Posted on January 18, 2000 at 16:25:15:

In Reply to: Skirt Board and Belt Scraper Liners posted by Rajesh Mendiratta on January 17, 2000 at 21:24:37:

We specialise in equipping raw coal mine belts, refuse belts and coal carrying belts in power plants with skirting and skirt board retention systems for transfer points as well as primary adn secondary scrapers, modular and single blade in a variety of sizes. In addition we specialise in pulley lagging both rubber and with porous ceramic inlays.

Please give more complete information on conveyor systems employed, sizes, speeds, whether vulcanized or mechanically fastened, head pulley drawings, transfer point drawings so we may advise you more precisely.

Sincerely,

Geoffrey L. Rogg

Legro International Corp. USA

P.O. Box 69

New Rochelle, New York 10804

tel: (914) 633-0488

fax: (914) 633-4427

e-mail legrorogg@topnet.net ■

Dear Mr. Rajesh Mendiratta,

It seems that you have written for the type of liners in chute, and type of scrapers to be used for coal conveyors.

1) Coal is not very difficult material for consideration of the liners, because it is low in density and average in abrasion.

2) You will find many materials suitable for the same, as suggested by the various respondents.

3) Important consideration is the availability, price, efforts needed to construct, and efforts needed during replacement.

4) Regarding suitable type of scraper, the opinions differ widely and so I refrain from giving any opinion. However, important considerations affecting the type will be whether the conveyor is unidirectional / reversible, and quantity of moisture / water in coal.

Regards,

Ishwar G Mulani.

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

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25882916 ■

We specialise in conveyor belt scrapers and have numerous installations in South African Coal mines.

Please visit our website where you will find a response form where we can more accurately help you with a solution.

Regards

Anthony Harris

Design Engineer ■

Hello Rajesh,

This is a good topic to explore. It has not been given much treatment by the standards community. Plants require significant maintenance to control: spillage, dust, deflagration dangers, noise, repair and plant resources to name a few.

CDI finds that the chute design, skirtboard design and belt cleaner types and placements should augment one another as I note below.

A short list of priorities that influence and interact together for chute, belt cleaners/scrapers, ore flow and skirtboards are:

1. Shortest drop distance between belts accounting for orientation of belt feed and discharge vectors and to achieve point 2.

2. Controling ore velocity to approx. match receiving conveyor

3. Feeding of fines into main flow stream before flow onto spoon

4. Valley angles should be as steep as is practical - must exceed minimum for fine, wet product to build up and account for cold weather.

5. Pass all lumps without restrictions and bridging - maximize exit opening at discharge into skirtboards - this requires special attention regarding point 8.

6. Primary belt scraper to discharge into main ore flow stream to assure chute is self-cleaning

7. Secondary belt scraper may not be posssible to discharge into main ore flow stream - thus, should max. valley angle - this concept favors the Hosch reverse rake type belt scraper vs the backward rake type.

8. Centralize ore onto belt which requires special geometry of chute curved spoon integrated with skirtboard

9. Special super low sliding friction liner material below secondary fines scrapers

10. Liners should account for abrasive conditions such as pyrite and stones. Hard or abrasive materials do not favor low sliding coef. materials such as UHMW plastics. In such a case, a carbon steel with a Brinell of +500 and 15mm thick with ni-hard, chrome or stainless is specified.

11. Skirt geometry should be self relieving of stones that work under liner edge.

12. Provide good access to install, adjust and inspect skirtboard seal assembly

13. Provide good access for inspection and replacement for chute and skirt liners

14. Provide proper control of dust and skirt seal system

Many of the above are not treated properly by designers. A new class of chute geometries are emerging based on the flow simulations using DEM. Materials of construction, manufactured products such as scrapers and liner materials are being more efficiently utilized as we understand the ore flow dynamics and resulting wear conditions.

Thanks for the good question and hope it stirs more input.

Lawrence Nordell

Conveyor Dynamics, Inc. ■

Dear Mr. Rajesh Mendiratta:

A question for you - are you looking for replacement rubber, or other material, seals for existing skirting systems and cleaners -- or are you looking for new skirting systems and cleaners?

If you need new skirting systems, there are a number of good systems on the market (Martin Engineering, Rema Tip Top, etc.).

If you need quality belty cleaners for coal, there are a number of quality systems available.

In both cases, your system conditions will dictate which alternative is best suited.

In general for skirting systems, I prefer a dual rubber skirting system - one that contains both the larger materials and the fines.

In general for belt cleaners, I prefer full face rubber or urethane primary and secondary cleaners that have self-adjusting tensioning mechanisms. Also, wash boxes are useful as tertiary cleaners for muddy applications.

Although there are similarities from conveyor to conveyor, each conveyor is different and what works for one system may not work for another. You would be well advised to discuss your specific needs with your local suppliers (those who can effectively evaluate your needs and who can respond to your problems).

If you need guidance on the various options open to you, feel free to contact me.

Regards, ■

Posted on January 19, 2000 at 02:25:23:

In Reply to: Skirt Board and Belt Scraper Liners posted by Rajesh Mendiratta on January 17, 2000 at 21:24:37:

We line skirt boards with poly tiles which are particularly suitable for the coal industry due to their high wear characteristics and tear out strength. (They are also a light weight alternative to ni-hard tiles).

Hosch is the world market leader in belt scrapers and tracker rollers and we have extensive knowledge of the coal industry world-wide.

Please advise more detailed information of the conveyor systems you have employed, whether the belts are vulcanised or mechanically spliced plus drawings of the head pulley and any transfer points. This additional information will allow us to establish a more precise solution for you.

Lara Dunne

Marketing Executive

Hosch GB Limited

97 Sadler Forster Way

Teesside Industrial Estate

Thornaby

Cleveland TS17 9JY

England

Tel. 0044 1642 751100

Fax. 0044 1642 751448 ■