Metso is the industry leader in stirred milling


The Metso stirred media detritor (SMD) has proven effective in producing fine and ultra fine product size for a wide range of metalliferous feeds. Feed size is typically 80% passing 100 µm and finer, but can handle coarser in various applications.

A wide range of feed slurry solids concentrations can be accommodated, typically in a range of 30-60% w/w. 

The normal operating range is 20-100 kWhr/ton, which meets the majority of metalliferous fine and ultra fine grinding requirements. 

SMDs are currently available with an installed power up to 1100 kW.


  • Low installation cost
  • VFD Compatible
  • Very small footprint
  • Low Operating Cost
  • High Availability
  • Simple Foundations
  • Modular design for faster installation
  • Maintenance friendly – All wear parts can be changed through access doors
  • Open or closed circuit operation
  • Mechanically simple design
  • Competitive capital cost
  • Use of low cost, ceramic, natural silica sand or pebble media
  • No steel contamination of product
  • Capacity to operate continuously at full load power draw
  • Low rotational impeller speed with shallow charge depth providing reduced abrasion of impeller and body liner coverings


  • Low Noise – Typically <85 db
  • Great Operating Safety – All Moving parts are enclosed

Process overview

The SMD utilizes the rotational energy of the impeller arms to impart a high-energy motion to the media/ slurry mixture inside the mill. This results in particle-to-particle shear and compressive forces which produce the desired grinding mechanism for fine grinding. 

The vertical arrangement allows the drive train to be entirely supported by the mill body which leads to a small foot print and simple foundation. Also, the vertical arrangement does not require any slurry seals or inlet feed pressure. The SMD is a fluidized media mill which means, the impeller speed is high enough to distribute the media throughout the slurry regardless of media density, forcing particle and media contact.

Largest SMD in the world...

The largest SMD in the world, a 1.1 MW device, has recently been commissioned in South Africa in a platinum regrind application.  The advent of larger SMDs allows efficient processing of finely disseminated ore bodies and other challenging applications.

Our engineers will review your specifications and recommend the proper SMD for your application.

Brochure Vertimill and Stirred media detritors - English Download
Brochure Vertimill and Stirred media detritors - Chinese Download
Brochure Vertimill and Stirred media detritors - Russian Download
Brochure Energy efficient comminution circuits - English Download
Brochure Energy efficient comminution circuits - Chinese Download

Related products and services

Previously viewed products