A review of options for processing extraterrestrial materials was dominated by industrial materials scientist who tried to identify which processes utilizing space materials could be implemented in the near term. The most practical process seem to us to be the extraction of lunar oxygen and the extraction of metals and ceramics from the residues of the reduction process. The growth of space activity will be accompanied by increased demand for liquid oxygen for each round trip to the Moon. The oxygen and the intermediary product water will be needed for the life support at the base. The reduced metals and ceramics may be considered byproducts or may develop into primary products. Some of the same processes would be directly applicable to recovery of products from asteroids. We also discussed other processes for directly utilizing asteroid metals. Some of the topics covered include beneficiation and oxygen extraction methods, metallurgy, and extraterrestrial cement

Agosto, William N.

English

NASA Technical Reports Server

N93 - 1 8 86'j
6-'//-9/
PART 2--Beneficiation and Extraction
of Nonterrestrial Materials
William N. Agosto
The group that reviewed options for
processing nonterrestrial materials
was dominated by industrial
materials scientists who tried to
identify which processes utilizing
space materials could be
implemented in the near term.
The most practical process seemed
to us to be the extraction of lunar
oxygen and the extraction of metals
and ceramics from the residues of
the reduction process. The
growth of space activity will be
accompanied by increased demand
for liquid oxygen for rocket
propellant. In particular, any lunar
base activity will require tens of
tons of oxygen for each round trip
to the Moon. And, of course, the
oxygen and the intermediary
product water will be needed for
life support at the base. The
reduced metals and ceramics may
be considered byproducts or may
develop into primary products.
Some of the same processes
would be directly applicable to
recovery of products from
asteroids. We also discussed other
processes for directly utilizing
asteroid metals.
Beneficlation and Oxygen
Extraction Methods
Reduction of lunar ilmenite with
hydrogen imported from Earth was
judged to be an oxygen extraction
option that could be implemented in
the near term. Ilmenite, an iron
and titanium oxide, is the most
abundant oxide in the samples that
have been brought back from the
Moon-
Working for Lockheed Corporation
at the Johnson Space Center,
I reported the successful
concentration of ilmenite in an
Apollo 11 soil sample, using an
electrostatic separator based on a
commercial design and operated
both in nitrogen and in a vacuum.
This was the first research reported
on the industrial behavior of actual
lunar material. Additional research
is needed to determine the
characteristics of a system that
could operate on the Moon.
A process not requiring
beneficiation, because it extracts
oxygen from the predominant
silicates, was probably the first
process considered for extraction
of oxygen from lunar materials.
The carbothermal process was
developed by Sanders Rosenberg
and colleagues at Aerojet-General
Corporation in the mid-1960s,
before we had been to the Moon.
They assumed that ordinary rock-
forming minerals, such as olivine
and pyroxene, would be abundant,
an assumption that proved to be
mostly correct. Rosenberg and his
colleagues performed a series of
experiments demonstrating actual
oxygen extraction from simulated
lunar materials. In addition, they
designed an oxygen production
plant and did a parametric analysis
146
https://ntrs.nasa.gov/search.jsp?R=19930007697 2020-03-17T09:35:52+00:00Z
of mass, power, and cost. David
McKay has combined several of
their papers from that period and
updated the cost analysis to 1989
dollars. This combined paper
presents the basic concepts of the
carbothermal process, gives the
results of some of the laboratory
experiments, and includes the
design concept for a lunar oxygen
plant. The paper is interesting
both because of its historical value
in presenting a lunar oxygen plant
designed before Apollo 11 and
also because the basic concept is
still viable today as a candidate
oxygen plant for a lunar outpost in
the early 21st century.
In a review of proposed lunar
oxygen production processes,
including carbothermal reduction
and electrolysis of basatts,
Christian W. Knudsen and Michael
A. Gibson, of Carbotek, Inc.
(Houston), have concluded that
hydrogen reduction of ilmenite is
the simplest process proposed.
Products of the reaction are iron,
titanium dioxide, and water; oxygen
is then extracted from the product
water by electrolysis. Both batch
and continuous-flow fluidized-bed
processes for the reaction have
been described. Although the
preliminary results of bench-level
tests on the batch process
conducted by Richard J. Williams
at JSC seemed promising, further
engineering work by Knudsen and
Gibson indicates to them that only
a continuous process is
practicable on a large scale.
