Behaviour of selected minerals in an improved ash fusion test: quartz, potassium feldspar, sodium feldspar, kaolinite, illite, calcite, dolomite, siderite, pyrite and apatite

A suite of minerals found in coals were analysed using an improved ash fusi on test, These minerals were quartz, potassium feldspar, sodium feldspar, c alcite, dolomite, siderite, pyrite, kaolinite, illite and apatite. Each spe cimen was also analysed by XRD as an "as-received" specimen, an 800 degrees C product and a 1600 degrees C product. These results allowed evaluation o f the applicability of the improved ash fusion test for determination of ch emical changes occurring in the ash fusion furnace. Phase changes were obse rved in the improved ash fusion test for the Na feldspar, siderite and pyri te specimens. K feldspar movement could, in part, be related to phase chang es. The complex reactions occurring in the illite and kaolinite specimens l imited the interpretation. The calcite and dolomite specimens movement was dominated by reactions of calcite, lime and portlandite. The quartz and apa tite specimens were relatively inert. These results indicate that the impro ved ash fusion test can provide a link between the various standard ash fus ion tests and analytical tools such as XRD to provide enhanced understandin g of the processes occurring in the ash fusion furnace. (C) 1999 Elsevier S cience Ltd. All rights reserved.