MINERALOGICAL CHARACTERISTICS AND APPLICATIONS OF VERMICULITE FROM SEVEN MAJOR MINES IN CHINA

摘要

We studied mineralogical characteristics of the vermiculite samples from seven mines in China. We found three types of interstratified structures in the investigated samples: 1:1 regular interstratified structure, segregated interstratified structure, and random interstratified structure. The vermiculite samples from six mines are mainly composed of phlogopite-vermiculite interstratified minerals, and the samples from the other mine are composed of chlorite-vermiculite interstratified mineral. The samples with phlogopite-vermiculite structure have high contents of K_2O, TiO_2 and Na_2O. The samples with chlorite-vermiculite structure have the highest contents of MgO and Al_2O_3. The cation exchange capacity of the samples is 17.3-99.0 mmol/100g.The exchangeable cations of phlogopite-vermiculite samples from Weili Mine mainly include Na~+ and Ca~(2+), while those of phlogopite-vermiculite samples from Tongguan Mine mainly include Mg~(2+) and Ca~(2+). The thermal expansion ratio of the samples is between 9 and 32. The exfoliated vermiculite products from Weili Mine have the best mechanical strength.