The legalities are beyond the scope of these forums.

Your quest to carry burden under cities is no more complex than the topic of building passenger carrying trains under coastal cities. Quite a lot simpler in fact. You'll just have to grease the right palms, legally referring that is.

In most countries the ground below a certain depth becomes state property. Crown property in the UK. In India that might be a useful legacy.

Use the argument that you would be taking trucks off the road & you'll be home & dry. With adequate pumping of course.

Companies are still laying gas mains under cities in parts of Europe & elsewhere, What's so hazardous about a conveyor?

I think its a very good solution & wish you every success. ■

John is correct in everything he is saying but the problem of maintenance remains the Bengal Tiger hiding in the gallery as he would agree.

The City of Syracuse, New York USA as an example had a belt conveyor under the city delivering soda ash from a solvay process plant to a soap manufacturing plant for many years. If I remember correctly it was blasted out of hard rock as it(hard rock) is close to the surface.

Its fine to want a twin conveyor system in one tube- will you parallel each belt installation or will you have one belt suspended over the other?

will it be steel supported or wire rope supported with the sailboats bolted to the roof of the tunnel segments?

Belt training becomes a huge issue along with cleaning spills and the proper installation of emergency stops and foundations for drive units and tail pulleys. How many transfer points are involved?

The problem of maintenance, egress, and ventilation remains, will you build a tunnel large enough(15 meters) for vehicles to transit the entire length fully laden with equipment for repairs and carry rolls of belting and idlers to repair belts or will you simply splice good belt to bad belt and replace the entire upper and lower carry back and return segments?

What about turning around space for vehicles or will you simply make it rail tunnel with an overhead pantograph? What about water ingress and pumping requirements and distances?

Will you have a dedicated space for power and communication and exhaust ventilation runway in concrete segments set in the floor and have a narrow gauge railway on top of it?

Will you use one drive unit to power both belts in unison or twin drive units; for that matter how many drive units will you require and will you have galleries for the drive units and transformers themselves?

With a capsule pipeline you have a tube inside a tube(I know here we go again) that would handle the amount of ore moved from a to b with no need of conveyor components.

One begs to ask? John is this is another fishing expedition? ■

Dear Shri Rekhawar,

Many mines have underground conveyors. So, underground conveyors is not a new thing. If one wants to take conveying route underground he has to make a techno-commercial study and find out the economic benefit with such proposition. Running a conveyor on ground or over ground is economical compared to having it underground or below sea bed. Particularly one has to also see the maintenance aspect.

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.

Pune, India.

Tel.: 0091 (0)20 25871916 ■

The Chicago Tunnel might be a good example of boring under the city and installing a conveyor or two. The conveyor had a finished length of 15 km long. The tunnel was cut using a TBM. I forget the diameter but about 10-12m. This diameter was enough for 3 or 4 conveyors. Someone said use a 15 m tunnel diameter. Folly, foolish and wrong.

The Chicago tunnel was developed as an effluent surge tank. The conveyor was only used to evacuate the tunnel boring spoil.

Your two conveyors could be mounted piggy-back like the UK (Gladstone sic) incline. This system was the predecessor to Selby. The tunnel was from ancient memory about 4.5 m diameter. The belt was also about 1400mm.

Since this was bored with a mechanical rock chipping machine, there was no surface habitat or other street side difficulty.

However, blast and you may receive a strong notice not to. This depends on how deep, how competent the rock et al. ■

I note that the final flight to the surface, at the Chicago project, was a Dos Santos Sandwich-Belt High-Angle conveyor, 1372mm (54") belt width, lifting the TBM muck vertically, 70 meters (230 feet), up a vertical shaft.

Joe Dos Santos ■

Yes Joe, it worked well, unlike other coveyor parts of the project not related to your supply. ■

The Chicago project was troubled, largely due to overly optimistic expectations, on the Contractor's part, and poor conveyor analysis and execution on the supplier's part.

Very early, the interface of underground moisture coming up to freezing conditions on the surface, caused the vertical sandwich belt system to turn into an ice cycle at the shaft collar. Cladding after the fact, fixed this problem.

On another occasion they inadvertently ran a TBM cutter motor (100 hp or maybe even 200 hp, I forget now) up the sandwich conveyor. It did some damage but the sandwich system did deliver it up and spit it out at the surface. The repairs were minor and the unit was quickly put back into operation.

The disgruntled customer began to monitor the entire conveying system very closely in support of their intended legal action against the supplier. Weekly monitoring reports were issued for many weeks. I do recall, proudly, that during every monitoring period the Dos Santos sandwich belt high-angle conveyor was the best performer in the system. It had the most consistant production (never the bottle neck), the best up-time and the least cost in upkeep. This even in comparison with some mondane conventional stacking conveyors at the surface.

Joe Dos Santos ■

Can someone please give me some advice on tunnels?

I am looking at a 8km horizontal tunnel from ROM and primary crusher to a copper concentrator. (the tunnel will be up to 300m below natural ground level)

Two conveyors in the tunnel 1.6m wide and 2m wide conveyor belts doing 6000tph and 11,000tph

As there is no lift on the conveyor i can do it in one flight. There will be no drive/transfer stations underground .

Im thinking i could either stack the conveyors and have an access rd on both sides of the conveyor or keep the conveyors seperate and only have access between the conveyors. There are problems advantages and disadvantages in each.

