Most of tungsten is lean ore with dilution rate of over 80%. And this makes it important to remove most of the waste stone before gravity separation. And the main pre-separation method in China is hand-selection. Heavy-midum method and photoelectricity separation has been used sometimes while the equipment involved is heavy-medium separator and photoelectricity separator.
b. gravity separation
The beneficiation method for wolframite tungsten is gravity separation because of tungsten's big density. Gravity separaton can separate it from material with density lower than 3.5-4. Quartz wolframite tungsten is of large grain size and gravity separation can do a great job in this situation.
In gravity separation, jigger and shaking table is the common machines involved. For coarse or block tungsten, jigger is used commonly. Usually, the ore needs screening before jigging. Jigging is added in the milling phases to recover the block tungsten and to reduce pelitization of tungsten. The concentrate from jigger accupies over 50% in the tungsten beneficiation factories.
Shaking table is used for the fine ore separation with its great beneficiation efficiency. And strict classification is necessary before the shaking table, and usualy water spiral classifier is used here.
c. mud tungsten separation
Floatation separation is adopted for the mud tungsten separation. After trial and error, flow sheet of branch crossflow floatation and different-speed selection and agitation is used to gain the great beneficiation efficiency with chemicals-saving.
As to magnetic separation, wet intensity magnetic separator is adopted to separate tungsten with great efficiency.