Preparation of sinter with low reduction degradation index for COREX reduction in a high proportion

The sinter with low reduction degradation index(RDI)for COREX reduction was prepared by separated granulation sintering process.The results illustrate that the productivity and tumble index are attained to be 1.64 t m^(-2)h^(-1)and 59.25%,respectively,in pot tests under the optimal conditions.Under the reducing condition simulating COREX shaft furnace,RDI_(+6.3 mm),RDI_(+3.15 mm),and reducibility index of the sinter reach 63.05%,81.52%,and 83.65%,respectively.Compared with traditional sintering process,the productivity rose by 14.69%,and RDI_(+6.3) mm and RDI_(+3.15) mm were increased by 157.54%and 32.70%,respectively.In addition,as the proportion of sinter reached 60%,RDI_(+6.3 mm)and RDI_(+3.15 mm)of comprehensive burden were achieved to be 73.39%and 84.28%,respectively,which could completely meet the requirement of COREX shaft furnace for RDI.The mechanism was demonstrated that the more silicoferrites of calcium and aluminum and silicate phase occurred as well as magnetite,and the amount of Fe_(2)O_(3)decreased substantially in the sinter by separated granulation sintering process.Hence,the low-temperature reducing stress is restrained,with the increase in sinter strength.

Low Temperature Reduction Degradation Characteristics of Sinter,Pellet and Lump Ore

The reduction degradation characteristics of typical sinter, pellet and lump ore were tested with the reducing gas conditions simulating two kinds of irowmaking processes. The results show that, in the same condition of gas composition and temperature, the reduction degradation degree （RDI〈3.15mm） of sinter is high, RDI〈3.15mm of lump ore is low and RDI〈3.15 mm of pellet is in the middle level. With two kinds of gas composition simulating different iron-making processes, the reduction degradation indices （RDI） of three kinds of iron ores all present the tenden- cy of ＂inverted V-shape＂ in the temperature range from 450 to 650℃, and the RDI reach the maximum value at 550℃. The reduction degradation degrees of iron ores are extended when mixing the gas with hydrogen to increase the re duction potential, and the influence extent is discrepant for different iron ores. Colligating the increase amplitude of grains in small size fraction, the influence of reducing gas on lump ore is the greatest, the influence on sinter is the second, and the sensitivity of pellet on the reducing gas properties change is relatively small. As for the degradation form, lump ore and sinter both present the degradation ,of cracking, and the distribution of small grains generated from the cracking is in the range from 03 5 to 6. 3 mm uniformly. The lump ore presents surface cracking, while sin- ter presents integral cracking. The pellet presents the degradation of surface stripping, and the proportion of grains smaller than 0.5 mm is the highest, which is up to 90% in the grains smaller than 3.15 mm.

Comparative Studies on Degradation of Methyl Orange by Nanostructured Zinc and Zinc Oxide Films

Nanostructured zinc and zinc oxide films were prepared by magnetron sputtering processes and succeeded air annealing treatments. Comparison of reductive degradation rate of methyl orange （MO） by zinc films and photocatalytic degradation rate of MO by zinc oxide films was carried out. Both reductive degradation and photocatalytic degradation process of MO by zinc and zinc oxide films can be described by first order kinetic model. It was found that although MO liquid was most quickly decolorized by metallic zinc films, the mineraliza- tion of MO was not thorough. Observation of extra ultraviolet absorption peaks indicated the formation of aromatic intermediates. On the other hand, although the photocatalytic degradation rate of MO liquid by ZnO films was only as about 1/4 large as the reductive degradation rate by zinc films, no signs of aromatic intermediates were found. Moreover, it was found that partially oxidized zinc oxide film showed higher photocatalytic efficiency than the totally oxidized ZnO films. Synergy effect between zinc and zinc oxide phase in the partially oxidized films was considered to be responsible for the higher photocatalytic efficiency.

