Mixing it up with industrial mixers and agitators
Industrial mixers and agitators are widely used in food processing, engineering, pharmaceutical and water treatment industries to mix or blend fluids, some at high temperatures and with high shear requirements.
The difference between industrial mixers and agitators
Mixers are mechanical devices that allow the mixing of products at low speeds (kind of like your kitchen mixer, just bigger) with a rotation speed of up to 200 rpm Agitators are also mechanical devices, but these often mix products at high speeds (from 200 rpm to 1500 rpm). Mostly, these terms are used interchangeably because both devices perform the same function. Namely, to mix different components to achieve a specific result, whether it be simple blending, crystallization, extraction, or to achieve complex chemical reactions such as suspension or emulsion.
Functions of an industrial mixer or agitator
The blending of miscible liquids (i.e., liquids capable of being mixed to form a homogenous mixture) is a simple operation that blends or combines two or more materials until every drop or particle of each of component is completely mixed or disseminated.
Factors that influence the blending of the components include the horsepower of the mixer or agitator, and the amount of time available for mixing.
Suspension is when the mixing of liquids allows you to suspend insoluble solids in that liquid. Another way of saying this to create the conditions where solid particles do not dissolve, like oil in water, the particles in orange juice or the bubbles in carbonated water.
To choose the correct agitator or mixer to achieve solids suspension, it’s important to know the percentages of solids, particle sizes, and setting velocities (feet per second). Other factors that may influence your choice of mixer include the required ease of dispersion and the type of suspension.
Dispersion is the mixing of two or more non-miscible liquids (liquids not capable of being mixed to form a homogenous mixture) or solids and liquids, into a pseudo homogeneous mass that is stable before separation occurs. Examples of industrial dispersions range from slurries to heavier dispersions such as pigment pastes or caulking compounds.
Some conventional propellors or turbines are suitable for dispersions, but industrial mixers with high-speed impellers that allow high shear and greater agitation are needed to allow dispersion within a reasonable time.
To figure out what type of mixer you need, it’s important to note factors such as the type of dispersion required (liquid to liquid, solid in liquid or gas in liquid), the amounts of liquid or gas required for each phase of dispersion, as well as the viscosity of the final product.
For example, some materials tend to float on the surface of a liquid, whereas others may stick together and resist wetting, which means they require higher agitation to disperse. These and other factors such as the desired micron size of the end product influence the horsepower required from your industrial agitator.
Dissolving generally refers to dissolving a solid in a liquid. In cases where solids are difficult to dissolve or where you need to dissolve solids quickly, you’d need an industrial agitator with higher horsepower. The actual time of dissolution will depend on the materials involved (non-crystalline materials like rubbers, resins and polymers can result in increased viscosity, thus requiring longer dissolution times).
Should the application have the ability to withstand longer dissolving times, industrial mixers or agitators with lower horsepower can be used.
Of course, these are just four of the functions of an industrial mixer and agitator. To learn more about mixers and agitators and how the specific combination of materials can affect the horsepower required, read Part 2 of Mixing it up with industrial mixers and agitators: Function over form.
At Vissers Sales Corp. we provide a range of industrial mixers and agitators. Call us (toll-free) on 1-800- 367-4180 to let our team of experts help you find the right solution for your process.
As your supplier of industrial mixers and agitators in Ontario, we’re here to help you choose, install, maintain, and monitor a variety of equipment. And to answer questions about things you’ve previously tried gone wrong.