Applying Powder Flow Analysis to different industries
It is estimated that over 50% of manufactured products are powders at some stage during their production.
These powders will possess a wide range of properties such as consolidation caking, cohesion, and powder flow speed dependence, all of which will impact on their storage and bulk flow.
Many powders can potentially gain strength and cake during processing, storage and transport to the final consumer, causing the formation of lumps and aggregates, or they may be transformed into a caked bulk. This can be very undesirable, causing production delays and lost production, and represents a major product quality defect in the eyes of end-users of powder products. Raw ingredients can be assessed on a regular basis to keep watch on batch and source variation and finished products in powder form can undergo a full assessment to measure the properties (e.g. fully flowing, caking, cohesion) that will be experienced by a consumer or user.
The examples below show industries where powder flow knowledge is known to be of major significance with highlights of academic that has also been published in this field. These are just some application and operation areas where commercial advantage, profit, and product performance within these and similar industries can be enhanced by an improved knowledge of powder flow.
Welcomed by all sectors of the food industry, Powder Flow Analysis allows accurate and objective testing of ingredients, blends and finished products, as diverse as lecithins, flours, coffee granules, drinking powders, sugar, sweeteners, spices, pulses, salt, seasonings, herbs and milk powder.
Objective and repeatable testing combined with ranking of dry powder samples can provide significant opportunities and benefits. These include optimising batch and source selection in terms of cost and quality; the development of best mix formulations; optimising scaling up and process conditions; and maintaining product quality control. Innovative technology provides such data either by measuring and comparing products capable of flow, or by assessing sample behaviour under test conditions simulating in-process or product handling conditions. Best-practice raw material purchasing, processing efficiency, waste minimisation and product quality – before and after storage, packing and transportation – are all desirable for manufacturers. The application of practical powder rheology is a valuable tool for achieving these goals.
Some of the most common powder handling problems arise when conveying from storage silos or bins into production. Often the powder or grain will have been motionless for hours, days, or even weeks before flow is required. Over this time, most powders or granules will compact with the result that far more energy is needed to cause flow than in aerated samples. On the other hand, powders used immediately after transport, which may have involved agitation or more pronounced vibration, will have been aerated and flow more easily than others that have been stored. Cornflour, Couscous, Flour (white), Flour (wholemeal), Oatbran, Polenta, Rice (flaked), Tapioca and Wheatbran.
Cleaning and washing products
As costs are required to be driven down, the substitution of expensive constituents with lower cost powders is an attractive prospect. Although these substitutes may be produced to the same specification as the original substance, they may not necessarily store, convey and process as easily. Discovering this after production of materials such as detergents has started would incur downtime and additional cost. Final product quality may also be compromised.
Nuts, seeds and pulses
In these products, many common manufacturing problems are attributed to powder or granule flow, including segregation, inaccurate filling of packaging, obstructions and stoppages. These in turn lead to machine downtime and defective end-products. Storage, handling, production, packing, distribution and end use can all be negatively affected by common powder/granule flow problems.
Personal care powders
The PFA is particularly welcomed by the pharmaceutical and cosmetics industries as it allows objective testing of ingredients, blends and finished products, from eye shadows and foundations to gels and face powders, baby powder, bath salts, denture cleanser, face powder, foot powder, protein powder and slimming powder. Product development teams can evaluate the flow properties of new excipients, active ingredients and formulations, predicting their behaviour prior to commencing large-scale production. They can also check how new powders interact with existing constituents. This speeds up development time and minimises “trial and error” tactics, especially important when certain ingredients are extremely valuable and may have only been produced in small quantities.
Building and decorating materials
Many common manufacturing problems are attributed to powder flow, including non-uniformity (segregation) in blending, under- or over-dosage, inaccurate filling, obstructions and stoppages. These in turn lead to rejected material, machine downtime and defective end-products. Storage, handling, production, packing, distribution and end use can all be negatively affected by common powder flow problems. These materials include cement, interior filler, plaster, sawdust, sugar soap, tile grout, wallpaper adhesive and paint.
Garden products, agrochemicals and animal feed
Handling and processing powders, particulates and granules is central in product processing, but has traditionally been fraught with problems due to their unpredictable and irregular behaviour, specifically with respect to flowability. With so many raw materials and semi-finished products in powder form, such as bird sand, grass seed, insect food, Nyjer seed, herbicides, pesticides and plant fertiliser, this sector stands to gain significant manufacturing and commercial benefits from improvements in the assessment of powder flow.
The above highlights just a few industries and their typical powder flow issues but the list is exhaustive and also includes such examples as:
Abrasive and fine powders: : Diamond, ceramic, and metallic powders and pastes for grinding, polishing, magnetic recording tapes
Ceramics: Powder and wet mix for extrusions
Energy: Coal and other powdered fuels, nuclear fuel granules
Metallurgy: Iron and steel powders, quartz, ore, sintered powders
Paint: Pigments, fillers, binders (titanium dioxide)
Toner: As used in photocopiers