Hammer Mill Crushers

Hammer mill or Hammermill crushers are impact type crushers and operate on a similar principle to the Horizontal Shaft Impact crusher (HSI). Hammermills consist of a horizontal rotating shaft to which hinged or fixed heavy metal hammers are attached. The shaft is placed inside a circular chamber which is lined with adjustable and replaceable grinding walls. The material is fed into the top of the chamber where it impacts the rotating hammers and is reduced in size. The hammers throw the material outward against the hard wearing liner material. In this manner the material is reduced by repeated impact against the hammers and the grinding surface until the desired material size is reached and it drops through a sizing device. Material sizing is achieved by hammer rotational speed and by adjustment of the clearance between the grinding surface and hammers. Some designs allow the the rotational direction of the hammers to be reversed, so they experience even wear and optimize their lifespan. The hammers are wearing parts and can be eventually replaced.

Hammermills offer high throughput primary and secondary crushing. Hinged hammer designs are often used in size reduction of coal, coke, gypsum, limestone or other minerals of soft to medium-hard consistency. Fixed hammer designs are good for ore or medium hard rock. Good choice where high reduction ratios are required. Capital cost per ton of capacity is low, however higher rotation speeds and wear will result in increased operating and maintenance compared to other types of primary crushers.

- Sandvik Mining and Construction Images.