Professor Klaus Schönert (1927-2011) developer of High Pressure Grinding Rolls (HPGR) will be inducted in the comminution category at the gala dinner in the Brown Palace Hotel, Denver on February 16 (www.im-halloffame.com). Its acceptance has verified the claim from the original research that high pressure comminution improved energy efficiency. The rapid growth in applications for minerals has occurred only during the past 10 years because techniques had to be developed to minimise abrasive wear of the rolls.
Cement grew rapidly during the 20th century as the material of choice for the construction of buildings and infrastructure. About 100 kWh were required to produce 1 t of finished cement with about 60% being used for grinding, usually in a two compartment ball mill.
In 1955 Hans Rumpf (1911-1976) was appointed Professor of Mechanical Processing Technology at the University of Karlsruhe and he established a Fine Particle Research Institute. In 1976, during a lecture to the Fine Particle Society in England, he commented that energy use in comminution could be reduced by up to 90% by crushing single particles instead of materials in bulk.
He was succeeded by his student Schönert who continued the research of the Institute on the breakage of single particles in the range 100 µm to 3 mm. Many pressures were used in tests in the laboratory and briquettes of fine particles were formed which were deglomerated in a ball mill or impact mill. Schönert showed that high pressure breakage followed by deglomeration required only one third to one half the energy used in a ball mill.
The patents which covered his work were for a high pressure comminution process, not a high pressure roller mill by itself. The advance he claimed was for a two-step process of stressing a bed above 50 MPa followed by deglomeration. This was challenged in courts in Germany, USA and Denmark but his patents were approved in every case.
The high pressure grinding rolls which were part of the patents were licensed to ThyssenKrupp Polysius and KHD for use with cement and minerals. There have been more than 700 installations by Polysius and KHD, and many installations by Koppern and FL Smidth. HPGRs are now an accepted part of comminution technology for minerals as well as cement.
