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By Sue Ritz

Gold extraction has relied on coconut carbon in adsorption circuits for several decades. IXOS®, invented by 6th Wave Innovations of Salt Lake City, Utah, is a new type of adsorbent that exceeds the selectivity of carbon and improves on the mechanical properties of other available resins. IXOS selectivity against copper cyanide complexes allows it to be used in circuits that currently struggle with copper contamination. IXOS potential to eliminate or reduce the application of SART technology will expand the opportunities to exploit more complex precious metals deposits. This paper will describe the technology behind IXOS molecular imprint, its comparison to carbon adsorption in the field, and the effect of efficiency on long-term recovery from heap leach METSIM simulation software.

By J. Sofra

The quantity of copper produced by secondary material processing is increasing as metal producers look to cleaner and cheaper sources of copper. The need to smelt secondary copper more economically, to process a wide range of materials with large fluctuations in size and composition and to cope with the increasingly stringent environmental constraints have put considerable pressure on existing conventional secondary copper smelters. The Top Submerged Lance process, developed and commercialized by Ausmelt Ltd offers a low cost technology, which is particularly adapt at processing copper-bearing scrap and residues. The application of Ausmelt Technology to replace conventional secondary copper processing operations introduces potential for significant advantages in environmental performance, and improved process efficiencies through the use of cheaper hels and reductants, the high rate of metal recovery and the flexibility inherent in the technology to process various feed material types. The economical, process and environmental benefits of its application are highlighted for both the smelting and converting stages of copper production.

Jan 1, 1997

By Jesse White, Arlin Olson

"An Engineering Scale Technology Demonstration (ESTD) unit utilizing the THOR fluidized bed steam reforming technology was built and operated by Hazen Research, Inc. for the purpose of denitrating and solidifying various Department of Energy (DOE) radioactive tank waste surrogates into granular products. The ESTD offered the opportunity to investigate the operational characteristics of two fluidized beds in series to test process system designs such as those for fluidization, feeding, and product collection. Operational characteristics that were evaluated included bed attrition rate, particle growth, and elutriation; and the effects that variations in process parameters (e.g., fluidizing gas flow rate, feed composition, feed injection method, and gas distributor design) had upon these characteristics were observed. Testing of the process systems on this scale allowed for design changes to be made where the cost in time and money were significantly less by comparison to those same modifications being made on the commercial scale.IntroductionFluidized bed steam reforming (FBSR) offers a moderate temperature (620-750°C) continuous method by which various liquid wastes can be processed irrespective of whether they contain organics, nitrates, sulfates/sulfides, chlorides, fluorides, volatile radionuclides or other aqueous components. The FBSR technology has exhibited the potential to process these wastes into either a carbonate or crystalline ceramic (mineral) granular product.Pilot scale testing was performed using the THOR Treatment Technologies, LLC (ITT) FBSR process, as it offered the opportunity to evaluate multiple aspects in an environment more conducive to experimentation. Process changes and system modifications could be made faster and with less cost impact as compared with changes to an assembled commercial plant. These aspects include verification of process chemistry and kinetics, evaluation of materials of construction, equipment sizing and design, and the interactions of the systems. Evaluation of process chemistry allowed for the verification of thermodynamic and kinetic models, and was used in conjunction with these models to improve the database and modeling assumptions. It also allowed for the reevaluation of data from earlier bench scale testing with the opportunity for long-term operations. These long-term effects may include the buildup of one or more elements that results in the formation of eutectics leading to the destabilization of a fluidized bed, or the shift in particle size as a result of attrition or agglomeration. The pilot plant also provided an environment to evaluate materials of construction."

