Coal-sand attrition system and its` importance in fine coal cleaning. Fifth quarterly report, August 31, 1992--November 30, 1992
The optimal conditions found for both the median size and specific energy for a particular system differ from one another. The fact that the surfaces from which these conditions are estimated are saddle or minimax further complicate the issue as these are characterized by a range of optimum conditions. However, there is no doubt that the conditions which are suitable for optimizing the product particle size may not necessarily be good for the specific energy. Depending on the objective, either the product size or the specific energy may be optimized. Besides, it seems that when the product particle size is optimized, the specific energy is simultaneously constrained. In this manner, a better estimate of the required energy consumption can be obtained for scale-up purposes. When the results in Table 3 are compared with those of the other three coals given in quarterly report numbers 3 and 4, a trend/pattern is observed. For the four coals involved in this work, the degree of fineness of the product particle size depicted by either the median size or d{sub 90} after wet stirred milling, correlates with the hardness or HGI. In other words, the higher the Hardgrove Index, the finer the product particle size. The specific energy in contrast, does not tend to correlate with the hardness or HGI of the coal. Rather, the softer coal, depending on the properties of the associated impurities appears to consume more power. While this may initially appear to be a great surprise, the reasons for it are rather easy to grasp. In order to do this, one needs to look into such things as the properties/characteristics of the respective coal/impurities, the grinding environment, the mechanism of particle breakage in the mill, and how the grinding force is transmitted to the media.
- Research Organization:
- Alabama Univ., University, AL (United States). Mineral Resources Inst.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG22-91PC91280
- OSTI ID:
- 10133315
- Report Number(s):
- DOE/PC/91280-T6; ON: DE93009699
- Resource Relation:
- Other Information: PBD: 7 Jan 1993
- Country of Publication:
- United States
- Language:
- English
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