Roll compaction

P,n and the roll compaction time control compact density. Generally speaking, as compaction time decreases (e.g., by increasing roll speed), the minimum necessary pressure for quahty compacts increases. There may be an upper limit of pressure as well for friable materials or elastic materials prone to delamination. 

Roll compacting and briquetting is done with rolls ranging from 130 mm dia by 50 mm wide to 910 mm dia by 550 mm wide. Extrudates are made 1-10 mm thick and are broken down to size for any needed processing such as feed to tabletting machines or to dryers. 

The equipment feed design consisted of a funnel-shaped powder hopper (with no vacuum deaeration system) that was located directly above the rolls. The powder hopper was retrofitted with vacuum deaeration capability. A high compression feed screw, fitted inside the funnel hopper, fed the powder directly into knurled rolls. The compaction trials were conducted with and without vacuum deaeration. The compact was carefully collected directly on a 10-mesh screen. Powder particles, that were not compacted (i.e., those particles which were not attached to the compact, for example, fines bypassing roll compaction and the non-adhering compacted powder particles) were weighed and separated. The compact was not milled. The parameters are noted in Table 4. 

Results of roll compaction and milling trials indicated that there were insignificant differences between pilot and plant scaling. All laboratory and... 

Sheskey P, Sackett G, Maher L, Lentz K, Tolle S, Polli J. Roll Compaction Granulation of a Controlled-Release Matrix Tablet Formulation Containing HPMC, Pharmaceutical Technology Tableting and Granulation Year book. Advanstar Communications, Pittsfield Mass. 1999 6-21. 

Sheskey P, Pacholke K, Sackett G, Maher L, Polli J. Roll compaction granulation of a controlled-release matrix tablet formulation containing HPMC. Pharm Technol 2000 24(ll) 30-52. 

Figure 12.10. Equipment for compacting, briquetting, and pelleting, (a) Flowsketch of a process for compacting fine powders, then granulating the mass (Allis-Chahners Co.), (b) Integrated equipment for roll compacting and granulating (Fitzpatrick Co.), (c) A type of briquetting rolls, (d) A gear pelleter. (e) A double roll extruder.

Preparing granulation solution 4. Wet massing 5. Wet screening 6. Drying 3. Roll compaction ... 

Roll pressing Powders compacted by squeezing between two rolls. Powder rolling, roll compaction Roll presses... 

Roll pressing 1. Particulate material, with or without binder, is compacted by squeezing as it is carried into the gap between two rolls rotating at equal speed Briquetting, roll compacting Compacting rolls with smooth, corrugated or pocketed surfaces... 

In the pharmaceutical industry large, often poorly-formed, tablets or slugs are made from fine cohesive powders in large capacity tablet presses and then comminuted to form a granular feed suitable for final tableting [10]. Slugs are typically 1 or 2 in. (2.5 or 5.1 cm) in diameter and perhaps in. (1.3 cm) thick. Results comparable to those accomplished with this piston and die method are also obtained by roll compaction followed by granulation (see Section 2.2). 

Fig. 5.2. Schematic diagram of a roll compaction and briquetting press [13].

Compaction Granulation. This process involves the use of mechanical force to form granules (dense particles) from finely divided solid materials.7 In this process (Fig. 24.18) the fine materials are weighed and, depending on the desired grade, thoroughly mixed. The mixture is then continuously fed to a pressure-roll compaction machine that forms the powdered mixture into a dense, hard sheet of material usually about 2-3 cm thick and... 

Sheskey, P. J., and Hendren, J. (1999),The effects of roll compaction equipment variables, granulation technique, and HPMC polymer level on a controhed-release matrix model drug formulation, Pharm. Technol., 23, 90, 92, 94, 96, 98,100,102,104,106. 

Compactor design features have evolved over the years. By the mid-1970s, research revealed a number of roll design improvements that increased compacting efficiency. Three key conditions were identified, at that time, which optimized the roll compact throughput and minimized leakage of non-compacted powder. ... 

Miller noted that the total compaction power requirement is the sum of the power required for the feed screw(s) and the roll drive. Feed screws not only convey the powder material from the compactor storage hopper but they also help deaerate the powder in the process. The deaeration of the powder acts as a mini compactor by precompacting the material just prior to roll compaction. Optimum compaction pressures and feed screw designs vary widely for different powder material properties. Changes in bulk powder density and feed screw speeds will affect the roll gap, the compaction pressure, the throughput, and the quality of the compact. ... 

Traditionally, tablets have been made by granulation, a process that imparts two primary requisites to formulations compactibility and fluidity. Both wet granulation and dry granulation (slugging or roll compaction) are used (Table 1). Regardless of whether tablets are made by direct compression or granulation. 

Freitag F, Kleinebudde P. How do roll compaction / dry granulation affect the tabletting behaviour of inorganic materials Comparison of four magnesium carbonates. Eur Pharm Set 2003 19 281-289. 

Roll Compacting and Briquetting 354 Tabletting 357 Extrusion Processes 358 Prilling 361... 

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