The using of the iron to extract reduced iron with T Fe ≥ 69.5% Al 2O 3+SiO 2<0.3% was studied. Preparation of reduced iron powder in this experimental research can produce ultra pure magnetite concentrate...The using of the iron to extract reduced iron with T Fe ≥ 69.5% Al 2O 3+SiO 2<0.3% was studied. Preparation of reduced iron powder in this experimental research can produce ultra pure magnetite concentrate. The quality of the final product reaches the product standard of SC 100.26 and NC 100.24.展开更多
The potential of microbial mediated iron plaque reduction, and associated arsenic (As) mobility were examined by iron reducing bacteria enriched from As contaminated paddy soil. To our knowledge, this is the first t...The potential of microbial mediated iron plaque reduction, and associated arsenic (As) mobility were examined by iron reducing bacteria enriched from As contaminated paddy soil. To our knowledge, this is the first time to report the impact of microbial iron plaque reduction on As mobility. Iron reduction occurred during the inoculation of iron reducing enrichment culture in the treatments with iron plaque and ferrihydrite as the electron acceptors, respectively. The Fe(II) concentration with the treatment of anthraquinone-2, 6-disulfonic acid (AQDS) and iron reducing bacteria increased much faster than the control. Arsenic released from iron plaque with the iron reduction, and a significant correlation between Fe(II) and total As in culture was observed. However, compared with control, the increasing rate of As was inhibited by iron reducing bacteria especially in the presence of AQDS. In addition, the concentrations of As(III) and As(V) in abiotic treatments were higher than those in the biotic treatments at day 30. These results indicated that both microbial and chemical reductions of iron plaque caused As release from iron plaque to aqueous phase, however, microbial iron reduction induced the formation of more crystalline iron minerals, leading to As sequestration. In addition, the presence of AQDS in solution can accelerate the iron reduction, the As release from iron plaque and subsequently the As retention in the crystalline iron mineral. Thus, our results suggested that it is possible to remediate As contaminated soils by utilizing iron reducing bacteria and AQDS.展开更多
Forty-six candidate phenol/benzoate degrading-iron reducing bacteria were isolated from long term irrigated tropical paddy soils by enrichment procedures.Pure cultures and some prepared mixed cultures were examined fo...Forty-six candidate phenol/benzoate degrading-iron reducing bacteria were isolated from long term irrigated tropical paddy soils by enrichment procedures.Pure cultures and some prepared mixed cultures were examined for ferric oxide reduction and phenol/benzoate degradation.All the isolates were iron reducers,but only 56.5%could couple iron reduction to phenol and/or benzoate degradation,as evidenced by depletion of phenol and benzoate after one week incubation.Analysis of degradative capability using Biolog...展开更多
Batch and column experiments were conducted to determine whether zerovalent iron (ZVI) and sulfate reducing bacteria (SRB) can function synergistically and accelerate pollutant removal. Batch experiments suggest that ...Batch and column experiments were conducted to determine whether zerovalent iron (ZVI) and sulfate reducing bacteria (SRB) can function synergistically and accelerate pollutant removal. Batch experiments suggest that combining ZVI with SRB can enhance the removal of U(Ⅵ) synergistically. The removal rate of U(Ⅵ) in the ZVI+SRB combining system is obviously higher than the total rate of ZVI system and SRB system with a difference of 13.4% at t=2 h and 29.9% at t=4 h. Column experiments indicate that the reactor filled with both ZVI and SRB biofilms is of better performance than the SRB bioreactor in wastewater basification, desulfurization and U(Ⅵ) fixation. The results imply that the ZVI+SRB permeable reactive barrier may be a promising method for treating subsurface uranium contamination.展开更多
The study is aimed at the problem of high content of Cr^(6+),Cr^(3+)and SO_(4)^(2-)is high and low pH value in acid mine drainage(AMD).Moreover,treatment of AMD by sulfate reducing bacteria(SRB)requires the addition o...The study is aimed at the problem of high content of Cr^(6+),Cr^(3+)and SO_(4)^(2-)is high and low pH value in acid mine drainage(AMD).Moreover,treatment of AMD by sulfate reducing bacteria(SRB)requires the addition of carbon source,while the treating effectiveness is not good enough on its own.The sugarcane slag,the corn cob and the sunflower straw were selected as the SRB carbon source cooperating with iron scrap to construct the dynamic columns 1,2 and 3.The mechanism of removing Cr^(6+),Cr^(3+),SO_(4)^(2-)and H+and the regularity of sustained release of carbon source and TFe release was studied in AMD.The removal efficiency of heavy metal ions,the ability of sustained release of carbon source,and the ability of adjusting acid by the three dynamic columns were compared.The result shows that the average removal rates of Cr^(6+),Cr^(3+)and SO_(4)^(2-)in effluent of dynamic column 1,filled by sugarcane slag,iron scrap and SRB,were 96.9%,67.1%and 54.3%.The average release of TFe and chemical oxygen demand(COD)were 4.4 and 287.3 mg/L.Its average pH was 6.98.Compared with the performance of dynamic columns 1,2 and 3,dynamic column 1 performed best in removing Cr^(6+),Cr^(3+)and SO_(4)^(2-)from AMD and controlling the release of COD and TFe,adjusting the pH of the solution.The study is of significance in treatment of AMD by taking for biomass materials as SRB carbon source in cooperation with iron scrap.展开更多
