Pump consultation

EPSRC Future Manufacturing Research Hubs 2016: The Powder Utilisation and Manufacturing Portal (PUMP)

Exploring Industry Challenges for POWDER PROCESSING COMPANIES and EQUIPMENT MANUFACTURERS

February/March 2016

Abstract

This paper documents an industry consultation study undertaken in early 2016, across a wide range of UK base companies and multinationals with significant UK operations, to identify themes and detailed requirements for scientific and engineering research needed to support the medium to long term future of the parts of the UK manufacturing economy that depend on processing of powder and bulk solid materials. Powders are directly used in most manufacturing industries, and are at the base of many emerging manufacturing techniques.

From the consultation, a proposed integrated programme of research has been derived and this is detailed.

The inputs have been anonymised, and in places the detailed records of discussions have been redacted, at the requests of the industry participants to protect their commercial interests. Should readers wish to obtain access to the more detailed records then applications will be considered.

This paper consists of 3 parts:

Description of the study – Objective, Method, Sample Selection, Anonymisation
Records of meetings
Distillation of research themes

1. Description of the study

1.1 Objective To identify the current and future challenges and opportunities in industry with powder processing, and distil the fundamental and applied research themes which could deliver benefits in the medium to long term to enhance the competitiveness of UK industry in terms of cost, quality and new/unique product offerings. To include both high volume and high value processes, including those which are established and those which are emerging.

1.2 Method A number of "focus group" meetings were held involving powder processing and powder processing equipment companies across the size range from start-up SMEs to the largest multinationals. Questions were posed to draw the participants on the problems, opportunities and needs which if met, would enhance their UK manufacturing in the future, and also their vision of where manufacturing might go in the future and what would help them to make the perceived future opportunities a reality. In some cases meetings were held on a 1:1 basis due to the limitations of diaries of key personnel from the companies An overview of current, emerging and prospective techniques for analysis and modelling was given, and the mapping of these onto the identified needs of industry was discussed, to try to find the areas which offer the biggest prospect for improvement of manufacturing competitiveness through new research in the medium term. Free discussion was encouraged for the main part of the meeting, with a facilitator acting to ensure a fair share of the floor for all participants and also to ensure all aspects of the questions were explored. Subsequently the common threads were identified and divided into proposed themes of research, and these were shared with the participants for comment and feedback.

1.3 Sample selection It was considered important to ensure that the companies making the input have a realistic prospect of embedding and exploiting the results from any research stimulated by the consultation. Therefore, companies were identified (from a wide range of sectors) that have a strong track record of bringing collaborative research with university partners to implementation, and these were invited to participate. Five industry sectors were focused upon, previously identified in consultation with the industry associations (SHAPA, MHEA, IMechE) as being heavily dependent on solids handling both for current products and future product development prospects:

Food (the UK's largest manufacturing sector and the largest buyers an users of manufacturing equipment associated with powders and bulk solids)

Pharmaceuticals

Engineering products (Automotive and Aerospace with particular reference to Powder Metallurgy and Additive Manufacturing)

Chemicals and Minerals

Equipment manufacturing, design technology companies, engineering and consulting houses

1.4 Anonymisation Companies are identified by number, size and function. The raw data is available upon request subject to data protection protocol.

2. Minutes of meetings

1^st Focus Group meeting 1 February 24

BF – Co. 1 SME Manufacturer or rotary valves

Equipment selection and design - RV specific

Powder Flow & physical behaviour - conveying in humid atmospheres for hygroscopic materials, when these two points cannot be changed. how to predict the problem, and engineer the conveyor to cope with these! Ideas needed! Coating on inside of the equipment - what to do to the material to reduce its hygroscopicity, - how to select anti-caking aids (need a wide range of different chemistries to avoid contamination objections); or to the surface - still getting build up on coated equipment - How to ensure we can get a mechanical solution rather than use a coating. fundamentals of this? Effect of flow (turbulence etc)

Rotaval wishing to engage with both some core (underpinning ie core funded) and also company-specific (company funded) research/development activities

