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By Lionel Ryan

In 1996, the Dominican Republic operation of Falconbridge (Falcondo) developed a 5-year Process Control Plan in conjunction with the corporate Process Control group located in Sudbury, Ontario, Canada. This plan was further refined into an analysis of the areas of the highest potential economic return for the company with the reduction shaft furnace operation being the most promising. Historically, the reduction plant, which comprises 12 shaft furnaces, has been the bottleneck of ferronickel production. Since 1996 there has been a history of control development, and the current status is that all 12 furnaces are using advanced model-based multi- variable predictive control. The combination of advanced process control (APC), improved control system performance and improved process information management has resulted in an increased throughput of 6% per shaft furnace and a reduction in operating costs of 4.5 US cent/lb of Ni. This paper reviews some of the major milestones that have been achieved in this development Keywords: Advanced Process Control; Model Based Predictive Control; Connoisseur, Reduction Shatt Furnace; Nickel Laterite Ore; Ferronickel; MonitorMV

Jan 1, 2004

By Armin D. Ebner

A hetero-f1occulation model is developed to calculate the net force exerted on a paramagnetic nanoparticle that is moving in the proximity of a magnetite particle that is fixed or supported within an open flow and magnetically energized packed bed. Important variables investigated include the size and surface charge of the particles, the magnetic field, the ,flow velocity, the electrolyte concentration and the magnetic susceptibility of ,the nanoparticle. The ?influence: of other naturally occurring forces, such as hydrodynamic and DLVO(Le., van der Waals and electrostatic) forces on the magnetic attractive forces between the magnetite particle and the nanoparticle are also examined. This model reveals the feasibility of using magnetite particles instead, of stainless steel as the energizable element for high gradient magnetic separation.

Jan 1, 1999

By Ma Ying

The continuous directional solidification technique of five kinds of special ZA alloys with eutectic, peritectic and eutectoid transformation under the condition of continuous casting by heated mold was studied. The mechanism of surface defects appearing in ZA alloy line was discussed and the structure of some defects were analyzed by SEM. The results show that only when the fitting of various technique factors, pressure head, outlet temperature, pulling speed and cooling condition are reasonable under a certain range, can the ZA alloy smooth line be continuously pulled out. Unreasonable techniques will result in hot tear, rough surface, mush outlet, leaking and other defects. The shape and location of solid-liquid zone have an important influence on the formation of the above defects. When the solid-liquid zone is located in the mould outlet or inner mould, the surface of solidification will protrude into the inner mould. If the remaining liquid cannot counteract the solidification contraction, a rough surface will appear. If the solidification surface further into the mould, the ingot in the mould will have a great friction force when pulling and will form a hot tear. When the solid-liquid zone is moved out of mould, the solidification surface will turn into a plane, which easily results in leaking. A vibration or unstable operation will cause an ingot winding during pulling

Jan 1, 2003

By Yong Hack Lee

Nonferrous smelting processes have been through a rapid transformation since the beginning of 1980. The copper smelting technology has changed from the conventional Blast Furnace process to the Flash Smelting and MIB process. In the field of lead smelting, the technology has changed from the Blast Furnace Smelting to the Direct Smelting such as QSL and KIVCET. In 1992, Onsan Refinery successfully commissioned Direct Smelting QSL technology for lead. The QSL could produce more than 160,000 ton per year of lead bullion from lead concentrate and various residues. Moreover, since the year 2000, the TSL (Top Submerged Lance) Technology utilizing the same Direct Smelting process has been successfully commissioned to treat lead concentrate as well as lead sulfate residue produced from a hydrometallurgical zinc plant. This paper presents and compares the energy flows of lead smelting processes such as a conventional process and the Direct Smelting Processes plotted on the Pb-O-S phase diagram. The oxygen potential diagram suggests how to control the oxygen potential in the furnace. Also, it describes the recent operational experience in the TSL plant of Onsan Refinery with necessary mass balance of key elements.

