Mineralogical evaluationof ladle slags at voestalpine Stahl GmbH

Abstract

A large number of steel grades are produced at voestalpine Stahl GmbH. The ladle slag must meet different requirements according to the specific steel grade. The mineralogical structure of ladle slag is highly dependent on its basicity. At a basicity of <0·8, spinels occur, and, at higher values, periclase or (Mg,Fe)-wüstite occurs, depending on the degree of slag deoxidation. At basicities between 0·6 and 1·6, calcium aluminates C₁₂A₁₇ and C₃A (C=CaO; A=Al₂O₃) are predominant. Calcium silicates C₂S and C₃S (S=SiO₂) occur throughout the basicity range, and CaO _free occurs at basicities >1·2, both depending on the SiO content. This enables the metallurgist to specifically adjust the ladle slag according to the steel grade requirements. Knowledge of the slag condition is essential in order to achieve certain metallurgical results, such as desulphurisation or degree of oxide purity.     

Investigation of factors affecting pellet strength in straight grate induration machine

Abstract

During induration in a straight grate machine, the green pellets pass through four different thermal treatments, namely drying, preheating, heating and cooling. The pellet bed is fired with downdraught firing leading to thermal gradients through the bed. Corex sludge, which is used as fuel in the pellet mix, supplies the necessary energy for uniform heating of the pellet. The physicochemical conditions, e.g. the temperature and oxygen partial pressure mainly depend on the amount of fuel incorporated in the pellet mix. As a result the percentage and the distribution of various phases in the pellets vary, leading to deviation in quality. To study the distribution of phases and their impact on cold crushing strength at different carbon levels (1·20 and 1·35%), pellets from different layers of the induration bed in an industrial straight grate were characterised. It was observed that the strength of the pellets varied from 142 to 268 kg/pellet and 128 to 245 kg/pellet across bed, with carbon 1·20 and 1·35% respectively. It was found that middle layer pellets had higher strength compared to top and bottom layers. It was observed that amount of hematite, magnetite, porosity and the pore size plays a significant role on the pellet strength. Pellets with 1·20% carbon showed better physical and microstructural properties across the pellet bed compared to pellets with 1·35% carbon.     

QoS Management by Means of Application Control

The complexity and sophistication of integratedbroadband networks call for a broad repertoire ofmanagement methods. Foreseen intensive competition ofthe communications market, and the upgrade ofend-customer's satisfaction as the focal point of anymanagement policy, raise a very important problem: howto utilize efficiently the resources of the networkwhile maintaining the Quality of Service (QoS) provided to end-users within a pre-negotiated range. Inthis paper, a QoS management architecture for multimediaapplications based on an application control scheme isproposed. Adhering to the Total Quality Management (TQM) paradigm, we let management span over theentire communication stack, the entire network(end-to-end) and the entire call duration. Applicationcontrol scheme aims to meet pre-specified QoS goals by adjusting the traffic produced by theend-user applications. The adjustment technique is basedon the notion that each multimedia session is allowed tooperate on a set of discrete application quality levels. A method for monitoring and assessingthe end-user perceived quality is presented. Themathematical problem of optimal resources allocation andan associated heuristic are specified. Finally, a specific instantiation of the introduced QoSmanagement architecture on a real testbed is describedand experimentation results are presented andevaluated.     

A neural network based model of sinter quality and sinter plant performance indices

Abstract

A prerequisite of a smooth operation of the ironmaking blast furnace is that the quality of the burden is stable. In blast furnaces where sinter is used as the (main) iron bearing material, its quality plays a crucial role in productivity and fuel economy. Simultaneously the corresponding factors must be considered for the sinter plant. The present paper studies the influence of three variables characterising the bedding piles and five sinter plant operation variables on sinter quality, sinter plant productivity, specific fuel consumption and share of cold return fines. Daily mean values for a period of five years of operation were used in the data driven modelling based on feedforward neural networks. The resulting models were found to describe the major changes in the outputs well. The input–output relations captured by the models were analysed by perturbing one input variable of the networks at a time and analysing the predicted behaviour of the outputs.     

