Vertical Section Observation of the Solid Flow in a Blast Furnace with a Cutting Method

The solid flow plays an important role in blast furnace (BF) ironmaking. In the paper, the descending behavior of solid flow in BFs was investigated by a cold experimental BF model and numerical simulation via the discrete element method (DEM). To eliminate the flat wall effect on the structure of solid flow in lab observations, a cutting method was developed to observe the vertical section of the solid flow by inserting a transparent plate into the experimental BF model. Both the experimental and numerical results indicated that plug flow is the main solid flow pattern in the upper and middle zones of BFs during burden descending. Meanwhile, a slight convergence flow and a deadman zone form at the lower part of the bosh. In addition, the boundary between the plug flow and convergence flow in BFs was determined by analyzing the velocity of the burden in vertical directions and the Wilcox-Swailes coefficient (U-ws). The results indicated that the U-ws can be defined as a critical value to determine the solid flow patterns. When U-ws >= 0.65, the plug flow is dominant. When U-ws < 0.65, the convergence flow is dominant. The findings may have important implications to understand the structure of the solid flow in BFs.