Originally Posted by lukazi

Hello everyone,

I work in iron ore industry and one of the biggest problems we have, with a heavy impact on production, are chute blockages. They cause massive amount of delays. The way we deal with this at the moment is simply by opening chute doors and cleaning them manually. We require very high water pressure and often a lot of time to clean only one chute, due to sticky ore and heavy bulldup.

Is anyone aware of any automatic cleaning technology?

Added by Adminstirator as an example only:

Conveyor Design Software

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You can invest in slick sheet material that will prevent the iron ore from sticking. It is time consuming to to install but it works.

lzaharis

www.superslide.com ■

Originally Posted by lukazi

Thanks for your reply. That sounds like an excellent idea. I'm just a bit suspicious how the canons would cover such a large area inside the chute and still have very high pressure.

Would you have any link to this solution?

Good dau Lukazi,

We are the designers and developers of the WEBA Chute Systems and Solution. We agree that the design plays an important role. We have been developing a system using aircannons and other equipment to deal with sticky material. Please contact us directly for more information. You can email our CEO Werner Baller at wernerb@webachute.com ■

If the material sticks to the chute walls an air cannon is not an efficient cleaning method. Material is still stuck on the walls just waiting for the next chance to block the show. If an air cannon is useful it usually implies that there would be no blockage if the chute had been designed better. Very often the trouble with chutes lies in the quest for capacity at the expense of flow reliability. Most people ignore the fact that a blocked chute has no useful capacity other than overtime for the crew:..( half of the original thread confirms this). Until this is recognised there will still be air cannons and very good luck to them.

A not really recent thread concerned blocked chutes in permafrost conditions. One solution was to leave the outlet side open so that frozen material could be hacked out downstream. With a lot less hacking the principle could be applied to sticky material: or not?

In my pet topic of vehicles for bulk there are many walking floor applications coming on the scene. Could they be worth trying? ■

A common problem is that the reliable performance of chutes is crucial to efficient production yet they frequently receive scant detail design attention because they are considered simple items of low technology, where the eye can see a clear flow path. Their low capital cost to manufacture does not appear to warrant high design costs or the conduction of tests to measure the adhesion and friction properties on different contact materials. TUNRA has done much work on chute design to address blockage problems and wear and could be a useful contact. Some simple features, such as radius corners, are often not included. Sticky materials love the high surface are of square corners as a base to build on and can be quite tenacious to dislodge. Connections for high pressure water injection under potential blocking points may be useful if water can be tolerated, otherwise small air cannons could be effective for local regions. If the blockages are so disruptive to production you may consider redesigning the transfer point to include a clog resisting screw to keep the product moving. ■

Originally Posted by lukazi

..... mining companies have invested hundreds of millions of dollars in pursuit for a perfect chute, .......

I agree with most of this reply except the bit quoted above. The fact remains that chutes are seen as a simple box and as such they are not prioritised for research and development. Certainly not to the extent of hundreds of millions of dollars.

Flushing with water is tricky for the process metallurgist who has to mill the stuff later down the line. Sometimes its good and sometimes it isn't. That suggests that the material handling process was not correctly examined in the first place. If flushing was OK them why wasn't hydraulic conveying used in the first place? If the milling charge will not tolerate more water then the mill delivery system was clearly wrong. We accept that chutes will block but we still use them. Nickel mining in Australia improved the situation by primary ore treatment which enabled hydraulic conveying. It's probably been done elsewhere. When ore transport is undertaken the engineering takes run-of-mine to the plant in belt conveyors simply because it is perceived cheaper than alternatives. It definitely isn't the perfect way: but it is cheap...and nasty. The problem is not chute design it is a problem of plant layout and equipment selection by chemists masquerading as engineers.

If hundreds of millions of dollars had gone down the sewer then surely somebody should/would have seen the folly of sticky ores in chutes long ago. Whichever way you look at it: blame the accountants. ■

Before the Indonesians imposed their 'local content' restrictions on mineral ores it was common practice for the Chinese, and some others (French lesserly), to ship sticky, very sticky, laterite nickel ore to homebase. The only wetting involved was climatic. Topsoil was stripped; dumped aside in the forest and the ore was lightered aboard in Weda Bay, Halmahera. In some form of poetic justice, Hukum Karma, is the Asian phrase, several ships went down due to slip planes developing en voyage. Two mishaps are well recorded.

Shouldn't there be some legislation to protect sailors and the sea? What fool pays for unknown water content in his cargo anyway, coal exports apart? In the days when I was active I often proposed dewatering screening before the mast and nowadays I don't have to care: but there it is! Another can of worms. ■

The IMO says fines are not prone to liquefaction. Prone is another way of saying "what can happen will happen". Obviously there wasn't a proper Chinese translation.

Even so you are carting run-of-mine with larger lumps so fines are not the only cargo.

Rules are meant to be broken. When I took my ADR, hazardous goods, I was obliged to point out to the examiner that bulk coal was spontaneously combustible. He quoted absurd situations to compare baled straw and a single lump of coal. Some regulations say that heavy oil is not combustible but fail to explain how it changes into fuel. Many regulations are deficient by choice and even vaguer in application. Dewatering screens are cheap and effective means to limit moisture content and when an effective remedy is available it should be incorporated. Then there should be no objection to wetting at will.

The downtime caused by a sunken ship might even be more expensive than a blocked chute: with or without IMO backup and depending on the insurance situation of an ageing ship of course.

My reasons for mentioning clowns were that the ship is paid for tonnage; the clown has to dewater somewhere otherwise he wouldn't be asking for discount and the exporter is seriously reducing his cash flow and water recovery. Oft times in Western Australia the process water costs more than the iron ore...unless brine is used. Once again it enters the accountants court, bless 'em. ■