Influence of raw material particle size on quality of pellets

Abstract

Pellet plant (4·2 MPta capacity) of JSW Steel Ltd imports iron ore fines from different mines to produce pellets for its Corex and Blast Furnace plants. The pelletisation process involves drying the ore fines to reduce the moisture content to less than 1%, grinding in open circuit ball mills to get required fineness. To produce good quality of pellets certain additives are important and limestone is employed for modifying the pellet basicity. Iron ore fines of ?10 mm size and limestone are ground together in a ball mill to get sufficient fineness for the balling process. However, as limestone is harder than iron ore fines the + 100 mesh size limestone particles is higher than required and not all the limestone is fully consumed in the reaction for melt formation. Microstructural studies were conducted under a Leica DMRX polarized microscope at different level fineness (?325# ? 56, 58 and 60%) to investigate its effect on the pellet quality. The cold crushing strength of the pellet improved from 203 to 220 kg p^?1 with increase in fineness. With increase in percentage of ?325# particle size in the ground product RDI of the pellet decreased from 13·8 to 11·9% with increased melt formation from 5 to 9%. With increase in fineness ?325# from 56 to 60% the 150 to 500 μm size pores decreased from 51·8 to 13·6%.     

Developing predictive tools for friction stir weld quality assessment

Abstract

This research programme explores predictive tools that assess friction stir weld quality in aluminium alloys through dynamic characterisation. The study focuses on the correlations between dynamic interrogations measures of friction stir welded panels with the weld energy, as welded mechanical properties and the microstructure. 7136-T76 aluminium extrusions were joined at unique weld energies, and to characterise and identify the friction stir welds through non-destructive techniques, theoretical modelling and lab scale dynamic testing were conducted to establish the correlation between the weld energy and the associated spectral characteristics of the beam (natural frequencies/mode shapes). In this non-destructive evaluation study, the modal parameters were measured and were correlated with the friction stir weld microstructure and the physical parameters of the welded components, such as axial and flexural rigidities. The viability of weld parameter identification and weld quality assessment of friction stir welding beams using dynamic interrogation techniques is demonstrated.     

Relationship between plasma arc cutting acoustic and cut quality

Abstract

The tremendous acoustic signal exiting during the plasma arc cutting process includes a lot of information about this process and has a close relation with cut quality. To investigate the relationship between the plasma arc cutting acoustic and cut quality, a number of experiments have been carried out. In the present study, cut quality by plasma arc is described by top and bottom kerf widths, bevel angle, and attached dross state, and the relationship between the evaluation items for cut quality and the SPL (sound pressure level) of the cutting acoustic is investigated in detail. It is shown that the SPL reaches a maximum as the bottom kerf width equals the diameter of the plasma arc potential core. The attached dross and kerf widths in a state of free dross obviously affect the low and high frequency components of the plasma arc cutting acoustic, respectively. These results also suggest the possibility of designing an acoustic-based monitoring system for the plasma arc cutting process.     

Signature images for arc welding fault detection

Abstract

The present work elucidates the signature image approach to welding fault detection, covering the calculation of signature image data objects from blocks of welding electrical data (voltage and current), the definition of appropriate vector operations, and the manipulation of the signatures to permit detection of welding faults. Detection of out of position welds in overlap joints is illustrated, and the relevant changes in signature features are related to the physics of the short arc welding process. Finally, it is shown how fault detection performance can be improved by optimising the way the signatures are calculated.     

LDPE工艺颗粒水系统粉尘产生的分析及应对

颗粒水系统水是高压装置挤压造粒的重要水系统,担负冷却、传输聚乙烯产品颗粒的作用,本文参照高压装置开车多年来颗粒水系统粉尘处理措施,以实际操作实际加以分析。     

啤酒用小麦蛋白质含量与制麦芽性能的关系

主要研究了蛋白质含量对于小麦芽制麦性能的影响，实验中发现；蛋白质含量与小麦的发芽力以及发芽期间β-淀粉酶和蛋白酶的活力呈显著的正相关性，与千粒重及淀粉含量呈负相关性，蛋白质含量高或太低都会对小麦芽的质量产生不利的影响，这表明蛋白质含量是评价啤酒用小麦制芽性能的核心因素之一。