In this study, we evaluated the effects of acid leaching on the properties of Cr powder synthesized using self-propagating high-temperature synthesis (SHS). Cr powder was synthesized from a mixture of Cr2O3 and magnesium (Mg) powders using the SHS Process, and the byproducts after the reaction were removed using acid leaching. The properties of the recovered Cr powder were analyzed via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), particle size analysis (PSA), and oxygen content analysis. The results show that perfect selective leaching of Cr is challenging because of various factors such as incomplete reaction, reaction kinetics, the presence of impurities, and incompatibility between the acid and metal mixture. Therefore, this study provides essential information on the properties under acidic conditions during the production of high-quality Cr powder using a self-propagating high-temperature synthesis method.

This study was conducted to evaluate the microbial contamination levels in the processing company of Nuroong-ji. Microbial contamination levels were examined for sanitary indication bacteria such as aerobic plate count, coliforms and fungi, and pathogenic bacteria such as Escherchia coli O157:H7, Salmonella spp., Staphylococcus aureus, and Listeria monocytogenes. Contamination levels were detected differently according to handling materials and purposing work-space. The equipments and raw materials were not seriously contaminated but there were necessary to attend the cross-contamination. A high contamination level was detected at the process where the interference of the employees was relatively higher than the other process. Standardization of the roasting process (120~170℃, about 10 min) could be necessary to control the microbial organism effectively on Nuroong-ji manufacturing process. At small/medium size foodstuff manufacturers, it is the most important to improve the recognition level of individual hygiene but also expand a hygiene facility.