Advances in the characterization of industrial minerals
The use of minerals by man is as old as the human race. In fact the advancement of human civilization has been intimately associated with the exploitation of raw materials. It is not by chance that the distinction of the main historical eras is based on the type of raw materials used. Hence the passage from the Paleolithic and Neolithic Age to the Bronze Age is characterized by the introduction of basic metals, mainly copper, zinc and tin, to human activities and the Iron Age was marked by the introduction of iron. Since then the use of metals has increased and culminated in the industrial revolution in the mid-eighteenth century which marked the onset of the industrial age in the western world. However, during the past 50 years, although metals were equally important to western economies as they had been previously, the amount of metals extracted annually in western countries has decreased significantly and metal mining activity shifted mainly to third world countries (in Africa, South America, Asia) and Australia, due to economic and environmental constraints. At the same time the role of industrial minerals has become increasingly important for the western economies and today, in developed EU countries, the production of industrial minerals has surpassed by far the production of metals. In some EU countries, metal mining activities have stopped completely. The importance of industrial minerals is expected to increase further in the future.
Image Analysis for Advanced Characterization of Industrial Minerals and Geomaterials
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Published:January 01, 2010
Abstract
This chapter is dedicated to the science of extracting quantitative information from digital images representing minerals and rocks. Because of the extraordinary complexity of natural textures, but also due to the wide diversity of mineral species, such analysis is still regularly performed by geologists using manual point-counting methods and basic stereological principles. If one aims to automate the process, it is essential to realise that images have to be acquired wherein individual minerals are contrasted as much as possible. This depends heavily on the quality of the imaging instrument and the attention dedicated to sample preparation.
After reviewing a range of modern mineral-imaging modes using electrons, X-rays, photons and even nanosized probes, the chapter focuses on the tools and techniques most commonly used to archive and process digital images. Special emphasis is given to image segmentation techniques that allow the user to classify pixels and map homogeneous domains that might correspond to specific minerals or single crystals.
The image analysis part sensu stricto addresses the quantitative description of mineral abundance before suggesting different techniques to analyse size and shape distributions of particles and grains. A brief introduction to network description is also given with special attention paid to the powerful concept of intercepts.
Finally, images are presented as support for physical simulations that bring new insight to behaviour of geomaterials with respect to processes such as diffusion and percolation.
