Working and principle of Rapid Mixer Granulator (RMG)

Rapid Mixer Granulator is a multi-purpose processer equally suitable for high speed dispersion of dry powders, aqueous or solvent granulation, and effervescent products and melt pelletization.
Wet granulation is a common step in the manufacture of many solid dosage pharmaceuticals. Wet granulation can be accomplished in a mixer granulator. A mechanical impeller moves the powder while a liquid binder is applied onto a moving powder bed. Addition of the liquid binder starts the formation of granules. The granulator also has a chopper.
Impeller and chopper are mainly responsible for wet granulation in the rapid mixer granulator.
Rapid Mixer Granulator is designed to achieve excellent mixing and consistent granules at lower operating cost along with higher productivity. Better mixing and closed control of granule size leads to faster tableting speeds with improved quality and least rejections.
The granulation is conventionally performed in the following process steps:
Mixing of dry material at high impeller and chopper speeds for a few minutes.
Addition of liquid binder by pouring it on to the powder, while both the impeller and chopper are running at a low speed.
Wet massing with both agitators running at high speed.
Impellers: Impellers are fixed at the bottom of dome shaped stainless steel bowl. It has fully length and two half-length blades. Impellers are designed such a way that small blade lift the material and full length blades push the material to mix well. These impellers break up the wet mass into small pieces and granules.
Chopper: These are specially designed small blades located at the bottom of the dome. The primary function of chopper is to cuts the lumps into smaller fragments those are mixed equally by impeller and aids the bowl or sprayed onto the powder to achieve a more homogeneous liquid distribution. It rotates at high speed (1440/2880) RPM to give easy and uniform granulation. The speed of chopper is responsible for the size of granule. Chopper does not have any significant effect on the granule size when impeller speed is high (above 200 RPM).
Discharge Port: The discharge port is mounted horizontally into the dome with vertical downward opening. Granules are unloaded in the container through the discharge port. Opening of discharge port is operated by pneumatic cylinder (compressed air cylinder) that requires 3-5 kg/cm2 pressure of compress air.
Working Principle: The Rapid Mixer Granulator is mixing unit with a bottom entry agitator ad side mounted chopper for granulation. It is used for dry blending, wet mixing, preparation of dough and granulation, i.e. cutting of the wet mass into small size granules. It works on the basic principle of agitation of the contents of the bowl at moderate speed and then running a specially profiled cutter blade at high speeds into the wet mass.
Dry mixing takes about 3-5 minutes to mix the ingredients, wet mixing takes 5-10 minutes to make the wet mass of material while the granulation process takes 5-10 minute to 0.5 mm to 1.5 mm sized granules.
Mixing time consumed in processing is depends upon the ingredients quantity and their particle size.