Jan 1, 2003

By Yun Soon Han, Joo Hyun Park

Indium (In) solubility in the FeO-SiO2-Al2O3-5%CaO slag was measured under p(O2)=10¯¹¹ atm at 1573 K to clarify the dissolution mechanism of In in FeO-bearing metallurgical slag. The In solubility increased with increasing oxygen partial pressure, whereas it decreased by increasing the activity of basic oxide, viz. FeO. Thus, a dissolution mechanism of In in the FeO-SiO2- Al2O3-5%CaO slag was described by the following equation. In(s)+1/4O2(g)=(In+)+1/2(o2-) The enthalpy change of the In dissolution reaction was negative, indicating that the dissolution reaction was an exothermic reaction. This is consistent with the above reaction mechanism.

Jan 1, 2014

By Gabriel Riveros

Fire refining of copper consists of two stages copper oxidation and copper reduction. Very frequently the capacity of the anode furnace is determined by the rate of copper reduction, The analysis of factors affecting the rate of the oxygen reduction from a liquid copper with solid carbon or injected hydrocarbons pointed out the role of the mass transfer in a liquid copper in final stage of the reduction. Experimental results of copper reduction with graphite and injected natural gas in laboratory-scale crucibles showed two stages of the reduction process with a sharp change of the controlling mechanism. The estimated dynamic surface area of gas bubbles based on the measured bubble frequency and the gas flowrate allowed for the determination of the reaction constant as a degree of the partial pre-combustion of the air/natural gas mix. The variation of the used reductant as a function of the oxygen concentration and temperature has been evaluated based on the determined kinetic model. The intensification of copper reduction in fire refining has been discusses on the basis of obtained kinetic data and analysis of various factors determining the time of reduction.

Jan 1, 2003

By Douglas J. Harvey, Chi-Mou Ni

"This paper presents an analysis technique for the solidification of metal castings. This method, based on a modified finite difference scheme with an irregular mesh, is capable of dealing with the complex geometries of castings. The nonlinearities in material properties of specific heat and thermal conductivity, arising from the phase change during solidification, are accounted for in the step-by-step calculations. Two solidification problems are solved with this analysis technique and the calculated results compare satisfactorily with experimental data. IntroductionCasting process design engineers are often faced with the difficult problem of designing castings to be produced porosity-free. Since the solidification of metal is affected by many interacting variables such as the thermal conductivity, density, and specific heat of both the molten metal and the mold, it is easily seen why this is a difficult task.Typically, casting tooling design is an intuitive process which builds on past successful methods. After processing equipment is constructed, trial castings are made and examined for dimensions and integrity. Changes in the tooling are generally required to improve casting soundness or to reduce cycle time. In the permanent mold process, tooling is complex and difficult to alter after initial construction. The water-cooled steel molds are part of the complete automated system. Associated holding furnaces, pouring ladles, casting conveyers, and utility connections all make other than minor adjustments a costly and time consuming task. An analytical method for using the principles of heat transfer for predicting solidification patterns would be of great value in the permanent mold process by minimizing costly changes."

Jan 1, 1986

By Thomas J. Keefe, O&apos

The effects of cobalt, B-naphthol, glue and antimony on the polarization behavior of zinc sulfate electrolyte were investigated. It was found that B-naphthol was beneficial in reducing the detrimental effects of cobalt while antimony and excess glue were each harmful. Since the nu cl eat ion over potential was insensiti1ve to coba1t, other regions of the polarization curve were used to indicate electrolyte balance. The low? current density area occurring in the reverse or anodic sweep direction was? often an indicator when an ?unstable condition existed. The two parameters evaluated were the degree of inflection in the polarization curve in the low current density region during scanning and the rate of current rise observed when the sample was potentiostated at -0.781 Volts (SHE). Using this technique, a two-additive system was shown to be desirable to control cobalt and antimony containing electrolytes. The structure of the deposits was examined using scanning electron microscope techniques.

