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By Patricio F. Mendez

This paper presents a formalism to automate portions of the traditional scaling procedure. This formalism, called here Order of Magnitude Scaling (OMS), captures essential components of the governing equations into a set of matrices and arrays amenable to computer implementation using standard linear algebra tools. This approach is valid and specially useful for large systems of multicoupled equations. The matrix approach proposed enables one to automate operations such as normalization, dominant balance, obtention of characteristic values, and check for self-consistency. Also, automation permits an exhaustive exploration of all possible balances and the discovery of unsuspected scaling laws. As an example, OMS is applied to the analysis of the viscous boundary layer with no external pressure gradient. The obtained scaling laws for boundary layer thickness and transverse velocity are the same as those obtained with traditional scaling, and in addition, a meaningful estimation for pressure variations within the boundary layer is obtained; this last estimation is typically not addressed in the manual analysis.

Jan 1, 2006

By Theo Lehner

"During my first contact with industrial metallurgy as a summer vacation worker at the Steelplant at Luleå, Sweden, I came during a visit to MEFOS into contact with works of Prof. Worner caried out during the piloting of the Worcra continuous steelmaking process. These tests are still today remarkable as an innovative step in the art of metalmaking. By that they involved the necessary ingredients for the development of our art: seeing, knowing and doing. Industrial injection as applied during slag fuming will be discussed below.Phenomena of injection metallurgyPhenomenon according to Collins dictionary is"" anything that can be perceived as an occurrence or facts by the senses"". To open the senses for the interesting phenomena in pyrometallurgy must be the main task of any educator. The investigations by Engh et al. around the mixing phenomena of the WORCRA process are an early example of combining senses with knowledge. To see what you model must be a crucial part in any development. This can also involve to see and control that one is subject to the same conditions as in published models. Below the need ""to see"" will be illustrated by some recent investigations around slag fuming. In the literature various models for reactions occuring during the fuming of slags are presented. Two recent models hint ·ata) the occurrence and importance of iron for the fuming processb) the occurrence and importance of lead droplets during respectively."

Jan 1, 1996

By Murray Hughes, Neil Brown, John Carran

"A control system architecture has been developed using the Ward-Mellor structured analysis techniques for real-time applications. This approach has produced several advantages over traditional control system implementation methods including:•,partitioning of the control system into discrete control functions.•,easy identification of the interaction between individual control functions and the rest of the system including the impact of changes at the control system boundary (i.e. additional inputs or outputs).•,simplified control software testing.•,a closed loop design, implementation and documentation process.This paper describes a generic control application in which the process specification and control system design are logically linked. Both components are used by process engineers for on-going development.IntroductionAluminium is reduced from alumina in multiple electrochemical semi-batch reactors. Raw material additions and molten metal withdrawal are made at discrete intervals ranging from seconds to days. The electrolytic reduction process is continuous, despite the semi-batch nature of the material inputs and outputs. The chemical and physical processes that occur within each reactor are complex and interdependent, therefore simple methods used for the control of many chemical processes are impractical. The process control system is required to optimise operating efficiencies within the safe operating zone.The process control of aluminium reduction cells is heavily biased towards calculation of process variables with relatively few measured sensors. Each cell is controlled independently of the other cells, although changes to process conditions and raw material . quality will affect all cells. The process responds relatively slowly and with significant time lags. Measurements and process variable calculations occur each second, however the accuracy and precision of actuator response and sensor sampling are measured 111 milliseconds. Time-based scheduling is a significant component of reduction cell control."

