Steel: the bones of civilization — casting plates, billets, and beams
We cast sunlight into molds. Yesterday, coal furnaces were already replaced by clean arcs; today, we turn liquid "light metal" into the bones of bridges, rails, towers, and tools — quietly, precisely, and quickly.
Why steel (and why now)
Steel is still the strongest poetry of civilization per kilogram. The problem was not the metal — but the smoke. With clean power (3–4 parts) and smart sorting (2 parts), we cast and roll globally without belching into the sky.
- Demand is huge: towers, rails, ships, factories, solar frames, wind towers.
- Electrified process: EAF and electric heating turn shops into grid-friendly neighbors.
- Direct rolling: hot metal straight to the mill = less energy, less time, less drama.
Casting basics (plates, blooms, billets)
Continuous casting (CCM)
Liquid steel flows into a water-cooled mold, forming a skin; the strand is pulled and cut. No huge ingot yards, no "reheating museums" — just a steady river of steel.
Plate: 200–250 mm thick • up to 2,000 mm wide Bloom: 200–350 mm square Billet: 100–180 mm squareCasting speed: plate ~1–2 m/min; billet ~3–6 m/min (depends on grade).
Energy and yields in casting
- Casting electricity consumption: ~20–40 kWh/t (drives, secondary cooling)
- Yield from melt to casting: ~92–96% (trims, intermediate funnel, initial/final parts)
- Hot transfer: directly to the rolling line 700–1000 °C — 60–90% less heating
Electric heating, not flames (why it matters)
Let's heat the steel, not the air
For plates, blooms, and billets, we use induction and resistance furnaces. They transfer energy directly to the metal; nothing escapes up the chimney.
- Full reheating (cold plate → 1,200 °C): ~0.25–0.35 MWh/t
- Hot transfer (700–900 °C → 1,200 °C): ~0.05–0.15 MWh/t
- Rolling drives and assistance: ~0.08–0.15 MWh/t
Numbers include heat recovery and modern drives; design for the upper limit, enjoy the lower.
Why shops like the microgrid
- Predicted work cycles → easy to cover peaks with accumulation.
- Heat recovery → process steam to neighbors (painting, laundry, food).
- No NOx burners → clean air and fewer permits.
Rolling lines and products (what we make)
Hot rolling mill (HSM) — coils
Plates are rolled into coils for cars, household appliances, ship plates, and solar trackers.
- Input: 200–250 mm plate
- Output: 1.2–20 mm strip
- Line electricity: ~0.12–0.25 MWh/t (with hot transfer)
Plate / Steckel — thick plates
Thick, wide plates for wind towers, bridges, ship hulls.
- Output: 10–150 mm plate
- Line electricity: ~0.10–0.20 MWh/t (hot transfer)
Profiles / rods — beams, rails, rebar, wire
Billets/blanks become rebar, H-beams, rails, wire rods.
- Line electricity: ~0.08–0.18 MWh/t (hot transfer)
- Rails: straightness <0.3 mm/m
Memory per ton (steel products)
Electricity (excluding melting)
| Operation | kWh per ton | Notes |
|---|---|---|
| Casting and length cutting | 20–40 | Drives, water |
| Reheating (cold plate) | 250–350 | Induction/resistance |
| Reheating (hot transfer) | 50–150 | Depends on input T |
| Rolling and auxiliaries | 80–150 | Motors, hydraulics |
Total (hot rolled coil): ~0.20–0.40 MWh/t. Total (cold plate): ~0.35–0.50 MWh/t.
Outputs (from melting to final)
| Step | Output, % | Comment |
|---|---|---|
| EAF tapping → casting | 92–96% | Trimmings, intermediate funnel |
| Casting → rolling | 97–99% | Cut ends |
| Rolling → product | 95–98% | Edge trimming, slivers |
Overall: ~85–92% depending on product mix and hot transfer. Scrap returns back to EAF.
Pre-calculated factory scenarios
Scenario A — mini plant (long products, scrap→EAF)
Capacity 1 Mt/year • billets/blooms → rebar, H-beams, rails.
| Position | Value |
|---|---|
| Average throughput | ~125 t/h (8,000 h/year) |
| EAF electricity (melting) | ~0.50 MWh/t → ~62.5 MW |
| Casting + rolling (hot transfer) | ~0.15 MWh/t → ~18.8 MW |
| Total average load | ~80–90 MW |
| PV min. (for daily coverage) | ~410–460 MWp |
| Storage (12 hours) | ~0.96–1.08 GWh |
| Footprint (area) | ~20–35 ha (casting + yard) |
PV minimum based on Avg.(MW)×5.14 (5.5 PSH, 85% DC→AC). Upscaled to supply neighbors.
Scenario B — flat products center (DRI(H₂)+EAF + HSM)
Capacity 5 Mt/year • plates → coils/plates, widely using hot transfer.
| Position | Value |
|---|---|
| Average throughput | ~625 t/h |
| DRI(H₂)+EAF electricity | ~3.5–4.0 MWh/t → ~2.2–2.5 GW |
| Rolling (hot transfer) | ~0.20 MWh/t → ~125 MW |
| Total average load | ~2.3–2.6 GW |
| H₂ consumption | ~250–300 kt/year |
| PV min | ~12–13 GWp |
| Storage (12 hours) | ~28–31 GWh |
| Footprint | ~60–120 ha + nearby PV field |
Electrolyzers make up the majority of power. Rolling is a "polite" segment.
Production mix "handle" (1 Mt/year plant)
| Mix | Coil | Plate | Profiles/bars | Avg. electricity (MW) |
|---|---|---|---|---|
| Many coils | 60% | 10% | 30% | ~86 |
| Balanced | 40% | 20% | 40% | ~82 |
| Many longs | 20% | 10% | 70% | ~79 |
Differences arise from the need for rolling motors and the reheating section; EAF load is similar.
Outputs, quality, and zero waste
Scrap — an advantage, not a disadvantage
- Edge trims, rejects, and cut-offs go straight back into the EAF bucket.
- Melting energy and time from charging to tapping decrease by crushing and preheating on site.
- Billet/coil ends feed a small foundry for castings and mill billets.
Quality assurance — in an interesting way
- Linear gauges: thickness, profile, flatness.
- "Metallurgy on rails": spectrometers at casting; hardness and grain at the coiling machine.
- Traceability: every beam and coil has a digital birth certificate.
Footprint and team (1 Mt/year mini factory)
Area
- Melting shop + casting: ~8–12 ha (closed)
- Rolling and finishing works: ~8–15 ha
- Yards and logistics: ~5–8 ha
- PV field (min.): ~2.0–2.5 km² (nearby)
People and competencies
- Operator teams for each workshop (3 shifts), strong automation base.
- Electricians > burner masters (designed that way).
- Metallurgists, quality, supervision, and a lemonade stand for visiting school tours.
Questions and answers
"Are beams and coils really from the same melt?"
Yes — sheets for coils/sheets and blanks/blooms for profiles/bars come from parallel casting streams. The same chemistry, different shapes, the same — no — fumes.
"What about galvanizing and coating?"
Nearby. Electric annealing lines, zinc/aluminum baths, and coil coating lines live in the same microgrid, sipping excess solar energy from part 3.
"Can we charge everything hot?"
Almost. Smart buffers maintain the current temperature up to rolling; when a pause is needed, the gap is filled by electric reheating — without "fire dragons."
Next: Aluminum, copper, and rare metals — power veins (part 6). Wires, light alloys, and battery metals — the nervous system of our bones.