大型一次磨机的衬板设计,材料及操作实践

根据自磨机和半自磨机二十多年来的实践经验发展的准则,可明显提高磨机衬板的寿命和设备利用率。本文对自磨机和半自磨机衬板的功能、性能判据、耐磨材料和维修方法进行了评述,并对可能导致衬板加速磨损和断裂的操作实践进行了讨论。     

Reflectance and albedo differences between wet and dry surfaces

It is commonly observed that natural multiple-scattering media such as sand and soils become noticeably darker when wet. The primary reason for this is that changing the medium surrounding the particles from air to water decreases their relative refractive index, hence increases the average degree of forwardness of scattering as determined by the asymmetry parameter (mean cosine of the scattering angle). As a consequence, incident photons have to be scattered more times before reemerging from the medium and are, therefore, exposed to a greater probability of being absorbed. A simple theory incorporating this idea yields results that are in reasonable agreement with the few measurements available in the literature, although there are differences. Our measurements of the reflectance of sand wetted with various liquids are in reasonably good agreement with the simple theory. We suggest that the difference between reflectances of wet and dry surfaces may have implications for remote sensing.