Centrifugal extractor

A centrifugal extractor used for the continuous extraction of valuable materials (metals, drugs, flavors, vitamins, etc.) from a liquid phase into another liquid phase with the aid of centrifugal force. In this case, two immiscible liquids (carrier / solvent) are intensively mixed in a mixing chamber of different densities between the housing wall and the outer wall of the rotor. The intensive mixing creates small droplets with large surface areas that allow optimum mass transfer from the carrier phase to the solvent phase. A centrifugal extractor then uses the centrifugal force to separate the finely dispersed droplets.

Single-stage centrifugal

The sectional drawing shows a cross section through a single-stage centrifugal extractor. About the two inlets ( Inlet ) are supplied either already pre-mixed or unmixed two liquids (blue / yellow) the mixing region (green ) of the centrifuge. In the intermediate range between the rotor and the housing wall, the phases are strongly mixed. Form small droplets and thus a high surface area in order to optimize mass transfer of the washing and extraction processes. The intensity of the mixing can be selected on the rotor speed. The dwell times in the rotor is 30 seconds up to two minutes per step. In the rotating rotor, the two liquids of different densities are separated by the centrifugal force and discharged through the respective outlet ( heavy or light phase).

Separation DF (direct feed)

"Feed Direct" When done feeding the mixed liquids (green) through the bottom plate directly into the rotor, thus minimizing shear forces on the product. The two phases are continuously into a heavy phase (blue) and a light phase (yellow) separated.

Mix & September

In " mix & sep " two immiscible liquids (blue and yellow ) of different density are contacted outside of the rotor. Through the narrow gap between the rotor rotates and static housing wall resulting shear forces very small droplets are formed with large surfaces for the ideal mass transfer from one phase to the other phase. In the rotor and then the two phases are separated.

Mehrstufiuge centrifugal

The to be extracted phase ( heavy phase on the block diagram), which initially contains and the solvent ( light phase on the diagram ), which may not be miscible with the to be extracted phase and must have a different density, one or more solvates, flowing in counterflow in the Extraktorrotor in which piled up, mechanical parts form a certain number of stages. In each stage of the successive mixing and separation processes permit the solution of the solvate in the solvent.

Each stage consists of the following parts:

  • A mixing chamber in which the two phases are mixed and the transmission to extract the solvate to take place. A fixed sheave allows the mixing of the two phases and the formation of a fine emulsion. It acts as a pump which draws the two phases from the precursors.
  • One decanting chamber, in which the two previously mixed liquids are separated by centrifugal force. 2 weirs stabilize the deposition zone regardless of the quantities of liquid. The position of the phase boundary depends on the diameter of the heavy phase weir. The weir is replaceable and is adjusted to the density ratio of the two phases.

Multistage processes

Multistage processes are needed for applications with several theoretical stages. Each single-stage centrifugal represents a theoretical level dar. cross - and counter-current processes are represented as simple.

Separation DF

Mix & sep

Cross / countercurrent extraction

Battery of 2 for centrifugal countercurrent extraction in 2 steps

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