Hot blast furnace

Layers +4 to +5 (the same course)

#	Colour	Name	Matches
1		Refractory bricks (Tier 3)	game:refractorybricks-good-tier3
2		Blast Furnace Core	siex:blastfurnacecore-*
3		Iron Tap	iiex:furnace-irontap-w
4		Slag Tap	iiex:furnace-slagtap-e
5		Tuyere	iiex:furnace-tuyere-*
6		Pipe Outlet	iiex:pipe-outlet*
7		Reinforced Hopper	siex:hopperreinforced
8		Bell Hopper	siex:hopperbell
9		Empty (air, or a pile of coal, or a furnace chargepile)	*:@(air|coalpile|furnace-chargepile)
10		Empty (air, or a pile of coal, or a furnace chargepile, or hearthmetal)	*:@(air|coalpile|furnace-chargepile|hearthmetal-.*)
11		Empty (air)	game:air

Materials

Block	Cells
Refractory bricks (Tier 3)	99
Blast Furnace Core	1
Iron Tap	1
Slag Tap	1
Tuyere	2
Pipe Outlet	2
Reinforced Hopper	1
Bell Hopper	1

Facings and connectors

• Iron Tap turns with the structure; segment 3 of its code names the face.
• Slag Tap turns with the structure; segment 3 of its code names the face.
• Connectors on the north face: cell 0,1,-1.
• Connectors on the south face: cell 0,1,1.

What it is

The steel tier's ironmaking furnace is a nine-course tower of tier 3 refractory brick, a 3x3 shaft over a two-cell hearth, tuyeres in two walls and the taps in the other two, exhaust outlets at the throat, and a sealed top charged through the hoppers above it. It is built around a Blast Furnace Core, which starts it and sets the frame everything else is measured from. Ironmaking in the hot blast furnace explains how it runs.

Build order

1. Stand where the furnace will go and place the core in the floor of the hearth. Everything else is measured from it, and its facing sets the frame for the whole build.
2. Ctrl plus shift and right-click the core to project the build outline, and keep it up while building. It shows which cell wants which block.
3. Lay the hearth course: the core, the two crucible cells, the tuyere on each side of the core and the two taps. Leave the crucible cells empty.
4. Build the brick walls up around the shaft, course by course. Every wall cell is tier 3 refractory brick; tier 1 and tier 2 will not complete the structure.
5. Five courses above the hearth, set the two pipe outlets with the single air cell between them. That gap is the throat and has to stay clear.
6. Above the throat, place the Bell Hopper, and directly on top of it the Reinforced Hopper.
7. Leave the cell each tap points at empty. The drawing does not claim it, and a tap with a wall in front of it has nowhere to pour.

Orientation

The taps and the tuyeres are pinned to a facing: the iron tap faces into the hearth from one wall, the slag tap from the opposite wall one course higher, and the tuyeres face in from the other two. One of them placed the wrong way round leaves the structure incomplete and the readout only says how many cells are wrong, so check the outline rather than the count.

The two outlets are not pinned. Any orientation of a pipe outlet completes the structure, and a wrongly turned one then joins nothing while the furnace reports no fault.

The hoppers sit on the centre line, so the furnace's facing never moves them.

First run

1. Pipe the two tuyeres to a blast main and the two outlets to cowper stoves and a smoke stack, with a relief line to the stack behind a pressure valve set below 1 atm.
2. Put a molten canal or a casting bed under the iron tap's spout, and another under the slag tap's.
3. Fill the Reinforced Hopper with burden and let the Bell Hopper drip it in, then fill with coke, and keep alternating. Dropping is on by default.
4. Start the blower and let the blast main come up to the pressure the burden wants: 2.0 atm for a 20 % coke burden, more for a leaner one.
5. Open the iron tap and right-click it with a torch. The shaft catches only if every column has charge in it and fuel at the bottom.
6. Watch the readout climb past 1482 C and the hearth fill. Tap the iron into the canal, and drain the slag out of the upper tap as it builds.

What goes wrong

It will not complete. Wall brick of the wrong tier, or a tap or tuyere facing the wrong way. Both read the same way: a count of wrong cells.

It lights and goes straight out. The blast was not running before the torch went in, or a column is empty in front of a tuyere.

It burns and never melts. Cold blast. A full furnace on cold blast runs about 60 C short of iron's melting point.

It reports choked. The exhaust run is full. Give it a smoke stack or a second stove.

A tap pours nothing. Metal does not back-flow. A tap needs an empty cell and a canal or bed to pour into, or the metal freezes in the spout.

The bell drips nothing. A bell with no tank above it, or standing clear of a furnace, simply holds what it has: it pulls nothing and drops nothing, and neither block says why.