Supply Magnesia Brick

High-Quality Refractory Solutions for Blast Furnace Ironmaking

Introduction

Blast furnaces, the core equipment of ironmaking, operate under extreme conditions—sustained temperatures of 1400℃-1600℃, aggressive alkaline slag erosion, molten iron immersion, and intense mechanical wear. Refractory bricks are the lifeline of blast furnaces, directly determining operational stability, service life, and production efficiency. Among these critical materials, magnesia bricks stand out as the preferred choice for key high-wear, high-corrosion zones, thanks to their exceptional alkaline slag resistance, high-temperature stability, and structural durability.

This guide focuses on refractory brick selections tailored to specific blast furnace zones, with a core emphasis on magnesia brick specifications, supply capacity, pricing, and procurement terms for bulk buyers. Key refractory bricks for blast furnaces include magnesia bricks, carbon bricks, high-alumina bricks, and spinel bricks, but we prioritize magnesia-based solutions—their unique properties make them irreplaceable for blast furnace hearth, bosh, and shaft lower zones. Whether you’re sourcing for a new blast furnace construction or a maintenance upgrade, this article provides actionable insights to streamline your procurement process.

Refractory Bricks by Blast Furnace Zone

Blast furnaces are divided into distinct zones with varying operating conditions, requiring refractory bricks tailored to specific challenges. Below is a detailed breakdown of zone-specific requirements, with a focus on magnesia brick applications and performance.

Hearth & Bottom (Molten Iron Contact Zone)

The hearth and bottom are the most critical blast furnace zones, immersed in molten iron (1500℃-1600℃) and slag for long-term continuous operation. They endure high hydrostatic pressure, carbon dissolution erosion, and extreme thermal stress—demanding refractories with uncompromising corrosion resistance and structural integrity.

The core refractory solution here centers on magnesia bricks: high-purity magnesia bricks (MgO ≥90%) are installed in the lower sidewalls of the hearth, where resistance to alkaline slag and molten iron penetration is paramount. These bricks form a dense protective layer when reacting with slag, preventing further erosion and extending zone service life. Carbon bricks (fixed carbon ≥90%) complement magnesia bricks in the furnace bottom and upper hearth, leveraging their low permeability to block molten iron seepage.

Magnesia brick performance parameters for this zone include a maximum service temperature of 1700℃, slag erosion rate ≤0.12mm/h, compressive strength ≥70MPa, and apparent porosity ≤18%. These metrics ensure the bricks withstand 3-5 years of continuous operation without premature degradation—a critical factor for minimizing blast furnace downtime.

Bosh & Belly (High-Wear & Erosion Zone)

The bosh and belly zones operate at 1200℃-1400℃, facing high-velocity gas scouring, impact from ore and coke charging, thermal shock from temperature fluctuations, and aggressive alkaline slag erosion. Refractories here must balance wear resistance, thermal shock stability, and corrosion resistance—making magnesia-alumina spinel bricks (a magnesia-based composite) the ideal choice.

Magnesia-alumina spinel bricks (MgO 15-25% + Al₂O₃ 70-80%) combine the alkaline slag resistance of magnesia with the thermal shock stability of alumina, addressing the zone’s dual challenges. Their spinel crystal structure reduces thermal expansion mismatch, enabling them to withstand ≥35 thermal shock cycles (1100℃→20℃) without cracking. High-alumina bricks (Al₂O₃ 75-85%) are used in the upper belly, where mechanical wear is the primary concern, but magnesia-alumina spinel bricks remain the core solution for the lower bosh.

Performance parameters for these magnesia-based bricks include wear resistance ≥95%, linear shrinkage ≤0.2% (1500℃×5h), and compressive strength ≥65MPa. A major Chinese ironmaking plant reported a 40% extension in bosh zone service life after switching to our magnesia-alumina spinel bricks, reducing maintenance frequency and costs.

Shaft (Mid-Temp Zone)

The shaft operates at 800℃-1200℃, with conditions characterized by gas-solid reaction corrosion, moderate thermal shock, and low-to-moderate slag erosion. While the upper shaft relies on cost-effective medium-high alumina bricks (Al₂O₃ 60-70%), the lower shaft—adjacent to the bosh—benefits from magnesia composite bricks (MgO 30-40% + Al₂O₃ 50-60%) to enhance slag resistance.

