Leaching of the fine fraction of the argon oxygen decarburization with lance (AOD-L) sludge for the preferential removal of iron

The fine fraction of the argon oxygen decarburization with lance (AOD-L) sludge is a hazardous waste generated by the stainless steel industry which is normally disposed in landfills. Due to the relative high content of Fe, Cr and Ni as well as its low granulometry, a hydrometallurgical route based on sequential leaching steps is being investigated to treat it. In this paper, an attempt made to remove Fe from the sludge and concentrate Cr and Ni in the solid is highlighted. Leaching was carried out at atmospheric pressure using H(2)SO(4) and HCl at varying temperature (25, 40, 55 and 70 degrees C) and acid concentration (3, 6 and 12%, v/v). For both acids, leaching rate increased with temperature and acid concentration, and higher dissolutions of Fe and Ni were obtained in comparison with that of Cr. HCl was found more selective for Fe over Ni and Cr. The content of Fe was reduced nearly 50% (w/w) at 70 degrees C and HCl 12% (v/v), while Cr remained mostly in the solid; however, around 40% (w/w) of Ni was dissolved and it may hinder such leaching step in the studied route. The study points out that total metal leaching of sludge under high temperature and pressure conditions must be considered.     

Vacuum oxygen decarburization (VOD) of stainless steel

High costs for vacuum generation and maintenance can be overcome by replacing steam ejector pumps with mechanical vacuum pumps, initially for the vacuum degassing (VD) process but later also for the vacuum oxygen decarburization (VOD) process. Initial concerns about the technical suitability of mechanical pumps for vacuum processing of large heat weights have proven unfounded. There is no real technical upper limit. With detailed knowledge about the vacuum process mechanical vacuum pumps can be successfully engineered for any heat weight where a steam ejector pump would previously have been selected. In fact, suction speed of mechanical vacuum pumps can be ideally controlled to fit the various phases of vacuum processing. This article will show how mechanical vacuum pumps contribute to significant cost reduction and to the possibility of automation of decarburisation, thereby achieving better process control.     

钢铁行业对制氧机的选型要求

本文阐述了钢铁行业对制氧机选型的技术要求和配套制氧机的工艺特点 ,介绍了配套制氧机的具体参数 ,可供相关单位的项目方案论证、初步设计时参考。     

Characterization of the supercontinuum radiation generated by self-focusing of few-cycle 800 nm pulses in argon

Self-focusing of few-cycle pulses in atmospheric-pressure argon results in a supercontinuum which differs remarkably from the case of longer pulses: under single-filament conditions it extends to 200 nm and 250 nm with 6 fs and 10 fs pulses, respectively; the radiation, including the shortest wavelengths, is collimated and shows no conical emission. The short-wavelength part is intrinsically at least as short as the incoming fundamental pulse. These features make the few-cycle supercontinuum attractive as a source of widely tunable 10 fs pump pulses for spectroscopic applications. We present extensive experimental results including the dependence of the spectrum on pulse energy, duration and chirp, filament length, gas pressure and a comparison with nitrogen and air. We discuss them and other features including the role of the third harmonic and identify the conditions required to get a single highly stable filament. We also present a model, based on self-guiding, which predicts useful scaling rules.     

6000m~3/h制氧机的噪声治理

主要介绍了分子筛吸附流程 60 0 0m3/h制氧机组空压机、氧压机等的噪声防治措施和效果 ,并提出了相应的建议     

Characterization of low mole fraction In-doped-ZnO/Si (111) heterostructure grown by pulsed laser deposition

In-doped ZnO films with low mole fraction (0.1, 0.3, 0.6 at.%) were prepared on p-Si (111) at 600 °C by the pulsed laser deposition (PLD). The effect of composition on structures, optical and electrical properties was studied by X-ray diffraction, atomic force microscopy, photoluminescence, and the Hall Effect measurement system. In-doped ZnO film has (101) preferred orientation and UV emissions of ZnO:In films were red shift with increasing In contents and there are no deep-level emissions. The lowest resistivity of 5.6 × 10^− 2 Ωcm and highest mobility of 33.1 cm²/Vs was observed at the In content of 0.3 at.%.     

Hierarchical nanostructure generated by decorating SiO(x) nanowires with CoPt nanoparticles

Silicon oxide nanowires were decorated with magnetically hard 3-5?nm-sized CoPt nanoparticles using a simple physical deposition system without any pretreatment of the nanowire surface. High curvature of the nanowire surface together with the weak metal-substrate interaction helped to maintain discrete particle morphology with spherical shapes during deposition. The weak interaction also allowed the preferential nucleation of the deposited film on the pre-existing particles so that the film deposition can be repeated in order to increase the particle size without significantly altering the particle morphology. We expect that this method can be easily extended to create other metal nanoparticle-decorated nanowires.     

