Direct chromium alloying by chromite ore in EAF operation is a promising process in stainless steel production, which has the advantage of resource-saving, energy-saving, and environment-friendly. In the present investigation, iron, carbon, and chromite ore mixture (Fe+C+FeCr2O4) were chosen as the precursor for direct chromium alloying. Thermogravimetric Analysis (TGA) experiments were carried out to investigate the effect of iron content on the reduction kinetics, and the results show that the presence of metallic iron in the precursor will increase the reduction rate of chromite. Up-scaling experiments (100 g and 500 g scale) have been carried out in the induction furnace to further test the effectiveness of using industrial chromite ore for direct chromium alloying. The induction furnace tests confirmed the necessity of adjusting composition of the slags to ensure high yield of chromium in the final products; and chromium yield can reach 90%.

This work investigates the high temperature behavior of six different quartz types A, B, C, D, F and G during heating to elevated temperatures. These quartz types contain different amounts of impurities, from 1% to 0.1%, and have earlier shown different degree of disintegration during heating. Melting experiments to 1750 °C have been performed to find softening and melting temperatures, and it is found that there are significant variations between the different quartz types. A higher content of impurities lowers the softening and melting temperature. The quartz surface has also been studied during heating to 1600 °C in a high temperature confocal microscope. From this, it is found that disintegration mainly happens at two temperature intervals, ~300–600 °C and ~1300–1600 °C, and is mostly due to volume changes in either the SiO₂ matrix or the impurity areas. The cracks occur from impurity areas, expanding grain boundaries, damaged or uneven SiO₂ surface and in some cases from the cavities from the escaped fluid inclusions.

The advantages of using CO2 for the decarburization of high alloy steels have been recognized from environmental and economic view points. The present paper presents the heat and materials balances in the decarburization process with the introduction of CO2 as a diluting gas in Electric Arc Furnace (EAF) process for steel production. The aim is to optimize the amount of CO2 and the materials requirements, which includes the addition of scrap, hot metal and coolant. These estimations are also important to control the bath temperature, thereby prolong the lifetime of the refractory lining of the furnace. The present calculations enable an optimization of the CO2:O2 ratio and materials input in the decarburization of carbon steel melts. Another important extension of the work is the possibility to enhance the addition of hot metal during steel making process. The present results show that addition of up to 20% hot metal is likely to the energy loss due to the introduction of 50% CO2 for a 110 tons EAF resulting in the saving of electric energy.

To study the final equilibrium state and process of CO₂injecting into the Fe–C melt with different initial carbon contents, a model was established based on the method of minimization of Gibbs free energy and the corresponding experiments were carried out in a high-temperature tube furnace. When CO₂is continuously injected into the Fe–C melt at 1873 K, the final equilibrium state of the system is such that the carbon and oxygen contents in the melt are 0.1977 and 0.0115 wt pct, respectively, and the volume ratio of CO in the gas phase is 85.75 vol pct. When the initiala_[O]×a_[C]in the melt is greater than those in equilibrium with CO under 0.8575 atm, the CO₂gas removes carbon from the melt. On the contrary, the role of CO₂gas is to add carbon and oxygen to the melt. At the same time, the variation of carbon and oxygen with time obtained by experiments was different from the theoretical calculation at extremely low carbon content, which requires further study.