Refractories for Iron and Steel: Blast Furnace, Converter, EAF, Ladle, Tundish and Consumption per Tonne

Refractories for iron and steel line every vessel from the blast furnace to the reheating furnace, and steelmaking consumes them at 10 to 20 kg per tonne of steel (20 to 40 lb per short ton) worldwide (Nippon Steel, 2020). Which refractory class sits in which zone, and why is a slide gate replaced within hours while a hot blast stove lasts two blast furnace campaigns? Steel plant refractories are a subset of refractory materials, whose definitions and classes start under refractory materials.

Refractories in steelmaking, also called steel refractories or, in trade shorthand, refractory steel, form the largest consuming market, and their classes, campaigns and costs differ by vessel and zone.

Converter MgO-C brick carries 15 to 20 mass % graphite, unshaped products make up 60 to 70 % of steelmaking refractory consumption in Japan, and magnesia brick is specified under ASTM C455-07(2022) or ISO 10081-2:2003.

Every value names its standard and edition, the product data sheet or the dated source it comes from; see our methodology and fact-checking process.

What Is Refractory in the Steel Industry?#

Refractory in the steel industry means the nonmetallic linings (bricks, castables, gunning mixes and fiber products) that hold molten iron, steel and slag at up to 1800 °C (3,272 °F) (RHI Magnesita, 2025). ASTM C71-12(2024) sets the US boundary: refractories serve environments above 538 °C (1,000 °F).

Steel uses these materials as consumables. The World Refractories Association separates consumable refractories, continually replaced as in steelmaking, from investment refractories such as glass furnace linings.

Consumable Linings: Why Steel Takes the Largest Share of Refractory Raw Materials#

Steel takes the largest share because its linings are consumed in service and replaced in cycles of 20 minutes to 2 months (RHI Magnesita, 2021 company estimate). The same estimate gives yearly relines for cement and lime kilns.

Three published figures size the steel share of refractories by industry. Compson and Gross (2021) put iron and steel at 60 % of the refractory raw materials market; Nippon Steel (Technical Report No. 125, 2020) estimates about 27 Mt (about 30 million short tons) of refractories for steel per year; the World Refractories Association states that around 70 % of refractories are sold to the steel industry. The nine consuming industries are compared under refractories by industry.

Steel Plant Vessels, Zones and Lining Classes#

Iron and steel plants have six refractory-lined vessel types, from the blast furnace with its hot blast stoves to the reheating furnace, and each splits into zones with their own wear mechanism and lining class. Table 1 compares them, with coke ovens upstream as a related plant; values in this section and the next three come from Nippon Steel Technical Report No. 125 (2020) unless another source is named.

Ironmaking Zones: Hearth, Bosh, Stack and Hot Blast Stoves#

The blast furnace hearth carries most of its heat load at the wall, with a wall-to-bottom heat flow of about 80:20 (Saint-Gobain producer document). Hot blast stoves heat the blast to about 1200 °C (2,192 °F), and their silica zone exceeds 1400 °C (2,552 °F); stove silica brick has more SiO2 and less liquid phase than coke-oven silica. The torpedo ladle is the ironmaking transfer vessel.

Steelmaking Zones: BOF Converter and Electric Arc Furnace#

The BOF converter is lined with MgO-C brick in all parts, and the EAF uses MgO-C at its hot spots and sidewall. Converter practice treats the trunnion and the charge belly as separate wear zones. The EAF runs intermittently, so its hot spots and sidewall see thermal cycling between heats.

Secondary Metallurgy and Casting Zones: Ladle and Tundish#

A steel ladle has five zone groups (slag line, metal zone, bottom with impact area, permanent lining, and purging and slide gate parts), and a tundish has a permanent lining, a wear lining and a MgO coating. Tundish steel runs at about 1500 to 1570 °C (2,732 to 2,858 °F), about 100 °C (180 °F) below the ladle, in tundishes of up to about 80 t (88 short tons).

Rolling-Mill Zones: Reheating Furnace Walls, Roof and Skids#

Reheating furnaces run at about 900 to above 1300 °C (about 1,652 to above 2,372 °F), with ceramic fiber walls and roofs and insulated skids. Nippon Steel has run all-fiber reheating furnaces since July 1986 (Kimitsu plate mill).

