Olivier Lecoq

• PhD
• Professor (Assistant) at IMT Mines Albi

Dry granulation by roll compaction is a process of size enlargement used to produce granules with a good flowability for further die compaction process. To gain in the understanding of how granulated powders behave during die compaction and why they exhibit different behaviors different from those showed by the feed powder, the main material parame...

Dry granulation is an agglomeration process used to produce size-enlarged particles (granules), improving the handling properties of powders such as flowability. In this process, powders are compacted using a roll press to produce ribbons, which are milled in granules used further in the tableting process. The granule and tablet properties are infl...

Dry coating is an interesting process for creating added value binary powders composites. The principle is to mix ‘host’ particles with ‘guest’ particles with 10 to 100 times smaller size. But, behind the apparent simplicity of the process, the implied mechanisms are very complex. As a result, it is not possible so far to predict the resulting end-...

Densification process of granules from roll-compacted binary mixtures of microcrystalline cellulose, known as ductile powder, and lactose, considered a brittle material, was investigated using a full-instrumented die press. The role of each component and the effect of the granule size on tablet properties were analysed. Based on the stress transmis...

Curing is generally required to stabilize film coating from aqueous polymer dispersion. This post-coating drying step is traditionally carried out in static conditions, requiring the transfer of solid dosage forms to an oven. But, curing operation performed directly inside the coating equipment stands for an attractive industrial application. Recen...

The dissolution method is still widely used to determine curing end-points to ensure long-term stability of film coatings. Nevertheless, the process of curing has not yet been fully investigated. For the first time, joint techniques were used to elucidate the mechanisms of dynamic curing over time from ethylcellulose (Aquacoat)-based coated tablets...

This paper describes the application of a unifying ‘master curve’ model for single impact size reduction in an air jet mill. Based on a dimensional analysis and a modified fracture mechanical theory, it enables to relate the weight percentage of broken particles under sieve cut size to the mean sieve cut size of the studied material, the net kineti...

The aim of this study was to perform in-line Near Infrared (NIR) measurements inside a pan coater to monitor a coating operation in real-time, by predicting the increases in mass of coating materials and coating thickness. A polymer combination of ethylcellulose/poly(vinyl-alcohol)-poly(ethylene-glycol) graft copolymer was used as functional aqueou...

The general aim of this paper is to study the coating strength of different composite powders with an experimental approach based on mixing energy descriptors derived from linear velocity at the end of paddles. The chosen system is Cellets particles coated with Talc particles, with two size ratios: 7 and 22. The studied processes are Nara Hybridize...

In dry coating processes no liquid, solvent, binder or water, is required. This makes them advantageous compared to wet coating alternative: being low cost, no drying step required, environmentally friendly (no volatile organic compounds related problems) and simple in operation. But there is still a lack of fundamental knowledge of the implied mec...

The aim of this study is to develop a fundamental knowledge on dry coating, to understand the coating strength of different bio-couples with a theoretical and experimental approach and how the dry coating is affected by the size of host particle and choice of dry particle coating equipment. For this purpose, we examine the feasibility of dry coatin...

The average supersaturation field is predicted for precipitations in the case of partially premixed feed streams by a simple mixing model from a couple of successive experiments with the same inert tracer by Planar Laser Induced Fluorescence and using a single camera. Then, the mathematical derivation is different from that one used for the unmixed...

An experimental test rig for the study of impact in an air-jet mill (up to 500 m s−1) allows the evaluation of the relationship between the impact energy and the fineness of the impacted solids. In single impact tests, so far, three types of behaviour are found: brittle (for glass, sand, polyamide and NaCl), “complex” (for Al(OH)3) and ductile (for...

Inert liquid tracer concentrations in a continuous mixer are analyzed by planar laser induced fluorescence (PLIF). Special attention is paid to the two separated entering feed streams containing the tracer solution or pure solvent. From the instantaneous tracer concentration fields, the method proposed allows one to easily calculate the instantaneo...

The PLIF (Planar Laser Induced Fluorescence Technique) method is applied to determine experimentally the field of supersaturation in a separate double jet reactive precipitator from the local instantaneous field of concentrations of an inert tracer. The nucleation flux in the mixing region is derived.

The mixing of two water feedstreams is investigated in a 0.02m3 continuous stirred tank, from concentration measurements. These measurements are carried out with a laser sheet in a very thin vertical plane through the vessel tangent to the impeller. The proportionality between the grey level obtained by planar laser induced fluorescence and the loc...

The behaviour of a powder impacted on a target depends on its size, its particle size distribution (PSD), the material mechanical properties and the industrial rig. A methodology for the study of impact in an air jet mill allows one to evaluate the relation between the impact energy and the grindability of the impacted solids. Moreover, the behavio...

Le comportement face à l’impact d’une poudre dépend de sa taille, de sa distribution granulométrique, des propriétés mécaniques du matériau et de l’installation industrielle. Parmi la grande diversité des approches possibles pour l’étude de l’impact de matériaux pulvérulents, notre installation expérimentale de test se démarque en permettant d’obte...

The aim of this paper is to develop a fundamental knowledge on dry coating, to understand the coating strength of our bio – couples with a theoretically and experimental approach and how it is affected by the size of host particle and choose of dry particle coating equipment. For this purpose, we examine the feasibility of dry coating of two differ...