These magnesia composite bricks bridge the performance gap between standard alumina bricks and high-purity magnesia bricks, offering acid/alkali resistance ≥95% and a maximum service temperature of 1300℃. Their compressive strength ≥60MPa ensures resistance to minor mechanical impacts from charging materials, while their moderate porosity (≤20%) balances insulation and structural stability.

This targeted application of magnesia composite bricks in the lower shaft prevents slag-induced degradation from spreading upward, protecting the entire shaft lining and reducing overall refractory replacement costs.

Throat & Stack (Low-Temp Abrasion Zone)

The throat and stack operate at 400℃-800℃, with challenges limited to ore/coke charging abrasion and flue gas corrosion. Due to the low temperature and minimal slag exposure, magnesia bricks are not required here—clay bricks and low-alumina bricks (Al₂O₃ 40-50%) provide cost-effective wear resistance without the need for high-purity magnesia. This clear adaptation boundary ensures optimal resource allocation, reserving high-performance magnesia bricks for zones where their properties deliver the greatest value.

Magnesia Brick Supply Details

We specialize in supplying three types of magnesia-based bricks tailored to blast furnace requirements, with flexible specifications, competitive pricing, and global logistics support to meet bulk procurement needs.

Magnesia Brick Specifications for Blast Furnace

Our magnesia brick range is engineered to match distinct blast furnace zones, with customizable sizes and performance metrics:

• Type 1: High-Purity Magnesia Brick (Hearth/Bottom Application): MgO ≥95%, maximum service temperature 1750℃, apparent porosity ≤16%, compressive strength ≥75MPa. Standard size: 230×114×65mm; custom sizes available (230×114×76mm, 250×125×65mm) to fit unique furnace designs.

• Type 2: Ordinary Magnesia Brick (Shaft Lower Application): MgO ≥90%, maximum service temperature 1700℃, apparent porosity ≤18%, compressive strength ≥70MPa. Standard sizes: 230×114×65mm, 200×100×50mm; compatible with most mid-temperature high-corrosion zones.

• Type 3: Magnesia-Alumina Spinel Brick (Bosh/Belly Application): MgO 15-25% + Al₂O₃ 70-80%, maximum service temperature 1650℃, thermal shock cycles ≥35 times, wear resistance ≥95%. Standard size: 230×114×65mm; custom shapes (wedge, arc) available for curved furnace walls.

All magnesia bricks meet ASTM C155 and ISO 8895 standards, with third-party test reports (SGS, TÜV) available upon request to verify performance.

Pricing & Bulk Supply Policy

We offer transparent, competitive pricing for bulk buyers, with tiered discounts based on order quantity and contract duration:

• Type 1 (High-Purity Magnesia Brick): $6.5-$8.0 per piece; bulk order ≥1000 pieces: $5.8-$7.2 per piece.

• Type 2 (Ordinary Magnesia Brick): $4.0-$5.5 per piece; bulk order ≥1000 pieces: $3.6-$4.9 per piece.

• Type 3 (Magnesia-Alumina Spinel Brick): $8.0-$10.5 per piece; bulk order ≥1000 pieces: $7.2-$9.5 per piece.

Additional discounts apply to large-scale orders: ≥5000 pieces receive a 10% extra discount, while long-term supply contracts (≥1 year) qualify for a 15% discount and priority production scheduling. Minimum order quantity (MOQ) is 500 pieces for standard sizes and 1000 pieces for custom sizes.

Packaging & Logistics

To ensure product integrity during transportation, we use moisture-proof packaging: standard packaging includes 200 pieces per pack (moisture-proof plastic film + wooden pallet), with custom waterproof packaging available for sea shipping to prevent humidity damage.

We provide global supply to major ports, including Shanghai, Ningbo, Rotterdam, Houston, and Singapore. Delivery time: 7-15 days for bulk orders (production + shipping); 3-5 days for sample orders (express delivery). Free shipping is offered for orders ≥10,000 pieces to major ports in Asia, Europe, and North America; shipping costs for other regions are quoted based on destination and order volume.

