Carrying on both strands is done quite regularly. Your post does not say how far you expect to run with the different materials. You need length for the turnovers and so you need to be talking over a km to make it worth while conveying on both strands. Perhaps you can get away with a couple of discharge points in the port but you will still have a complicated distribution network inland. Under a km and I wouldn't consider. I am working on 2 twin strand conveyors now. One is 10.2km and t'other is 8.8km and even then it is only just worth it because the adjacent workings are getting in the way all the time. ■

Hi,

We have undertaken the design of a number of two way systems and are presently working at GCW in India.

So there are references on your door step.

Kind regards

Phil Staples ■

Hi there..

There is a long one at Port Hedland in Australia, which carries iron ore in one direction and clinker in the other (I think)

Then there is our Dual Carry Conveyor here in South Africa at Namakwa Sands.

Ours is 7km long at present and handles 1000t/h+ of tails in one direction and 1500t/h+of mineral sands in the other.

We probablywill upgrade it to 1800t/h

Cheers

LSL Tekpro ■

I do not have much to contribute to this thread, but, you asked.

Port Hedland transports 4000 t/h of iron ore medium fines on the carry strand and up to 1000 t/h of hot briquettes (<120C) or HBI material on the return strand. I will try to post a screen shot when I figure out how to load it. It is drive by head two 900 kW at its two head pulleys and one 900 kW drive at its tail. The starting control a Voith Drain Couplings. The conveyor has one horizontal curve about midway.

I will post the basic specifications once I retrieve the phote.

We do have a number of pipe conveyors with bi-way transport.

Gram:

I thought your South African bi-way was copied after Port Hedlands. Was that you and the other Gram that I saw climbing onto its structure with cameras a-snapping? ■

Thanks Lyle.

Not much left for me. ■

Indeed, Larry..

It was myself and Graham Shortt that you came across on the Port Hedland dual carry conveyor.. all those years ago.

I must add though, I did not copy that one at all. For a start, it had 22 pulleys!.. far too many, and more steelwork in it than the Forth Bridge.

My one has only 10 pulleys, which is not bad considering that four of them are drive pulleys.

Also, for the first 3 years of operation, I had to run it with a belt swop over system along the route, to change the top strand to the bottom and vice-verca, through a roller coaster.

The conveyor is doing well after 10 years of operation with very high availability considering it runs through a sand dune area, and was extended to nearly 7km long some time ago. It will soon be uprated to 1800t/h in both directions.

Cheers

LSL Tekpro ■

Two way conveying is not uncommon. Some years ago we did the engineering of a two way conveyor that carried limestone on the upper strand and clinker on the return lower strand. This system is not particularly long (2.8 kilometers) or high powered (1200 HP = 895 kW) but it is impressive as it incorporates all of the high tech features in the industry including:

• A smart (target tension) booster drive on the carrying side
• A natural booster drive on the return
• Belt turnovers
• multiple, optional discharge points along the return
• Irregular path featuring eleven (11) horizontal curves

Joe Dos Santos ■

Dear Graham,

If not for Port Hedland, would the RSA bi-way have been built? Most conservative miners only venture forth with some one else's risk gone sucessful. This of course is retorical. I respect your ability to apply only 10 pulleys. I do not recall the 22, but, do agree pulleys should be used sparingly or not at all. The heavy steel specifications were the product of the clients criteria in a seaside zone with corrosive iron ore dust, including the highly active HBI.

Anyway, I cheer your sucess. Keep it up. ■

Dear Joe,

I know a long time ago, we discussed the bi-way conveyor you have referenced. Did you know Mr. Andrew Jennings, Patrizio Perrone (client) and Jean-Luc Cornet published a paper on some of the upgrades to this installation at SME 2012?

The paper notes only some of the changes:

1. Stop most of the low tension pulleys from breaking, requiring pulley redesign and rework of the gravity take-up

2. Stop the belt for repeated catastrophic failures, belt suffered from repeated (+1000) rock punctures.

3. Rebuild the take-up system so that it would properly function,

4. Design a new belt construction with a different splice pattern, including improving the thermal capacity of the clinker

5. Rework the control system that never allowed the conveyor to operate to its design tonnage

6. Rework the booster drive load cell system

7. Belt turnover rework

8. Reworked the chute designs

I do not make these points to impune your design ability. I highly respect your capabilities and what you have done for our industry. I note them to give pause when attempting very complex conveyor system. It is probably one of the most difficult systems to get right build in the USA or anywhere in the world. We were fortunate to have the roll model to work with. It is much easier to fix/retrofit than to design from a blank page.

I hope this note finds you in good health and hope we can keep in touch. Please call to further any queries you may have including a copy of the paper. ■

Larry,

Thank you for your comments. No offense is taken. You may recall my account and the circumstances of that project.

The project was begun without us and ended without us, unfortunately. My client began this project with their long time European partner, that provided them with the analysis and recommendations. That relationship began to falter when the European partner could not handle the two-way conveying as their software could not handle the return strand for carrying a material load. Initially My client would ask me to analyze certain local aspects of the conveyor. He was basically running a check on his European partner in areas where he doubted his analysis. After several incidences of this type of interaction my customer basically abandoned his partnership and handed over to us the entire analysis of the conveyor. We utilized our ExConTec complete analysis program to analyze the system under all operating conditions. This was lots of fun as there were some 32 distinct loading conditions (loading discontinuities etc) that played a controlling roll in some aspect of the conveyor design.

Our analysis provided the basis for the equipment design, that is, power, belt tension, tensions and departure angles, at pulleys, etc. The scope of our work did not include the design and selection of any of the the equipment. Unfortunately, we played no controlling or advisory role in any of the problematic areas that you mention. I say unfortunately because I very much wanted to play a role in all aspects of this system, in order to ensure the correct outcome. During the design and analysis of the system my client enthusiastically promised a period of field testing that would allow us to monitor performance and behavior against analysis. Unfortunately this never materialized. I have never been asked to participate in correcting any problems with performance and to this date I have never been to the site. During start-up my client called once from the site because they could not align the belt coming out of the head end belt turn-over. Basically they had laterally jogged the belt line. I talked them through that and corrected the problem. There you have it, my total involvement in the field start-up.

Larry, I am very proud of our analysis work and the design recommendations that we made on this project. I regret that we did not have control of the outcome. To this day I had hoped that my client or his customer (the end user) would call on us to provide the design and field services that would have ensured the successful performance of this system.

If you have contact with that end user I encourage you to advise them of our offer to make the system right.

I would also be very intereted in obtaining the reports that you mention on this installation.

Joe Dos Santos ■