Dear Ranga, Your question in incomplete,you need to tell us the following--

1.Type of material you are stockpiling.

2.System of stockpiling,if you will drop the material from height with a fix chute then the dust generation shall be more and if you will drop the material with a retractable chute then the dust generation will be very less.

Anil Seth

www.libranengineering.com

0981105560 ■

Dear Ranga, Invest some money by converting your fixed chute in to retractable chute . I think this will be better option .

Anil ■

Dear Shri Ranga,

It seems you are the user of radial stacker. If so, you can invite the quotation from the regular supplier of the dust suppression equipment and they will recommend the pump size, water quantity etc. required for your application.

The calculation for spraying and its quantity is a specialised subject and the regular designer and supplier would be the best people to decide about the same. In general, dust suppression system employing water does not add moisture more than 1 to 2% of the material.

You have referred dust suppression at the discharge point of the stacker, i.e. dust suppression to minimise emission of dust from the material falling to the ground. But there is also another issue for dust suppression relating to the stockpile already formed. The wind will carry away the material dust from the surface of the stock pile. Prevention of this loss or environmental pollution is also part of the dust control necessity. This can be prevented by use of automatic sprinklers spraying the specific quantity of water on the stockpile surface in a preplanned automatic mode. Its can be made to use depending on the season and climatic condition.

Regards,

Ishwar G Mulani.

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

Author of Book : Belt Feeder Design and Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25882916 ■

While appreciating the input furnished by Shri Rajesh Mendirata, I would like to add following information with respect to my reply for more clarity to the readers at large.

I have mentioned likely addition of water due to dust suppression spraying. This is in addition to moisture / water already present within material.

The water quantity to be sprayed will vary depending upon the season and geographic location. For example, if we are referring to the water spraying on stockpile faces to prevent dust emission, its mode of operation is likely to be as below.

- There are water sprinklers spaced at certain pitch along the edges of the stockpile.

- The sprinkler sprays the water one by one at a selected time interval, in a successive manner.

- If the system is operated properly, the operating engineers would decide the duration of water spraying according to the season. For example in a wet or rainy season they will have a shorter duration of spray and longer duration of idle time, or no spray. However, during dry or hot season they can have a more frequent spraying as per the field observation. There is no great complexity in this matter, it is like spraying water on the garden plants, which we judge and spray according to the need and season.

- When we say it adds so much of percentage of moisture in material, it has also bearing on the mode of reclamation. The idea of the sprinkler spraying is to keep only the surface moist so that there is no dust pollution due to wind. Now, this wet layer / crust of the surface material will get mixed up with the specific depth of the material being reclaimed. For example when it is reclaimed by the bridge type stacker reclaimer machine, surface crust which is containing more moisture gets thoroughly mixed up with the entire cross section of the material and thereby effective addition of moisture in material being reclaimed at a time, would be quite small as a percentage.

- Same thing also happens with linear stockpile of say 10 m height and reclaimed by bucket wheel reclaimer in say three benches. In this case the wet surface layer will get mixed up with the material of 3.3 m depth and so, reclaimed material will have a very small percentage of moisture.

- As the people already know, water is sprayed at transfer points is monitored by the quantity of material on belt and the belt speed. Such monitoring possibly does not maintain exact proportion but it maintains the workable proportion within the set parameters.

Regards,

Ishwar G Mulani.

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

Author of Book : Belt Feeder Design and Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25871916 ■

DSH Systems have an award winning dust suppression hopper that contains the dust while bulk loading dry granular products. The product falls in a solid moving column, containing the dust and is suitable for loading into storage heaps, railcars, trucks etc.

If you would like to talk to us about your dust problem to see if we can offer assistance, please advise loading rates, specific bulk density and particle size of the Pet-Coke. ■