Jan 1, 1994

By Jr. Brown, A. Calderara, A. L. Antozzi

"The result of extensive research into fundamental mixed metal oxide catalyst morphology has produced a next generation all titanium Dimensionally Stable Anode (DSA ®). This new DSA ® anode, patent pending, is tailored for electrowinning of non-ferrous metals (copper, nickel, cobalt, zinc) by means of this new coating technology.These DSA ® anodes are characterized by a hanger bar with vertical distributor bars, having primary titanium mesh attached by weldments. The active mesh is provided with noble-metal electrocatalytic coatings, consisting of iridium and/or ruthenium oxides, obtained by thermal decomposition of precursor solutions applied to the titanium substrates. The catalytic activity of state-of-the-art DSA ® anodes is increased by controlling the crystallite size of the noble-metals without decreasing the decomposition temperature. It is known that below a certain value (typically 400°C) the stability of these oxides, and associated lifetime, is seriously compromised. A highly active DSA ® anode, consisting of a quasi-amorphous phase, is obtained at high temperature (above 450°C), therefore not compromising lifetime performance. Through optimization of these design parameters, the manufacture of these novel anodes was identified.DSA ® anode performance advantages include: lead-free ' green' all titanium anodes, true leadfree cathode quality, energy savings of 0.3 to 0.55 V can be realized depending on the EW application when compared to industry standard lead-alloy anodes, eliminate need for cobalt sulphate addition required for lead anodes, sustainability designed into long-life recoatable anode structures, increase plant cathode output through increased current density operations, improve plant on-stream production, no sludge generated or removed, and improve current distribution producing smooth high efficiency cathode.Introduction of ProductThere are many factors to consider when engineering a high performance DSA ® electrowinning anode. Half of the anode's performance is derived from the physical attributes of the electrocatalyst and methods employed when applying this catalyst to the titanium anode structure. The other half of the performance benefits relate to the proper structural design of the anode. In this paper, we will highlight the anode development program in which De Nora has invested to provide the Electrowinning marketplace with a high performance anode product."

Jan 1, 2012

By M. Boussuge, M. -D. Dupuits, A. Piant

This paper summarises a part of the work that has been essentially carried out at the Ecole des Mines de Paris in the framework of an Eureka European programme funded by the French Ministry of Industry, in partnership with Metaleurop and Carborundum (subsidiary of Saint Gobain). It deals with the measurement of different properties (density, thermal linear expansion, elastic modulus, strength) of a SiC-based refractory constituting the trays that are used in the refining columns in the New Jersey zinc distillation process, especially in the boiling section. These parameters have been investigated to check the homogeneity of the asreceived trays as well as to estimate the influence of ageing of the material under operating conditions. With this aim, specimens have been sampled in used trays having more than two years of operation. The as-received trays exhibited a good homogeneity, the strength being slightly lower in the direction in which they are compacted. Despite microstructural changes, most of the properties measured at room temperature are not significantly affected by ageing. High temperature tests involved thermal treated under vacuum to remove metallic zinc before testing at high temperature. An increase in temperature, as well as ageing, induces a decrease in the elastic modulus and strength.

Jan 1, 2000

By Funsho K. Ojebuoboh

With several "green" applications in the horizon, bismuth has become an even more important minor metal in the smelting and refining of lead. Smelters with a complex sulfide feed invariably deal with bismuth. Its behavior during the smelting of lead in conventional sinter - blast furnace operation is discussed. Because it readily deports to the lead phase during the refining of lead, its separation from refined lead remained unsatisfactory in early lead production. When commercial requirements of bismuth in lead became more stringent early this century, the procedure whereby calcium and magnesium is used to debismuthise lead was developed. The present conduct of this 1936 process, the Kroll Betterton process, is discussed with emphasis on operational improvements.

Jan 1, 1995

By G. F. Archer

Selenium and tellurium, trace metals found in copper smelting, report to blister copper during smelting. Winning these metals from anode slimes, the primary commercial source, is discussed. At Asarco's Amarillo Copper Refinery, slimes treatment segregates selenium and tellurium to a water-soluble soda slag. Aqueous precipitation of tellurium oxide and selenium by sulfur dioxide is valence dependent. Se+6 and Te+6, which constitute a portion of total selenium and tellurium, are not susceptible to this base case treatment. "Secondary Selenium" is formed from these hexavalent species. We describe a process whereby simultaneous oxidation of selenium and tellurium effects a separation. Process conditions for separating selenium dioxide, and efficiency of fume capture are examined.

