How can you make powders of particle size invisible to human eye?
The resolving power of a human eye is 100 microns (0.1mm). Any particle less than 100 microns cannot be distinguishingly identified by a normal eye – that’s one reason why we cannot see the Red blood cells (RBC) in our blood (5 microns (0.005 mm))!
Conventional grinding methods like Air Classifying Mills & Hammer Mills can help you achieve fineness levels up to 10 microns which generally comes as a limitation for ultrafine powder requirements of less than 5 microns, like Pharma APIs. This is where Jet mills, with their fineness levels of 1-2 microns, come in.
Unlike conventional grinding mills that use impact forces to grind material, Jet mills use high pressure air media. High velocity air is passed through the nozzle into the grinding chamber where the kinetic energy of the high pressure and high velocity air stream causes the material to micronize in the grinding chamber.
The nozzles are positioned in a manner that produces centrifugal action on the particles. The lighter particles are pushed towards the centre of the grinding chamber and the heavier particles towards the periphery. Lighter particles of desired fineness are then evacuated from the centre of the chamber through a static classifier.
| Spiro Model (Mill Dia in inches) | Capacity (kg/hr) |
|---|---|
| Spiro- 4 | 0.3-10 |
| Spiro- 8 | 5.0 - 40.0 |
| Spiro- 12 | 20-100 |
| Spiro- 16 | 60-150 |
| Spiro- 20 | 0.3-1090-200 |
| Spiro- 24 | 120-350 |
| Spiro- 30 | 180-500 |
| Spiro- 36 | 350-700/td> |
There is huge increase in surface area of the jet milled product compared to other grinding technology. When reduced to 5 microns, a 30-mesh product has 1,600,000 times more particles and the surface area is more than 100 times greater. Here are some of the ultra-fine powder applications where a Jet Mill serves as a perfect choice.
The following table shows the comparison of a Spiro Jet Mill compared to other grinding methods like Hammer Mills, ACMs –
| Parameters | Spiro Jet Mill | Ball Mill | Hammer Mills | Air Classifying Mills |
|---|---|---|---|---|
| Material contamination due to mill component wear out | Low | High | Moderate | Moderate |
| Liner material | During high abrasive applications | >5 types based on application | >5 types based on application | >5 types based on application |
| Compressed Air | Yes | No | No | No |
| Fineness | Up to 1 micron | Less than 1 micron | 500 microns | Up to 10 microns |
| Capacity in Horse Power | 1 to 100 | 10 to 1000 | 10 to 250 | 3 to 600 |
| Number of components | Less | More | More | More |
| Moving Parts | No | Yes | Yes | Yes |
High pressure compressed air is the major source of power consumption in a Jet Mill. The compressed air required by jet mill is directly dependent on the number of nozzles. Typically, on an average, each compressor horsepower delivers around 4 SCFM of air.
Other than a source of generating fluid energy (typically a Compressor) a jet mill configuration includes:
- A feed system to meter the material to the jet mill at a constant rate – Screw, Vibratory, or Loss-in-Weight feeder
- A separation system to separate ground powder from the air stream – Generally Filter bags/ Cyclone collectors/ ESP
- Other add-ons – Remote control system, aspiration air filtration systems, etc.
With an experience of 46+ years, RIECO’s Grinding Systems have catered to the fine powder grinding requirements of 3000+ happy customers across the globe in their Food, Spices, Pharma, and many more requirements.
Connect with our experts @Johnson Rego and @Shahrukh Khan to learn about Spiro Jet Mill and visit www.rieco.com to know more.