Computational modelling of shear-layer instabilities and vortex formation in DC plasma arcs

The direct-current plasma arc is the principal heating and stirring element in plasma arc furnaces. The arc is a highly dynamic system operating at very short time scales (milliseconds or less). This dynamic behaviour can be understood as the combination of several modes of instability acting together. These modes can include fluid dynamic/shear layer instabilities, near-electrode instabilities resulting from steep local temperature gradients and other electrode surface effects, or helical/twisting instabilities resulting from the magnetic field generated in one part of the arc column exerting a force on another.Computational magneto-hydrodynamic models of the arc which are able to reproduce the highly transient behaviour of the system are developed to study certain dynamic modes – in particular, the formation and evolution of axisymmetric vortices and shear layer instabilities in the arc jet. Results from this work are then compared to qualitative data from high-speed photographic imaging of large plasma arcs (up to 3 kA current).     

Pyrometallurgically regenerated LiMn2O4 cathode scrap material and its electrochemical properties

Recycling cathode materials from lithium-ion battery scraps can play a significant role in reducing environmental contamination and resource depletion. In this study, we employed pyrometallurgical techniques to regenerate LiMn₂O₄ cathode materials from recovered cathode scraps. First, the binder was removed under optimal conditions by a heating and stirring method to maximize the dissolution rate of the cathode scrap materials. Next, inductively coupled plasma spectroscopy was used to define the Li and Mn contents, and finally, the LiMn₂O₄ cathode material was regenerated by a pyrometallurgical method. After calcination under the optimum conditions of 500 °C for 12 h, electrochemical performance testing revealed obvious charge and discharge platforms in the charge/discharge curves; further, a high first-cycle discharge capacity was observed at 136.6 mAh·g^-1 (3.0–4.3 V and 0.1 C), which decreased to 93 mAh·g^-1 after 50 cycles. This process is low-cost and environmentally friendly, with the potential for recovering other cathode scrap materials.     

有色金属工业自动化仪表现状及需求

本文介绍了有色金属工业检测仪表现状及不足，提出一些需要解决的问题。     

Effect of micro-pores on cracks formation in metallurgical coke

The relationships of micro-pores and cracks in metallurgical coke have been investigated by optical microscope and field emission scanning electron microscope, using surface section samples. The pores have circular, elliptical and irregular shapes with smooth outlines, formed during the thermoplastic stage of the coking process. They often associate with connecting cracks between neighbouring pores. In case of elliptical pores, the connecting cracks are usually oriented along the longer axis of the pore. The connecting cracks can be developed between the pores, depending on their size and the distance between them. The coke with a large number of small pores rather than with a small number of larger pores will have lower strength due to the increased amount of connecting cracks. When compared with circular pores, elliptical and flattened pores have a lower ability to resist load pressure. Nano-sized pores have polygonal outlines, indicating an ‘explosion’-type formation in the solidified matrix.     

镍矿的处理工艺现状及进展

镍矿是国民经济中一种重要的金属矿产资源,随着经济的发展,人们对镍矿资源的消耗呈逐年上升趋势。目前所查明的镍矿资源中,有近70%的镍矿资源都是硫化镍矿,近30%的镍矿资源属于红土镍矿。随着镍矿资源查明储量的下降,其镍矿资源的综合利用受到越来越多国家的重视。在查阅大量文献的基础上,简要的论述了镍矿资源的总体情况,概述了硫化镍矿常规的处理方法,以及近年来浮选法的一些实际应用及发展。最后,介绍了当前状况下红土镍矿的火法和湿法处理工艺现状及进展,以及一些其他处理镍矿石的方法。为以后镍矿石资源的综合利用和处理工艺的研究提供了一定的参考价值。     

Investigating the effect of slag bath conditions on the existence of multiphase emulsion zones in PGM smelting furnaces using computation fluid dynamics

The presence of chrome in electric arc furnaces smelting platinum group metals (PGM’s) has a number of potentially negative consequences. In cases where the slag chrome content is above the saturation limit the existence of near-stagnant conditions near the slag/matte interface increases the risk of chromite spinels settling and consolidating into a “mushy layer”, a three-phase suspension of slag, chromite and matte. The hold-up of matte above the elevation of the slag/matte interface can lead to the attack of freeze linings and copper cooling elements potentially causing failures of the furnace lining and significant downtimes as well as major safety risks. This paper investigates the relationship between typical furnace operating parameters and the behavior of the slag bath with respect to the formation of the “mushy” layer at the slag/matte interface using computational fluid dynamics (CFD). The extent of the potential “mushy” layer is seen to increase with decreasing electrode immersion and furnace power. Electrode immersion is, however, a considerably stronger driver is this regard. The CFD modelling results have aided in selecting appropriate furnace electrode immersion/power combinations intended to minimize “mushy” layer formation.     

A new infrared camera-based technology for the optimization of the Waelz process for zinc recycling

Today, the Waelz process using a rotary kiln is the best technology available for the pyro-metallurgical treatment of zinc-bearing residues. However, this process will only result in a good zinc recovery, if the temperature distribution in the kiln and the rheological behavior of the material are controlled. Unfortunately, these properties cannot be measured with conventional sensors. In this paper, an image processing system for the Waelz kiln process will be presented, which calculates the relevant process information from infrared camera images in an online manner. It uses a custom-built infrared camera with a spectral filter at 3.9 μm, which provides for a detailed insight into the kiln. The information that is calculated by the image processing system, including temperature distributions of the material, repose and filling angles, is directly used for closed loop control. The system presented has been in operation at an industrial plant in Germany for about 2 years.     

废旧电子电器产品中贵金属的回收利用概况

本文介绍目前国内外对废旧电子电器的回收处理现状,并概述了现今所应用的回收废旧电子电器产品中贵金属的主要方法和新工艺。