In the pharmaceutical industry, granulation plays a key role in the production of solid dosage forms – particularly due to the pressure of rising costs. Granulation aims to form coarser ag-glomerates from fine powder. Agglomerates may consist of fixed, dry grains, and each grain is an agglomeration of powder particles of enough strength. Granules can be used directly as pharmaceuticals or can serve as an intermediate in the production of tablets or capsules.
L.B. Bohle Maschinen und Verfahren offers a wide range of granulation solutions. The company’s portfolio for manufacturing oral solids includes complete production systems as well as stand-alone machines.
High shear wet granulation is a shaping process for granulation that has been successfully used by the pharmaceutical industry for decades. With high-shear granulation, a binding fluid is added to the powdery particles in a closed tank that has an agitator blade and chopper. The agitator blade with its high-shear and compaction guarantees effective granulation. Dense granules are formed.
The chopper prevents excessive granule growth and distributes the granulation fluid throughout the product.
High-shear granulators for R&D and in production scale
L.B. Bohle´s GMA high shear granulator has been specifically designed for granulation applications in the pharmaceutical and nutraceutical industry. With many years of experience in the sector of process technology, the granulator is continuously refined, standardised and suited to the individual requirements. Furthermore, it is designed for through the wall mounting.
All GMA granulators, from laboratory to large production scale, provide the best conditions to produce high-quality pharmaceutical products by wet granulation.
A cylindrical process bowl with double dished heads is the core of the GMA and the shape of the tank in combination with the agitator blade geometry ensures an effective granulation.
The bowl connects to the head section via electrically driven lifting cylinders, which allows it to be lowered down, i.e. for inspections.
The GMA granulation system works with up to 12 bar and is pressure-surge-resistant. The pressure-surge-resistant version features extremely strong tank lifting spindles that keep the tank sealed even in the event of an accident. The head section also has a filler neck for gravity feeding. The switch cabinet is also located directly on the machine – at the rear.
Compact granulation module
The compact design of the granulation module ensures optimal results and features a high-shear mixer and fluid bed dryer side by side, complete with sieving step in between.
Not only has the width been reduced, but also the installation height is very low. For example, due to the novel lifter for the filter unit inside the BFS fluidised bed processor, an opening in the concrete ceiling for installation of equipment can be avoided. There is no need for a long pneumatic cylinder which would protrude beyond the process tower. Furthermore, the inlet plenum features a reduced overall height. Due to the flat tangential air inlet, the air flow of the distributor bottom has been optimised. The low position of the multi-function outlet valve enables easy operation during feeding and discharging. The height of the transfer tube from the BTS conical sieve to the BFS conveys wet granules in excellent ergonomic and process form. The tube is very short, straight and smooth inside. This transfer layout in combination with the multi-function valve ensures unobstructed flow without elbows or bends. A platform, which is common for traditional 2-level equipment and needs to be cleaned frequently, is not necessary with the L.B. Bohle concept.
When product flow of wet granules is required, typically it cannot be fluidised again without mechanical treatment. With the design of the tangential sieve, material blockage is virtually eliminated. The transition between the outlet of the GMA wet granulator and the BTS tangential sieve is straightforward and has no reductions. The material falls onto the unperforated bottom of the sieve via gravity. From there it is moved by the impeller through a screen vertically positioned in the cylindrical part of the sieve body. As such, the product flows tangentially in-side the tube in the same direction as the transport air, in a non-tortuous path. This allows a perfect dosage of product inside the transfer line.
Optimisation of classic wet granulation
In additional to all the technical advances, improvements in the field of safety have been made. The GMA high shear granulator and the BTS conical sieve, including the transfer tube, is shock pressure resistant up to twelve bar. Consequently, all equipment parts in contact with dust or solvents (if required) are designed for shock pressure resistance.
When it comes to how traditional wet granulation can be realised economically and ergonomically, L.B. Bohle’s Compact Granulation Module is a compelling solution. Featuring many technological advances and inherent safety considerations, the Granulation Module is an ideal multi-purpose solution that can be used for a variety of purposes.