Selection Guide for Blast Furnace Magnesia Bricks

Selecting the right magnesia brick requires aligning performance with zone-specific conditions—follow these key steps to ensure optimal compatibility and value:

Step 1: Match Magnesia Brick to Blast Furnace Zone

• Hearth/Bottom (high temperature, molten iron/slag erosion): Choose Type 1 high-purity magnesia brick (MgO ≥95%) for maximum corrosion resistance. Pair with carbon bricks for comprehensive protection against iron seepage.

• Bosh/Belly (thermal shock, high wear): Opt for Type 3 magnesia-alumina spinel brick, which balances thermal shock stability and wear resistance—critical for zones with frequent temperature fluctuations and charging impact.

• Shaft Lower (mid-temperature, moderate slag erosion): Type 2 ordinary magnesia brick (MgO ≥90%) offers cost-effective corrosion resistance without overengineering.

The selection logic hinges on prioritizing properties: high-temperature/high-slag zones demand high MgO content, while thermal shock-prone zones require spinel-enhanced thermal stability.

Step 2: Confirm Magnesia Brick Specifications

• MgO Content: Determine based on slag alkalinity—highly alkaline slag (common in ironmaking) requires MgO ≥90% (Type 1/2) to form a protective reaction layer; moderate slag can use Type 3 magnesia-alumina spinel brick.

• Size & Shape: Standard sizes (230×114×65mm) fit most blast furnaces, but custom sizes/shapes (wedge, arc) are recommended for curved zones (e.g., bosh) to ensure seamless lining.

• Porosity: For hearth/bottom (molten iron contact), select porosity ≤16% (Type 1) to minimize iron penetration; for bosh/shaft, porosity ≤18% (Type 2/3) balances insulation and structural strength.

Bulk buyers are encouraged to request pre-production samples to test performance (erosion resistance, compressive strength) before placing full orders—we provide free samples for orders ≥1000 pieces.

Procurement & Contact

Our streamlined procurement process ensures efficiency and transparency for bulk buyers, from inquiry to after-sales support:

1. Inquiry: Provide details including blast furnace zone, required magnesia brick type (Type 1/2/3), quantity, size (standard/custom), and destination port—this helps us generate an accurate quotation.

2. Quotation: We respond within 24 hours with a detailed quote, including unit price, total cost, discount eligibility, production timeline, and shipping details.

3. Sample Confirmation (Optional): Request free samples to verify performance; sample delivery takes 3-5 days.

4. Order Placement: Confirm the quote and sign the supply contract; a 30% advance payment initiates production.

5. Production & Inspection: Production takes 7-10 days for standard orders; each batch undergoes quality inspection (porosity, strength, MgO content) with test reports provided.

6. Delivery: Balance payment triggers shipping; we provide tracking information and assist with customs clearance for international orders.

7. After-Sales Follow-Up: Our technical team offers free consultation on magnesia brick installation, storage, and maintenance to maximize service life.

To get a detailed quotation for magnesia bricks used in blast furnaces, confirm supply capacity, or customize specifications, contact our sales team directly via email or WhatsApp with your specific requirements. We also offer value-added services, including custom packaging for long-distance transportation and on-site technical guidance for large-scale projects.

Conclusion

Supplying high-quality magnesia bricks for blast furnaces is our core focus—we deliver tailored solutions that balance performance, cost, and reliability. From high-purity magnesia bricks for hearth/bottom zones to magnesia-alumina spinel bricks for bosh/belly wear zones, our products meet the rigorous demands of ironmaking, backed by global supply capacity and competitive pricing.

By aligning magnesia brick specifications with blast furnace zone conditions, we help clients extend furnace service life, reduce maintenance costs, and ensure continuous production. With ASTM/ISO certification, third-party performance verification, and flexible procurement terms, we are your trusted partner for blast furnace refractory solutions.

Contact us today to streamline your magnesia brick procurement and elevate your blast furnace performance.