Assessing Flowability of Cohesive Powders from a Small Sample Quantity

Lead Research Organisation: University of Leeds
Department Name: Inst of Particle Science & Engineering

Abstract

Processing of fine and cohesive powders is very difficult and often marred by inconsistencies in powder flow behaviour which adversely affects plant reliability and productivity. Good examples are in pharmaceutical, fine chemicals and nuclear industries, where dosing and dispersion of small quantities of cohesive powders is technologically very challenging. For instance for drug delivery through lungs the functionality of dry powder inhalers is strongly dependant on flowability of weakly compacted bulk powders. Current test methods for assessing the flow behaviour of powders (unconfined compression and shear cell testing) require a relatively large amount (at least 100 g) of powders. This is undesirable for industries such as nuclear and pharmaceutical due to ionising radiation for the former and toxicity, cost of drugs and lack of availability at the early stages of development for the latter. Furthermore the traditional test methods are not suitable for testing very weak compacts and the packing may be different from that used in the common methods such as unconfined compression and shear cell. Therefore the flowability of the sample has to be assessed in its own container. This research project is formulated to evaluate the analysis of the deformation and flow behaviour of fine cohesive powders at small scales (typically a few cubic mm) and at very low loads by the indentation probe method. An integrated approach is proposed to achieve the goal, which includes experimental work to analyse the mechanical properties of the single particles and bulk flow behaviour and simulation work to relate the bulk behaviour to the properties of primary particles. The described procedure will establish a link between the microscopic and macroscopic behaviour of particle assemblies subjected to compression and will elucidate the circumstances under which the particles form a strong compact. In particular the deliverables are:-a correlation between powder flow function, based on the unconfined yield stress, and indentation characteristics for samples of a few cubic mm;-a validated test methodology for measurement of the bulk yield stress of small quantities of cohesive powders;-an understanding of powder deformation at low loads.
 
Description We have developed a new method for testing the flowability of fine cohesive powders at low applied loads and using a small quantity of powders (less than a gram), hitherto not possible. The work has now been extended to diagnosis of powder caking. In the long term the method and understanding gained through this grant will have a major impact in industry. The International Fine Particle Research Institute allocated generic research funding to this topic to get a better understanding of the underlying powder mechanics for a wide range of powder.
Exploitation Route We are collaborating with the following organisation on further development of the technique:
1. Beijing Food Institute (Dr Q. Chen) on the application of the method to caking of food powders.
2. Freeman Technology, Tewqesbury, UK on flowability testing.
3. AstraZeneca, Macclesfield, UK, on agglomeration of cohesice powders
4. University of Sheffield, UK, (Profs J Litster and A Salman) on undesirable auto-agglomeration
Sectors Agriculture, Food and Drink,Chemicals,Healthcare,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology

URL http://ghadiri-group.leeds.ac.uk/our-research/powder-mechanicspowder-flowpowder-flow-and-flowability/
 
Description Procter and Gamble Newcastle Innovation Centre, Longbenton, and AstraZeneca, Macclesfield, have used the method to diagnose powder instability due to caking. Also DuPONT, USA, have evaluated the method for their powders.
First Year Of Impact 2014
Sector Agriculture, Food and Drink,Chemicals,Education,Healthcare,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology
Impact Types Economic

 
Description Brian Scarlett Travel Award
Amount $1,000 (USD)
Organisation International Food Policy Research Institute (IFPRI) 
Sector Charity/Non Profit
Country United States
Start 06/2012 
End 05/2013
 
Description EPSRC Future Formulation
Amount £1,749,961 (GBP)
Funding ID EP/N025261/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 01/2017 
End 12/2019
 
Description IAA
Amount £40,000 (GBP)
Funding ID EP/K503836/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 09/2015 
End 09/2017
 
Description Invited Research Project Proposal
Amount $108,000 (USD)
Organisation International Food Policy Research Institute (IFPRI) 
Sector Charity/Non Profit
Country United States
Start 11/2014 
End 10/2017
 
Description Travel Bursary
Amount £700 (GBP)
Organisation Armourers & Brasiers 
Sector Charity/Non Profit
Country United Kingdom
Start 03/2010 
End 04/2010
 
Description Travel Bursary
Amount £700 (GBP)
Organisation Armourers & Brasiers 
Sector Charity/Non Profit
Country United Kingdom
Start 03/2010 
End 04/2010