Electro-Slag Refining


During my last three years at university, there was only one other person doing metallurgy in my year, and that was a person called Charles Gheenen. For his thesis he decided to do some work at Professor Dilewijns’ laboratory, which involved working on the new Electro-Slag Refining (ESR) equipment they had acquired in their off-site premises in Zwijnaarde.

I see that Wikipedia calls it “Electro-slag Remelting”, but essentially it involves letting a current go through a molten slag between a bar of steel (the one to be refined) and the baseplate, where the bar of steel gradually melts and deposits itself onto the baseplate, leaving most of its impurities behind in the slag. I seem to remember that it was being used on an industrial scale in Russia, but I’m not aware that it’s much in vogue n the current steel industry, where making clean steel is produced through processes such as vacuum degassing stations.

Anyhow, Charles did a great job on hoovering up most of the literature on the subject, and since throughout his thesis year they had very little luck in producing any electro-refined steel, the literature survey took up the lion’s share of his thesis. Charles was also employed for a while by Prof. Dilewijns’ laboratory as a researcher, starting a little bit earlier than I did, and seeing as he had done the initial work on ESR was the natural person to head the sequel thesis done by a student whose name escapes me now.

This student was now in the unenviable situation that there was very little literature left for him to the first part of his thesis that hadn’t already been covered in the thesis that Charles had written. Although in the end he was more successful in producing actual steel from the equipment, there wasn’t much of it and surely not enough to come to many conclusion of how it affected the steel properties.

On top of that, Charles left his position at the laboratory for Union Minières near Antwerp (I think that’s where his father used to work) after only a few months, and I had to take over as leader for the project. I remember going to Zwijnaarde on a number of occasions, and trying out different configurations to sharpen the tip of the steel bar so that we could get the localised current high enough to start the melting process.

At some point there was also a minor panic when the student mentioned the possibility of noxious gases emanating from the molten slag, so we had to wear gas masks with microphones in them so that we could communicate between some of the workers on the top platform and those observing the process from below. I also remember that the first time we were successful we came back in triumph, declaring “we have a little one !” (referring to the fact that although successful, the resulting refined steel was less than a foot in length).

All in all, the student in question just scraped through for his thesis with 50% of the points, which confirmed in my mind that it’s not a good thing to do a follow-up thesis, since yours will always be compared, and often unfavourably, with that of your predecessor (Charles’ thesis received a rating of 70%).

I’m not sure what happened to the Electro-Slag Refining equipment. At no time in my subsequent time at Prof. Dilewijns’ laboratory did I hear any further mention of it. Had the equipment been on loan, and had been returned from where it came from ? Whatever the case, as I’ve mentioned earlier, I think subsequent developments in the steel industry made ESR a superfluous process, unless you wanted to go for small quantities of steel in a super-refined state.

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