Careful Control of Refractory Lining Conditions at NTMK-EVRAZ Ensures Intensive Operation and Long Campaign of Titania Blast Furnace
Nizhniy Tagil Iron & Steel Works, Russia (NTMK) is an integrated Iron & Steel plant, which incorporates cokemaking, blast furnace operation, BOF steelmaking, rolling and other auxiliary processes. NTMK’s metallic burden base is Kachkanar titania-magnetite ore which also contains vanadium. NTMK is a part of the EVRAZ metallurgical holding of Russia and is located in the city of Nizhniy Tagil.
Specific of blast furnace operation producing vanadium containing hot metal is the presence of titania in the burden. Titanium’s solubility in hot metal is limited, and thus various titanium-refractory compounds and titanium oxides are formed in the furnace hearth during the production process. Under conventional operating practice of blast furnace, titanium nitrides and titanium carbides increase the melt viscosity, melt residence time in a reducing atmosphere and as a result increase losses of metal to slag, deterioration of the hearth operation, problem with metal and slag tapping and damage of tuyeres.
NTMK has more than 40 year experience in processing titania-magnetite ore and production of vanadium containing hot metal allowed the development of the major principles of effective blast furnace operation with high titania load [1-2]:
- Optimization of the blast furnace profile by increase in the ratio between height and diameter of the furnace hearth
- Maximum possible increase in furnace pressure
- Optimization of the burden charging procedure by implementing preliminary mixing of metallic burden materials and fluxes
- Optimization of slag basicity to minimize sulphur in hot metal and build an accretion
- Usage of high CSR and large diameter coke
- Minimization of melt residence time in high temperature zone
- Operation of blast furnace with reduced RAFT and hot metal temperature
- Addition of manganese ore to destruct titanium carbides
- Rigid rules of hearth’s thermal condition
- Rigid tapping schedule