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Cargo ships that sink when their cargo suddenly liquefies (theconversation.com)
281 points by YeGoblynQueenne 9 months ago | hide | past | web | favorite | 115 comments

If you want a quick primer on buoyancy physics and ship design, Marine Insight has a good writeup:


As the article mentioned, wave action will cause the center of gravity (CG) of the liquid to shift, and with it the overall ship's CG. This puts the ship in a new stable equilibrium heeled over to that side. If the compartment isn't dewatered, this process can repeat until the 'stable' equilibrium includes upper decks taking on sea water. CG shifts up, righting arm becomes flipping arm, hull experiences stress beyond tolerances, breaches kill remaining buoyancy, and down she goes.

By the way, the easiest way to tell if a ship is in danger of hitting critical (aka neutral aka very very bad) stablility, watch how long it takes to rock from side to side. A ship that has an excessively long roll period and appears to be hanging to one or both sides can in serious danger.

Segmenting the cargo hold? Not necessarily all the way to the bottom, just enough of disrupt superficial sloshing?

I wonder if sheets of a cloth-like material could be used in loading similar to Mechanically Stabilized Earth

Practical Engineering has a great video on this simple but pervasive technology. https://www.youtube.com/watch?v=0olpSN6_TCc

If it's really behaving like a liquid, then you wouldn't want those gaps.

Loading the cargo into close-packed hexagonal storage silos would prevent it from shifting too much during transport, and even if it did liquify, it wouldn't slide too far out of balance.

You can fill/empty these of granular cargo using large diameter hoses.

You could also create one or two special storage bins that can be rotated to an arbitrary degree to help right the ship if it gets into trouble. They're carrying ridiculous amounts of ballast, why not put some of it to use as a counter-weight?

You dont need silos, just baffles. If the cargo doesn't slosh over to one side or another, then it cant solidify in such a position either.

Lower a vertical baffle grid into the hold with a crane. Secure it to the hull. Fill the hold with bulk cargo. Ship it. Raise the baffle grid with a crane. Unload the bulk cargo. Repeat from start.

You just need open tops and open bottoms in the grid. Open at the top so the cargo can fill the cells between baffles, and open at the bottom so the grid can be raised out of the cargo.

You'd probably have to vibrate the cargo and/or the baffle to get it to settle in, which could be tricky, but it's not impossible. Not a bad approach.

The hatch would need to be the same size as the hold, as well.

The baffle grid would need to be the same size as the deck opening. Those are rather large on bulkers, AFAIK. Permanent baffles with open sides can be installed in the sides of the holds. I think those parts probably have sloped sides to follow the bowl shaped cross-section of the ship anyway.

Because that's more expensive to implement/load/unload then dumping the whole heap in an open bay and insuring the hell out of it

This is a very old problem and solutions and knowledge has been available for over 20 years.

But I think the main problem is cost: not waiting for the rain to clear, not making time to install temporary bulk heads, and so on.

Edit. for example this article from 1998: http://www.gard.no/web/updates/content/52980/shifting-solid-...

That was my first thought too. Shipping liquids is a solved problem. You baffle containers to limit shifting and slapping. Doing the same for dry bulk seems like a no-brainer? There must be a consideration I'm entirely missing.

Normalcy bias. Its the oldest killer in the world.

Dry goods are supposed to be dry... soak wheat in fresh or salt water for a couple weeks you may as well dump it in the ocean, its rotted (its brewing, technically). The problem is SOME dry goods (bauxite, etc) are not the driest to begin with and of course the usual leaks and accidents.

The crew knows exactly what to do if there's a storm or the engine stops or a fire breaks out, but dry goods are supposed to be dry, so when they aren't, the blind spot kills the crew. You could give up training for storms or fires to run liquefaction drills, but that'll kill more people on long term average, because storms are more common than weird cargo issues. Even if labor money is no object, brains can only hold so much at one time.

So, this thread is actually addressed in the article. The article is not about discovering this phenomena, but about why it's still happening. Just a bit of a poor title that doesn't quite summarise what the article's actually about.

