Coal devolatilization in bath smelting slags

In this study a technique for selecting large coal particles enriched in a particular coal maceral and an experimental technique for measuring the devolatilization rates of large coal particles were developed. The results of the devolatilization experiments were corroborated by real time x-ray imaging of coal particle devolatilization. In addition a model was developed to determine the effects of devolatilization; coal heating and drying and coal fines carry over while the coal is added to a bath smelter. The model divided the overall smelter into two parts, the smelter system itself and the gas above the slag. From this model the effects of the reactions of the coal before entering the smelting system on the overall process were determined.; It was found that the rates of devolatilization for the low rank coals were roughly independent of the coal chemistry in terms of fraction devolatilized per second, while those for the anthracite coal were somewhat faster. The results were the same whether the devolatilization was carried out in the slag phase or gas phase. The x-ray results show an intense agitation of the slag phase for all the coals which has implications in the foaming production and destruction. Devolatilization times observed in the x-ray imaging experiments were the same observed in the CVPI. The rates of devolatilization as well as the type of volatile products evolved showed an enormous influence from the heating rate. The increase in coal size significantly increased the time of devolatilization with an exponential relationship between the total time of devolatilization and coal size.; A series of situations were simulated using the model to show the influence of volatile matter lost and coal fines carried over into the stack region of a bath smelting reactor on the pose combustion ratio (PCR), heat transfer efficiency (HTG) and coal consumption. These simulations indicated that the combined influence of coal dehydration, coal preheating and coal devolatilization is beneficial to the bath smelting process in that coal consumption decreases. (Abstract shortened with permission of author.)...