Effect of aluminium sulfate on carbothermal reduction of phosphorite in a fluidized bed

Aluminium sulfate was combined with the raw material pretreatment in a fluidized-bed reactor to reduce the phosphorite by coal, so as to improve the separation of P2 from phosphorite. The optimum reaction conditions for phosphorite reduction in a fluidized bed is found to be 1523 K, 40 min, Si/Ca mole ratio of 2, carbon excess coefficient of 1.6, and nitrogen flow of 0.11 m & sdot;s(-1). Sensitivity analysis reveals that the five influencing factors on the conversion ratio of phosphorite, in descending order of importance, are the reaction temperature, the nitrogen flow, the reaction time, and the excess of carbon and the mole ratio of Si/Ca. The influence of adding aluminium sulfate on the reaction system and pretreating the raw material was investigated. The results show that by speeding up defluorination while decreasing the activation energy, adding aluminium sulfate and pretreatment could improve the conversion ratio of phosphorite by about 10 %.