Jan 1, 2014

By Yafei Xiong, Yue Wang, Guotao Xu, Shuzhong Li, Huaiyuan Li

"The composition, properties and structure of taphole clay with high strength and friendly surrounding used in a new blast furnace with 3800 M3 volume was studied. The developed taphole clay had been applied in the blast furnace for four months, pouring times were 11-13 every day, flowing rate of hot iron was 7.5 t/min and the consumption of taphole clay was 0.49Kg per ton iron, which can make the new blast furnace attach the designed production quickly and decrease the cost of hot iron. The taphole clay is easy to be opened in the channel of hot iron which can be remained in stable shape under the corrosion of slag or hot iron, and it dose not produce poisonous smoke in yellow or dark color in the use process. The development of new taphole clay is useful to improve the work surrounding of the blast furnace.IntroductionIn the iron-making process, the taphole clay's function is filling up the taphole and protecting the formation as well as the growth of the clay in the blast furnace, maintaining the enough taphole depth; simultaneously it is easily to open a hole and knock out the clay. The taphole clay has a good performance of molten slag and hot iron resistance. The traditional taphole clay uses coal tar or carbolineum as a binder, and the performance of taphole clay is good, but it has the black and yellow poisonous smoke, which is harmful for work condition. Through the investigation on the binder's composition and poisonous performance of taphole clay, the environmental taphole clay is developed by some foreign companies, which is named the third generation product with benzene is less than 300ppm, and it has been used in European steel companies. This application of the taphole clay with high strength and environment-friendly using in 3800m3 blast furnace is introduced and the performance is discussed and analyzed in this paper."

Jan 1, 2012

By Wilson Pascheto

This paper presents results of investigations performed as part of a Root-Cause-Failure-Analysis (RCFA) of a DC smelting furnace that was brick lined with MgO-based refractories. An unusual continuous contraction of the furnace hearth was identified during operation. Cracks in the refractories were envisaged after a major shutdown of the furnace. To determine the mechanism and causes of the unusual contraction behaviour of the furnace hearth, refractory samples were taken from the furnace at different locations and subjected to different analysis including Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), QEMSCAN and Electron Probe Micro Analysis (EPMA). Creep testing of refractories under different loads (ASTM C832) was also employed to evaluate the mechanical integrity of the used bricks in comparison with the new ones. Results of the various characterisation analyses revealed that there was an interaction between refractory bricks and molten material during furnace operation, which resulted in reduced creep resistance of the MgO-based refractories. This was verified by comparing creep performance of the used brick samples and new brick samples at different temperatures and applied stresses.

By Christian Trassy, Pierre Proulx

"Inductive plasmas are now commonly used in material processing: spraying, powder synthesis, densification or spheroidization. An inductive discharge presents, in the coil region, recirculation eddies due to the Lorentz forces, resulting in an axial backflow. If the central jet is strong enough to ""pierce"" the recirculation this axial backflow disappears on the centerline, but the external layer of the injection flow is skimmed by the remaining eddy, and particulates are rejected to the discharge periphery. To avoid this disadvantage, it is common to introduce the injection pipe inside the discharge, so that its outlet is positioned after the recirculation eddy. The powders remain confined in the axial zone, to the expense of shortened residence time.In order to increase the efficiency of the particle trajectories, a double flow injector has been designed. It enables the particles to travel closer to the axis, while the outer schrouding gas is skimmed and passes through the electromagnetic eddies. This injector is made up of two concentric tubes. The powders are injected with the carrier gas in the inner tube. A schrouding gas is injected in the annular space between the inner and the outer tubes. The powder is confined to the vicinity of the axis, resulting in a more homogeneous thermal treatment.Tungsten powders have been spheroidized with and without this device. Using the double flow injection, the spheroidization yield has been increased from 70 % up to 95 %.The design of such an injection device has. been studied and improved using numerical modelling. Another useful tool, a visualisation technique described elsewhere, has been used for the experimental study, that drastically simplifies the comparison between experimental and theoretical results: injecting yttrium oxide into the discharge results in a colorful display of the 4000 K isothenn: the ""cold"" zone, below 4000, appearing as red, and the ""hot"" zone as blue. Furthermore, it is of great industrial interest since it is a very cheap and efficient way to obtain a picture of an important isotherm."

Jan 1, 1999

By Claudia Gasparrini

Uranium occurs in a variety of minerals, the more common primary ones of which are uraninite-pitchblende, coffinite and a group known as the complex multiple oxides. Identification and description of the uranium-bearing and associated minerals in ore samples may give a preliminary indication of the potential economic importance of the deposit and may also suggest initial approaches to metal extraction. The present paper reviews the common uranium minerals, describes their manner of occurrence and compares the types of deposits with which they are associated. Methods and techniques for their identification are described and their leaching characteristics discussed.

