Conveyor Dynamics, Inc. (CDI), USA, designed and commissioned a 20 km overland coal conveyor in February 2007 together with Laing O'Rourke (LOR), Australia. It transport coal at 2500 t/h.

CDI designed and commissioned a 16 km overland in Zimbabwe in 1996, together with E.L. Bateman. We have many in the 10 km range, starting with the MICARE 9km, Mexico in 1980, and 20km Channar 1989.

The industry is more comfortable today with the technology of long overlands.

Yes, the 12 foot pipe could inclose the conveyor. Mnay conveyors are installed in tunnels. The methods and maintenance equipment clearances need to be considered.

Conveyors can transport on 15 degree inclines. Are you considering a 15 degree incline for 15 km? That could be a little more of a challenge. CDI together with Krupp, Canada, designed and commissioned a 12 km downhill at 11% slope, regenerating 25,000 kW in 2000. ■

Can we aid in its design?

As you can see we meet the criterion of having done this before. You will not find a firm or consultant that can beat our technology for your application.

Contact details are below. Visit our website. If you wish to see 20km reference installations in Australia, we can accomodate. ■

A key to good tunnel conveyor design must address safety, maintenance and fire. Following are some considerations.

We designed a under the sea tunnel conveyor for BHP in Australia in 2000. In this, CDI provided a design for fire suppresion.

Any tunnel has special maintenance issues which are unique to the enclosures. Noise is a problem. Belt can flap and resonate with excessive noise if critical belt speed and idler rotation frequencies are not designed properly. Finding faulty idlers with the high noise background needs special design attention. Changing faulty idlers, et al.

Clearance under and around structural supports should be handled differently than with overlands.

Our tunnel experience includes:

Key issues: 1) hang from ceiling or support from floor. 2) maintenance vehicle design, or provide alternative, 3) ventilation needs special attention, 4) dust may need to be controlled with higher speed belt and its wind erosion, 5) ...........

1. Palabora open-pit slope belt in rock tunnel, in 1988, from crusher to surface plant

2. Palabora underground mining rock tunnel slope belt, in 2001, with special tunnel structural supports and dust control -

3. BHP under the sea sloping: down - horizontal - incline with drives at both ends

4. Los Pelambres 12 km rock tunnel conveyor

5. Island Copper 1 km rock tunnel slope belt (decommissioned)

6. Amplats man-riding rock tunnel conveyor

7. and many more. ■

We have also worked with conveyors in pipe or pipe like tunnels such as:

1. Cypress Moly Mine in Chalice, Idaho USA covered for avalanche protection.

2. Chicago Tunnel - 15 km tunnel boring conveyor.

3. Also note that all underground coal and other mineral mines have similar issues. ■

On the issue of fire:

1. flame retardant belt is possible - usually has much shorter life span due to compounding

2. Prevention - seize resistant bearings

3. Detection - as is used in some coal fire power plants - zone sensors for smoke, heat, .....

4. Suppression - foam zones, water injection manifolds, ....

Many of the same issues that are addressed in underground coal mines.

Is your coal have a likelyhood of spontaneous combustion? Is the coal coming from a ship? Can it have unexpected heat build-up from the transport storage? If so, the belt will need special specifications.

I will let others respond beyond these comments. ■

Dear Sirs,

What I am able to offer is a 'Conveyor Idler Assembly' patent application for the worldwide belt conveyor applications. It allows the possibility of idler roll maintenance on live operating conveyors. To appreciate my concept, please feel free to visit the website http://www.tamecservices.com.au. The assembly also allows the conveyor to be blindsided against one side of a pipe, gallery or factory wall as all maintenance is completed from any single side, as in the underground coal headings maingate, tailgate, trunk conveyors where the off walk side is against the rib with absloutely no access to that side. It is also ideal for stacker ramp conveyors where there is only a single walkway.

I have been involved with the installation and maintenance of conveyors over 10km in length in surface and underground applications when I worked as a conveyor technologist many years ago. Length of conveyors is no longer an issue with one I heard about in China measuring approximately 100km in length in a single flight. Conveyor dynamics become a lot more challenging when there are assending and declining sections within the same flight as the regenerative declining belt has to be accommodated with braking forces. ■

The jetty sounds very interesting. What fall is envisaged from the unloader deck down to the seabed? Over the descent run the tube will have to be braced against the shoaling forces etc.

