Utilization of charcoal in the iron-ore sintering process (original) (raw)
Related papers
Combustion and Flame, 2011
A study was carried out into the use of hardwood charcoal as a supplementary fuel in the iron-ore sintering process. The primary fuel was coke breeze with 0%, 20%, 50% and 100% replacement of the energy input with charcoal to produce raw blends with the same heat output as 4.0 wt.% coke breeze. Experimental results indicate that fuel blends where 20% of the heat input was provided by charcoal may improve both the sinter yield and sintering productivity by up to 8%, under normal sintering conditions. In addition, the 20% replacement of coke energy with charcoal would mean that part of the carbon dioxide emitted from the process would be from a renewable source and could be used to offset carbon dioxide emissions from non-renewable fossil fuels. At higher rates of coke breeze energy substitution with charcoal, the lower sintering performance observed was mainly attributed to the lower fixed carbon content and higher volatile matter content of the fuel mix. At the optimum rate of 20% substitution of coke breeze energy input with charcoal, the emission of dioxins were similar to those observed with coke breeze alone as the fuel. However, sintering with 20% energy input from charcoal resulted in a slight increase in middle molecular weight and lower molecular weight PAHs, contributing to a minor increase in B[a]P-eq from 0.15 lg/m 3 to 0.17 lg/m 3. Overall the results from the laboratory scale tests suggest that it is feasible to substitute 20% of the coke breeze energy input with an equivalent amount of energy from charcoal in the iron-ore sintering process.
Substitution of Charcoal for Coke Breeze in Iron Ore Sintering
ISIJ International, 2013
The substitution of charcoal as an alternative fuel to coke breeze in a simulated Japanese Steel Mills (JSM) sinter blend was investigated. Compared with coke breeze, higher mix moisture contents were required for the sinter mixture containing charcoal to achieve optimum granulation. The green granules formed from the sinter mixture containing charcoal were clearly less dense and formed a less compacted green bed as evidenced by the packing density. To achieve return fines balance, fuel addition had to be increased from 3.62 to 4.17% (on a dry mixture basis) as the substitution of charcoal increased from 0 to 50%. However, at 100% subsitution, the sinter mixture failed to achieve balance even at a very high fuel addition level of 4.7%. Compared with the sinter fired with coke breeze, the sinter from the mixtures containing up to 50% charcoal was marginally weaker in terms of sinter yield, tumble strength (TI) and reduction disintegration (RDI). The reasons for weaker sinter are discussed. Fuel rate increased considerably with charcoal substitution due to increased fuel addition and decreased sinter yield. However, increasing fuel rate did not lead to a reduction of sintering productivity. In contrast, the sintering speed and productivity were maintained as the charcoal substitution rate increased from 0 to 25% and then increased considerably with further increase in charcoal substitution rate. The emission mechanisms of the CO, CO2, SO2 and NOX and H2O gases during sintering are clearly quite different. CO, CO2 and NOx emission was observed over the entire sintering process and varied slightly as the sintering process progressed. However, the SO2 and H2O emissions were observed only towards the completion of the sintering process. Both the CO and CO2 concentrations in the waste gas increased with the increasing substitution of charcoal for coke breeze; however the concentrations of SO2 and NOX in the waste gas decreased.