WW - Co. 2 SME Supplier of granulation expertise

Granulation - WW granulation and powder processing consultancy. - plan a 1:1

WW - Co. 3 SME supplier of conveying and handling equipment

Better understanding of material breakage during conveying - design rules to choose conveying technology for the material breakage behaviour

Segregation likewise

Aeration and flow

Needs:

1. A quantified understanding of material breakage during conveying vs. conveying technology

2. A quantified understanding of mixture segregation during conveying vs. conveying technology

3. A cost effective quantifiable instrument to measure powder fluidisation potential, ideally sub £5k. (Currently on the market you have the Freeman Powder Rheometer at ca. £35k and the Revolution at £15k)

NM – co. 4 SME manufacturer of sieving and filtration equipment

Predicting rate through sieve meshes

Effect of cohesion, static and humidity on sieving

Use of electrostatic control

Russell to contribute in kind - kit/trials

IB – Industry association 1 (115 members in manufacturing and supply of solids processing equipment

Need for a more integrated framework of classification of materials for processing including isolating their problems (hygroscopic, cohesive, friable etc). Currently available methods for characterisation do not necessarily give whole picture - and there is poor linkage between the output of the characterisation measurement and plant design. Also, how to cope with the difficulty that sometimes these characteristics reinforce or oppose each other in terms of plant design requirements.

2^nd Focus Group Meeting 2: 25 February

MT – co. 5, Commercial suppliers of design and analysis systems

Challenges in powder handling - in most chemical processes.

Desire to develop fundamental understanding of powder behaviour (single particle, particle/particle interactions

Modelling - of particle/powder design and powder flow, then leading on to effective process design and supporting appropriate equipment selection and design

Engineering of the particles for physical properties - including but not limited to granulation then milling prior to compaction; also encapsulated product

Design primary particulates (especially NCEs) especially actives for easier direct compression - understanding of what works here and how to get to it

Surface build-up, contamination - what causes it and how to stop it happening - how a process design approach can be used to minimise it; coatings; material modification; identifying and predicting this in advance

Predicting flowability from formulation and from characterisation of a small sample, and therefore selecting equipment - especially metering in pharma, nuclear, food

Britest would like to accommodate powder behaviour issues in existing tools for design and selection of equipment - knowledge based and characterisation based

Offering in-kind support

Common interests identified – requirement for underpinning research

Material characterisation methods to identify problems in advance - surface build up, fouling and blockage, interlocking of extreme shape particles static charging,

Better linkage between bench scale char ptests and formulation, and behaviour in a process

Electrostatics - better understanding of how particles charge and how the charge affects their behaviour in processing

Sensitivity to humidity - based on knowledge of chemical and physical structure of the particles

RM – co. 6, SME manufacturer of power mixing, grinding and blending equipment and systems

Toll processing - sub mm down to 5 micron, mainly powders for polymer composites. Particle size & shape both important for performance and manufacturing process repeatability.

Grinding and milling, predominantly air jet milling.

Primary issues / concerns;

Breakdown / fracture mechanisms, particle shape and attrition; how a particle will mill based on its structure;
Influence of static charge on classification and processing / handling - especially in sub 5 micron range (MIE below 3mJ!) to avoid explosion hazard. How will it charge and how will it affect classification - use of CFD;
Prediction of "in process" powder behaviour - prior to size reduction and classification (polymers, activated carbon and others) -
Optimization of throughput vs. cut size and sharpness. How to improve this balance.
Reduction of equipment wear through process design - why does wear concentrate in certain areas

Modelling and understanding physics of air jet grinding and classification

Better exploitation of existing characterisation methods for selection of equipment

PA/CE – co. 7, start-up SME developing new, low energy drying systems for commercialisation

Drying of coal, biomass and other materials using reduced energy compared with thermal methods

Blending biomass and coals

Blockage and deposition of materials inside equipment processing

How to handle and package fine powders to deliver - including size enlargement after milling and drying without excessive energy consumption - direct compression (low energy briquetting)

Material build up and blocking - based on knowledge of material chemistry and properties, and methods to avoid it

TP – co. 8, large company providing processing systems construction and equipment for pharmaceuticals manufacture

In the Pharmaceutical environment we see an increase in the number of materials ( NCEs) which have been produced with appropriate chemical / pharmacological properties but which are potentially challenging from a materials handling perspective. Typical issues are low bulk density, irregular structure, high resistivity, sensitivity to shear , poor flow properties, high variability between batches and very high value .