Working, Safety and Insulating Layers in Steel Vessels#

Steel vessels are lined in layers: a working lining that meets metal and slag, a permanent or safety lining behind it, and insulation at the shell where heat loss matters. Ladle permanent linings are high-alumina brick in most cases, in two or more layers where possible; tundishes add optional shell insulation.

Heat loss decides the insulating layer of a refractory lining in reheating furnaces. In one plant example (Oita hot strip mill), skid heat loss is 25 % of the furnace heat loss, about four times the shell loss; layer thicknesses and anchoring are planned under refractory lining design.

Materials by Zone: Refractory Classes for Each Steel Plant Vessel#

Steel plant zones are lined with distinct refractory classes: carbon and SiC in the blast furnace, silica and checker brick in the stoves, MgO-C in converter, EAF and ladle slag line, and castables, flow control parts and fiber downstream. Table 2 gives one class per zone and the reason it sits there.

MgO-C and AMC Bricks in Converters, EAFs and Ladles#

MgO-C replaced dolomite-carbon in converters from the late 1970s and now lines all converter parts, after it was first developed for EAF hot spots.

Ladle slag lines take MgO-C where ladle furnaces run basic desulfurizing slags and magnesia-chrome brick where slags are less basic and no ladle furnace runs (HarbisonWalker International ladle brochure, 2025). In AMC bricks for ladle bottoms and impact areas, tabular alumina outperforms brown fused alumina (Compson and Gross, 2021).

Spinel-Forming Castables for Ladle Walls, Bottoms and Impact Areas#

Alumina-spinel castables from the late 1980s, then alumina-magnesia castables from the early 1990s, replaced brick in Japanese ladle metal zones, while MgO-C stayed in the slag line. Before them, Japanese ladles moved from roseki brick to zircon brick in the 1960s.

In service, these castables form magnesium aluminate spinel (MgAl2O4) and calcium hexaluminate (CA6), which densify the structure against slag penetration. European ladles add synthetic alumina sidewalls for aluminum- and silicon-killed steels (Compson and Gross, 2021); spinel grain grades are compared under magnesium aluminate spinel.

Carbon, Silicon Carbide and Ceramic Cup Linings in the Blast Furnace#

Blast furnace hearths use carbon blocks protected by a ceramic cup, and the bosh, belly and stack use nitride- or SiAlON-bonded SiC or SiAlON-bonded corundum. The ceramic cup protects the carbon until a skull reaches equilibrium. A Saint-Gobain document chooses the bosh and belly grade by thermal conductivity: low conductivity saves energy, high conductivity promotes a protective skull.

Flow Control Parts and Tundish Working-Lining Masses#

Flow control parts are carbon-bonded: slide plates and nozzles belong to the carbon-alumina system, and submerged entry nozzles are alumina-graphite with a zirconia-graphite slag band stabilized by CaO or Y2O3. Ladle purging plugs are mullite, alumina, magnesite-chrome or magnesia. The tundish MgO coating, sprayed or dry vibrated over the Al2O3-SiO2 castable wear lining, is renewed after each sequence.

Binders and Additives in Steel Plant Refractories#

Steel plant refractories depend on four binder and additive groups, split between carbon-bonded brick and castables. The four groups are listed below.

• Graphite and carbon binders in MgO-C and AMC brick.
• Metal and carbide antioxidants in the same brick.
• Calcium aluminate cement at low levels, or cement-free binders, in ladle castables.
• Dispersants and steel fibers in ladle and tundish castables.

Graphite, Resin Binders and Antioxidants in Carbon-Bonded Bricks#

Converter MgO-C carries 15 to 20 mass % graphite, and Nippon Steel (2020) relates higher graphite contents in EAF brick to intermittent operation. Magnesia fines of 0.1 mm (0.004 in) and below are reduced to suppress the MgO-carbon reaction.

Antioxidants for carbon-containing refractories, such as aluminum, silicon and boron carbide, react with O2 and CO before the carbon does and densify the matrix. The carbon bond comes from phenolic resin, mixed cold, or coal tar pitch, high temperature (CTPHT), mixed hot; CTPHT carries the line "Harmonised CLP Annex VI: H340, H350, H360FD", and its EU use after 2020-10-04 needs an authorization under REACH Annex XIV entry 41 (Commission Regulation (EU) 2017/999). The metals and carbides are compared under antioxidants for carbon-containing refractories.