Jan 1, 1985

By Karen Tempel

Newmont's Lone Tree Mine is located 30, miles east of Winnemucca in Humboldt County, Nevada. Starting in February 1994 a pressure oxidation circuit was commissioned to treat refractory gold ores. Gold is leached and recovered from the oxidized slurry in a six-stage carbon-in-leach (CIL) circuit. Lone Tree has been able to maintain tighter control' of cyanide addition and reduce cyanide consumption its CIL circuit through the installation of Degussa's Cyplus® CCS Cyanide Control System in the spring of 2000. 'The Cyplus® CCS, along with additional inputs' from plant sensors, has allowed tor a more efficient and effective control strategy over the manual control method used ,in the past. This paper documents the key aspects of the Cyplus® CCS installation; the development of the control strategy, and the benefits achieved from enhanced control.

Jan 1, 1998

By Marcelo B. Mourão

The reduction of iron ores by solid carbon, when both are agglomerated together in the form of pellets, has important kinetic advantages. Although several studies have been performed on the subject, some points on the controlling mechanisms need clarification. There is a big scatter in the values of the apparent activation energy reported in the literature, and this may be due to factors like heat transfer, flow of gases in the reduction system, pellet size and composition. This work is concerned with the effect of several parameters on the reaction rate. The parameters studied were temperature (in the range 1173 K to 1423 K), carbon type (coke or charcoal), pellet size, gas flow rate, catalyst action of the produced metallic iron and added sodium carbonate. It has been shown that the values of the apparent activation energy can change according to the reduction conditions employed, and hence any modeling effort will have to take account of these parameters. EPD Congress 1994

Jan 1, 1994

By J. Winters, L. Vos, C. Canoo

Committed to a sustainable development of zinc applications, Union Miniere is investigating processes for the minimisation of waste and residues originating from the classic hydrometallurgical zinc process. In that context, Union Miniere has developed a method for the cold inertisation and solidification of goethite, the Graveliet® process. The result is a hard and inert gravel that can be used in the building industry. During the past two years, a pilot plant for the production of Graveliet® has been built and operated. In the present paper, the Graveliet® process and the pilot plant are described after which the properties of the produced gravel are discussed, from both a mechanical and an environmental point-of-view. Graveliet fulfils the criteria for use as a secondary building material. The GravelietJ process is a viable technology to avoid stockpiling of goethite residues and it thus assures the long-term development of the hydrometallurgical zinc process.

Jan 1, 2000

By Kent D. Peaslee

When supersonic oxygen jetting is used in electric furnace steelmaking, the lance jet axis is typically inclined at larger angles to the vertical than is used in basic oxygen steelmaking. The supersonic jet is important not only for refining the steel, but for sustaining the foamy slag in the electric furnace. Physical modeling was carried out using a room temperature, two-dimensional slice apparatus in which mercury represented the metal and water-glycerol the slag. High speed video photography with image analysis was used to study the effects of the angle of inclination on the slag/metal bath. Mathematical modeling using FLUENT provided a method of predicting flow patterns and the trajectories of drops injected at various points in the flowfield. A one-half scale water model of the system, in which lance heights, angles, and flowrates simulated those encountered in steelmaking operations, was used to provide a better understanding of some aspects of the oxygen blowing process in electric furnace steelmaking.

Jan 1, 1994

By Kai Kang, Jun Bao, Shouping Liu, Xiao Sun

Powder characteristics have a significant influence on selective laser melting (SLM) process. In this research, particle size, surface contour and the microstructure of IN718 powder used in SLM were tested, and the physical and chemical changes during heating process of the powder were investigated as well. The shape characteristic and fluid properties of IN718 powder were defined and measured. It is shows that most particles of IN718 powder exhibited nearly spherical shapes, and the particle size is about 22.95μm. On this basis, IN718 sample was fabricated by SLM process using the powder and the microstructure of the fabricated sample was investigated. The results indicated that the sample has a dense microstructure, no macro-defects but a few micropores and porosity. Compared with the powder, there was no new phase formed in the sample and melting point of the sample was little less than that of the powder.