Frequently opportunities for better particle engineering may be limited.

The issues / goal for our businesses are

Ability to apply predictive testing using very small quantities of high value active in order to screen for / identify potential future processing problems

Ability access / apply multi-physics modelling of multicomponent systems for example with capability to account for agglomeration / attrition / stress sensitivity / tribocharging effects.

In general strong alignment with comments from Mark at Britest

3^rd Focus Group meeting 26 February

BM – co. 9, large multinational company providing characterisation instruments for powders and liquids

Characterisation aspects - so many customers not yet at first base - need to get powder users to take more notice and care

Standard template needed for categorisation and classification of powders - to make it more accessible to users

Guidance on what are the characteristics they need to know, in relation to their materials and processes?

Are there fewer basic parameters that we could use to "Unlock" the knowledge of the fundamental forces leading to the observed behaviour - VFL

"helping customers to get to a starting position in understanding their powders"? How to get something done to get equipment in chemicals and minerals sectors the path? Quick guide - expert system web based? Often people don't recognise they have a risk due to powder behaviour - don't know what they don't know. Simple mental model to sketch out in relation to "the six things that might happen"? Britest "rich pictures" approach. Web based approach to get started - doesn't give people the understanding but helps guide them quickly to the risk area.

JC – co. 9, SME providing wear resistance solutions for solids processing

Protecting process plant from wear and attack; how long will it last?

Currently use past history, experience and feedback - but problem is lack of knowledge of process conditions. Practical test methods - variations in materials and processes - need some more knowledge of how the process context affects it.

DEM modelling - high cost and shows only a starting point - what happens as the process condition varies?

TP - co. 10, providers of pharmaceutical manufacturing equipment

Inability to classify and identify real behaviour of materials and how they will behave in a process - akin to Geldart. What characterisation is important? What are "fundamental properties" and what are "composite behaviour"? How does the process context and processing. Different batches and sources of "the same" material behave very differently in the same process – what causes this?

How much memory is inherent in different particle materials - how much resentment it contains within itself - how and why do they remember these processes - energy stores and memory mechanisms?

Need screening tests to show up what are the likely important characteristics for a given processing route and also

Pharmaceuticals for bio-origins - only a very few grammes available - what can we do with small samples

How many words do eskimos have for snowflakes >>>>> Creating a language to describe materials

Answering not only does it flow but WHY does it flow / not flow in a certain way

Use of "Multivariate maths" to build composite classes which allow "surrogates" for testing

What does the data set need to contain to represent the important aspects of behaviour? Novel math methods to build composite picture of classification of behaviours, based on wide data set. Take range of materials with widely differing behaviours -

Why does "the same material" vary so much in its behaviour? Look behind the behaviour to find out why. Eg response to environmental conditions.

Link to other networks … W/W and EU ( MC proposals for powder in progress)

Novel materials / novel properties / novel applications ….eg nano

Cannot easily get useful samples from mixing - how to understand the level of variability of mixedness through vessels and what causes this to change?

Continuous manufacture - asseming small number of particles to give precisely the needed mix locally. "Crowd mechanics" - getting the individual particles to behave well to get the bulk to behave well - powder engineering for anti segregation, and other problems

EM – co. 11, SME suppliers of conveying and processing equipment for bulk solids in all sectors

Characterisation - methods needed to cover aspects of material behaviour in different process states (loose, dense, in liquid etc - a quicker way to get to know a material prior to more in-depth characterisation work. Unifying the many characterisation processes to join up their use

Where material varies in density etc how does it vary with time and process

Mixing and size reduction are industries that have "evolved" - need more predictive modelling for optimise, more observation and development of classes and selection of equipment

What does "well mixed mean" - scale of scrutiny - how and in what scale do we analyse at in practical terms?

PF – co, 12, medium company providing solids processing systems mainly to minerals, chemicals and allied sectors

Effect of particle shape on its behaviour

Characterising the particles in as many different ways as you can - an integrated approach

Getting the customer to understand the importance of good characterisation at the outset.

