Mixing

What is Mixing?

Mixing is a basic operation process in the chemical engineering technology. The mixing process, the opposite operation of the breakup process, is the systematic aggregation of at least two materials of different kind being converted into a preferably homogeneous mix. The aggregate state of the raw materials may vary between gaseous, liquid, solid. The mixing operation is a process carried out gradually. The quality of a mix is defined by taking samples and by an analytical evaluation. Please consider that indeed an optimum mixing condition may be obtained which may be changed for the worse during the proceeding mixing time.

Examples of Mixing Conditions

Examples of Mixing Conditions

A: Complete separation of the single components
B: Ideal mix (not achievable in reality)
C – E : Real mixing conditions
F: Real, homogeneous mix

Concerning the mixing aggregates we distinguish between static and dynamic mixers. Static mixers are stationary systems through which the material is flowing. The mixing effect is exclusively achieved by vortexing the flow with the aid of integral elements. Precondition for the application of static mixers is the pumpability of the original materials.
Contrary to static mixers, dynamic mixers make for a mechanical mutual relative movement of the individual components.

Dynamic mixers are divided in rotary-drum mixers and compulsory mixers. Free fall mixers exclusively utilize the gravity for moving the material. A typical example for a rotary-drum mixer is the conventional cement mixer with its rotating drum.

Compulsory mixers, however, are working with moving, mostly rotating mixing elements which are installed in the mixing room. The mixing elements make for a systematic acceleration and a relative mutual movement of the raw materials. The movement conditions may vary depending on the design of the mixing elements. Compulsory mixers are suitable for universal application. Possible applications are mixes of solids-solids, solids-liquids, liquids-liquids, solids-gas and liquids-gas.

Another difference is made between Shear Mixers and Impeller Mixers, depending on the movement conditions prevailing in the compulsory mixer. Shear mixers exclusively generate relative movements without expelling single particles out of the material, whereas, subject to the speed, impeller mixers generate a mechanical fluid bed of varying degrees whereby individual particles are completely expelled out of the material matrix falling back to another place. Hereby the continuously working Annular Layer Mixer takes up an exceptional position.

The movement condition of the horizontal compulsory mixers may be characterized by the nondimensional Froude number.

different mixer

Applicable:

With :
v = peripheral speed of mixing elements
r = radius of mixing drum
g = acceleration of gravity

Compulsory mixers are suitable both for batch processes as well as for continuous applications.

Mixing with Lödige

Lödige is offering a large variety of mixing systems for industrial applications. For these applications dynamic compulsory mixers are used exclusively. Both horizontal mixers and vertical systems are available. In the first case the mixing shaft and the tools are horizontally installed, thus achieving, at corresponding movement, a product reaching from a loose product bed up to a mechanically generated fluidised bed. In the second case the mixing shaft is installed in vertical direction, whereby a socalled vortex is built at corresponding movement. The installation of fast-rotating chopper heads enables the mixing of products tending to lump formation. Due to the mixing tools, the material to be mixed is hereby specifically fed to the activity area of the chopper head.

Horizontal Ploughshare Mixer

Besides the conventional ploughshare mixing tools a large variety of modified mixing tools is available, facilitating an optimum adaptation of the mixing tools to the individual material. The Lödige systems enable therefore the gentle mixing of sensitive products and the concerted shear introduction into the material. Special mixing tools are available to be used for the reduction of wear or to avoid wall deposits.
Lödige is offering systems both for batchwise as well as for continuous applications.

Mixing with Lödige means the customer-specific choice of the optimum mixing technology based on the experience gained with more than 20.000 systems supplied for applications of various kinds. An inhouse test centre is available facilitating the mixer parameter design for new applications or for the process optimization. In this test centre the optimum mixer design will be determined in cooperation with processtechnical specialists.

Machines for mixing

Lödige is offering various machine types for the process-technical mixing applications. The horizontal Lödige Ploughshare® Mixer can be used both for batchwise processes (type FKM) as well as for continuous applications (type KM). In vertical mixing and granulating systems the mixing process is effected only batchwise: For this purpose the machine type MGT (mainly pharmaceutic and cosmetic applications) is used. The Annular Layer Mixer type CM is applied for continuous processes.

In the following please note a survey on the different machine systems:

Ploughshare® - Mixer

Mixers / Mixing Granulators

 

Special Machines

We should be pleased to assist you in choosing the optimum systems for your application.

Always the right mix

Always the right mix

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