Softening and Melting Behavior of Mixed Burden for Oxygen Blast Furnace

 The behaviors of mixed burden in the cohesive zone of oxygen blast furnace were studied by softening and melting tests, and the influence of reducing gas and burden basicity on the softening and melting behaviors of mixed burden was also investigated. The results indicated that the softening range became wide, however, the melting range narrowed sharply in the atmosphere of oxygen blast furnace. The permeability of burden in the oxygen blast furnace was obviously improved comparing with the conventional blast furnace. In addition, the content of sulphur in the dripping iron of oxygen blast furnace was much lower than that of conventional blast furnace, however, the content of carbon increased. An optimum basicity of burden, which could lead to the appearance of the narrower melting range and better permeability of burden, was obtained in the atmosphere of oxygen blast furnace.     

Reduction of oxide scale on hot-rolled steel by hydrogen at low temperature

This study was carried out with an intention to remove the oxide scale on hot-rolled steel by gaseous reduction instead of traditional acid pickling method with an aim to reduce the pollution. The reduction of iron oxide scale by hydrogen–argon mixture was studied by thermogravimetric tests in the temperature range of 370–550 °C. The rate controlling process was discussed according to the Avrami–Erofe'ev equation generalized method. The analysis suggests that the reduction of scale is controlled by two- and/or three-dimensional growth of nuclei in the whole temperature range investigated. The apparent activation energy exhibit a sudden decrease from 78.8 to 31.8 kJ/mol at temperature higher than 410 °C. Morphological structure of the reduced scale was investigated by scanning electron microscope.     

Approximative model reconstruction of cascade systems

This letter considers how to approximately reconstruct a cascade system from a given unstructured system estimate. Many system identification methods, including subspace methods, provide reliable but generally unstructured black-box models. The problem we consider is how to find cascade systems that are close to such black-box models. For this, we use model matching techniques and optimal weighted Hankel-norm approximation to obtain accurate low-order cascade systems. We show that it is possible to bound the reconstruction error in terms of an error tolerance parameter and weighted Hankel singular values. The suggested methods are illustrated on both a numerical example and a real double tank system with experimental data.     

北方地区绿色建筑行动纲要

我国北方地区城市建筑约占全国建筑总量的26%,但建筑能耗却占到全国的40%~50%,因此,北方地区推行绿色建筑对节能减排意义重大。本文从选址与节地、供热计量、绿色建筑激励政策等十个方面阐述北方地区绿色建筑行动纲要。     

Effects of embedding direct reduction followed by magnetic separation on recovering titanium and iron of beach titanomagnetite concentrate

Embedding direct reduction followed by magnetic separation was conducted to fully recover iron and titanium separately from beach titanomagnetite(TTM).The influences of reduction conditions,such as molar ratio of C to Fe,reduction time,and reduction temperature,were studied.The results showed that the TTM concentrate was reduced to iron and iron-titanium oxides,depending on the reduction time,and the reduction sequence at 1 200°C was suggested as follows:Fe_(2.75)Ti_(0.25)O_4→Fe_2TiO_4→FeTiO_3→FeTi_2O_5.The reduction temperature played a considerable role in the reduction of TTM concentrates.Increasing temperature from 1 100 to 1 200°C was beneficial to recovering titanium and iron,whereas the results deteriorated as temperature increased further.The results of X-ray diffraction and scanning electron microscopy analyses showed that low temperature(≤1 100°C)was unfavorable for the gasification of reductant,resulting in insufficient reducing atmosphere in the reduction process.The molten phase was formed at high temperatures of 1 250-1 300°C,which accelerated the migration rate of metallic particles and suppressed the diffusion of reduction gas,resulting in poor reduction.The optimum conditions for reducing TTM concentrate are as follows:molar ratio of C to Fe of 1.68,reduction time of 150 min,and reduction temperature of 1 200°C.Under these conditions,direct reduction iron powder,assaying 90.28 mass%TFe and 1.73 mass% TiO_2 with iron recovery of 90.85%,and titanium concentrate,assaying 46.24mass% TiO_2 with TiO_2 recovery of 91.15%,were obtained.     

Effects of Al contents on microstructure and properties of hot-dip Zn-Al alloy coatings on hydrogen reduced hot-rolled steel without acid pickling

A new hot-dip galvanizing method was employed on hot-rolled low carbon steel. The effects of Al contents on microstructure, micro-hardness and corrosion resistance of Zn-Al alloy coatings were systematically investigated. Phase composition, microstructure and element distribution in Zn-Al alloy coatings were analyzed using X-ray diffraction (XRD) and electron probe micro analysis (EPMA), respectively. It is found that Al content (0. 6–6. 0 wt. %) in galvanizing zinc affects surface quality and adhesion between coatings and matrix in the newly developed method. In addition, with increasing Al content, micro-hardness significantly increased due to the increase in Zn-Al eutectoid phases. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) also revealed that increase in Al plays a noticeable role in improving the corrosion resistance of Zn-Al alloy coatings.     

Key factors affecting nickel recovery during the segregation of laterite ores

The segregation process as applied to nickel laterite ores involves the formation of gaseous nickel and iron chlorides which are subsequently reduced to form ferronickel on the surface of a solid carbon reductant. A fundamental study of the process has been carried out using limonite, nontronite and garnierite ores. The study highlighted the significant impacts that ore mineralogy and carbon addition have on the amount of nickel which is segregated rather than retained within the ore due to in situ reduction. These important aspects affecting nickel recovery and the success of the process are discussed in this paper.     

城市污水余热的再利用与实践

城市污水余热是城市中理想的新能源，因此对以城市污水余热为冷热源的能源系统进行优化设计及深入研究意义重大。以青岛麦岛示范项目为例，通过对该项目的污水源能源区域中心四年来的运营情况进行投资回报与节能效果的分析。为城市污水源热泵技术的推广提供了一种方案参考及数据支持。     

Electrochemical performance of reduced graphene oxide in Spiro‐(1, 1')‐bipyrrolidinium tetrafluoroborate electrolyte

This paper investigates the relationship between structure and electrochemical performance of reduced graphene oxide (RGO) prepared via heat treatment and chemical reduction method. Structure and morphology of RGO was characterized by means of Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction and Brunauer–Emmett–Teller. Electrochemical performance of RGO electrode supercapacitor was investigated in the organic electrolyte by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance. The results show heat treatment RGO has high graphitization degree, less surface oxygen‐containing groups, good charge–discharge efficiency and stable life cycle. The chemical reduced RGO has single‐graphene structure, high specific surface area, high specific capacitance and low internal resistance. The ascorbic acid reduction RGO exhibits good comprehensive electrochemical performance: Its specific capacitance was 220.7 F g^?1, internal resistance was 3.0 Ω and charge–discharge efficiency was 97.0% after 2000 cycles of charging/discharging tests. Copyright © 2016 John Wiley & Sons, Ltd.