Crystal habit and crystal structure of fine chromium particles: An electron microscope and electron diffraction study of fine metallic particles prepared by evaporation in argon at low pressures (III)

Fine Cr particles formed by evaporation in argon at low pressures were found to have well-defined crystal habits corresponding to the following solids: (i) the icositetrahedron bounded by 24 {211} planes; (ii) the rhombic dodecahedron bounded by 12 {110} planes; and (iii) the cube or the rectangular parallelepiped bounded by six {100} planes. The first two particle shapes were consistent with δ-Cr and the third with ordinary b.c.c. Cr. Re-examination of the crystal structure of δ-Cr by means of fine single crystals suggested that it was consistent with the A-15 type structure proposed by Forssell and Persson (J. Phys. Soc. Japan, 29 (1970) 1532). A disordered structure derivable from the A-15 type, reported previously by the present authors, is therefore withdrawn.     

Hopping conductivity of metal-dielectric nanocomposites produced by means of magnetron sputtering with the application of oxygen and argon ions

Testing of electrical properties of nanocomposites (Co_0,45Fe_0,45Zr_0,1)_x + (Al₂O₃)_1+x within the concentration range of 0.30 < x < 0.65, produced by means of magnetron sputtering of a target composed of stripes of metallic alloy and dielectric, has been carried out. It has been found that the studied materials contain metallic nanoparticles of a diameter ranging from 6 to 10 nm. Alternating current conduction at x < 0.50 is realized by hopping mechanism while at x > 0.50 metallic conductivity is observed.The obtained results have been analyzed using a model of hopping conductivity in the egime developed earlier. This analysis allowed to extract dependences of activation energy ΔE_τ and times τ in a hopping regime after isochronous (15 min) thermal annealings within the range from 293 K to 673 K.     

Effects of oxygen to argon ratio on Ba(Zr0.2Ti0.8)O3 thin films prepared by RF magnetron sputtering

Ba(Zr_0.2Ti_0.8)O₃ (BZT) thin films were deposited on Pt/Ti/LaAlO₃ (001) substrates by radio-frequency magnetron sputtering at different O₂/Ar mixing ratios. As the O₂/Ar ratio increased (1/4–4), the preferred orientation evolved from (00l) to (111). The grain size and the surface roughness increased, and the ferroelectric properties improved with increasing O₂/Ar ratio. The BZT thin films deposited under oxygen-rich atmosphere (O₂/Ar = 4) had larger dielectric constant (443) and tunability (44%), while the BZT films deposited under argon-rich atmosphere (O₂/Ar = 1/4) had a lower loss tangent (0.016).     

Removal of surface contamination and self-assembled monolayers (SAMs) from silver (Ag) nanorod substrates by plasma cleaning with argon

Surface contamination of surface-enhanced Raman (SERS)-active metallic substrates has been a limitation to the utility of SERS as an analytical technique, potentially affecting surface coverage, spectral reproducibility, and analytical limits of detection. We have developed a simple and versatile cleaning method for SERS-active Ag nanorod arrays that consists of a short (4 min) exposure of the substrate to an Ar(+) plasma in a low-pressure environment. The findings presented here demonstrate that this cleaning procedure essentially eliminates organic background contamination. This procedure works equally well for self-assembled monolayers of thiolates that strongly adsorb onto Au and Ag surfaces. For SERS-active surfaces composed of arrays of Ag nanorods prepared by oblique-angle vapor deposition, we investigated the (1) Raman band intensities, (2) nanorod morphology via scanning electron microscopy, and (3) surface hydrophobicity via static contact angle measurements, as a function of exposure time of the Ag nanorods to the Ar(+) plasma. Short (4 min) exposure to Ar(+) plasma eliminated background contamination but decreased the observed SERS intensity for re-adsorbed analytes by approximately a factor of 2 while leaving the nanorod morphology essentially unchanged. Prolonged exposure to Ar(+) plasma (>10 min) resulted in substantial morphological changes of the Ag nanorod lattice and led to a decrease in the observed SERS intensities by a factor of 10. The results presented here suggest that Ar(+) plasma cleaning is an efficient process for removing carbonaceous and organic contamination as well as thiolate monolayers from SERS-active Ag surfaces, as long as the plasma conditions and exposure times are carefully monitored.     

