Abstract
In recent years, long fiber sepiolite from China has been used as an asbestos substitute in Japan. It is known that the long fiber sepiolite from China somtimes contain tremolite as an impurities, and our previous report described a method of quantitative analysis of tremolite in sepiolite sample by XRD. However, in order to know the content of only fibrous tremolite which is attributed to asbestos, it is necessary to discriminate the form of tremolite particles. In this research, forms of tremolite particles contained in long fiber sepiolite from China were observed under a three dimensional (3D) particle measurement laser microscope (3D-LM) and a polarized microscope (PLM), and each content of fibrous and non-fibrous particles could be measured in wt%. By this measurement, a constant relationship between width (x) and thickness (z) of tremolite particle was found as z=0.46x. This empirical equation was examined from the morphological view of tremolite, and presumed to be held good in general. By this equation, the weight ratio of the fibrous and non-fibrous particles of tremolite can be calculated. It was evaluated that fibrous tremolite in the total particles of tremolite contained was about 9 wt% in the long fiber sepiolite sample from China. It is concluded that the content of fibrous tremolite in a sepiolite sample can be seen in wt% based on the content of the total tremolite in the sepiolite sample measured by the XRD and the ratio of fibrous tremolite in total tremolite particles measured by 3D-LM and PLM.
