烧结混合料适宜制粒水分的预测

水分是影响铁矿混合料制粒、烧结的重要因素.研究结果表明,随着制粒水分增加,制粒后混合料中细粒级颗粒含量减少,平均粒径增大,透气性迅速提高但随后增幅放缓或有所下降.透气性增幅达到缓和的水分点可作为适宜制粒水分的判据,且烧结速度在适宜制粒水分时达到最大值.通过筛分分级的方法将混合料分成-0.5 mm的黏附粉和+0.5 mm的核颗粒,并检测核颗粒的比例X_+0.5,通过饱和吸水法检测黏附粉的最大毛细水量W_p,通过离心法检测核颗粒的持水量W_c,另外根据数学模型W=X_+0.5·W_c+0.72(1-X_+0.5)·Wp预测适宜的制粒水分.适宜制粒水分绝对误差为±0.3%的情况下预测准确率可达93.3%,能满足混合料适宜制粒水分预测对精度的要求.

Prediction of suitable water content on the granulation of a sintering mixture

Water content is an important factor which affects the granulation of a mixture and sintering.Research results show that with the water content for granulation increasing,the proportion of fine particles reduces in the granulated mixture,the mean size increases,and the permeability rapidly improves firstly,but then mildly changes even goes down.The point of water content at which the permeability grows smoothly can be used as a criterion of suitable values for granulation,and it is found that the sintering speed reaches maximum at the suitable water content for granulation.The mixture can be divided into two parts by the mathematical method of sieving,one is-0.5 mm as adhering fine powders,the other is +0.5 mm as nucleus particles,and the ratio of nucleus particles X_+0.5 was measured.The suitable water content can be predicted based on the model of W=X_+0.5 W_c+0.72(1-X_+0.5)W_p,in which the maximum capillary water content of adhering fine powders W_p is measured by a saturated water absorption method and the preserved water content of nucleus particles W_c is measured by a centrifugal method.The accuracy of prediction reaches 93.3% when the absolute error of the suitable water content for granulation is ±0.3%,which can satisfy the requirement of predicting accuracy.