Numerical and Experimental Study of Packed Bed Heat Transfer on the Preheating of Manganese Ore with Air up to 600 °C

Abstract

This work studies heat transport in the fluid–solid interface of a packed bed to demonstrate the feasibility of preheating lumpy manganese ores to 600 °C with air at 750 °C. Preheated manganese ores aim to reduce furnace energy consumption during smelting in submerged arc furnaces to produce manganese ferroalloys. The preheating process was experimentally studied in a pilot-scale shaft-type column. The air was heated to 750 °C and used as a heat transfer fluid to heat a packed bed of manganese ore from room temperature to 600 °C. A one-dimensional three-phase (manganese ore, air, and the column wall) numerical model was developed to simulate the preheating process. The energy balance of the three phases was carried across a finite volume using the volume averaging technique. Numerical schemes were applied, and non-dimensional parameters were introduced before applying numerical techniques to solve the systems of linear equations. Python NumPy and SciPy modules were used for the computation of the packed bed temperature fields. Temperature data from the preheating tests were used for model validation. The model prediction of the transfer process agreed with experimental results to least square errors of less than 25 °C. Data from experimental measurements confirmed the feasibility of using air as the transfer fluid in the preheating of manganese ore. Detailed temperature field data generated from the model can be used for the sizing of manganese ore preheating units and the implementation of control protocols for the preheating process.