Abstract
High initial moisture in converter sludge enhanced the bursting risk during drying and made this process difficult. In this investigation, effects of parameters on their drying properties were studied through orthogonal tests in a baking cup equipped with a cross flow adjusting system to simulate the two stage thermal condition in a travelling grate. The upper layer bursting rate and the bottom layer dehydration rate are considered as main indicators of drying performance. ANOVA results show that factors of temperature in the 2nd drying and time in the 1st drying have remarkable influence on the upper bursting rate, occupying 45.80 and 34.82% of the total contribution. While time and flow rate in the 2nd drying are significant factors on the bottom dehydration rate, accounting for 56.09 and 27.03%. Additionally, the upper bursting rate decreases with the increasing 1st drying time and decreasing 2nd drying temperature. The bottom dehydration rate increases with the increase of 1st drying time, 2nd drying time and 2nd drying flow rate. Under the optimal condition of temperature 150°C, flow rate 1.5 m s−1, time 9 min in the 1st drying stage, and temperature 200°C, flow rate 1.5 m s−1, time 6 min in the 2nd stage, no burst occurs, and the bottom dehydration rate is as high as 88.81%. These results could be used as the basis for subsequent preheating and reduction process.
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