Since the grinding sand using book each time. The sand is coarse and resolution of volume, more or less, depending on the time of grinding. Screening will take part in a ball. mill , which is based on the size of each class.
Due to the grinding sand by the library in each time. Roughness and resolution of sand will be split in more or less depending on the time of grinding. The separation size is used ball mill , which will depend on the size of each layer.