The features of the techniques of fast reducing roasting (FRR) and conventional magnetic roasting, as well as tremendous demands of iron ores in iron and steel industry of China, were briefly described. The test equip...The features of the techniques of fast reducing roasting (FRR) and conventional magnetic roasting, as well as tremendous demands of iron ores in iron and steel industry of China, were briefly described. The test equipment suitable for FRR of fine-grained materials was introduced. Weakly magnetic materials with grain size of <0.30 mm were converted into strongly magnetic materials by FRR for several to dozens of seconds. In a weakly reducing atmosphere and at 740-800 °C, refractory powder iron material (<0.30 mm) which is rich in specularite, limonite and Mg-Mn siderite was subjected to FRR for a few seconds to 60 s. Concentrate with iron grade of 55.67%-55.21%, high contents of Mg and Mn in the ore is obtained and the yield of magnetic separation reaches 81.66%-86.57%. The results of X-ray diffraction (XRD) analysis and magnetism detection of the material before and after FRR indicate that weakly magnetic material is mainly converted into strongly magnetic material Fe3O4 with specific saturation magnetic moment. The efficiency of FRR is consistent with TFe recovery of magnetic separation; meantime, the specific saturation magnetic moment increases from 33 to 42 times after FRR. Calculations show that speeds of flash magnetic roasting are obtained from several dozen to two or three hundred times, compared with rotary kiln or shaft furnace. This indicates that it is practicable to use the fast reducing roasting technique to improve the comprehensive utilization of iron ore resources.展开更多
Iron toxicity is one of the main edaphic constraints that hamper rice production in West African savanna and forest lowlands. Although chemical reduction processes of various types of pedogenic iron oxides could not b...Iron toxicity is one of the main edaphic constraints that hamper rice production in West African savanna and forest lowlands. Although chemical reduction processes of various types of pedogenic iron oxides could not be underestimated, the bulk of these processes can be ascribed to the specific activity of Iron-Reducing Bacteria (IRB). The reducing conditions of waterlogged lowland soils boost iron toxicity through the reduction of almost all iron into ferrous form (Fe2+), which can cause disorder in rice plant and crop yield losses. Aiming to contribute at the improvement of rice yield in Africa, an experiment was developed to evaluate the impact of subsurface drainage on IRB dynamics and activity during rice cultivation. Twelve concrete microplots with a clay-loam soil and a rice variety susceptible to iron toxicity (FKR 19) were used for the experiment. Soil in microplots was drained for 7 days (P1), 14 days (P2), and 21 days (P3), respectively. Control (T) microplots without drainage were prepared similarly. The evolution of IRB populations and the content of ferrous iron in the paddy soil and in soil near rice root were monitored throughout the cultural cycle using MPN and colorimetric methods, respectively. Data obtained were analyzed in relation to drainage frequency, rice growth stage, and rice yield using the Student t test and XLSTAT 7.5.2 statistical software. From the results obtained, the subsurface drainage reduced significantly IRB populations (p = 0.024). However, the drainage did not affect significantly ferrous iron concentration in the soil near rice roots (p = 0.708). The concentration of ferrous iron (p < 0.0001) in soil near rice roots and the number of IRB (p < 0.0001) were significantly higher during the rice tillering and maturity stages. Although no significant difference was observed for rice yield among treatments (p = 0.209), the P2 subsurface drainage showed the highest yield and the lowest concentration of ferrous iron in soil near rice roots.展开更多
The increasing consumption of plastics inevitably results in increasing amounts of waste plastics. Because of their long degradation periods, these wastes negatively affect the natural environment. Numerous studies ha...The increasing consumption of plastics inevitably results in increasing amounts of waste plastics. Because of their long degradation periods, these wastes negatively affect the natural environment. Numerous studies have been conducted to recycle and eliminate waste plastics. The potential for recycling waste plastics in the iron and steel industry has been underestimated; the high C and H contents of plastics may make them suitable as alternative reductants in the reduction process of iron ore. This study aims to substitute plastic wastes for coal in reduction melting process and to investigate their performance during reduction at high temperature. We used a common type of waste plastic, polyethylene terephthalate (PET), because of its high carbon and hydrogen contents. Composite pellets containing PET wastes, coke, and magnetite iron ore were reduced at selected temperatures of 1400 and 1450℃ for reduction time from 2 to 10 min to investigate the reduction melting behavior of these pellets. The results showed that an increased temperature and reduction time increased the reduction ratio of the pellets. The optimum experimental conditions for obtaining metallic iron (iron nuggets) were reduction at 1450℃ for 10 min using composite pellets containing 60% PET and 40% coke.展开更多
