introduction
Magnesia-iron spinel brick is a type of chromium-free refractory brick, resulting in minimal environmental pollution. It possesses excellent thermal shock stability, good kiln coating adhesion, very good erosion resistance, low thermal conductivity and thermal expansion, as well as good structural flexibility.
The low coefficient of thermal expansion and low thermal conductivity distinguish magnesia-iron spinel bricks from other types of bricks. The low thermal expansion coefficient not only protects the lining by reducing thermal stress on the kiln shell but also minimizes damage to both the refractory material and the kiln itself. Low thermal conductivity helps lower the surface temperature of the kiln shell and significantly reduces the thickness of the kiln lining.
Magnesia-iron spinel exhibits excellent structural flexibility, which is attributed to its mineral composition, microstructure, and activation behavior that produces tiny cracks. This structural flexibility reduces damage caused by mechanical stresses generated by kiln shell deformation, thereby extending service life.
Magnesia-iron spinel bricks are primarily made from high-purity magnesite and alumina-iron spinel sand. By optimizing the mix, applying high-pressure forming, and strictly controlling firing temperature and duration, these bricks demonstrate excellent flexibility and thermal shock stability. In the calcining zone of cement kilns, refractory linings must provide both good erosion resistance and high-temperature strength while relying on kiln coating protection for long service life. Without this protection, the lifespan of lining bricks is significantly reduced.
Advantage
1. High purity raw materials:
More than 97% electrofused magnesium sand and synthetic Fe-Al spinel (Fe₂O₃-Al₂O₃) are selected, with impurity content below 0.5%, ensuring material stability at high temperatures.
2. Excellent anti-erosion:
Outstanding resistance to alkali vapor, slag, and metal infiltration; apparent porosity <3.5%; service life 2–3 times longer than traditional materials.
3. Environmental protection without chromium:
Chromium-free formulation with heavy metal leaching rate <0.01 mg/L, meeting EU REACH and national environmental standards.
4. Utilization of renewable resources:
Incorporates industrial waste residues (such as steel slag) as recycled aggregates, reducing the production carbon footprint by over 15%.
5. Thermal performance optimization:
Apparent porosity <3.5% reduces slag penetration; thermal conductivity as low as 1.8 W/(m·K) minimizes heat loss from the kiln.
Zinfon Refractory Technology Co.,Ltd.
We provide one-stop services from technical consultation to design, production, and after-sales support.
Raw Materials
✅ High purity magnesium sand selection:
Over 97% electrofused magnesium sand (MgO ≥ 97%), impurities removed by magnetic separation, finely ground to below 200 mesh for stable chemical composition.
✅ Synthetic Fe-Al Spinel Aggregate:
Synthetic Fe₂O₃-Al₂O₃ spinel produced by high-temperature sintering (Fe/Al ratio optimized), particle size 0.5–3 mm, impurity content <0.5%.
✅ Environmentally friendly recycled aggregate addition:
10%–15% steel slag or industrial waste slag activated by high-temperature calcination to reduce carbon footprint and improve thermal shock resistance.
Physical and Chemical Specifications
|
Type |
MFJ-85A |
MFJ-85B |
|
MgO % |
85 |
85 |
|
Al2O3 % |
3-5 |
4-7 |
|
Fe2O3 % |
4-6 |
3-5 |
|
SiO2 % |
1.5 |
1.8 |
|
Bulk Density (g/cm3) > |
2.98 |
2.96 |
|
Apparent Porosity(%) ≤ |
16 |
16 |
|
Cold Crushing Strength (Mpa) > |
65 |
65 |
|
Refractoriness Under Load (T6.0,9) > |
1700 |
1700 |
|
Thermal Shock Resistance (950℃-Air Cooling) (times) > |
100 |
90 |
|
Thermal Conductivity (W/m.K) |
2.6 |
2.6 |
|
Thermal Expansion (1400℃) % |
1.6 |
1.6 |
process
1.Dosing and Mixing
Precise proportioning: magnesium sand : spinel : binder = 70% : 25% : 5% (ratios adjustable per working conditions).
Nano-modified binder: nano phosphate composite binder with 0.5% rare earth oxides (e.g., Y₂O₃) added to enhance low-temperature sintering activity.
Dynamic mixing: fully automatic system mixes for 40 minutes to ensure even dispersion and avoid segregation.
2. Molding and drying
High-pressure molding: formed with 630-ton friction press, pressure ≥ 200 MPa, billet density ≥ 2.9 g/cm³, porosity <3%.
Microwave drying: 24-hour step drying (60°C → 110°C), moisture ≤ 0.5%, preventing cracking common in traditional kiln drying.
