Calculation of production balances and costs in ladle furnace refining process with addition of scrap steel

Abstract

As increasing the scrap steel ratio has become an important approach for energy conservation and emission reduction in the steel industry, the technology of multi-point scrap addition has emerged. Ladle furnace (LF) refining is a feasible step for scrap steel utilisation, which is often overlooked and relied solely on empirical adjustment, resulting in difficulty of precise control. It is necessary to conduct in-depth research on this process using scientific methods and explore the impact of scrap steel addition on other materials. A comprehensive calculation model was established by scientifically investigating material and thermal balances in the LF process in this article, and the impact of initial steel and scrap compositions, temperature, mass and price of scrap on production costs were analysed and compared based on the model. The results showed that as the carbon and silicon content in the initial steel increase by every 0.01% could on average reduce the production cost per ton of steel by 4.013 CNY and 0.8473 CNY, respectively, and increases by 0.123 CNY as the sulphur content increase every 0.001%. The impact of scrap composition on costs is similar to that of the initial molten steel. Increasing the carbon and sulphur content in scrap by every 0.01% will on average increase costs by 0.0765 CNY and 0.01 CNY, respectively. When the price difference between scrap and the crude steel price is within 450–500 CNY/t, increasing scrap addition will create more profit. The relative reduction in smelting time is 7.97 s as the scrap temperature increases every 50°C. The present study holds academic and industrial significance in improving LF efficiency and promoting the LF process towards a more sustainable direction.