Dry coating of powders and grains by high shear mixing | Project Opportunities | PhD | University of Leeds

Funding: External Partner Studentship, providing the award of full academic fees, together with a tax-free maintenance grant at the standard UKRI rate (£19,237 in academic session 2024/25) for 3.5 years.

Lead Supervisor’s full name & email address

Dr Xiaodong Jia x.jia@leeds.ac.uk

Co-supervisor’s full name & email address

Professor Mojtaba Ghadiri: m.ghadiri@leeds.ac.uk

Dr Ali Hassanpour: a.hassanpour@leeds.ac.uk

Dr Wei Pin Goh: w.p.goh@leeds.ac.uk

Project summary

Dry coating of powders and grains (host) by much finer particles (guest) is widely used in food, pharmaceutical and battering manufacturing technologies to impart desirable functional characteristics, such as controlling bulk cohesion and thereby improving flowability and tabletting, controlling drug release in dry powder inhalers and flavouring of crisps.  The operation is currently an art and the practicing engineer relies heavily on past experience and new experimentation.  Process optimisation is often very costly and time consuming, due to the diversity of material characteristics, lack of understanding of what goes on inside the equipment during processing, interactions of the materials with the environment, process dynamics and scale-up. Dry coating depends on many factors, in particular particle size, shape, density, interparticle adhesion and medium fluid drag. This project aims to put the operation of dry coating by high-shear mixing on a firm scientific base by a two-pronged approach: modelling by the Discreet Element Method and experimentation by characterising single particle adhesion and bulk mixing.  Interparticle adhesion will be characterised by the Drop Test Method developed at the University of Leeds. Bulk mixing will be studied using three types of mixing equipment, tumbler, impeller-driven mixer and intense high shear mixer. The systems to be investigated will have a dual focus:  one on the fundamental engineering science of dry coating by high shear mixing and the other on its application to powders of interest to the industrial partner. Fundamental research involves the use of surface-modified glass beads (by acid-washing to make it hydrophilic, and silanisation to make it hydrophobic), and the use of both hydrophilic and hydrophobic glidants such as fumed silica (e.g. AEROSIL®) calcium carbonate and zeolite. Specific applications are to be defined by the industrial partner.

Please state your entry requirements plus any necessary or desired background

A first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline

Subject Area

Chemical Engineering, Manufacturing, Mechanical Engineering

Keywords

Calcium carbonate, discreet element method, drop test method, dry coating, fumed silica, high-shear mixing, zeolite

Advert information