Mineral Fibers: Chemical, Physicochemical, and Biological Properties

This chapter discusses the chemical, physicochemical, and biological properties of mineral fibers. Among the most important occupational air pollutants are particles of coal, quartz, and fibers of asbestos, which are inhaled by miners and exposed industrial workers. Mineralogically, asbestos is divided into two classes: serpentine and amphibole. The former is a sheet silicate, whereas the latter is built up of double chains of tetrahedra. Chrysotile is the principal asbestos member of the serpentine family, whereas all other asbestos minerals belong to the amphibole group. Chrysotile asbestos is usually worked relatively near the surface by open-cast pit methods. Once the overburden has been cleared, explosives are used to release large tonnages of rock and fiber, the latter accounting for only a few percent of the parent rock. Crude asbestos, together with associated mother rock is conveyed to sorting stations, where waste rock is rejected and the ore undergoes a series of crushing and grinding operations. Fiber bundles of widely different lengths are inevitably mixed together. Subsequent screening results in a rough separation into grades but such screening is too imperfect to remove all the shorter fibers from the longer grades and even the lower grades contain a few long fibers. © 1975, Elsevier Inc. All right reserved.