THE BEHAVIOR OF COAL MINERAL CARBONATES IN A SIMULATED COAL FLAME

The flame behaviour of the most important carbonates in European impor t coals has been investigated. The flame tests were performed in a lab oratory facility in which the environment of a coal burner was simulat ed. For the tests the coal minerals were separated from the coal by fl oat-sink separation. Electron microscopy was used to determine the siz e and morphology of the particles sampled from the flame. The viscosit y of the particles was derived from tests of their adherence to refrac tory deposit plates placed in the flame. Calcite (CaCO3) particles of 60 mu m, a typical size in pulverized coal, broke up into fragments ap proximately ten times smaller. The rime taken for complete fragmentati on corresponded to the time calculated for the decomposition of the ca lcite, None of the 'siderite' samples tested showed fragmentation. Det ailed analyses with TGA MS (thermogravimetry coupled with mass spectro metry) were performed to determine the actual fraction of FeCO3 in the 'siderite' samples. Flame products of siderite proper had high viscos ity. Siderite particles with embedded silicates had flame products of low viscosity, Ankerite (CaFe(CO3)(2)) did not fragment and the flame product was fluid.