Reducing process of sinter in COREX shaft furnace and influence of sinter proportion on reduction properties of composite burden

In order to reduce the materials cost of COREX ironmaking process,sinter has been introduced into the composite burden in China.This work explored the reducing process of sinter in COREX shaft furnace to clarify its reduction properties change and then the effect of sinter proportion on metallurgical performance of composite burden was investigated.The results show that the reducing process of sinter in COREX shaft furnace was basically same with that in blast furnace but sinter seems like breaking faster.Under reducing condition simulated COREX shaft furnace,sinter possessed the worst reduction degradation index(RDI)and undifferentiated reduction index(RI)compared with pellet and iron ore lumps.Macroscopic and microscopic mineralogy changes indicated that sinter presents integral cracking while pellet and lump ore present surface cracking,and no simple congruent relationship exists between cracks of the burden and its ultimate reduction degradation performance.The existence of partial metallurgical performance superposition between composite and single ferrous burden was confirmed.RDI_(+6.3)≥70%and RDI_(+3.15)≥80%were speculated as essential requirements for the composite burden containing sinter in COREX shaft furnace.

Effect of pyroxenite and olivine minerals as source of MgO in hematite pellet on improvement of metallurgical properties

Pelletization of hematite ore requires high fineness and very high induration temperature（~1325 ℃） owing to its poor diffusion bonding unlike magnetite ore. Further, high-alumina hematite pellets show very high reduction degradation index（RDI） during low temperature（500-650 ℃） reduction due to their volume expansion and lattice distortion. Noamundi（India） hematite ore contains very high Al2O3（2.3%） with adverse ratio of alumina to silica（~2） for which, it shows very high RDI. In this work, the acid pellets prepared from Noamundi ore fines of optimum Blaine fineness show good cold crushing strength（CCS）. However, it shows very high RDI（77%）. In order to reduce RDI, Mg O in form of two different gangue-containing fluxes, such as pyroxenite and olivine in varying quantities has been added. The optimum requirement and performance of these fluxes has been examined and compared. Both pyroxenite and olivine fluxed pellets show significant lowering of RDI（26% and 23%, respectively） and improvement of other properties, viz CCS, swelling indices etc with good reducibility（70%-77%）. Finally, a good quality acidic hematite pellet was developed from high-alumina ore without using any lime which is very important charge material in combination of basic sinter in blast furnace.

Electro-polymerization fabrication of PANI@GF electrode and its energy-effective electrocatalytic performance in electro-Fenton process

An energy-effective polyaniline coated graphite felt （PANI@GF） composite cathode for the elec- tro-Fenton （E-Fenton） process was synthesized through an electro-polymerization method. The electrocatalytic activity of the cathode for the 2e- ORR process was investigated and dimethyl phthalate （DMP） was used as a model substrate to evaluate its performance in the E-Fenton process. The as-prepared PANI@GF composite possessed a three-dimensional porous structure, which is favorable for 02 diffusion, while the large amount of N atoms in the conductive polyaniline （PANI） enhanced 2e- ORR reactivity. The DMP degradation of the E-Fenton system using PANI@GF was significantly enhanced owing to the improvement in ORR performance. The apparent kinetic con- stant for DMP degradation was 0.0753 min-1, five times larger than that of GF. The optimal carboni- zation temperature and polymerization time for the preparation of the PANI@GF composite cath- ode was found to be 900 ℃ and 1 h, respectively. Measurement conditions are a crucial factor for proper evaluation of cathode electrocatalytic performance. Accordingly, the 02 flow rate, Fe^2＋ con- centration, and pH for DMP degradation were optimized at 0.4 L/min, 1.0 mmol/L, and 3.0, respec- tively. These results indicate that the present PANI@GF composite cathode is energy-effective and promising for potential use as an E-Fenton system cathode for the removal of organic pollutants in wastewater.

Integration of Ru/C and base for reductive catalytic fractionation of triploid poplar

Lignin,which is the most recalcitrant component of lignocellulosic biomass,is also the most abundant renewable aromatic resource.Herein,reductive treatment of triploid poplar sawdust by the integration of catalytic Ru/C and a base,which afforded high yields of phenolic monomers from the lignin component and a solid carbohydrate pulp,is reported.The introduction of Cs_(2)CO_(3) led to the generation of C2 side‐chained phenols through the cleavage of C_(β)–O and C_(β)–C_(γ) bonds inβ–O–4 units in addition to C3 side‐chained phenols;the relationship between C2 and C3 was dependent on the base dosage.The reaction conditions,including base species,temperature,time,and H_(2) pressure,were optimized in terms of phenolic product distribution,delignification degree,and carbohydrate retention.The carbohydrate pulps generated from reductive catalytic fractionation in the presence of Cs_(2)CO_(3) were more amenable to enzymatic hydrolysis,indicating that this treatment of biomass constituted the fractionation of biomass components together with the breakdown of biomass recalcitrance.

