Feature: Chemical Engineering
Murray Gray is leading a research network that seeks to eliminate tailings ponds of bitumen waste from the Northern Alberta landscape.
By Tyler Irving
Can research, innovation and clever chemical engineering overcome the environmental challenges facing Alberta’s oil sands industry? Murray Gray believes they can. Gray is the scientific director of the Centre for Oil Sands Innovation (COSI), a multi-million dollar network dedicated to funding breakthrough research that will eliminate oil sands tailings ponds and greatly speed up the reclamation of land disturbed by mining operations. Based at the University of Alberta, COSI celebrated its fifth anniversary of operation this year. ACCN spoke with Gray to find out more about his vision for sustainable oil sands.
ACCN Is there such a thing as sustainable oil sands development?
MG If you look at the most widely accepted definition of sustainability from the United Nations’ Brundtland Commission, it talks about sustaining communities and maintaining a long-term natural environment for local people. It doesn’t preclude use of fossil fuels. From that perspective, what you’re looking at is not to make the oil sands renewable, but to minimize the impact on the local environment.
One of the biggest problems that the industry faces right now is with tailings. The current practice is to accumulate wet tailings materials until the mine is played out and then put that material back into the mine site. That gives a very long delay time between when the mine first starts operation and when serious reclamation work can begin. Our biggest single research program is focused on trying to extract the bitumen without using water. It would essentially eliminate this problem; you still have the sand and the clay, but if it’s dry it can go back in the mine immediately.
ACCN How do tailings form in the first place?
MG Bitumen is a naturally occurring, highly biodegraded crude oil. The current mining operations extract this from the oil sands by digging up the sand and mixing it with warm water. The bitumen is melted as it warms up, then it releases from the sand and attaches to air bubbles. That material is collected as a froth, which is then cleaned up to remove the water and mineral particles and sent for upgrading.
When you mix the oilsand ore with water you get sand, which is no problem, but you also take any clay that’s in the ore and disperse it. Those fine clay solids do not easily release water, so they form a huge volume of water-rich sludge which does not re-compact nicely. You can’t just put sludgy paste back into the mine so it accumulates in tailings ponds over the mine’s life span. As well, some of the components of bitumen dissolve in water at low concentrations and those are toxic to aquatic organisms. At present, the water is intensively recycled. In the future, some of that water will have to be released and so there’s an interest in technology for treating it.
ACCN What kind of research are you focusing on to deal with this problem?
MG Most of our work is on the fundamental properties of the oil and how it interacts with clays. One major problem is that high molecular weight molecules in the bitumen bind to each other, forming aggregates. This aggregation is very important in terms of how the oil dissolves and how it releases from minerals. We’re working on understanding the basic molecular structure, how these molecules aggregate and how they stick to surfaces.
On the non-aqueous extraction side we have several projects looking at using different solvents to extract material instead of using water. It’s a two-step problem: you want to get the bitumen away from the mineral material and then you have to clean up the bitumen to remove any suspended solids. We’re looking at a whole range of solvents but whatever ones we use, we have to be very sure of what happens if they go back into the environment.
ACCN People have been working with bitumen for more than 60 years, why do we still need fundamental research?
MG Bitumen is an extraordinarily complex mixture that defies proper analysis. It contains millions of different components and that’s a conservative estimate. The molecular weight isn’t all that high, in the range of 1,000 to 3,000 daltons, but the aggregation makes measuring properties and doing chemical analysis very challenging. We’re making progress: we have new tools that we can use to probe interfacial behaviour and we can use techniques from nanotechnology to better understand what’s happening with these molecules at interfaces. But we’re still not there and, as it stands, nobody in the world has the capability of completely analyzing one of these mixtures.
Another factor is a big change that has come from the industry side. When the oil sands mining industry started, nobody was too worried about wet tailings. Now, the companies understand that there’s a huge cost associated with that practice. When you change the ground rules, you open up a lot of possibilities for new approaches. So techniques that were rejected in the past as too expensive now have tremendous potential.
ACCN What prompted the creation of the Centre for Oil Sands Innovation?
MG The centre was initially started in partnership with Imperial Oil, which wanted new technologies because the current practices of the industry were not sustainable enough. They committed $10 million over a period of five years. They’ve subsequently renewed that commitment for the next five years, so they’ve committed $20 million in total.
