Byproducts/wastes of iron-and steelmaking processes and steel scrap are the main sources of iron units recycled in the steel plants. Direct recycling of the iron oxide wastes (dusts and sludge) in the blast furnace (BF) is however hampered by its chemistry (.0 . 1%Zn in the charge). Vaporisation, condensation, oxidation and circulation of zinc may collectively lead to the accumulation in the furnace. Very fine particles are deposited on other particles that have high surface areas which diminish BF refractory life and impair the quality of high quality pig iron produced. For effective continuous recycling of iron units, it is necessary to identify their sources, determine their composition and evolve device and appropriate technology for the treatment of zinc bearing units. The present paper analyses the process of zinc accumulation in the BF and derives an algebraic model to determine the extent of the accumulation. On the basis of analysis of zinc base formation, its recirculation in the furnace and other related productive units, a homograph (alignment chart) of zinc accumulation is designed. The paper also outlines the feasible processes of zinc removal from the close-looped system (sinter plant-BF-sinter plant).
This paper studies the antimicrobial activity of selected engineering materials surfaces at room and chill temperatures. The antimicrobial effects of selected materials surfaces were evaluated by dropping the test pieces into prepared cultures of Bacillus spp, Escherichia coli, and Staphylococcus aereus isolated from fruits, animal feaces and natural environment respectively. Bacteria count obtained after 0, 30, 60, 90, 120, 180, 240 and 300 minutes at room temperature and chill condition was taken and compared with their initial count. The amount of live bacteria drops by several orders of magnitude, to zero, on metallic copper and brass within 30 to 300 minutes in both room and chill conditions. In contrast, no reduction is seen in the number of colonies of live bacteria on plastics, ceramic and stainless steel in both room and chill conditions. These results suggest that the selection of metallic copper and brass for touch surfaces in hospitals, surfaces exposed to fruit processing and household utensils can materially assist in reducing bacterial contamination, which should lead to a reduction in the transmission of infectious organisms.
The use of coconut shell particulates to enhance the insulating refractory properties of Ukpor, Osiele and Kankara fireclays in Nigeria was studied in this paper. The chemical analysis of the raw materials was conducted using Atomic Absorption spectrometer. The samples used for different tests were prepared by mixing the clay, bentonite and coconut shell, of grain sizes of 212 -600 µm. The prepared samples were air and oven dried for 24 hours at room temperature and at 110˚C respectively. The samples were then fired at different temperatures in the range of 950˚C to 1200˚C at 50˚C interval and at 2.5˚C/min. The fired samples were investigated for their physical, insulating (thermal) and mechanical properties. Micro-structural examination was also carried out. The results indicate that clays with 25 wt% -30 wt% coconut shell and grain sizes of 212 -300 µm fired at 1150˚C -1200˚C possess enhanced mechanical, physical and insulating (thermal) properties. The SEM micrograph revealed the formation of mullite phase in the bricks fired at 1150˚C. Thus, high quality refractory bricks with enhanced insulating properties could be produced from Ukpor, Osiele and Kankara fire-clays blended with coconut shell particulates.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.