Transforming Blending Processes with Agitation

A chemical manufacturer was struggling with inconsistent material blends due to the limitations of ribbon blenders typically used for blending dry ingredients. Due to storage and environmental factors, its raw materials are prone to clamping, especially when they absorb moisture and heat. This causes issues with blend uniformity, leading to quality control problems and delays in production.

Inefficient and Contaminating De-Lumping

Before mixing, the manufacturer used a brush lumper. This is a very rough set of brushes, 2-3 in. in length, arranged in the form of a cross that pulverize lumps in the hopper before the material goes into the ribbon blender.

However, this method is far from ideal. The brushes themselves were getting into the blend, contaminating the product, and causing even more problems. They are also expensive to maintain and replace, and they were not doing a good job of preventing clumping in the first place.

Agitator to the Rescue

Milling while you blend has been around since ancient times. Pharmacists used a mortar and pestle to grind and mix ingredients for thousands of years. A grinding process can enhance the solubility, flow, and taste of a product. The milling process will increase the particle surface area and increase the ingredient release. Blending and milling in one step can increase efficiency by 100%. The milling process can be dusty, explosive, and messy. OSHA milling violations are rampant in milling, as are injuries. By combining the two operations, the safety issues are reduced or eliminated.

The chemical manufacturer reached out to Advanced Powder Solutions (APS). APS recognized the limitations of the brush lumper and introduced the manufacturer to GEMCO's machinery and its innovative agitator. It achieves milling functionality, even mixing capability, product uniformity in blend or color, fewer steps and less time spent, reduced environmental cleaning, less fugitive dust, and elimination of hazards for personnel. Unlike the brush lumper, the GEMCO agitator does not contaminate the product, and it provides a much more efficient way to prevent clumping.

Benefits of GEMCO’s Agitator

The benefits of using GEMCO’s agitator go beyond simply solving the clumping problem. Here are some of the key advantages:

Innovative Solution for Powder De-Lumping

The agitator--also known as an impeller, chopper, or intensifier--is used to de-lump, reduce particle size, or improve a sample's standard deviation of a powder blend.

It has several blades attached to a variable-speed rotating bar at speeds up to 3,600 ft/min. The blades are positioned in the “mixing zone” which is in the center of the blender. As the blender tumbles, the powder drops on top of the blades and allows particle size reduction to take place. Unlike a mill that uses a screen to hold material until it has been crushed to a certain size, the agitator uses the time of agitation to determine when it has reached the particle size goal.

De-Lumping Agglomerated Powders

The slow-speed agitator changes the blender into an efficient de-lumper of agglomerated powders. Agglomeration is typically caused by particles or powders adhering to one another because of exposure to environmental conditions such as static, heat, cold, or moisture during shipping or storage. The rotating action of the shaft combined with the custom-designed blades gently de-lumps without reducing the size of the particles. They break up easily and eliminate a screening or milling step to do the same job.

These agglomerates can be from loose to tightly packed and be of any size. To disperse evenly with other powders in a mixer, these lumps must be broken down to their original particle size and free-flowing nature. The particle size of the original powder must be maintained. The consistency of the size reduction is due to the constant and repeated flow of powder over the bar.

The fact that the agitator is not a high RPM hammermill or pulverizer is attractive to chemical processors. It introduces a gentle de-lumping method within the blending step. The dust and noise associated with milling are eliminated since it is done inside the blender vessel. The aggressive force of a hammermill is “overkill” for most chemical powder de-lumping and sizing requirements, but the agitator is slower so there is less heat and less fines generated.

The type, quantity, and shape of the blade help determine the degree of reduction achieved based on the material being processed. A knife-edged blade is for gentle granulation and a flat-edged for more aggressive reduction.

Low Shear for Minute Additive Dispersion

Fragile particles or granules that need to be mixed with a small amount (7% < batch total) of additive, need the energy of the “slow” bar to achieve the blend without reducing the fragile particle size. One example is adding a flow agent to granules for better tableting properties.

High-Speed Agitators

The high-speed bar is used to disperse a small amount of additive (7% < batch total) throughout a batch. These additives need the extra energy of the high-speed agitator to thoroughly disperse them across the blend while macro tumble blending will not. An example is adding colors to plastics or cosmetics. By using the agitator, the color will repeat itself batch after batch. The energy imparted by the agitator accelerates the particles to increase blending momentarily. Since the bar is in the direct blending path, it can increase the blend efficiency.

Conclusion

By partnering with APS and embracing GEMCO’s innovative solutions, the customer was able to find the key to its blending challenges. GEMCO’s agitator offers a cleaner, faster, and more efficient way to achieve perfect blends.

Gregg Muench is VP of sales & marketing, GEMCO, and George Paffendorf is VP of operations, Advanced Powder Solutions, and VP of process engineering & design, GEMCO. For more information, visit www.okgemco.com.