An investigation into the kinetics of liquid distribution and growth in high shear mixer agglomeration

Knight, P.C.; Instone, T.; Pearson, J. M.; Hounslow, Michael J.

doi:10.1016/s0032-5910(98)00031-x

Cited by 149 publications

(48 citation statements)

References 19 publications

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“…For instance for the granulation of 120 g MCC in the Mi-Pro and an optimum L/S ratio of 100% a liquid addition rate of 10 ml/min has been obtained. As shown by Knight et al [15] a gradual liquid addition leads to a more uniform distribution of the binder.…”

Section: Binder Propertiesmentioning

confidence: 84%

Wet granulation in laboratory scale high shear mixers: Effect of binder properties

2011

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a b s t r a c t Keywords:High shear mixer granulator Torque curves Work of adhesion Viscosity Scale-up The effect of binder properties on torque curves, granule growth kinetics, wet mass consistency and dry granule strength has been investigated in this study. Granulation runs have been performed on a fine cohesive microcrystalline cellulose powder (Avicel 105, d 50 = 20 μm) in two types of laboratory high shear mixers: a MiPro high shear mixer using a 1.9 L bowl and a 6 L Diosna high shear mixer. Binders used included ultra-pure water and solutions of varying concentrations of PVP and HPMC allowing us to cover different values for parameters like viscosity and work of adhesion. Torque curves recorded during granulation are found to allow good control of the process. Optimum liquid requirement for granulation has been found to vary with binder type and decrease with increasing viscosity while granule growth kinetics has been found to be to be related to the work of adhesion for low viscosity binders. Granule strength has been evaluated for wet granules by the means of wet mass consistency measurements on a mixer torque rheometer and for dried granules by means of uniaxial compression tests on a Texture Analyser mechanical testing machine. For low viscosity binders both wet mass consistency and dry granule strength have been found to depend on the work of adhesion. For high viscosity binders higher wet mass consistencies but lower dry granule strengths have been observed. Granulating on the larger 6 L scale has shown that constant impeller tip speed offers good agreement in terms of mean granule size however granule size distribution seems to be scale dependant.

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Section: Binder Propertiesmentioning

confidence: 84%

Wet granulation in laboratory scale high shear mixers: Effect of binder properties

2011

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“…The size of the granules has then been measured. The porosity and the binder content of the granules have been measured using a Pycnometer [19] and the method discussed in [20], respectively. The granulation data are very difficult to model because of (i) the nonlinear behaviour, (ii) the significant effect of the interactions among the input variables, (iii) the uncertainty in the measurements, and (iv) the sparse and limited data.…”

Section: Experimental Workmentioning

confidence: 99%

Predictive modelling of the granulation process using a systems-engineering approach

2016

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“…Different binder addition methods are known to affect the granulation process. Knight et al (1998) used a pouring system for binder addition in a high shear wet granulator and found this would result in the formation of large coarse granules. The initial wetting and nucleation stage is generally considered to be one of the most important aspects of granulation and spray nozzles are usually preferred as they produce a controlled nucleation stage resulting in a more controllable granule size distribution (Iveson et al, 2001).…”

Section: Granulation Processmentioning

confidence: 99%

Acoustic emission monitoring from a lab scale high shear granulator—A novel approach

Watson

Povey

Reynolds

et al. 2014

International Journal of Pharmaceutics

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A new approach to the monitoring of granulation processes using passive acoustics together with precise control over the granulation process has highlighted the importance of particle-particle and particle-bowl collisions in acoustic emission. The results have shown that repeatable acoustic results could be obtained but only when a spray nozzle water addition system was used. Acoustic emissions were recorded from a transducer attached to the bowl and an airborne transducer. It was found that the airborne transducer detected very little from the granulation and only experienced small changes throughout the process. The results from the bowl transducer showed that during granulation the frequency content of the acoustic emission shifted towards the lower frequencies. Discrete element modelling of the granulator system show that when the particles increase in size and reduce in number the number of collisions the particles experience reduces. These simulation results coupled with previous theoretical work on the frequency content of an impacting sphere explain why the frequency content of the acoustic emissions reduces during granule growth. The acoustic system used was also clearly able to identify when large over-wetted granules were present in the system, highlighting its benefit for detecting undesirable operational conditions. High-speed photography was used to study if visual changes in the granule properties could be linked with the changing acoustic emissions. The high speed photography was only possible towards the latter stages of the granulation process and it was found that larger granules produced a higher magnitude of acoustic emission across a broader frequency range.

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An investigation into the kinetics of liquid distribution and growth in high shear mixer agglomeration

Cited by 149 publications

References 19 publications

Wet granulation in laboratory scale high shear mixers: Effect of binder properties

Wet granulation in laboratory scale high shear mixers: Effect of binder properties

Predictive modelling of the granulation process using a systems-engineering approach

Acoustic emission monitoring from a lab scale high shear granulator—A novel approach

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