Choosing the Right Extraction Equipment: Kühni™ Columns, Packed Columns, or Mixer-Settlers?
- jesusrangel3
- Jun 20
- 3 min read
Updated: Aug 7
Introduction
Liquid-liquid extraction is a cornerstone of modern process industries, enabling the separation and purification of complex mixtures that are difficult—or even impossible—to handle with conventional distillation. However, the success of any extraction process depends heavily on choosing the right equipment. With Sulzer’s OptimEXT platform, you have access to a full suite of advanced extraction technologies, including Kühni™ agitated columns, packed columns, and mixer-settlers. But how do you know which is best for your application? This article will guide you through the selection process, ensuring optimal performance and reliability for your operation.
Overview of Extraction Equipment
Kühni Agitated Columns (ECR)
The Kühni column is a multipurpose, highly flexible extractor designed for a wide range of process parameters and physical properties. Its unique design—with multiple agitated compartments and turbine mixers—ensures outstanding hydrodynamic performance and reliable scale-up. With the ability to provide more than 30 theoretical stages in a single column, the Kühni column is ideal for processes requiring high selectivity and flexibility.
Key Advantages:
Universal use for most extraction applications
Reliable scale-up and robust construction
High flexibility for varying process conditions
Maintenance-friendly and available in various materials
Packed Columns (ECP)
Packed columns are the solution of choice for high throughput and challenging physical properties. Using Sulzer’s specialized extraction packing, these columns achieve nearly plug flow conditions and a narrow droplet size distribution, resulting in high efficiency and throughput. Pulsators can be added for even better separation performance.
Key Advantages:
High specific throughput and small column diameters
Suitable for low density differences and low interfacial tension
No moving parts for minimal maintenance
Reliable scale-up and revamp options for existing columns
Mixer-Settlers (EMS/ECMS)
When stage-wise contact, long residence times, or batch extraction is required, mixer-settlers provide the perfect solution. These units offer precise control over each extraction stage and are especially useful for processes involving reactive extraction, pH adjustment, or emulsifying systems.
Key Advantages:
Ideal for long residence times and reactive systems
Stage-wise pH adjustment and batch extraction possible
Small footprint with mixer-settler columns (ECMS)
Suitable for extreme phase ratios and challenging separations
How to Choose the Right Solution
Selecting the optimal extractor type is a critical step in every extraction project. The choice should be based on both process and economic criteria, including:
Need for stage-wise contact: Mixer-settlers are preferred.
High throughput with minimal stages: Packed columns are ideal.
Flexibility and wide operating range: Kühni columns excel.
Physical properties: Consider density difference, interfacial tension, and tendency to form emulsions.
Space and maintenance constraints: Packed columns and mixer-settler columns offer compact solutions.
Sulzer’s experienced team can help you navigate these criteria, using feasibility studies, pilot trials, and advanced modeling to ensure the right fit for your process.
Case Study Examples
Example 1: Chemical Industry
A specialty chemicals producer needed to separate components with similar boiling points and a tendency to form emulsions. Sulzer recommended a Kühni agitated column, which provided the necessary flexibility and selectivity for reliable, high-purity separation.
Example 2: Hydrometallurgy
A mining operation required long residence times for metal extraction from electrolytic solutions. Mixer-settlers were chosen for their ability to handle stage-wise pH adjustments and deliver consistent, high-yield results.
Example 3: High-Throughput Application
A petrochemical plant needed to revamp an existing extraction process to increase capacity. By switching to a packed column with Sulzer’s extraction packing, the plant achieved higher throughput and efficiency without major equipment changes.
The Value of Partnering with Sulzer
Choosing the right equipment is only the first step. Sulzer’s OptimEXT platform is backed by decades of engineering excellence, state-of-the-art pilot facilities, and a global network of experts. From feasibility studies and pilot testing to reliable scale-up and performance guarantees, Sulzer ensures your extraction process is optimized for success.
Conclusion
Selecting the right extraction equipment is essential for stable operation, optimal performance, and long-term reliability. With Sulzer’s OptimEXT platform, you can be confident in your choice whether it’s a Kühni agitated column, packed column, or mixer-settler. Let Sulzer help you achieve efficient, cost-effective, and scalable liquid-liquid extraction tailored to your unique process needs.
Contact Us
Ready to optimize your extraction process?