Jan 1, 1981

By Sevinc Yildirim, Cigdem Oruclus

"Metal-Porous Silicon (PS) based structures dipped in water show the direct hydrogen fuel cell behavior. The effect of the thickness of the cupper (Cu) film on the electrical properties of direct hydrogen fuel cell is studied by fabricating Cu/Porous Silicon/n-Silicon/Indium structures. PS samples were produced electrochemical etching of n-type single crystalline silicon with a resistivity of 1,25 Ocm and (111) orientation. The thin films of Cu with different thickness between 200 and 600 nm were deposited on PS surface by electron-beam technique. Investigation of the effect of Cu layer on the performance of the structure indicates that the performance parameters such as open circuit voltage (Voc) and short circuit current (Isc) strongly depend on the Cu layer thickness. It was observed that the divice with an 350 nm Cu layer exhibits the highest open circuit voltage (0,5 V), short circuit current (0,01 mA) and power density (10 W.m-2).IntroductionHydrogen is the most attractive and ultimate candidate for a future fuel and an energy carrier. Hydrogen is recognized as the environmentally desirable clean fuel of the future since it can be used directly in different types of hydrogen fuel cells [1]. In the past years, the rise in portable electronics requires the development of miniature fuel cells compatible with standard silicon micro fabrication technology. Most silicon micro-fuel cells have used the polyperfluo-rosulfonic acid membranes (Nafion R) as a proton exchange membranes (PEM) that is not really integrated with standard micro fabrication techniques [2-5]. The composite materials such as inorganicorganic hybrid materials (Nafion-silica, Nafion-borosiloxane etc) are next generation of proton conducting membrane [4-8]. But, fuel cells run on pure hydrogen gas, which can be produced with other energy resources. Hydrogen smallest atom and thus the H2 gas can leak easiliy. The application of hydrogen for power sources has been greatly restrained due to the lack of safe and convenient generation and storage methods.A kind of hydrogen fuel cells Metal-PS-Si structures used as an energy water directly. There is no need pure hydrogen. Cu-PS-Si Schottky-type fuel cells with as proton-conducting membrane and the thin-film cupper catalist and water as fuel, which are interesting for fabrication of lowcost miniature fuel cells. Generation of the open-circuit voltage and short-circuit current has been observed by Cu-PS-Si structure dipping in different hydrogen-containing solution."

Jan 1, 2014

By M. Cowling, S. Kumarl, A. W. Piper, R. A. Forsdick, C. Bailei, M. Patell

"The lead-refining process takes place in hemispherical vessels called kettles. In these kettles, lead-bullion is mixed at a certain temperature to remove impurities from the melt. This paper presents steps in a novel method for calculating vortex shape and flow field in the refining kettle using Computational Fluid Dynamics (CFD). First of all a two-dimensional axisymmetric model is used to calculate the vortex shape at the liquid-air interface. Here action of impellers and baffles are accounted for by adding source and sink terms to the appropriate momentum equations. The model includes Yolume of Fluid (YOF) method to predict the shape of interface deformation, i.e. vortex. This strategy reduces the computationally intensive three-dimensional transient simulations to a more efficient two-dimensional model. The calculated vortex shape is then used to regenerate a full three-dimensional grid. This grid is used to carry out steady-state simulation using the standard multiple-reference-frame method of impeller-fluid-baffle interaction within the commercial code Fluent. Simulation results for both stages of the development are compared with experimental data.IntroductionOne of the most important steps in Lead Refining process is impeller stirred mixing of Lead Bullion in hemispherical vessels. During this process, the melt is treated with one or more reagents in order to remove impurity elements such as copper, antimony, silver and bismuth. These impurities react selectively with the reagents and float to the melt surface in the form of a powdery layer, which is then skimmed for further processing. Figure-! shows (a) the lead refining kettle and (b) the schematic representation of involved flow pattern. Stirring of the lead bath using specific impeller designs, which creates a central vortex, provides a mechanism for draw-down and dispersion of the buoyant reactants. Clearly, effective control of the impeller generated vortex and flow pattern is crucial to achieving efficient operating conditions."

