Dear sir,

We have experience in many projects across all cement industry in Europe and world wide.

We believe we can handle the problem which you did described.

We have measurement equipment to measure necessary data for calculation of the angle of belt – for aerated and de-aerated cement. This instruments – the SHEAR TESTER type RO-300 – is used by all leading cement industry. We also give each year a course “ QUALITY CONTROL AND POWDER TECHNOLOGY “ in which we handle the problems in cement industry – see forum seminars.

An general impression of our field of activities you can find in our website – WWW.IPT-ONLINE.COM - . please contact us if any question.

IPT Industrial Powder Technology

R. Wohlwend

Tel + 4232376344

e-mail iptvaduz@aol.com ■

To my knowledge there is no incline angle at which you can convey cement. Even if de-aerated material disturbance during conveying will cause it to fluidize and run like water.

Joseph A. Dos Santos, PE ■

Dear Mr. Gupta,

Referring to your question :

1) Dunlop UK Mentions permissible inclination 20 degree for portland cement and 10 degree for aerated portland cement

2) Indian standard IS 8731 mentioned these values as 20 - 23 and 6 degrees respectively

3) CEMA mentioned 20 – 23 degrees for portland cement

The above values must be on the basis of observed field results. I suggest you to take feedback from cement plants also. There are many cement plants in India and you will get / see factual data.

Regards,

Ishwar G Mulani

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

Email : parimul@pn2.vsnl.net.in ■

Dear Mr. Gupta,

The answer depends on the state of the consolidation stress, interlocking of particles, and special physical events that may induce or inhibit flow. As others have noted, when aerated, such as, at the loading point, the product will flow like water. Some say even more than water sighting an example of passing fine portland cement through a sieve that water will not pass.

When consolidated, like in the transport bag you open, the repose angle is very steep due to the particle interlocking and non-Newtonian mechanics at play.

Product, in transport, can under go consolidation. It takes time and work to expunge the entrained air. When will the transport angle exceed the dynamic angle of repose?

So there is no one answer. The problem must be explained in sufficient detail to allow a more prudent response.

Lawrence Nordell

Conveyor Dynamics, Inc. ■

I repeat, there is no angle at which you can convey dry bulk portland cement. This is from experience.

At the advice of a colleague, after watching cement flow like water from the loading hopper to a troughed belt we allowed the material to sit on that troughed belt, in still condition, over night. The next morning we ran the belt and the cement on the belt still flowed like water.

Joe Dos Santos ■

Dear Joe,

an angle of about 8 degrees was no problem, provided the material was fed onto the belt properly.

Holger ■

Dr. Holger,

As you can tell from my comments, I don't share your experience of success with cement. Since others agree with you then there must be a way to settle the cement so it doesn't fluidize. I don't know such a procedure. Will you be so kind as to share this with the readers of this forum.

Thank you.

Joe Dos Santos ■

We have studied the transfer and loading process of fine cement and coal using DEM. We have studied field conditions and believe there is a chute configuration, which differs from conventional configurations that does not aerate the powder. We are negotiating to install this concept in cement plant in India.

DEM modeling shows that most chutes create one or more hydraulic jump effects that induce aeration. This condition is difficult to observe due to dust and general turbulence. However, a fine granular DEM stream simulation illustrates this condition. Reconfiguring the transfer geometry can eliminate the hydraulic jump(s) and other unwanted turbulences. The change in geometry is not subtle.

We have studied typical dearation. This is a very non-linear phenomena. About 60% of the gas is expunged in about 2-4 meters or about 1-2 seconds depending on the transfer loading process. There after, the process is slowed. Another 10-20% is expunged in another 100 meters.

Most of this gas bulking can be eliminated with a new geometry and liner system.

We are happy to discuss this process with interested parties.

Lawrence Nordell

Conveyor Dynamics, Inc.

website: www.conveyor-dynamics.com

email: nordell@conveyor-dynamics.com

phone: USA 360-671-2200 ■

We did supply troughed belt conveyors with incline. The permissible degree depends on the proper design of the feeding area. These conveyors have been running properly now for years. ■

Dr. Holger,

Please advise at what inclination angles you were able to convey the cement.

Joe Dos Santos ■

Gents,

This is a relatively simple question and there is no reason for a quick answer rather than seek "consultants" business.

If U are conveying ordinary portland cement, U should be able to do 12 or 14degrees at a reasonable low speed ie < 2m/sec.

Depending upon the loading arrangement - suggest de-aearation screws - U will need a good section of flat belt to settle down the cement ie further de-aerate it - for this reason, the idlers are rel. good a rocking and settling the cement.

We also convey fly ash at these angles with no real dramas other than dust collection/carry back at transfers.

Thanks

James Morrish

Engineering Manager

Cement Australia - Gladstone ■

I have seen belt conveyors conveying Portland cement, in cement plants.

Further to information from Mr. James Morrish, additionally, how about using UHMW polymer liners or stainless steel liners, in a zone of approximately 1.8m height, near hopper outlet and installing chute vibrators near the discharge mouth of hopper? This can possibly result in steady flow from the hopper outlet and less aeration. Erratic flow from hopper outlet will cause formation of air cavity within the flow stream and consequent turbulence / aeration.

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 ■

Dear Joe,

I do not understand why U have had bad expericnes with conveying angle.

We use a grinding aid to get more prod. from the mill - this is basically a fluidiser agent...(and a very good one too)

Still, we do not have issues at all...pls refer my last post.

De-aeration screws

Low drop height

"Rocking" idlers if needed

Low belt speed.

Forward speed at loading point

Easy Campese mate

James Morrish ■

We have experience of Cement conveying on belt conveyors and upto about 9 deg inclination we have conveyed cement successfully at 3 different applications.

For cement conveying it is must that cement is fed on conveyor very gently preferably through a rotary air lock. At feed point conveyor should be horizontal and later on you can provide inclination with about 150 m radioous of curvature. The speed of conveyor should also be restricted to 1.0 m/sec.

If you require any further details please contact me.

JPGupta

Holtec, Gurgaon ■

We handled up to 11 degrees.

Holger ■

Dear sir,

We charge vessels with cement and clinker using 44 meter belt conveyor,

the inclination angle is 45 for toughed belts, 28 for smooth belts,

we manufacture these belts ourselves.

you can see some pics of belt conveyors.(last 2 pics in belt conveyor section)

at our site :-

http://www.amerya-metal-industries.tk

Best Regards

M.Khalifa ■

Dear sir

Ihave seen many installation in cement plants. Cement conveying is typical specially when it is hot

At loading point conveyor should be horrizontal in case horrizontal profile is not feasible angle of inclination should be restricted to 5 degree only.. after loading point angle can be increased to 12 degree

Speed of conveyor should be preferably !.0 m/sec or max you can go up to 1.5 m/sec

A R SINGH ■