No abstract

Primary battery recycling has important environmental and economic benefits. According to battery sales worldwide, the most used battery type is alkaline batteries with 75% of market share due to having a higher performance than other primary batteries such as Zn–MnO2. In this study, carbothermal reduction for zinc oxide from battery waste was completed for both vacuum and Ar atmospheres. Thermodynamic data are evaluated for vacuum and Ar atmosphere reduction reactions and results for Zn reduction/evaporation are compared via the FactSage program. Zn vapor and manganese oxide were obtained as products. Zn vapor was re-oxidized in end products; manganese monoxide and steel container of batteries are evaluated as ferromanganese raw material. Effects of carbon source, vacuum, temperature and time were studied. The results show a recovery of 95.1% Zn by implementing a product at 1150 °C for 1 h without using the vacuum. The residues were characterized by Atomic Absorption Spectrometer (AAS) and X-ray Diffraction (XRD) methods.

The effect of isothermal heat treatments (1 hour at 200, 400, 600 and 800°C) on mechanical properties of thermo-mechanically rolled S700MC steel has been investigated by extensive mechanical characterizations. Treatments at 600°C increase yield and tensile strength and decrease impact energy. Below 600°C the steel retains its bainitic structure. Precipitation kinetics simulations indicate that this secondary hardening effect arises from the nucleation of fine (Nb,Ti)C particles, indicating that the bainitic structure is unstable above 600°C due to its high supersaturation with respect to C, Nb and Ti. These results can help to optimize the operating practices for post-weld heat treatments.

This study was aimed to produce ferromanganese by using waste battery as manganese source, mill scale as iron source and waste coffee ground as reduction agent and carbon source. Waste batteries were collected from waste battery collection bins. Mill scale was collected from hot rolling workshop. Waste coffee grounds were household used coffee. All starting materials were characterized. Weighted raw materials blended with addition of bentonite as a binder. Pelletizing equipment was used to produce composite pellets. Produced pellets were dried then used for reduction experiments. Reduction experiments were conducted in Argon purged tube furnace for 1250 oC, 1300 oC and 1400 oC according to thermodynamic background. Produced ferromanganese samples were characterized for chemical compositions and metallization rate.

One of the promising methods of increasing surface hardness of engineering tools is boronizing. The boronized parts have extreme hardness exceeding 2000 HV, excellent mechanical properties and corrosion resistance. In this study, salt bath boronizing processes were performed on EN-C35E steel substrate in slurry salt bath containing borax, boric acid as boron sources and ferro-silicon as reductant. The process was performed at the temperature of 850º and 950ºC for 2, 4, 6 and 8 hours. Boride layers were examined by optical microscope (OM), scanning electron microscope (SEM) and X-ray diffraction (XRD). Mechanical properties of boride layer were characterized with hardness and fracture toughness measurement. Boride layer hardness was measured by knoop indenter under load of 0,5N and fracture toughness of borided surfaces for 950 °C was measured using Vickers indenters with a load of 4N. Metallographic and XRD analysis revealed that single-type Fe 2 B layers were formed on the surface of EN-C35E steel. Depending on boronizing time and temperature, it was found that the hardness of boride layer ranged from 1895-2143 HK 0.05 that is nearly 8 times higher than the steel substrate hardness. It was observed that the fracture toughness of boride layer ranged from 3.60 to 4.20 MPa m 1/2 .