Hello Jon,

There are two methods to minimize dust emission in surrounding environment.

1) Dust extraction system :

As an example, this is like domestic vacuum cleaners wherein air is extracted at dust generation area, dust separated and clean air is discharged in to atmosphere. Example is only for simple explanation, however, dust extraction systems are of much larger size, in specialized form and designed for continuous operation round the clock.

2) Dust suppression system :

The dust suppression system applies fine spray of water or water mixed with chemicals. The spray wets the particles and the particles settle down due to heavier weight. Dust suppression is often preferred however, its limitations are:

- Addition of water / moisture, may be objectionable for certain material

- One avoids to add water / moisture before crushing / before screening, because it may interfere with the crushing / screening operation.

The dust suppression is also used to prevent dust being carried by air from stock-pile surfaces. In this, water is sprayed on stock pile surface at regular time intervals, automatically.

Both the above systems have been extensively used in India in many coal-based power stations (around 150 power stations).

There are manufacturers of both these systems in UK. You can contact them and seek their suggestions / recommendations / literature.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyor.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 5882916 ■

A 3rd Method of Dust Emission Control:

PREVENTION: don't generate the dust and you don't have to extract or suppress it. Properly designed chute transfers, using engineering physics of solids granular flow and gas dynamics turbulence, will minimize dust emission levels and overall maintenance. Chute designs can be compared and differences quantified which exhibit lowest gas velocities to warranty dust leves by particle size.

Why spend unnecessary monies on collection and suppression?

Lawrence Nordell

Conveyor Dynamics, Inc.

website & contacts: www.conveyor-dynamics.com ■

Dear Sir.

We have similar problems in our Sea Port Terminal, we have to unload 100.000 ton of coal a year and we have the port terminal prepared with ship unloader, conveyors, silos, and Spouts for so many products differents to coal then we are doing engineering to solve the problem. Mainly with dust emission because the enviro regulations are very strict in Chile.

Some of the ways are well related in the forum for one of the peoples from India, the moisture of water is one way if your client can accept 2% plus of water in the product.

If you have closed your conveyors the sistem works very well.

Regards

Marcelo Alonso.

Santiago - Chile ■

To find more information on Benetech in general, you may consult the website www.benetechusa.com.

Benetech GmbH in Germany has extensive experience with dust management for hard and brown coal conveyed. Among others, Benetech GmbH has been a partner of MIBRAG, the largest brown coal producer of Germany for many years now, providing dust suppression for their brown coal mine.

The Benetech Engineering departments will be pleased to help you in finding a solution for your dust problem.

Best regards,

Benetech GmbH

Karl Liebknecht Str. 27

D-06682 Deuben near Leipzig

Germany

Email: benetech@gmx.de

Tel: +49-34441-445-0

Fax: +49-34441-445-20 ■

Given the number of replies, it is evident that the remedy to your dust control problem will depend on its cause - which you have not identified. Since you happen to be in a country with many resources available to you, you can get help relatively easily.

I suggest that you contact belt/conveyor service companies, such as Vulcanisers International in Lancashire. Alternatively, companies such as Benetech or Rema can offer assistance.

Good luck with your project. ■

We and others have been quite successful in designing transfer chutes that do not generate dust particularly in coal transfer operations. There are many reference sites. The key is in the material flow control such that there is minimum aeration of the material during the transfer process plus minimal impact of the materail within the chute. What airflow that is induced is controlled and "stilled". The techniques and designs used are proprietary and therefore to use these techniques you re going to have to pay for the designs. In this respect we can help.

There are alternatives as others have suggested that are more freely available but I would suggest that conventional baghouses are the least desirable as they are expensive and definitely not as effective as the passive systems we use.

All the best

Col Benjamin ■

DEAR Marcelo Alonso.

Santiago - Chile,

PLEASE NOTE THAT SINCE I DO NOT KNOW THE SHAPE OF UNLOADING HOPPER OF THE SHIP UNLOADER BUT A SPECIAL TYPE OF UNLOADING HOPPER WITH DOUBLE WALLS CAN ALSO REDUCE THE DUST EMISSION AT UNLOADING POINT.

ANIL

INDIA ■