In simple terms, particle distribution refers to the size and proportion of particles within a specific sample. The distribution of particles within a material affects its physical and chemical properties. As such, particle distribution helps manufacturers ensure the quality of a material.
What Does “Narrow Particle Distribution” Mean?
When a material has a narrow particle distribution, this means all the particles within the material have a similar size. The particles are more or less uniform, and the term “narrow particle distribution” is often used to describe this uniformity. However, determining the best size distribution of particles depends upon what the material is and how it’s being used. Additionally, the uniformity of these particles will determine how a material will react under various conditions.
Importance of Particle Size Distribution
Quantifying particle size distribution of material helps manufacturers determine whether milling or sieving succeeded in breaking particles down to a uniform size. This is particularly important for bulk dry materials in powder form. Analyzing particle size distribution helps ensure products function as they should, and involves monitoring, control, and investigation of a material’s properties, including its strength or how the material reacts to chemicals.
It’s essential for:
- Material processing, handling, and packaging
- Product development
- Quality control
- Research
The primary methods for determining particle size distribution involve using sieves or laser diffraction.
Pharmaceuticals
Narrow particle distributions are extremely important to the development of pharmaceutical products. The size distribution of powdered particles of active pharmaceutical ingredients helps determine how effective a medicine will be. Uniform size distribution affects the flowability of active pharmaceutical ingredients, along with fillers and lubricants. It’s also a key factor in a medication’s bioavailability, the rate at which drugs are absorbed into the circulatory system. They ensure that the active ingredients reach the right part of the body in the correct concentration and at the appropriate rate.
Inks & Pigments
Incorrect size distributions cause inks and other pigments not to flow well through their delivery device. A finer, more uniform distribution can also help the ink or pigment deliver the same color intensity with less of it required.
Narrow particle distribution in inks and pigments helps determine their:
- Determines appearance, as per glossy or matte finishes.
- Flocculation, which facilitates bonding between particles during processing.
- Hue and tint.
- Transparency of their finish.
- Viscosity, stability, and resistance to weather conditions.
Production issues often result when products don’t have sufficiently narrow particle distribution.
Cosmetics
Ensuring precision in particle distribution is important for manufacturers of products like concealers, lipstick, and moisturizers. Knowing the precise particle structure and dimensions is key to determining safety and performance of products applied to sensitive areas of skin.
Polymers
Plastic pellets used for injection molding processes require a very narrow particle distribution to ensure the material melts at a consistent rate. Very small particles – often referred to as “fines” –melt much more quickly, regardless of the type of resin. When pellets are not uniform, it affects color and other properties of a product, while also affecting the lifespan of manufacturing equipment. When larger particles occur in a polymer, blockages can occur that cause machinery to malfunction, resulting in downtime due to the need to clean, repair or replace components.
Food & Beverages
Particle size distribution impacts the properties of food and drink, including such things as product consistency and taste.
Food products that require a narrow particle distribution include:
- Edible oils and other emulsions.
- Powdered products like coffee, dried foods, and drinks, flours, herbs, spices, and tea.
- Sweetening power of products such as sugar and sugar alcohols
- Suspensions such as peanut butter, whole milk, and certain salad dressings.
- Those that come in pellet form, such as beans, bread crumbs, grains, and pet food.
Petrochemical Products
Engineers sample oil-based products used to maintain industrial equipment, analyzing them to determine the size, structure, and quantity of particles that result from wear and tear. Particle size distribution within oil-based products affects lubrication properties, and thus is an important element in engineering filtration equipment to reduce the effect of contaminants. In the oil and gas industry, analysis helps remove those particles that cause harmful emissions or that may provide useful properties.
Reduction & Distribution of Particles
Reducing the size of particles within a material offers a number of advantages. Smaller particles tend to have more uniform traits and narrower particle distribution. Reducing particle size increases surface area, enhancing colors in pigments as well as how sorbents react. It’s a vital part of processing grains, as it improves digestibility. Measuring how particles are distributed within a material helps manufacturers reduce contamination, or to improve production methods.
Particle Size Reduction Equipment
Various industries use equipment to reduce particle size in material to improve performance. These machines are used in the fabrication of a variety of products.
These include:
- Lump breakers, also called lump crushers or flake breakers, are used to break up material that is clustered or compressed due to transport, production or prolonged storage.
- Hammermills use hammers on a rotating shaft to break down materials and achieve uniform particle sizes, resulting in narrow particle distributions, especially when used in conjunction with air classifiers.
- Fine grinding mills work well for dry and free-flowing materials like sugars or resins, using fixed blades to reduce material into fine mesh sizes via impact into a narrow particle distribution range.
- Air classifying mills combine grinding in a closed circuit with internal air classification to achieve a narrow particle distribution.
While air classifying mills are ideal for milling material so that it has a narrow particle distribution, air classifiers can also be paired with other reduction equipment to achieve similar results. They’re often used with conventional mills for separating and recovering various materials for aggregate production, mining, and other industrial processes.
Air Classification & Achieving Narrow Particle Distributions
Air classification is a means by which manufacturers separate granules or powders through the use of pneumatic air that moves particles with different drag forces. Air classification helps achieve narrower particle distributions for an assortment of dry bulk materials.
Air Classifiers
Air classifiers are machines used in production when material needs to be separated by density, size, and shape. They work by injecting material into a chamber in which a column of rising air then segregates larger and smaller particles. This separation chamber lifts material into the air, where the natural drag vertically sorts particles according to shape and size, used to achieve narrow particle distribution of materials. They’re used in processing large volumes of non-homogenous materials efficiently and quickly, featuring in such applications as cement manufacturing, chemical processing, controlling air pollution, cosmetics making, food processing, and fabricating pharmaceuticals.
Air Classifying Mills
Air classifying mills combine an impact wheel for fine grinding with a built-in air classifier. While simpler air classifying mills only utilize a single particle reduction stage, more advanced models reduce particle size in multiple stages to achieve a very narrow particle distribution.
