Granulation, the process of particle enlargement by agglomeration technique, is one of the most significant unit operations in the production of pharmaceutical dosage forms, mostly tablets and capsules. Granulation process transforms fine powders into free-flowing, dustfree granules that are easy to compress. Nevertheless, granulation poses numerous challenges due to high quality requirement of the formed granules in terms of content uniformity and physicochemical properties such as granule size, bulk density, porosity, hardness, moisture, compressibility, etc. together with physical and chemical stability of the drug. Granulation process can be divided into two types: wet granulation that utilize a liquid in the process and dry granulation that requires no liquid. The type of process selection requires thorough knowledge of physicochemical properties of the drug, excipients, required flow and release properties, to name a few. Among currently available technologies, spray drying, roller compaction, high shear mixing, and fluid bed granulation are worth of note. Like any other scientific field, pharmaceutical granulation technology also continues to change, and arrival of novel and innovative technologies are inevitable. This review focuses on the recent progress in the granulation techniques and technologies such as pneumatic dry granulation, reverse wet granulation, steam granulation, moisture-activated dry granulation, thermal adhesion granulation, freeze granulation, and foamed binder or foam granulation. This review gives an overview of these with a short description about each development along with its significance and limitations.
Recently, enormous efforts have been done within the development of Li-ion batteries for use in portable electric devices from small scale applications such as mobile phones, digital cameras, laptop computers, to large scale applications like electrical vehicles (EVs) and hybrid electric vehicles (HEVs). LiFePO4 as an active material in cathode materials in Li-ion batteries has shown outstanding advantages compare to other cathode materials such as low cost, low toxicity and environmental compatibility, good thermal stability, high theoretical specific capacity of 170 mAh/g and operating reversibility at 3.4V. Still, it is a need to develop the manufacture of the cathode material to achieve improved performance reliability by using environmental sustainable processes in order to meet future demands in large scale production and uses of Li-ion batteries.
The aim of this work was to develop a non-toxic, cheap, efficient and environmentally friendly process for synthesis of high quality active cathode material based on LiFePO4 for Li-ion batteries. Water based suspensions/solutions containing various reactant constituents have been homogenized, granulated and calcined. Freeze granulation was applied as the key tool for the synthesis of LiFePO4 with integrated carbon in order to produce granules with high degree of homogeneity prior to calcination. The resulting powder materials have been evaluated by XRD, carbon and conductivity measurements and characterization of other physical properties such as density and specific surface area. The promising version was used for manufacture of cathode material by tape casting, cell assembling and evaluation of the performance by charge/discharge cycling of the cells.
For the best sample in our experiment the XRD results revealed a high degree of purity, homogeneity and crystallinity of LiFePO4. The produced LiFePO4/C composite also had a high specific surface area and, therefore, considered as a promising material for cathode manufacturing and cell assembly. A discharge capacity of 155 and 140 mAh/g was achieved at the fifth cycle at 0.1C rate at room temperature for the cathodes which were made with NMP (solvent based) and water system, respectively. The long-term stability test indicated good result with no loss in capacity for at least 390 cycles. The satisfactory discharge capacity should be attributed to the homogenous nano-sized particles with a conductive porous carbon structure that was provided by the freeze granulation process and adapted calcination process.
Keywords: Li-ion batteries, LiFePO4, cathode active material, specific capacity, freeze
granulation, calcination, LiFePO4/C composite, cell assembly.
In the present study the freeze granulation technique is applied in the manufacturing process of Mn-Zn power ferrites.The powders are prepared by the solid state reaction method and a comparison between the standard industrially used spray-drying method and the freeze granulation process with subsequent freeze drying has been carried out, in terms of granulate morphology, compaction behavior and pore size distribution, sintering behavior and magnetic performance. It apeared that the freeze granulation process enables the formation of homogeneous green compact microstructures and finally leads to sintered products of good magnetic quality. Consequently, Mn-Zn ferrites with low losses of 287 mW/cm3 (at measuring conditions f=100 kHz, B=200 mT and T=1000C) are manufactured.
Granulation is one of the most important unit operations in the production of pharmaceutical oral dosage forms. Granulation
process will improve flow and compression characteristics, reduce segregation, improve content uniformity, and eliminate excessive amounts of fine particles. The results will be improved yields, reduced tablet defects, increased productivity, and reduced down time. Pharmaceutical products are processed all over the world using the direct-compressing, wet-granulation, or dry granulation methods. Which method is chosen depends on the ingredients individual characteristics and ability to properly flow, compresses, eject, and disintegrate. Choosing a method requires thorough investigation of each ingredient in the formula, the combination of ingredients, and how they work with each other. Then the proper granulation process can be applied. The objective of present article was to focus on the novel granulation technology.
ECerS XIII Conference – Limoges, France – Welcome to PowderPro’s stand No 1 at the exhibition at ECerS XIII Conference (European Ceramic Society) in Limoges, France from the 23rd to the 27th of June 2013. We look forward to meet customers, partners and new contacts for interesting discussions in our stand!
We plan to have our equipment available at a nearby lab for you to see the process of Freeze Granulation.
Freeze granulation, as opposed to spray drying, has been shown to produce protein particles with light and porous characteristics, which offered powders with superior aerosol performance due to favorable aerodynamic properties, suitable granulation technology for protein inhalation powders.
If you don’t find the information you need, please contact us. We’re always glad to help.
Spray-freezing and freeze drying – Freeze Granulation
PowderPro AB develop, manufacture, market and sell equipment and know-how for Freeze Granulation, spray freezing and subsequent freeze drying (lyophilization or cryodesiccation). Freeze Granulation was developed in late 1980s at Swedish Ceramic Institute in Göteborg and it is also a development of Spray Freeze Drying (SFD) and Spray Freezing into Liquid (SFL).
Spray cooling or rather called spray freezing is the first step in the freeze granulation process where a suspension is atomized, sprayed with a nozzle, into a chamber with liquid nitrogen. The small droplets are then rapidly frozen with a minimum of ice crystal growth. The frozen material (granules) are then transferred to a freeze dryer where the ice is removed by sublimation, i e never go through a liquid state that ensure homogeneity preservation.
Below you can see an illustration of the Freeze Granulation process.
POWTECH 2013 – Nürnberg. Good and interesting meetings on powder processing and how Freeze Granulation can improve the homogeneity of the granules, for example nanomaterial like CNT – Carbon Nano Tubes.
Freeze Granulation produce flowable and crushable (soft) granules suitable for die pressing applications. Spray drying yield flowable, but hard granules which are difficult to cruch during die pressing.