The 
Etrionic Blast Furnace is your gateway to 
Steel, the metal behind nearly every Ad Astra machine and your first rocket. It works like an upgraded 
Blast Furnace that runs on energy instead of fuel, and it smelts ores four times faster thanks to four parallel slots. It also has a second mode that fuses Iron and Coal directly into Steel.
Once you have a 
Coal Generator or 
Solar Panel supplying power, this furnace becomes the heart of your early base. Set it to bulk-smelt a backlog of ores, then flip it to alloy mode whenever you need more Steel. Everything from the 
NASA Workbench to the 
Launch Pad depends on the metal it produces.
Obtaining
You craft the Etrionic Blast Furnace by wrapping a vanilla Blast Furnace in 
Iron Plates. Place the Blast Furnace in the center, fill the top and bottom rows with six Iron Plates, and put a 
Redstone Dust on each side.
The Iron Plates are the gating ingredient here. You make them in a 
Compressor, which is the machine you should build right before this one. See the Steel and the Compressor article for the full plate-making process.
Usage
Right-click the placed furnace to open its menu. The four input slots sit on the left and the four output slots sit on the right, with a battery slot and an energy gauge alongside them. A button in the menu switches the furnace between its two modes, Blasting and Alloying.
The furnace cannot do anything without power, so feed it energy before loading materials. Drop a charged battery or 
Etrionic Capacitor into the battery slot, or run a cable to it from a Coal Generator, Solar Panel, or other source. When it has power and a valid recipe, the front lights up to show it is working.
Unlike a vanilla Blast Furnace, this machine burns no Coal or wood. If nothing is happening, check that energy is reaching it from a generator or a charged battery in the battery slot.
Supply Power
Connect the furnace to an energy source with cables, or place a charged energy item in the battery slot. It holds up to 20,000 energy and draws a small, steady amount while it runs. You can also place a Coal Generator directly against the furnace, which pushes power into any adjacent machine without cables.
Pick a Mode
Press the mode button to choose Blasting or Alloying. Blasting smelts ores into ingots, while Alloying combines materials into Steel. Double-check this: if you are trying to make Steel, the furnace must be in Alloying mode.
Load the Slots
Add your ores to the four input slots for Blasting, or add 
Iron Ingots and 
Coal for Alloying into Steel Ingots. In Blasting mode all four slots work at the same time, so spread different ores across them to process several stacks at once.
Collect the Output
Finished ingots and alloys appear in the four output slots on the right. You can pull them out by hand or pipe them away for automation.
Modes
The furnace does two very different jobs depending on which mode you select. Blasting is your high-volume ore smelter, and Alloying is how you actually create Steel. You can switch between them at any time from the menu.
In Blasting mode the furnace runs through any recipe a normal Blast Furnace can, including vanilla ores and every space ore you mine off-world such as 
Desh, 
Ostrum, and 
Calorite. The big advantage is the four slots, which all smelt together for roughly four times the output of a single Blast Furnace.
In Alloying mode the furnace pulls ingredients from those same four slots and fuses them into an alloy. The mod ships with one alloy recipe, and it is the important one. Loading Iron and Coal produces one Steel Ingot per Iron and Coal pair.
Charcoal works in place of Coal as the carbon ingredient, so a stack of leftover Charcoal does the job just as well. If you load Iron and Coal but nothing happens, the furnace is still set to Blasting; flip it to Alloying and the Steel starts cooking.
Blasting
Alloying
Mechanics
The furnace stores up to 20,000 energy and accepts a steady trickle of incoming power, so a single Coal Generator is enough to keep it fed early on. Blasting draws a small amount of energy for each slot that is actively smelting, so running all four costs more power but clears ore far faster. Alloying draws power the whole time it is fusing a Steel Ingot.
You can configure each side of the furnace to pull items in, push results out, or accept energy, which lets you automate it with item pipes and cables. You can also set its Redstone behavior if you want it to pause on a signal.
For most early setups, a generator wired straight into the furnace and a 
Hopper on the output is all you need. You can also set one face to pull Iron and Charcoal from an adjacent barrel and the opposite face to push finished ingots into a second barrel, letting the furnace run unattended without a single pipe.
Recipes
Steel is the standout recipe and the reason you build this furnace. Set it to Alloying mode and feed it Iron Ingots and Coal (or Charcoal) to produce Steel, which you will need for the Nasa Workbench, the Launch Pad, and the Tier 1 Rocket. Stockpile plenty, because almost every later machine asks for it.
For everything else, switch to Blasting mode and treat it as a faster Blast Furnace. It handles vanilla ores and raw metals, and it is the standard way to smelt the space ores you bring home from the Moon, Mars, and beyond.
FAQ
Build an Etrionic Blast Furnace, power it, and set it to Alloying mode. Add Iron Ingots and Coal to the input slots, and it will produce one Steel Ingot for each Iron and Coal pair. Charcoal works in place of Coal if that is what you have on hand.
It almost always comes down to power, since this furnace runs on energy and never on fuel. Make sure a generator is wired to it or that a charged battery sits in the battery slot. Also confirm you are in the correct mode for the items you loaded; loading Iron and Coal while the furnace is still set to Blasting produces nothing. Switch it to Alloying to make Steel.
In Blasting mode it smelts roughly four times as fast, because all four input slots process at the same time. Load a different ore into each slot to clear a large backlog quickly.
Anything a vanilla Blast Furnace accepts, plus the space ores from Ad Astra. That includes Iron, Gold, and other vanilla ores along with Desh, Ostrum, Calorite, and Ice Shard ores you mine on other planets.
Run a cable to it from a Coal Generator or Solar Panel, or place a charged energy item like an Etrionic Capacitor in its battery slot. It stores up to 20,000 energy and only needs a small, steady supply to keep smelting. You can also place a Coal Generator directly against the furnace, which transfers power without any cables.
