For concentration (separation of gangue minerals) several methods can be applied, depending mainly on the composition of the ore. They include ore sorting, gravity methods, flotation, magnetic, and electrostatic separation.
Beneficiation of tungsten ores by gravity was the classical method, followed by a “cleaning” step. The recovery depends on the ore characteristics (mainly liberation size) and ranges typically between 60 and 85%. The main loss is in the slimes, because the tungsten minerals are the most friable ones present in ores.
As regards“cleaning,” for example, a roast process can be applied to convert pyrite to magnetic separation together with garnet and pyroxene. Another cleaning step in the presence of sulfide minerals would be a sulfide flotation.
Gravity methods can also be applied for both scheelite and wolframite. The usual equipment consists of spirals, cones, tables, and a sink-float.
In order to optimize the yield, modern technology includes the following additional steps or combinations:
Preconcentration. This could be accomplished by sorting, use of jigs, or heavy media separation.
Whole Flotation. If tungsten ore mineralization is too fine, the total amount of mined ore can be subject to flotation.
Scavenging Circuits. These are combinations of gravity separation and flotation to recover the loss via slimes occurring in the classical procedure.
没有评论:
发表评论