Continuous or Batch Mixing - Which Is Right For You?

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BULK MATERIAL HANDLING EQUIPMENT

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July/Aug 2023

MIXING TECHNOLOGY

Continuous and Batch Mixing

When designing the optimal process for bulk material mixing, customers always ask whether a batch or continuous mixer would serve them best. The answer depends on the application and requirements.

What quantity of material are you mixing?
Your product specifications?
What homogeneity is required?
Your current pre-mixing and post-mixing operations?
Your material handling equipment?
Your specific product formulation requirements?

Batch Mixing

With batch mixing, a set quantity of ingredients are loaded into the mixer and mixed until it reaches the desired homogeneity. It's discharged from the mixer in a single batch measured in kg/batch. This is repeated for each batch, filling and emptying the mixer each time.

Continuous Mixing

Continuous mixing processes ingredients in a continuous stream without any starting and stopping. Material is fed into the mixing chamber per the formulation and continuously discharged, streamlining the production process. The output is measured in kg/hr.

Munson Rotary Batch Mixer in Use Since Early 1980's

Throughput and Cost: Continuous mixers quickly process large quantities of ingredients and require minimal floor space. For higher throughput, large-capacity batch mixers, integrated with efficient ingredient handling systems, are often used.

Processing time: The time it takes for the material to flow into the mixer through to the discharge outlet is known as the rate per moment (RPM). For longer RPMs, batch mixing is more appropriate because applications that rely on an even product blend need to be mixed quickly.

Productivity: Batch mixing is cheaper than continuous mixing for lower and mid-size production rates. It also requires less equipment and can be more easily adapted to changing production needs. Continuous mixing can offer a faster process for high volume throughput in a shorter time.

Energy costs: By eliminating frequent starts and stops, continuous mixers typically utilize less energy per throughput cycle than batch mixers.

Labor costs: Continuous mixers require less human interaction. Labor costs are generally lower than with batch mixers.

Founded in 1823, Munson Machinery is a leading supplier of mixing and blending equipment. They offer mixing solutions for a wide range of industries and applications.

MUNSON® Fluidized Bed Mixers

For Low to Medium Density Bulk Materials

With cycle times of 10 seconds to two minutes, the MUNSON Fluidized Bed Mixer is among the fastest of all mixers. It is recommended when mixing low- to medium-density materials (≤50 lbs/ft3 or ≤800 kg/m3) ranging from powders to pellets — particularly friable materials — with or without liquid additions, in applications requiring short cycle times, relatively gentle product handling and infrequent wash downs.

Flat, angular paddles with overlapping paths sweep material from two parallel U-shaped troughs toward the center and upward, causing it to become airborne in a "fluidized zone". This is where particles of batch ingredients intersperse, regardless of disparities in particle size, shape or bulk density.

The "fluidized zone" is an ideal location to spray high- or low-viscosity liquids, where they can disperse more easily, and be added in relatively high volumes while maintaining free-flowing characteristics of the batch.

This fluidized mixing action creates less shear than other agitated blenders. Together with the short mixing times, the result is less product degradation.

Another advantage of the fluidized bed mixer is the rapid discharge through its full-length, drop-bottom gates, allowing material to empty from the machine rapidly. Ribbon, paddle and plow blenders leave a pronounced "heel" of material in the trough following discharge. The fluidized bed mixer evacuates a much greater percentage of material, reducing the need to manually remove — and waste — material between product changeovers.

MUNSON® Rotary Continuous Mixer

Mix Large Volumes Uniformly, Gently, Rapidly and Dust-free

If you want to dramatically cut labor and operational costs when mixing dry bulk solids, look no further than Munson's Rotary Continuous Mixer. With or without liquid additions, it delivers uniform blends — typically in one to two minutes residence time — gently and with low energy use.

Low cost mixing of long product runs
Low labor costs compared to batch mixers
Gentle action prevents material degradation
Accurate blend ratios to 99.9%
Rapid mixing: 1 to 2 minutes residence time typical
Lowest energy use per amount of material blended
Stationary inlet and stationary outlet allow for hard piping
Handles abrasive and corrosive products, and materials with high bulk densities
Automatic material evacuation at the end of product runs using an optional reversing discharge weir
Small footprint per amount of material processed
Industrial and sanitary designs, construction and finishes
Long life with minimal maintenance