"500 different types of carbon black" - why do they vary so much and how to deal with this?

Declared support

Looking behind the behaviour into the causes of the behaviour - not just "does it flow" but "why does it flow?"

Predictive tools

Memory of powder - goldfish or element? number of energy stores or states - also rate of change (relaxation) time and context dependency

MA – co. 13, SME Providing air movers for industrial applications including conveying and processing of solids

Are there several KTPs that could be done together - gearing by working together. Aligning existing KTPs under PUMP umbrella

Will offer support

IP arrangements for network to be put on the table early.TP to help MB develop principles

4^th Focus Group meeting 1 March 2016 14:00

IC – co. 14, Large multinational providing grinding, classification and other processing equipment and complete systems for solids in pharmaceutical, chemicals, food and minerals sectors

"Natsier" materials - need to model with less trialling

Characterisation of processing behaviour from very small samples - eg grammes; how representative just a small sample - the "memory" of history of powders - what risks in scale-up

Feed in and out of mills etc. - how does this vary with time and temperature

How does a material break down - indexing of materials by fracture habits, effect of shape, effect of grinding pressure or impact velocity, particle-particle collision. Extension of known behaviour of single particle crystals into bulk behaviour. Benefits - less trials of nasty materials roadmap approach a grinding challenge - to help steer critical trials. Compaction - particle shape effects

DS – co. 15, Multinational providing solids storage, handling an feeding systems in petrochemicals, plastics, minerals, pharmaceuticals sector

Improved methods of equipment design and selection - poor understanding amongst users (and some suppliers) about importance of venting - air interaction!

Variations in temperature and humidity - effects on handling and flow in feeding and dosing - wider characterisation that gives information about effect of a range of conditions

Need a much wider appreciation of basics of bulk solids handling amongst equipment users (for writing specifications etc)

Need for engineers who understand engineers with BSH knowledge - should be in mechanical engineering training - need to reach out to wider educational sector

Need handling properties from materials suppliers - outreach needed

Configurational modelling tool to take elements in a powder processing chain and automatically produce the questions that need to be asked about rates, materials properties etc. relative to each stage. UK is far behind other parts of the world in terms of the information furnished regarding materials properties and requirements related to plant parts.

Blends and ATEX - handling blended products and explosivity issues - testing tends to be on individual materials?

Level switches - reference tool to aid selection based on material properties, process context - independent review of the pro's and con's based on user experience

IB – co. 16, Multinational providing separation equipment for gas/solids and gas/liquids processing in all food, minerals, pharmaceuticals, nuclear and other sectors

Adhesion and cohesion properties, release from surfaces - especially at high temperatures - due to difficulties of not being able to characterise - and/or effects of these predictively modelled. User of powders to make sintered filters (metals, plastics) - understanding structure and strength and filtration performance of high-voidage sintered structures (shape, size distribution, compaction stress, sintering). Relationship between sintered structure and filtration performance, also mechanical (structural and fatigue) strength.

5^th Focus Group meeting 8 March 2016 1-to-1 with M Bradley

CB – co. 17, SME providing mixing equipment for powders and powders/liquids in all sectors

Mixers - aim to increase export sales

Continuous development of mixers.

~Need protection of IP -

When is a batch fully mixed? How to observe when it is mixed - in real time - without using NIR (unsure of issues where there are blades present)

Current method is test and sample empirically – but this takes a week

Choosing what type of mixer - including liquid additions - series of tests and experience of "similar" materials - but based on what experience (flow properties - by angle of repose (gives good feel), psd and bd)

Blending time fairly accurate from similar materials - but needs to be tested on pilot plant - then scaling up to bigger size is quite accurate for power and time

get set of results in real time -

Variation in "the same" materials - guarantee based on materials received - consistency in input ingredients needs to be better

Mis-selection of mixer type or time often due to increased fines, moisture uptake,

Putting a lot of shear into powders heats them - so turns from free flowing into sticky mass or balls

Characterisation of powders in advance needed to help selection and power assessment - bd, psd, flow properties particle breakdown (desired or undesired),

Understanding optimisation of compromise between high energy ip and rate for effective and fast mixing versus

Make users more aware of best practice

Reaction during mixing

Pastes and spray coating in mixers - enrobing without granulation and also granulation in mixers.- all done empirically

Top analysis of powder and analysis of the mixedness - comparison of analysis methods (modelling, PEPT, NIR etc).

