Distribution characteristics of burden in low shaft furnace

Even distribution and descent of raw materials in the blast furnace stack ensure uniformity of gas flow and improve the fuel rate. To improve the smelting efficiency in the low shaft furnace, the distribution patterns of various raw materials were determined in a previously designed and fabricated half scale model of the actual 12-15 tonnes per day low shaft furnace. The angle of repose of the individual raw material composing the burden and the composite burden were measured. The distribution behaviours were mapped separately with individual constituent composing the burden and also with a few typical composite burdens employed during smelting trials, with or without admission of air blast. The charging device of the low-shaft furnace consists of two drums, the undirectional rotation of which feeds the raw material to the furnace, unlike the conventional blast furnace where the charging device consists of small and big bell. In the scaled model the direction of rotation of the charging drum was alternately reversed to assess its effect on the distribution pattern. The denser and small particles remained at the place of fall inside the model while bigger particles rolled down the slope forming the final contour. The variations in ore quality showed a difference in the type of contours obtained. (Mr. K.N. Gupta, Scientist, Dr. A.B. Chatterjea, Scientist, National Metallurgical Laboratory, Jamshedpur