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By Bien Ferrer

In most smelting operations, there is a strong incentive to improve safety, reduce downtime and extend the campaigns of furnaces and related equipment. An asset management strategy that is based on information, rather than simple throughput metrics and intuition, can be developed to improve uptime and unlock value currently unrealized at existing smelters. Advances in digital technology, including data analysis, modelling and monitoring for hot pyro-metallurgical vessels, make it possible to assess the current condition of an asset, as well as to make more informed projections about its future condition, using on-line and historical data. This would allow practices around asset management to be more proactive and less reactive, with the end-result of optimized uptime. ‘Digital Asset Management’ describes a concept in which digital technology is used to support an asset management strategy and accelerate decision-making by providing information on what, why and how an asset should be designed, operated or maintained. With the overall goals of effective resource utilization, optimized operations, capital efficiency and social acceptance, Smelter 4.0 is a program of holistic improvement and is underpinned by the effective use of data to drive decisions. This paper focuses on Asset Reliability, which is one of the improvement pillars of Smelter 4.0, and introduces a methodology that is aimed at closing the gap between recorded data and evidence-based decision-making through Digital Asset Management.

By J. R. Goode

There are at least a dozen methods of selectively removing cerium from a mixture of the rare earth elements (REE) including separation techniques based on the oxidation of cerium to the quadrivalent state. Several of the oxidation processes have been operated on a commercial scale, others have been tested and in some cases are part of proposed flowsheets. In this paper, we describe and compare the various methods. We also present preliminary estimates of the costs of early Ce removal and discuss recovery and purity aspects of the options.

By Wei Yu, Tiejun Chun, Jian Pan, Deqing Zhu

In this paper, the technology of producing fluxed pellets by using hydrated lime as binder instead of bentonite was carried out. Green balls with 0.8% bentonite and others with 2% hydrated lime were obtained under the same conditions of 1.5% coke, 1.45 basicity and balling at 8.5% moisture for 13 min in disc pelletizer. The properties of two types green balls were as follows: drop numbers of 4.8 to 5.0 times/0.5m, compressive strength of 19.7 to 24.2 N/pellet and thermal shock temperature of 280 to 385?, respectively. Comparing with bentonite as binder, the compressive strength of fired pellets with hydrated lime is elevated by 13.8% and climbs up to 3113 N/pellet under the following conditions: preheating at 1050? for 10 min and firing at 1300? for 15 min. The hydrated lime also improves the metallurgical performance of fired pellets. The reduction index was enhanced from 68.6% to 70.6%, RDI+3.15 increased from 90.1% to 98.8% and reduction swelling index dropped from 22.4% to 7.4%, respectively. Therefore, hydrated lime can not only replace bentonite as binder to enhance the firing behaviors of green balls, but also effectively improve the metallurgical performance of fluxed pellets which can be used as high quality feed for blast furnace.

Jan 1, 2011

By Pertti Koukkari

The novel Jarogain process combines treatment of the jarosite residue of zinc manufacturing and processing of arc furnace dust from steelmaking to a holistic recovery technology. The new hydrometallurgical approach is targeted to recover the major constituents (Fe, Zn, Pb) as well as valuable components such as Ag, Au, In and Ga from the jarosite-dust mixture as reusable concentrates. The fractionation process proposed by VTT and Aalto University takes advantage of jarosite being readily fine powder and directly available for wet chemical processing. Jarogain process provides an energy efficient opportunity for jarosite utilization as value added products. The experimental proof-of-concept of key stages of the process will be outlined with a comparison of available pyrometallurgical treatments of jarosite waste. The techno-economical assessment is based on estimated investment and variable production cost using the discounted cash flow (DCF) analysis.

