A Proposed Procedure for Identifying the Predominant Heat Transfer Modes Along the Length of Large Nickel Laterite Ore Rotary Kiln: Experimental Validation in an Industrial Process

Abstract

Nickel is essential in many consumer, industrial, military, transport, aerospace, marine, and architectural products due to its outstanding physical and chemical properties. This work focuses on the calcination and pre-reduction of laterite nickel ore to produce ferronickel. Ferronickel is an alloy containing nickel (about 30% wt.) and iron used for manufacturing stainless steel. Calcination and pre-reduction entail removing chemically bonded water from partially dried ore and removing oxygen from mineral oxides in the calcine. Here we combine a proprietary database with operation data of two rotary kilns and model predictions of Mean Residence Time, shell losses, intraparticle evaporation, and intraparticle temperature distribution. The kilns feature notable differences in length, inclination angle, excess air, but the predicted Mean Residence Times are similar. A fitted profile of experimental solids bed temperature represented particles surface temperature. The model considered slab-like mineral particles with surface-to-center distances of 13, 25, and 38 mm. Results show notable differences in the drying zone length and average surface-to-center temperature differences. Surface-to-center distances higher than 25 mm result in average surface-to-center temperature differences higher than 80°C. The following steps are improvements in the particle model and its coupling with the gas and wall temperature profiles.