Application of an operational method for control and management based on computer physical and chemical modelling of alumina charge sintering

The present study is aimed at the development of a method for computer control and management of mineral formation and emissions of hazardous compounds during processing of nepheline ore by sintering in tubular rotary kilns. Technological, mathematical and mineralogical research approaches taken when developing the method included physical and chemical modelling using the Selector software package. In accordance with the technological stages of obtaining sintered mass (drying, dehydration, decarbonisation, reflow, sintering and cooling), the developed physical and chemical model is conventionally divided into six thermodynamic tanks (furnace zones) with simulation of mutual mass and energy transfer. Coordination of the simulation results with the production and statistical data of RUSAL Achinsk JSC was carried out by analysing a furnace operation with a processing volume of 120 tons of charge per hour. During the processing of nepheline charge with the production of alumina and sodium products (having a standard analysis methodical accuracy of 1-5%), the deviation of production indices for the extraction of Al₂O₃ from the predicted results was shown to comprise 0.1-0.6 and 1.5-2.1% for physical and chemical modelling and thermophysical field controlling, respectively. The applied sintering process modelling using the Selector software package provides for a significant increase in the degree of control and management of the raw material processing cycle. The proposed method of thermodynamic analysis is shown to provide high-precision control of the mineral formation processes in technological zones of the alumina charge sintering furnace and to guarantee a deviation of Al₂O₃ content in the sintering mass from the predicted data of no more than 0.1-0.6%. The 85.8% rate of Al₂O₃ extraction calculated using the physical and chemical modelling corresponds closely with the average value of 85.7% according to production data.

alumina production, sintering, physico-chemical modelling, nepheline and limestone charge, minimization of Gibbs free energy, sodium product