In modern chemical, pharmaceutical, environmental protection, and hydrometallurgical industries, how to efficiently and precisely separate and purify target components from complex liquid mixtures has always been a core challenge in production processes. As a classical yet powerful separation method, liquid–liquid extraction plays an irreplaceable role. The mixer settler, as the key equipment for implementing this technology, has become the preferred choice for many enterprises to enhance quality and efficiency thanks to its outstanding performance and stability.
Technical Principle
The working principle of the solvent extraction mixer settler is based on the difference in solubility of substances in different solvents. The process can be summarized in three core steps:
- Mixing and Mass Transfer: The feed solution containing the target solute (such as metal ions or organic compounds) is introduced into the mixing chamber of the mixer settler together with an “extractant” that is immiscible or partially miscible with it. Under vigorous agitation (typically by a mechanical impeller), the two liquid phases are fully dispersed and mixed, creating a large interfacial contact area. The target solute transfers from the feed phase (aqueous phase) into the extractant phase (organic phase).
- Phase Separation: After mass transfer, the mixed liquid flows into the settling chamber. Here, agitation ceases, and due to the inherent density difference between the two liquid phases, the mixture naturally separates under gravity. The denser phase (usually the aqueous phase) settles at the bottom, while the lighter phase (usually the organic phase) rises to the top, forming two distinct and separate layers.
- Separate Collection: At the end of the settling chamber, adjustable weirs or overflow pipes are installed to precisely direct the separated light and heavy phases out of the unit, thereby completing one extraction cycle. Depending on process requirements, multiple mixer settler units can be connected in counter-current stages, greatly enhancing extraction efficiency and product purity.
This “mixing–settling–discharge” physical process perfectly integrates chemical transfer (mass transfer) with physical separation (settling), achieving continuous, stable, and efficient industrial production.
Wide Applications
The solvent extraction mixer settler has found applications across almost every industrial field requiring precise separation:
Hydrometallurgy: The most classical application area of mixer settler. They are widely used for the extraction, concentration, and purification of metals such as copper, cobalt, nickel, zinc, uranium, and rare earth elements. For example, efficiently extracting and concentrating copper from low-grade ore leach solutions to produce high-purity cathode copper.
Chemical Industry: Applied in the separation and purification of various organic acids, phenols, aromatic hydrocarbons, aliphatic amines, and other organic compounds. For instance, recovering valuable products such as phenol and acetic acid from coal chemical or petrochemical wastewater.
Pharmaceutical Industry: Plays a key role in the extraction and refinement of antibiotics, alkaloids, hormones, and other pharmaceuticals, meeting the stringent requirements for high purity and safety in drug production.
Environmental Protection: Used in industrial wastewater treatment to efficiently remove or recover toxic and hazardous substances such as heavy metals (e.g., chromium, cadmium, mercury), phenols, and organic solvents, enabling compliant discharge and resource recycling.
Food Industry: Applied in the extraction of natural products, such as edible oils, flavors, and pigments from plants. The gentle process preserves the natural characteristics of the products.
Nuclear Fuel Reprocessing: Used in the recovery and treatment of spent nuclear fuel, for the separation of nuclides such as uranium and plutonium.
The solvent extraction mixer settler is a time-tested, mature, and reliable cornerstone of industrial processes. With its intuitive principle, robust operation, and outstanding performance, it continues to create immense economic and environmental value for customers across industries worldwide.
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