Processing of copper-electrolyte slimes: Evolution of technology

The slime formed during the electrical refining of copper is a valuable multicomponent product. The methods for processing it are determined by its composition and depend on the form of its precious metals, and that of its selenium and tellurium. We analyze the advantages and disadvantages of the main techniques used for processing copper-electrolyte slimes. The prevailing trend in the development of modern slime production is improving hydrometallurgic techniques while eliminating smelting for silver-gold alloys and reducing toxic emissions into the environment.     

铜阳极泥复合浸出渣选择性分离硒过程热力学分析

铜阳极泥复合浸出渣是铜阳极泥采用复合浸出砷锑铋后的产物,采用硫酸化焙烧选择性分离硒。针对其含硒物质在选择性分离过程中的反应历程不明晰,本文利用Factsage数据库中相关热力学数据及Equilib平衡计算模块对含硒物质在不同温度时反应的■及反应过程平衡分析,明晰反应过程中的物相变化规律。结果表明：Cu₂Se与H₂SO₄在低温下反应生成固态Se、CuSO₄·H₂O、SO₂及H₂SO₄吸水形成H₂SO₄·H₂O;然后固态Se融化变成液态Se,同时与H₂SO₄·H₂O反应生成SeO₂、SO₂和H₂O;高温下CuSO₄·H₂O会脱水生成CuSO₄和H_2...     

Thermodynamic prediction of the eutectoid transformation temperatures of low-alloy steels

The experimental eutectoid transformation temperatures (A ₁) of low-alloy steels, as reported in the USS Atlas of I-T diagrams, have been compared to the thermodynamic predictions of a model proposed by Kirkaldy and Venugopalan. The analysis is consistent with the model prediction that Cr atoms are almost fully partitioned, while Ni and Mo atoms are scarcely partitioned, during the eutectoid transformation. This study also shows that Mn atoms are partitioned fully or partly in C-Mn, Cr-Mn, and Mo-Mn steels, while they are scarcely partitioned in Ni-Mn steels. The difference (ΔT) between the orthoequilibrium (OE) eutectoid temperature (A _e1) and the paraequilibrium (PE) eutectoid temperature (A _p1) has been investigated as a function of the content of each substitutional alloying element. The slope of ΔT increases with substitutions of Mo, Ni, Mn, Si, and Cr, with Mo having the least effect, Ni the next-greatest effect, and so on. Considering both Mn partitioning and the slope of ΔT, the equation for the prediction of A ₁ temperatures of low-alloy steels proposed by Kirkaldy and Venugopalan is modified. This new equation is in better agreement with the experimental A ₁ temperatures.     

Melting of oxidized nickel ores in a barbotage unit: I. Thermodynamic analysis of melting

The possibility of effective processing of oxidized nickel ores (ONOs) to form ferronickel in a barbotage unit (Vanyukov furnace for liquid bath melting (LBM)) is theoretically corroborated. The heat balances of the LBM processing of unreduced ONOs or the cinder preliminarily reduced in tubular kilns to form ferronickel are calculated. It is shown that deep reduction of ONOs and melting of the reduced cinder are energetically more favorable than direct melting of a slightly dried ore to form ferronickel. The proposed twostage scheme of processing of ONOs makes it possible to decrease the furnace area and the effluent gas flow. Parallel reduction and oxidation processes in the same region of a bubbled slag melt during direct melting of unreduced ore is debatable.     

Towards stiffness prediction of cellular structures made by electron beam melting (EBM)

Abstract

Additive manufacturing is a novel way of processing metallic cellular structures from a powder bed. However, differences in geometry have been observed between the CAD and the produced structures. Struts geometry has been analysed using X-ray microtomography. From the 3D images, a criterion of ‘mechanically efficient volume’ is defined for stiffness prediction. The variation of this criterion with process parameters, strut size and orientation has been studied. The effective stiffness of struts is computed by finite element analysis on the images obtained by X-ray tomography. Comparison between the predicted stiffness and the effective one tends to show that the efficient volume ratio leads to a slight underestimation of the stiffness. Finally, the effective stiffness is used at the scale of a unit cell. This can help define the build orientation and loading direction that lead to the highest stiffness.     

Effect of the sixth period elements on the melting and transformation temperatures of praseodymium: Part II. Thermodynamic analysis

A thermodynamic analysis of the praseodymium-rich alloys containing Os, Ir, Pt, Au, Hg, Tl, Pb, and Bi indicated that most of the solutes dissolved in praseodymium follow ideal solution theory over a limited range of temperatures up to 40° to 135°C below the melting point of praseodymium (or concentrations out to 3 to 8 at. pct solute). The activity coefficients, activities, and excess partial free energies were calculated for liquid praseodymium at its melting point and for β-Pr at its α to β transformation temperature. The so-calledQ parameter has also been determined for these praseodymium systems, and it was found to exhibit the usual periodic dependence on the solute metal. As a result of these analyses a method has been developed which makes it possible to calculate phase boundaries for undetermined systems. This technique is shown to be especially valuable in calculating unknown phase boundaries for lanthanide-rich alloys, but for other metal solvents this method will probably be of a lesser utility.     

