Cement clinker makes up for 95 percent of the material used to make cement. Clinker is a synthetic rock that is the result of the granulization of limestone (decalcinated into lime), fly ash or clay in a kiln reaching 1450°C. The clinker is combined with gypsum and ground to a very fine particle size of less than 45 mm. Hence size reduction is of vital importance in the design of a cement manufacturing process. Additionally, the structural characteristics of cement clinker can vary significantly between different plants, which can result in a variation of the grindability properties. As comminution (size reduction of particles) accounts for 40 percent of the total power usage for the entire cement manufacturing process it is critical that size reduction units are optimized. (Benzer, Genc, Levent Ergun, Oner, 2002)
The following report is designed to assess both the Grindability of several cement clinkers using a modified version of the JK drop weight test and to assess the validity of using such a test for cement clinkers. In addition to these aims, the grindability results were compared with previous work carried out on the same samples that had undergone drop weight testing for this report. The samples were taken from cement production plants in Kandos, Railton (Portland cement) and Rockhampton (white cement).
The most important information attained from this report was that of the three samples the relative grindability ranking (in ascending order) was: Kandos, Railton, and Rockhampton. It appears that while the two Portland clinkers show some of the expected relationship with their other physico-chemical properties, the Rockhampton clinker behaved in a more unpredictable manner.
The Drop weight test is some what effective at determining the grindability characteristics of cement clinkers. Due to excessive time requirements, and a lack of accuracy for smaller particles the grindability test is not a considerably practical method for assessing the grindability of cement clinker on an industrial level.