From the article:

Yet despite our understanding of this phenomenon, and the guidelines in place to prevent it occurring, it is still causing ships to sink and taking their crew with them.


The International Maritime Organisation have codes governing how much moisture is allowed in solid bulk cargo in order to prevent liquefaction. So why does it still happen?

The technical answer is that the existing guidance on stowing and shipping solid bulk cargoes is too simplistic. Liquefaction potential depends not just on how much moisture is in a bulk cargo but also other material characteristics, such as the particle size distribution, the ratio of the volume of solid particles to water and the relative density of the cargo, as well as the method of loading and the motions of the vessel during the voyage.

> You could give up training for storms or fires to run liquefaction drills,

Why do you have to do one or the other? ¿Por que no los dos?

Time. Training time is limited, nonfungible, and rivalrous. Adding material at one end sacrifices it at another, ssomething has to give: other parts of the curriculum, or prodctive time.

There's a similar problem, at scale, for civilisation as a whole. Given a lifespan of 85 years, and working span of 65, we spend 18 years on basic education. The managing/professional class need another 4-6 for undergraduate education, plus 2 for professional degrees, 6-12 for engineering and some medical specialties. We're drawing people into the workforce in their late 20s, early 30s, and hope to get 30-40 years contribution.

At the same time, technology, or practices, or standards, obsolete much that information in 10-15 years.

How many times do you, and can you, effectively retrain someone before their prior knowledge is an inescapable impediment, and there's no useful retraining benefit regardless. Confound further with the distiction between explicit (book-learned) and taxit (experiential) knowwledge. The first can be effectvely taught through technical reproduction: lectures, books, A/V, computer-distributed or aaided materials. The latter requires small-ratio master-student raatios for transmission. Skills lacking sufficient masters (or those effective at training) die out.


>> There must be a consideration I'm entirely missing.

Just the standard business "reason" - cost.

I am sure that is the main part of it, but there is probably a certain amount of complacency and ignorance in play.

I would guess that, for the vast majority of bulk-cargo voyages, there is no noticeable shifting, making it it easy to assume that it is not a risk. A captain who has never experienced the problem is probably less likely to stand up to the shipper (and the ship owner's management, which is an issue in itself) over whether a cargo is fit to ship.

The article linked by pasta shows that the problem has been recognized and regulated, for some cargoes, a while back (e.g. grain in 1982), but the lesson has not been generalized.

In case of a grain liquefaction emergency, you can simply toss in a few tribbles, and its consistency will quickly change from granular to fuzzy.

Also, the rock eating monsters of Janus VI work well against bauxite liquefaction, and M-113 salt vampire creatures are highly effective against salt liquefaction (but unfortunately there is only one surviving creature).

It's not quite the same problem - when the ship rocks, if a true liquid shifts to one side through the baffles, it'll shift back to center when the ship recovers.

If a sometimes liquid substance shifts to the side, it may become a solid again and stick there, and then it can happen again and keep building up until the ship can no longer recover.

I imagine introducing baffles would significantly complicate unloading, as right now the procedure is basically to lower bulldozers and other heavy machinery into the hold and use it to keep the cargo in few piles that can be easily grabbed by a crane.

Liquid transport doesn't have the same problem since you can just pump the cargo out.

It's costly and unnecessary if you can ensure that the cargo behaves as a solid. There's also the issue that once behaving as a liquid, it can then seize to do that, and remain in a slumped state.

Baffles and other physical elements don't impede pumping a fluid as much as they do unloading solids I'd guess.

I find it sad that the article speaks of "new technology" and proposes lots of complex (thus error-prone and not cheap) solutions, when the very simple solution has been known for a very very long time:


Keep the cargo in containers which are always full or nearly so. If it doesn't have room to slosh around or shift, it won't.

The added bonus is that it costs less per volume to ship, if the vessel is always full.

And/or load less of the stuff onto a ship. I'm surprised that wasn't suggested either.

