机械力活化硫化矿石的吸附孔分形表征

Fractal characterization of adsorption-pore for mechanically activated sulfide ores

为了揭示机械力活化影响硫化矿石吸附孔隙的分形特征,采集国内某一典型高硫矿山矿样,在六种不同条件下进行机械球磨。联合扫描电子显微镜和低温氮吸附试验,测量各个矿样的孔容,比表面积和孔径分布,深入分析其孔隙形态特征。运用FHH模型计算出各个矿样的分形维数,揭示了活化矿样的分形维数与孔隙参数、气体吸附能力两两之间的关系。结果表明:不同机械力活化条件下硫化矿样对气体的吸附主要集中在2~30 nm的介孔上;不同料球比活化条件下,硫化矿样比表面积的大小顺序依次为:a(1∶3)<b(1∶6)<c(1∶10);不同球磨速率活化条件下,其大小顺序依次为:d(300 r/min)<e(400 r/min)<f(500 r/min);硫化矿样分形维数的大小顺序与其比表面积一致,但平均孔径却与之相反。机械力活化增大了硫化矿样的分形维数,提高其对氧气的吸附能力,从而有助于氧化自燃化学反应的发生。

In order to uncover the fractal characteristics of adsorption-pores of mechanically activated sulfide ores,a representative sample collected from a typical sulfur-rich mine was activated into 6 groups under different mechanical activation conditions.Both scanning electron microscopy（SEM） and low-temperature nitrogen gas adsorption（LT-N2GA） were performed to gain insight into the nature of the pore morphology,including the pore volume,specific surface area（SSA）,and pore size distribution（PSD）.The FHH（Frenkel-Halsey-Hill） model was performed to calculate their fractal dimensions.The relationships of fractal dimension—pore-structure parameters and fractal dimension—adsorptive capacity were further analyzed.The results show that gas adsorption of sulfide ores under mechanical activation mainly occurs in the mesopores varying from 2 to 30 nm.The order of SSA for samples under different sample to ball ratios is：a（1∶ 3） 〈b（1∶ 6）〈 c（1∶ 10）; and that of samples under different mill speeds is∶ d（300r/min） 〈e（400r/min）〈 f（500r/min）.The order of samples＇ fractal dimension is consistent with that of SSA,but average pore diameter is the exact opposite of that.Mechanical activation increases the fractal dimension of sulfide ore and improves the ability of oxygen adsorption,thus contributing to oxidation and spontaneous combustion.