Batch vs. continuous powder mixing

Determining the right powder mixing equipment for your production process

Industrial powder mixing techniques vary tremendously depending on the application. While mixer types and processing methods abound, all industrial powder mixing processes can be defined as either a continuous or batch mixing system:

    • Batch mixers – Ingredients are loaded into the mixer, processed until the powder is homogenous, then discharged as a single batch. Mixing a new batch requires repeating these steps, perhaps with additional intermediate steps for cleaning the mixer between batches. Because batch mixing is a sequential process, the output is measured in kilograms per batch.

    • Continuous mixers – An uninterrupted stream of ingredients flows into the mixer from above. The ingredients are processed as they travel through the mixer, and a continuous stream of homogenized powder flows out of discharge nozzle. Every stage of a continuous flow process takes place continuously and simultaneously within a specified timeframe, and so their output is measured in kilograms per hour.

When choosing powder processing equipment, many factors can influence whether a batch or continuous process is the better choice. While continuous and batch mixing both have their perks and downsides, and both methods are perfectly legitimate ways to mix powders, one or the other may be better suited to your product or processing environment.

Here are the key differences between batch and continuous mixing in powder processing, their respective advantages and disadvantages, and a selection of amixon® mixers suited for these processing methods.



Powder processing in batch mixers

Batch mixing finds application across diverse manufacturing and processing industries to create products in specified amounts or groupings. Common examples of powdery products that are processed in batch mixers include pharmaceuticals, cosmetics, nutritional supplements, and baby formula.

Advantages of batch powder mixing

In powder processing, batch mixing systems have the following key advantages over continuous mixers:

    • Fine-tune the mixing process – Because every batch can be precisely adjusted, batch mixing is often preferred for products that must undergo strict quality testing, such as pharmaceutical powders. This flexibility also makes batch mixing ideal for powdery ingredients that are chemically sensitive and prone to changing over time.
    • Mix multiple formulations with the same equipment – From batch-to-batch, the same mixer can be used to blend any number of different ingredients and formulas. This can be particularly advantageous for mixing different flavors of the same product, such as muesli or cereal variations.
    • Option of premixing – Batch mixers make it possible to first blend a portion of the ingredients before loading additional ingredients. In this way, batch mixers can perform multiple mixing processes, such as intensively deagglomerating additive ingredients before gently homogenizing them with the bulk material.
    • Trace products back to a particular batch – After discharging, the mixed end-product can be labeled with a batch number. Batch mixing makes it easy to identify which products were mixed when, should follow-up later be necessary. Traceability makes batch mixing well suited for mixing pharmaceuticals or other highly regulated products where the documentation of batch integrity is crucial.
    • Ideal for plants with smaller capacities – Batch mixers generally have lower operational and installation costs than continuous mixers. This is especially true for facilities that don’t need to mix tremendous volumes of powder at rapid speeds.

Disadvantages of batch powder mixing

Compared with continuous mixers, batch mixers have the following limitations and disadvantages:

    • Down-time between batches – Pauses are inherent to batch mixing because only one stage of the production process can take place at a time. While one stage is in progress, all others must stand still.
    • Labor intensive – Batch mixing involves several steps and changeovers, which can make the powder mixing process more hands-on than a continuous flow process would be.
    • Increasing output means increasing mixer size – Generally speaking, to get a higher batch yield, you need a larger batch mixer. Smaller facilities may not have enough space for a batch mixer that is large enough to produce the desired kg/batch output.
    • Not ideal for large scale, accelerated production environments – Because batch mixing processes are generally slower and more labor intensive than continuous flow processes, they may not be efficient enough for applications that require rapid manufacturing.

While batch mixing may be limited in these ways, innovations in powder processing and large batch technology have made tremendous strides to improve cycle times and efficiency.

ComDisc®, a proprietary technology from amixon®, enables batch mixers to be rapidly discharged with a product yield of up to 99.997%. Furthermore, amixon® batch mixers are designed with large inspection doors that give ergonomic access to the mixing chamber, cutting down on cleaning and drying time between batches.



Powder processing in continuous mixers

Continuous mixing is preferred in large-scale powder processing applications requiring that a single blend is produced at a rapid rate. Many dry and powdery food products are mixed in continuous flow processes, from instant beverage granules to assorted snack foods. Granulators and powder agglomerators are common examples of mixing equipment that typically operate continuously.


Advantages of continuous powder mixing

In powder processing, continuous mixing systems have the following key advantages over batch mixers:

    • Greater efficiency – In continuous processes, every mixing stage from loading, to mixing, to discharging takes place simultaneously and without pause. Continuous powder mixing eliminates both downtime between batches and the manual labor required to handle changeovers.
    • High output at compact sizes – Compared to a batch mixer of a similar volume, continuous powder mixers can produce much higher quantities of mixed products in a given timeframe. Even processing facilities with severe space limitations can mix large volumes of powder by using a continuous mixer.
    • Operationally less resource intensive –In addition to their smaller sizes, continuous powder mixers generally require less power and manual labor than a batch mixer would need to process the same volume of mixed goods.
    • Automation-friendly – Continuous mixers are ideal for automated production environments, as their operation can be programmed and monitored with IoT technology.
    • Minimized segregation and product loss – Because mixed goods are discharged from a continuous mixer in an uninterrupted flow, less product is lost to residue and segregation overall.



Disadvantages of continuous powder mixing

Compared with batch mixers, continuous mixers have the following limitations and disadvantages:

    • Limited precision – Especially if many ingredients are to be blended, continuous powder mixing processes may not be capable of mixing exact formulations requiring strict blend uniformity. This makes continuous mixers unsuitable for many critical applications, such as mixing pharmaceutical powders or fine ceramics.
    • Reduced flexibility –Continuous powder mixers are usually programmed for one specific formulation and their settings cannot be quickly changed to process different formulas or volatile materials. This lack of flexibility makes continuous mixing less than ideal for processing chemically sensitive powders or variable products.
    • Extensive ongoing maintenance –Continuous mixers are part of an ecosystem of processing equipment, and so any malfunction can bring the entire production line to a halt. Meticulous calibration and ongoing maintenance are crucial to preventing stoppage.
    • Require a robust sampling and testing procedure – Keeping track of the quality of powders mixed in continuous flow processes can be a complicated endeavor, because contaminants or variations in blend uniformity cannot be traced back to a single batch. In industries where consumer safety is a concern, a robust quality assurance program would be needed.

Batch and continuous powder mixer models

amixon® mixing technologists have engineered a conical powder mixer with a spiral mixing blade capable of operating either as a batch mixer or a continuous mixer. The AM batch mixer and AMK continuous mixer both initiate a three-dimensional flow within the mixing goods and can be programmed for a range of mixing intensities from gentle homogenization to intensive deagglomeration.

Whether your process requires a continuous mixer or a batch mixer, the amixon® team of engineers collaborates with you to determine and calibrate the precise filling levels, mixing retention, and cycle times for your powder mixing equipment.

The result is a powder mixer that is expertly customized to both your product and your workflow.



Learn More: Powder Mixing

Three dimensional mixing action
Three-dimensional mixing action

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amixon® U.S. Sales Representative

AZO Incorporated
Kevin Pecha
4445 Malone Road
Memphis, TN 38118
USA

Telephone +1 901 794 9480
Telefax +1 901 794 9934
E-Mail: kevin.pecha@azo.com

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