In all geologic time, the responsibilities are on our generation ... including you ...

4.2.1 Magnetic Separation of Free Metals

As discussed in the section on asteroid resources, asteroids are rich in free nickel-iron metal granules. The Moon has trace but extractable quantities of these granules as well, left over from asteroid impacts and preserved on the waterless, rustless Moon.

Though there are big differences in concentration and size of granules between the two sources, the basic process is the same.

After grinding, the streams of material are put through magnetic fields to separate the nickel-iron metal granules from the silicate grains. Repeated cycling through the magnetic field gives highly pure bags of free nickel iron metal. One of several alternative ways is to drop a stream of material onto magnetic drums, as shown in the figure below. This method also shows an impact grinder discussed in the next paragraph. The silicates and weakly magnetic material deflect off the drum whereas the magnetic granules and material holding magnetic grains stick to the magnetic drum until the scrape off point.

An optional additional piece of equipment is an "impact grinder" or "centrifugal grinder" whereby a very rapidly spinning wheel accelerates the material down its spokes and flings it against an impact block. Any silicate impurities still attached to the free metal are shattered off. It's feasible to have drum speeds sufficient to flatten the metal granules by impact. A centrifugal grinder may be used after mechanical grinding and sieving, and before further magnetic separation. In fact, most of the shattered silicate will be small particles which could be sieved out.

Magnetic beneficiation can be used not only for separating pure nickel-iron metal granules, but also for minerals which have weak magnetic properties. This is done at Earth mines. In space, where gravity is lower and more sensitive processes are possible, magnetic beneficiation can play a significantly greater role.

The quick & dirty theory

There are minerals that are attracted, repulsed, and unaffected by magnetic fields, based on their "permeability" to magnetic fields. This is often illustrated by showing a picture of magnetic field lines and grains which attract lines by bending them into the grain (concentrating), grains which repel the lines, and grains which aren't affected. The degrees of magnetic permeability differ from mineral to mineral. Particles which concentrate the lines of force and become polarized and consequently attracted are called "paramagnetic". Those which disperse the lines are called "diamagnetic".

Based on magnetic behaviour, paramagnetic materials are sub-classified as ferro-magnetic and feebly magnetic.

Magnetic separators are classified as drum, pulley, disc, ring and belt separators. They are all based on the same principle, and all use a provision for feed to run into and through the magnetic field and various means for discharging separately the magnetic and nonmagnetic portions.

See also the PERMANENT section on electrostatic beneficiation, a similar process for separation of minerals based upon electrostatic, instead of magnetic, properties. > Manufacturing, Industry > Materials Processing > Magnetic Separation


PERMANENT needs a PHP / MySQL (actually, MariaDB) programmer. Are you a PHP / MySQL programmer interested in getting into space development as a career, or already working in space development? Or do you know somebody else who might be interested?

There is an ongoing process to update this website in 2019 with a target relaunch in 2020.
This website is actually very out of date. Much of the website text content was written in the 1980s to early 2000s, but that's a different matter. As regards PHP / MySQL, some offline databases go into the 2010s, as regards professional publications, engineers, companies, etc., and this is what we need programming help with. We are updating our databases on people, organizations, publications, and other things, for open source space development for all.

The current status is we have some working databases which we have been using internally for a long time for organizing professional publications, and to track people (authors, R&D people, other professionals, quality volunteers, journalists, etc.) and organizations. We want to put information online for the general public pending a security review of the programming code.

Step 1 is fixing some bugs in what we already have, the PHP code. It is functional, and been used a long time, but there are some bugs.
Step 2 will be improving the system. Some small improvements would help its usability.
Step 3 will be a security check for putting it online for the general public to be able to access and use, but with reasonable protection against hackers.
After Step 3, the main mission is accomplished, as regards PHP / MySQL, though of course we hope to keep people engaged and happy, and the sky's not the limit.

This is a volunteer, unpaid role at this point in time. A limited paid role would be considered on a tight budget, such as for at least bug fixing with some minor improvements, and/or a security review of our code before it goes online publicly. If you or one of your friends or associates may be interested, please send an email to spaceprogrammer at ... of course this domain.

Reasons to do something yourself:

  • It will help save life on our special planet -- be part of the solution in your generation.
  • It will create and secure a better future for your children and grandchildren.
  • It could be an interesting, cool, and a fun adventure for your life!

You can join us and volunteer to help out,

... or ...

If you're short on time, you can just donate:

The Permanent Space Development Foundation, Inc., is a 501(c)(3) nonprofit organization.
If you would like to make a quick donation to our humanistic cause,
then please click on one of the buttons below (which go to PayPal).

... or by cryptocurrency (which is NOT tax deductible), you can donate into any of these wallets:





... or ...

Suggest this website to other people and organizations.

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If you are interested in hiring our expertise, anywhere in the world, please contact us.
We have people in the USA and Thailand, and can travel or consult by internet.
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Many website artistic design elements by Sam Fraser, Copyright © 1999-2021, All Rights Reserved.

Except where specifically stated otherwise,
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