Analysis of bath smelting processes for producing iron

Abstract

A simulation model on bath smelting processes for the production of iron was developed which predicts the coal, flux, ore, and oxygen consumptions and the off gas volume, temperature and composition. The model is comprehensive in that it takes into account all of the important variables including coal composition, metal composition, ore composition, slag basicity, post combustion ratio, (PCR), prereduction degree (PRD), heat transfer coefficient (HTC), flux, scrap charge, and heat losses. Four basic cases were considered: I. 30% PRD–50% PCR; II. 90% PRD–0% PCR; III. 60% PRD–30% PCR; and IV. 0% PRD–50% PCR. Several different coals were considered and a sensitivity analysis of the critical variables was performed. The model also estimates the sulfur content of the metal. The major conclusions are: Post combustion siginificantly reduces coal consumption but above 20% PCR little reduction of FeO to Fe can be performed with the off gas. Prereducing to FeO (case I) and having as much post combustion as consistent with good heat transfer is an attractive process. This process only requires a simple prereducer, uses less coal, and is relatively insensitive to the type of coal used. High off‐gas temperatures may pose a potential problem. The off‐gas temperature can be reduced by using an O2–air mixture for post combustion, limiting post combustion or adding water to the gas. The use of CaCO3 in place of CaO or of supplemental electricity does not appear attractive. The melting unit is theoretically an energy efficient scrap melter. For case I using 200 kg of scrap as part of the charge the coal consumption decreases by about 80 kg. With PCR > 30% the FeO content of the slag is expected to be 2–5%, and the metal will not be saturated with carbon. These factors and the increased sulfur load since coal is the fuel indicate the sulfur content of the metal may exceed 0.25%.

Evaluation of the reduction of iron oxide from liquid slags using a graphite rotating disk

“…[28] Figure 4, a correlalayer, ␦. [26] tion is visible between the reduction rate and the Ίm paramej i ϭ 0.62 и D 2/3 и v Ϫ1/6 и 1/2 и cЊ [1] ter within a relatively wide range of rotations from 0 to 1200 rev/min (Ίm ϭ 4.47), except for the reduction from the ␦ ϭ 1.61 и D 1/3 и v 1/6 и Ϫ1/2 [2] 0.66 basicity slag, where the correlation occurs with the rotations of up to 800 rev/min (Ίm ϭ 3.65). Above these where rotations, a decrease in the reduction rate follows.…”

“…pletely new technologies but also from the complexity of the processes involved. In the proposed reduction smelting process, [1][2][3][4][5] the concentration of physicochemical phenom-II. EXPERIMENTAL ena increases the number of interacting variable factors, thereby, making the evaluation of those phenomena difficult FeO reduction tests were conducted in the ternary CaOin terms of possible complex thermodynamic equilibria and FeO-SiO 2 slag system at temperatures of 1350 ЊC and 1420 also the kinetic aspects of those processes.…”

Reaction mechanism on the smelting reduction of iron ore by solid carbon

“…Therefore, assuming the total pressure (P T ) in the reactor is 1 atm, the flux of CO can be described as in Eq. [1], where P CO is partial pressure of the CO gas in the off-gas and J CO and J Ar are the fluxes of CO and Ar gas, respectively.…”

“…They also may have a higher productivity per unit volume than a blast furnace, and the capital cost seems to be significantly lower than the current process. [1,2] Until now, the corex process was the most fully developed process, producing 300,000 tons of pig iron annually without any problems. In this process, coal is charged into the melter-gasifier and is combusted to CO and H 2 to produce the heat to melt the iron pellets.…”

Contributions by Japanese Researchers at Carnegie Mellon University

“…Whereas all groups developed energy and materials balance models, Fruehan, Ito and Ozturk 7) published an analysis of the process. For example, they showed the effect of post combustion on the coal consumption shown in Fig.…”