Ever seen the result of a paper clip getting vacuumed up by a Hoover? I’ve never yet seen it fail that the belt pulls the clip wire out and wraps it around the central stem that drives the belt – and then the wire chews up the belt in short order. (And will chew up the replacement in short order if you’re not checking carefully for the neat little spirally-wound ‘addition’ to the shaft…)
I went to Electrolux tank vacuums really early; in fact, I still have the first ‘family’ PL-1. It’s been through the factory reconditioning steps four times and still runs perfectly well.
It occurs to me that a good starting point would be the self-serve vacuums at my local car wash. Those things really suck; keep small pets and children clear.
The problem is not really whether you can build a vacuum that moves enough air to do the trick (there are limits, but once you have shakers and the right kind of heaters the issue can be managed). It’s how you get the load out of the car as quickly, cheaply, and ‘undamagedly’ as rotary or bottom dumping would do.
Cleaning out when changing loads – that’s another matter, and as noted a significant one.
In the manufacture of semiconductor devices, many steps are done under extremely low pressure, some on the order of microns of mercury. One evening, I asked one of the techs who maintained such equipment, “How’s High Vac?” His response: “It sucks.”
When you come upon a loaded grain train derailment - one of the first things you will see as wrecking operations are getting underway is vacuum truck(s) - unloading the derailed loads into other railcars or highway trucks to lighten the weight of the derailed cars. It is much easier to work with a 30 ton empty car than it is a 140 ton loaded one.
You mean the coal customer’s pulverizers were not happy when they found taconite pellets in their coal. Chert is a kind of flint iirc.
With typical luck this would have been hemitic taconite and not magnetic taconite; would the usual sort of tramp-iron separator before the pulverizer work on either one before the fun sounds started?
I wonder (don’t know for sure) about imparting static charges to all those particles bouncing down the vacuum pipes. I would hate to see a static discharge amongst all that coal dust.
Not enough energy in the spark discharge to light off the carbon, even with bituminous volatile content. Then you have to look at the dwell time of a particle in the system after it ‘lights off’, the radiant coupling to other particles to ignite them, and the amount of energy actually released if more than one of the particles catch fire “together” as they are blown through. But you also have to consider the very large volume of moving turbulent air at temperatures far below ignition; you might as well think of it as ‘blowing out’ any small sparks that might be initiated.
If it were very finely divided, like the result of some SRC processes (resembles copier toner) or the carbon black at Flixborough, THEN you might have some fun. Firelock76 might have some interesting toner ‘detonics’ stories if he has conducted some of the logical “experiments” his line of work might provide for…
The most practical thing they could do is vacuume coal dust out of the coal on conveyor belts coming from the coal mines and pump the coal dust into pressure-differential covered hoppers.
Loram makes a vac for ballast and such where tracks can’t be cleaned with an undercutter. they also built a couple on tracks for a railroad to suck out iron ore before the cars were loaded with coal for the trip back. So they exist but are slow compared to dumping cars.