Knudsen and Gibson also
considered hot pressing of the
metallic iron and titanium dioxide
residues of the reaction into
cermet parts and bricks, as
outlined by Agosto (1981).
Russell O. Colson and Larry A.
Haskin discuss the direct
electrolysis of molten lunar
material to produce Oxygen. In
the magma electrolysis process,
iron, silicon, or iron-silicon alloys
are produced at the cathode and
oxygen is produced at the anode.
Potential byproducts include
ceramics (spinels) and cast-rock
products such as bars, beams,
and sheets. Colson and Haskin
argue that, compared to most
other proposed processes, this
process requires less energy per
unit of oxygen and has the
advantage of being relatively
simple. Technology challenges
include finding container and
electrode materials that will
withstand the corrosiveness of
molten silicates. The work of a
number of years has determined
some of the fundamental
properties of melt conductivity and
some of the factors affecting the
efficiency of oxygen production.
Solar furnace pyrolysis of lunar
basalts in vacuum, as proposed
by Elbert A. King and me (1983),
is considered another highly
promising process for
nonterrestrial oxygen production.
It does not require reagents
imported from Earth. King (1982)
147
demonstrated the process on Earth
using terrestrial basalts and
samples of the Murchison meteorite
heated to approximately 3000°C in
a furnace with a solar mirror
2 meters in diameter. Residues
of metallic iron and oxides of
aluminum, calcium, and titanium
indicated the evolution of oxygen
and volatile oxides of other
elements. A bench-level research
program is required to characterize,
quantify, separate, and capture the
oxygen and other volatiles liberated
by the process. Residues of the
process include metals (iron),
semimetals (silicon), ceramics
(AI-Ca-Ti oxides), and feedstocks
rich in aluminum oxide for
aluminum electrolysis.
Wolfgang H. Steurer, of the Jet
Propulsion Laboratory, considered
two vapor-phase processes:
(1) the volatilization of oxygen by
vacuum pyrolysis of oxides and
(2) electrostatic separation of
metals from high-temperature
plasmas of nonterrestrial materials.
The high temperatures and
reactivities of such processes
suggest that the technology will
be difficult to develop. However,
such processes may prove to be
effective.
Metallurgy
David F. Bowersox, of Los Alamos
National Laboratory, has described
a novel anhydrous chloride
process, used in the nuclear
industry to recover plutonium,
which could be adapted to extract
iron and titanium from nonterrestrial
basalts and ilmenite. All reagents
and products of the process are
recycled and, because it is
waterless, the system is one-tenth
the size of an aqueous system with
the same metal output. It has the
disadvantage of being a metal
extraction process that does not
directly yield oxygen or water, and
it requires chloride salts, which are
rare or absent on the Moon.
However, as a successful operating
anhydrous system that recycles all
reagents and products, it merits
serious consideration for
nonterrestrial application.
Karl R. Johansson has reviewed
the literature and found several
bioprocesses for the beneficiation
of lunar and asteroidal materials by
the action of microorganisms.
Notably, the extraction of metals by
(1) oxidation-reduction reactions,
(2) acid leaching, (3) pH alteration,
(4) organic complexing, and
(5) cellular accumulation of metals
due to the action of bacteria on
minerals. All these bioprocesses
would require stringent radiation
and temperature controls in closed
aqueous environments having
elements in which the Moon is
deficient, like carbon, nitrogen, and
hydrogen. However, Karl says that
the process of microbe-enhanced
vat leaching, which is used
terrestrially to concentrate copper
ores, might be applicable to
extracting common lunar metals
148
likeironandmanganesefrom
lunarrocksandsoils. Inaddition,
bioaccumulationf metalsby
microbialcellsmightbeused
to concentraterare(andoften
toxic)elementslikecopper,lead,
mercury,cadmium,andsilverand
removethemfrombiological
systemsontheMoon. Inhispaper
Karlalsomentionsmetalreduction
byanaerobicbacteria,theuptake
of silicatesbydiatoms,anda
tantalizingclaimin theRussian
literatureof "silicatebacteria"
thatconcentratealuminum
oxidebyfreeingsilicatesfrom
aluminosilicateores. However,
humansettlementsandearlylunar
industrialoperationswouldprobably
haveto bewellestablishedbefore
controlledbioprocessingsystems
couldbesetup innonterrestrial
locations.
