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Fascinating read! Can this situation can be avoided if the loading bay has a cover/lid on top of the material? As long as the loading bay is 'full' (or the to
by LeonM 8y ago
Fascinating read!
Can this situation can be avoided if the loading bay has a cover/lid on top of the material?
As long as the loading bay is 'full' (or the top is movable to fit the cargo) the material won't be able to slosh around, thus preventing the situation described in the article.
- werdnapk 8y agoEven if a lid would work, I'd assume it would be too large and expensive to deal with. The lid would have to be rather heavy duty. As noted in the article, the solution needs to be cheap and relatively easy to deal with.
- chillydawg 8y agoThe usual solution, as with petrol tanks in cars and elsewhere, is to use baffles. It effectively turns one large tank into several smaller ones and stops the liquid from freely sloshing from one side to another. The sloshing causes problems non-linearly with size of tank, so reducing one tank into 4 or 8 has a huge impact on the risks of sloshing. The partitions/baffles are always vertical (although I expect aerospace baffles are a bit more fancy).
- MPSimmons 8y agoAgreed. I read this and thought, "Oh my God, why not use baffles?"
- amelius 8y agoYeah, but the original state of the material was solid. You can't compartmentalize a solid unless you break it.
- maffydub 8y agoIt was solid, but granular - the article gives the example of crushed ore and mineral sands - so it's already broken up.
- aunty_helen 8y agoBauxite is pretty much red Australian dirt. It will be carted as small pebbles or a powder. If it was large solid pieces it wouldn't turn to liquefaction.
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- winceschwab 8y agoIt’s not a true liquid, but rather solid dust mixed with trace amounts of water. Drier than mud, but powder and rock that can shift in a fluid-like way. It’s like an avalanche or rock slide.
- hfdgiutdryg 8y agoThe article mentions moisture several times, as well as draining moisture during the trip. It also explains liquefaction in terms of water acting on the solid, whereas I always thought it was just about granularity. From the article, it doesn't sound like it's about trace amounts of water at all. It sounds like water is somehow involved in the loading process...?
- Retric 8y agoThe liquid is simply acting as a lubricant. So, it takes a very small amount to make a large difference. Really it's less soggy than simply damp.
- hfdgiutdryg 8y agoSo why do they mention draining?
- NegativeLatency 8y agoOr large parts of SF during an earthquake.
- jsjohnst 8y agoRead the article again. Yes, it’s a solid, but a solid more similar to sand or dirt than to a mountain or solid block of metal.
- gnode 8y agoI imagine a problem with that solution is that most of the time, the solid isn't behaving as a liquid. The partitions / baffles may complicate unloading, as you can't just pipe the solid out; a conveyor belt is typically used.
- MPSimmons 8y agoCan we intentionally liquifact the solid into a liquid? Also, we can have articulated baffles that raise into place from below, cutting into the solid material. I think this is a solvable problem.
- VLM 8y agoBut, if the engineering and financial cost of "fixing" transport is higher than the cost of simply moving the bauxite processing plant to the bauxite instead of moving the bauxite to the plant... Murphys Law is someone will put an aluminum smelter pot on a nuclear powered ship, during a storm the molten cryolite will slosh out of the pot freezing onto one side of the ship, sinking the ship, and we're right back to where we started.
- gnode 8y ago> articulated baffles that raise into place from below From where below? My understanding is that the bottom of the tank is the hull. Although possibly you could put baffles in place, tip the grain, then crane them out for unloading.
- donarb 8y agoYanking the baffles out of the hold while the material is still there would be next to impossible. You have tons of weight pressing on them from all sides, not counting the weight of the baffle itself.
- quirkot 8y agoThis could be true only if the density of the material doesn't change. In this situation, though, it's the temporary compression of the cargo that causes the liquefaction
- LeonM 8y agoBut if it has nowhere to move to (no air pocket in the cargo bay) then it wouldn't matter in what state the material is, right?
- Steltek 8y agoWhat about an inflatable airbag that rests on top of the cargo? That could keep the cargo from shifting and would be very quick to setup at the end of loading the ship, as there would be no messing with plates or tie downs.
- LeonM 8y agoThat airbag would still allow the cargo underneath to shift. It's the same a the current situation (air), but with a bag around it ;-) I guess you need something solid, and fixed to the boat, so there is nowhere for the material to go.
- logfromblammo 8y agoFriction is not the same between a canvas layer and an air layer. As an experiment, fill a bowl with sand. Level the sand with a scree bar. Tilt it until you notice sand shifting, and note the angle of tilt. Now level the bowl and put an inflatable bag on top. Tilt until you notice sand shifting and note the angle. Further experiment: put a vacuum hose through the center of the bag, and suck air out of the bowl as the bag covers the top. Tilt again. If your bag can make a decent seal against the rim of the bowl, and you keep that vacuum pump running, you can almost flip the thing without shifting any sand.
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