Theoretical And Experimental Study On Dry Centrifugal Granulation Of Blast Furnace Slag

Blast furnace slag is the main by-product in the process of smelting the pig iron. There is 0.3 to 0.6 tons of blast furnace slag when every 1 ton of pig iron is produced. Nowadays, the technology of water quenching to treat blast furnace slag exists serious problems that cause environmental pollution and energy waste. It results in heat waste of about 10 millions tons of standard coal and 400 thousands tons of harmful air polluting emissions such as H2S, SO2. It is the current research focus that studying dry slag treatment technology to recycle slag waste heat efficiently.The paper studied theory and experiment of centrifugal granulation of blast furnace slag. By establishing blast furnace slag dry centrifugal granulation mathematic model and slag particles coagulation thermodynamic model , the paper studied the key parameters such as centrifugal granulation device structure, granulation device speed, temperature of molten slag, flow rate of molten slag, flow rate of heat transfer medium, initial temperature of heat transfer medium, which impacted on the slag granulation particle diameter. Then we mastered centrifugal fragmentation theory of blast furnace slag and coagulation thermodynamics theory of slag particles. Processes of slag granulation and coagulation were simulated by FLUENT software to study the key parameters such as air flow rate, granulation particle diameter, temperature of air, which impacted on particle coagulation rate. The simulation results and analysis show that slag granulation particle diameter and flow rate of air are two major factors to affect particle cooling process. Experimental test-bed of dry centrifugal granulation of blast furnace slag is established. Based on the experimental test-bed, we carried on experiments of centrifugal granulation of blast furnace slag under the speed of 800r/min, 1300r/min, 1800r/min,2300r/min. The experiments verify the theory of dry centrifugal granulation of blast furnace slag and the simulation results of particle coagulation.Dry slag centrifugal granulation is a complex liquid-solid two-phase conversion process. The keys to this study are blast furnace slag centrifugal granulation mechanism and particle curing mechanism. It is of great significance to master them so as to provide guidance to carry out blast furnace slag dry treatment process design and waste heat recovery process design.