I believe it was mentioned, albeit somewhat indirectly:

> Commercial agendas also play a role. For example, pressure to load vessels quickly leads to more hard loading even though it risks raising the water pressure in the cargoes. And pressure to deliver the same tonnage of cargo as was loaded may discourage the crew of the vessel draining cargoes during the voyage.

If crews don't want to dump some cargo to restore balance, they surely don't plan to to ship less cargo.

So ship shakes. The aluminum ore, bauxite, turns to liquid due to pressure increasing (or friction decreasing). Ore moves to one side of the ship. Pressure drops as shaking subsides. Ship becomes side heavy and lists and sinks. This is as weird as things can get with reality.

It doesn’t really “turn to liquid” but really starts behaving according to fluid dynamics.

Nothing melts or freezes. More to the point, the motion of the macroscopic objects (rocks, sand, dust, powder) being dumped in by conveyor belt create huge piles that slump in odd ways, as piles form, and then settle oddly.

To illustrate what you mean: The Abelian Sandpile Model, aka the Bak–Tang–Wiesenfeld model, is a dynamical system displaying self-organized criticality, that suggests you can't predict the behavior of adding one more grain of sand to a pile, because it might have very little effect, or it could cascade into a huge landslide.



>In physics, self-organized criticality (SOC) is a property of dynamical systems that have a critical point as an attractor. Their macroscopic behaviour thus displays the spatial and/or temporal scale-invariance characteristic of the critical point of a phase transition, but without the need to tune control parameters to a precise value, because the system, effectively, tunes itself as it evolves towards criticality.

>The concept was put forward by Per Bak, Chao Tang and Kurt Wiesenfeld ("BTW") in a paper published in 1987 in Physical Review Letters, and is considered to be one of the mechanisms by which complexity arises in nature. Its concepts have been enthusiastically applied across fields as diverse as geophysics, physical cosmology, evolutionary biology and ecology, bio-inspired computing and optimization (mathematics), economics, quantum gravity, sociology, solar physics, plasma physics, neurobiology and others.

>SOC is typically observed in slowly driven non-equilibrium systems with extended degrees of freedom and a high level of nonlinearity. Many individual examples have been identified since BTW's original paper, but to date there is no known set of general characteristics that guarantee a system will display SOC.

They refer to "the relatively new solid bulk cargo bauxite". Surely bauxite shipping is as old as the advent of electrolysis (Hall–Héroult + Bayer processes)?

I think you guys are parsing that sentence as “relatively new cargo, bauxite”. At the top of the article they define “solid bulk cargo” as a shipping jargon term, for a fine granulated material. This seems like a dangerous misnomer to me...

I’m assuming that means that historically, the refiner owner the pulverizing equipment and shipped in bauxite rock or gravel as raw material. When you hear of liquefaction in terms of earthquake damage, they are always talking about saturation of fine materials. Saturated gravel doesn’t behave as badly as saturated sand or clay.

I assumed the word new in that usage referred to it being newly taken from the ground, thus having more unpredictable moisture content. Bauxite is basically just dirt.

This video talks of shipping bauxite from South America to the US in 1941: https://www.youtube.com/watch?v=EK4dEEoKNiE

Similarly, Wikipedia claims bulk carriers have been around since 1850: https://en.wikipedia.org/wiki/Bulk_carrier

Doesn't sound all that new.

Not over long distances. It's still ore, after all. Not something you want to ship further than you have to.

Could it help by creating a vaccum, at least lower the pressure? If the container is airtight and can withstand the forces the pressure would keep it solid?

This is called free surface effect with liquids and as has been mentioned by other posts is a common and known problem with liquids. Free surface effect is a core component of vessel stability and is part of maritime stability education.

So here is a random observation for some enterprising grad student or postdoc; is electric charge responsible for liquefaction on packaged solids?

Triboelectric charging is not well understood yet, it happens in dust storms and volcanic eruptions where charge is transferred to particulates from the air. As charge increases this results in "dry lightning" or other discharges.

If you wanted a research topic, I think you could look into the hypothesis of whether or not a powdered material could be charged to exhibit liquid properties.

