Two of the common problems that I have seen are bags falling from the tube sheet to the bottom of the bins, and lack of understanding on how to ground the bag assembly. Bags fall because the diameter of holes in the tube sheet is very close to the diameter of the lip of the bag. I have not seen any vendor who makes bags with sewn grounding wires.

You may like to consider changes in the design of your dust collectors to make these two improvements.

Regards,

Amrit Agarwal (Tim)

Pneumatic Conveying Consultants

polypcc@aol.com ■

i have some interesting new systems..........applying to the aggregate industry......which is constantly fighting the suppression of dust........to calm down their neighbours who are constantly complaining.

These systems to NOT use copius amounts of free water to suppress airborne dust........but, use compressed air to FOG the airborne dust and eliminate the condition.........and NOT create other problems with free spray water and dust........intermingling on the ground and causing havoc. ■

Mr. Davies and JohnP

There is a new science of dust control. Some have labeled the science "passive dust contol". The principle is based on the concept of dropping the gas velocity below the particles terminal velocity in which the particle will fall against the pull of gravity.

The ore charge flows and displaces gas in and about itself. The disturbed gas field, can under many circumstances, be controlled. Boundary surfaces can direct both the ore flow direction and gas dynamics. Gas dynamics is now being controlled by strategic placement of baffles or curtains sometimes called "stilling chambers". These chambers act in a manner similar to the silencer of a gun. Provide expansion chambers, in critical locations and sizes, to absorb the gas dynamic pressure and velocity gradients. As the gas enters these chambers, its velocity is significantly reduced allowing the fugitive dust to decant.

Different treatment is used in the design of continuous flow verse intermitent flow.

Give us a call and visit our website to explore the potential.

Lawrence Nordell

President

Conveyor Dynamics, Inc.

1111 West Holly St.

Bellingham, WA 98225

USA

ph 360-671-2200

fx 360-671-8450

website: www.conveyor-dynamics.com ■

Dear Mr. Davies and all interested parties,

The basics of dust control lies in being able to control and predic material flow as to prevent the dust from being generated in the first place. We have an extensive back ground in material handling and discrete element menthods (DEM) technology and have applied it to a wide range of industries and many coal handling power plants in transfer point designs as to limit the dust and eliminate as much of the dust as possible if you would like to know more please visit our web page at:

www.overlandconveyor.com

or our webpage that deals directly with DEM technology at www.applieddem.com

If you need anything else or have questions that I can maybe help you with or application and problems that you might need help with please fell free to contact me directly.

Best regards,

Grzegorz "Greg" Dewicki

Overland Conveyor Co., Inc

Applied DEM, Inc

303-716-0569 - Direct

dewicki@overlandconveyor.com ■

There is no magic involved in dust control at truck dumping stations. If you are tipping through a road grid, you need Burnley baffles below the grid to contain the displaced air. A dust collection system can be sized for the surface area of the grid (cu.m/h per sq.m) with appropriate allowances for dustiness/fineness. A properly designed ducting system willl not block and wear can be minimised. Unfortunately, you do need a baghouse and that costs money. However, proper sizing and selection of an appropriate design will minimise maintenance and operating costs.

The design of the hopper and the duct connections is CRITICAL to successful operation (exhaust is from below the baffles). You must ensure that the ducts cannot be blocked at the hood entrance because truck drivers will always overfill the hopper above the road grid. A drive-through arrangement is best for efficiency. A roof and side walls to exclude weather and minimise wind influence is also essential.

Dust suppression using water sprays will not work in this case. Fine mist is easily dispersed by light drafts. Once the dust is airborne, it is very difficult to knock down.

Michael Reid. ■

Dear Sir,

please have a look to our

www.vsr-industrietechnik.de

and contact me directly if you are interested. ■