A Fundamental Study of the Cocombustion of Coke and Charcoal during Iron Ore Sintering
Energy & Fuels, 2018
In a global carbon cycle, the net greenhouse gas (e.g., CO 2) emissions can be significantly reduced if fossil fuels could be substituted with renewable and cleaner biomass-derived fuels. In the traditional iron ore sintering process, the complete replacement of coke-a coal derived fuel-with charcoal is not possible because the two fuels have very different properties and combustion behaviours, resulting in an unacceptable deterioration in sintering performance. Consequently, only low substitution ratios can be tolerated. However, research has indicated that this ratio can be increased through altering the combustion behaviour of charcoal. Most fuel particles in a sintering bed have an encapsulated layer of fine ore and flux particles. Through intentionally altering the properties of this adhering layer, combustion behaviour can be altered, leading to improved sintering performance. This work uses a newly-developed combustion model and a 2D sintering model to appropriately describe the combustion behaviour in sintering based on fuel properties and defines the optimum thickness and porosity of the adhering layer. In this study, the required properties of the adhering layer encapsulating charcoal particles-so as to match the combustion behaviour of coke particles-is determined theoretically. This study also shows that the conditions required for different fuels to have similar sintering performance are: (a) comparable ignition temperature and overall combustion rate, and (b) comparable rates of combustion at various temperatures. Matching the overall combustion rate alone does not necessarily result in comparable sintering performance. Meanwhile, the apparent density and water holding capacity of the substituting fuels should be close to the equivalent values for coke to ensure similar granulation performance and, subsequently, the properties of the bed prepared for sintering. Until these conditions are fully met, combustion efficiency, the properties of the formed flame front (e.g., width, temperature, and speed) and, consequently, sintering performance will deteriorate. In practice, fully matching all these conditions are difficult. The present work has given guidelines on which are the critical variables of the adhering fines layer that have to be considered when charcoal is introduced into sintering and also how the variable interact to determine flame front properties.
THERMODYNAMIC STUDY OF UTILIZATION OF SAWDUST FROM OAK-WOOD IN THE IRON-ORE SINTERING PROCESS
14th SGEM GeoConference on SCIENCE AND TECHNOLOGIES IN GEOLOGY, EXPLORATION AND MINING, 2014
The aim of this study was to evaluate, from thermodynamic point of view, the possibilities of sawdust from oak-wood utilization in iron-ore sintering process. Sawdust from oak-wood with standard coke breeze were studied as sintering fuels. Materials used in this study were subjected to chemical and physical analyses typically used for coal and coke characterisation. Sawdust from oak-wood has lower content of fixed carbon and higher volatile matter content. Sawdust from oak-wood has relatively low calorific values (16,90 MJ/kg) compared with coke breeze (28,16 MJ/kg). It can be observed from the chemical analyses that sawdust from oak-wood has lower sulphur level and much lower ash content, in comparison with the coke breeze. In order to visualize feasibility of individual reactions depending on temperature, Gibbs equilibrium diagrams were calculated by thermodynamic modelling program HSC Chemistry 5.11. From analysis of fuels burning reactions follows, that the highest temperatures in the sintering bed (experimental about 1150 -1360 o C) are achieved with the coke breeze. Combustion of higher amount of volatile matter in sawdust from oakwood leading to the lower maximum temperatures in the sintering bed (experimental about 780 -1180 o C). It was found that less of this energy would be available in sinter making due to the evaporation of some of the volatile matter ahead of the flame front. Overall the results suggest that it is realistic to substitute maximum 8-10% of coke breeze with sawdust from from oak-wood in the iron ore sintering process.
Biomass–Coal Hybrid Fuel: A Route to Net-Zero Iron Ore Sintering
Sustainability
The global steel industry uses fossil fuels to produce millions of tonnes of iron ore sinter each year. Sintering is an energy-intensive process that fuses iron ore and flux to produce material that balances a high mechanical strength at a sufficient particle size to ensure a macroporous burden in the blast furnace to enable rapid gas flow. As significant CO2 greenhouse emissions are emitted, the defossilisation of these CO2 emissions is vital to net-zero carbon targets. Two iterations of a new biomass–coal hybrid fuel (ecoke®(A) and ecoke®(B)) were compared with coke breeze and an anthracite coal using oxygen bomb calorimetry, simultaneous thermal analysis (STA) combining thermogravimetry and differential scanning calorimetry, and isoconversional kinetic modelling and pyrolysis–GCMS to study the volatile matter. The calorific values of both ecoke®(A) and (B) were marginally higher than that of the coke breeze: 27.9 MJ/kg and 27.8 MJ/kg, respectively, compared with 26.5 MJ/kg for th...