Note that the way these bulk solids are loaded on to ships it typically by conveyor belt where they then drop through the air (charging opportunity) and then dropped into a conductive container (the hull of a steel ship).

If someone has looked into this already I'd love to read the paper on it.

Liquefaction has nothing to do with triboelectricity.

The article has a pretty good description of how liquefaction proceeds: higher pressure -> water present in material reduces contact between solid particles -> material friction reduced -> material behaves like a fluid. If you want more, find a book on basic rheology. I'm certain there are civil engineering textbooks that contain the material.

Further, it does not stand to reason that charged materials would suddenly acquire fluid properties. Solid materials are quite capable of sustaining charge without changing their bulk properties. Prior to significant change, local voltages would exceed the breakdown voltage and the charge would be neutralized.

You are offering to do the experiment? The physics is pretty straight forward, particles which share the same charge will repel each other, this will hold them apart and allow them to 'slide past' each other just as diamagnetic material float along a magnetic field.

So, this is kind of similar to the whole corn-starch-and-water non-newtonian solid kind of problem, right? A little different, because this isn’t entirely about mixtures, aqueous solutions or colloidal suspensions, but more about the fundamental behavior of large quantities of particulate solid mass.

The title could differentiate between being a total loss at sea, versus sinking while docked in a harbor, at least in terms of statistics and death. Also, how is there not one picture of a listing ship in this article?

Totally fascinating read. What's amazing to me is what the insurance costs and payouts happening must be. I imagine the losses are staggering.

Equally amazing is that catastrophic failures like these are almost invisible to the consumer. The economy just keeps humming along and we don’t even register a major cargo ship sinking because the shelves are always full.

No doubt. I was really surprised when I started following sites like https://gcaptain.com/ how many cargo accidents take place per year that practically no one hears about.

The losses are most prevalent on ULBCs, resulting in the biggest ships of all capsizing.

Insurers work with ship regulators and ship owners to prevent this, as not only does it mean they've lost the ship and cargo, but picking up a new ULBC is not a quick process.

What's a ULBC?

ULBC: Ultra Large Bulk Carrier

Ultra large bulk carrier

The article says there are around 10 solid cargo ships lost per year. There are around 10,000 such ships in use. Such a ship costs ~$20M new. Cargo shipments take around 7 weeks door to door, so assuming that also roughly covers dock time, and ships run to near capacity timewise, on avg a ship makes ~7 trips per year.

So, out of around 70K trips, 10 result in ship loss. It's entirely possible that the cost to reduce that loss rate against all reasons for loss and across all 10K ships and 70K journeys is far greater than simply allowing 10 failures.

Those losses are also likely insured against with the cost spread across the 70K trips. The insurance against them is likely therefore cheap.

The insurance cost assuming a 10% overhead is something like $3,200 per trip and that is just the portion of insurance for this one kind of event. Thus eliminating 90% of these events would save around $20k per ship of insurance cost per ship per year.

While that isn't a huge amount compared to say their capital costs it is a non-trivial amount of money.

Note that your $20M ignores the cost of the cargo as well as the cost of the lives lost. The later can tend to get much higher if fixes aren't found for problems that are known since letting ships sink to save some money is negligence assuming a fix can be reasonably found.

>since letting ships sink to save some money is negligence assuming a fix can be reasonably found

I'd assume there are smart people in the shipping industry that have spent a lifetime on such issues. I suspect there is not some "reasonably found" solution that will help.

It may be as simple as surprise severe weather events sink many of those lost - and the cost to protect such a large fleet from rare events is extremely costly.

Paying $3200/trip for insurance against ship loss of this kind is peanuts for protecting a $20M item that generates millions annually in revenue.

And the insurance on the goods (and this $3200) is simply passed on to those paying to ship goods.

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.

The 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).

I 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.

Can 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.

But, 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.

> 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.

Yanking 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.

Agreed. I read this and thought, "Oh my God, why not use baffles?"

Yeah, but the original state of the material was solid. You can't compartmentalize a solid unless you break it.

Bauxite 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.

Read 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.

