SR06 Rare Resources Flashcards
Types of Rare resources
- SWIP (Solar wind implanted particles)–>
- REE
- PGM
Sulfur
Rare? resources
Resources with low in-situ abundance (trace elements)
Abundance of swip
More on far-side due to tail of magnetosphere of earth
Most abundant elements in Solar winds
Most abundant in solar wind:
1.
H
2. He
3. C, N, O
Lunar SWIP inventory
No element with abundance >125 ppm, except sulphur
Important to note:
1. None of the SWIP is an abundant resource
2. None of the SWIP can be mined independently
(other mined SWIP need to be processed, too)
3. Abundance most likely is higher than stated
(more on far side and at greater depth)
4. Larger uncertainty for H due to terrestrial contamination
SWIP Implantation
- Implantation depths < 1 micrometer
- Most concentrated in the fines (high surface/volume ratio)
- Abundance correlates with soil maturity
He/Ne- TiO2 correlation
- He and Ne contents are much higher in Ilmenite than other minerals
- Because most TiO2 on the Moon is Ilmenite, He/Ne correlates with TiO2
- No such correlation for H, C, N, and heavy noble gases
Sulfur occurence
Sulfur
* High Ti-mare basalts have 0.16–0.27 wt% (terrestrial basalts rarely have >0.15 wt%)
* Primarily available as sulfide in troilite, larger deposits may exist
* Sulfur melts around 113–119 °C
* Extraction of sulfur from Apollo samples (released as SO2 or H2S):
12–30% at 750°C / 50–70% at 950°C / 85–95% at 1100°C
Sulfur uses and limitations
Use as concrete: Needs no water, corrosion-resistant, best poured at 125–140 °C, attains most of its final strength within hours
but: thermal stability is a concern
Use as sealant: In a mixture with elastomers
but: currently technically too complex
Use as fluid: SO2 for refrigerant systems, turbines, heat pipes, material transport, etc.
but: toxic in large quantities
Other uses are thinkable that exploit the electrical and biochemical properties of sulfur, even as rocket fuel
Carbon sources
- Solar wind (approx. 200 ppm saturation level)
- Volatisation during impact/agglutination
- Outgassing and release of CO/CO2 due to thermal metamorphism
3He abundance on the Moon
- 3He abundance on the Moon can be up to 15 ppb in sunlit areas and 50 ppb in permanent shadow
- The global average is 4.2 ppb (Fegley and Swindle, 1993)
- Total 3He content of the Moon was estimated with:
- 8.4e8 ± 6.9e8 kg (0.84 Mton) (Fegley and Swindle, 1993)
- 7.15e8 kg (0.715 Mton) (Taylor, 1994)
- 6.6e8 kg (0.66 Mton) (Jin, 2012)
- High abundances might be found in high-Ti basalts
at Mare Tranquillitatis and Oceanus Procellarum, with a
combined estimated mass of 0.2 Mton; underlying models
also account for depth distribution (first 3 m)
D–T fusion cycle
D–T fusion cycle: D + T → n (14.1 MeV) + 4He (3.5 MeV)
-> 80% of the energy released as neutrons, which can cause damage to reactor wall materials and induce
substantial levels of long-lived radioactivity in the structural components
D–3He fusion cycle
D–3He fusion cycle: D + 3He → p (14.7 MeV) + 4He (3.7 MeV)
-> releases far fewer neutrons (few %) than the D–T reaction
-> energy output can be converted to electricity at high efficiencies
-> Lower radioactivity, lower risk, fewer radioactive waste
-> But: requires higher plasma temperature and more stringent confinement conditions
3He challenges for ISRU
Consider for the discussion:
* Additional power needed for mining
* Amount of material that needs to be processed/excavated/heated…
* Collecting 3He simply as byproduct from other mining operations and extractions
* Risk of radioactive waste (D–3He, some neutrons)
* Challenges for the reactor in a lunar environment (thermal/impacts… underground?)
* Export infrastructure to Earth for terrestrial use (additional emissions vs. 100% clean energy)
* …
REE
Rare Earth Elements (aka Rare Earth Metals)
* A group of 17 metallic elements with similar physical and chemical properties (3rd group + lanthanides)
* Tend to occur together in the same mineral deposits but in very dispersed form
* The diversity of REE-bearing deposits makes extraction/processing techniques variable and complex
REE uses
used in permanent magnets,
e.g. for electric vehicles, digital technologies or wind
generators
PGM
Platinum Group Metals (aka Platinum Group Elements)
* Six noble precious metallic elements with similar physical and chemical properties
* Tend to occur together in the same mineral deposits
PGM uses
Uses of PGM
* Highly resistant to wear and tarnish, chemical attack, excellent high-temperature characteristics, high
mechanical strength, good ductility, and stable electrical properties
* One in four products surrounding us contains PGM or has been produced with the use of PGM
* Found in catalysts, anticancer drugs, medical implants, dentistry, electronics, jewellery, etc.
Problem with REE/PGM
mineral criticality and technology-critical metals
Distribution of world‘s REE reserves
-> Geopolitical issues
-> Volatile prices
REE Extraterrestrial sources
- The majority of lunar samples contain REE-bearing phases as minor or trace components (KREEP)
- Lunar REE abundances are low compared to terrestrial ores
- Chondrites also contain REE, but again the abundances are lower than on Earth
- Chondrites could rather be mined for PGM
Asteroids 101
The asteroids’ compositional differences are related to how far from the Sun they
formed. Some experienced high temperatures after they formed and partly melted,
with iron sinking to the center and forcing basaltic (volcanic) lava to the surface.
* The C-type (chondrite) asteroids are most common. They consist of clay and
silicate rocks, and are dark in appearance. They are among the most ancient
objects in the solar system.
* The S-type (“stony”) asteroids are made up of silicate materials and nickel-iron.
* The M-type asteroids are metallic (nickel-iron).
Are C-type asteroids worth mining?
- Not for REE
(all abundances significantly less than on Earth) - But for PGM and Cr/Ni