The reducibility of iron-bearing burdens was emphasized for improving the operation efficiency of blast furnace. The blast furnace operation of charging the burdens with high reducibility has been numerically evaluate...The reducibility of iron-bearing burdens was emphasized for improving the operation efficiency of blast furnace. The blast furnace operation of charging the burdens with high reducibility has been numerically evaluated using a multi-fluid blast furnace model. The effects of reaction rate constants and diffusion coefficients were investigated separately or simultaneously for clarifying the variations of furnace state. According to the model simulation results, in the upper zone, the indirect reduction of the burdens proceeds at a faster rate and the shaft efficiency is enhanced with the improvement under the conditions of interface reaction and intra-particle diffusion. In the lower zone, direct reduction in molten slag is restrained. As a consequence, CO utilization of top gas is enhanced and the ratio of direct reduction is decreased. It is possible to achieve higher energy efficiency of the blast furnace, and this is represented by the improvement in productivity and the decrease in consumption of reducing agent. The use of high-reducibility burdens contributes to a better performance of blast furnace. More efforts are necessary to develop and apply highreducibility sinter and carbon composite agglomerates for practical application at a blast furnace.展开更多
The energy consumption of iron ore sintering process is about 10%- 15%of the total of iron and steel industry.Therefore,it is of great significance to take effective measures to reduce the energy consumption in the ir...The energy consumption of iron ore sintering process is about 10%- 15%of the total of iron and steel industry.Therefore,it is of great significance to take effective measures to reduce the energy consumption in the iron ore sintering process to reduce the costs of sintering product and cut down the emissions of harmful gases,such as CO_2 and SO_2.In this study,the technology development of saving energy and reducing emission in iron ore sintering process was reviewed and discussed;some new directions and measures of saving energy were presented for the sintering process in the future.展开更多
Rice is one of the staple crops in Burkina Faso. However, the local production covers only 47% of the population demands. One of the main reasons of the poor productivity in Burkina Faso is iron toxicity which is rela...Rice is one of the staple crops in Burkina Faso. However, the local production covers only 47% of the population demands. One of the main reasons of the poor productivity in Burkina Faso is iron toxicity which is related mainly to the activity of Iron Reducing Bacteria in the rice field’s ecosystems. In order to control the harmful effects of Iron Reducing Bacterial populations and to improve rice productivity, a pots experiment was conducted at the experimental site of the University Ouaga I Pr. Joseph KI-ZERBO. An iron toxic soil from Kou Valley (West of Burkina Faso) and two rice varieties, BOUAKE-189 and ROK-5, sensitive and tolerant to iron toxicity, respectively, were used for the experiment. The pots were drained for 14 days (D2) and amended with chemical fertilizers (NPK + Urea and NPK + Urea + Ca + Mg + Zn complexes). Control pots without drainage and fertilization (D0/NF) were prepared similarly. The kinetics of Iron Reducing Bacterial populations and ferrous iron content in soil near rice roots were monitored throughout the cultural cycle using MPN and colorimetric methods, respectively. The total iron content was evaluated in rice plant using a spectrometric method. Data obtained were analyzed in relation to drainage and fertilization mode, rice growth stage and rice yield using the Student’s t-test and XLSTAT 2014 statistical software. The experiment showed that the combined application of subsurface drainage and NPK + Urea + Ca + Mg + Zn fertilization, reduced significantly the number of IRB in the soil near rice roots for both rice varieties (p = 0.050 and p = 0.020) increased the leaf tissue tolerance to excess amounts of Fe, and rice yield.展开更多
