3.1.1 Glass Fiber Line

Overview

Parameter Value
Input Silicates (~5% of non-magnetic fraction)
Output Glass fiber
Throughput ~30 t/day
Energy consumption Solar furnace (thermal)
Location Under the dome

Back to overview

Purpose of the Line

Part of the silicate stream (~5%) goes to glass fiber production directly, bypassing MRE electrolysis.

Why a separate line:

  • Fiber production requires silicates in their original form (oxides SiO2, CaO, Al2O3)
  • In MRE, oxides are decomposed by electrolysis into metals + O2
  • If everything were electrolyzed, no silicates would remain for fiber production

flowchart LR
    subgraph INPUT["NON-MAGNETIC FRACTION"]
        NM[/"Silicates<br/>564 t/day"/]
    end

    NM --> |"~5%"| GF["Glass fiber line<br/>(solar furnace)"]
    NM --> |"~95%"| MRE["MRE electrolysis"]

    GF --> FIBER[/"Glass fiber<br/>~30 t/day"/]
    MRE --> METAL[/"Metals + O2"/]

    style GF fill:#b8e0d2
    style MRE fill:#e8a8d4

Silicate Composition (Feedstock)

Mercury regolith silicates already contain the required composition for glass fiber, similar to industrial E-glass:

Oxide Fraction Role in Glass
SiO2 ~45% Glass former
Al2O3 ~15% Strength, chemical resistance
CaO ~10% Flux (lowers melting point)
MgO ~10% Strength
FeO ~5% Impurity (gives greenish tint)

Note: On Earth, E-glass contains boron (B2O3) to lower the melting temperature. Mercury has no boron, so we melt at a higher temperature (~1400C), which is not a problem for a solar furnace.

Process Diagram

flowchart TD
    subgraph MELTING["MELTING"]
        SIL[/"Silicates<br/>~30 t/day"/] --> SF["Small solar furnace<br/>1400C"]
        SF --> MELT["Molten glass"]
    end

    subgraph FIBERIZATION["FIBERIZATION"]
        MELT --> FILT["Al₂O₃ bushings<br/>(ceramic)"]
        FILT --> FIBER["Fiber 5-13 um"]
        FIBER --> DRUM["Winding drum"]
    end

    subgraph PRODUCT["PRODUCT"]
        DRUM --> BOBBIN[/"Glass fiber<br/>bobbins"/]
    end

    style MELTING fill:#fff3cd
    style FIBERIZATION fill:#d4edda
    style PRODUCT fill:#cce5ff

Stage Description Temperature
Melting Silicates melt in solar furnace 1400C
Fiberization Melt is forced through Al₂O₃ ceramic bushings 1200C
Drawing Fiber of 5-13 um diameter is drawn by drum -
Winding Fiber is collected onto bobbins -

Equipment

Component Function Materials
Small solar furnace Silicate melting Al mirrors, MgO crucible (local)
Ceramic bushings Fiber drawing Al₂O₃ (local)
Winding drum Bobbin collection Fe frame, Al drum

Ceramic Bushings (Al₂O₃) - Local Production

Parameter Value
Material Al₂O₃ (corundum)
Operating temperature up to 1800°C (glass fiber 1200-1400°C ✓)
Service life 3-5 years
Source Regolith processing (Al 7% + O₂ 45%)

Why ceramics: On Earth, platinum (Pt-Rh) is traditionally used. Scientific research has shown that Al₂O₃ ceramic bushings produce fibers of comparable quality (ScienceDirect, 1981). Al₂O₃ is produced from local feedstock (Al 7%, O₂ 45% of regolith per MESSENGER).

Design

Element Material Purpose
Crucible MgO ceramics (local) Silicate melting
Bushings Al₂O₃ ceramics (local) Fiber forming
Cooling Air (dome atmosphere) Fiber cooling

Glass Fiber Applications

Product Criticality Purpose Alternative
Cable insulation Critical All factory wiring Ceramic beads (difficult)
Winding insulation Critical All motors, transformers Al2O3 ceramics (brittle)
Dome fabric High Al-membrane reinforcement, new factories Metal only (heavier)
Thermal insulation Medium Equipment protection MgO ceramics, vacuum
Filters Low Gas purification In vacuum, dust settles by itself

Conclusion: Glass fiber is a critical material. Without it, factory electrics (cables, motors) and expansion (new domes) are impossible. The line is fully localized — Al₂O₃ ceramic bushings are produced from local feedstock (Al 7%, O₂ 45% of regolith).

References

See Also