This document discusses cryogenic grinding technology. It begins with introducing cryogenics and explaining the problems with conventional grinding such as heat generation and oxidation. It then describes how cryogenic grinding works by cooling materials below their embrittlement temperature using liquid nitrogen before grinding them, resulting in brittle fracture. The key components of a cryogenic grinder and its working principle are outlined. Performance data shows cryogenic grinding can achieve a final fineness of 5 micrometers using less energy. Several applications of cryogenic grinding in industries like steel machining, plastics, adhesives, and spices are provided. The merits include increased throughput and finer particles while the demerits include high operation and maintenance costs.

1. BY-
HIMANSHU TIWARI
B. TECH 3RD YEAR

2.  Introduction
 Problems faced in Conventional Grinding
 Cryogenic Grinding Technology
 Working Principle of CryoGrinder
 Performance Data &Technical Data
 Field of applications
 Superiority of cryogenic grinder over
conventional grinder
 Merits & Demerits
 Conclusion

3.  The term “CRYOGENICS” originates from Greek word which means
creation {or} production by means of cold.
 Cryogenics is the study of very low temperature {or} the production
of the same, Liquid nitrogen is the most commonly used element in
Cryogenics & is legally purchasable around the world.
 Cryogenic Grinding technology can efficiently grind most tough
materials & can also facilitate Cryogenic recycling of tough
composite materials & multi component scrap.
 The Cryogenic process also has a unique capability for recycling
difficult to separate composite materials.

4. High heat generation.
Introduction of tensile residual stress.
Less tool life.
Clogging and Gumming of the mill.
Oxidation.
Loss of Enteric oil in Spice grinding.

5. HOW..???

6. Here comes the necessity
of
CRYOGENIC
GRINDING
…..also known as Freeze
Grinding

7.  For pulverizing many materials, Cryogenic Grinding Technology
increases productivity & lower power cost.
 Many elastic {or} “soft” materials are very difficult to
pulverize(crush to fine particle),requiring long cycle times & high
power/energy consumption.
 Cryogenic grinding involves cooling a material below its
embrittlement temperature with a cryogenic fluid, typically liquid
nitrogen.
 After cooling, the material is fed into an impact mill where it is
reduced in size primarily by brittle fracture.

8.  Material is to be ground is cleaned manually & fed into
the hopper.
 From the exit of the hopper the material enters into the
vibratory feeder, which is positioned with a small
inclination towards the entry of the helical screw
conveyor, It has ability to control the fed rate.
 Liquid nitrogen from the storage container is sprayer
into the screw conveyer, The time of stay of material in
the conveyer can be maintained by varying the speed of
the drive i.e., conveyer drive.

9.  working representation of Cryo-
Grinder

10.  The sensors monitors material’s temperature in the
conveyer.
 When the mill is running, the material gets crushed
between the studs & comes out through an optional sieve
as a ground product.
 To the bottom of the mill a collecting bin is housed where
the ground product gets collected.
 The vaporized nitrogen from the mill is sucked by a
centrifugal blower & through the filter assembly is fed
back to the mill, And the cyclic process is continued.

11. fig.- Schematic representation of CryoGrinder

12. Performance Data Cryo-Mill
Field Of Application* Size reduction, Homogenation
Feed Material* Hard, Brittle, Soft, elastic & Fibrous
Feed size* Up to 8 mm
Final Fineness* Approx. 5micro-mm
Batch/Sample Volume* Max.20ml
Typical Mean Grinding Time* Pre-cooling:10 mins
grinding 1 minute
Memory for Parameter Combination* 1 nos
Technical Data Parameters
Power Consumption 160 Watts
W*H*D 385*370*570 mm
Net Weight Approx. 46 Kg
*depending on feed material & instrument configuration/setting.

13.  CryoGrinding of Steel;
The large amount of Heat is generated during
machining/grinding at high speed & feed rate raises the
temperature at the cutting zones excessively.
To overcome this problem liquid Nitrogen is fed to the
grinding spot.
 Thermoplastics & Thermo sets;
To which Nylon, PVC, Polyethylene, synthetic rubber
are commonly used in powder form, but not limited to, a
variety of applications such as adhesives, powdered
coatings, fillers & plastic sintering & molding.

14. Adhesives & waxes;
To avoid pliable & sticky of certain materials
which is unable in conventional grinding.
Explosives;
To grind the explosive materials(TNT) below
their Ignition Temperature.
Spices;
To overcome the volatility of Etheric Oils (gives
the taste & smell of spices).

17.  MERITS:
1 .Increased throughput & power saving.
2 .Finer particle size.
3 .More uniform particle distribution.
4 .Lower grinding cost.
5 .No heat generation.
6 .Prevent oxidation.
.

18. 1 .High operation cost.
2 .Maintenance cost is above the
range.
3 .Filtering of Screw Conveyer is
Difficult.
4 .High power consumption.