[The problem of determining asbestos in bulk materials: a study of the effect of grinding on the diffractometric response of the chrysotile content in an asbestos cement sample].

To determine the asbestos content in a bulk sample by X-ray diffractometry, the sample must be previously comminuted until an adequate granulometry is reached. However, this treatment can produce a decrease in fibre crystallinity which, in turn, causes an attenuation of the diffractometric response of asbestos. The authors studied a "wet" comminution method that was tested on an asbestos-cement sample containing chrysotile. This procedure made it possible to limit the attenuation of the diffractometric response of chrysotile to reasonable values (about 20%). Moreover, the study of the comminution kinetics revealed a time interval during which both fibre granulometry and diffractometric response tend to reach a plateau value. In this interval, the comminution time is not a critical factor with respect to the diffractometric behaviour of chrysotile. Therefore, this interval offers favourable conditions for preparing bulk samples to be submitted to X-ray diffraction.