Jan 1, 2001

By E. B. Freidina

We have investigated a new electrochemical process for preparing lead-calcium alloys. Calcium metal, reduced fiom a molten chloride mixture, forms an alloy with liquid lead cathode. The addition of calcium carbonate to conventional CaC12-NaCl electrolyte enables us to avoid chlorine production on the anode and replace it with oxygen and carbon dioxide. The ternary system CaClz-NaC1-CaCO3 has a range of melt compositions, where the electrolysis can be held below 650°C. In order to prevent the side reaction of carbon deposition on the cathode we have separated the anolyte from the catholyte with alumina diaphragm. The factors, which affect the level of impurities and the current efficiency of the process, are discussed.

Jan 1, 1999

By M. Friák, L. G. Wang, M. Šob, V. Vitek

"The paper gives an account of applications of quantum-mechanical (first-principles) electronic structure calculations to the problem of theoretical tensile strength in metals and intermetallics. First, we briefly describe the way of simulating the tensile test and the electronic structure calculational method. Our approach is then illustrated on calculations of theoretical tensile strength in W, NiAl and transition metal disilicides MoSi2 and WSi2 with C11b structure. In Wand NiAl, we consider uniaxial tension along [001] and [111] directions. Although tungsten is elastically nearly isotropic (C44 = C”), theoretical tensile strength exhibits a marked anisotropy (oth/001 = 29 GPa, o'th/111 = 40 GPa). Calculated results compare favorably with experimental value of 24.7±3.6 GPa obtained for tungsten whiskers grown along the [110] direction. Similarly, in NiAl, the 'hard' orientation [001] differs very significantly from the [ill] orientation (oth/001 = 46 GPa, oth/111 = 25 GPa). This anisotropy is explained in terms of higher-symmetry structures present or absent on the calculated deformation paths. In disilicides, the theoretical strength is calculated for [001] loading (oth/001 = 37 GPa and 38 GPa for MoSi2 and WSi2 , respectively). The role of relaxation of internal structure parameter is discussed and changes in bonding conditions during the tensile test are analyzed.IntroductionIn most engineering applications, the strength of materials is limited by the presence of internal defects. If there were no defects, then, for example, the tensile strength could be several orders of magnitude higher and its value would be comparable with that of shear modulus. Therefore, the strength of ideal (defect-free) crystal represents an upper limit of attainable stresses, which is called the ideal strength. While it may not be possible to achieve the ideal strength in practice, it is not possible to exceed it. However, the ideal strength is already approached in situations which are technologically relevant. These include the low-temperature deformation of inherently strong materials, such as diamond, Si, Ge and some of the transition-metal carbonitrides, deformation of whiskers, nanoindentation of materials with low defect densities, hardened thin films and coatings etc. The ideal strength sets the limits of elastic stability of a solid. Its knowledge is useful for estimation of the ideal work of fracture stresses needed for homogeneous nucleation of dislocations and for modelling of crack propagation."

Jan 1, 2001

By Robert A. Reiley

Under the traditional environmental paradigm, industry, stakeholders, and government impact the environment through production, consumption, and regulation. For more than twenty years, this paradigm has survived more or less unchallenged. Environmental action has followed a typical pattern: industry pollutes, the public clamors, government enacts legislation, and industry expenditures for pollution-control equipment soar. In the 1990's, many groups realize that command-and-control techniques may not be the most effective method of dealing with environmental issues in the new millennium. The need for regulatory reform became apparent in the 1980's after an accident at the Union Carbide plant in Bhopal, India. In addition, the prospects of an integrated European market and increased global trade sparked a need for common standards regarding the production of goods and services, which led to the adoption of the International Standards Organization (ISO) 9000 Quality Standards. These factors, and others, triggered the development of the Environmental Management System (EMS). Over the past decade, country-and industry- specific EMSs were developed. However, the IS0 realized the need for a single, internationally recognized standard that would be workable for any type organization. The goal of this standard is to promote economic competitiveness, remove trade barriers, and promote environmental protection. To this end, the IS0 14000 Standards were developed to provide business with a structure for managing environmental impacts. This article argues that a new paradigm has begun to transcend the old. Protection of the environment if shifting from "government drivers" to "market drivers". This shift means that industry and stakeholders, instead of government, are taking the lead to develop ways to protect the environment. This article also argues that government can use this new paradigm, in a time of declining budgets and regulatory reform, to continue to protect the environment through increased compliance monitoring and rigorous enforcement. Specifically, the IS0 14000 Standards can allow the government to reduce compliance costs, streamline permit and reporting requirements, and provide business with regulatory flexibility. Finally, this article argues that IS0 14000 will be central to the regulatory reform effort, because it can be internally implemented with little need for legislative intervention.

