Because the fibers are usually the outer shell of the vegetable material and hard to be milled, the wear to the grinding machine is extremely high. The machine parts are worn away by silica content in the fiber. Because of this, the wear-protection class should be higher than the Mohs’ scale.
The complex structure of roughage coupled with even low mineral substances is difficult to grind, results in a high-energy requirement for ultrafine grinding. The greater the fineness is; the higher the required grinding energy is. Subjecting the roughage to a thermal treatment step, a positive effect to reduce the required energy by about 20%. Applications for roughage are mainly in the food industry but also in other industries (packing industry, insulating material for buildings). Roughage is used in the food industry in whole-grain products, as “additives” in drinks and in snacks, etc. Besides the fine grinding, which forms the main point of emphasis in terms of altering the sensory and physical properties of the product, separation of certain constituents from the roughage provides a further possibilities of fulfilling customer-specific requirements.