Jan 1, 2015

By M. J. Bagshaw, J. D. Hunt, R. M. Jordan

"Continuous casting processes, and the roll casting process in particular, offer considerable potential to the Aluminium industry, both meatallurgically and economically.The three major limiting process problems that occur during roll casting are Centre Line Segregation', 'Sticking' where metal adheres to the rolls during casting, and 'Heat Line' formation. 'Heat Lines' are localised semi-continuous longitudinal defects, usually a few cms in width, where the cast metal leaves the roll bite partially molten. These defects occur at relatively low casting speeds when the mean slab exit temperature remains several hundred degrees below the solidus temperature. The objective of the work described here is to develop a better understanding of the roll casting process in general, and in particular, to understand the phenomenon of 'Heat Line' formation.A steady state two dimensional finite difference model has been developed to describe the roll casting process, incorporating a variable heat transfer coefficient through the roll bite. In the model the difference equations are formulated using a control volume method and latent heat is incorporated according to the Scheil equation. A Gauss-Seidel type technique is used to obtain the solution. Because the rate of heat evolution is non-linear the temperature in each box is determined by using a Newton-Raphson method. The solution for a box can be multi valued and therefore lead to instability particularly near the vicinity of the front. A stability 'criterion is presented which shows that to obtain a stable solution it is better to have long narrow boxes rather than boxes with small dimensions in both directions.The model explains why heat lines form in terms of the variable slab/roll heat transfer coefficient.Experimental measurements of slab exit temperatures are also presented. These were obtained on a Hunter twin roll caster for the binary AI-Cu system, at two compositions over as wide a range· of casting speeds as possible. The experimental results are compared with the predicted ones."

Jan 1, 1986

By Youn-Bae Kang

In order to overcome weak points of steel for its engineering applications, in particular, for environmentally benign, energy-efficient, lightweight engineering systems, a number of new steels have been proposed, especially to improve strength-to-weight ratio (specific strength). Mass production of these steels, however, has encountered a serious roadblock particularly in the steel refining and casting processes. This is because their chemistries and cleanliness requirements are vastly different from those of the conventional steels, and thus an incremental improvement of the prevailing process technologies is found hard to meet the requirements. In this study, a new process is proposed, which employs inert gas bubbles in the shroud nozzle, liquid steel drops in the degassing chamber, and the siphon transport for continuous casting. The proposed process which integrates the final refining and cleaning steps prior to casting is expected to be a technologically disruptive innovation on the conventional counterpart. The effectiveness of the individual steps is discussed with experimental results.

By Yun Li

In 1999 Yunnan Copper Corporation (YCC) decided to modernise their copper smelter and change the existing sinter plant I electric furnace process to a combination of ISASMEL T and electric slag cleaning furnace. The main aim of the project was to improve the environmental performance and decrease the energy consumption. Generally the project has been successful, partly attributable to the selection of a reliable and fully demonstrated technology. The design capacity for the ISASMELT furnace is 600,000 tonnes of dry copper concentrate per year. The furnace has been running smoothly since heat up in May 2002. YCC expended considerable effort in the preparation for plant operation. An extensive training program for key YCC personnel at the Mount Isa Copper Smelter improved their understanding of the process significantly and ensured successful hand-over of the technology. This paper describes the project history and summarizes initial operating results.

Jan 1, 2003

By R. W. Bartlett

A two step process for treating platinum group metal flotation concentrates Is described while experimental results. The process was designed to be simple and Inexpensive While yielding a high recovery and fast turnaround. Ii consists of electric furnace smelting of concentrate to remove gangue and produce a homogeneous sulfide matte containing all of the base metals and platinum group metals. Sulfide oxidation Is minimized during smelting to avoid Installing an acid plant In the second step, matte Is pressure-leached with oxygen In an acid sulfate system to dissolve Iron, nickel, ?and copper while leaving a residue highly concentrated In precious metals, and typically about 1% of the flotation concentrate mass, A batch process with oxygen titration against the base metal composition of the feed Is used to control the end point of the leach. Sulfides must be eliminated while minimizing the precipitation of hydrolysis products. The leach residue can be smelled to bullion to facilitate sampling accuracy.

