The evolution of structural order, microstructure and mineral matter of metallurgical coke in a blast furnace: A review

Carbon dissolution from graphite and coals was investigated by using a carburizer cover technique in an induction furnace. The intent of the study was to investigate the influence of factors governing the rate of carbon dissolution from carbonaceous materials, especially coals, into Fe-C-S melts. The factors studied were the initial melt carbon and sulfur concentrations and the wettability between carbonaceous materials and the melt.

Dissolution rates of coals and graphite in Fe-C-S melts in direct ironmaking: Influence of melt carbon and sulfur on carbon dissolution

Interfacial reactions occurring between molten iron and carbonaceous materials are of great significance in the steel industry, and specifically, the reaction of iron with metallurgical coke is one of the key phenomena occurring during blast furnace ironmaking. Major operating parameters such as hot metal composition will be directly influenced by the reactions occurring between liquid iron and coke. In the current investigation, the interfacial reactions occurring between coke and liquid iron were studied at a temperature of 1550 °C using the sessile drop method to further the understanding of the fundamental reactions occurring at the interface between coke and iron. The formation of interfacial reaction products was observed, and time-dependent reactions were identified. The transfer of elements such as carbon, sulfur, and silicon was determined. The reduction of silica was determined as having a major influence on the transfer of both silicon and carbon into liquid iron.

Influence of ash on interfacial reactions between coke and liquid iron

The melting rate of steel bars with various sizes, shapes, and initial temperatures in a 70 kg liquid steel bath (1650 °C) was measured to investigate the kinetics involved in steel scrap melting. Our measurements revealed that a solidified shell was formed around the original bar immediately after it was immersed into the liquid steel. This shell and an associated interfacial gap generated between it and the original bar were found to be critical to the melting kinetics. We also found that the total melting time decreased linearly with increasing initial bar temperature. The melting process was simulated using a two-dimensional phase-field model that considered heat convection with a constant heat-transfer coefficient. Our simulations were in good agreement with our experiments and showed that the heat conduction associated with the interfacial gap was one of the most important physical aspects controlling the melting of steel scrap.

Kinetics of scrap melting in liquid steel

Research on the use of waste polymeric materials is one of the solutions for developing environmentally friendly recycling processes for steelmaking. Different polymeric materials [i.e., rubber, high-density polyethylene (HDPE), polyethylene therephtalate (PET), and Bakelite], which have different chemical structures and compositions, were selected for this study as carbon resources. The rapid heating to high temperatures provided during steelmaking will break down the polymeric chains and reactions with liquid slag, enabling gas formation. The dynamic changes in the volume of the slag droplet while in contact with the coke/polymer substrates are measured. Significant levels of gas generation and entrapment are present, leading to an improved performance over coke. Carbon/metal reactions were studied by measuring carbon and sulfur pick-up by liquid metal as well as the formation of reaction products at the metal/carbon interface. The measured carbon pick-up value after 2 min of reaction for metallurgical ...

Recycling End-of-Life Polymers in an Electric Arc Furnace Steelmaking Process: Fundamentals of Polymer Reactions with Slag and Metal

The dissolution rates of commercial black iron rods in iron/carbon melts under isothermal conditions were measured. The effect of melt carbon content, temperature, natural convection, and gas stirred forced convection conditions were investigated. The experimental data under natural convection conditions (no external stirring) were fitted with a dimensionless correlation for vertical cylinders: Sh = 0.13(Gr . Sc)0.34, representing mass transport control dominated by turbulent natural convection. Under bottom injection gas stirring conditions, it was found that the kinetic power input had little effect on the rod dissolution rates which were controlled by the total gas flow rate. Derived mass transport coefficients under gas stirring conditions were found to have the following dependence on the gas injection rates:k
m ∝Q
0.21, wherek
m = mass transport coefficient andQ = gas flow rate. A comparison of the experimental results with previously measured mass transfer coefficients under forced convection conditions gave a plume velocity flow rate dependence ofU ∝Q
0.3. A general discussion of gas stirring fluid dynamics and resulting mass transport effects is presented.

Steel dissolution in quiescent and gas stirred Fe/C melts

An experimental investigation was undertaken to study the kinetics of graphite dissolution in gasstirred iron/carbon melts. Laboratory apparatus was developed to allow the injection of closely sized graphite into the bottom of a 1 kg scale reactor with nitrogen as a carrier gas. The effects of gas flow, particle loading, particle size, bath sulfur, and temperature on the rate of dissolution were assessed. It was found under the experimental conditions used that the graphite dissolution rate kept pace with the injection rate up to approximately 85 pct of carbon saturation, except when sulfur is present in the bath, in which case the dissolution rate is retarded. Modeling the rate of graphite particle dissolution supports the experimental results in that particle dissolution occurs quickly and under mass transport limitations. Computer generated gas-stirred flow field diagrams for the experimental reactor indicate that conditions exist for particle entrainment in the bath, and hence complete contact with the melt at all times during dissolution.

J. K. Wright

Papers

Steel dissolution in quiescent and gas stirred Fe/C melts

Dissolution kinetics of particulate graphite injected into iron/carbon melts