Corrosion and electrochemical behavior of 316L stainless steel was investigated in the presence of aerobic iron-oxidizing bacteria IOB and anaerobic sulfate-reducing bacteria SRB isolated from cooling water systems in...Corrosion and electrochemical behavior of 316L stainless steel was investigated in the presence of aerobic iron-oxidizing bacteria IOB and anaerobic sulfate-reducing bacteria SRB isolated from cooling water systems in an oil refinery using electrochemical measurement, scanning electron microscopy SEM and energy dispersive atom X-ray analysisEDAX. The results show the corrosion potential and pitting potential of 316L stainless steel decrease distinctly in the presence of bacteria, in comparison with those observed in sterile medium under the same exposure time. SEM morphologies have shown that 316L stainless steel reveals no signs of pitting attack in the sterile medium. However, micrometer-scale corrosion pits were observed on 316L stainless steel sur- face in the presence of bacteria. The presence of SRB leads to higher corrosion rates than IOB. The interactions between the stainless steel surface, abiotic corrosion products, and bacterial cells and their metabolic products in- creased the corrosion damage degree of the passive film and accelerated pitting propagation.展开更多
Iron toxicity is a major stress to rice caused by a high concentration of reduced iron, in the soil in many lowlands worldwide. To reduce iron toxicity in the West African lowlands, an investigation was performed at t...Iron toxicity is a major stress to rice caused by a high concentration of reduced iron, in the soil in many lowlands worldwide. To reduce iron toxicity in the West African lowlands, an investigation was performed at the site of the University of Ouagadougou, in pots containing an iron toxic soil from the Kou Valley (West of Burkina Faso). The experiment objective was to study the effect of mineral fertilizer on Iron Reducing Bacteria (IRB) dynamics and activity during rice cultivation, iron accumulation in rice plant and rice biomass yield under iron toxicity conditions. BOUAKE-189 and ROK-5 rice varieties, sensitive and tolerant to iron toxicity, respectively, were used for the experiment. The pots were amended with chemical fertilizers (NPK + Urea and NPK + Urea + Ca + Mg + Zn complex). Control pots without fertilization were prepared similarly. The kinetics of IRB and ferrous iron content in soil near rice roots were monitored throughout the cultural cycle using MPN and colorimetric methods, respectively. The total iron content was evaluated in rice plant using spectrometric method. Data obtained were analyzed in relation to fertilization mode, rice growth stage and rice yield using the student’s t-test and XLSTAT 2014 statistical software. The experiment revealed that NPK + Urea and NPK + Urea + Ca + Mg + Zn fertilization, decreased significantly (p < 0.0001) the number of IRB in the soil for BOUAKE-189 rice varieties. In most pots, highest IRB densities and ferrous iron content in soil were recorded from rice tillering and flowering to maturity stages, indicating that rice plants promoted microbial processes and iron reduction in soil. From the study, the NPK + Urea amendment decreased significantly ferrous iron content (p < 0.0001) in soil near BOUAKE-189 and ROK-5 rice varieties roots relatively to control pots. However, NPK + Urea + Ca + Zn + Mg amendment increased significantly ferrous iron content (p < 0.0001) in the soil near roots, Fe accumulation in plant biomass and rice yield for the two rice varieties.展开更多
Field and greenhouse experiments were conducted to investigate the effects of cropping season, nitrogen fertilizer input and aerated fallow on the dynamics of phenol degradihg-iron reducing bacteria (PD-IRB) in tropic...Field and greenhouse experiments were conducted to investigate the effects of cropping season, nitrogen fertilizer input and aerated fallow on the dynamics of phenol degradihg-iron reducing bacteria (PD-IRB) in tropical irrigated rice (Oryza sativa L.) systems. The PD-IRB population density was monitored at different stages of rice growth in two cropping seasons (dry and early wet) in a continuous annual triple rice cropping system under irrigated condition. In this system, the high nitrogen input (195 and 135 kg N ha-1 in dry and wet seasons, respectively) plots and control plots receiving no N fertilizer were compared to investigate the effect of nitrogen rate on population size. The phenol degrading-iron reducing bacteria (PD-IRB) were abundant in soils under cropping systems of tropical irrigated rice. However, density of the bacterial populations varied with rice growth stages. Cropping seasons, rhizosphere, and aerated fallow could affect the dynamics of PD-IRB. In the field trial, viable counts of PD-IRB in the topsoil layer (15 cm) ranged between 102 and 108 cells per gram of dry soil, A steep increase in viable counts during the second half of the cropping season suggested that the population density of PD-IRB increased at advanced crop-growth stages. Population growth of PD-IRB was accelerated during the dry season compared to the wet season. In the greenhouse experiment, the adjacent aerated fallow revealed 1-2 orders of magnitude higher in most probable number (MPN) of PD-IRB than the wet fallow treated plots. As a prominent group Of Fe reducing bacteria, PD-IRB predominated in the rhizosphere of rice, since maximum MPN of PD-IRB (2.62×108 g-1 soil) was found in rhizosphere soil. Mineral N fertilizer rates showed no significant effect on PD-IRB population density.展开更多
文摘The using of the iron to extract reduced iron with T Fe ≥ 69.5% Al 2O 3+SiO 2<0.3% was studied. Preparation of reduced iron powder in this experimental research can produce ultra pure magnetite concentrate. The quality of the final product reaches the product standard of SC 100.26 and NC 100.24.
