The Application Of Computer Digital Image Processing Technology In The Online Mineral Particle Size Measurement

Particle size is an important quality index of mineral processing, chemicalindustry, medicine industry and metallurgy, powder engineering, etc. All the material and products in all these fields are made up of particles, and the particle size and distribution is one of their most important characters. It exerts significant influence on technical performance of products and plays key role in practical application At present the routine methods, for example, sedimentation and fractionation technique are chiefly adopted in measurement of particle size. There are some disadvantages in these routine methods, for example, they takes many steps and costs much time, and theaccuracy of results is efected greatly by subjective factors of human inspectors. The online measurement technology of particle size's using computer picture can overcome the shortage of routine methods, and so it is one of the most efective methods for measurement of particle size. In this paper, the contrast of original image is enhanced by nonlinear transformation based on the characteristics of grain image; After comparing several methods of threshold segmentation and analyzing their performance and applicability on grain image,the adaptive threshold segmentation based on gradient image is presented; The noise of binary image is reduced with morphological filter, the hollow in binary image is filled in and a recognition algorithm is designed to remove agglomerate particle; on the basis of mathematical morphology two methods are adopted to segment agglomerate grains that are not agglomerated tightly; The parameters of size and shape, perimeter, area, diameter, complexhty, longest feret diameter, shortest feret diameter etc, are extracted. This technique is applied in measurement of mineral particle size. Experiments proved that this method of mineral particle measurement could determine grain distribution clearly and directly. The device can detect particle size widely ranged and the result of inspection is speedy and stable, and is useful to mineral processing.