Salt works for your factory.

Magnesium doesn't come out of the ground. It comes out of the water. Lay out evaporation ponds, pipe in water and let the sun do the work: out comes bittern, a magnesium-rich brine, and your chemical plants turn it into magnesia and the light metal that robots, rockets and space platforms are made of.

The catch is the sun. Ponds run at full speed at noon, slow down at dusk and stop at night. A salt works that feeds your factory around the clock needs tanks to get through the dark, or more land, or heated evaporators that run on heat pipes day and night on a fraction of the space. And since low density structures, robot frames and electric furnaces all need magnesium, every rocket you launch grows the pond field.

No ore patches, no mining outposts. Wherever there is water, there is magnesium.

Factorio 2.1. Works on its own, and fits into Space Age, Space Exploration, Krastorio 2, the BZ mods and the Timeken, Ashier and trikop metal mods, all optional.

What it adds

• Evaporation ponds (12×12, no power, no steel): water → bittern. Speed follows the sun. Alt-mode shows each pond's sunlight.
• Magnesia (bittern + stone), magnesium (magnesia + coal) and magnesium chloride (bittern), in chemical plants.
• Heated evaporators (5×5, after Nuclear power, or after Phosphorus processing with Phosphorus): the same recipe on heat-pipe heat, day and night, as fast as about two and a half ponds.
• Polymerisation catalyst: catalysed plastic makes a third more plastic from the same ingredients. The catalyst comes back 98% of the time.
• Ductile iron pipe (a fifth more pipe from the same iron) and Sorel concrete (magnesia instead of stone bricks, sets twice as fast).

Magnesium is needed for low density structures (half their copper becomes magnesium), flying robot frames and electric furnaces (magnesia refractory). Utility science and rockets therefore need a growing salt works: about six ponds per utility science pack per second.

Space Age

Pond speed follows each planet's solar power: 400% on Vulcanus (bring ice to melt), 50% on Gleba, 20% on Fulgora, 1% on Aquilo, where heated evaporators take over. Ponds cannot be built on space platforms.

Space platform foundations use magnesium and weigh 15 kg instead of 20, so a rocket carries 66 instead of 50. Cast low density structures take magnesium like the handcrafted ones, and calcite precipitates more magnesia.

Space Exploration

With or without Krastorio 2.

• Ponds follow each planet's sun and climate: faster on hot, dry worlds, slower on cold, wet ones. They stay on the ground; heated evaporators run on reactor or energy-beam heat on dark worlds.
• Heat shielding takes magnesia, so every rocket part, cargo rocket section and delivery cannon capsule needs a salt works.
• Aeroframe poles take magnesium. With Krastorio 2, a magnesium-lithium pole needs half the beryllium.
• Magnesiothermic reduction: magnesium turns beryllium powder and holmium chloride into more metal than the standard routes.
• Magnesium, magnesia and magnesium chloride travel by delivery cannon.

Krastorio 2 and BZ

Magnesium arrives with chemical plants, so it comes early in Krastorio 2. It never moves another mod's research to a later science tier, and its alternative recipes are built from the recipes your pack actually uses.

• Krastorio 2: mineral water evaporates into twice the bittern, or into bittern and lithium chloride. Quicklime precipitates more magnesia; coke replaces coal (graphite and charcoal as alternatives).
• BZ Aluminum: magnesium is the alloying metal in aluminum 6061 and 2219, so it reaches every low density structure, and trains, roboports and cargo ships.
• Chlorine (Krastorio 2, BZ Chlorine): magnesium chloride electrolysis (more magnesium per bittern, plus chlorine), salt pans, and the Kroll process with BZ Titanium: the most titanium per ore, and the magnesium comes back as chloride.
• BZ Silicon, Tin, Foundry, Gold, Zirconium: the Pidgeon process (silicon reduces magnesia, no coal), magnesiothermic silicon, Grignard organotins, and magnesia foundry linings and catalyst supports.

Metal mods

• Tantalite: magnesium reduces tantalite to more tantalum and niobium per ore.
• If I Had A Nickel: magnesia precipitates more nickel from sulfuric acid leach.
• BrimStuff, Them Thar Hills: magnesia neutralises chemical waste and depleted acid into water.
• Limestone: lime precipitation keeps its calcium chloride.
• BrassTacks: zinc-magnesium coated steel needs half the zinc.

Sibling mods

• Cadmium: magnesia can replace coal in scrubber filters, a third more filters per steel.
• Tellurium: magnesium chloride leaching gets a quarter more tellurium dioxide out of the same residue.
• Phosphorus: heated evaporators run on combustion tower heat, so heated evaporation no longer waits for nuclear power. Phosphorus lines its furnace with magnesia, sets magnesium phosphate cement, and makes catalysed plastic the best plastic of all.
• Gallium: crystal pullers are lined with magnesia insulation, and magnesia-assisted extraction gets seven gallium instead of five out of the same mineral residue.
• Neodymium: magnesia neutralises the monazite leach for a fifth more liquor, and an optional low density structure uses a magnesium–rare-earth alloy.
• Caesium: magnesium reduces caesium metal instead of coal, and an optional magnesia recipe recovers one caesium carbonate per 2,000 crafts from the bittern.
• Antimony: magnesia lines Antimony's annealing chambers when available at the workshop's research tier. Its 400 °C process heat also runs heated evaporators through process conduits: three 1 MW heaters supply one 3 MW evaporator at full speed after warm-up.

Settings

• Unmodified recipes (startup): host recipes to leave alone, e.g. low-density-structure, flying-robot-frame.
• Ponds follow the sun (map): when off, ponds always run at full-sun speed.

Credits

• Evaporation pond: tirisabella, Johanna Spieker and _traum (Sosciencity Graphics, CC BY 4.0), recoloured.
• Heated evaporator: Hurricane046 (Hurricane Graphics, MIT).
• Magnesium icons: MrSmoothieHuman1 (Periodic Madness, MIT).
• Titanium tetrachloride icon: Malcolm Riley (unused-renders, CC BY 4.0).

Full license texts are in THIRD-PARTY-NOTICES.txt inside the mod.