黄河砒砂岩中蒙脱石的基本特征

Characters of Montmorillonite of Pisha Sandstone

黄河砒砂岩是一种复杂的松散岩石,其含有黏土矿物蒙脱石是砒砂岩遇水膨胀溃散的主因,分析蒙脱石基本特性对于认识砒砂岩易膨胀溃散的机理非常必要。采用湿法提纯,从砒砂岩中分离出蒙脱石,通过XRF、XRD、ICP、Zeta电位、TG/DTG测试,对蒙脱石的类型、吸蓝量、层间离子交换容量及分子结构式等进行了分析。试验结果表明:砒砂岩中的蒙脱石为钙基蒙脱石;白色和红色砒砂岩中蒙脱石的吸蓝量分别为32.72、28.21 g/100 g,膨胀容分别为5.4、5.1 m L/g,离子交换容量(CEC)分别为112.72、104.91 mmol/100 g,Zeta电位分别为-24.5、-22.9 m V;红色、白色砒砂岩中蒙脱石的分子结构差别不大。

Pisha sandstone is a complex of mudstone and siltstone. The clay mineral content montmorillonite is the main reason that caused the collapse of Pisha sandstone when soaking in water. It is very necessary to study the characters of montmorillonite of Pisha sandstone for understanding the collapsibility of Pisha sandstone. The montmorillonite was isolated from Pisha sandstone, and the type of montmorillonite, Methylene blue adsorbed, CEC and molecular structural was tested by XRF, XRD, ICP, Zeta potential and TG/DTG in this study. The results of white and red Pisha sandstone show that the montmorillonite from Pisha sandstone is attributed to Ca-montmorillonite, and the values of Methylene blue adsorbed are 32.72 g/100 g （white Pisha） and 28.21 g/100 g （red Pisha）, the volumes of expansion are 5.4 mL/g （white Pisha） and 5.1 mL/g （red Pisha）, the CECs are 112.72 mmol/100 g （white Pisha） and 104.91 mmol/100 g （red Pisha）, the Zetas potential are -24.5 mV （white Pisha ） and -22.9 mV （red Pisha ）, respectively. The difference of molecular structure of montmorillonite between white and red Pisha is very little.