Analysis and optimization of process parameters affecting classification performances indices of the turbo air classifier

Classification performance indices of a turbo air classifier mainly include cut size, classification precision, and Newton's classification efficiency, which would be effected by the process parameters including air inlet velocity, rotor cage's rotary speed and feeding speed. Orthogonal experiment method was used to analyze the influence of process parameters on the classification performance indices according to quartz sand powder classification experimental data as well as the calcium carbonate classification experimental data. Through range analysis of the orthogonal experiments for quartz sand and calcium carbonate, it is found that air inlet velocity and rotor cage's rotary speed play an important role on classification performance indices including classification accuracy, cut size and its corresponding Newton's classification efficiency. Feeding speed has slight impact on these performance indices. The best optimized combination of the process parameters for quartz sand was: when air inlet velocity was 20 m · s^–1, rotor cage rotary speed was 900 min^–1 and feeding speed was 56.69 kg · h^–1, the high Newton's classification efficiency and classification accuracy could be obtained and the corresponding values were 73% and 0.66. This best optimized combination was among the 9 group orthogonal experiments for quartz sand. The best optimized combination of the process parameters for calcium carbonate was: air inlet velocity was 14 m · s^–1, rotor cage rotary speed was 1200 min^–1 and feeding speed was 120 kg · h^–1. However this best optimized combination wasn't among the 9 group orthogonal experiments for calcium carbonate. The evaluated value of the Newton's classification efficiency of cut size can be obtained, which was 73%. In order to verify this evaluated value, the classification experiment for calcium carbonate with this best optimized combination of process parameters was carried out and experimental value of Newton's classification efficiency was 75%, which was close to the evaluated value. Through orthogonal experiment analysis, the influence law of process parameters on classification performances indices of the turbo air classifier can be acquired and the optimized combination of process parameters can be obtained. It paves the way of the development of the turbo air classifier.