Solution for Capacity Enhancement

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Posted in: , on 9. Jun. 2003 - 15:42

Dear Sir/Madam,



Pre-grinding involves use of a suitable equipment preceding the conventional ball mill/ tube mill which carries out size reduction in more efficient way at larger particle size range. In other words, while the input material size for the ball mill/tube mill is less than 25 mm, this will become less than 3 mm after introduction of pre-grinding system. After detailed study and research combined with their own extensive experience, Nihon Cement Co. Ltd, Japan developed a superior Vertical Roller Pre-grinding Mill. Through technology transfer, ACC Machinery Company Limited, Butibori, Nagpur, a wholly owned subsidiary of The Associated Cement Companies Ltd ( ACC ) is able to offer this superior type of Vertical Roller Pre-grinding Mill ( VRPM ).

A detailed study has established the superiority of this vertical roller pre-grinding mill’s efficiency in comparison to other available technology and its suitability as a solution for both existing plants to increase grinding capacity and reduce power consumption, and for new plants seeking lower investments. Many installations are successfully working in India as well as in Japan upto the satisfaction of our customers and achieved the guaranteed performance of the equipment and the complete grinding system.

Principle of operation

Clinker is fed through a central chute in the VRPM where centrifugal force, combined with the rotation of the table, distributes product over the table surface. The table and rollers then grind the material, which is then extracted from the VRPM by gravity and a little help from a scrapper. A grinding force is transmitted to a set of three rollers through a hydraulic system.

Advantages of using a VRPM

Non-airswept grinding and is therefore energy efficient.

Considerable increase in grinding capacity as clinker grinding can be increased by more than 50% to 100%.

Power consumption of the clinker grinding system can be reduced by more than 15% to 25%.

Requires little maintenance.

Table liner and roller life can be expected to be more than 10000 hrs for table liners and more than 20000 hrs for rollers.

Salient features of the VRPM developed by Nihon Cement company Ltd, Japan

High efficiency spherical roller grinding mechanism

The spherical rollers used for the VRPM provide high grinding efficiency and more stable operation. Spherical rollers also offer high compressive force as sliding contact between table and roller is increased and the shearing force that is generated is greater. Therefore, high efficiency grinding is carried out by simultaneous compression and shear force.

Grooved spherical roller

The centrifugal force generated by the rotation of the table spreads the material across the entire table surface in a uniform layer, where it is caught between the roller and the table liner segments and crushed before being carried to the outer circumference of the table. At the same time, the rollers are set above it to produce the grinding action.

If the friction between the rollers and the clinker on the table is weakened the roller slips and vibration occurs, resulting in a fall in grinding performance. Hence, preventing roller slippage is of primary importance to the maintenance of stable operation and increased capacity and is achieved by adding grooves to the spherical rollers.

The grooved spherical rollers used in the VRPM improve performance and efficiency by trapping the clinker in the grooves and rotating in perfect synchrony with the table, thus reducing vibration and enabling stable operation.

Uniform grinding

As spherical rollers have higher periphery, a wider uniform grinding layer is formed and hence grinding efficiency is increased.

Fluctuation in quality and quantity of clinker

Fluctuations in clinker quality and feed rate can easily be accommodated.

Possible configurations

Several configurations using VRPMs are possible, such as open circuit mill, close circuit mill and pre-grinding mill feeding more than one ball mill. The VRPM can even suit customers with little installation space since the VRPM is very compact.

Interested parties may contact us on the following e-mail please:

Contact Person: Arun Chaudhry- Executive Marketing

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