The aim of this study was to investigate the oxidation kinetics of copper at low temperatures (60 °C to 100 °C) in air by isothermal thermogravimetric analysis (TGA) and quartz crystal microbalance (QCM). The weight change in thermogravimetric tests showed periodic weight increase and decrease. In thermogravimetric tests the mass of the copper sample increased until the oxidation gradually slowed down and finally started to decrease due to cracking and spalling of the oxide formed on the surface. In QCM tests using electrodeposited copper film, the weight change was rapid at the beginning but slowed to a linear relationship after few minutes. Temperature and exposure time appeared to have a large effect on oxide film thickness and composition. With QCM, oxidation at 60–80 °C produced less than 40 nm films in 10 days. Oxidation at 90–100 °C produced 40 nm thick films in a day and over 100 nm films in a week. Although SEM-EDS analyses in TGA tests indicated that oxygen was adsorbed on the copper surface, neither XRD patterns nor Raman spectroscopy measurements showed any trace of Cu₂O or CuO formation on the copper surface. Electrochemical reduction analysis of oxidized massive copper samples indicated that the oxide film is mostly Cu₂O, and CuO develops only after several days at 90–100 °C.

The aim of this work was to explore the effect of mineralogy and gas reductant on the reduction of nickel laterites. Three different nickel saprolitic ores reduced by carbon monoxide were examined, and the results were compared with hydrogen reduction of the same ores. The reduction experiments were carried out in a thermobalance furnace which allows continuous measurement of mass change. The ores were reduced in CO/CO ₂ (72%∶28%) at 750 and 900°C for 90 min. Chemical analysis was utilised to determine the degree of metallisation of the reduced pellets. It was found that the reduction rate and degree of removable oxygen at 750 and 900°C in CO/CO ₂ was lower compared to reduction experiments in H ₂ /N ₂ (72%∶28%). The reducibility of the samples seems to depend on mineralogy and their modes of decomposition and recrystallisation. The results clearly indicate that using various reducing gases has an impact on the reduction behaviour and generation of metallics of nickel saprolitic ores.

Stainless steel production generates significant quantities of flue dusts, which are considered as hazardous waste in most industrialized countries as they contain harmful elements, such as heavy metals. On the other hand, the dusts also contain valuable metals, such as steel alloying elements, but the recovery of the valuables is difficult due to the complex composition of the dusts. In this work, the melting behavior of dusts from an Electric Arc Furnace and an Argon Oxygen Decarburization converter were investigated at temperatures 800-1400 °C. In addition, the interaction between a synthetic dust, with high concentrations of potassium, fluorine and chlorine, and selected refractories was studied at 1300 °C mimicking the freeboard conditions of a dust smelting furnace. Melting of the EAF dusts begun in the temperature region of 1250-1300 °C depending on the composition, whereas AOD flue dust, because of its high fluorine content, had a melt fraction of approximately 30 % already at 1200 °C. The present experiments showed that magnesia has good corrosion resistance against potassium vapors at 1300 °C and the penetration depth of potassium into chromium-containing refractory materials was limited to the vicinity of the contact surface. In addition, alumina-silicate refractories seem to be more susceptible to volume expansion than the other refractories studied, causing cracks through which potassium vapors can easily penetrate deep into the refractory lining.