Optimization of the Production of Quicklime by Calcination in Rotary Kilns
It well known that the operational conditions of rotary kilns affect strongly the quality of quicklime produced. This work presents a study about parametric optimization of rotary kilns for quicklime production (CaO) from thermal decomposition of calcite limestone (CaCO3). The approach used is based on the technique of design of experiments (DOE) to identify the most significant variables which affect the quality of oxide and, in addition, to determine better conditions of production. An experimental setup in laboratory scale was build in order to carry out the experiments. Calcination temperature, calcination time, rotation speed, particle mean diameter, heat flow and air flow rate were evaluate using a fractional factorial design. The parametric optimization shows that the raise of time and temperature of calcinations produces an increase of free CaO terms. However this operation is not useful due to sintering process observed in the BET surface area results. A correlation between quicklime reactivity and specific surface area could be established, in way that reactive quicklimes presented bigger areas. Finally, it was possible to determine the best conditions of quicklime production and to estimate a quadratic model by using a central composite design and a like surface response model. It was found that the best region of operation is about 900oC and 45 minutes of calcination time.
Lucio Salgado and Francisco Ambrozio Filho
B. D. Soares et al., "Optimization of the Production of Quicklime by Calcination in Rotary Kilns", Materials Science Forum, Vols. 591-593, pp. 811-815, 2008