Hydrogen reduction kinetics of electrometallurgical slime

The interaction of hydrogen with the zinc-containing electrometallurgical slime of the Severstal’ metallurgical works has been studied. The sequence of transformations in the slime heated to 1100°C in hydrogen or air has been established. The experimental and calculated weight losses coincide. Some of the carbonates are shown to decompose in the temperature range 300–700°C, and most iron and zinc oxides are reduced to a metal. In the temperature range 650–850°C, zinc is almost completely sublimated. At temperatures above 800°C, complex oxides are reduced and calcium and magnesium carbonates and sulfates are likely to decompose. Experimental digital data on the zinc sublimation rate are processed by the least squares method with approximating equations used in thermal analysis. The kinetics of nonisothermal zinc sublimation is comprehensively analyzed using a unique procedure developed for taking into account the background of a peak and the effect of accompanying processes. An equation for the calculation of the zinc sublimation rate under experimental conditions (fluidized bed) is given and tested.     

The measurement and prediction of the melt velocities in aturbulent,electromagnetically driven recirculating low melting alloy system

Experimental measurements are reported describing the velocity field in an inductively stirred low melting alloy. The molten metal was held in a cylindrical container, 500 mm high and having an inside diameter of 250 mm; induction stirring was supplied by a three phase coil, which provided a maximum field strength of 350 Gauss (0.035 Wb/m²). The velocities in the melt were measured by a mechanical force reaction probe and were found to range up to about 0.5 m/s. Theoretical prediction of the melt velocities was made by solving Maxwell’s equations, together with the turbulent Navier-Stokes equations, using a digital computer. The experimentally measured and theoretically predicted velocities were found to agree within about 30 pct, thus providing direct experimental proof for the validity of modelling electromagnetically driven flows using this technique.     

铜阳极泥处理生产实践

针对阳极泥成分变化及其影响，介绍了各工序优化操作条件和相应的增产措施以及实施效果。     

真空感应炉熔化期工艺优化控制

采用神经网络进行真空感应炉熔化期工艺过程的建模,利用实际工业生产数据进行仿真,并对某一钢种的熔炼工艺操作,采用遗传算法对熔化期电能的输入与合理分配进行了寻优,仿真结果表明该方法的有效性和优越性。     

降低阳极泥产出率的生产实践

由于原料日趋复杂,导致铜电解阳极泥的产出率大大超过原工艺设计值.通过采取一系列相应措施,使阳极泥产出率控制在0.7%以下,同时阳极泥金、银含量也有所提高.     

铅阳极泥处理技术的研究进展

铅阳极泥是粗铅电解精炼过程产出的一种副产物,是重要的二次资源,富含多种有价金属元素.从铅阳极泥资源中综合回收金、银等有价金属元素越来越受到重视.论文详细介绍了近年来铅阳极泥火法处理工艺、湿法处理工艺、火法-湿法联合处理工艺的研究进展,并对真空处理技术及直接制备纯物质技术进行了报道.针对云南某冶金企业高铋砷铅阳极泥的特点,作者所在课题组提出“加压氧化碱浸脱砷锑铅-熔铸粗铋合金-铋电解精炼”的处理新工艺,在分离砷锑铅的同时,实现了铋的清洁提取与金银的高度富集.结果表明:铋的回收率>98 %,锑、铅的回收率>96 %,金的回收率>99 %,银的回收率>97 %.铋电解阳极泥中金、银含量从铅阳极泥原料中的22 g/t、3 595 g/t分别富集到201 g/t、31 270 g/t.      

铜阳极泥处理工艺的改进实践

分析了金昌冶炼厂铜阳极泥处理工艺存在的问题及对生产的影响,介绍了所采取的改进措施及工艺改进后取得的效果.     

碲阳极泥的控制及处理方法

碲电积精炼过程产生碲阳极泥,其碲含量占到总碲量的3％ ～ 20％,导致碲的直收率降低.碲阳极泥的主要成分是高碲酸钠,由阳极产生的氧气将部分亚碲酸钠氧化形成的难溶疏松颗粒状或片状结晶,大部分沉降到槽底,少量粘附在阴极板面.高价碲盐在结晶长大、沉降、粘附过程中会夹带低价态碲盐,加大碲的损耗.采取改变阳极结构、在阳极套涤纶布...     

稀有金属真空熔炼熔速控制的研究

针对电弧炉的不稳定性和强耦合性问题,提出一种基于模糊控制真空自耗电弧炉熔速控制方法,通过对熔速控制系统模型分析与描述、对真空自耗电弧炉熔速控制策略分析以及对模糊控制理论的研究,实现对电弧炉熔速的稳定控制,从而保证真空自耗电弧炉的稳定性运行。