Because the breakage environment is so different between laboratory and plant, size reduction is not a subject that readily lends itself to the classic technique of conducting basic research and then transferring the results to large-scale operations. But Professor
Dr.-Ing Hans Rumpf showed that the links between empirical and fundamental knowledge could be understood through research, and the work of his research group contributed a great deal to the more efficient use of energy in size reduction.
Rumpf was born in Langenschwalbach, Germany, in 1911 and graduated from the Technical University of Karlsruhe in 1939. From 1936 to 1942 he worked in the dye industry, then for Alpine AG in Augsburg, Germany, from 1942 to 1955, where he designed new machines to grind and classify fine particles. This background gave him the experience needed to direct a new fine-particle research institute at the University of Karlsruhe, where in 1956 he became a professor of mechanical process technology. From 1966 to 1968, he was rector of the university, and, from 1968 to 1971, he served as president of the West German Rector Conference. A measure of the success of the research institute is that, by 1970, it had a staff of 116, including 45 scientists, and graduated 160 students with diplomas and 30 with doctoral degrees. The institute also generated 225 publications.
Comminution science was a main area of research in the laboratory, and studies were carried out on
■ Fracture physics
■ Crushing under controlled conditions with special reference to single-particle crushing, measurement of energy needed for fracture, fragment size distribution, and new surface area produced
■ Mathematical simulation of comminution processes
■ Practical comminution
In 1976, Rumpf reviewed some of the laboratory’s work in a lecture to the Fine Particle Society in England (Rumpf 1977). He commented in the lecture that
In comminution the particles will react individually in a greater measure than in any other process. The reason for this is that the defect and dislocation structure is decisive for the fracture formation. As a result the breaking behaviour will, for example, vary to a great extent with the kind of material and with particle size but can also vary greatly with the same material and particle size…. How much energy can, in fact, be saved can only be determined by systematic tests with single particles.
Rumpf compared the specific energy consumed by materials crushed as single particles and broken in industrial comminution processes. His results are shown in Figure 2.2, which indicate that energy utilization could be improved by a factor of 10 in theory (although it would be less in practice). One of the outcomes of Rumpfs work was the development of high-pressure grinding rolls (HPGRs), which was one of the main successes in new grinding equipment during the 20th century.