THE APPLICATION OF SIMULTANEOUS TG-DTA TO THE DETERMINATION OF THE FATE OF INJECTED COAL IN A PILOT-SCALE BLAST-FURNACE SIMULATION RIG

Coal injection is an important technique for increasing the efficiency of blast furnaces, although the required optimum properties of inject ant coals have not yet been fully identified. The Single-Tuyere Coal I njection Investigation Rig at the British Steel Teesside Technology Ce ntre is a pilot-scale blast furnace simulation operated without iron o re so that the combustion (and gasification) of the injected coal can be studied in isolation. About two tonnes of coke are used to create a realistic simulation of the blast furnace raceway. Coal is injected i nto the hot air blast, and changes in the raceway conditions observed. Carryover fines from the waste gas are collected during the trial, an d at the end of the trial, the coke bed is cooled, and coke samples du g out. These solid materials are analysed for traces of the injected c oal, in order to assess the efficiency with which the injected coal is combusted. The determination of the proportion of injected coal char present in these samples was originally carried out by point-counting particles using optical microscopy. This technique is labour-intensive and subjective. An alternative technique has therefore been devised, employing simultaneous thermogravimetry-differential thermal analysis (TG-DTA). The technique gives good agreement with optical microscopy, whilst being considerably faster and less subjective. (C) 1997 Elsevie r Science B.V.