SWeRF—A Method for Estimating the Relevant Fine Particle Fraction in Bulk Materials for Classification and Labelling Purposes

Ingeborg Pensis,Frank Luetzenkirchen,Bernd Friede

doi:10.1093/annhyg/met076

Abstract

In accordance with the European regulation for classification, labelling and packaging of substances and mixtures (CLP) as well as the criteria as set out in the Globally Harmonized System (GHS), fine fraction of crystalline silica (CS) has been classified as a specific target organ toxicity, the specific organ in this case being the lung. Generic cut-off values for products containing a fine fraction of CS trigger the need for a method for the quantification of the fine fraction of CS in bulk materials. This article describes the so-called SWeRF method, the size-weighted relevant fine fraction. The SWeRF method combines the particle size distribution of a powder with probability factors from the EN 481 standard and allows the relevant fine fraction of a material to be calculated. The SWeRF method has been validated with a number of industrial minerals. This will enable manufacturers and blenders to apply the CLP and GHS criteria for the classification of mineral products containing RCS a fine fraction of CS.

Highlights

The inorganic chemical compound silicon dioxide, known as silica, exists in many different forms
To prevent the sample from flocculating or coagulating, addition of a suitable dispersant, such as Quartz samples The size-weighted relevant fine fraction (SWeRF) of eight commercial quartz products, with grain sizes ranging from coarse sand to fine flour, supplied by Quarzwerke and SCR-Sibelco, was determined both by calculation from the particle size distribution (PSD) and gravimetrically by the sedimentation technique
In order to investigate whether the SWeRFCS of a quartz-containing mineral blend can be determined, a quartz-free pure barite sample (BaSO4) from Ankerpoort NV was spiked with different amounts of quartz flour

Summary

Introduction

The inorganic chemical compound silicon dioxide, known as silica, exists in many different forms. The SWeRF method combines the particle size distribution of a powder with probability factors from the EN 481 standard and allows the relevant fine fraction of a material to be calculated. The Metrology Working Group of the European Industrial Minerals Association, IMA-Europe, has developed the principle of the size-weighted relevant fine fraction (SWeRF) for estimating the potential respirable fraction in bulk materials for classification and labelling purposes.

Results

Conclusion