Jan 1, 1995

By Bernard Bonnetot

The potentialities of hydrogen storage using borohydrides are presented and discussed especially in regard to the recoverable hydrogen amount and to the recovery conditions. A rapid analysis of storage possibilities is proposed taking in account the two main ways for hydrogen evolution: the dehydrogenation obtained using thermal decomposition of borohydrides or the hydrolysis of solid or dissolved borohydrides. The recoverable hydrogen is related to the dehydrogenation conditions and the real hydrogen useful percentage is determined for each case of use. The high temperatures required for dehydrogenation, even using catalyzed borohydrides, lead to poor outlooks for this storage technique. The hydrolysis conditions fix the yield of the recovered hydrogen and rule the storage capacity of the dissolved borohydride, the "fuel".

Jan 1, 2006

By Klaus Gamweger

"This paper introduces an innovative solution to open and close the tap hole of different furnace types in the copper industry with a slide gate system. Two plates with defined drilled holes are slid against each other, which enables effective starting and stopping of the copper flow as well as throttling. Typically, the copper is poured via a tap hole into a launder system by rotating the furnace into an appropriate position. Control of the casting rate is also performed in this manner. Or, in case of stationary furnaces the tap hole is opened by oxygen lancing and closed manually with a clay- or copper-cone. These procedures show a lot of disadvantages including splashing, oxygen pick-up, and energy losses as well as a severe danger for the working staff. All these problems can be overcome with an appropriate slide gate system.IntroductionThe control of the casting rate of a copper anode furnace usually is performed by rotating the furnace into an appropriate position. This implies that the taping starts with the tap hole at a very high position. Copper splashing and an uncontrolled oxygen pick up are - with several more disadvantages - the consequences. RHI AG has developed an innovative solution for copper applications to open and close the tap hole with a slide gate system which allows also an accurate control of the flow rate. By using this system it is possible to start the casting procedure with the tap hole at the deepest position, directly above the launder. This paper presents this new slide gate system in detail and shows the advantages in production and safety issues."

Jan 1, 2012

By LeRoy C. Prichard

The scrap based steel producers in the United States generate an estimated 650,000 tons of electric arc furnace (EAF) dust annually which is classified as hazardous waste, K061. These scrap based producers commonly referred to as mini-mills represented 39% of the steel produced in 1994. Based upon the EAF plants being installed or planned today, it is a reasonable projection to anticipate 50% of the steel produced in the United States will be by EAF's. Using a straight line projection of percent of steel produced to tonnage of EAF dust generated, this will result in 833,000 tons of dust being generated upon the completion of these new EAF producing plants, presumably by the year 2000. Because the United States is a capitalistic economy, a steel producer is in business to make a profit therefore dust management becomes a very important variable in the cost of making steel. An EAF mini-mill dust management program must consider at least three components. First the handling of the dust must be in accordance with the law; i.e., the Environmental Protection Agency rules and state and local municipalities guidelines governing K061. Second, it must be an economical solution that allows a company to manage its dust processing costs, a component of its total steel production costs while producing steel at a profit. Third, the dust management program should be one that is environmentally responsible; viz., the program should reclaim or recycle the dust constituents, as feedstock materials or saleable products. The first component, obedience of the law seems to be a relatively straight forward, common sense objective; however, as nearly every mini-mill operation will testify it has been a area of changing laws with confusing variations when it comes to K061. Even more frustrating is the fact that obedience or compliance today does not mean that the company will be considered law abiding in the future.The liabilities associated with

Jan 1, 1995

By Issa S. AI-Kharusy

Oxidation/reduction (REDOX) alloy media, as used in wastewater treatment, is founded on the exchange of electrons. Because of this electron exchange, many contaminants are converted to harmless components which require no further treatment. Other types of contaminants are removed from the waste stream by electrochemically bonding to the alloy medium. This paper discusses the REDOX reactions, the role of the alloy medium in various treatment processes, and describes specific applications of REDOX alloy media for the removal and minimization of waste. The characteristics and handling of spent treatment media is also reviewed as a further consideration in waste minimization.

