Converter sludge drying in rotating drum using hot steel balls

Abstract

Converter sludge is a by-product of converter steelmaking and a secondary resource of recovery; however, it needs to be dried before recovery. Obtaining the expected results using traditional sludge drying technologies is difficult due to the special properties of converter sludge. In this research, we proposed a new rotating-drum-drying technology using hot steel balls. Steel balls are heated by the waste heat of metallurgical slag. This technology has the advantages of low cost, high efficiency and thorough drying, and can overcome the shortcomings of traditional technologies. This research explored the converter sludge drying in a drum through experiments. The effect of four operating parameters on the drying process was investigated, and the suitable model for the drying process was discussed. The operating parameters include sludge treatment mass (3.0/4.0/5.0/6.7/9.0 kg), steel ball (initial) temperature (300/500 °C), steel ball diameter (20/30/40 mm) and drum rotating speed (1/3/5/7 rpm). Results show that this proposed technology is feasible and efficient. Sludge drying can be accelerated by appropriately reducing the sludge treatment mass, increasing the steel ball temperature, increasing the steel ball diameter, and selecting an appropriate drum rotating speed. The Weibull model can better predict the drying process by comparing multiple models. The operating parameters have obvious relationships with the fitting parameters of the Weibull model.