By G. Nazari

ERAMET, through its subsidiary COMILOG, have rights to a rich niobium and rare earth deposit inGabon. The Mabounié deposit, is located 50 kmfromthe town of Lambaréné, in a fairly remote location. ERAMET has been developing a process to recover value metals for several years, and approached Hatch Ltd. to design a sizeable Demonstration Plant to help them further optimize the process, and prove the flowsheet is technically viable. The process employs concentration techniques to recover an upgraded Nb/REE feed material for processing in the subsequent leach step. Rare earths and niobium are selectively leached, and subsequently precipitated. Following precipitation, rare earths undergo bulk separation and are purified to produce LRE and mixed MRE/HRE products, which will be further processed by Third Parties. This paper provides a high-level overview of the process, summarizes the motivation for a Demonstration Plant in the vicinity of the deposit, and discusses technical challenges faced during the flowsheet definition and design phase. Key challenges are focused on and summaries of the methodologies used to address each challenge, as well as the solutions to overcome the challenges, are discussed. The paper provides motivation for further process simplification and concludes with a project update.

By Evgueni Jak

Recent advances in analytical, experimental techniques, and computer-based theoretical modelling of fundamental properties and elemental processes, provide new opportunities to develop the next level of whole-of-reactor pyrometallurgical furnace models. These models have the potential to significantly improve the prediction of, and adding value to, industrial operations. In non-ferrous smelting, the starting point of these models is the development of multicomponent thermodynamic databases for gas-slag-matte-speiss-metal-solids phases supported by systematic experimental research. The whole-of-reactor-models additionally should take into account kinetic processes taking place at micro- and macro- scales, and other key factors. Examples of applications of the latest research tools and modelling approaches to analysis of industrial flash and top submerged lance (TSL) sulphide smelting processes are presented. Different levels of industrial modelling are discussed from elemental local reactions, through general and more detailed whole-of-reactor-models, to plant sections and further to whole plant operation models. Some principles for development of pyrometallurgical reactor models are discussed.

By Naiyang Ma

"High oil concentration is one of the major barriers for recycling of mill scale of steel hot rolling mills. It is of vital importance to find cost-effective technologies of reducing oil concentration in mill scale in order to recycle the mill scale without causing detrimental effects on production and environment. This paper discusses in-process separation of mill scale from oil at steel hot rolling mills. Formation of mill scale and status of oily wastewater at hot rolling mills are reviewed in the first place. A mathematical model is then formulated to relate oil concentration in mill scale to physical properties of mill scale, chemical and physical properties of wastewater and interacting parameters between mill scale particles and wastewater. From this model, three approaches of in-process separation of mill scale from oil are derived: (1) avoiding contacts between mill scale particles and oily wastewater, and (2) maintaining low oil concentration in wastewater, and (3) collecting mill scale in upper streams of wastewater flows. In-process separation of mill scale from oil might have advantages of lower capital cost, lower operating cost and less additional environmental concerns, compared to other strategies of separating mill scale from oil.IntroductionHot rolling is an inevitable step in producing finished steel products. Figure 1 schematically shows a steel hot rolling process. Semi-finished steel products, slabs here, are reheated first, and then the reheated slabs are discharged from the furnaces and transported on hot rolling trains to descaling units for removing scale with pressurized water. After being descaled, the slabs are rolled by roughing mills. After treated with cropping and the second descaling, the slabs are finally rolled into finished products, coils here, by finishing mills."

Jan 1, 2012

By C. Peter Hayes

The world continues to change and with it the supply of minerals and metals, the location of centres of production of primary metal and the increasing levels of metals and materials recycling. New technologies are being developed to meet the ongoing search by industry for lower costs, cleaner production and new markets. To keep abreast with these changes, and to utilise fully, the potential benefits of these technical advances, the industry will need a professional workforce having different knowledge, skills and professional attributes than in the previous millennium. What are these skills and attributes? How to best attract and develop the metallurgists of the future, and provide for the ongoing educational and research needs of the industry?