基金supported by the Knowledge Innovation Program of Chinese Academy of Sciences(No. KZCX1-YW-06-03)
文摘The potential of microbial mediated iron plaque reduction, and associated arsenic (As) mobility were examined by iron reducing bacteria enriched from As contaminated paddy soil. To our knowledge, this is the first time to report the impact of microbial iron plaque reduction on As mobility. Iron reduction occurred during the inoculation of iron reducing enrichment culture in the treatments with iron plaque and ferrihydrite as the electron acceptors, respectively. The Fe(II) concentration with the treatment of anthraquinone-2, 6-disulfonic acid (AQDS) and iron reducing bacteria increased much faster than the control. Arsenic released from iron plaque with the iron reduction, and a significant correlation between Fe(II) and total As in culture was observed. However, compared with control, the increasing rate of As was inhibited by iron reducing bacteria especially in the presence of AQDS. In addition, the concentrations of As(III) and As(V) in abiotic treatments were higher than those in the biotic treatments at day 30. These results indicated that both microbial and chemical reductions of iron plaque caused As release from iron plaque to aqueous phase, however, microbial iron reduction induced the formation of more crystalline iron minerals, leading to As sequestration. In addition, the presence of AQDS in solution can accelerate the iron reduction, the As release from iron plaque and subsequently the As retention in the crystalline iron mineral. Thus, our results suggested that it is possible to remediate As contaminated soils by utilizing iron reducing bacteria and AQDS.
文摘Forty-six candidate phenol/benzoate degrading-iron reducing bacteria were isolated from long term irrigated tropical paddy soils by enrichment procedures.Pure cultures and some prepared mixed cultures were examined for ferric oxide reduction and phenol/benzoate degradation.All the isolates were iron reducers,but only 56.5%could couple iron reduction to phenol and/or benzoate degradation,as evidenced by depletion of phenol and benzoate after one week incubation.Analysis of degradative capability using Biolog...
基金Project(kzcx2-yw-135-2) supported by Knowledge Innovational Program of Chinese Academy of SciencesProject(08B07) supported by Science Foundation of Hengyang Normal University
文摘Batch and column experiments were conducted to determine whether zerovalent iron (ZVI) and sulfate reducing bacteria (SRB) can function synergistically and accelerate pollutant removal. Batch experiments suggest that combining ZVI with SRB can enhance the removal of U(Ⅵ) synergistically. The removal rate of U(Ⅵ) in the ZVI+SRB combining system is obviously higher than the total rate of ZVI system and SRB system with a difference of 13.4% at t=2 h and 29.9% at t=4 h. Column experiments indicate that the reactor filled with both ZVI and SRB biofilms is of better performance than the SRB bioreactor in wastewater basification, desulfurization and U(Ⅵ) fixation. The results imply that the ZVI+SRB permeable reactive barrier may be a promising method for treating subsurface uranium contamination.
基金This work was supported by the National Natural Science Foundation of China(41672247,41102157)Liaoning Province’s“Program for Promoting Liaoning Talents”(XLYC1807159)+1 种基金2019 Nature Fund Project Guidance Plan of Liaoning Province(2019-zd-0044)2017 Youth Project of Education Department of Liaoning Province(LJ2017QL035).