Jan 1, 1996

By Rachel De Lucas

Current methods of hydrogen storage are an impediment to the transition of our energy infrastructure from a hydrocarbon to a hydrogen base. The transportation, handling, and storage costs of hydrogen gas account for a majority of its selling price. Magnesium hydride slurry is a safe, environmentally friendly alternative for hydrogen storage. If this form of storage is to be adopted on a large scale, a cost-effective method for recycling the enormous amounts of magnesium hydroxide byproduct must be identified. The solid oxide membrane (SOM) process can be used to recycle the magnesium hydroxide byproduct into magnesium metal, which can be reformed into magnesium hydride and reused for fuel storage. Conventional magnesium extraction/recycling technologies require a great deal of energy and create byproducts that are harmful to the environment and human health. The SOM process poses none of these detrimental effects and requires less energy and feed preparation. The economic viability of a facility that utilizes the solid oxide membrane process for the direct reduction of magnesium must be examined in more detail if industry is to consider it. Cost analysis data related to the commercial viability of a scale-up will be compared to two standard industrial processes: current magnesium production techniques including electrolytic and metallo-thermic processes. We have shown in our cost comparison that the SOM process is cheaper than these traditional techniques and that it is also comparable to aluminum's Hall-Héroult process in cost but with none of the environmentally harmful byproducts.

Jan 1, 2006

By J. W. Perez

In the treatment of process effluents containing metal ions, it is sometimes desired to remove all of the heave metal ions while at other time it is, desired to remove one heavy metal ion from another, selectively. Ion and precipitate flotation processes were evaluated to perform these functions using the copper-iron aqueous system as a model. Because preliminary foam fractionation experiments proved to be relatively inefficient, most of this work has focused on precipitate flotation using both hydroxide and sulfide precipitation. Test results indicate that by proper control of reagents and operating conditions, it is possible to substantially reduce the froth volume over that achieved with foam fractionation and to separate copper from iron selectively. Mechanisms for collector attachment to precipitates were studied.

Jan 1, 1992

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified

Jan 1, 2006

By John M. Boyle

The use of high vacuum mercury retort recovery as a safe and effective means of removing mercury from mercury hazardous waste solids rendering them non-hazardous and recovering mercury suitable for recycling.

Jan 1, 1995

By M. M. Sadawy

"The increased rate of exploitation of iron ores has resulted in a rapid depletion of high-grade iron ore deposits in Egypt. New iron reserves have to be discovered to secure the iron ore for steel production. This paper aims to study the characterization and magnetic separation of low grade Aswan iron ore. The results showed that Aswan iron ore is composed of oolitic hematite, goethite, quartz and kaolinite. The screen analysis indicated that Aswan iron ore had a uniform distribution of iron and silica in the different particle size fractions and there is no any particle size has high amount of iron or low content of silica. On the other hand the results of dry high intensity magnetic separation illustrated that this technique is not suitable for upgrading this ore.IntroductionIron is one of the common metals used in industry, as well as being the fundamental raw material used in iron-steel industry; products are wide spread even in daily uses. The total iron ore reserves of the world have been estimated as 3 70 billion tones; 160 billion tones is classified as economical, while 210 billion tones as potentially economical [1]. An estimated 98% of the iron ore exploited in the world is used in the manufacture of pig iron and steel, which are non-substitutable backbones of modem society. The rapid increase of world steel production over the last few years have required an equal increase in iron ore production, from 876.8 Mt in 2006 to 948.1 Mt in 2007 [2]. The increased rate of exploitation of iron ores has resulted in a rapid depletion of known high-grade iron ore deposits. This, in turn, has led to a dramatic increase of prices. In the absence of any major new discoveries of high-grade iron ore deposits, mining companies have turned to lower-grade materials to assess their beneficiation potential to expand their production base and beneficiation capacity, in order to satisfy future demand. Egypt is going to face shortage in iron production, consequently new iron reserves have to be discovered to secure the iron needed for the country [3]. Exploitation of low grade ores requires special equipments and techniques for recovery of minerals values. High gradient magnetic separators offer promise and great potential of application both technologically and economically in the processing of fine particles containing weakly or feebly paramagnetic components [4-6]. Within this existing framework, this research was initiated to assess the beneficiation potential of low-grade Aswan iron ore by high intensity magnetic separation."

