Dispersants are versatile modifiers that reduce gangue particles that cling to sulfide minerals.

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  • Disposes of slimes on particle surfaces.
  • Allows for a purer concentrate.
  • Have multiple functions – can work as a depressant or activator.
  • Are inorganic compounds and organic polymers.

Dispersants are reagents that dispose the slimes that often agglomerate and cover the surfaces of larger particles, therefore preventing them from being recovered. 

With the use of a dispersing agent a purer concentrate is obtained because they decrease the extent to which gangue particles cling to the sulfide minerals. Most dispersing modifiers are also either depressants or activators. In short, they have multiple functions.

Dispersing reagents are inorganic compounds and organic polymers. 

Dispersant applications

These dispersants are shown with their typical applications:

Sodium silicate – A depressant for gangue slimes and siliceous gangue minerals in sulfide and non-sulfide flotation.

Sodium metasilicate – Disperses gangue slimes without raising pH abnormally.

Quebracho – An excellent depressor for calcite in fluorspar flotation. Also a depressant for wolframite. 

Starch – Depressant slime gangue when floating sulfides. 

Gum Arabic – A good dispersant and depressant for gangue slimes. 

Sodium silico-fluoride – Depressant for quartz and feldspar in flotation of spodumene.

Lactic acid – Depressant for mica.

Polyphosphates – Used as gangue depressants during pyrochlore flotation and also during flotation of phenacite and bertrandite and depressing of iron sulfides and alkaline earth minerals during flotation of copper–molybdenum ores.

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