Originally Posted by AussieBob

I am a university student. I am researching the possibility of using HAC to haul crushed waste material directly out of an iron ore mine open pit.

The pit walls are at 45 degrees.

What is the longest HAC that could be achieved? I am looking at requiring between 600 and 1000 m of HAC (several units in series would be fine of course).

Also, what is the maximum throughput that could be acheived? I am looking at requiring 12,000 mtph to 16,000 mtph waste production.

All help is most appreciated

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Uh huh,

they used make our summer co-op students inventory electric motors to keep them occupied all summer.

The smaller you break it the less space it takes up you know.

So your intent is to have flights over the mined benches to the gob pile?

how stable are the benches? are you sure you will not have to anchor and mesh them to maintain stability?

what is the waste overburden wieght per cubic meter?

Do you expect to use an in pit crusher to break it to minus 4 inch material?

Where is this gob pile and how far overland?

are you simply dumping it to reclaim it and dispose of it with a matched loader and truck?

you may be better off just trim shooting a trench line to obtain a 21 degree incline out of the pit across the benches shooting from the top down

to obtain the 21 degrees of incline and buy a belt from mssrs. Dos Santos and Nordell.

You failed to mention if the bottom of the ore reserve has been reached or if you are simply stripping gob.

Unless you use sandwich belts from mssrs. Dos Santos and Nordell,

you will not have a lot of options unless you look at using a Pneumatic Capsule Pipeline

loop system from me.

My two cents anyway. ■

This is a second or third posting in reply. I am not sure if the others will turn up as well.

The specifications noted:

1. 12,000 t/h

2. Lift 600m at 45 degrees

3. Can a HAC or Snake do it?

First, you need more information about the product density, lump size, et al.

Second, neither of these can do, in one belt, what you want to do.

This hypothetical belt would need to be over 2500 mm wide, have a belt strength of ST-10,000 N/mm. Only Veyance Technologies (Old Goodyear Industrial Products) has achieved a splice endurance limit of 50% with ST-10,000 N/mm at > 10,000 load cycles on a destructive test program.

The belt speed would need to be near 6 m/s or above 5 m/s or you would need two product streams, if the lump size was crushed below 100 mm.

The power of this one belt would exceed 20,000 kW. Even with two belts you can see you are way beyond the limits of a HAC or Snake.

Beyond these limits are the lift limits. Neither is suitable for tranfering the product on a 45 degree slope. With the high tensile rating, you could not bend the belt from a 10 degree loading angle to 45 degree in a reasonable space.

Since this is just a academic exercise, I will stop here and let another offer more wisdom. ■

Having said the above, a Power Strip concept could overcome the limitations of a single belt lift, by separating the carry belt from the tensile belt. Then the single lift could be accomplished.

The POWER STRIP can lift about 200 m / drive station with a ST-10,000 N/mm tensile center belt rating. Thus, you would need a mininmum of 3 drive stations, but no intermediate transfer stations to lift 600 m in one belt system at 12,000 t/h. You will still need to carry the product with a 2500 mm belt and have a cover belt to control rollback.

The POWER STRIP would rest on the center idler in a 3-roll configuration. ■

Aussiebob,

Running up a 45 degree slope does not allow for a transfer station. As previously stated, you must reduce the loading slope to no more than 10 degrees.

This means you must install a substantial concave vertical curve to control against buckling. Its concave radius would not allow a manageable loading station configuration. ■

Originally Posted by AussieBob

Okay, some extra information that might clarify.

Bench height is 15 m.

Removing overburden only.

Will be using an in pit crusher to reduce material.

What I want to be able to do is, by using an in pit crusher and conveyor system, combined with a high-angle conveyor, move the waste out of the pit. I'm looking at moving 16,000 metric tph of waste. The pit is at 400 m depth now and I need to get it to 700 m depth with this system.

How can I do this?

I don't know of any other mines that use HACs with such a throughput, and reading countless journal and other articles has turned up nothing.

Are there any examples of having one main HAC and adding additional lengths as the pit deepens?

Its no going to happen unless you drive a tunnel at a 21 degree decline slope to the horizon of the orebody and use a pair of 72-84 inch belts or:

a 24 inch PCP system with minus 2 inch run of mine sizing for the overburden in loop as long as the waste gob pile is 10,000 feet or more away.

A 22 inch capsule liner 144 inches long will transport 30 cubic feet of material rounded and using a cubic yard as a bench mark for the PCP possibly 2 tons or more per capsule liner at 98 percent efficiency traveling at 40 kilometers per hour to the gob dump and back.

using 275 tons per minute you need 135 capsule liners at a minimum for the X distance to the gob pile which you have not mentioned.

The greater the payload the more efficient the PCP becomes as the weight of the capsule liner becomes zero in tare weight in which the weight of the material is the only wieght being moved due to the 98 percent efficiency of the PCP system.

The finer you crush the gob, the more it wieghs, the more efficient the PCP becomes as the payload is used to its advantange in propelling the capsule liner which has a zero tare and the gob wieght.

You would need 4,000 feet of additional space to use a single pipe system for the empty and filled capsule liners to use a single pipe system for loading and discharge points-which would be better used for a loop systemas you have the room.

lzaharis ■

As a side issue to illustrate an example;

the kennecott copper bingham canyon mine-sorry if the spelling is wrong- they ended up tunneling into the pit because it was so deep and ran standard gauge hopper cars for ore /and side dumpers I think also for gob. I think that mine is closed now I believe sorry its been over 20 years since I knew of the tunnel going into the pit floor. ■

I believe Kennecott is still going strong. They have extended the mobile crusher deeper into the pit. Haulage is by belt conveyor from the crusher and trucks to the crusher. Deeper they go. Eventually, the mine will go subterrainian and do block caving or what ever.

I started feasibility studies on ore and waste transport, to replace the rail in 1985. After a year of scenarios, they eliminated haulage of waste to a crusher system and resorted to trucks. I together with Krupp finished conveyor design in 1986, commissioned the system in 1987.

There are other modern ways to do high incline. I have given methods in forum before. One flight to the top. Any height. ■

Dear AussieBob,

If you wish to see a illustration, I believe it could be arranged. An IP signing would be in order. There are some caveats, such as the maximum lump size should be held to 150 mm. Large is possible with penalties.

We would need to know the range of particle sizes and their % passings.

Further we would need to do a little FEA on the main members for these stress levels.

As I understand, you wish to take 16,000 t/h up a 45 degree face for 500 m lift.

There are other critical issues such as how to load and unload. Can these be on relatively horizontal planes (<10 degrees)?. How much real estate can we have to load the conveyor before lifting at 45 degrees and after cresting the lift?

You can further correspond directly to my email below. ■