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Blast furnace repair

Seven offers the most integrated approach to blast furnace repairs.

All around blast furnace repair

Based on a large product portfolio of refractories, Seven offers the most integrated approach to blast furnace repairs.

Facts & Figures

Blast furnaces have been at the core of Seven’s activities right from the start, with more than 60 successfully completed projects world-wide in only 10 years.
The most comprehensive repair to date included the hearth, the shaft, the gas up-takes, and the cyclone.

The fastest repair was performed in only five days with robotic shot-creting, reaching a record speed of more than 14 tons per hour.

The prize for the coldest repair project goes to a blast furnace repair at minus 35 degrees.

Entrust us with your blast furnace repair and let us set a record for you.

Seven Blast Furnace Repair Advantages

  • Total care of the entire repair project:
    Seven combines state-of-the-art material with complete project management. Each project is guided from initial study through all steps of installation. For the repair project, the customer has one single contact interface.
  • Complete blast furnace repair competence with flexible solutions
    • Repair areas from the hearth to the top
    • Partial or total relining
    • Manual and robotic shot-creting
    • Precasted solutions for staves
    • Different technologies of hearth repair
    • Repairs of auxiliary units such as hot blast stoves (cowper) and chimneys, gas cleaning systems with cyclones, scrubbers, and so on.
  • Integrative approach with own teams or in cooperation with other installation companies, own equipment, on world-wide basis.
  • High speed of installation: with short interventions, customers minimize down-time and take the blast furnace back in operation quickly
  • Advanced formulation: careful selection and composition of raw materials and additives.
    Seven develops, produces, and installs tailor-made materials with enhanced resistance to the specific stress factors in the different furnace sections.
    The product portfolio also includes specialties such as silicone carbide-based plastic gunning mixes or chemically bonded grouting masses.
  • Return on investment:
    Speedy installation leads to obvious savings when unnecessary downtime is avoided.
    High-quality and well-planned repairs enables customers to run the furnaces for longer times after the intervention.
    Together with the customer, Seven can redefine the geometry of the furnace to improve the performance efficiency and economic output of the blast furnace.
  • Post-Installation Customer Service: Each intervention can be analyzed to evaluate efficiency and to improve future scheduled and unscheduled interventions in a continuous improvement cycle.


The Modular Hearth Shield (MHS) by Seven Refractories offers products to create a protective long lasting layer for the carbon lining in the blast furnace hearth.

With this concept we offer an ideal geometrical solution based on optimal material quality,  instead of liningfollowing a “just enough” approach.


Carbon lining protection, i.e. contrast the erosion mechanisms given by:

  • Oxidation
  • Corrosion by alkali
  • Disintegration by CO
  • Hot metal and slag penetration
  • Thermal stress
  • Dissolution due to hot metal and slag flow

MHS and Environment: Which connection?

Ready-to-use block shapes prevent hot metal from floating out and the improved heat-transfer to the cooling elements contributes to the formation of a dense protective layer at the MHS surface that preserves the blocks from further consumption, thus enabling them to exploit their proper technical function.

All in all, the MHS solution leads to several years of life expectance and therefore cost savings.

A refractory model designed to optimize the whole of hearth lining, block shapes, quality zoning distribution, thermo-mechanical stresses.


A pre-assembled solution allows:

✔ any geometry of the blocks also in terms of thickness, shapes and quality distribution,

✔ long term solution. Protecting the carbon lining by a “MHS technique” which operate for 5-6 years,

✔ less CO2 emission,

✔ less fuel consumption.


All blocks are engineered on white fused alumina and/or fused alumina – mullite; the ramming is engineered on brown fused alumina – Carbon – SiC; the mortar is engineered on brown fused alumina-bauxite.

Architecture of the Modular Hearth Shield:

  • 4 different product qualities for the blocks
  • 1 ceramic bonded carbon-SiC containing ramming
  • 1 chemically bonded mortar
  • 14 different shapes


Material quality and geometrical solution overcome the concept “preshaped” lining.

  1. Products thermal characteristics enhance the heat transfer to the cooling elements contributing to the forming of a dense hot metal layer at the refractory surface contact added
  2. Several years life expectancy is the result of the lining architecture, the dedicated material developed and the accurate manufacture of the blocks.
  3. The concept of Seven Refractories is an economically attractive and increases the safety and life of the hearth with a limited investment.