Energies
The problem of biomass combustion and co-combustion is a particularly important aspect of many district heating systems, where the use of biomass makes it possible to reduce CO2 emissions. The present article is a continuation of previous studies of the behavior of the mineral matter of selected fuels during the sintering processes. Three biomasses were studied: wheat straw, barley straw and rye straw, as well as two coals from Polish mines: bituminous coal and lignite. The study included ultimate and proximate analyses and oxide analysis. On the basis of the oxide analysis and using FactSage 8.0. software, the sintering process of ash from selected fuels was simulated. In particular, the content of the slag phase as well as the values of the specific heat cp and density were determined without considering the gas phase. The obtained results were compared with the results of measurements of fracture stress (mechanical method) and pressure drop (pressure drop test) determined during ...
The study of sunflower seed husks as a fuel in the iron ore sintering process
Minerals Engineering, 2008
An investigation was carried out into the use of sunflower seed husks as a supplementary fuel in the iron ore sintering process. Fuel blends were prepared by mixing different amounts of sunflower seed husks and coke in order to produce the same heat output as 5% coke breeze. Sinter pot experiments with fuels containing different amounts of sunflower seed husks and coke indicate that substituting 10% coke with sunflower seed husks did not significantly change the combustion characteristics of the sintering process or the sinter quality. The relative abundances of PCDD/Fs and PAHs obtained with the experimental sintering pot were almost identical to those of a production sinter plant, which indicates that the mechanism of formation of the organic compounds in the sintering pot were very similar. Similar values of PCDD/F I-TEQ and B[a]P-eq were obtained in the waste gas with both coke and coke with 10% coke substitution with biomass, although sintering with biomass substitution resulted in slightly higher concentrations of 2,3,7,8-tetraCDF, 1,2,3,7,8-pentaCDF and OCDD. The emission profile of targeted PAHs was also altered to a limited extent, particularly with regard to concentrations of fluorene, phenanthrene and anthracene. Overall the results suggest that it is feasible to substitute 10% coke breeze with biomass in the iron ore sintering process.
The Study of Saw-Dust Addition on Iron-Ore Sintering Performance
Acta Metallurgica Slovaca - Conference, 2014
An investigation was carried out into the use of sawdust form oak wood as a supplementary fuel in the iron ore sintering process. The primary fuel was coke breeze and total heat output of all the tested raw blends was the same and was calculated as 3.8 wt. % coke breeze. The coke substitution and energy requirement provided by sawdust from oak wood (SDOW) was in the range of 8-44 %. Experimental tests were made by using a laboratory sinter pot (LSP) with charge capacity of around 70-90 kg per run. The main objective of the work reported here was to determine the effects of substituting coke with sawdust from oak wood in the iron ore sintering process with respect to combustion efficiency and sinter quality. The use of SDOW fuel up to 20 % as a partial substitution of coke resulted in a decrease in the sintering time but on the other hand with the increasing of SDOW the bed temperatures were reduced. A substitution of coke with SDOW more than 20 % may lead to decrease in permeability of mixture and consequently it may lead to achieve low temperature profile of bed. Explain in more detail and interpretation of results is described in the paper.
Sintering of Pellets, Compound by Fly Ash, Clay and Charcoal in a Fixed Bed Combustion Reactor
Journal of Mechanics Engineering and Automation, 2016
Normally, industries in general, produce waste at its majority toxic, such as fly ash, for example, which damage the environment. The aim of this paper is to investigate the evolution of the temperature in a combustion reactor, full of pellets manufactured with fly ash, clay and charcoal powder, after sintering, to obtainment synthetic aggregates for use in civil construction. The pellets were produced in a cement mix. For realization of the work, a co-current combustion reactor was made in order to analyze the temperatures profile and investigate if the values of these temperatures would be sufficient to initiate the process of sintering of the pellets. Temperatures reached in the reactor varied in the range of 800 °C-1,290 °C. These values are sufficient to initiate the process of sintering of the pellets. For the experiment realized, parameters such as inlet velocity of the fluid (air), diameters of the pellets and size of charcoal crushed in a disk mill were varied and the effect of variations of these parameters were analyzed for the experiment. The historical temperatures were recorded by a data acquisition instrument and subsequently plotted for analysis.