文摘The study is aimed at the problem of high content of Cr^(6+),Cr^(3+)and SO_(4)^(2-)is high and low pH value in acid mine drainage(AMD).Moreover,treatment of AMD by sulfate reducing bacteria(SRB)requires the addition of carbon source,while the treating effectiveness is not good enough on its own.The sugarcane slag,the corn cob and the sunflower straw were selected as the SRB carbon source cooperating with iron scrap to construct the dynamic columns 1,2 and 3.The mechanism of removing Cr^(6+),Cr^(3+),SO_(4)^(2-)and H+and the regularity of sustained release of carbon source and TFe release was studied in AMD.The removal efficiency of heavy metal ions,the ability of sustained release of carbon source,and the ability of adjusting acid by the three dynamic columns were compared.The result shows that the average removal rates of Cr^(6+),Cr^(3+)and SO_(4)^(2-)in effluent of dynamic column 1,filled by sugarcane slag,iron scrap and SRB,were 96.9%,67.1%and 54.3%.The average release of TFe and chemical oxygen demand(COD)were 4.4 and 287.3 mg/L.Its average pH was 6.98.Compared with the performance of dynamic columns 1,2 and 3,dynamic column 1 performed best in removing Cr^(6+),Cr^(3+)and SO_(4)^(2-)from AMD and controlling the release of COD and TFe,adjusting the pH of the solution.The study is of significance in treatment of AMD by taking for biomass materials as SRB carbon source in cooperation with iron scrap.
基金Project(20070497048) supported by China Scholarship Council,Ministry of Education of China
文摘The features of the techniques of fast reducing roasting (FRR) and conventional magnetic roasting, as well as tremendous demands of iron ores in iron and steel industry of China, were briefly described. The test equipment suitable for FRR of fine-grained materials was introduced. Weakly magnetic materials with grain size of <0.30 mm were converted into strongly magnetic materials by FRR for several to dozens of seconds. In a weakly reducing atmosphere and at 740-800 °C, refractory powder iron material (<0.30 mm) which is rich in specularite, limonite and Mg-Mn siderite was subjected to FRR for a few seconds to 60 s. Concentrate with iron grade of 55.67%-55.21%, high contents of Mg and Mn in the ore is obtained and the yield of magnetic separation reaches 81.66%-86.57%. The results of X-ray diffraction (XRD) analysis and magnetism detection of the material before and after FRR indicate that weakly magnetic material is mainly converted into strongly magnetic material Fe3O4 with specific saturation magnetic moment. The efficiency of FRR is consistent with TFe recovery of magnetic separation; meantime, the specific saturation magnetic moment increases from 33 to 42 times after FRR. Calculations show that speeds of flash magnetic roasting are obtained from several dozen to two or three hundred times, compared with rotary kiln or shaft furnace. This indicates that it is practicable to use the fast reducing roasting technique to improve the comprehensive utilization of iron ore resources.
文摘Iron toxicity is one of the main edaphic constraints that hamper rice production in West African savanna and forest lowlands. Although chemical reduction processes of various types of pedogenic iron oxides could not be underestimated, the bulk of these processes can be ascribed to the specific activity of Iron-Reducing Bacteria (IRB). The reducing conditions of waterlogged lowland soils boost iron toxicity through the reduction of almost all iron into ferrous form (Fe2+), which can cause disorder in rice plant and crop yield losses. Aiming to contribute at the improvement of rice yield in Africa, an experiment was developed to evaluate the impact of subsurface drainage on IRB dynamics and activity during rice cultivation. Twelve concrete microplots with a clay-loam soil and a rice variety susceptible to iron toxicity (FKR 19) were used for the experiment. Soil in microplots was drained for 7 days (P1), 14 days (P2), and 21 days (P3), respectively. Control (T) microplots without drainage were prepared similarly. The evolution of IRB populations and the content of ferrous iron in the paddy soil and in soil near rice root were monitored throughout the cultural cycle using MPN and colorimetric methods, respectively. Data obtained were analyzed in relation to drainage frequency, rice growth stage, and rice yield using the Student t test and XLSTAT 7.5.2 statistical software. From the results obtained, the subsurface drainage reduced significantly IRB populations (p = 0.024). However, the drainage did not affect significantly ferrous iron concentration in the soil near rice roots (p = 0.708). The concentration of ferrous iron (p < 0.0001) in soil near rice roots and the number of IRB (p < 0.0001) were significantly higher during the rice tillering and maturity stages. Although no significant difference was observed for rice yield among treatments (p = 0.209), the P2 subsurface drainage showed the highest yield and the lowest concentration of ferrous iron in soil near rice roots.