Jan 1, 1989

By Gabriel Riveros

Fire refining of copper consists of two stages copper oxidation and copper reduction. Very frequently the capacity of the anode furnace is determined by the rate of copper reduction. The analysis of factors affecting the rate of the oxygen reduction from a liquid copper with solid carbon or injected hydrocarbons pointed out the role of the mass transfer in a liquid copper in final stage of the reduction. Experimental results of copper reduction with graphite and injected natural gas in laboratory- scale crucibles showed two stages of the reduction process with a sharp change of the controlling mechanism. The estimated dynamic surface area of gas bubbles based on the measured bubble frequency and the gas flowrate allowed for the detennination of the reaction constant as a degree of the partial pre-combustion of the air/natural gas mix. The variation of the used reductant as a function of the oxygen concentration and temperature has been evaluated based on the detennined kinetic model. The intensification of copper reduction in fire refining has been discusses on the basis of obtained kinetic data and analysis of various factors detennining the time of reduction.

Jan 1, 2003

By Micheal McCarter, Biswadeep Saha, Meenakshisundaram Ramanathan, Chai Ren, Sivaraman Guruswamy

"Three-point bend test was used to study the effect of electrochemically charged hydrogen and magnetic field on the embrittlement behavior of AISI 4340 steel in this work. Acoustic emission signals were collected during the test and analyzed to gain an understanding of the crack growth process. Cathodic hydrogen charging in AISI 4340 steel resulted in drastic reduction of ductility and strength. Hydrogen embrittlement was characterized by a change in fracture surface from dimpled ductile surface to quasi cleavage type fracture. No significant effect was observed in the presence of magnetic field. The acoustic emission signals collected during the test provided an indication of the extent of energy released during the crack growth process.*Support of this work by NSF through the award DMR-0854166 is gratefully acknowledgedIntroductionGrowing interest in hydrogen as a clean fuel and use of steel and other iron based alloys for storage and transport of hydrogen has led to extensive study of the influence of hydrogen on the mechanical properties of these alloys. Hydrogen interaction with materials may result in degradation of mechanical properties. Embrittlement, either ductile or brittle, can be described as a condition which decreases the toughness of the material or increases the ease of crack growth. Hydrogen present even in few parts per million is sufficient to embrittle steels at room temperature [1]. In most cases, hydrogen exposure is through an electrochemical process in aqueous corroding environments. In such cases, they are prone to be exposed simultaneously to electrically induced magnetic fields, which are also believed to affect the hydrogen embrittlement susceptibility of these alloys. So it is also important to study the effect of magnetic field on the hydrogen embrittlement susceptibility. Hydrogen solubility by electrochemical process in aqueous solution is proportional to square root of current density for iron. [2,3]"

Jan 1, 2012

By J. B. Winter

The present Inspiration Consolidated Copper Company Smelter/Acid Plant complex located near Miami, Arizona, was designed and built specifically to conform to the ambient air quality standards imposed by the Federal Clean Air Act of 1971. The present plant replaced a facility which had been in operation since 1915. The electric furnace, siphon converters and acid plant complex were commissioned in May, 1974 (1). At that time, the Plant was considered to be one of the most extensively monitored and instrumented facilities of its kind in the world. Several control areas were located in close proximity to the controlled process, in addition to so-called central control rooms in the Smelter and Acid Plant. The control rooms were staffed with officials below the foreman level. Instrumentation consisted of conventional analog devices, except for a computer used in monitoring ambient air environmental conditions and limited use of programmable logic controllers. The harsh service conditions prevalent in the plant rendered a significant portion of the instrumentation unreliable and, in many cases, inoperable. Failure of the facility to obtain the total sulfur collection for which it was designed was, in part, due to serious inadequacies in control system logic and sulfur recovery averaged 79% in the early years. After careful study of the smelting process, engineering hardware and high labor cost inherent in the organizational structure, management made a judgement decision to convert to centralized control of the process with high level supervision 24 hours per day. A distributed digital control system with supervisory arid data acquisition/information reporting computers was selected to satisfy the requirement of central control. Operations are now controlled and coordinated from a primary control room in the Smelter and a satellite control area in the Acid Plant.

Jan 1, 1983