Method for drying, especially waste material, such as shrimp or crayfish shell, fish offal, etc.

A method for drying moist starting material lumps, having a water content of up to 85%, comprising:

• a) introducing the material into a swirl drying chamber in which it is accelerated in an air current composed of a multitude of turbulent air currents of sufficiently high air velocity, so that water is evaporated and the material lumps continuously collide with each other, and disintegrate into smaller pieces to expose new surfaces of rupture until a final product is obtained having a particle size of 10-500 .mu.m and a maximum residual water content below 10%;
• b) passing air into the drying chamber to form the multitude of currents, which air has a temperature of between about 350.degree. and 450.degree. C., the choice of the exact temperature depending at least partly on inlet temperature of the starting material and at least partly on disintegration rate of material, said air being introduced in an amount adjusted according to the amount of starting material introduced per time unit, so that free water in the material immediately escapes from the exposed surfaces of rupture by evaporation, said evaporation contributing to the cooling of the final product, thereby protecting and preserving the aroma and flavor components as well as the proteins and vitamins;
• and
• c) retaining the material in the drying chamber by exerting a counter-pressure to regulate the air throughput until the predetermined particle size and water content of the product have been established.