基金financially supported by Yildiz Technical University Scientific Research Projects Coordination Department (No. 2011-07-02-KAP02)
文摘The increasing consumption of plastics inevitably results in increasing amounts of waste plastics. Because of their long degradation periods, these wastes negatively affect the natural environment. Numerous studies have been conducted to recycle and eliminate waste plastics. The potential for recycling waste plastics in the iron and steel industry has been underestimated; the high C and H contents of plastics may make them suitable as alternative reductants in the reduction process of iron ore. This study aims to substitute plastic wastes for coal in reduction melting process and to investigate their performance during reduction at high temperature. We used a common type of waste plastic, polyethylene terephthalate (PET), because of its high carbon and hydrogen contents. Composite pellets containing PET wastes, coke, and magnetite iron ore were reduced at selected temperatures of 1400 and 1450℃ for reduction time from 2 to 10 min to investigate the reduction melting behavior of these pellets. The results showed that an increased temperature and reduction time increased the reduction ratio of the pellets. The optimum experimental conditions for obtaining metallic iron (iron nuggets) were reduction at 1450℃ for 10 min using composite pellets containing 60% PET and 40% coke.
文摘The reducibility of iron-bearing burdens was emphasized for improving the operation efficiency of blast furnace. The blast furnace operation of charging the burdens with high reducibility has been numerically evaluated using a multi-fluid blast furnace model. The effects of reaction rate constants and diffusion coefficients were investigated separately or simultaneously for clarifying the variations of furnace state. According to the model simulation results, in the upper zone, the indirect reduction of the burdens proceeds at a faster rate and the shaft efficiency is enhanced with the improvement under the conditions of interface reaction and intra-particle diffusion. In the lower zone, direct reduction in molten slag is restrained. As a consequence, CO utilization of top gas is enhanced and the ratio of direct reduction is decreased. It is possible to achieve higher energy efficiency of the blast furnace, and this is represented by the improvement in productivity and the decrease in consumption of reducing agent. The use of high-reducibility burdens contributes to a better performance of blast furnace. More efforts are necessary to develop and apply highreducibility sinter and carbon composite agglomerates for practical application at a blast furnace.
文摘The energy consumption of iron ore sintering process is about 10%- 15%of the total of iron and steel industry.Therefore,it is of great significance to take effective measures to reduce the energy consumption in the iron ore sintering process to reduce the costs of sintering product and cut down the emissions of harmful gases,such as CO_2 and SO_2.In this study,the technology development of saving energy and reducing emission in iron ore sintering process was reviewed and discussed;some new directions and measures of saving energy were presented for the sintering process in the future.
文摘Rice is one of the staple crops in Burkina Faso. However, the local production covers only 47% of the population demands. One of the main reasons of the poor productivity in Burkina Faso is iron toxicity which is related mainly to the activity of Iron Reducing Bacteria in the rice field’s ecosystems. In order to control the harmful effects of Iron Reducing Bacterial populations and to improve rice productivity, a pots experiment was conducted at the experimental site of the University Ouaga I Pr. Joseph KI-ZERBO. An iron toxic soil from Kou Valley (West of Burkina Faso) and two rice varieties, BOUAKE-189 and ROK-5, sensitive and tolerant to iron toxicity, respectively, were used for the experiment. The pots were drained for 14 days (D2) and amended with chemical fertilizers (NPK + Urea and NPK + Urea + Ca + Mg + Zn complexes). Control pots without drainage and fertilization (D0/NF) were prepared similarly. The kinetics of Iron Reducing Bacterial populations and ferrous iron content in soil near rice roots were monitored throughout the cultural cycle using MPN and colorimetric methods, respectively. The total iron content was evaluated in rice plant using a spectrometric method. Data obtained were analyzed in relation to drainage and fertilization mode, rice growth stage and rice yield using the Student’s t-test and XLSTAT 2014 statistical software. The experiment showed that the combined application of subsurface drainage and NPK + Urea + Ca + Mg + Zn fertilization, reduced significantly the number of IRB in the soil near rice roots for both rice varieties (p = 0.050 and p = 0.020) increased the leaf tissue tolerance to excess amounts of Fe, and rice yield.
基金the National Natural Science Foundation of China (No.20576108).
