Cements ground in the vertical roller mill
fulfil the quality requirements of the market
Dipl.-Ing. Th. Fahrland, Dr.-Ing. K.-H. Zysk, Loesche GmbH,
Cement production typically requires the grinding of three separate types of material during the process: the raw ma-terials and coal before the kiln, and the final cement product once firing is complete and the clinker cooled. Looking back on a century or more, ball mill systems were used for all three grinding stages, but the development of more energy-efficient vertical roller mills (VRMs) led to their replacement. Initially, this focused on grinding coal and the cement raw materials, with the adoption of vertical roller mills for cement product grinding – with its finer grinding requirements – coming more recently, in the late 1990s. The main reason for the delay in uptake of VRM technology for cement grinding was the concerns of producers that their product qualities would not meet market requirements, specifically in three key areas: water demand, strength development and setting times. Over the past 15 years, however, it could be demonstrated that these concerns are unfounded, and that the quality of cement obtained from VRM grinding is as good as, or in some cases better than, that produced in a ball mill. In consequence, most of the world’s major cement producers now use vertical roller mills for cement grinding with no hesitation.
Summary CEMENT INTERNATIONAL 02/2013 pp 64-69
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