Cement Level, Dispersants and Steel Fibers in Ladle and Tundish Castables#

Ladle castables use calcium aluminate cement at low levels or cement-free binders, with magnesia fines that form spinel in service. The magnesia dose is optimized because spinel and CA6 formation expands the castable and an excess causes thermal stress cracking.

Nippon Steel's ladle developments add a high-performance dispersant that lowers casting water and a SrO-Al2O3 cement that melts higher than calcium aluminate cement.

Steel fibers in refractory castables reinforce the tundish wear lining: in one Nippon Steel trial (2020), raising them from 2 to 3 mass % extended lining life by 15 % and cut repair material by 10 %. Fiber grades are covered under stainless steel fibers for refractory castables.

Wear Mechanisms in Steel Plant Linings#

Steel plant linings wear by four mechanisms: slag corrosion and penetration, oxidation of carbon in MgO-C and AMC brick, thermal spalling from batch operation, and FeO scale and flame attack on reheating furnace skids.

Carbon oxidation affects every carbon-bonded zone, from converter and EAF brick to the ladle slag line. It starts where oxygen reaches the carbon, and the antioxidants react with O2 and CO first; ISO 10081-3:2003 marks antioxidant-containing grades with the suffix A.

Slag Attack at the Ladle Slag Line and on Slide Plates#

Slag corrosion governs the ladle slag line, which is why that band takes MgO-C or magnesia-chrome brick while the metal zone takes alumina-magnesia castables. Slag basicity decides between the two brick classes, and tests ranking brick against slag and chemical attack are explained under slag and chemical attack.

Below the slag line, ladle castables peel after slag penetration. Calcium-treated steel attacks Al2O3-ZrO2-C slide plates by mullite decomposition and calcium penetration, which led to MgO-C, ZrO2-C and CA6 plates.

Batch Cycling, Spalling and Scale in Steel Vessels#

Ladles and EAFs cycle between empty and full, so their linings spall thermally, while reheating furnace skids lose fiber rings and castable to scale, flame impingement and thermal cycling.

Ladle castables also fail by excessive sintering. Thermal spalling reflects limited thermal shock resistance, and its measurement is covered under thermal shock resistance.

Specific Refractory Consumption per Tonne of Steel and Campaign Life#

Specific refractory consumption in steel is 10 to 20 kg per tonne of steel (20 to 40 lb per short ton) worldwide, and campaign life ranges from hours for a slide gate to two blast furnace campaigns for a hot blast stove. Table 3 lists the metrics with basis, scope and year.

Consumption per Tonne and Global Tonnage#

Nippon Steel (Technical Report No. 125, 2020) puts specific refractory consumption at 10 to 20 kg/t steel (20 to 40 lb per short ton). Its global estimate uses 15 kg/t (30 lb per short ton) and arrives at about 27 Mt (about 30 million short tons) of refractories for steel per year.

Unshaped products, such as castables, gunning mixes and spray masses, make up 60 to 70 % of steelmaking refractory consumption in Japan (Nippon Steel, 2020), leaving 30 to 40 % to shaped brick.

Campaign Life and Relining Intervals by Vessel#

Campaigns differ by more than three orders of magnitude between vessels, from a slide gate that may need replacing every 4 hours to a hot blast stove that serves two blast furnace campaigns. RHI Magnesita (FY2024 results, 2025-02-27) puts primary steelmaking furnace relines at about six-month intervals.

Converter linings are counted in heats rather than months, and their zone-by-zone campaign data sit on the converter page.

Refractory Cost per Tonne of Steel#

Refractories cost around 2 to 3 % of steelmaking operating costs on average (RHI Magnesita FY2024 results, 2025-02-27). In Europe in 2012, ladle refractories cost EUR 1.50 to 2.00 per t of steel (EUR 1.36 to 1.81 per short ton), per a 2012 seminar paper cited by Compson and Gross (2021).

Heat loss turns lining quality into cost: Tata Steel IJmuiden (refractories WORLDFORUM, 2017) puts 1 °C (1.8 °F) on 1 t of liquid steel at 4 to 10 eurocents (3.6 to 9.1 eurocents per short ton). These are dated cost factors for comparing quotes, not prices.

Installation, Dry-Out and Hot Repair in Steel Plants#

Steel plant linings are installed by bricklaying, casting, dry vibration behind a steel former, gunning and spraying, dried slowly at 300 °C (572 °F) and below, and kept in service by hot gunning and slag coating.