Jan 1, 2013

By W. L. Dalmijn, E. A. Schokker, N. Fraunholcz, P. C. Rem

Many processes developed for the mechanical processing of Automotive Shredder Residue (ASR) suffer from high processing costs. We offer a distinct concept for low-cost mechanical processing still allowing high value-added recycling of the recovered materials. The basic idea behind this approach is to produce saleable pre-concentrates at the lowest possible costs that can be further processed in existing separation facilities. Our process includes screening, size reduction and magnetic separation. Preliminary studies showed that fibers in ASR are magnetic due to adhering rust particles allowing separation into a fiber fraction and a non-magnetic rigid fraction by high-intensity magnetic separation. The fiber fraction is most suited for thermal processing. The rigid fraction mainly consists of plastics and rubbers with up to 10 wt.-% of non-ferrous metals, some inert material and copper wires. This fraction is very well suited for mechanical processing by, e.g., sink-float separation in existing metal separation plants. The non-metal fraction can be processed further to recover the plastics and rubbers. The process proposed in this study is expected to be substantially cheaper than full thermal processing. In addition, as it mainly relies on existing separation facilities, it can be applied in the short term.

Jan 1, 2000

By Matthias Frommer, Carl-Peter Reipl, Reinhard Flende

"Today there is a growing demand for strip of superior steels with specifically tailored technological properties. Especially strips of high-strength, micro-alloyed steel grades applied to manufacture longitudinally and spiral-welded pipes are a growth market. Tubes are generally required to have high strength and sufficient toughness values and thus favour specific hot strip microstructures. The correlation of chemical analysis, process parameters and mechanical properties with microstructural features is still a challenging task. During the last decades, scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) have become useful tools for the characterization of complex microstructures. The EBSD data provides an immense variety of post-processing possibilities, e.g. related to grains, grain boundaries, misorientations or texture. This paper highlights the results of an advanced analysis of microstructures representing industrial produced hot-rolled strips and presents an approach to define and quantify some essential microstructural parameters.IntroductionHigh-strength microalloyed steels have been used for the production of welded pipes for more than 30 years. However, the alloy design of pipeline grades is being continuously modified and the process technology optimized because of the increasing high strength-toughness combination requirement for pipeline steels. Compact strip production (CSP®) technology is an upcoming promising route for the production of high-quality pipeline steel grades [1]."

Jan 1, 2012

By Songlin Zhang

"The McCoy/Cove mine, located in Eureka-Battle Mountain trend of Nevada, is a gold and silver deposit. Case studies of recoverable reserve estimation for gold and silver were made using multiple indicator kriging and volume variance correction. The grade tonnage distributions of recoverable reserves were constructed and compared with the distributions defined by blast hole assays. Optimal pits were generated by Whittle 4D pit optimization package to analyze the impact of different processing recoveries at different economic cutoffs. The results were compared with ordinary kriging. The study indicates that the proposed method for multi-mineral recoverable reserve estimation is more accurate than kriging in tenns of grade and tonnage. The method of using recoverable reserves for pit optimization will maximize global reserve recovery and revenue, and is more efficient than condition simulation regarding computing power.ABSTRACT ONLY"

Jan 1, 1997

By Andrew Campbell, Michael Reed

"WorleyParsons has used Discrete Event Simulation methods in conjunction with more traditional process models to assess the performance of copper smelting operations. This work was performed to determine the plant capacities and suitability of proposed debottlenecking options including accounting for the planned and unplanned (breakdowns) shutdowns in the various parts of the plant and supply chain. This paper outlines the methods used along with demonstrating the benefits of selecting a feasible option and minimizing capital and operating costs.IntroductionTraditionally for de bottlenecking studies of smelters and other process plants, a mass balance is performed based on continuous operating rates and expected operating hours. Smelters have several points of failure that will restrict, if not take the entire plant offline. By using a more detailed model, validated against plant experience, bottlenecks can be demonstrated and strategies to remove them to increase plant availability and economic.The modeling simulates the plant performance in real time, and by performing enough simulation the expected long run performance of the plant can be estimated. The models have been built using ExtendSim which is a powerful Discrete Event Simulation software package that is ideally suited to the batch and semi-batch processes and events that occur within smelter operating environments. The value of performing this work is that the operational performance of the plant can be assessed ensuring production targets are met, without using excessive capital outlay."

Jan 1, 2013