Prof. Robert Durrer (1880-1978)
Robert Durrer was professor of metallurgy at ETH Zurich from 1943 to 1961. His research was crucial for the development of the basic oxygen process (BOP, or LD-process*) used in high quality steel production.
Until the establishment of the basic oxygen process, crude steel production was about two methods. Lower quality steel was mass produced by blowing air into the Bessemer or Thomas converter. In doing so the impurities of the raw iron were removed by oxidation in little more than a quarter of an hour. The disadvantage of this quick and cheap method was the cooling caused by the nitrogen present in the air. The heat generated by the oxidation was just about enough to keep the newly generated steel above its melting point. The addition of scrap metal in terms of recycling was not possible. Simultaneously, the uptake of nitrogen led to embrittlement, making this lower quality steel useful only for less demanding applications. High quality steel could only be produced via the expensive Siemens-Martin process, during which the impurities are burnt out from the pig iron in a shallow hearth furnace. Since the oxidation happens indirectly through the slag formed above the molten metal, the steel is not exposed to excessive nitrogen. At the same time the duration of the process (several hours) allowed for an exact adjustment of the steel composition despite the then slow analytical methods. This was a prerequisite for the production of quality steel. As the open-hearth furnace was heated mainly by gas or oil combustion, scrap metal could be added at large scale. This initial situation - on the one hand a quick and cheap process for low quality products and on the other hand an expensive and slow process for high quality steels – triggered many new ideas in researchers. Robert Durrer takes a prominent position among those.
In 1943 Durrer was elected professor of metallurgy at ETH Zurich and at the same time member of the Board of Directors of Von Roll AG, the largest steel producer in Switzerland at that time. Together with his assistant Heinrich Hellbrügge he conducted the first experiments with a water-cooled oxygen lance in a small laboratory induction furnace at ETH Zurich. Later he obtained a 2.5 t copper converter in the U.S., which was then equipped with a diagonally-blowing oxygen lance at Von Roll. In May 1948, the company magazine was able to report that for the first time in Switzerland steel had been produced by blowing pure oxygen onto the molten pig iron, with half of the batch consisting of scrap steel. This demonstrated the potential of this new method in overcoming the disadvantages of the previous processes, that is, that quality steel production could become faster and at the same time cheaper.
After the Second World War Austria and its industry was war-ravaged. This was also true for the former Hermann Göring plant, which now developed into Austria's largest steel producer under the name VOEST. The Austrian tradition called for quality steel, however, this implied the investment into an open-hearth furnace, which was at that time impossible for the poor country. In this situation the plant manager of VOEST, Helmut Trenkler, was approached by Durrer and Hellbrügge who informed him about their new method, with which quality steel production would become cheaper. A few weeks later the companies Von Roll, VOEST in Linz and Alpine in Donawitz signed a contract. The experiments carried out in Linz under Theodor Eduard Süss until 1949 allowed for the further development of the process, so that on 27 November 1952 two new 30 t-converters went into service. From this point on the new method could finally take off on its triumphant advance around the world.
Robert Durrer's great contributions to steel production were honored by the AIME Benjamin F. Fairless Award in 1966. He was also the editor and co-author of the classic multi-volume edition "The Metallurgy of Iron", also called " Gmelin-Durrer".
*) The majority of today's steel production is associated with the name "LD-process". In general the "LD" is interpreted as "Linz-Donawitz" even though according to the original agreement it should have been "Linz-Durrer". Even so, the name Durrer will remain associated for all time with one of the most important metallurgical processes. At the same time it is noteworthy that this process was, although crucial for the industrial progress, not developed in one of the big countries in metallurgy, such as Germany, England or the US, but in the small alpine countries of Switzerland and Austria.
Prof. Dr. Heinrich K. Feichtinger, professor emeritus at the Department of Materials