Need in-house short courses

6^th Focus Group meeting 10 March 2016 1-to-1 with M Bradley

MH - co. 18, multinational developer, manufacturer and supplier of metal powders for additive manufacturing

Caking of powder in annealing – predicting and controlling strength

Understanding and predicting flow properties better

Need to be able to understand relationships between manufacturing methods, raw materials, resulting behavioural properties and effect of these on the manufacturing of the finished products

7^th Focus Group meeting 12 March 2016 1-to-1 with M Bradley

GM – co. 19, very large multinational manufacturer of bulk and speciality chemicals for all industry sectors

Need for better understanding and easier to use models for breakdown properties of particles in handling and processing – existing models too difficult, expensive and time consuming to use

Need much better engagement of practitioners in industry with leading work in academe

Better methods needed for isolating likely problems due to process or raw material changes

8^h Focus Group meeting 8 March 2016 1-to-1 with J Heng

GZ - co. no 20, large US based manufacturer of pharmaceuticals which sponsors significant UK research

Overall:

Very much interested in the activities being proposed for PUMP
Already working with some PUMP partners and see this extending on from that interaction and collaboration.
Will be able to provide in-kind contributions in the form of membership on steering panels, direct involvement in projects, lab access, internship placements for students and/or postdocs involved within pump, supply of material, etc.

Current challenges and areas of interests:

Amorphous solid dispersions – this is an area which is not currently looked at in detail within PUMP, as it appears that our focus is on crystalline solids. Is this the case and will PUMP include non-crystalline samples (this is also relevant to non-pharmaceutical industries)
The use of new processing technologies for improved dispersion/mixing. One such example cited is acoustic mixing. This also extends to active mixing with the use of nanoparticles to improve flowability of powders – eg SiO2 with varying surface chemical functionality.
As an industry, there is a move towards dry powder processing – for example direct compression and roller compaction instead of wet granulation approaches.
However, there is still a dire need to understand the role of water in manufacturing. It is necessary to account for the impact of water on powder flow, mixing, compaction, etc. Water is ubiquitous and present everywhere.

9^th Focus Group March 2016 with M Ghadiri

5 multinational manufacturers of pharmaceuticals participated, all of whom have significant UK manufacturing operations (companies nos. 30, 31, 32, 33, 34)

All intend to maintain and keep up to date their UK manufacturing operations for the future, including new types of products and new manufacturing methods.

The detailed notes of the meeting have been withheld for commercial confidentiality so the following is a compilation of the challenges identified and needing research to solve.

Generally, the pharmaceutical manufacturing industry deals with a very wide diversity of organic-based drug substances. During their development, frequently there is only a very small quantity available and their particle properties are largely unknown. So the challenges facing this industry can be summarised as follows:

General challenges requiring ground breaking research:

Drug substance manufacturing process development and product formulation development have to be carried out with limited amounts of drug powder.
There is therefore a great need for development of material characterisation tools based on small quantities both in-line and off-line.
In view of limited patent life of a new drug, development timelines should be as short as possible. This requires advanced understanding of particle science and engineering, enabling predictive powder behaviour in process equipment.
The interactions between particle structure, material properties and processing are known to affect performance, but are largely unpredictable.
Equipment type affects product characteristics, but the underlying mechanisms are not understood.
Effect of production scale on properties needs to be predictable.
There is a need to develop predictive tools for processability and particle properties.
Can manufacturability of new drugs be assessed in very small scales (mg range, either experimentally and in-silico)?
How can we develop six-sigma quality for powders as we have today in electronics industry? Can moving to continuous processing resolve the performance and processing variations?
What are the challenges in continuous processing? For example, are the required sensors available for automatic process control?
What new sensors need to be developed for fast online measurement, e.g. granule density?

