Background The steel industry has benefited from the economic benefits of steel fibre reinforced refractories for over two decades. At both integrated and Electric Arc Furnace steel plants there are many refractory applications which benefit form the addition of fibres reinforcement.
Fibretech offers a range of stainless steel fibre alloys to meet the requirements of individual applications including fibres which withstand hot face temperatures of up to 1400-1500°C.
Refractory Trends in the Steel IndustryAs the steel industry moves away from the use of bricks to monolithic refractories the use of stainless steel fibres is ever increasing. Furthermore the growing importance of rapid and safe refractory installation has seen a rise in the use of shotcrete and gunning materials. Fibretech’s melt extract fibres are ductile at room temperature and are therefore used successfully to reinforce sprayed refractories.
Secondary Steel MakingThere are a number of areas in secondary steel making furnaces that can benefit from stainless steel fibre reinforcement. These will be outlined in the following sections.
Figure 1. Areas in secondary steel making furnaces that can benefit from stainless steel fibre reinforcement.
Ladle Vacuum DegassingSnorkel LegsThis refractory lining is exposed to repeated thermal cycling and prolonged exposure to high temperatures, often up to 30 minutes. A fibre-reinforced refractory lasts considerably longer to give significant economies in production and maintenance costs.
Recommendation: ME 446
Sprayed Re-Lining to Snorkel LegsThis interim repair prolongs the overall campaign life of the degasser vessel. By adding fibres further cracking and spalling of the sprayed relining is inhibited and the vessel's campaign life improved still further.
Recommendation: ME 446
Soffit Protective LiningRadiant heat and splashing molten steel often combine to crack and spall this refractory lining. If not stopped, this leads to expensive repairs to vessel steelwork. Fibre addition will hold cracked refractory intact, reducing the risk of these costly repairs.
Recommendation: ME 446
Ladle Furnace RoofDelta SectionIn this important application damaged refractory causes expensive heat loss and repair. ME fibres minimise these costs, particularly in the thin refractory walls between electrodes, denying heat an escape path and keeping energy and production costs down.
Recommendation: ME 446
Ladle Roof LiningProduction costs rise when aggressive slag attack and extreme shock combine to reduce the lining integrity and increase energy loss and maintenance costs. ME fibres hold the lining intact for longer, thereby improving thermal insulation and energy conservation.
Recommendation: ME 446
Ladle UpIntimate contact between the roof and ladle lip is essential to prevent heat loss and minimise production costs. A fibre reinforced lip is more resistant to distortion so even if cracked, heat retention and energy costs are optimised.
Recommendation: ME 446
Ladle BottomImpact PadAs with a tundish impact pad, this suffers repeated thermal shock during its life. ME fibres, at 34% by weight addition can improve performance by 100% or more, reducing downtime and cutting refractory material and installation costs by at least 50%.
Recommendation: ME 446
Nozzle and Purge PlugA fibre-reinforced plug or nozzle has increased service life over other designs. Even when cracked the refractory is held tight, maintaining a more consistent shape thereby improving durability and service life and reducing production costs.
Recommendation: ME 446
Seating and Well BlocksSeating and well blocks for ladle nozzles and porous plugs are expensive consumables. A fibre reinforced block can last as long as the bottom lining, significantly cutting ladle downtime and yielding important savings in energy and maintenance.
Recommendation: ME 446
LadleSecurity LiningWithout fibres movement of the security lining (eg thermal expansion, mechanical shock) can crack the refractory, shorten the lining's working life and increase the risk of hot metal run-through. Fibres reduce both these risks, ensuring a longer ladle compaign, reduced downtime and lower maintenance costs.
Recommendation: ME 446
Ladle Transfer CarSplashing steel and the loading and unloading of the ladle can damage the car's steelwork and refractory lining. A fibre-reinforced lining resists thermal and mechanical shock, avoiding the need for frequent costly repairs.