A liquid solvent (extractant) that is not completely miscible with it is added to the liquid mixture to form a liquid-liquid phase, and the purpose of separation is achieved by using the difference in the solubility of each component in the liquid mixture in the two liquid phases. Also known as solvent extraction, abbreviated as extraction.
Single-stage extraction
Single-stage extraction is at most one equilibrium, so the degree of separation is not high, and it is only suitable for occasions where the solubility of solutes in the extractant is very large or the solute extraction rate is not high.
Multi-stage cross-flow extraction
The raw material liquid passes through the various stages in turn, and the fresh solvent is added to the mixing tank at each stage, and the extraction phase and the extraction phase of the last stage enter the solvent equipment respectively, and the extraction phase after the solvent is called the extraction solution, and the extraction phase after the solvent is called the extraction solution.
Features: The extraction rate is relatively high, but the amount of extractant is large, the solvent treatment capacity is large, and the energy consumption is large.
Multi-stage countercurrent extraction
The raw material liquid and the extractant pass through the stages in the opposite direction in turn, and the final extraction phase is discharged from one end of the feeding and introduced into the solvent ** equipment, and the final extraction residual phase is discharged from the end of the extractant and introduced into the solvent ** equipment.
Features: Relatively high extraction rate can be obtained with less extractant, which is widely used in industry.
The extraction process itself does not completely complete the separation task, but only transforms a mixture that is difficult to separate into an easily separated mixture, which must be supplemented by operations such as distillation (or evaporation) to obtain a pure product and a solvent.
Extraction operations are generally used for:
1) The boiling point of each component in the mixture is very close to or forms a constant boiling mixture, which is not economical or cannot be separated by general distillation methods
2) The mixture contains heat-sensitive substances, which are easy to decompose, polymerize or undergo other chemical changes when heated
3) The concentration of the components to be separated in the mixture is very low, and a large amount of diluent must be vaporized by the distillation method, which consumes too much energy.
The extraction operation is a mass transfer process between two phases, and it is necessary to study the equilibrium relationship between the two liquid phases and the mass transfer rate between the phases.
The extraction and separation training series can understand the structure of the extraction column, master the measurement method of the extraction column performance, and understand the enhancement method of the mass transfer efficiency of the extraction column.
Device function 1, understand the structure and application of vibrating sieve plate extraction experimental device. 2. Determine the extraction efficiency. 3. Master the relationship between vibration frequency and extraction efficiency. 4. Full touch integrated control, high-stability data transmission, hardware encryption. 5. The device can realize the mobile terminal to scan the code and obtain the introduction of the device process. Turn the page in 2023