Specific process operations requiring more understanding:

Can milling behavior be predicted based on input material properties?
In dry granulation-how can/should we improve the manufacturability to avoid common failures, e.g. stickiness, unwanted attrition, insufficient powder flow (technique/formulation, experimentally/in-silico)?
In wet granulation – interaction between materials attributes and process parameters that influence granule properties and subsequently compaction behaviour, e.g. evolution of structure as affected by the process and material properties.
Direct compression is of great interest to pharmaceutical industry. How can/should we improve to avoid (well known) downsides with this process, e.g. homogeneity, segregation during blending/storage/transport, sticking during compaction, etc. (technique/formulation, experimentally/in-silico)?
Ordered mixtures (particularly applicable to dry powder inhalers): what is the optimal blending to achieve homogeneous and stable ordered mixtures?
Much better ability to predict caking, segregation and electrostatic problems is required.
Powder characterization equipment – better, lower cost, more comprehensive and easier to use methods needed.
Filling small amounts (10 to 20 g stick packs) reliably and accurately is a problem, due to issues with flow and static charge. This needs to be looked at in depth.
Prediction of caking during storage/transport - predictive model taking into account all variables (T, t, pressure, RH, etc). Caking remains a problem in bags during storage & transport, in screw feeder tube (High temps & Humidity's) and in equipment generally causing clean down issues – better understanding of the factors involved is required, and more options to reduce the problem
Sugar reduction / making sugar healthier and salt reduction requires ingredient substitution. Models needed to reduce the risk to manufacturing when making these changes.
Better linking is needed between lab measurements and plant performance, such as controlling flow rate of powders, calibrating loss in weight feeders, or predicting/optimizing/ tuning the manufacturing processes
Predicting powder flowability issues in the factory – based on formulation changes; methods needed.
Methods needed to predict powder behaviour from chemical and crystalline properties, to identify those that will cause flow or build up problems
Adhesion of particles to surfaces (where desirable to product or undesirable to equipment) needs to be better controlled and predicted - reducing clean down time, avoiding need to over-dose
Strong desire to "push the barriers" on reducing or coping with powder flowability problems, segregation, dust and adhesion to increase the range of powder blends that can be developed (wrt sensory function). Both smarter formulation to make the materials less susceptible to the problem, and improved process design to reduce the tendency of the process to stimulate the problem.
Effect of particle size of sugar on the intermediate and finished products (physical and sensory) – better understanding and models required.
Processing of powder blends – issues with flowability and segregation by particle size leading to; variations in product density, downtime and waste need to be controlled better

10^th Focus Group meeting 8 March 2016 with C Sinka

CD – co. no 21, UK based technology provider in metals processing with global operations

Current challenges:

Modelling/prediction of powder performance
Integrity of components, manufacturing, quality control
Densification
Characterisation
Coating/surface engineering
Recycling

Specific interest in additive manufacturing:

Powder handling aspects
Characterisation of flow, particle size distribution etc
Selective laser melting, depositions

11^th Focus Group meeting 25 February 2016 with R Berry

4 multinational manufacturers of foods and food ingredients participated, all of whom have significant UK manufacturing operations (companies nos. 26, 27, 28, 29)

The detailed notes of the meeting have been withheld from public view at the request of the participants, for reasons of commercial confidentiality. The following is a compilation of the challenges identified and needing research to solve.

