PIN MILLS

Pin Mills are the mills used for grinding variety of things. The working, advantages, disadvantages, specifications and applications of Pin Mills have been well described in the presentation.

1. PIN MILLS By:- PRATHAMESH KUDALKAR 13FET1011 MonTica Sawant 13fet1007

2. A PIN Mill

3. Size Reduction Raw materials often occur in sizes that are too large to be used and, therefore, they must be reduced in size. Size reduction of solids is termed as grinding or cutting. Grinding usually refers to reducing solids to fine particles while cutting involves reducing solids to macroscopic particles. Grinding involves reducing the size of solid materials by mechanical action, dividing them into smaller particles. It is an energy intensive process, therefore the selection of right grinder is important.

4. TYPES OF MILLS The different types of mills used in fine grinding are as follows: The Hammer Mill High Impact Turbo Mill Pin Mill The Vibrating Mill Stirred Media Mill Fluid Energy Mill Here after, we will concentrate on Pin Mills.

5. Pin Mill Pin Mills are type of Disc Grinders. Also known as Centrifugal Impact Mills (CIM) Pin mills are a type of high-speed-impact mills consisting of a feed inlet, a set of two disks with concentric rings of pins and a product outlet. Particle size of as low as 2 µm can be achieved with the use of finest quality Pin Mills. Pin mills are capable of very fine grinding without the need for screens and provide a uniform product size.

6. Principle Pin mill employs shearing and impact forces to produce fine particles The grinding action within the Pin Mill is achieved by impacting the product particles with a series of hardened steel pins. The product enters through the eye of the machine and then passes through rows of pins rotating at high speed between stationary pins. The product particles are shattered into fragments as they progress towards the outlet, progressive becoming smaller in size as they approach the periphery(this is because the distance between the pins decreases as we move radially outwards) The machine’s grinding action can be controlled by altering the feed rate to the machine and the speed of the rotor.

7. WORKING Pin Mill consists of two round disks parallel to each other. Material is fed continuously in the gap between the rotating disks. Depending on the type of the machine, one or both disks can rotate. In cases where both disks rotate, the second disk rotates in counter direction. Feeding of the product is usually done by means of a chute, shifting the product in the hole center of one of the two disks. To reduce the temperature increase, air is blasted during grinding or in construction to avoid oxidation, cooled inert gas is used ; Blast of inert gas helps prevent accumulation of particles in between the pins and on the disks

8. Working The disk has several metallic pins, placed symmetrically and concentrically on the disk surfaces.

9. Working The centrifugal force causes the particles to accelerate outward toward the disc edges and pass through the pins on the discs. The exiting particles impact a stationary outer ring (called an impact wall or liner) typically consisting of stator pins or a smooth or corrugated wall, which further reduces the particles. Sieve of the required particle size is placed on the lower part of the mill. It acts as a barrier mechanism to ensure no particle having size more than specified is found in the output. Thus, ground particles are obtained as output.

10. TYPES of Pin mills Vertical Pin Mill Configuration Horizontal Pin Mill Configuration

11. SPECIFICATIONS When one disc rotates , the size of the ground particles is 50-5 micro meter . If both the discs counter rotate , the particle size may be reduced to 2 micro meter. Pin mills may grind 0.05-6 tons/hr. Depending on the product end size of particles and capacity , the energy consumption may vary from 3 to more than 100 kW. The specific energy consumption is10-100kWh/ton at peripheral velocities 100-200m/s Usually the peripheral velocity of the pin grinder is 80-160m/s The diameter of the disc is upto 1m. The fineness of final product depends on distribution of pins, the circumferential speed of the rotors, the feed rate, and the physical properties of the material. Tips for specifying a Pin Mill Specify right number and arrangement of pins Appropriate pin arrangement (typically in rows) for your pin mill discs helps produce the final particle size distribution of choice and controls narrowness of that distribution to meet your product requirements Specify high quality parts Any internal mill surface in contact with the material during grinding is subject to wear, and in a pin mill this includes the pins, the wear plate (that is, the disc surface on which the pins are mounted), the rotor, and the impact wall at the disc periphery. These parts can also be subject to corrosion if your pin mill handles a corrosive material. Order wear parts to keep on hand

12. Advantages and Disadvantages ADVANTAGES DISADVANTAGES Very fine grinding at relatively reasonable energy consumption Little floor space required Low maintenance Gravity or pneumatic feed  Dry or wet grinding Easy cleaning ensures higher hygiene standards Noiseless operation Various internal components are available to custom-design the Pin Mill to the process Low Capacity High wear Narrow range of size reduction Internal cooling may be required(heat damages products like cocoa)

13. Applications Spices Foodstuff   Biotech & Pharma Chemical     Germ Salt Spaghetti Pill Ore Iron oxide   Curry Rice Red bean Collagen Rosin Talcum powder Clove Oats Black bean Chitosan Sulfur Washing powder Garlic MSG Green bean Medicine Shellac Chemical materials Fagara Sugar Pearl barley Agar ager Ceramic Calcium carbonate Crocus Xylitol Banana chip Monascus Dyestuff     Mustard Barley Healthy food Antibiotics Pigment       Starch Dry vegetable Yeast powder Gypsum       Wheat Glutinous rice Chinese herbs Feldspar       Soybean   Polysaccharide Pesticides    

14. REFERENCES Handbook of Food Preservation, Second Edition- Edited by Shafiur Rahman Handbook of Food Processing Equipment, Gustavo V. Barbosa-Canovas, Washington State University Unit Operations in Food Processing : By R.L.Earle & M.D.Earle Dry processing technology - A Review, Mineral Industry Research Organisation , Warren Spring Laboratory Brochures of miscellaneous Pin mill manufacturers.

15. THANK YOU!