Jan 1, 1999

By Ma Keyi, Yang Xianwan, Zhu Xiaoyun, Guo Zhongcheng, Zheng Yanping

"The oxidation of the Multifunctional Electrodeposited RE-Ni-WP- SiC Composites at high temperature is investigated. The results show that during high temperature oxidation the relationship between the mass change of pure Ni , Ni-W-P, Ni-W-P-SiC or RE-Ni-W-P-SiC coating and the oxidation time follows a mixed curve, i.e. it is approximately a linear relationship when the oxidation time is less than 60 mins while it is a power function relationship when the oxidation time is over 60 mins. The order for the oxidation rate of the four coatings is Ni> Ni-W-P> Ni-WP- SiC>RE-Ni-W-P-SiC. The mass change of Ni-W-P, Ni-W-PSiC or RE-Ni-W-P-SiC coating increases exponentially with a rise of oxidation temperature. The high temperature-oxidation resistance of RE-Ni-W-P-SiC composite coating is 3-4 times that ofNi-W-P alloy coating. The cross section morphologies and Xray diffraction patterns indicate that the high temperature oxidation resistance of RE-Ni-W-P-SiC composite coating is better than any other coatings.1. IntroductionWith the rapid development of modem industries the products in engineering industry are continually challenged by the requirements of long-term and stable working at higher temperature, pressure, speed and under adverse conditions. Consequently, the surface properties of the products, such as the resistance to oxidation at high temperature, the resistance to wear and the resistance to corrosion, should be improved continually."

Jan 1, 2000

By Philip Arthur

The ISASMELT process is making a significant contribution to the global metals industry. ISASMELT furnaces are now operating successfully in eight different countries and treating approximately 3 million tonnes of concentrates and secondary materials per year. The process is currently used in both lead and copper smelting. The most recently commissioned plants were in Germany and China, one for treating scrap copper and the other treating low-grade copper concentrates. The Copper ISASMEL T furnace ("CIF") at Mount Isa Mines Limited (UMIM") has continued to set new operational records, with throughput of more than I million tonnes of concentrate per year and very low operating costs. This paper summarises the latest operational data from the Mount Isa Copper ISASMEL T plant and outlines the successful approach to industrial R&D taken by MIM in the development of the ISASMEL T process.

Jan 1, 2003

By C. Cánepa

In the treatment of many problems related with the optimization of a given ore dressing process, microscopic studies can provide invaluable assistance. Such studies are generally carried out through mineralogical determinations both qualitatively and quantitatively. Frequently the solution of a specific problem requires the combination of these in adequate proportions. Often the nature? of the problem poses some conditions regarding the way the microscopic determinations are made in order to yield useful information. Most publications applied to mineral beneficiation show results of ore microscopy without mentioning the methodological details involved in the determinative work and therefore it is not possible to judge their reliability and/or their relevance. As methodology must necessarily change from case to case, it is very important for the microscopist to identify first the direct and indirect mineralogical information required to solve the problem. Without such guidelines selection of methods for the qualitative and/or quantitative determinations cannot be made.

Jan 1, 1981

By C. P. Broadbent

The process metallurgy of many nickel laterite smelting operations is controlled largely by the physical chemistry of the slag system. Consequently, accurate phase diagram information and physicochemical property data are essential to interpret and predict the behaviour and optimisation of the overall process. The system (SiO2 - MgO - FeO) first described by Bowen et al. between 1914 and 1935 and the system (SiO2 - MgO - FeO - Fe2O3) determined by Muan and Osborne in 1956 are of particular relevance to the study of nickel laterite smelting slags as these systems form a reasonable approximation of many industrial slags. This paper will review the literature for these (and other relevant) phase systems. In addition data available from the ternary and (quasi)ternary phase diagrams will be compared with data obtained from industrial slags. The physico-chemical properties under consideration will include; melting and crystallisation behaviour (solidus and liquidus temperatures), viscosity - temperature relationships, heat flux considerations, electrical conductivity, surface and interfacial tension.

