Table of Contents

    • 44

    • A CFD Study of Alloy Dissolution and Homogenization in Ladle Metallurgy Furnace

      The addition of microalloying elements in steel production is essential to improve steel properties, as they have a strengthening effect even in small amounts. The dissolution process of copper in the ladle metallurgy furnace was studied using parametric tests on the number of plugs and argon gas flowrates for stirring. To understand the particle movement in the molten bath, numerical simulations were performed using a three-dimensional computational fluid dynamics method. The results show that the mixing time is affected by the number of plugs and the gas flowrate, with the shortest mixing time achieved with a single-plug ladle with a flowrate of 0.85 m3/minute and a dual-plug ladle with a total flowrate of 1.13 m3/minute, both taking 5.6 minutes.

    • 50

    • Challenges for the Refractory Industry to Support the Foreseen Large-Scale Transition to DRI Shaft Kilns

      The global commitment to carbon neutrality by 2050 is a major challenge for society as a whole and steel plants in particular. Engineers at steel companies and original equipment manufacturers are working hard to understand how to tackle this challenge. The direct reduced iron (DRI) process is considered a logical replacement for the reduction task of the blast furnace, since it allows up to 38% carbon dioxide (CO2) reduction using methane (CH4) and up to 80% CO2 reduction using hydrogen (H2). A shared concern is the availability of quality iron ore and green hydrogen. This article addresses the challenges for refractory producers as the operating conditions most likely will change with possible effects on the current lining arrangement. A deeper understanding of these conditions would help achieve an optimum refractory lining concept for future DRI units.

    • 58

    • Use of CaO-Al2O3 Synthetic Slag on EAF Tapping for Steel Desulfurization

      Steel desulfurization is usually performed by CaO-Al2O3-based top slags. However, in the steelmaking process at a steel mill in the city of Cariacica, ES, Brazil, deoxidation is carried out on tapping with the addition of ferrosilicon-manganese and silicon carbide, and desulfurization is carried out in the ladle furnace with the addition of lime and calcium carbide. The present work aims to change this process by adding a CaO-Al2O3 system slag during the electric arc furnace (EAF) steel tapping, so that the desulfurization occurs already in this step, thus enabling CaC2 economy in the ladle furnace. Three lime/alumina briquette ratios were determined, where the CaO activity, liquid slag ratio and viscosity were analyzed. Then, the desulfurization yields of these heats were compared to the conventional route. The influence of additions and of the slag carryover on desulfurization efficiency was analyzed by correlation charts and a mathematical model developed. It was found that the slag carryover from the EAF impairs the desulfurization, causing sulfur reversion from tapping until the ladle furnace arrival, and decreasing the desulfurization rate on the ladle furnace treatment by promoting high-equilibrium sulfur content, close to the real reached value. The most efficient slags were the ones with the greatest calcium oxide activities, which is in line with the steel desulfurization factor.

    • 70

    • Distributed Temperature Monitoring of Tundish Refractory Lining Using Optical Fiber Sensors

      Distributed temperature monitoring can provide useful insights into thermal conditions in the continuous caster tundish that can affect operating stability and cast quality, such as pre-heat conditions, superheat uniformity, fill height and refractory wear. In the current study, fiber-optic sensors were embedded into the refractory lining of a lab-scale tundish to record the temperature profiles during dry-out, pre-heating and direct molten steel exposure to demonstrate sensor performance. Additional trials were performed with fiber-optic sensors embedded in an industrial tundish used in production. The results demonstrate that fiber-optic sensors using Rayleigh technology can provide accurate distributed temperature measurements in refractory-lined vessels and provide useful information about the process.

    • 82

    • Energy-Efficiency Refractory Bricks for Steel Ladle Linings

      Steel ladle lining plays an important role in energy consumption during production, and refractory lining design contributes to minimizing thermal bath loss and shell temperature. A new generation of unfired zero-carbon refractories was developed with two specific approaches: (i) replacement of firing bricks reducing CO2 footprint and (ii) replacement of carbon-containing refractories while increasing performance. Bricks can be used in working and safety linings with a unique microstructure with better heat scattering and similar thermomechanical properties. This work presents customers’ performance compared to traditional products, highlighting energy savings.