It’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.

The 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...?

The 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.

So why do they mention draining?

Or large parts of SF during an earthquake.

It was solid, but granular - the article gives the example of crushed ore and mineral sands - so it's already broken up.

What 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.

That 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.

Friction 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.

This 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

But 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?

Even 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.

Why don't they treat this cargo under the assumption that it is a liquid and transport it accordingly (e.g. in large barrels)? I mean this question genuinely as someone with little knowledge of logistics.

Because bulk transport, even including the cost of occasional sinkings due to liquefaction, is cheaper?

See also Glückauf, the first tanker designed to transport oil directly in the hold rather than in barrels. https://en.m.wikipedia.org/wiki/Gl%c3%bcckauf_(1886)

I suppose in addition to the measures described in the article, bulk ships could adopt cargo holds divided into more subcompartments (including longitudinally, to reduce risk of capsizing) , similar to tankers.

Try putting 200,000 tons of coal into barrels, transport it, and then unbarrel it at the other end. The extra cost and time would be massive.

What about just compartmentalizing the ship's cargo space?

They are also compartmentalised. Bulkers tend to have four or five large tanks to hold stuff in.

I imagine they don't do that so they can carry more than just these bulk loads. Carrying bauxite in one direction and scrap iron the other, for example.

If I recall, this problem was used in "The Martian" by Andy Weir, when one of the rockets carrying supplies failed. At high pressures, some of the cargo liquified and the rocket exploded due to shifting weight distribution. It may have been another book...

Yep (spoilers), that was what happened to the rocket that was supposed to bring supplies to Watney so that he could survive until the next scheduled mission (prompting the crew currently returning to earth to "turn around")

10 ships a year + 10 years = 100. Wow.

I’m guessing insurance going to be even more expensive now unless 10 ships a year out of however many ships out there is minimal.

This has been a problem for decades and is already priced into the insurance. It's also not a big part of the world fleet.

The Wikipedia article on bulk carriers states the fleet size as: "9,570 vessels over 500 GT".


Something to consider when people suggest nuclear marine propulsion.

This reminds me of the meme that goes "when I was a kid, I thought quicksand was going to be a much bigger problem than it is."

Pardon my ignorance, but what would happen if you just divided the hold into smaller compartments? That way sloshing would only move things slightly to one side.

It would cost a bunch of money but go part of the way towards fixing the problem.

But if you're going to spend the money, maybe you could entirely fix the problem. You'd have to run the numbers!

It's already divided into smaller compartments, through the containers themselves.

Think of a ship transporting prisoners in their own little cells. Then think of all the prisoners working together to throw their weight against the walls of the cells at just the right moment in an effort to sink the ship.

The prisoners would only have enough of an effect to make the guards a little nervous. The ore sloshing around in the containers weighs tons and tons, though, enough to actually sink the ship.

but the article suggests that permanent accumulation in one side, rather than transient force, is the cause.

There's a very similar phenomenon as a plot point in Neal Stephenson's The Baroque Cycle, involving waves in medieval Japan

I don't remember it in The Baroque Cycle but didn't The Martian have a part where the high calorie care package being sent to Mars liquified during take off and caused the rocket to explode?

Yes, in The Martian in-flight vibrations cause a cube of food rations on a supply rocket to liquify, build up harmonic oscillations, and finally rip apart the rocket.

I have read The Baroque Cycle, but it is huge and my memory is imperfect. Mind reminding me of the details of this plot point, so I don't searching through the whole un-indexed stack of bricks on my bookcase? :)

When they are leaving Japan after trading the damascus steel ingots for quicksilver, the Japanese fill all the quicksilver bottles to a level that will cause it to slosh along with the same frequency, causing harmonic resonance to sink the ship. Before leaving they open all of the bottles and transfer the quicksilver so that they are filled to the top and can't slosh. This is from memory and may not be completely accurate.

Not only tuned to a common frequency but tuned to match a predominant wave pattern in the mouth of the harbor they were departing.

