Xref: utzoo sci.astro:13836 sci.space:31764 sci.engr:1386 Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!sequent!muncher.sequent.com!szabo From: szabo@sequent.com Newsgroups: sci.astro,sci.space,sci.engr Subject: Re: Platinum-group metal concentrations in earth-crossing objects Keywords: gold Message-ID: <1991Jun16.024747.28781@sequent.com> Date: 16 Jun 91 02:47:47 GMT References: <5248@dirac.physics.purdue.edu> <1991Jun12.073415.12543@sequent.com> <1991Jun16.000359.10311@world.std.com> Sender: news@sequent.com (News on Muncher) Organization: Sequent Computer Systems, Inc. Lines: 113 In article <1991Jun16.000359.10311@world.std.com> webber@world.std.com (Robert D Webber) writes: [Excellent article re: asteroid mining] >In the absence of a container the composition of the GaAs crystal comes >out wrong... This is an interesting statement; why does this occur? >>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 >>the metal regolith with the gaseous carbonyl process, as follows: > >You will need to break the hunk of rock down in size quite a bit, first... I agree that breaking down the solid metal is difficult. I don't propose to do that for the first mining projects. I am looking for metal regolith (dust and flakes) that is ready to melt. This is known to exist in very small percentages scattered on the Lunar surface, and probably exists in much higher concentrations, perhaps up to >90%, on the surface of metallic asteroids. Alternatively, brittle chondrites contain up to 30% metal flakes and this can be crushed and raked with a magnet to get nearly pure metal regolith. Exploration can make the mining operations much simpler by pointing out the most easily processed material. >So how much does it cost to get the carbon monoxide and water up there >in the first place? Good question. The answer is that comets, carbonaceous chondrite asteroids, and possibly comet fragments in meteor showers contain carbon compounds including carbon monoxide, and also contain abundant water. The ice can be captured using solar thermal engines and the ice itself as reaction mass. The ice-mining operation will have to pay for itself in terms of reaction mass, shielding, heat sinks, and fuel manufactured from the ice materials and used in Earth orbit. I call this "ice bootstrapping" since ice as reaction mass can be used to lift more equipment to catch more chunks of ice, etc. until the cost of fuel, heat sinks, and shielding in Earth orbit is very low. As you point out rock and metal processing is quite non-trivial. In comparison, however, ice mining requires little more than a mirror, bag, and simple distillery. After the ice bootstrapping takes place, it will be much easier to lift heavy mining equipment out to the asteroids, or alternatively bring raw asteroid regolith to Earth orbit and process it there. The ice also provides the water and carbon monoxide needed for the carbonyl process. Volatile mining will likely be the first use of extraterrestrial materials, but it cannot occur until we have explored the earth-crossing asteroids and meteor showers sufficiently to find good sources of ice, or, failing that, the highest concentrations of water of hydration and carbon in chondrites. >Incidentally, you will need a fair bit of material for the >carbonyl process fixtures as well. The units I saw on a tour of the >Inco facilities in Sudbury were pretty massive, though I'll grant you >that a space facility can be less concerned about accidental carbonyl >releases than an earth-based one. This is a rather underated aspect of space industry. In the long run, it can replace many Earthside industries that really should not be conducted in the middle of an ecosystem. In the short run, the ability to work outside the ecosystem can make some processes significantly cheaper. I am not sure to what extent the carbonyl process is an example; can any readers shed more light on this? >>If we want to get the pure elements additional processing is >>required. > >No kidding?! :-) At this point the impure mixture of platinum-group elements, gallium, arsenic, and other stuff is already worth $20,000/kg. The rest of the processing can be done on Earth. If we want to use any of these in the pure form in orbit, we need the "additional processing." >I've often wondered whether any of the people who figure that metallurgical >operations in space would be simple have ever visited an earthside >metals extraction plant. I share your impatience. In the space community there is an underestimation of mining engineering across the spectrum of mining operations. Many "Manned Mars Mission" scenarios, for example, propose extracting fuel from extraterrestrial regolith and assume that the mining engineering is going to be trivial without detailed analysis or, for that matter, even bothering to ask a mining engineer. Mining equipment is itself difficult; mining equipment in vacuum and microgravity will take much engineering and trial and error before we get it right. On the other hand, if we use the abundant thermal energy, microgravity, and vacuum to full advantage, some of the processes become much easier. (Some become much harder, so we don't use those). That is my other pet peeve on this subject. Merely transfering Earth mining techniques into space is stupidity. We need to take full advantage of the new environment. Much work has to be done to determine which processes gain the most advantage, what new processes are made possible, and how much can be done with the least mass of equipment. The actual mines will bear very little outward resemblence to their Earthside counterparts. At $3.4 billion/year for just the platinum-group elements, billions more for space-manufactured semiconductors, alloys, and other products, and potentially tens of billions per year for solar power satellites, there is quite a bit of incentive for that work to get done. -- Nick Szabo szabo@sequent.com Embrace Change... Keep the Values... Hold Dear the Laughter... These views are my own, and do not represent any organization.