粒度对铝土矿烧结性能的影响

Effects of particle size on sintering properties of bauxite

以山西阳泉铝土矿为原料，分别细磨至粒度为0．147～0．075、0．075～0．044和≤0．044 mm的粉体，加结合剂混匀后压制成坯，干燥后在电炉中分别于1550、1580、1600、1650和1700℃保温3 h煅烧。研究了不同粒度矾土矿的烧结情况，并用XRD和SEM对烧后试样的相组成和显微结构进行了研究。结果表明：Al2 O3含量为84％（w）的Ⅰ等铝土矿细磨至0．075～0．044 mm，1600℃煅烧3 h后可达到最佳烧结状态。刚玉晶体发育完整，晶粒大部分呈长柱状，晶粒间结合紧密，杂质均匀分布在晶界的玻璃相中。研磨至0．044 mm以下的矾土，煅烧后晶粒内部形成大量封闭气孔，导致体积密度下降。

Bauxite from Yangquan,Shanxi Province was milled into powders with different particle sizes （0.147-0.075,0.075 -0.044,and ≤0.044 mm）,added with binder,mixed well,pressed into green speci-mens and calcined at 1 550,1 580,1 600,1 650,and 1 700 ℃for 3 h in an electric furnace,respectively.The sintering property of bauxite with different particle sizes was studied.The crystalline phases and micro-structures of the fired specimens were characterized by XRD and SEM.The results indicate that the opti-mum sintering of the bauxite can be achieved at the particle sizes of 0.075 -0.044 mm after calcining at 1 600 ℃ for 3 h;the corundum crystals fully develop,and most are long columnar;the grains combine closely and the impurities distribute evenly in the glass phase of the grain boundary;the bauxite with size≤0.044 mm has many pores in the grains after calcining and leads to low bulk density.