文摘Corrosion and electrochemical behavior of 316L stainless steel was investigated in the presence of aerobic iron-oxidizing bacteria IOB and anaerobic sulfate-reducing bacteria SRB isolated from cooling water systems in an oil refinery using electrochemical measurement, scanning electron microscopy SEM and energy dispersive atom X-ray analysisEDAX. The results show the corrosion potential and pitting potential of 316L stainless steel decrease distinctly in the presence of bacteria, in comparison with those observed in sterile medium under the same exposure time. SEM morphologies have shown that 316L stainless steel reveals no signs of pitting attack in the sterile medium. However, micrometer-scale corrosion pits were observed on 316L stainless steel sur- face in the presence of bacteria. The presence of SRB leads to higher corrosion rates than IOB. The interactions between the stainless steel surface, abiotic corrosion products, and bacterial cells and their metabolic products in- creased the corrosion damage degree of the passive film and accelerated pitting propagation.
文摘Iron toxicity is a major stress to rice caused by a high concentration of reduced iron, in the soil in many lowlands worldwide. To reduce iron toxicity in the West African lowlands, an investigation was performed at the site of the University of Ouagadougou, in pots containing an iron toxic soil from the Kou Valley (West of Burkina Faso). The experiment objective was to study the effect of mineral fertilizer on Iron Reducing Bacteria (IRB) dynamics and activity during rice cultivation, iron accumulation in rice plant and rice biomass yield under iron toxicity conditions. BOUAKE-189 and ROK-5 rice varieties, sensitive and tolerant to iron toxicity, respectively, were used for the experiment. The pots were amended with chemical fertilizers (NPK + Urea and NPK + Urea + Ca + Mg + Zn complex). Control pots without fertilization were prepared similarly. The kinetics of IRB and ferrous iron content in soil near rice roots were monitored throughout the cultural cycle using MPN and colorimetric methods, respectively. The total iron content was evaluated in rice plant using spectrometric method. Data obtained were analyzed in relation to fertilization mode, rice growth stage and rice yield using the student’s t-test and XLSTAT 2014 statistical software. The experiment revealed that NPK + Urea and NPK + Urea + Ca + Mg + Zn fertilization, decreased significantly (p < 0.0001) the number of IRB in the soil for BOUAKE-189 rice varieties. In most pots, highest IRB densities and ferrous iron content in soil were recorded from rice tillering and flowering to maturity stages, indicating that rice plants promoted microbial processes and iron reduction in soil. From the study, the NPK + Urea amendment decreased significantly ferrous iron content (p < 0.0001) in soil near BOUAKE-189 and ROK-5 rice varieties roots relatively to control pots. However, NPK + Urea + Ca + Zn + Mg amendment increased significantly ferrous iron content (p < 0.0001) in the soil near roots, Fe accumulation in plant biomass and rice yield for the two rice varieties.
基金Project(No.IR021-00-0129-00)supported by the international Rice Research Institute (IRRI), Los Banos,Philippines.
文摘Field and greenhouse experiments were conducted to investigate the effects of cropping season, nitrogen fertilizer input and aerated fallow on the dynamics of phenol degradihg-iron reducing bacteria (PD-IRB) in tropical irrigated rice (Oryza sativa L.) systems. The PD-IRB population density was monitored at different stages of rice growth in two cropping seasons (dry and early wet) in a continuous annual triple rice cropping system under irrigated condition. In this system, the high nitrogen input (195 and 135 kg N ha-1 in dry and wet seasons, respectively) plots and control plots receiving no N fertilizer were compared to investigate the effect of nitrogen rate on population size. The phenol degrading-iron reducing bacteria (PD-IRB) were abundant in soils under cropping systems of tropical irrigated rice. However, density of the bacterial populations varied with rice growth stages. Cropping seasons, rhizosphere, and aerated fallow could affect the dynamics of PD-IRB. In the field trial, viable counts of PD-IRB in the topsoil layer (15 cm) ranged between 102 and 108 cells per gram of dry soil, A steep increase in viable counts during the second half of the cropping season suggested that the population density of PD-IRB increased at advanced crop-growth stages. Population growth of PD-IRB was accelerated during the dry season compared to the wet season. In the greenhouse experiment, the adjacent aerated fallow revealed 1-2 orders of magnitude higher in most probable number (MPN) of PD-IRB than the wet fallow treated plots. As a prominent group Of Fe reducing bacteria, PD-IRB predominated in the rhizosphere of rice, since maximum MPN of PD-IRB (2.62×108 g-1 soil) was found in rhizosphere soil. Mineral N fertilizer rates showed no significant effect on PD-IRB population density.