By Na Wang, Chao Du, Yao Zhang Shuqiang Jiao, Hongmin Zhu

"Na2NbAlO5 was synthesized using Nb2O5 and NaAlO2 as raw materials in molten NaCl-CaCl2 by a solid reaction. With an addition of sodium into the melts, Na2NbAlO5 was subsequently reduced to form NbAl3 intermetallic compound with a particle size of 50-300nm.IntroductionThe intermetallic compounds of niobium aluminides have been a subject of research interests as high temperature materials because of their properties such as high melting temperature, large specific strength at elevated temperature, good resistance to high temperature oxidation, low density and large ductility [1,2]. They are applicable for turbine blades in aircraft engines and stationary gas turbines [3,4].In recent years, the methods of powder synthesis have been widely discussed. There are many methods to synthesis intermetallic compounds such as conventional melting and solidification [5], powder metallurgy [6,7], reaction sintering [8] and reaction sintering with prior mechanical activation [9,10]. There is a prominent weakness in such methods that they use metal to produce intermetallic compounds by the means of diffusion reaction. Although the metal can diffusion sufficiently, it is still hard to avoid maldistribution of the constituents which impairs the properties of the materials."

Jan 1, 2012

By Shivendra Sinha

Total pressure oxidation (TPOX) is widely outreached leaching practice for base metals from sulfide minerals, wherein high temperature (T ∼ 200 °C) and oxygen pressure (pO2 ∼ 25 bar) are required. These aggressive conditions intensify the oxygen mass transfer, and therefore facilitate metal dissolution. However, challenging-cum-negative aspects of such practice are energy and material intensive requirements and high oxygen demand. Thus, the present study explores the novel emulsified medium for enhancement of oxygen mass transfer, which assists faster metal dissolution at significantly lower temperature and pressure condition. It is possible to achieve quantitative dissolution (>95%) of Cu, Ni and Co from mixed sulfide minerals at T ∼ 95 °C and pO2 ∼ 2 bar using an emulsion of 2.5% (v/v) n-Hexadecane in dilute sulfuric acid. In addition, n-Hexadecane was found to be inert, stable and immiscible in a pressurized leaching system, thus can be easily separated and recycled in subsequent leaching stages. Thus, this study offers an energy efficient route for low temperature-pressure leaching of sulfides.

By V. R. Voller

"The World Wide Web (the web) provides a very useful resource for the enhancement of teaching and research dissemination. This paper advocates that researchers take control of this resource and become actively involved in creating web content. Two examples of the use of the web in a materials setting is provided. The first illustrates how a concept quiz for teaching can be developed. The second shows how a materials processing model can be run in real time over the web. The paper closes with a summary of some resources that can be used to create web materials.IntroductionA recent copy of a newspaper advertisement read""Share what you know, learn what you don't""This neat phrase sums up a powerful teaching and research philosophy. In an educational setting a prime motivation for research is to uncover the unknown and venture in directions previously uncharted. The balance to this search for knowledge should be a desire to share that knowledge with others; whether it be with students in the classroom or research colleagues in a wider setting.The .World Wide Web and its associated multi-media software offer a perfect platform for researchers to share their knowledge with an extremely wide sector of the research community. To enable the use of this resource researchers must take the power that the web offers them into their own hands and create products that take maximum advantage of the medium. It is key that researches at the forefront become directly involved, otherwise a potential powerful medium will not realize it's true potential, and colorful products with no core content will proliferate. The object of this paper is to outline two ways in which the web can be used to enhance teaching and research objectives."

Jan 1, 2000

By Peter Koh

The velocity solid charge attains when dropping down concentrate chutes is an important boundary condition when developing mathematical models of flash furnace burners and reaction shafts. In this work an experimental rig was developed to measure the velocity attained when nickel concentrate and sand were dropped down a vertical pipe 3m long. The velocity measurements showed that the nickel concentrate did not fall as individual particles. The measured values of the velocity approached, but did not attain, those calculated for solid bodies, the disparity being attributed to friction at the pipe wall and fluid drag losses. After falling 2 m velocities between 5-6 m/s were attained. The analysis was extended and applied to understanding the intermittent problem of puffing which sometimes occurs from the top of the concentrate chute. The pressure at the bottom of the chute is the net result of two opposing pressures, namely that developed by (a)the process air entering through the velocity control device, and (b) the solids falling down the concentrate chute. Flow back up the chute occurs when the former exceeds the latter. The process air pressures in the burner were obtained from CFD simulations of a full burner. Variables considered included air speed through the velocity control device, drop height and furnace draft. The analysis was useful in highlighting the operating conditions which were conducive to puffing and in establishing procedures to minimise its occurrence.

