Study of hot briquetted iron secondary oxidation speed aimed at forecasting of its metallurgical value retention duration

Hot briquetted iron (HBI), as also metallized pellets, undergo oxidation during transportation and storing. To forecast acceptable duration of HBI storing with metallurgical value retention it is important to have scientifically based data on the briquettes secondary oxidation speed. Methods of determining metallized pellets secondary oxidation speed are presented in domestic and foreign practice, but the matter of HBI secondary oxidation in scientific and technicalliterature practically is not covered. To determine HBI secondary oxidation speed two methods elaborated and tested at the Department of metallurgy and metal science of Stary Oskol Technological Institute after A.A. Ugarov (branch of National Research Technological University “MISiS”). The first– weighting method – based on determining of metal iron content change in HBI during a long term storing. During the experiment the mass of each briquette was weighted every 12 h within a month. The result of metal iron content determining by the experiment and by a chemical analysis had a difference of less than 1%. The weighting method enables to obtain the HBI reaction ability values without particular expenses, but requires carrying out long term enough experiments untilcomplete moisture removal out of the studied samples. The other method – determination of oxygen absorption speed bybriquettes in a closed vessel. It enables determining the reaction ability of the reduced iron within a comparatively short period, enables sufficient reliability duringthe briquettes testing. Based on it a methodology elaborated for determining of HBI secondary oxidation speed, meeting the requirements of real production. During loading-unloading operations, briquettes can partially go to ruin. The forming fragments of different sizes undergo a higher degree of oxidation that decreases the HBI metallurgical value. In view of this, studies of HBI oxidation speed continue depending on different sizes content and finalization of the methodology of determination of HBI secondary oxidation speed.