elutrition Flashcards
definition
-is the process in which the particles of the fluid move in a direction opposite to that of the sedimentation (downward movement)
-process of separation of a substance into powder of different degree of fineness by stirring the substance with larg volume of liquid in which it is insoluble and withdrawig the liquids at different heightse
explanation
-In gravitational sedimentation the particles will move vertically downward while the fluid travels vertically upward.
-If the velocity of the fluid is less than the setting velocity of the particles, then the particles will move downward against the stream of fluid. If the setting velocity of particles is less than the velocity fluid, the particles will move upward.
-In other words, small size particles will move upward while the large size particles will move downward.
-So, Elutriation is the process of separation of fine particles from course particles. The particles size can also be measured by this process. The air Elutriation usually give sharper fractions of small and large particles then water Elutriation.
apparatus used
appartus used is called elutriator. there are two types:
-gravitational elutriation
-centrifugal elutriation
gravitaional
in gravitational elutriation the fluid particles move downward due to sedimentation (force of gravity) while the lighter partiles remain upward.
centrifugal
-centrifugal causes the fluid stream to rotate under high centrifugal force to suspend the particles
-these particles which are too large to rotate with direction of flow of fluid, separte out on the wall of the elutriator. however, the fine particles move easily with the stream of fluid
uses
-heavy and light kaolin can be separated by this process, because the particles of heavy kaolin move downward and those of the light kaolin moce upward
-it is upward used following a size reduction process with the objective of separating oversize particles which may be returned for further grinding
