Regolith Melters

Just about everything manufactured or built in Moon Town starts with melting regolith. If it wasn’t imported, it was once regolith. As the town has grown, ever more giant stations were built to do nothing but melt regolith all day, and keep it molten all night. This is the first draft of the melters facility. Earlier in the town’s timeline, there were a variety of individual reactors of different kinds that melted their regolith feedstock in different ways. Now as much melting as possible is done at this main facility. Then it is taken for processing into metals, glasses, pure crystals of a number of elements or compounds, cast stone, and ceramics.

The town is 4.5 degrees south of the moon’s equator. This allows parabolic mirrors to track the sun on one axis, east to west, with no practical loss of efficiency. There is simply a wide enough gap between the south edge of each mirror and all other objects to account for sun bouncing at a small angle. The towers holding the mirrors and their equipment in place are made of lunar glass rods and cable made of spun lunar fiberglass. The mirrors have counterweights so they rotate easily around the heat pipe running through their focal line. 

Parabolic mirrors, insulated tanks, radiators, and Stirling engines
Melter complex overview, showing all mirrors, central storage silos, radiators, and Stirling engines

Moon Town produces both quartz and sapphire in industrial quantities, including single pieces of huge size. That is what is currently posited to be the main material of both the pipes and the mirror surfaces. Several layers of silver foil inside and aluminum foil on the exterior surround the external pipes. Sodium is the proposed heat carrying medium. 

View along the sapphire heat pipe

The central silos receive the heat transferred from 4 sets of mirrors. The materials available for the tank and the thermal mass and insulation layers that surround it include such things as bricks made from slag (left over from molten electrolysis reactors, fluidized bed reactors using hydrogen, and Schubert dust roasters), ceramic coatings such as calcia and magnesia, quartz, sapphire, aluminum, iron, and titanium. Under the insulating sheet metal cap is a work space and the tank roof, which is split into segments. Each segment had a lid sitting on a thick frame, and embedded in that lid are the heat exchanger and the pipes that descend from it into the molten mix. The central part of the tank has a set of pumps for all the pipes, and equipment to collect and condense the vapors that rise from the molten mix. 

Overnight the contents of the tank may be largely emptied and taken to various factories and construction projects. After dawn, when it is being actively heated again, many loads of fresh regolith are brought in and emptied from the gangway into the the tank. 

One of 5 huge silos holding molten regolith

The current configuration includes two Stirling engines for each silo and an accompanying radiator. Originally this complex was thought of in part as a power generation facility. It was thought the Stirling engines could be used to cool the tank walls, keep a crust of solid regolith against them that protected them. At night much of the power extracted during the day while doing this could be returned to keep the tank contents molten.  This idea may not be valid and this can be removed.

Stirling engines and a radiator, fine tuning silo temperature

Are you working on this model? – Please reference guidelines regarding materials, facilities, energy sources, tools, transport, and all else to do with the capabilities of Moon Town on the Designing and Building page