxygen partial pressure. That is, we can simulate how the oxygen in a metallurgical vessel gets less and less as you go deeper towards the metal – we can see how the surface tension changes, to help us predict how phases will mix in current processes or new ones.

Did your recent overseas visit relate to this work?

It did. As part of the Scientific Visits to Europe program of the Australian Academy of Science I received a grant to go to Germany, and at the invitation of some people that I had networked with at the German aerospace research centre in Cologne, near Bonn, I went there as a visiting scientist for one month. (I have just got back.) That group has sent experiments up on the microgravity research laboratories with NASA – into space on the Shuttle, and up on things like sounding rockets and the parabolic flights, the so-called 'Vomit Comets'.

It was very exciting. I was able to work there with them, learn about their new techniques, and look for ways to build German-Australian bilateral links and, hopefully, get involved in microgravity processing of materials. That is really another way of levitating metals. I have been levitating them on Earth by using radio waves, but if you use the microgravity on the international space station you need only heat the samples and do experiments. The idea is to look at advanced materials – how to make new metal alloys much cleaner, things like this – to get ideas for processing them back on Earth, so that when you do make ultra-strong alloys you don't have the impurities or the fatigue problems that you might get with aerospace alloys.

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A potent mix: networking, travel and the excitement of scientific discovery

What skills do you think are needed in science today?

Probably the technical aspect has never been my greatest forte. I tend to remember what I have heard or read, but I've never been one to bury myself in maths or anything like that to understand the root of a problem. I guess what has been most successful for me is the networking – to see what is out there, to take the blinders off and look across disciplines at the physics and chemistry, for example, of bubbles and phases and mixing. It doesn't matter whether you're talking about flotation of minerals or about smelting, the physics and chemistry are the same. I've tended to try and break down that barrier and have an open mind, to network quite widely. I think that's the main thing.

You tend to identify 'gatekeepers', people who can open doors, who can write that reference or can give you that advice, be the sounding-board, to help you with either your next proposal or your next idea. So something that has been really important in helping advance my career is to seek out a mentor or a coach and draw on their expertise, using them as a trusted adviser.

What do you see as the most rewarding or exciting aspects of a career in science?

Oh, I'd be lying if I didn't say it was the travel. The international travel is fantastic. You tend to go to places that you might not go to for just a holiday. For example, I've been to Germany a couple of times and also to Stockholm, in Sweden, to Helsinki, in Finland, and to the UK a few times – as well as to places like Hawaii where you probably would indeed go for a holiday. In travelling you are experiencing the different cultures, and also the language of science has always been very international, very globalised. For me that's exciting, because you are always talking to different cultures but at the same time you are talking a common language. There is a great sense of both discovery and networking.

The fundamental science is really about that discovery and the sense of ownership or empowerment that you get when you work with a team and come up with some good ideas, and then see them through. And if you can get something through to commercialisation – I haven't done that yet, but it is one of my goals – it should be very rewarding to be able to say, 'Yes, we came up with that idea and we carried it all the way through to a spin-off.'

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A sustaining multiplicity of life interests

Your research is clearly a very important part of your life, but as we said you have had a range of other interests as well. What are some of these?

I like to eat! I like to go to restaurants and eat different foods. A very strong hobby at school was martial arts – some judo, some tae kwon do – and nowadays I am a fairly keen scuba diver and alpine skier.

Music has probably been my biggest interest. I started playing organ at about five and progressed to piano and music theory, and when I went to high school I also did trumpet, playing in a concert band. We did the usual Gilbert and Sullivan types of production – The Pirates of Penzance, and things like this – and every year I managed to score a role. I enjoyed the arts side of things.

A lot of the time now I like to play in a band with my brother. He still lives in the country, in Shepparton, and I try to get up there maybe once every month or six weeks and do a band gig at a pub. That's always good fun, because you either bump into somebody you know or because you're in some small town where nobody knows you, you can let off a bit of steam. I think in life you need some degree of multiplicity, and so the band is a good way for me to experience something else outside my blue-sky or industry-type work. It's nice to be able to just go up there and have a good time and still play with my brother, drawing on a lot of the skills and the songs we might have played when we were teenagers in the bedroom.

Unfortunately we're probably a two- or three-hour drive away from my immediate family – my parents and my sister also live up in Shepparton – but we tend to see a lot of each other. They're always coming and bedding down at my place, for example to make use of the shopping in Melbourne. Basically we're a very close family.

My wife Suzanne and I have a son, Harvey, and she is expecting another child in a couple of months' time. That's kept me very busy. Suzanne is a science teacher – we met during the teaching course – so besides our personal interests we share a professional interest.

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Developing and sharing ideas for the future

Where do you see yourself in 10 years' time?

That's a good question! Throughout my career I've always had a three- or five-year plan, looking to that next degree, that next visit or something like that. But I think after about 10 years I would have maybe two options – which could be poles apart, although I am hoping to bridge the gap. One would be to get involved more in the commercialisation of ideas. I have some good ideas of my own, but I tend to be reasonably good at drawing together a critical mass and then, hopefully, seeing those ideas through. Given my technical background and those networks, maybe I could get involved more on the commercial side, which tends to involve a lot more human – less clinical, if you like – interaction. That is, basically you can get out and wheel and deal, and organise things like funding and testing in trials. That's something I would really like to get into.

The flipside, which is not mutually exclusive to that, could be lecturing at a university. (I still have a desire to teach, and getting that degree hasn't come back to haunt me.) At the same time, it gives you a sense of empowerment to start some research group, take on students and act as a mentor to them, trying to help them if they're interested in pursuing science or engineering or technology as a career – just to do what you can to help stimulate that.

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