Bacteria-treated alumina – more information
Naomi McSweeny, the scientist mentioned in the article we posted earlier this week, has kindly answered some of my dumb questions about the process and her breakthrough.
As I explained to Naomi, my knowledge of alumina is that arrives at smelters in big ships. But I will try to bring her answers in a way which helps readers get what it’s about.
Naomi tells me that sodium oxalate is one of the major impurities that must be removed in the process of refining bauxite into alumina. Her breakthrough is that she has not only invented an organic way of doing this, she has identified the particular bacterium that does the job.
At the moment it is removed by showering the part-processed material with more oxalate so that the impurities can be washed out. But then the sodium oxalate has to be stored, as it is not a nice chemical. Another way is to heat the material, but this is costly and adds to the CO2 equation.
I will let Naomi speak for herself. “Instead of the need to store the sodium oxalate (which usually happens in very expensive, confined concrete ponds), the addition of the biological process at this stage of the cycle removes the need to store and also the capital funding required to build these storage facilities.”
“Processes for the biological degradation of oxalate have been previously patented (you can Google them and find them). The difference between those studies and this one is that no one has really defined the microbial populations that are responsible for the degradation. Everyone has taken a very “engineering” point of view – in that they have this idea, they implement it, it works at pilot-scale and so they start a full-scale process without really knowing the biology of the system and in some cases the science know-how and availability of techniques good enough to characterise the bacteria were just not available.”
“This research has not only defined the microbial ecology of the process, but isolated the key oxalate-degrading bacteria. And that is what the media release and the Fresh Science award were about. The description and characterisation of the novel bugs that I have isolated will mean that the process can be replicated at other sites around the world, especially refineries which have low-grade ore associated with high concentrations of humic and fulvic materials like here in Western Australia.”
From her email, I understand that it does not change the equation when it comes to the ratio of bauxite to alumina, nor of the amount of red mud produced, but it does lower the capital and operating cost of making alumina, as well as reduce the environmental impact of alumina refining.
No wonder she has won awards for her research. Naomi tells me she is a PhD student. Looks like that’s in the bag.
Anyone interested in contacting Naomi, she has posted her email address in our comments section.