After that, we were able to get two provincial agencies on board: Alberta Ingenuity and the Alberta Energy Research Institute, which has since been restructured as Alberta Innovates, Energy and Environmental Solutions. The commitment from Alberta Ingenuity was in the range of $7 million over five years and the commitment from Alberta Energy and Research Institute was in the range of $10 million over five years.
Murray Gray, scientific director of the Centre for Oil Sands Innovation, holds up a sample of cracked bitumen that is being prepared for injection into a gas chromatograph. Understanding the fundamental properties of bitumen and its interactions with sand and clay could help industry deal with the problem of wet tailings.
ACCN How has the centre evolved over the past five years?
MG As we expanded the program and developed major initiatives looking at non-aqueous extraction and new technologies for upgrading, we quickly realized that we couldn’t just focus on one group of people at one university. So we started organizing projects with collaborating universities.
One example is Keng Chou at the University of British Columbia, who’s using unique spectroscopic techniques to understand the structure of water, solvents and bitumen at the interfaces with solids like silicon dioxide, which mimics some of the minerals of the oil sands. By using non-linear spectroscopic techniques, he can cancel out the signals from the bulk liquid and look only at the material that’s immediately at the interface. Given that our major objective in recovering bitumen is to get it off of clay and sand surfaces, that kind of scientific insight is very important.
Another is Juliana Ramsay’s group at Queen’s University. They’re using microorganisms to degrade some of the soluble components that go into the water in the oil sands. A tiny fraction of the bitumen will dissolve in water and those components that dissolve are toxic to aquatic organisms. But they’re also biodegradable, so the team is trying to develop novel bioreactors and active bacterial cultures that will rapidly degrade those components.
ACCN How do you expect your industrial and government partnerships will change?
MG The big change over the past number of years has been a growing realization of just how big an issue the tailings ponds are for the oil sands industry. Earlier this year, all of the oil sands companies signed an accord in which they agreed to share all of their technology, data and research and development on trying to deal with wet tailings. As a result, one of the new initiatives that we’re starting is a theme on aqueous tailings in partnership with Imperial Oil and all the other oil sands companies. That’s a new initiative and it’s part of our proposal to the government of Alberta to renew funding for our centre for another five years.
ACCN What do you say to skeptics who doubt the industry’s ability to make good on sustainability?
MG The environmental groups typically don’t like big industry so there’s a political component there. But there are also a number of misconceptions, for example, the issue of acid mine drainage. In other mines, the extraction and milling of the ore pulverizes minerals that contain sulphur. The sulphur oxidizes and is released into ground water as acid, which then leaches out heavy metals. That whole cycle is irrelevant in the oil sands; the kinds of components in the tailings are radically different from what you get in any other mining operation. Yet people have written a number of times about the toxicity of acid tailings in the oil sands when in fact the pH is 8.5.
Then you have to look at what has been proposed in terms of the time frame. These mines are planned on a 20-to 30-year cycle, so you can’t go in after five years and say, “You’ve made a big mess, why isn’t it all reclaimed?” When people who have never visited a mine in their life see the oil sands they’re horrified at all the destruction, but they’re not paying attention to the efforts being made. Companies are being successful in reclamation, the problem is the time lag. Last fall, Suncor successfully reclaimed its first tailings pond, which was first put into service in 1967, so that’s the timeline that I’m concerned about. The industry clearly needs to step up and reclaim much more quickly.
ACCN When you look back at the past five years, what are you most proud of?
MG My biggest source of pride is in developing a multi-university, multi-disciplinary network of people who are committed to making a difference. Canada has a wonderful resource opportunity but has to use it wisely. Clearly we need to do research and understand the fundamentals in order to create a foundation to have much more sustainable oil sands technology. The experience of recruiting interested scientists and engineers from across Canada has been very exciting and I think that’s probably the single biggest satisfaction.
ACCN How will you measure success?
MG I’d like to see two or three major technologies rolled out. It obviously takes time to go from the laboratory to practice but I think we will be in a situation with several technologies being piloted and tested in industry in three to five years. I think that would be a fair measure of success.
Photo Credit: University of Alberta, Faculty of Engineering | Pembina Institute
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