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As a renewable resource of reducer, biochar prepared by pine sawdust is proposed for direct reduction of copper slag in this paper. Combined with thermodynamic analysis, effects of reduction time, temperature and CaO addition ratio on solid copper slag reduction characteristics are discussed. The oxides of iron in copper slag are Fe3O4 and 2FeO·SiO2. The reduction processes were carried out step by step for Fe3O4 and 2FeO·SiO2, respectively: Fe3O4 → FeO → Fe and 2FeO·SiO2 → Fe. The porous structure of biochar exhibits higher reduction reactivity and reaction rate than that of coal. CaO reduced the Gibbs free energy of reduction reactions and facilitated the reduction of 2FeO·SiO2 with C and CO. When CaO was added, separation reaction of FeO and SiO2 took place and α-SiO2 and β-SiO2 were produced. When the addition ratio of CaO is above 0.3, CaO·SiO2 and 2CaO·SiO2 are produced. The reduction process of copper slag was established as follows: (a) dehydration and fast pyrolysis; (b) reduction of iron oxides by C and CO; and (c) sweating metallic iron outflows from cracks in pellet. Besides, direct reduction reaction mechanism and transport process of Cu are established based on reduction experiments, XRD and SEM-EDS analysis. [ABSTRACT FROM AUTHOR]

Through thermodynamic analysis, the CO2 sorbent(s) used in the steam reforming process of ethanol as the model compounds of bio-oil was selected from nine common metal oxides. Among them, calcium oxide shows the best CO2 adsorption capacity in the condition of the co-existence of CO2 and H2O in the temperature zone (600-1100 K) where ethanol steam reforming can obtain a higher hydrogen yield, and its carbonate (CaCO3) can easily decompose at slightly higher temperature. Compared to the ethanol steam reforming process with the addition of no any sorbent, the hydrogen yield and purity in the process with CaO as a sorbent were obviously improved, and the temperature range of more than 90% hydrogen yield is widened from 860-1010 K to 705-1085 K. Before the sorbent addition, the maximum hydrogen concentration appear at over 750 K, yet just around 74%, but the hydrogen concentration can overtake 90% in the range of 590-935 K after the addition of CaO. With thermogravimetric analysis, CaO from calcinated calcium acetate shows the highest CO2 adsorption capacity and the best cycle stability, as compared to the other two kinds of CaO, with analytical pure and from calcinated calcium hydroxide. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 1208-1214, 2015 [ABSTRACT FROM AUTHOR]

With the minimization of the Gibb's free energy, the thermodynamical analysis of the steam reforming processes for the four typical model compounds (ethanol, acetic acid, acetone, and phenol) of bio-oil was systematically performed. In the steam reforming process, the four model compounds can be completely converted. The higher hydrogen yields of the four compounds were obtained via steam reforming than via thermal decomposition. The hydrogen yields first increased and then remained constant and even decreased with temperature, monotonically decreased with the pressure increase, and obviously increased with the steam to carbon ratio. As the steam to carbon ratio rose, the temperatures of the maximum hydrogen yields move afterward to low temperature. When the S/C ratio was 6, the increase rate of hydrogen was decreased. In the co-existence of CaO/CO2/H2O, the reaction between CaO and CO2 was dominant to the reaction between CaO and H2O. By adding CaO, a CO2 sorbent in the steam reforming system, both the yields and the concentration of hydrogen were obviously more pronounced than the processes without CaO. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 1008-1016, 2014 [ABSTRACT FROM AUTHOR]

The sinter process of iron ore with biomass carbon instead of coke breeze as fuel was investigated via thermodynamic analysis in this paper through a comparison of sinter composition indexes, metallurgical properties, and pollutant emissions. Straw charcoal was used in this paper, and its replacement does not adversely affect the composition index of iron ore, namely Fe, FeO, basicity, S, nor the metallurgical properties, namely reduction degradation index and reduction index. However, the replacement has a great effect on the emissions of pollutant gases, including SO2, NOx, CO, and CO2. The thermodynamic analysis result shows that emissions of pollutant gases produced in the sinter process significantly decrease by using straw charcoal instead of coke breeze in sinter. The sintering maximum temperature has a great influence on sintering technical indicators. The best sintering maximum temperature is between 1300 and 1400 °C, where sinter ore with high quality can be obtained. [ABSTRACT FROM AUTHOR]

Combined steam/dry reforming of bio-oil with blast furnace slag as heat carrier for the syngas production with the H 2 /CO ratio of 3:1 for further methanation, was investigated. The increase of H 2 O addition can increase the total yield of H 2 and CO, but also increase the critical temperature at which 3:1-H 2 /CO syngas was obtained, while the increase of CO 2 addition can decrease the critical temperature, but the syngas yield was also decreased. When the steam/carbon (S/C) ratio was 3.0 and the CO 2 /carbon (CO 2 /C) ratio was 0.5, the critical temperature decreased to 804 °C, with the potential H 2 yield of over 90%. Although the addition of slag and how much slag to be added had almost no any thermodynamic effect on the combined reforming of bio-oil under the condition where higher potential H 2 yield can be obtained, the slag as heat carrier could supply all heat for the combined reforming process. When the added slag mass was 3.99 times bio-oil mass, the combined reforming at the S/C ratio of 3.0 and the CO 2 /C ratio of 0.5 can occur spontaneously for the production of 3:1-H 2 /CO syngas. The present study could offer important guidance toward utilization of this novel process for further methanation. • Combined steam/dry reforming for syngas production and further methanation. • BF slag as heat carrier supplies all the heat for the bio-oil reforming process. • Low consumptions of feedstock and energy were pursued. [ABSTRACT FROM AUTHOR]

In this paper, a thermodynamic analysis of the synergistic coal/CO 2 /H 2 O gasification process with BFS (blast furnace slag) as heat carrier was performed using the Gibbs free energy minimization approach through Lagrange multiplier method. The effect of temperature, pressure and C/CO 2 /H 2 O were investigated. Carbon, CO 2 and H 2 O conversion, H 2 and CO yield, and H 2 /CO ratio were used to characterize the synergistic gasification performance. The results showed that the atmospheric pressure was preferable for coal gasification and the increasing of temperature caused the increase in carbon conversion and syngas production. The optimal temperature of the synergistic gasification was 800–900 °C. Not only did it ensure the coal gasification reaction completely, but also it recovered the BFS waste heat effectively. The results clearly showed that the addition of H 2 O and CO 2 could lead to the reduction of the carbon residue and increase of the production of H 2 and CO, respectively. Meanwhile, it was beneficial to reduce the waste heat using to heating extra steam and enhance the coal/CO 2 gasification reaction rate by controlling the addition of CO 2 and H 2 O reasonably. Moreover, the production syngas application was also investigated by changing the relative CO 2 /C ratio and H 2 O/C ratio in the feed to modify the H 2 /CO ratio. [ABSTRACT FROM AUTHOR]