3. High temperature sintering
Gradient temperature-controlled sintering at 1600°C:
Low temperature (800–1000°C): eliminates residual stresses
Medium temperature (1200–1400°C): secondary spinel crystallization
High temperature (1550–1600°C): densification sintering
Atmosphere protection: full inert gas (nitrogen) environment to reduce oxidation and lattice defects, protecting the environment.
Application
Cement kiln transition zone and three air ducts: Resistant to alkali cracking and excellent peeling resistance.
Glass furnace pool walls and liquid flow holes: Resists glass liquid scouring with a lifespan exceeding 5 years.
Ladle slag lines and non-ferrous metal smelting furnaces: Steel slag erosion resistance increased by 40%.
Difference between magnesium-iron spinel bricks and magnesium-aluminum spinel bricks
Magnesia-iron spinel and magnesia-aluminum spinel bricks are both important refractory materials used in high-temperature industries such as cement kilns, glass furnaces, and steel metallurgy. Their core differences lie in raw material composition, crystal structure, performance characteristics, and applications.
1.Raw materials and chemical composition
2.Comparison of performance characteristics
3.Comparison of Application Scenarios
4.Preparation process differences
Magnesia-iron spinel bricks:
Sintered by mixing magnesium sand with ferroaluminum spinel (natural or synthetic), with iron sourced from the ferroaluminum spinel in the raw materials.
Magnesia-aluminum spinel bricks:
Produced by a high-temperature reaction of magnesium sand and bauxite to form magnesium aluminum spinel (MA). The process requires precise control of the Al₂O₃/MgO ratio and sintering temperature.
Summary: How to choose?
Choose magnesia-iron spinel bricks if:
High wear resistance and thermal shock resistance are required, and the working environment is dominated by acidic slag erosion (e.g., waste incinerators).
Choose magnesia-aluminum spinel bricks if:
High refractoriness, resistance to acid and alkali slag erosion, and oxidation resistance are key (e.g., cement kiln firing zones, glass furnaces).
Why chooes us?
Our magnesia iron spinel bricks offer high volumetric stability, high load-softening temperature, and superior thermal shock resistance compared to high-quality magnesia-chrome bricks. They also exhibit better kiln coating adhesion and erosion resistance while reacting less with cement clinker and having a lesser impact on kiln coating spalling. Proven in use, they not only have a long lifespan and smooth surface but are also chromium-free, avoiding environmental hazards.
In the production of magnesioferrite bricks under a reducing atmosphere, the iron-aluminum spinel did not exhibit oxidation state changes during the firing process.
01/Customized dimensions and shapes
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Customized Brick Shape
Provide Sample Sheets--Mold Opening & Quotation--Mold Opening & Sample Making--Bulk Production Quotation--Contract Signing--Bulk Production
02/Delivery cycle and logistics
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Sea freight, land freight. Determine the mode of transportation according to the needs
About 30 days, customized products delivery time depends on the actual situation.
03/Customized packaging
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Customize your brand
Logo customization, custom fonts, taglines and messages for packaging, signage, websites or printed materials.
Take your brand to the next level, contact us today to discuss your project!
04/Purchase ZINFON refractory Bricks at Reasonable Prices
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The price of refractory bricks is a known key factor influencing customers' purchasing decisions. Therefore, we offer affordable refractory bricks for sale. Here are several reasons why ZINFON provides refractory bricks at competitive prices:
Factory price
By collaborating with ZINFON, we ensure that customers enjoy the ex-factory price of refractory bricks, reducing costs from middlemen or distributors. This allows customers to obtain the most cost-effective pricing directly from the source.
Low raw material cost
ZINFON is surrounded by abundant mineral resources. With these high-quality materials, customers can obtain products that are both affordable and excellent in performance.
Mass production
ZINFON possesses advanced production equipment and technologies, enabling the factory to achieve economies of scale and reduce unit production costs. Meanwhile, it ensures a continuous supply of high-quality products at preferential prices.
It is worth noting that while price is an important factor, it should not be the sole determinant of your purchasing decision. When buying refractory bricks from ZINFON, quality, reliability, and technical support are equally important considerations.
By choosing ZINFON as your supplier, you can access high-quality refractory bricks, a wide range of other refractory materials, and comprehensive support. Contact ZINFON Refractories immediately to discuss your specific requirements and obtain customized solutions!
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Provide professional after-sales protection
Our address
Qinghua Management Dist., Dashiqiao City, Yingkou City, Liaoning, China
Phone Number
+8613700131695
+8618540210631
info@zinfon-refractory.com
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