Rotary Batch Mixers Also see: Rotary Glass Batchers, Rotary Batch Dryers/Coolers, Mini Rotary Batch Mixers

COMPARE WITH RIBBON BLENDERS, PADDLE BLENDERS
AND PLOW BLENDERS

Munson is the only manufacturer of all of the above types of mixers/blenders, and is uniquely qualified (and motivated) to provide the advantages and disadvantages of each relative to your application, accurately and objectively.

The following table outlines the inherent differences between Rotary Mixers and stationary-horizontal blenders popularly known as Ribbon Blenders, Paddle Blenders and Plow Blenders.

The following ratings are generalizations that do not apply to all applications. Please consult factory for specific equipment recommendations.

A = Excellent

B = Good

C = Fair

D = Poor

MIXER ATTRIBUTES/ CHARACTERISTICS	BATCH MIXERS
	Rotary Batch Mixer	Rotary Batch" Mini" Mixer	Ribbon, Paddle & Plow Blenders
Abrasives	A	A	C
Abrasive materials	A	A	C
Brittle materials	A	A	D
Chips	A	A	C
Coatings	A	A	C
Complete discharge	A	A	C
Critical mixes	A	A	C
Crystals	A	A	C
Emulsions	C	C	B
Fibrous materials	B	B	B
Fragile materials	A	A	D
Gentle blending	A	A	C
Glass cullet	A	A	C
Granulars	A	A	B/C
Interlocking materials	B	B	B
Irregular chips	A	A	C
Large Variance in Particle Sizes	A	A	D
Low maintenance	A	A	B
Lowest energy/amt Of material blended	A	A	C
Lowest initial cost	B	B	A
Minor liquid adds	A	A	B
Pastes	D	D	B/C
Pellets	A	A	C
Powders	A	A	B
Rapid blending	A	A	C
Rapid sanitizing	A	A	C
Slurries	D	D	B
Sticky/tacky materials	D	D	B/C
Uniform blending	A	A	C
Uniform liquid additions	A	A	C

General disadvantages of Rotary Batch Mixers

Generally speaking, Ribbon, Paddle and Plow Blenders offer lower initial cost and a smaller footprint than Rotary Batch Mixers, and can be charged at any point above their large, flat lids. They are also better suited to non-free-flowing materials and reducing agglomerates due to the aggressive action of their agitators being forced through the material contained in a stationary, horizontal mixing vessel.

General advantages of Rotary Batch Mixers

Rotary Batch Mixers can blend a batch with 100 percent uniformity in 2 to 3 minutes, versus about 8 to 15 minutes for stationary horizontal blenders (Ribbon, Paddle and Plow Blenders). And unlike stationary horizontal blenders whose agitators are forced through the material throughout relatively long cycle times, degrading all but the most cohesive of particles, Rotary Batch Mixers create a gentle tumbling action over short cycle times, virtually eliminating product degradation, and they evacuate 100 percent of the batch, allowing fast, thorough sanitizing and product changeovers.

Specific advantages of Rotary Batch Mixers

Blend Quality:

• Rotary batch blenders will provide a significantly higher blend quality vs. a ribbon blender
• Complete and homogenous distribution of all materials regardless of particle size, shape & density.
• Micro additions are perfectly dispersed throughout the batch with additions as low as 1/10 of a %.
• Munson's unique internal mixing flight design ensures all material is in motion at all times. There are no 'dead zones' where material sits and segregates or does not mix.
• Internal lifter and baffles (mixing flights) provide a dynamic and river like flowing action of materials. This creates the Rotary Batch Blenders exclusive constant four way mixing action of tumbling, turning, cutting and folding.
• The blending action of the Rotary is the most gentle available and will not degrade materials regardless how fragile they are. By contrast, a Ribbon blender has an agitator that is forced through materials in a stationary trough and tends to compress and grind material, creating unwanted fine particles.
• The agitator in Ribbon Blenders rely on an agitator passing through materials in a stationary trough and can have noticeable zones of stagnant material, especially if the equipment is over filled.
• Rotary Blenders can blend batches as small as 10-15% of the machines rated batch capacity without jeopardizing blend quality whereas a ribbon blender cannot be operated much below the rated fill capacity and certainly not less than 50% full.

Cycle Times:

• Typical batch times in a Rotary Blender are 2-3 minutes this includes filling, blending & discharging, 5 minutes on the outside.
• If liquid additions are added, the length of time to spray liquid must be added to the cycle time.
• Typical cycle times in Ribbon Blenders are no less than 5-7 minutes for an adequate blend (non-critical). Tests have been performed on medicated calves milk powder where the same percentage micro addition was added to both a Ribbon Blender as well as Rotary Batch, the results did not show up in an analysis of a 20 minute blend in the Ribbon Blender but where homogenous after 3 minutes in the Rotary Batch (test performed with Land O'Lakes)

Cleaning:

• Because the Rotary Batch discharges virtually 100% of batch material the clean-out time is significantly less than that of a Ribbon Blender.
• Tank cleaning nozzles can be incorporated in the Rotary Batch to completely clean the internal surfaces. Also the machine can be supplied with multiple clean-out doors for easy access to internal surfaces.
• Ribbon blenders have a stationary trough and there is a 'heal' of material left behind due to the clearances between the ribbon & trough, therefore the cleanout is more difficult.
• Also when adding liquids, the ribbons tend to get a build-up of material on them that requires scraping off to clean (also means the liquid did not get on the product but on the steel!).
• Cleaning a Ribbon Blender is much more evasive because the ribbon element is not removed for cleaning and therefore all surfaces have to be accessed and wiped down. This is very time consuming.

Liquid Additions:

• The Rotary Blender is designed specifically for liquid additions. Material gently tumbles & cascades directly in front of the fanned spray nozzle creating and even distribution of liquids. As soon as a particle is introduced with liquid it is moved away and new material is presented. This action guarantees all material is coated evenly without the creation of 'hot spots'
• Ribbon Blenders spray liquid on the top surface of the batch material in the machine. This system oversprays / over saturates material and relies on the blenders ability to pass the 'wet' material into contact with dry material. It is an extremely inefficient means of adding a liquid to a batch of material. Lumps are often created and hot spots are almost always an issue. To alleviate this, the spray can be added in an extremely fine droplet size but this adds valuable time to the batch process.

Energy Efficiency:

• Rotary Blenders typically utilize no more than 1 ½ - 2 HP per 1,000 lbs of material.
• Ribbon Blenders typically use between 5-6 HP per 1,000 lbs of batch material
• This equates to significant saving annually. A comparison was performed on a Rotary Batch with 10 HP vs. a comparable sized Ribbon with 50 HP (very heavy batch of glass materials) and the annual savings was in the vicinity of $25,000- $30,000.

Cost:

• On a batch size-to-size comparison, Ribbon Blenders will typically be 10-15 % less than a Rotary Batch mixer. The same hourly production requirements can be handled in a smaller Rotary Blender than Ribbon Blender significantly reducing the overall capital expenditure and equipment footprint of a process line. Based on hourly throughput capabilities the Rotary Blender is priced comparably if not lower than a Ribbon Blender.

Equipment Wear:

• Because there are no internal moving parts in a Rotary Batch, the wear is not as much a concern as in a Ribbon Blender. The life expectancy when blending an abrasive product in a Rotary Blender is at least 5 times greater than that of a Ribbon Blender.