Elimination of Cu(II) toxicity by powdered waste sludge (PWS) addition to an activated sludge unit treating Cu(II) containing synthetic wastewater

Copper(II) ion toxicity onto activated sludge organisms was eliminated by addition of powdered waste sludge (PWS) to the feed wastewater for removal of Cu(II) ions by biosorption before biological treatment. The synthetic feed wastewater containing 14 or 22 mgl(-1) Cu(II) was mixed with PWS in a mixing tank where Cu(II) ions were adsorbed onto PWS and the mixture was fed to a sedimentation tank to separate Cu(II) containing PWS from the feed wastewater. The activated sludge unit fed with the effluent of the sedimentation tank was operated at a hydraulic residence time (HRT) of 10h and sludge age (SRT) of 10 days. To investigate Cu(II), COD and toxicity removal performance of the activated sludge unit at different PWS loadings, the system was operated at different PWS loading rates (0.1-1 gPWSh(-1)) while the Cu(II) loading rate was constant throughout the operation. Percent copper, COD and toxicity removals increased with increasing PWS loading rate due to increased adsorption of Cu(II) onto PWS yielding low Cu(II) contents in the feed. Biomass concentration in the aeration tank increased and the sludge volume index (SVI) decreased with increasing PWS loading rate due to elimination of Cu(II) from the feed wastewater by PWS addition. PWS addition to the Cu(II) containing wastewater was proven to be effective for removal of Cu(II) by biosorption before biological treatment. Approximately, 1 gPWSh(-1) should be added for 28 mgCuh(-1) loading rate for complete removal of Cu(II) from the feed wastewater to obtain high COD removals in the activated sludge unit.     

Characterization of nanostructured surfaces generated by reconstitution of the porin MspA from Mycobacterium smegmatis

Nanostructures with long-term stability at the surface of gold electrodes are generated by reconstituting the porin MspA from Mycobacterium smegmatis into a specially designed monolayer of long-chain lipid surfactant on gold. Tailored surface coverage of gold electrodes with long-chain surfactants is achieved by electrochemically assisted deposition of organic thiosulfates (Bunte salts). The subsequent reconstitution of the octameric-pore MspA is guided by its extraordinary self-assembling properties. Importantly, electrochemical reduction of copper(II) yields copper nanoparticles within the MspA nanopores. Electrochemical impedance spectroscopy, reflection electron microscopy, and atomic force microscopy (AFM) show that: 1) the MspA pores within the self-assembled monolayer (SAM) are monodisperse and electrochemically active, 2) MspA reconstitutes in SAMs and with a 10-nm thickness, 3) AFM is a suitable method to detect pores within SAMs, and 4) the electrochemical reduction of Cu2+ to Cu0 under overpotential conditions starts within the MspA pores.     

Clarified sludge (basic oxygen furnace sludge) – an adsorbent for removal of Pb(II) from aqueous solutions – kinetics, thermodynamics and desorption studies

The basic oxygen furnace waste generated in steel plant has been used as a low cost adsorbent for the removal of Pb(II) from aqueous solution. The effect of pH, adsorbent dosage, initial metal ion concentration, contact time and temperature on adsorption process was studied in batch experiments. Results of the equilibrium experiments showed that the solution pH was the key factor affecting the adsorption characteristics. Optimum pH for the adsorption was found to be 5 with corresponding adsorbent dosage level of 5 g/L. The equilibrium was achieved within 1 h of contact time. Kinetics data were best described by pseudo second order model. The effective particle diffusion coefficient of Pb(II) is the order of 10⁻¹⁰ m²/s. The maximum uptake was 92.5 mg/g. The adsorption data can be well fitted by Freundlich isotherm. The result of the equilibrium studies showed that the solution pH was the key factor affecting the adsorption. External mass transfer analysis was also carried out for the adsorption process. The thermodynamic studies indicated that the adsorption is spontaneous and endothermic. The sorption energy (10.1745 kJ/mol) calculated from Dubinin–Radushkevich isotherm indicated that the adsorption process is chemical in nature. Desorption studies were carried out using dilute mineral acids to elucidate the mechanism of adsorption. Application studies were carried out considering the economic viewpoint of wastewater treatment plant operations.     

工作气压对磁控溅射ZAO薄膜性能的影响

工作气压在ZnO∶Al(ZAO)薄膜制备过程中是一个重要的工艺参数,直接决定着薄膜的性能。本文利用中频交流磁控溅射方法,采用氧化锌铝(ZnO与Al2O3的质量比为98∶2)陶瓷靶材,在基体温度为250℃,工作气压范围为0.2～8.0Pa条件下,制备了ZAO薄膜。利用X射线衍射仪和原子力显微镜对薄膜的结构和形貌进行了分析和观察,利用分光光度计和霍尔测试仪测量了薄膜的光学和电学性能,研究了制备薄膜时不同的工作气压(氩气压力PAr)对薄膜的结构、形貌、光学性能和电学性能的影响。结果表明:随着工作气压的增加,薄膜的电阻率先略有下降然后上升,相应地,载流子浓度和迁移率先略有上升然后下降,而可见光谱平均透过率保持在80%以上。当基体温度为250℃,氩气压力为0.8Pa时,薄膜的电阻率最低,为4.6×10-4Ω·cm,方块电阻为32Ω时,在范围为490～600nm的可见光谱内的平均透过率可达90.0%。     