Ladle Dry-Out Below and Above 300 °C#

Ladle castables are heated slowly at 300 °C (572 °F) and below and then held above 300 °C to remove residual moisture, which controls explosive spalling (Nippon Steel, 2020).

Drying method sets the time and energy of a refractory dry-out. In a Nippon Steel (2020) comparison for a 100 t (110 short ton) ladle, a gas burner needs 24 h and 11.3 million kcal (47.3 GJ); hot air at 250 °C (482 °F) plus microwave heating at 5.3 kW per t of refractory (4.8 kW per short ton) needs 8 h and 2.2 million kcal (9.2 GJ). Hold temperatures by castable type are set out under refractory dry-out and heat-up schedules.

Hot Repair and Lining Thickness Measurement#

Ladles are measured with a laser profile meter for residual thickness and then hot-gunned, and their shells are watched by infrared thermography (Nippon Steel, 2020).

BOF linings are also protected between heats by a blown slag coating, the practice known as slag splashing.

Refractory repair and maintenance of ladle castables uses wet gunning or continuous kneading-gunning, and these methods are compared under refractory repair and maintenance.

Standards and Quality Control for Steel Plant Refractories#

Steel plant bricks are classified under ASTM C455-07(2022) and ISO 10081-2:2003 for magnesia and magnesia-chrome grades and under ASTM C27-98(2022) and ISO 10081-1:2003 for fireclay and high-alumina grades. Cold crushing strength is tested to ASTM C133-24 or EN ISO 10059-1:2025.

Carbon-containing brick has its own pair: ISO 10081-3:2003 groups MgO-C and related carbon-containing basic types (MC, MLC, MDC, DC) by residual carbon from 7 to below 50 %, and ASTM C831-18(2023) measures residual carbon of coked brick. The ASTM and ISO documents are not equivalent, so a specification names one system and edition; Table 4 sets them side by side.

Refractory inspection and quality control starts at receipt, and some steel plants run quality tests on deliveries (Tata Steel IJmuiden, 2017). Sampling plans and thermography are covered under refractory inspection and quality control.

Contractor Match and Supplier Quotes for Steel Plant Linings#

Steel plant relines, dry-outs and hot repairs are contracted per vessel, and a request names the vessel, zone, lining class and campaign target. A full-service quote can cover supply, installation, wrecking and waste per tonne of steel (Tata Steel IJmuiden, 2017).

How Do Steel Plant Refractories Connect to Other Refractory Questions?#

Steel plant refractories share their classes, raw materials and practice with other industries, while the steel-specific answer always starts from the vessel and zone.

Wrecking turns every lining into spent refractory, and in most cases more than half of installed refractory ends as waste (Tata Steel IJmuiden, 2017). Tear-out of spent magnesia-chrome brick falls under the hexavalent chromium (Cr(VI)) limits of OSHA, 5 µg/m³ with an action level of 2.5 µg/m³ (29 CFR 1910.1026, eCFR text of 2026-10-27), and of the EU, 0.005 mg/m³ since 2025-01-18 (Directive (EU) 2017/2398). Sorting routes are covered under spent refractory recycling.

Is "Refractory Steel" a Heat-Resistant Alloy?#

No: on this page "refractory steel" means the refractories that line steelmaking vessels; heat-resistant alloys and refractory metals are a different subject and are not covered here.

Which Raw Materials Go Into Steel Plant Refractories?#

Steel plant refractories use magnesia (sea-water and natural, fused and sintered), flake graphite, tabular and fused alumina and spinel; iron ore, coke and flux are not refractories.

Among refractory raw materials, magnesia and flake graphite make MgO-C brick, and tabular alumina and spinel make ladle castables; each grain is profiled under refractory raw materials.

How Do Steel Linings Differ From Other Industry Linings?#

Seven other industries line their vessels with partly the same classes, listed below.

• cement kiln refractory: cement and lime kilns.
• glass furnace refractories: fused cast, silica, zircon and regenerators.
• aluminium furnace refractory: melting and holding furnaces, anode baking, reduction cells.
• copper smelter refractory: copper, nickel and other non-ferrous smelters.
• petrochemical refractory: FCC units, fired heaters, reformers, gasifiers.
• boiler refractory: utility, CFB, biomass and waste-to-energy boilers.
• induction furnace lining: ramming mass, sintering and lining life.