BASIC BRICKS

Basic bricks are made from magnesia (MgO), magnesia-chrome, magnesia-spinel, magnesia-carbon or dolomite raw materials. They resist basic slags rich in CaO and FeO that destroy alumina-silica refractories. They are the standard working lining for BOF and EAF steelmaking, cement rotary kiln burning zones, copper and nickel converters, and non-ferrous smelters.

Magnesia-chrome bricks contain 12–22% Cr₂O₃ and offer the best slag and thermal-shock resistance, but the chrome can leach into hexavalent Cr⁶⁺ during disposal, environmentally regulated. Magnesia-spinel bricks replace chrome with MgAl₂O₄ spinel, giving similar coating-formation behaviour and thermal shock with no Cr⁶⁺ liability. Most modern cement plants now specify magnesia-spinel for the burning zone.

MgO-C bricks are magnesia bricks containing 8–18% graphite plus antioxidants. The carbon prevents slag wetting and improves thermal shock dramatically. They are the dominant working lining for BOF converters, EAF slag lines, ladle slag bands and torpedo car impact zones. Typical service is 2–4 heats per cm of wear.

A modern BOF lined with MgO-C bricks typically runs 3000–5000 heats between full relines, with localised gunning every 50–100 heats. EAF working lining gives 600–1500 heats depending on power-on time, slag chemistry and gunning practice. Cement kiln burning zone basic bricks run 9–14 months between turnarounds.

Yes, magnesia-spinel and magnesia-hercynite (MgO-FeAl₂O₄) grades are now the standard in environmentally-conscious cement plants. They eliminate Cr⁶⁺ disposal liability while delivering equivalent or better burning-zone life. We supply chrome-free grades from CUMI and TRL Krosaki, with full disposal-class certification.

Critical, keep dry. MgO and MgO-C bricks hydrate in humid air, causing dimensional growth and surface spalling. Store in sealed plastic on pallets, preferably in a dehumidified shed. Use within 6 months of receipt. Open pallets only when ready to install. Mortar joints must be 1–2 mm. After installation, dry out within 24 hours to avoid moisture damage.