Analysis of Asbestos in Bulk Materials by X-Ray Diffraction: Influence of Grinding Methods on the Result

Abstract

The grinding method for sample preparation affects the results of X-ray diffraction analysis of minerals, mainly the soft and inelastic components of raw materials and synthetic matrices. This fact is determined by a "disturbance" of crystal order in the surface layer of particles and is more pronounced when a fine comminution is performed and when a high shearing stress is applied in grinding. This effect is remarkable on asbestos minerals. Subsequent to some information on the development of the science of "mechanochemistry", this paper reports the results of several tests on single, binary and polygenic materials containing chrysotile and crocidolite under different grinding conditions (type of mi11 and grinding time). The aim of the research is to give suggestions about a sample preparation methodology for XRD quantitative determination of asbestos in bulk materials, suitable for obtaining more accurate results.

Use of X-ray Powder Diffraction for Determining Low Levels of Chrysotile Asbestos in Gypsum-Based Bulk Materials: Sample Preparation

“…(5) Elimination of Crystallite Size Effects. The effects of ball milling on fiber morphology and crystallinity have been discussed in several publications. − The decrease of the (002) chrysotile peak has been attributed to the decrease of crystallinity. In order to find a milling method that allows reduction of fiber morphology while keeping the (002) peak intensity unchanged within a reasonable length of time, three mill methods (ball milling, Waring blender milling, ultrasonic milling) were investigated.…”

A Systematic Study of the Cryogenic Milling of Chrysotile Asbestos

“…Many different types of instrumental setups have been used to systematically investigate the effect of mechanical action on chrysotile. These include dry milling in planetary ball mills [29][30][31][32], milling in vibration ball mills in dry conditions as well as in the presence of hydrocarbons or water [33][34][35], dry milling in a vibration disc mill [36], and rotary mill (also called ring and puck mill or shutter box) [37]. Generally speaking, size reduction was accompanied by plastic deformation of the chrysotile structure and prolonged mechanical action eventually led to complete amorphization.…”