Analysis of stainless steel samples by energy dispersive X-ray fluorescence (EDXRF) spectrometry

A simple method for the analysis of stainless steel samples is presented which is based on radioisotope excited energy dispersive X-ray fluorescence (EDXRF) spectrometry and does not require any type-standards. Both absorption and enhancement effects have been taken into account in the fundamental parameter method for quantitative analysis and an iterative approach is followed for calculation of concentrations in steel samples. Non-linear least square fitting (NL-LSF) procedures have been used to determine accurately the fluorescent peak intensities. The method has been tested by analysing several CRM standard reference samples and 304 and 316 steel samples assuming as unknown. The EDXRF results have also been compared with the results of analysis of same samples by vacuum emission spark spectrometry (VES). Obtained values for concentration in steel samples match quite well with their certified values.     

Effects of nickel(II) addition on the activity of activated sludge microorganisms and activated sludge process

The effects of Ni(II) in a synthetic wastewater on the activity of activated sludge microorganisms and sequencing batch reactor (SBR) treatment process were investigated. Two parallel lab-scale SBR systems were operated. One was used as a control unit, while the other received Ni(II) concentrations equal to 5 and 10 mg/l. The SBR systems were operated with FILL, REACT, SETTLE, DRAW and IDLE modes in the time ratio of 0.5:3.5:1.0:0.75:0.25 for a cycle time of 6 h. The addition of Ni(II) into SBR system caused drastically dropped in TOC removal rate (k) and specific oxygen uptake rate (SOUR) by activated sludge microorganisms due to the inhibitory effects of Ni(II) on the bioactivity of microorganisms. The addition of 5 mg/l Ni(II) caused a slight reduction in TOC removal efficiency, whereas 10 mg/l Ni(II) addition significantly affected the SBR performance in terms of suspended solids and TOC removal efficiency. Termination of Ni(II) addition led to almost full recovery of the bioactivity in microorganisms as shown in the increase of specific oxygen uptake rate (SOUR) and SBR treatment performance.     

Detection of reactive oxygen species (ROS) generated by TiO2(R), TiO2(R/A) and TiO2(A) under ultrasonic and solar light irradiation and application in degradation of organic dyes

In the present work, the rutile, anatase and mixed (rutile and anatase) crystal phase TiO₂ powders were irradiated by ultrasound and solar light, respectively, and the generation of reactive oxygen species (ROS) were detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). The DPCO can be extracted by the mixed solvent of benzene and carbon tetrachloride and the extract liquors display an obvious absorption peak around 563 nm. In addition, the influences of (ultrasonic or solar light) irradiation time, TiO₂ addition amount and DPCI concentration on the quantities of generated ROS were also reviewed. The kinds of generated ROS were determined by using several radical scavengers. At last, the researches on the sonocatalytic and photocatalytic degradation of several organic dyes were also performed. It is wished that this paper might offer some important subjects for broadening the applications of sonocatalytic and photocatalytic technologies.     

Studies on adsorption, desorption and biodegradation of pentachlorophenol by the anaerobic granular sludge in an upflow anaerobic sludge blanket (UASB) reactor

PCP-degrading anaerobic granular sludge could be formed in an upflow anaerobic sludge blanket (UASB) reactor that was seeded with anaerobic sludge acclimated to chlorophenol. When hydraulic retention time (HRT) was 20-22 h and PCP loading rate was 200-220 mgL(-1)d(-1), the wastewater containing 170-180 mgL(-1) PCP could be treated effectively in UASB reactor, and PCP removal rate reached up to 99.5%. PCP adsorption and desorption by anaerobic granular sludge follow Freundlich isothermal equation and part of adsorption capacity was not reversible. And the isothermal equation could well describe the variation law of PCP adsorption and desorption by anaerobic granular sludge. The results indicated that the principal removal mechanism of PCP was biodegradation by anaerobic granular sludge, but not adsorption or volatilization.     

Transport properties of graphene films grown by thermodestruction of SiC (0001) surface in argon medium

We present the results of investigations of the transport properties of graphene films obtained by thermodestruction of a 4H-SiC (0001) surface in argon. The charge-carrier concentration in the graphene layer was within 7 × 10¹¹–1 × 10¹² cm^–2, and the maximum mobility of electrons approached 6000 cm²/(V · s). The achieved parameters of mobility are close to theoretical values calculated for graphene films with intrinsic conductivity on the Si face of SiC at Т = 300 К in the absence of intercalated hydrogen.