Re: A Fine Way To Superfines
Dear Mr. Akkerman,
When you offer comparisons of comminution efficiency could you provide the work index as a function of surface area generated ie:
Comminution Efficiency Index =( kWh/Ton) / Surface Area Liberated
This takes much of the guesswork out of comparing comminution performance trends except for wear, no. of operating machines, manpower and maintenance. ■
A Fine Way To Super Fines
Dear Mr. Nordell,
You are right!
Herby are the energy consumption figures
for grinding quartz sand:
Milled material is under five microns and 30% of this material is under one micron in size.
Surface area by BET 5.1m2/gr (in the filter)
3.2m2/gr (in cyclone)
(continuous action)!
Feed fraction 5mm!! (F80 2000 microns) -- Which means unmatched reduction ratio.
Energy consumption for quartz sand for d97 is:
5 microns max. 163 kWh/t
10 microns max. 103 kWh/t
20 microns max. 71 kWh/t
30 microns max. 58 kWh/t
40 microns max. 43 kWh/t
50 microns max. 40 kWh/t
60 microns max. 35 kWh/t
70 microns max. 28 kWh/t
Hereby is further information on our mill especially with respect to wear rates, mechanical reliability and scale up to commercial sized units.
1. Gear life span – a by product of our technology is a high speed, high efficiency planetary (epicyclic) gear with planned life span.
So we can plan life span of the gear for 10,000 or 20,000 hours.
Liner wear would be 0.1 kg/ton milled product (quartz sand).
Grinded media powder fraction 0.1% (for milled quartz sand)
Liners & Grates should be changed once a week.
Liner & grates material is plain cheap steel, so better wear results with more durable materials is evident.
Grinding media material is bearing’s balls.
As a principle the wear rates of liner and grates will be similar to wear rates in a ball mill.
Right now the mill is running at a constant 30 g acceleration factor, which for several applications would be too much,
so we are modifying with frequency converter to lower g factor- of course the wear rates then will be lower.
Concerning maintenance:
One person can disassemble completely & assemble the mill within six hours. (liners & grates change would require less time)
Except the gear everything else in the mill is gorilla proof.
The gear needs an experienced mechanic.
But I assure you our gear design is far from being complex as in Hicom- Mill for example.
2. Scale up possibilities – up to 25 ton/h capacity with grinding media milling and 50 ton/hour at AG grinding.
Our math model and the model of grinding media movement optimization go only this far for today.
The larger the mill would be, the bigger the feed fraction it could intake up to 50-70 millimeters!
3. Compact size – our PCM has four drums, five liter volume each! with 1.5 ton/h milling capacity
A mill with 20 times higher capacity, will be only 5-6 times bigger.
Grinding media charge 38%.
No vibration—no need for foundation
my regards
to Dr. Herbst ■
A Fine way to Superfines
A fine way to super fines.
New technology has been developed in an effort to improve the production process of superfine powders.
Currently, there are only a few large scale methods used.
Disintegration in a ball mill through increased circulation (depending on the hardness of the material) and increased duration of the grinding.
Energy consumption grows up to 500 kW/ton. The minimum size of product 20-50 microns.
Disintegration in vibrating mill. The mills are simple in operation ,yet demand frequent service with a insufficient size reduction efficiency, although relatively low power draw but limited up scale capabilities.
Air pressure (Jet) mills. Energy consumption is 1,500- 8,000 kWh/ton, depending on the initial fraction, and hardness of the milled material.
There are various electromagnetic, ultra sonic, pulsed and other methods of superfine disintegration but they are hardly adoptable to industrial scale production.
A search for a high efficiency method for superfine disintegration resulted in developing the planetary centrifugal mill (PCM). This mill is based on the same principles as the ball mill.
However besides rotation about its own longitudinal axis, the drum is imparted a motion about an axis of the motion of transport (as planets rotate about the sun).
The motion of transport “replaces” the gravity acceleration acting on the balls in the ball mill.
With centripetal acceleration of the motion of transport acting upon the balls in a PCM, gravity acceleration is increased tens and hundreds of times (10-300 g).
This says Ezry Akkerman marketing director for the products developer, Cyclotec, is the most cost effective large scale production method for ultra fine and sub micron powders.
This technology he says, will play a key role in the development and production of innovative materials.
PCM (planetary centrifugal mill) properties:
1. Compact size.
2. Significant energy saving.
3. Extended run time.
4. Ability to operate under superior centrifugal loads (30-100 g acceleration factor) - no critical speed
limitation.
5. Simplicity of continuous feed and discharge of the raw & grinded materials.
6. Simplicity of removal of the excessive heat and dust.
7. No vibration – no need for foundation
8. Simplicity of the design – we practically have four ball mills united together- meaning simple production
adaptation.
PCM mechanical design is not so complex as existing nutational mills while having good grinding results.
9. Maintenance – easy & simple – complete disassembly & assembly takes six hours by one person.
10. Grinding Media charge ---- effortless and could be done without stopping the grinding process.
11. Autogenious Grinding – great potential for the realization of the technology of AG with various
materials --- energy savings, eliminating contamination.
12. Our mill could perform in either dry or wet grinding process
Ezry Akkerman
Marketing Director
Cyclotec Oy
cyclotec@gmail.com
www.cyclotec.net ■