Particle seperation by density using acceleration

[kthakore]

For a research assginment I was asked to research 0-g mining methods, and a new method suggested @ this site URL=http://www.tsgc.utexas.edu/floatn/1999/99_fall/teams/charleston.html]here I was wondering how this would work? and how Newton's law can be applied to it

 

[kthakore]

sorry the website is http://www.tsgc.utexas.edu/floatn/1999/99_fall/teams/charleston.html

 

[Diane_]

Well, I would quibble with the use of the word "density" unless they're also screening for size. Remember Newton's Second Law - the acceleration of an object is directly proportional to the net force on the object and inversely proportional to the mass. They propose providing a constant force for each particle - I haven't looked, but I would imagine it'll involve charging the particles and using an electric or magnetic field. In that case, the acceleration will depend entirely on the mass of the particle. Larger mass, lower acceleration. By measuring the acceleration of the particles, you could determine the mass. If you knew the size of the particles, then you could determine their density fairly easily.

All of this sounds rather like the way a mass spectrometer works. Look here:

http://www.jeol.com/ms/docs/whatisms.html

and here:

http://en.wikipedia.org/wiki/Mass_spectrometer

Briefly, a mass spectrometer takes the sample and turns it into an ionized gas. Remember - ions are charged. It then accelerates that gas using electric fields and dumps the resulting beam into a magnetic field. A charged particle moving through a magnetic field experiences a force perpendicular to the direction of its motion, which causes the particle to curve. The radius of curvature will be determined (all other things being equal) by the mass of the particle. You set up a detector plate somewhere where the particles will strike it after they've curved and you determine the mass of the particles by where they hit the detector.

 

[kthakore]

Since the asteroids one would wish to mine would be metallic in nature, the miners would break it up into same peices, use magnetic fields to accelerate them. Am I getting it right so far? I understand it would separate the steel from unwanted material such as rock, but how would the collect it?