Metal Melting

TL;DR

Purpose: Receiving and preparing Al and Fe melts for casting

Source: MHD input at 1500°C from regolith processing

Equipment: Tundish with two stoppers

Throughput: 42 t Al + 11 t Fe-Mn steel/day

Overview

Metal melting is the first stage of factory element production. Molten metals (Al and Fe) arrive from regolith processing via MHD channels and are distributed to casting lines.

Process Diagram

flowchart TD
    subgraph EXTERNAL["OUTSIDE DOME"]
        DIST["Distillation<br/>Al 1500°C"]
        MRE["[MRE](../../reference/technology-readiness.qmd#mre-electrolysis)<br/>Fe-Mn 1500°C"]
    end

    subgraph ENTRY["DOME ENTRY"]
        MHD_AL["MHD Channel Al<br/>42 t/day"]
        MHD_FE["MHD Channel Fe-Mn<br/>11 t/day"]
    end

    subgraph BUFFER["BUFFER ZONE"]
        TUNDISH["Tundish<br/>2-3 t buffer"]
        VALVE_AL["Stopper Al"]
        VALVE_FE["Stopper Fe"]
    end

    subgraph OUTPUT["OUTPUT TO CASTING"]
        MNLZ_AL["→ CCM-Al"]
        MNLZ_FE["→ CCM-Fe"]
    end

    DIST --> MHD_AL
    MRE --> MHD_FE
    MHD_AL --> TUNDISH
    MHD_FE --> TUNDISH
    TUNDISH --> VALVE_AL
    TUNDISH --> VALVE_FE
    VALVE_AL --> MNLZ_AL
    VALVE_FE --> MNLZ_FE

    style EXTERNAL fill:#f0e68c
    style ENTRY fill:#fff3cd
    style BUFFER fill:#d4edda
    style OUTPUT fill:#cce5ff

MHD Melt Input

Magnetohydrodynamic channel is a method of transporting liquid metal WITHOUT contact with the pipe.

Parameter	Value
Principle	Electromagnetic levitation of metal
Temperature	1500°C (above Tm of Al 660°C and ferrosilicon ~1400°C)
Channel material	MgO-based ceramics (local production)
Insulation	Vacuum gap around channel
Heat losses	~2% (compensated by induction heating)

MHD advantages: - No metal contact with walls → no contamination - Works in vacuum (outside dome) - No mechanical pumps (magnetic field only)

More details: Regolith Processing

Tundish

Buffer vessel for separating aluminum and iron flows.

Parameter	Value
Volume	2-3 tons (30-60 minute buffer)
Body material	SiC ceramics (silicon carbide)
Lining	MgO refractory (local production)
Temperature	1500-1600°C
Cooling	NaK radiators around body

Two Stoppers (Gates)

The tundish has two independent stoppers for flow control:

Stopper	Metal	Flow Rate	CCM
Stopper 1	Aluminum	42 t/day	CCM-Al
Stopper 2	Fe-Mn steel	11 t/day	CCM-Fe

Operating principle: - Stopper closed → melt stays in tundish - Stopper open → melt flows to CCM - Control: automatic (level sensors in CCM)

Quality Control

Parameter	Control	Action on Deviation
Temperature	Pyrometers (±10°C)	Induction heating
Tundish level	Laser sensors	MHD flow adjustment
Metal purity	Optical spectrometer	Batch rejection

Automation: Tundish control system operates without operators — all parameters are regulated automatically.

Power Consumption

Component	Power	Purpose
MHD channels	50 kW × 2	Flow maintenance
Tundish induction heating	100 kW	Heat loss compensation
NaK cooling	20 kW	Coolant pumps
Automation	5 kW	Sensors, control
TOTAL	~225 kW

Material Balance

Daily flow:

Metal	Input (MHD)	Output (CCM)	Losses
Aluminum (Al)	42 t/day	41.5 t/day	1.2% (slag)
Fe-Mn steel	11 t/day	10.85 t/day	1.4% (slag)

Slag: Periodically skimmed and returned to MRE furnace for reprocessing.