Powder characterization equipment – better, lower cost, more comprehensive and easier to use methods needed.
Filling small amounts (10 to 20 g stick packs) reliably and accurately is a problem, due to issues with flow and static charge. This needs to be looked at in depth.
Prediction of caking during storage/transport - predictive model taking into account all variables (T, t, pressure, RH, etc). Caking remains a problem in bags during storage & transport, in screw feeder tube (High temps & Humidity's) and in equipment generally causing clean down issues – better understanding of the factors involved is required, and more options to reduce the problem
Sugar reduction / making sugar healthier and salt reduction requires ingredient substitution. Models needed to reduce the risk to manufacturing when making these changes.
Better linking is needed between lab measurements and plant performance, such as controlling flow rate of powders, calibrating loss in weight feeders, or predicting/optimizing/ tuning the manufacturing processes
Predicting powder flowability issues in the factory – based on formulation changes; methods needed.
Methods needed to predict powder behaviour from chemical and crystalline properties, to identify those that will cause flow or build up problems
Adhesion of particles to surfaces (where desirable to product or undesirable to equipment) needs to be better controlled and predicted - reducing clean down time, avoiding need to over-dose
Strong desire to "push the barriers" on reducing or coping with powder flowability problems, segregation, dust and adhesion to increase the range of powder blends that can be developed (wrt sensory function). Both smarter formulation to make the materials less susceptible to the problem, and improved process design to reduce the tendency of the process to stimulate the problem.
Effect of particle size of sugar on the intermediate and finished products (physical and sensory) – better understanding and models required.
Processing of powder blends – issues with flowability and segregation by particle size leading to; variations in product density, downtime and waste need to be controlled better

12^th Focus Group March 2016 with R Farnish

SB – co. no. 22, leading multinational steelmaker

Company Seekins to increase production rates through optimisation of the current process. Reducing down time is a major requirement. Pipeline/chute wear is a major problem which is not well understood or predictable at the moment. Areas where research would be of major interest include:

* influence of particle size distribution on wear rates

* influence of variation in particle properties on wear rates (contaminants)

* prediction of changes in pneumatic conveying characteristics due to changes in bulk properties

* influence of particle size distribution/properties on burn performance

* blending behaviour for variable input material

These could take the form of simulations/modelling backed up with bulk scale activities

MM – co. no. 23, leading multinational metal powders manufacturer with leading product development

Challenges current and forseen:-

* improved formulation to reduce segregation of metal powder blends

* improved understanding and prediction of die filling performance

* need to have models and science to develop particles engineered for reduced segregation / improved die filling

TJ – co. no. 24, leading manufacturer of nanopowders including pigments

* Particle engineering to reduce dustiness (establishment of particle strength sufficient to reduce generation of fugitive material/dust, but weak enough not to impair subsequent comminution to a powder at low stress).

* Poor discharge behaviour for cohesive powders needs to be better understood in relation to complex processes

SN – co. no. 25, Leading multinational manufacturer of cement

Requirements:

* Improved understanding of powder flowability in relation to bag filling

* Reduced dust generation during filling (bags and tankers)

* Adoption of technologies to optimise filling operations

* Scope for better prediction of equipment wear – extended service life

* Reduced energy consumption in process equipment

3. Identification of common themes of research need articulated by industry

Modelling approaches

Early stage design challenges

Process design and structure is often set at an early stage when little information is available
Need for models and structured methods for approaching equipment selection and design that can be run with low expense and incomplete information - especially at initial design stage. Need for quick way to isolate risk areas that need much more in-depth looking at (hi-fi modelling).
Need configurational modelling tool to take elements in a powder processing chain and automatically produce the questions that need to be asked about rates, materials properties etc. relative to each stage. UK is far behind other parts of the world in terms of the information furnished regarding materials properties and requirements related to plant parts.
Need for integrated models through the process chain that will join up the parts and capture the tendency of a powder to carry forwards a "memory" of what it has been through
Use of novel techniques (maybe multivariate maths etc) to allow surrogates for testing

Multi-scale linkage challenges

Need to understand what are the fundamental properties of particles and materials that make up a powder, and what are "composite behaviour"

Can we identify fewer basic parameters (that we can measure and quantify) that will unlock the knowledge of the fundamental forces leading to observed behaviour?

How does crystalline structure and single particle breakage habits relate to bulk milling behaviour?

Uncertainty issues

DEM very expensive and time consuming - and only gives a snapshot of one idealised case - what happens with realistic range of process and material variations?