Kinetics of nitrobenzene degradation coupled to indigenous microorganism dissimilatory iron reduction stimulated by emulsified vegetable oil

Widespread contamination by nitrobenzene（NB） in sediments and groundwater requires better understanding of the biogeochemical removal process of the pollutant. NB degradation, coupled with dissimilatory iron reduction, is one of the most efficient pollutant removal methods. However, research on NB degradation coupled to indigenous microorganism dissimilatory iron reduction stimulated by electron donors is still experimental. A model for remediation in an actual polluted site does not currently exist.Therefore, in this study, the dynamics was derived from the Michaelis–Menten model（when the mass ratio of emulsified vegetable oil and NB reached the critical value 91：1）. The effect of SO4^（2-）, NO3^-, Ca^（2＋）/Mg^（2＋）, and the grain size of aquifer media on the dynamics were studied, and the NB degradation dynamic model was then modified based on the most significant factors. Utilizing the model, the remediation time could be calculated in a contaminated site.

Degradation and fate of 2,4-dinitroanisole(DNAN)and its intermediates treated with Mg/Cu bimetal:Surface examination with XAS,DFT,and LDI-MS

A novel Mg-based bimetal reagent(Mg/Cu)was used as an enhanced reductive system to degrade insensitivemunition 2,4-dinitroanisole(DNAN),a contaminant found in energeticladenwaste.Degradation ofDNANwas significantly impacted by dissolved oxygen and studied in anoxic and oxic bimetal systems(i.e.,purging with N2,air,or O_(2) gas).Degradation occurred through sequential nitroreduction:first one nitro group was reduced(ortho or para)to form short-lived intermediates 2-amino-4-nitroanisole or 4-amino-2-nitroanisole(2-ANAN or 4-ANAN),and then subsequent reduction of the other nitro group formed 2,4-diaminoanisole(DAAN).The nitro-amino intermediates demonstrated regioselective reduction in the ortho position to 2-ANAN;Regioselectivity was also impacted by the anoxic/oxic environment.Under O_(2)-purging DNAN degradation rate was slightly enhanced,but most notably O_(2) significantly accelerated DAAN generation.DAAN also further degraded only in the oxygenated Mg/Cu system.Adsorption of DNAN byproducts to the reagent occurred regardless of anoxic/oxic condition,resulting in a partition of carbon mass between the adsorbed phase(27%-35%)and dissolved phase(59%-72%).Additional surface techniqueswere applied to investigate contaminant interaction with Cu.Density functional theory(DFT)calculations identified preferential adsorption structures for DNAN on Cu with binding through two O atoms of one or both nitro groups.X-ray absorption spectroscopy(XAS)measurements determined the oxidation state of catalyticmetal Cu and formation of a Cu-O-N bond during treatment.Laser desorption ionization mass spectrometry(LDI-MS)measurements also identified intermediate 2-ANAN adsorbed to the bimetal surface.

Sintered Ore Sprayed by Acid and Alkaline Waste Water Resulted From Cold Rolling

In order to prevent the powdering of a sintered ore from influencing the smooth operation of a blast furnace,the conventional way to deal with it is that the CaCl2 solution is prepared by tap water,and then the solution is sprayed onto the sintered ore for improving its RDI（low temperature reduction degradation index）.The CaCl2 solution prepared by adding acid and alkaline waste water resulted from cold rolling is sprayed onto the sintered ore to improve its RDI.The values of RDI＋6.3 and RDI＋3.15 of the sintered ore which is sprayed by the CaCl2 solution with the CaCl2 concentration of 3.5%（mass percent） are increased by 17.5% and 11.63%,but the index of RDI-0.5 is decreased by 3.1% when the spraying amount of the solution is making up 0.5% of the total sintered ore sprayed in comparison with those of the sintered ore which is not sprayed by using the CaCl2 solution.Experimental results show that after the CaCl2 solutions prepared by adding the acid and alkaline waste water are sprayed on the sintered ore,RDI of the ore can be remarkably improved and therefore another way for recycling acid and alkaline waste water can be available,by which both cost for treating waste water and cost for producing a sintered ore can be decreased and environment is free of pollution by harmful substances in the waste water.