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Öğe An investigation of the relationship between compressive strength and dust generation potential of magnetite pellets(ELSEVIER SCIENCE BV, 2013) Sivrikaya, O.; Arol, A. I.Iron ore pellets should have sufficient mechanical strengths against degradation at all stages of pellet production in pelletizing plants. Besides the strength, pellets should have less dust emission during operation since the process efficiency and the pelletizing equipments are adversely affected by dust. Dust is also a problem for sintered (product) pellets since they abrade during transportation from pellet production site to the reduction facilities. Sufficient mechanical strength and low dust emission of pellets are necessary for better operation and handling of pellets. In this study, dust emission mechanism of sintered magnetite pellets produced with different binders was comparatively studied. The results showed that the dust is not produced by pellet breakdown for sintered pellets with sufficient strength. It was found that dust generation of sintered pellets is not directly dependent on the mechanical strength. One of the dust generation mechanisms of sintered pellets with sufficient strength is the roughness of pellet surfaces. The attrition and impact forces during transportation cause dust generation from pellet surfaces. The surface smoothness is more important since the pellets with high strength and rough surfaces produced more dust than those with smooth surfaces and low strength. Half of the fines generated due to pellet attrition or impact forces during handling of sintered pellets will become airborne and are considered as loss and operational/environmental problem. The percentage of particulate matter (PM10) which is significant in health risk lied between 30% and 40% by weight of airborne pellet dust. (C) 2013 Elsevier B.V. All rights reserved.Öğe Method to improve preheated and fired strengths of haematite pellets using boron compounds with organic binders(MANEY PUBLISHING, 2013) Sivrikaya, O.; Arol, A. I.Organic binders as alternatives to bentonite in iron ore pelletisation have found limited application since they fail to give enough mechanical strength to preheated and fired pellets. This paper describes the use of alternative binders to bentonite for haematite ore pelletisation. Organic binders (carboxyl methyl cellulose, corn starch, dextrin) and agglomeration aid chemicals (polymer and flocculants) and boron compounds (colemanite and borax pentahydrate) were tested as binder alone or in combination. The influence of the boron compound added organic binders on the preheated and fired pellet strengths was determined. The results showed that the compressive strengths of preheated pellets at 1000 degrees C made with organic binders can be improved with the addition of colemanite. The compressive strengths of fired pellets at 1300 degrees C produced with organic binders plus colemanite were found to be significantly greater than those of pellets bonded with the reference bentonite binder.Öğe Pelletization of magnetite ore with colemanite added organic binders(ELSEVIER SCIENCE SA, 2011) Sivrikaya, O.; Arol, A. I.A new generation binder consisting of an organic binder and a borate salt was tested as an alternative to bentonite in magnetite ore pelletization. Carboxyl methyl cellulose (CMC),Ciba DPEP06-0007 and corn starch, and calcined colemanite were used as organic binders and the borate salt, respectively. They were added to the pellet feed separately and in different combinations at several addition levels. It was found that the use of organic binders is sufficient in terms of wet pellet quality; however, they fail to render the required compressive strength to pre-heated and fired pellets. Therefore, organic binders and calcined colemanite were used together so that wet pellets, pre-heated and fired pellets would be of the required quality. The results showed that the use of an organic binder together with calcined colemanite indeed yielded pellets with equal or better wet and indurated pellet qualities compared to the pellets produced with bentonite binder alone. (C) 2011 Elsevier B.V. All rights reserved.Öğe Statistical Modeling of Spontaneous Coal Combustion Due to the Effect of the Sun's Rays(TAYLOR & FRANCIS INC, 2015) Ozdeniz, A. H.; Sivrikaya, O.; Kelebek, S.Spontaneous combustion occurs in stockpiles in coal managements and causes interruptions in production and economical and environmental problems. This work was performed on an industrial-scale stockpile formed with +18-mm clean coal. The temperature changes of the stockpile exposed to sun's rays were measured. Concurrently, the values of solar intensity, air temperature, air pressure, air humidity, wind speed, and wind direction affecting the stockpile were measured continuously. A statistical model to predict spontaneous combustion was developed by multi-nonlinear-regression analyses. The correlation coefficients were calculated around 0.95 levels. With this model, the effects of atmospheric conditions on spontaneous combustion of coal stockpiles can be predicted.