12' is about 4m. The Channel Tunnel between Great Britain & France is 8m diameter & struck through chalk which although soft is a lot more substantial than a seabed in terms of support.

Is a trenching plough for 4m available? Is there going to be enough overburden depth to stabilise a pipe that size?

Alternative tunnel boring is quite straightforward, I've worked on the Channel Tunnel 13 car backup train. One of the major issues is controlling the inrush & you will have quite a bit to contend with unless you undertake extensive shaft sinking & construction at the jetty end/emergence zone. Even then!

Trenching or tunneling for a pipe that size is going to be expensive. Who will fabricate the pipe? From what material?

You should consider the onshore facilities necesary to expedite such a job & compare them against the cost of a simple piled pier carrying a pipe conveyor. There won't be much in it...except for the peace of mind. ■

There you go always breaking new ground, 15 km pipe conveyor at 1500 t/h not saying anything with lump size. Who is endorsing a pipe conveyor?

Let's talk real conveyors. No problem with 15 km and 1500 t/h on jetty or under. Let's stop smoking the pipe.

I do note that thread starter has not responded to recent dialog. ■

When a pipe along a seabed is being considered the conveyor mechanism is a bit irrelevant. I just mentioned a pipe conveyor(s) because it(they) would be better in the offshore winds if they ran over water.

Under water; the constructor is faced with the option of taking tunneling spoil out on the final belt, thereby stuffing commissioning criteria from day 1, or buying two belts to satisfy the conveyor supplier. Ventilation during construction is just another overhead for the punter to pay for. In retrospect the fitting out requirements automatically kick trenching into touch because trenched pipes do not have internal fittings, remote pigging apart.

So the tunnel is the only underwater option: which will be safer but require a bit more lift. Of course it will have to stay in bedrock which does again require input from the thread starter.

Breaking new ground.....I'll admit it's not the only thing I've broken. Cheers ■

BHP tunnel drilled the sea floor on referenced conveyor and found incompetent stata which leaked. Big problem. If I remember correctly they lost the boring machine or darn near. ■

If you wish to recover the TBM you have to build a first class vertical water tight caisson in which you either start or finish the tunneling in order to save the TBM. An expensive and difficult undertaking. ■

Or converting incompetent strata to high strength using bonding materials like cement. Worked effectly to stop a 33ft diameter 4200 tonne Robbins TBM from an inrush of mud in front of the cutter head which had the potential to completely bury the tunnel for a kilometer on an 80 metre decline drop.

The process took 24 hours preparation per 5 metre advance after which the process was repeated until the incompetent section of strata was penetrated successfully using the TBM cutting process. The tunnel wall remaining was also competent to more than a metre. Freezing will work but does not hold longer than the time for the strata to thaw.

Vertical shafts through a 13 metre sand / water underground aquafor failed to be penetrated using freezing but a 54 hour preparation using cement powder and water pressure solved the issue. ■

What refrigerant & refrigerant load would be appropriate to freeze tropical brine?

We respondents are well on the way up a learning curve, with or without the harbourmaster. ■

Hi Lyle,

I was in Mongolia, Phillipines and another location was New Zealand as well as local mines when we used slurry powdered cement injection using water pressured assisted pumping and a hell of a lot of 1" air/water pressure lines which were grouted into the surrounding area to relieve the water slurry extra volumes we feed in. When the cement colour started to flow out of the face hose tails away from the feed lines, we simply bent the hose tail to stem the flow and tied off with wire. The cement was then allowed to set before pressure cutting commenced again, with the process being continued until 'soft strata' appeared some 3 - 5 metres advance and so on.

Oaky did indeed dig out their longwall chocks as the whole competent rock just collapsed into the goaf taking the access headings with it. ■

It would be handy if we could ask the monks at Culross how they managed to build an offshore loading station direct from an undersea coal seam in the Firth of Forth. Some say it was developed by the local land owner, a Mr Bruce, but the local records state it was designed & built by the nearby monks.

An offshore island was built to house the vertical masonry lined shaft & a horse driven bucket system provided the drainage.

They must have had some powerful software back in 1575!!!

Obversely, one of the drawbacks of monastic celibacy is that there were no descendants to emigrate towards todays mineral deposits. ■

are you still looking for consultants in india to develop this design. Please contact us at

S.M.Consultants

B.S.R.Moorthy

9444818826

Chennai

We have 15 years of experience in conveyor design and would like to talk to you regarding your project. ■

I hope your diving gear isn't 15 years old! Good luck though. ■