Need to cover risks in scale-up

Design processes

As above in terms of need for low cost easy to use models

Link through from modelling of particles/powders and their design, to effective process design methods

Desire to accommodate powder behaviour issues in existing tools for design and selection of equipment (Co. 5)

Need means for system designer to quickly find out what he doesn't know – Co. 5 "Rich Picture" approach

Need to enable people who are not experts and don't want to be experts, to access and use methods that will control the technical risks

Better linkage between bench scale tests and behaviour in a process

Need easy to use low cost methods to determine what are the relevant powder characteristics for a given proposed process route - investigation needed of processes to determine what are data sets needed to represent the important aspects of the powder's properties

Inter-particle bonding

Caking and sintered structures

Strength (and fatigue strength) of structures made out of sintered powder – co. 16 (filters), co. 18 (cakes of annealed material) - effect of PSD, compaction, sintering conditions

Mitigating caking

Avoidance of unwanted caking due to humidity and other effects; how to choose anti-caking agents - wide range of alternative chemistries needed to minimise objections to contamination

Granulation

Predictive models - effects of conditions and materials

Surface coating, adherence and contamination

How to choose surface coatings

Predicting deposition and fouling in advance of building the plant, and methods to avoid - especially wet and sticky particles. Prediction from small sample tests but also knowledge of chemistry, particle size and shape, moisture content

Release from surfaces especially at high temperature

Particle breakage

Quantified understanding of undesired material breakage during conveying versus conveying technology, and design rules to judge the acceptability of different conveyor types in early stage design

Breakdown and fracture mechanisms in relation to deliberate size reduction - effect of particle shape, and internal structure

Understanding and modelling physics of particle breakdown in air jet grinding

Segregation and separation (undesired/desired)

Quantified understanding of segregation during handling versus conveying type, and design rules to judge acceptability of equipment and likely problems in early stage design

Predictive models needed to allow powder blends to be engineered to be less segregable

Undesired dust elutriation leading to mess

Means for predicting likely rate of flow through sieve meshes - effect of cohesion,. static charging and humidity

Understanding optimisation and throughput versus sharpness of cut in mill classification, how to improve the balance, need to model this

Flow

Effect of aeration on flow - for equipment design (air injection to aid flow, settlement to prevent flushing)

Effect of extreme shape particles eg biomass feedstocks food and pharmaceuticals also

Need for a cost effective quantitative instrument to measure powder fluidisation/aeration/ flushing potential (sub £5k)

Flow effects in feeding milling processes

Better understanding needed about what it is that determines how well a powder will flow

Mixing and blending

Better predictive modelling needed to help selection of equipment type, power, duration

What is "well mixed" - scale of scrutiny needed - how and in what scale to analyse it in practical terms? Cannot easily get samples from mixing to confirm mixedness so need to be able to predict it confidently

Other powder behaviour issues

The "memory" of powders - what happens in one process affects the behaviour of the powder in the next process (co. 10) - the "resentment" that the powder carries with it because of what you have done to it! Energy stores and states?

Why does "the same" material vary so much in behaviour? Environment, processing . . . ?

Effect of particle shape on behaviour

Compaction

How to design primary particulates (especially new chemical entities) for easier direct compression - what works and how to produce it!

Cracking and density variation

Pressing sequence and tool design

Post-compaction performance - dissolution, disintegration, strength - links with caking

Size enlargement by direct compression after processing

Wear

Current predictions use past history, experience and feedback, practical tests are available - but unpredictable differences in material and process conditions change the result

Characterisation

Need to apply predictive testing to very small quantities of high value active to identify potential processing difficulties

Methods that give meaningful measurements of how powders behave in wider range of different conditions - dense, loose, fluidised, in liquid etc

Where material varies with time and process - predicting how much it will vary

Need means to identify and classify material in terms of potential processing problems, based on simple approach (akin to Geldart for fluidisation)

Need a more integrated framework of characterisation for processing especially identifying likely problems (hygroscopic, cohesive, friable etc) to give a more "whole" picture

Need better linkage between available characterisation techniques and plant design that can balance opposing powder behaviour requirements

Training issues

Many powder makers and users very far behind the current state of the art - need to reach out to more potential users with latest opportunities for characterisation and design

Need more mechanical engineers that come into the business to be trained in powder processing - must reach out to wider range of mechanical engineering courses

Improving industry practice

Need more information about materials from those wanting to buy process plants

Need those who write specification in user companies to be better informed on powder processing and handling issues

Other issues

Need more joining up of research efforts, KTPs etc for sharing of learning and benefits. Effective network required to facilitate this.