Jan 1, 2006

By Feng Gao

A general unsteady- state model, based on a cracked substrate, has been developed to account for reaction and diffusion within porous substrate during oxidation of Carbon Fiber Reinforced Carbon matrix (CIC) composites. The effects of several parameters, such as diffusion and reaction rate ratio, oxygen concentration, and composite density, on oxidation process are explored. Also, theoretical results for a set of parameter values of the CIC composites are compared with experimental data. It shows that the model predicted values agreed well with the experimental data in weight loss. Based on this model, quantitative predictions of oxidation of a composite with cracked substrate can be made.

Jan 1, 1993

By Karin Soldenhoff

Recovery of uranium in conventional ion exchange circuits, using strong base or weak base resins containing quaternary or tertiary amine functional groups, is based on an anion exchange mechanism. In saline liquors, chloride competes with uranium for the active resin sites and reduces resin loading. This results in significant negative impacts on the IX process in terms of plant throughput and operating costs. In this paper we present the results of a study on the recovery of uranium from an acidic in situ leach liquor containing approximately 9 g/L chloride. A range of resins was tested, and a high capacity strong base resin was identified with significantly enhanced loading compared to conventional resins. Other process-relevant criteria such as loading kinetics and elution efficacy are also discussed. The process developed was successfully tested during a recent ion exchange pilot plant operated in conjunction with a field-leach trial.

By Krishna Parameswaran

This paper illustrates sustainability considerations in copper hydrometallurgy using examples of practices at ASARCO LLC, an integrated U.S. primary copper producer. Using the classic Brundtland Commission development of sustainable development, i.e., “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” the paper discusses how copper hydrometallurgical processes can be sustainable. The examples used to illustrate sustainable development and related concepts include: water conservation opportunities in milling and leaching operations; implementing green chemistry and promoting product stewardship in the electrorefining of copper.

By R. Schuhmann

The thermodynamic data and calculations which underlie the design of the Q-S process for coppermaking are summarized. The efficient production of crude copper and slag of low copper content in a single con¬tinuous converter requires the establishment and control of gradients in oxygen activity and other physico-chemical variables throughout the reactor. These gradients are established by stagewise introduction of oxygen and solid feed materials to provide: (a) flash oxidation of sulfides above the bath, utilizing the great bulk of the oxygen, (b) conversion of high grade matte or white metal to crude copper by bottom blowing with restricted bath turbulence, (c) close approach to equilibrium staging of converting and deconverting reactions along the length of the slag layer, from a maximum oxygen activity near the metal discharge end to a minimum at the slag discharge end, and (d) completion of slag cleansing by deconverting. In terms of the Phase Rule, the Q-S process involves a system with a minimum of 5 components (Cu, Fe, S, O, and SiO2) and several liquid, solid, and gaseous phases. Accordingly, basic data from previously reported studies on simpler systems are utilized to prepare an equilibrium diagram for the 5-component system and to generate a quantitative thermodynamic model for the Q-S process. This model shows in particular the ranges of oxygen activities (measured by equivalent CO2/CO ratios) involved in the Q-S process and the relations of oxygen activity to temperature and other important physico-chemical variables of coppermaking.

Jan 1, 1976

By Susumu Nagae, Hajime Ikeda

Recently, a number of mine development projects have been setback by social, economic and, environmental circumstances that had not been seen before. Many of these problems do not always originate from direct mine pollution. Typical examples of these are· conflicts between the exploration company and the local residents, sudden objections just before the development is to begin, and unexpected tightening of environmental regulations. The common background to these problems is expanding global environmental awareness. This includes complex factors ·such as the expansion of exploration to remote regions, the brisk activities of environmental NGOs, the increase of international environmental laws and, governmental policy changes. Today, the range of issues concerning mine development is widening significantly. The participation of local residents arid NGOs in the development planning, together with the company and government, has become essential for smoothly carrying out mine projects and making them more beneficial for stakeholders. Introduction The common image of the environmental problem with respect to mining is direct mine pollution, such as the collapse of tailings dams, pollution from refineries, and acid mine drainage. All over the world, the mining industry has made large investments in capital and technology to solve and prevent mine pollution, and these efforts have been making steady achievements. However in recent years, new cypes of environmental problems which are not originating directly from mine pollution are emerging frequently. Most of the problems are concentrated at the exploration stage to early stage of development, which have less impact on the environment. In the worst case, mining project may be forced to cancel and could cause serious damage to the industry because they could not collect their investment. I would like to take a general view of the examples of new types of trouble, their characters, background, and strategies against these problems.

