Xref: utzoo sci.astro:13864 sci.space:31801
Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!caen!ox.com!emory!wa4mei!ke4zv!gary
From: gary@ke4zv.UUCP (Gary Coffman)
Newsgroups: sci.astro,sci.space
Subject: Re: Platinum-group metal concentrations in earth-crossing objects
Keywords: gold
Message-ID: <2982@ke4zv.UUCP>
Date: 13 Jun 91 10:54:13 GMT
References: <sehari.676666308@du248-12.cc.iastate.edu> <5248@dirac.physics.purdue.edu> <1991Jun12.073415.12543@sequent.com>
Reply-To: gary@ke4zv.UUCP (Gary Coffman)
Followup-To: sci.astro
Organization: Gannett Technologies Group
Lines: 68

In article <1991Jun12.073415.12543@sequent.com> szabo@sequent.com writes:
>
>Back to platinum: we have a total of 55 ppm platinum group, about 5 
>times better than the best Earth ore.  This still wouldn't be that 
>good, given the high costs of launching mining equipment, except 
>that there exists a process which, taking advantage of the large 
>amounts of solar-thermal power available in space, could make 
>extracting the platinum economical.

Seems the only solar-thermal power you need is enough to boil water (100C).
We can get that much solar-thermal on the surface of the Earth. That kind
of low level process heat, boiling water temperatures, is available from
a multitude of sources here on Earth cheaper than going to space to find
it.

>First, we should find grains with the above concentrations or better
>in a high-metal regolith (a task for space exploration).  We
>extract the metal grains with a magnetic rake.  Next, we process

After first crushing the ore. Seriously big crusher. 999,945 parts
per million waste. Lots of maintenance and replacement parts.

>the metal regolith with the gaseous carbonyl process, as follows:
> 
>First phase: 
>
>Treat the regolith with CO at c. 5 atm pressure, 100 degrees 
>C.  This forms a vapor of gaseous carbonyl compounds. 
>Nickel and iron are selectively deposited in pure metallic form
>by lowering the pressure and/or increasing the temperature.  
>The CO is released and recycled. The residue has a Pt-group 
>concentration of 5,000 ppm, and Ga/Ge/As at 15,000 to 20,000 ppm.

Very big heavy pressure vessel made of non-reactive material. Lots of
CO, tankage, pumps, etc. Heavy maintenance and replacement parts.
Makeup CO.

>Second phase: 
>
>Treat the residue with moist CO at 100 atm near 100 degrees C.
>This deposits out cobalt.  What is left is largely Pt group
>and Ga/Ge/As, and is worth $20,000 per kg at today's prices.
>The water and CO are again recycled.

Big super heavy pressure vessel. More CO and water, tanks, pumps, etc.
More maintenance and replacement parts. Make up CO and water. Moving
masses of matter in and out of the high pressure chamber to vaccum 
will suffer high CO and water losses.

>This technique, called the gaseous carbonyl process, is currently
>used at the Sudbury mine in Ontario, primarily to extract the nickel,
>and secondarily to extract the c. 5 ppm platinum.  By some accounts
>the Sudbury ore is actually the remains of an impacted asteroid, 
>but I won't get into _that_ broohaha.  :-)
>
>If we want to get the pure elements additional processing is
>required.
>
>Which brings us to the billion dollar question: how soon will we have
>sufficient knowledge (through exploration) and technology (through 
>research and prototyping) to be able to undertake this projects for
>less than $10 billion?

Without dirt cheap heavy lift and regular on-site maintenance and replenishment
capability, never. Without a station and it's support systems, never. Without
men on-site, never.

Gary