Improvements in Steel Melting Efficiency -- Industrial Trials

Industrial trials were completed to improve energy efficiency in steel melting. First, the benefits of increased chemical energy from an oxyfuel burner and a Co-Jet system in a basic 20 ton electric arc furnace (EAF) were studied. Observations and measurements were made during production before and after the installation of the two systems. The additional chemical energy improved energy efficiency and resulted in increased production. In addition, production using a basic EAF practice was compared to the traditional acid EAF practice. Second, an industrial trial using a 750 lb ladle with a combination of a lightweight alumina castable refractory and a insulating board was compared to a standard alumina castable ladle. The new material also showed a potential for significant energy savings

Using Automated Inclusion Analysis for Casting Process Improvements

Different industrial melting and ladle practices (deoxidation, slag, refractory types, etc.) used in steel foundries were analyzed and compared using an ASPEX automated inclusion analyzer for study of inclusions. The effects of deoxidation and pouring practices on the size, type and number of inclusions were evaluated for steel foundries equipped with induction and arc melting furnaces, with capacities ranging from 1 to 20 tons. Samples were collected from the furnace, ladle, and castings. Specific rules were developed for classification of inclusions by composition, size distribution and shape. Inclusion statistics, including composition, quantity, shape, and size during cast steel processing from the furnace to the final casting were used for treatment optimization in the foundry ladles

Thermal Efficiency of Steel Melting

This paper presents the results of energy consumption measurements at steel foundries using induction and/or electric arc furnace melting. Statistical methods, infrared thermography, and numerical investigations were used for analysis of heat losses. The influence of different melting practices on energy losses was examined. Industrial experiments in isothermal holding of liquid steel in induction furnaces under different power inputs were used for evaluation of the real values of heat losses by radiation from liquid steel and conductivity through lining. Average values and statistical distributions of energy consumptions for melting steel are presented in this article

Simulations of a New Continuous Steelmaking Process

A new continuous steelmaking process has been designed in an effort to reduce meltshop costs and increase productivity beyond the possibilities of current EAF-LMF-CC meltshops. This paper discusses possible operational performance based on industrially-verified kinetic, thermodynamic, and heat-transfer models. Dynamic simulations predict variations in steel chemistry and temperature, resulting from steel treatment and upsets. Savings in costs are projected because of increased metallic yield, lower energy requirements, more efficient use of deoxidants and alloys, fewer man-hours per ton, and decreased capital investment

Increasing Energy Efficiency through Improvements in Ladle Materials and Practices

Steel foundry ladle practices play an important role in total energy efficiency of melting as well as influence casting quality. Extensive heat losses in the ladle could be associated with excessive superheating of the melt before tap which increases energy consumption, promotes oxidation of the melt and increases refractory consumption. A high cooling rate of the liquid metal in the ladle could also cause casting quality instability. The overall ladle heat balance and components of heat losses were analyzed using FLUENT and FACTSAGE software and validated with experimental data from both the UMR foundry and industrial foundries. The purpose of this paper is to study foundry steel ladles with a focus on increasing energy efficiency through the use of novel lining materials and special techniques of decreasing thermal losses. Special low thermal conductivity materials have been proven to decrease the heat losses significantly resulting in an increase in the holding times and allowing tap temperatures to be decreased by up to 200 degrees F, depending on ladle practices. The laboratory experimental data were incorporated into a computer model that predicts conditions in industrial foundry ladles

Efficiency in Steel Melting: Ladle Development

Effective ladle design and use is important for steel casting production. In foundry operations, the ladle temperature of the liquid steel is typically 150 to 250°F above the steel\u27s melting point to compensate for the heat losses in small ladles and the associated high cooling rates from the large surface area to volume ratios. Higher superheat is also necessary to provide sufficient steel fluidity to properly fill the mold cavity. In spite of the relatively short time that the steel is in contact with the ladle lining, the huge thermal gradients in the lining drive high values of heat flow through the refractory surface. Heat transfer between the melt and the ladle lining as well as the associated heat losses in foundry linings are analyzed in this paper. Initial information was taken from a survey of steel foundries and from industrial measurements at seven foundries. Temperature measurements were done with thermocouples and infrared cameras. Fluent software was used for modeling unsteady heat transfer in ladles. The influence of the thermal properties of different ceramic materials typically used for steel ladle linings on heat losses during use was analyzed. A novel class of ladle linings being developed at UMR based on porous ceramics has the potential of significantly decreasing the heat losses during use in addition to saving considerable ladle preheat energy. This paper reviews progress in developing and testing these linings

Alloy Recovery and Control in Steel Melting

Alloy recovery plays an important role in steel melting economics because the cost of alloying additives such as ferroalloys and pure non-ferrous metals is significantly higher than the cost of steel scrap. Recovery of alloying additives also influences the reproducibility of steel properties from heat to heat. This paper reviews alloy recovery and final chemistry distributions at seven steel foundries and preliminary laboratory studies of alloy dissolution in ladles. Melting and alloy practices were observed for several plant trial heats in each of the foundries. Alloying and chemistry data were collected for an additional 20 - 155 heats at each plant. The recovery of alloying additives depends on the type of furnace and individual foundry practices. EAF operations had greater variations in final chemistry performance than induction furnace operations. Laboratory experiments showed that there is a potential for increased alloy recovery and control through argon stirring with a porous plug. Argon stirring decreased mixing time by 50% and decreased the local variation in steel composition

Decreasing Electrical Energy Consumption through SiC Additions

This paper summarizes results of industrial experiments investigating the introduction of supplemental chemical energy in Electric Arc Furnaces (EAF). Specifically, this research evaluates the effects of adding 0.4-0.6% of the scrap charge weight as SiC (10 lbs per scrap ton charged) in the EAF. SiC additions increase the available exothermic reactions during oxygen boiling in an attempt to reduce the electrical energy requirements. Results from 180 trial heats at two different steel foundries are highlighted and statistically evaluated. In both cases, the SiC additions had a measurable effect on decreasing the electrical energy consumption