Jan 1, 2000

By E. R. Vance, D. R. M. Brew

"Historically, Ordinary Portland cement has been the preferred medium to immobilise arsenic. However, arsenic in cement gives rise to calcium-arsenic phases and their known decomposition to calcium carbonate and arsenic trioxide via atmospheric carbonation raises serious questions about the long-term suitability of cement for arsenic immobilisation. Alternative matrices such as low-temperature ceramics (LTCs) potentially offer superior resistance towards carbonation owing to the absence of calcium. Consequently, the potential for arsenic immobilisation using LTCs has been investigated. Both AsIII and AsV have been incorporated and samples assessed according to a standard leaching protocol. AsIII persists in the porewater of alkali-bonded LTCs as sodium arsenite rendering them unsuitable for immobilisation. Thermal treatment of these LTCs to consolidate the microstructure and reduce open porosity resulted in sodium-rich cryptocrystalline matrices that leached arsenic and sodium readily. The omission of sodium in acid-bonded LTC formulations resulted in leach data that were close to the target value of 5 µg/ml in Toxicity Characterisation Leaching Protocol tests.IntroductionArsenic is a carcinogenic substance and its adverse effects of on humans, flora and fauna have been well documented [1-5]. As a consequence, many papers have been written on the prospective handling of arsenic-bearing waste. These can largely be divided into: (a) cleanup of arsenic-contaminated water using bacteria, precipitation, and/or UV irradiation to generate arsenic-rich sludges for subsequent immobilisation; (b) cleanup of arsenic-contaminated soil via chemical extraction for immobilisation of the As concentrate; and (c) immobilisation of industrial waste contaminated with As."

Jan 1, 2008

By M. H. Lin, S. Kou

"Czochralski pulling has been a very widely used process for growing single crystals for electronic and optical applications. Dopant segregation can significantly degrade the quality and yield of single crystals. We have used the floating-crucible technique for segregation control in Czochralski pulling, our floating crucibles being unique in that the melt passageway is very long. As such, dopant back diffusion is suppressed, even when the cross-section of the melt passageway has to be relatively large to help the melt go through or when the pulling rate is very low. Single crystals of model materials K-doped NaN03 and Pb-doped Sn have been grown with very uniform dopant concentrations. IntroductionSingle crystals of electronic and optical materials are often doped with a small amount of impurities to develop required physical properties, e.g., P and B in Si for n-type and p-type semiconductors, respectively, and Nd in YAG lasers. Dopant segregation can result in nonuniform physical properties, thus degrading the quality and yield of the resultant crystals.Figure 1 is an illustration of the conventional Czochralski process for crystal growth. Several techniques have been developed to control dopant segregation in Czochralski pulling, including the push-pull technique (1,2), the drop-pull technique (3-7) and the floating-crucible technique (8-13). The first two techniques require precise sensing devices and feedback control systems to keep the feeding rate equal to the pulling rate. The last technique is simple since the feeding rate is automatically equal to the pulling rate."

Jan 1, 1994

By Alexandra Anderson

A computational fluid dynamic (CFD) model has been developed using ANSYS Fluent 17.0 to help identify areas of high wear within the refractory lining of a secondary lead reverberatory furnace. Once a base case simulation was validated using data from an operational furnace, areas of potentially high refractory wear were determined through the calculation of the temperature and velocity distributions within the furnace and on the hot face of the refractory lining. The CFD model was used to assess whether the predicted areas of high refractory wear could be minimized through changes burden geometry. The results showed that shape of the burden geometry greatly affected the overall flow patterns and heat transfer within the furnace.