Jan 1, 1993

By Malcolm J. Harrison

The problems associated with the flow control of abrasive slurries and solids laden fluids creates reliability problems in many mining operations. Conventional valves such as pinch, knife gate and plug types cannot always function reliably in such harsh operating environments. Due to the technological advances in the hard coating industry, ball valves can now be produced with internal surfaces protected from the erosive effects of these applications. Pressures well in excess of the capability of conventional 1000 kPa working pressure valves can now be handled reliably. The significant advantages of minimizing down-time and lowering maintenance costs can now be realized with metal seated ball valves.

Jan 1, 1999

By George Kachaniwsky

Until mid-1982 the Mines Gaspe copper smelter consisted of a fluid bed roaster, a reverberatory furnace, two Peirce-Smith converters of which only one was blowing at any one time, anode casting facilities, and a single contact sulphuric acid plant treating both roaster and converter gases. Reduced concentrate supplies have led to the shutdown of the roaster and, as a result, it was necessary to adapt the converter and acid plant operation to the new operating mode: green concentrate smelting with resulting lower matte grades and acid plant treatment of off-gases from only one blowing converter. Therefore, modifications were carried out to existing equipment and methods of operation and control. This paper describes the result of work done to obtain steady, maximum strength, converter off-gas flow and an efficient acid plant operation. Topics covered include: optimization of converter operation, tightness of hood and off-gas ducting, improvements in acid plant/converter communications and modifications of acid plant operation and control to cope with the fluctuations in converter gas flowrates and strengths.

Jan 1, 1983

By Milton Blander

"A review of concepts and theories for predicting thermodynamic solution properties of multicomponent high temperature liquid solutions is reviewed. During the last 50 years the ability to predict such properties for molten salts, silicates and metals based on the generally known properties of the lower order (often binary) systems has been developed and shown to provide predictions which are quite useful in science and technology. There are many gaps in our understanding of these high temperature solutions, especially for metals, and considerably more work is needed.INTRODUCTIONA number of solution theories and concepts have been developed which reliably predict the properties of multicomponent solutions from those of the lower order systems (often only the binaries). Because there is available data for a large fraction of the important binaries, the capability for making predictions for many multicomponent systems used in metallurgical separation processes is broad and potentially very useful. At the very least, the theories greatly minimize the data necessary for predicting properties of complex multicomponent solutions of molten salts, silicates and metals. It is the purpose of this paper to discuss the concepts which are demonstrably useful. We will discuss simple forms of the theories to make the concepts clear but we will refer to the publications which contain the more complex equations needed to treat the large majority of systems.A simple framework for understanding what we need to know in order to make technologically useful predictions is based on well known thermodynamic principles. In technologies and sciences where molten salts, slags magmas or molten metals are used or studied, one must often calculate the extent of a chemical reaction (or separation) or of phase changes. To do this, one must first write an equilibrium constant, K, for the reaction in terms of the standard free energy change of the reaction, ?G°."

Jan 1, 1996

By Omid Marzoughi

In this research, both the kinetics and the mechanisms of the roasting of a sphalerite concentrate from the Bafgh mining complex in Iran were investigated. The oxidation process was performed in a muffle furnace in air and the effects of time and temperature on the degree of oxidation of the zinc sulfide sample were quantitatively studied. The experimental data were fitted to the shrinking core model. In the temperature range of 650–800 °C, the rate-controlling step was the chemical reaction between the zinc sulfide and oxygen with an activation energy of 103 kJ mol−1. On the other hand, in the temperature range of 850–950 °C, the rate-controlling step was oxygen diffusion with an activation energy of 50 kJ mol−1. Also, the roasting process was studied using thermogravimetric (TGA) and derivative thermogravimetric (DTGA) techniques.