The Powder of Separation - Dense Medium Ferrosilicon
Dense medium ferrosilicon is a fine metal powder, with size distributions below 255 micron. It is used in Dense Medium Separation processes, where the powder is mixed with water to the desired medium density, and added to a DMS plant. The separation takes place in either a static  (Drum) or a dynamic (cyclone) separating unit.

Dense Medium Separation is also known as Heavy Medium Separation or the Sink-Float Process. In order to achieve separation, it is necessary to have physical characteristics causing differentiating behavior such as hardness, color, shape, electric, magnetic, surface, radioactivity or DENSITY. Dense medium separation is a process well known throughout the mining and metal recycling industries where metals are recovered by utilizing the difference in density of the products to be separated.


Dense medium separation is the process used to separate particles of different densities in a medium made up of water and heavy solids (suspension). In this suspension the heavy particles will sink and light particles will  float.

The ferrosilicon suspension is made up  of water and a ferrosilicon powder, where the ferrosilicon powder has a relative density of 6.7 – 7.1 g/l and contains 14-16% silicon.

Both  the  physical and chemical properties of the ferrosilicon  contribute to separation efficiency and medium recovery. It is therefore important that the quality of the ferrosilicon is maintained and the correct grade for the application is selected.

Important characteristics of the ferrosilicon suspension are medium density, viscosity and stability.
The Dense Media Separation process consist of both the separation and medium recovery circuits. The ferrosilicon properties are designed to maximize separation efficiency while optimizing medium recovery.

Dense medium beneficiation is a well established process in the mining and metal recycling industries.
Medium Density:  The concentration of ferrosilicon solids in the medium. 
Medium density is increased by adding more ferrosilicon solids, and reduced by adding water. Medium density will determine at which density the separation will take place.

Medium Viscosity: A measure of the medium's resistance to flow. 
Viscosity is determined by the concentration, shape and size distribution of the solids making up the medium. For dense medium separation processes, a low medium viscosity is desired. High viscosity result in increased chance of particle misplacement and hence reduced separation efficiency.

Medium Stability: The propensity of the medium solids to settle out. 
As the relative density of the solids is higher than water, the medium is inherently unstable.  The inverse of the rate at  which the medium solids settle out under gravity is a measure of the medium's stability. Generally a stable medium is desired. Unstable media will settle in pipes and pumps, while density gradients can occur in the separators, impairing separation efficiency. 
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