Mill Performance of Coal Blends
This paper focuses on determining the size distribution of the organic and mineral matter components of a coal blend based on the known pulverising characteristics of the parent coals.
Evaluating the potential performance of coal blends in both the thermal and PCI market requires knowledge of the size distribution of the organic and mineral matter components of a blend, especially when there are significant differences in the HGI of the component coals. The size distribution of the organic matter impacts on combustibility of thermal and PCI coal blends and handleability of PCI coal blends, whereas, the size distribution of inorganic matter impacts on the slagging and fouling of thermal coal blends.
Petrography techniques were used to examine four sized fractions from the PF of single coals and blends. Also, QEMSCAN, developed by CSIRO, was used for the identification of minerals in the PF of some single coals and their blends.
The results show that, in most cases, the milling characteristics of individual coals and their maceral groups do not change when they are blended with other coals. The exception is when a very soft coal (HGI 90) is blended with a very hard coal (HGI 35). In this case preferential milling of the softer coal occurred.