Destoning Machine Manufacturers for Food

Destoning machines — how they separate stones from food products

Destoning machines (stone separators) remove stones, gravel, glass fragments, and other dense, heavy foreign material from a product stream of grain, seeds, pulses, spices, or other granular food material. The operating principle exploits the density difference between the food product and the stone: stones are denser (2.0–2.7 g/cm³) than most food grain material (0.7–1.4 g/cm³). The main destoning technologies are: dry gravity destoners (vibrating inclined table with upward airflow — the product stratifies into a lower dense layer and an upper light layer; the table vibration moves the dense stone layer upward to the heavy discharge and the light grain layer downward to the product discharge; standard for grain, seed, and spice destoning); wet destoners (the product is floated in water — stones sink and grain floats; used for root vegetable and tuber cleaning, not for dried grain and spice); and spiral stone separators (centrifugal action separates dense material in a spiral flow of water or air). Destoners must be sized for the required product throughput — the effective capacity depends on the product density difference and the throughput per unit of table area.