Ifaqueousprocessingwereto
provepracticable,thenleachingof
usefulelementsfromlunarand
asteroidalmaterialsby inorganic
acidslikehydrofluoricacid,without
theintroductionof microorganisms,
mightwellbea moredirectand
productivemethodof extracting
mostofthemajorlunarelements
(oxygen,silicon,aluminum,iron,
magnesium,titanium)aswellas
manyoftheminorones(sodium,
potassium,manganese,chromium,
phosphorus).SeeCriswell(1980).
MetallurgistConstanceF.Acton
hascriticallyreviewedproposed
processesformetalproduction,
usingtheharshcriterionof
terrestrialcommercialviability.
Ironin lunarsoilmaybethemost
easilyobtainedmetalresourceon
theMoonthroughthelowenergy
extractiontechniquesof magnetics
andelectrostatics.Itsphysical
extractionpresentsmany
challenges,but it is likelyto beone
of theeasierobjectivesfornear-
termlunarresourcedevelopment(Agosto1981).Actonpointsout
theneedforhardthermodynamic
andkineticdataonallthereactions
andthenecessityfor long-term
bench-leveltestingandpilotplant
facilitationof themostpromising
processes.Sheoutlinesthe
extensive ffortrequiredto provea
commercialmetallurgyprocess
throughthermodynamicandkinetic
chemicalevaluation,bench-level
feasibilitystudies,andpilotplant
operations.Herassessments,
basedon terrestrialexperience,of
longleadtimes(20-50years)and
highR&Dexpenditures(hundreds
ofmillionsof dollars)to develop
systemsarechallengesto the
designerof lunarmaterials
processingtechnology.However,
the longleadtimespresume
developmentof processes
competitivewiththoseof terrestrial
suppliers.Thatassumptiondoes
notapplyto theinitialprovisionof
productsfromlunarsourcesfor use
inorbit.
JohnLewis,of theUniversityof
Arizona,presentedto ourgroup
informationonthegaseous
carbonylprocess.Carbon
monoxideisreactedwithmetalat
149
low temperature to purify it or
separate one metal from another.
With a relatively low energy input,
lunar metallic iron might be purified
or trace elements, particularly
platinum group metals, could be
separated from asteroidal metal.
Although considerable terrestrial
experience is in hand, adaptation
to the space environment remains
a challenge for future investigation.
Nonterrestrial Cements
T. D. Lin, of Construction
Technology Laboratories (CTL),
the research arm of the Portland
Cement Association, proposed
to our workshop group the
manufacture of cement from lunar
oxides and in his paper proposes
concrete as a building material for a
space station and a lunar base.
The major constituents of common
types of cement occur in lunar
highland anorthosites and
lunar mare basalts. The high
compressive strength and the mass
of lunar-derived concrete would
make it an effective shield against
radiation and micrometeorite
impacts and thus a candidate
material for orbital and lunar
structures. Concrete is fireproof,
lends itself to modular construction,
and can be reinforced with Moon-
derived metals and fiberglass to
improve its tensional and flexural
strength. Lunar cement would also
be useful as mortar to assemble
building blocks of other materials,
whether imported or nonterrestrial.
Common concrete mixtures are
about 10 percent water by weight,
but drier formulations can be
developed and the water can be
recovered as the concrete dries. In
any case, typical concretes, which
consist of 2/3 to 3/4 aggregate
materials bonded by cement,
retain only 5 percent water
when thoroughly dried, which
corresponds to only a few tenths of
a percent of Earth-derived mass in
the form of hydrogen (Cullingford,
Keller, and Higgins 1982). Suitable
lunar aggregates could readily be
obtained by crushing and grading
rocks from the lunar surface.
I have proposed a method for
concentrating lime (CaO)in lunar
materials to Portland cement
formula levels, using phosphates
that might be lunar derived. A
similar process was proposed by
Ellis M. Gartner, of CTL, using
terrestrial phosphate. Construction
Technology Labs received
40 grams of lunar soil from the
Johnson Space Center in 1986;
from it CTL fabricated a lunar
mortar sample, which was tested
and proved usable. NASA is
interested and the project has
attracted favorable attention
from the press. The apparent
widespread interest in cement as a
lunar product and public recognition
of it may generate substantial
support for its development.