Does anyone have any guidlines as to what diameter tunnel i would need? I need to establish a price to compare with overland cut and fill costs.

Do the tunneling machines have to be a circular profile. I have seen photos of conveyors in rectangular tunnels?

It would be great if someone had some examples of any similar projects.

Thanks

Peter ■

This one suggests that you are running 11kt out to the concentrator & returning 6kt to the pit as backfill. If so why not carry the backfill on the return strand? ■

No the waste is from the Mine (Ore which is too acidic). Both the ore and the waste go through the tunnel in the same direction. THe waste dump is 3 or so km further on from the concentrator.

Appreciate the quick response.

Thanks

Peter ■

Originally Posted by 450GASGAS

No the waste is from the Mine (Ore which is too acidic). Both the ore and the waste go through the tunnel in the same direction. THe waste dump is 3 or so km further on from the concentrator.

Appreciate the quick response.

Thanks

Peter

An underground tunnel for a conveyor at depth is of course somnething that can be done.

As John Gately would say the devil is in details;

As a former miner involved in tunneling it is a long time consuming process in many ways for may reasons.

Budget, Budget, Budget, Geology, geology, geology, topography, topography, money available for unexpected problems like rock gas or water ingress.

Unless you are fully aware with existing geology reports with existing core samples it is a daunting task as:

Core samples must be taken to below operating depth to determine the proposed routes geology at depth to determine the actual geological conditions at depth any water ingress per the geology rock hardness or overburden cover.

A conveyor belt tunnel will require fire supression along its entire length, forced draft and induced draft ventilation for fresh air ventilation, gas monitoring, explosion proof lighting, access elevators and ladder escapeways

You have not mentioned if there will be a decline entry portal and incline exit portal for the belts. both the entry and exit will have to be sealed off from entry with fences.

Rain water will be required to be diverted away from the tunnel portals and any water collected in the tunnel will be required to be pumped out of the tunnel to prevent hdrogen sulfide gas.

==================================================================================================== ================================

Tunnel design and excavation:

1.It will depend entirely upon the local geology to determine the tunneling method

2. read number 1

3. read number 1.

Hard rock tunneling methods

1. Hand driven drill and blast

2. drill and blast with rail mounted machinery and muck cars.

3. drill and blast with trackless machinery

4. single boom road header with rubber tired scoop trams or end dumps for underground use

5.double boom road header-same as above

6. sheilded tunnel boring machine with a single boom cutting head inside the sheild- the sheild also gathers the tunnel muck/spoil to be removed to the rear of the sheild.

7. tunnel boring machinewith a support and muck train with larger diameter tunnels.

8. micro tunnel boring machines for small diameter tunnels

Tunnels must be supported, meshed and roof bolted prior to advancing the next round

roof bolting is done by hand drilling or mechanical roof drill

Many small tunnels bored with small tunnel boring machines and micro tunneiling boring heads are advanced with a hydraulic sled in a launching pit which attaches pipe behind

the cutter head the attached pipe conducts the tunnel spoiul to the launching piut with augers or it is pumped if the tunnel spoil is liquified using clays to allow fast advance along

the tunneling route.

Roof bolts

larfger tunnels require mesh, shotcrete and roof bolts to supprt them

roof bolts are either mechanical roof bolts with a threaded shell anchor

cable bolts with resin cartridges to anchor both cable bolts and resin roof bolts

A tunnel may require shot creteing lining the tunnel with shot crete to seal its surface if water is encountered.

shot creting requires a comoressed air gun to spray the mix with a binder medium to create a concrete barrier.

larger tunnels may have very competant geology that is very hard and require no support

large bore tunnels are typically lined with gasketed concrete segments to seal the tunnel bore.

These tunneling machines have trains which transport tunnel segments and use a hydraulic arm to install the tunnel segment.for the entire diameter

which may exceed 45 feet in diameter as amater of common occurance with advances in metallurgy and TBM design, these machines

are also tasked to install roof bolts and roof mesh during the initial boring prior to the installation of the tunnel lining segements

The tunnels bored in this manner also have concrete or bentonite pumped behind the concrete segments to seal the bore against the concrete liner as well.

sheild bored tunnels either round or rectangular have a moveable form works trailing directly behind the tunneling sheild which acts as a roof support and a concrete form worlks to line the tunnel bore in one pass.

shallow tunnels are created using cut and cover methodology while installing box culvert sections at shallow depths as well

I would strongly suggest you search the various tunneling magazines such as world tunneling-first in its field and visit the japanese tunneling associations web site.

Mr. Lawrence Nordell has experience involving belt conveyors in tunnels in many situations as well.

I hope you had the opportunity to read my PM to you regarding this question

leon ■

Hi Leon

I appreciate your detailed response. I know there area many variables that have to be considered thanks for pointing so many of them out.

I have some core samples around the area. so i will probably send the reports to a tunnelling crowd to try and get some further info. This is just a study so far to work out potential options.

I was hopeing that somenone would be able to answer my questions about the diameter of the tunnel and what access is required????

The reason why i am investigation tunnels is because of the amount of cut and fill required to on top of ground. Also inital designs are suggesting batter slopes of 35 degrees . The area is so mountainous and undulating that the costs for teh cut a fill are staggering and the tunnel needs to be investigated.

My first priority is establishing the size of the tunnel.

THanks

Peter ■