Agglomerointi

Agglomerointi, or agglomeration, is the process by which fine particles are gathered into larger, cohesive aggregates called agglomerates or granules. It is widely used in material processing to improve flowability, reduce dust, enhance handling, and prepare materials for subsequent operations such as compaction, smelting, or dissolution.

Mechanisms include wet agglomeration, where a liquid binder creates capillary bridges between particles; and dry agglomeration, which relies on compression, pressure-induced bonding, or solid bridges. Interparticle forces such as van der Waals, electrostatic attraction, capillary force, and, at elevated temperatures, sintering play roles. The resulting agglomerates are typically porous and have a broad size distribution.

Two main categories:

- Dry agglomeration (briquetting, compaction) forms larger, solid pieces without added liquids; common in coal, metal fines, and some catalysts.

- Wet agglomeration (granulation, pelletizing) uses binders to form granules or pellets; common in fertilizers, cement and ceramic powders, iron-ore pellet production, and pharmaceutical granulation.

Processes and equipment: disc pelletizers (pan granulators), rotary drum granulators, agglomerating drums, and briquetting presses. Binder selection, moisture control, and process temperature influence strength and porosity.

Applications and benefits: improved handling, reduced dust, enhanced flow, slower dissolution or controlled release in some products. In mining, agglomeration improves heap-leaching and pellet quality; in construction materials, it aids proper curing and strength development.

A separate use of the term in geography: agglomeration describes the clustering of population, firms, and activities in a metropolitan area, leading to agglomeration economies.