Various Milling Technologies For Grinding Pharmaceutical Powders

In the pharmaceutical industry, fine grinding techniques are currently in use. The outcomes on the fine grinding of vitamin C, which was chosen as a model substance indicative of pharmaceutical products, were presented using different grinding mills currently in use in the pharmaceutical industry. In the pharmaceutical industry, fine grinding methods are used. The outcomes are assessed in terms of product quality, as measured by particle size and distribution, as well as operational parameters relevant to the pharmaceutical industry, such as ease of setup, ease of cleaning, and investment cost.

Product quality requirements have become increasingly stringent in recent years, especially in the pharmaceutical industry, requiring finer particles and tighter control over the mean particle size, as well as the width and cut-off of the particle size distribution. Additional specifications apply to the particle form and surface properties of powders, which are important to end-user requirements.

Types Of Mills

  • Spiral jet pancake Mill: A flat cylindrical grinding chamber is surrounded by a ring of air nozzles, each set at an angle to the chamber’s circumference. These jets form a grinding circle and a free vortex, which acts as a selector, moving unground particles outwards and sucking fine ground particles into the chamber’s middle. The product passes through a cyclone after leaving the grinding chamber to separate the coarse particles from the fine product.
  • Oval ring Mill: Grinding takes place in the lower section, and classification takes place in the upper section. Particles are fed into the mill through a Venturi feed device in the lower section, and breakage is triggered by air jets projecting particles at each other. Centrifugal force pushes the coarse particles to the outside of the chamber, where they will be processed in the grinding section. After completing the grinding chamber ring, the small particles are deposited in a filter.
  • Fluidised bed air jet mill: The air jets create a fluidized bed of particles, and grinding occurs when particles collide. These particles are then carried upwards by the air current to the turbo selector, which only allows particles of a certain size to exit the grinding chamber, which is determined by the speed of rotation.
  • Fixed hammer mill: The feed is thrown at a selector grid by the centrifugal force produced by spinning blades in the case of a fixed hammer mill. Impacts on the blades or between the particles and the grill grind the particles.
  • Pin Mill: A pin mill is made up of two discs with overlapping pins. The rotor (one of the discs) rotates at a high peripheral speed of up to 150 m/s, while the other (stationary) is stationary. A feed screw in the mill’s centre introduces the product, which exits through the periphery to a collecting filter.

The pharmaceutical industry’s grinding operations are typically limited to three or four main types of equipment, with the choice of which is normally dependent on experience and limited by the fact that more fundamental approaches have been established for the mineral industries. It’s difficult to balance the properties of organic materials with the pharmaceutical industry’s process requirements. The ability to have a certain product quality, in terms of fineness of particle size or particular surface, without inducing physical or chemical changes such as amorphisation, is the most important factor in this industry. There are other mills such as; Jet mill, ball mill, multi mill as well under the category of pharma machinery.

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