udsiftning

Udsiftning, often translated as screening or sieving in English, is a separation operation in which solid material is divided into fractions by passing it through a screening surface or by using other size-selective media. The process relies on particle size differences and is typically aided by mechanical agitation, gravity, or flow. Udsiftning can be performed dry or with liquids (wet screening) and is commonly used after crushing or grinding to separate coarse from fine material.

Applications span many industries. In mining and mineral processing, it removes fines and helps separate ore from gangue. In agriculture and seed processing, it cleans grains and seeds by removing small debris. Construction and recycling industries use udsiftning to sort aggregates or mixed waste by size. Water and wastewater treatment apply screening to remove suspended solids and protect downstream equipment.

Techniques and equipment vary. Screens may be vibrating, circular, banana-shaped, or trommel-type, with aperture sizes chosen to achieve the desired separation. Dry screening relies on minimal moisture, while wet screening uses liquids to reduce particle sticking and improve throughput. Screen media include wire mesh, polyurethane, and rubber panels. Throughput and efficiency depend on feed rate, particle size distribution, moisture, and screen motion, as well as pre-treatment steps such as washing or de-dusting.

Performance considerations include screening efficiency, cut size, and capacity. Undersize and oversize fractions quantify performance, and regular maintenance is important to prevent clogging and wear. The term reflects a Danish-origin concept and is widely used across engineering, mining, agriculture, and environmental contexts.