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Show and Lee, 1982; Huffman and Huggins, 1984). The calibration and data analysis procedures used in the present work have been described by Loehden (1988). The relationship of the size distribution of ash particles collected at the furnace exit to the size distribution of minerals in the pulverized coal was discussed by Sayre (1988). Estimates of particle compositions were obtained from the energy dispersive X-ray spectra at the centroids of random cross sections of particles in potted and polished samples. A ternary diagram of the relative amounts of Si02, A'£203, and base (primarily FeO, but also including CaO, MgO, K20, and Na20) in individual particles of the sample collected at the furnace exit is shown in Figure 4. This distribution is useful as a qualitative indicator of the degree of segregation and relative abundance of particle types. The particles may be very roughly divided into three categories: 1. Nearly pure silica derived from quartz, near the top vertex, 2. Particles having a silica/alumina ratio corresponding approximately to mullite, with small amounts of base, and 3. Particles containing larger amounts of base, distributed over a broad band from the base vertex to the region of mullite. As will be seen shortly, the iron content of the particles is strongly correlated with initial deposit formation. In order to interpret the deposition measurements, a quantitative measure of the distribution of iron among the particles will be more useful than the ternary diagram of Figure 4. The mass fractions of particles having specified iron content (as Fe203) are shown in Figure 5. This diagram may be viewed as having been constructed by determining the iron content of the particles in strips cut from the ternary diagram along lines parallel to the Si02-A'£203 side. By far the most ash is found in the 0 14 |