| Comparing Production of Steel, Mg, Al and Ti by David A. Dietzler 2007 To make steel from iron bearing lunar silicates we will need to; 1) Extract the irony minerals with powerful magnets from mare soil or orange volcanic glass. 2) The glass must be ground finer and magnets used to extract the irony minerals in it that color it. The iron bearing mare regolith will be seived and the rocks and gravel ground up in jaw crushers, rod and ball mills, etc. We will make these machines from blister steel made from iron fines over the years. 3) The irony Moon dust will be filled into molds made by drilling holes into cast basalt blocks, pressed, and heated with microwaves until the particles sinter together to make ore lumps for the furnace. The same thing will be done to powders of MgO, CaO and CaAl2O4 for lumps of flux. This will take a lot of work but it is necessary. 4) Flux will be obtained by boiling and condensing MgO out of mare basaltic "soil" and CaO and CaAl2O4 by boiling anorthite. 5) The iron ores and flux are reduced with hot CO gas and liquid iron and slag come pouring out of the furnace. 6) Then we decarburize the iron in open hearth furnaces to make steel. 7) The slag must have traces of carbon removed because carbon is so rare on the Moon and so useful, therefore valuable and essential to lunar industry. This is done with hot oxygen in a ceramic fluidized bed. see; Lunar Carbon Supply After the lumps are prepared, and smelted in DRI furnaces, ingots of iron, or possibly high carbon steel, will be poured into sand molds or sent directly into open hearth furnaces. The slag will pour out into sand molds to make big slabs. These will be pulverized, crushed and ground in rod mills to make a cement powder along with some CaO perhaps and some CaSO4 and some highland regolith that has been heated up to 2000-2200 C. to make a preparation of 40% CaO 50% Al2O3 and 10% SiO2. Cement and concrete by mixing it with "sand" (regolith) and gravel will be the primary construction material in lunar lava tubes when we obtain sufficient water from volatiles mining, polar ice in shadowed craters, even subselene volcanic gas pockets. To extract magnesium we can just toss MgO powders from basalt roasting at over 1500 C. , flux powders and ground up FeSi from magma electrolysis or FeSi that was sprayed out of a nozzle when liquid to make a bunch of FeSi droplets, the finer the better probably, then toast it with solar energy and condense the magnesium that evaporates from the retort. Steel involves more work than magnesium, but magnesium is not strong enough for solar power satellites, mining machines or vehicles. Magnesium is highly reflective and soft and easy to roll into foil for reflectors of all sorts for solar furnaces. In the low gravity of the Moon it might have structural uses and it can alloy aluminum. Sounds like a lot just to have steel. But consider aluminum. 1) We must take anorthite obtained by magnetic and solar heat purification of highland soil. Then we must apply solar energy to boil away the alumina and leave CaO (flux). Alumina vapors will probably cool off and turn into powder with a brief liquid phase in the anorthite roasting furnaces. 2) Then we have to make lumps of it too. 3) The alumina must then be mixed with some silica lumps and some carbon and roasted with solar energy at high temps to get an Al-Si alloy. 4) This Al-Si alloy will then be purified either by cooling the molten alloy until silicon solidifies and can be screened out or by boiling and condensing out the Al. 5) If we are lucky the reduction can be done with hot CO gas because it is easier to recycle than solid carbon. All you need do is take the CO2 off gas and run it thru a RWGS reactor and electrolyze the water formed to recycle H2. . To recycle solid carbon we must shift CO2 to CO and H2O in RWGS reactors, electrolyze the water to recycle hydrogen, shift the CO to methane and water in sabatier reactors, condense and electrolyze the water, and pryolize the methane on hot refractory bricks and then remove the carbon black.. So when it comes to time, energy and machinery, we need about just as much to get aluminum as steel, and we have very little to alloy it with therefore this will not be the strongest aluminum, but it will make good sheet metal and various products, especially electrical wiring. It could also clad calcium high power cables. Or an alloy of Al and Ca could be used for high tension power cables. Also, steel production has the added benefit of slag production for concrete. Titanium is gotten by 1) electrostatic separation of ilmenite, 2) hydrogen reduction, 3) grinding of the fused Fe and TiO2 particles and 4) treating with hot CO gas to form iron carbonyls that evaporate away from the TiO2. The TiO2 can be used as is for high temp reflectors and solar furnace linings, or it can be 5) electrolyzed in FFC cells to get sponge titanium metal. If there are any iron impurities remaining in it we will 6) beat them out of the sponge metal with big tilt hammers. Looks easy to get titanium, but there is much less titanium than iron in the mare and it takes just as many steps to do it and the FFC cells must be upported from Earth because they have big graphite electrodes in them and require a CaCl2 flux. We might get chlorine from volcanic gas or volcanic glass someday to combine with Ca on the Moon. Titanium is far harder to work with and weld than steel and we have few elements to alloy it with. We have nickel and cobalt to make superalloys of steel, esp. if we upport or discover chromium. Steel and titanium are both heat treated, so nobody can complain about the heat treatment of steel. |
 |