I'm Ray Longbottom I'm a Research Fellow in the Steel Research Hub. I'm part of Program D which is Sustainable Steel Manufacturing and my project is on recycling steel plant byproducts.
One of my main focuses has been on steelmaking dust, which contains useful components such as iron and fluxes, but also contains zinc, which is quite a harmful thing for the process. In terms of steel making dust, they currently produce about 20 thousand tonnes a year in the stockpiles the steel making dust undergoes a process called self sintering, where the material heats up autonomously in the stockpiles, agglomerates, and becomes stronger, which makes it easier to recycle. This process was very inconsistent. What we've been looking at is what's happening, why it happens, and how we can make it happen more consistently.
I've been heating up the steelmaking dust's in the air to 1000 degrees and we'll be using the TGA or TGDSC which gives me the mass change and the entropy of reactions. And using those two bits of information, I can work out what reactions are occurring at what temperatures. We measured the moisture content to be around 15 percent. This is very unusual worldwide usually it's up around about, say, 50 percent moisture and if the moisture content of the steel making dusting is so low is one of the reasons why it reacts at low temperatures.
The byproducts at the steel plant are quite variable. The favors and the composition change with time and practice. So what we've done is we've collected samples over quite a long period of time and characterise them all in using just fairly basic techniques like XID microscopy, XRF, a combination of phases, methodology, and see how that changes with the time of practice at a plant, which is information they didn't really have before. One of the key highlights from my project has been working out what reactions were occurring from the steelmaking dust. What we found out was that until I have gone inside, the steelmaking dust was very, very fine were talking around about 200-300 nanometres. They gave it a very high reactivity with air, which meant that it reacted starting at very low temperatures, about 120 degrees to 200 degrees it started oxidizing and heating itself up.