A novel methodology to study polymodal particle size distributions produced during continuous wet granulation

Abstract

It is important during powder granulation to obtain particles of a homogeneous size especially in critical situations such as pharmaceutical manufacture. To date, homogeneity of particle size distribution has been defined by the use of the d combined with the span of the particle size distribution, which has been found ineffective for polymodal particle size distributions. This work focuses on demonstrating the limitations of the span parameter to quantify homogeneity and proposes a novel improved metric based on the transformation of a typical particle size distribution curve into a homogeneity factor which can vary from 0 to 100%. The potential of this method as a characterisation tool has been demonstrated through its application to the production of granules using two different materials. The workspace of an 11mm twin screw granulator was defined for two common excipients (α-lactose monohydrate and microcrystalline cellulose). Homogeneity of the obtained granules varied dramatically from 0 to 95% in the same workspace, allowing identification of critical process parameters (e.g. feed rate, liquid/solid ratio, torque velocities). In addition it defined the operational conditions required to produce the most homogeneous product within the range 5μm-2.2mm from both materials.

Continuous twin screw granulation and fluid bed drying: A mechanistic scaling approach focusing optimal tablet properties

“…In detail this general effect resulted in a decrease of particle fine fraction for both formulations at increasing ML and an increase of the coarse particle fraction for F2, too. That observation is in very good agreement with results in literature, where the impact of L/S-ratio (directly connected to granulation ML) on granules particle size was also investigated [14,16,49,53,54,61,64,69,70,71,88,89,90,123,129]. All that papers showed the effect of decreasing particle sizes at increasing granulation ML for very different formulations and process parameter settings.…”

“…Based on formulation-dependent differences and differences on how PFR and/or FL were varied during the experimental setup, different effects of PFR and FL on granule PSD became visible. Increasing particle sizes at increasing PFR and FL simultaneously were found by several researchers [68,69,70,129]. The effect of increasing In terms of tableting behaviour, surprisingly the formulation including cellulose showed no impact of FL and PFR (only a slight increase of tabletability with increasing PFR).…”

“…Adaption of barrel fill level FL by decreasing of screw speed at a specified PFR lead to a decrease of fine fraction for both formulations and a decrease of coarse fraction for F1 and in contrast to that, to an increase of particle coarse fraction for F2 at low PFR. The impact of PFR, screw speed and barrel fill level FL on granule material attributes was investigated by several research papers [14,21,30,34,49,50,53,68,69,70,107,129]. Based on formulation-dependent differences and differences on how PFR and/or FL were varied during the experimental setup, different effects of PFR and FL on granule PSD became visible.…”

Covellite (CuS) Production from a Real Acid Mine Drainage Treated with Biogenic H2S

“…Table 4 shows the particles diameter distribution (Dv(10), Dv(50), and Dv(90)) of the samples. Dv index characterizes the particle size distributions, which are calculated through intercepts to 10, 50, and 90% of the cumulative volume [21]. In general, the higher exposure time of AMD to biogenic H2S (CuS96) resulted in smaller covellite particles as observed by Dv(90) and Dv(50) distribution parameter (Figure 4).…”

A particle size distribution measurements of selected building materials using laser diffraction method

“…1) for the analysis of optical images consists of: a monochrome light source (laser beam); an optical system forming its beam; an optical image that was made of suspended powder grains in liquid which enables the passage of light and causes its diffraction on the edge of the grains; an optical system transforming the beam of transmitted light; an image detector that was created by the beam of light; a converter; a computer recording all data. Diffraction methods are used for the granulometric assessment of grains in many branches of industry such as the construction, food and pharmaceutical industries [3,9,11,12,18,25,30,[32][33][34].…”