I had a hard time reading this part, as the puzzle placement seemed so forced and nonsensical to the plot. What did the Japanese gain from this stunt if it worked? A sunken ship in their harbor leaking mercury from hundreds of smashed jars...?

I think the idea was to sink the ship by capsizing it, then bring up the intact bottles with free divers. Any mercury leaks would immediately sink, and would probably stay inside the hold of the ship long enough to recover it. If it escaped, it would run into the nearest local minimum on the harbor bottom. If rock bottom, just scoop it up into fresh bottles. If sandy bottom, scoop up the sand with it and separate it on the surface.

So they keep the wootz payment, they recover the cargo, and they don't lose reputation by just murdering the crew of a merchant vessel outright. If the merchants capsize instead, that's a shame, and a result of poor seamanship, and they'll just go ahead and pretend to be sad during the salvage operation.

I thought I had heard at one point that Industrial Age Japan was responsible for some substantial fraction of mercury contamination of the ocean but I can’t find a citation for that.

What I did find is Minamata disease, which is a particular set of symptoms from severe mercury poisoning, documented in a town in a bay on the western end of Japan.

Maybe Neal was making some sort of nod to that?

Minor point; Root recognises the hazard and adjusts the flasks such that the levels differ, thereby disrupting the harmonics.

The loading and pseudo-solidification can cause residual internal stresses that change the dynamic response so that a small signal input gets a big change as a result.

I'd imagine that the exact values are not monitored, so that what is written as "in the hold" and what is actually there are subject to natural variation, which can be asymmetric, and thus theory and practice are not the same thing.

If seawater gets into the mix, it will have more water.

There are thermal phase changes in the liquefication. It can behave very differently at 10 deg C warmer than one expects from 0 deg C warmer.

Over a relatively long trip, with agitation, the mean particle size is going to change. Big particles are going to break into smaller particles. This is going to change the liquefication physics.

Awesome. My boy and I were talking about liquefaction and phase solids last night when he was showing me how the sea salt behaves as a solid in the shaker (humid here) until he bangs on thr glass.

Check out the physics of ketchup.


YouTube science educator Mark Rober's "Liquid Sand Hot Tub - Fluidized air bed"

They mention that solids are stored in a sort of liquid suspension. Why is that? I feel like a solid, airtight box (like a shipping ocntainer) 100% full of sand wouldn't doo too much.

Ever moved a large pile of sand that's been stored outside? Once you get a foot or so into it, there's going to be some moisture. It's not going to be much by weight, but it's there. Of course, it's going to vary depending upon environmental factors (humidity, temperature how recently it rained, etc). That contributes partially to the liquefaction.

Interesting read. I thought all along that materials change state due to temperature changes. Time to track down my teachers and show them this article.

You learn something new everyday

Although unlikely that liquefaction caused this wreck, my mind went first to the SS Edmund Fitzgerald.

There appear to be many factors that went into that sinking: huge storm, 30-35 ft waves, possible rogue waves even larger; improperly secured hatch covers, no water-tight bulkheads(!!); regulations that allowed overloading and decreased freeboard, etc, etc.[0]


I don't understand the point of "two-phase" materials. Why would you add water to ore?

First up, we're not talking about a soup here, this isn't like it's a litre of water for every kilo of ore, it's just that it's enough to allow the solids to move without the friction they'd incur if entirely dry.

Ore starts out as rock buried in the ground. So, you're going to need to get that out of there. While you could do that with a bloke and a pickaxe I'm sure lots of the processes actually involved add water, even if not terribly much.

Also, this stuff isn't expensive, it's basically just slightly valuable dirt, so if it's stored somewhere they're not going to be keeping it in water-tight containers, it'll be in an open truck, or an open freight car somewhere, getting rained on.

Now, shipping dirty water across the ocean is pointless and costs money, so it's not as though they're going to add more water just for fun, but if the contracts involved don't specify that it has to be less than so-and-so much water in the cargo, then it's nobody's job to ensure it isn't damp.

Ah! Thanks. I imagined an intentional mix for some reason.

I was expecting a Sperm whale's reference somewhere ;-)

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