150
The consensus of the group 2.
working on beneficiation and
extraction of nonterrestrial materials
was that there is a near-term need
for bench-level data on lunar and
meteoritic materials processing,
such as (1) beneficiation of
industrially valuable minerals
in lunar soils and disaggregated
lunar rocks and meteorites;
(2) oxygen and metal extraction
processes, like carbothermal
reduction of silicates, hydrogen 3.
reduction of ilmenite, magma
electrolysis, vacuum pyrolysis,
and anhydrous chloride reduction,
using actual nonterrestrial samples;
and (3) formulation of cementitious
compounds from lunar oxides
and aggregates. The above
research should be conducted
under conditions approximating,
as closely as practicable, the
expected operating environment.
This work is necessary to make a
credible case for nonterrestrial 4.
materials utilization to the materials
science community.
Recommendations
1, Support for a thorough bench-
level hardware investigation
and demonstration of the
beneficiation, primarily by
electrostatic and magnetic
means, of lunar soils and
crushed rocks for minerals
like ilmenite, anorthite, and
pyroxenes, and valuable minor
phases like metal, chromite, and
phosphate.
,
Support for bench-level
research and development of
the carbothermal process,
including additional testing to
determine optimum pressure
and temperature conditions for
feedstocks of various
compositions, such as
simulated mare basalt and
concentrates of ilmenite or
pyroxene.
Support for a thorough
investigation of the
thermodynamics and kinetics
of hydrogen reduction of lunar
ilmenite, together with a bench-
level laboratory research
project to investigate the
workability of hardware designs
like those of Richard J.
Williams and Christian W.
Knudsen and Michael A.
Gibson.
Support for additional studies of
magma electrolysis, including
laboratory work on the basic
process, development of
innovative electrodes and
containers, and investigation of
the effects of feedstock of
different compositions. This
effort should also include
engineering evaluations and
plant design concepts.
Support for a thorough
investigation of the
thermodynamics and kinetics
of solar furnace vacuum
pyrolysis of nonterrestrial
materials. The effort should
\
151
.7.
,
,
include a bench-level research
project to characterize,
quantify, separate, and
capture oxygen and other
volatiles liberated by high-
temperature vacuum pyrolysis
of lunar and meteoritic
materials, as well as thorough
characterization and chemical
analysis of resulting
condensates and residues.
A literature search and
evaluation of the anhydrous
chloride process for plutonium
reclamation reported by
David F. Bowersox and its
applicability to production of
metals and ceramics from
nonterrestrial materials.
Support for bench-level
research on aqueous leaching
of nonterrestrial silicates
with inorganic acids like
hydrofluoric acid, as well as
beneficiation by bioprocesses
derived from the action of
microorganisms on
nonterrestrial minerals.
A study of the application of
the carbonyt process to the
purification and extraction of
lunar and asteroidal ferrous
metals.
Support for the development
of cement formulations from
lunar materials and cement
and concrete fabrication
processes adapted to lunar
and orbital manufacture and
applications.
References
Agosto, W. N., and E. A. King.
1983. In Situ Solar Furnace
Production of Oxygen, Metals and
Ceramics From Lunar Materials. In
Lunar & Planetary Sci. XIV, Special
Session Abstracts: Return to the
Moon (March t6) and Future Lunar
Program (March 17), pp. 1-2.
Houston: Lunar & Planetary Inst.
Agosto, William N. 1981.
Beneficiation and Powder
Metallurgical Processing of
Lunar Soil Metal. In Space
Manufacturing 4, Proc.
5th Princeton/AIAA Conf., ed. Jerry
Grey and Lawrence A. Hamdan,
365-370. New York: AIAA.
Criswell, David R. 1980.
Extraterrestrial Materials Processing
and Construction. Final Report on
Mod. No. 24 of NASA contract
NSR 09-051-001. Houston: Lunar
& Planetary Inst.
Cullingford, H. S.; M. D. Keller,
and R. W. Higgins. 1982.
Compressive Strength and
Outgassing Characteristics of
Concrete for Large Vacuum-
System Construction. J. Vac. Sci.
Technol. 20:1043-1047.
King, Elbert A. 1982. Refractory
Residues, Condensates and
Chondrules From Solar Furnace
Experiments. Proc. 13th Lunar &
Planetary Sci. Conf., Part 1. J.
Geophys. Res. 87 (suppl.): A429-
A434.
152


Beneficiation and extraction of nonterrestrial materials, part 2

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