Search Documents

By D. W. Ashman

The zinc pressure leaching plant at Cominco's Trail Operations is now in its ninth year of production. The plant produces a zinc sulphate and jarosite slurry which is further processed in the calcine leaching circuit. Elemental sulphur, a by-product of the process, is sold in the North American market. During the past eight years, a number of changes have been made to the plant to remove known production bottlenecks and to improve leaching extraction. These changes have raised production rates above the initial design so that the plant currently accounts for approximately 20 percent of Trail s zinc production. These rates are expected to be increased further upon the completion of the alterations currently in progress. The knowledge gained over the operating life of this plant has allowed Cominco to plan for a possible future expansion of the zinc pressure leaching plant. If expanded, zinc pressure leaching would account for approximately 48 percent of cominco?s zinc production.

Jan 1, 1990

By Ludovic Charpentier

Production of metallic wires directly from liquid jets would avoid drawbacks of extrusion (space needed, damaging, cost?) and enable recycling. But liquid jets tend to break, due to capillary instabilities, unless a solid layer (coating or start of solidification) surrounds it. We recently developed a process to produce tin wires, cooled by water flow parallel to the jet. Superficial oxidization of tin produces a glass coating around the jet. Studies showed the length of wires increased when increasing speed of tin jets, and that water average speed should be the closest possible to the jet one to have smooth fibers. Producing 1 mm diameter wires is possible. The length of wires is limited by the experimental setup, which does not provide possibilities to coil the wire. Most of other metals do not generate glass-like oxides. The lack of coatings makes it necessary to reduce the capillary instabilities to obtain fibers.

Jan 1, 2006

By Akira Yazawa

Experimental results for the distribution ratios of various elements between the slag, matte and/or copper in the silica-saturated copper smelting system were summarized. The experiments were carried out under an oxidative smelting condition with S02 gas flow, and also a reductive smelting condition equilibrating with metallic copper or iron. To evaluate the results thermodynamically, the availability of one atom cation base expression for the constituent compounds is emphasized from both of theoretical and practical standpoints. Both of oxidic and sulfidic dissolutions in slag are postulated for some elements such as copper, nickel and lead., and the experimental results are reasonably explained thermo-dynamically. The results for the mutual solubility between matte and ferrite slag and the distribution of minor elements between liquid copper and ferrite slag are also discussed.

Jan 1, 1983

By Robert M. Leary

The Kennecott Utah Copper smelter operates two Outokumpu flash furnaces: a smelting furnace for production of high-grade matte and a converting furnace for production of blister copper. Flash furnaces typically possess several characteristic features that must be considered in process control development such as long lag times associated with settler volume, non-linear input and output responses, large process gains, and unmeasured disturbances. Additionally, the Kennecott smelter possesses certain unique characteristics which must be considered such as single mine concentrate source, limited concentrate blending capacity, and feed preparation facilities that inevitably cause significant lags between furnace control parameters and manipulated set points. In order to improve furnace control and on-line time, a process control system was developed to address these issues. The feed forward control module provides predictive control and operates in response to furnace feed input changes. The feed back control module provides responsive control and is based on furnace output deviations. To provide regular feed back information to the control room supervisors, new sampling methods were developed which provide the operators with molten metal and bulk material samples at regular intervals to provide information for control. The control system was implemented on the Flash Converting Furnace in May 1999 and on the Flash Smelting Furnace in August 1999.

Jan 1, 2000

By John A. Thorpe, Gary R. Maxwell, Kirk M. Schall, Kenneth A. Brunk

"Gold ores containing oxide and some sulfide copper minerals incur significant cost penalties when leached with cyanide, because 4-5 moles of cyanide are consumed for each mole of leached copper. This equates to ~4 kg of NaCN per kg of leached copper. Total cost of excess NaCN consumption plus CN destruction can exceed $4.00 per tonne of ore. AuGMENT Technologies has patents pending on a process that can 1) economically recover 70-80% of the cyanide that is fed to a mill, 2) produce salable copper cathodes, and 3) reduce the need for a cyanide destruction facility. Standard equipment for resin processing and electrowinning are used to recover the cyanide and produce the copper cathodes. Steps have been taken to determine: 1) how to develop the resin kinetics, 2) how much savings are incurred at a mill site, 3) how the novel 'electro-elution' circuit achieves efficient operation.IntroductionWhen gold ores containing nuisance copper are leached with cyanide, a significant cost penalty is incurred because 4-5 moles of cyanide are consumed for each mole of copper that leaches. This is equivalent to the use of -4 kg of NaCN per kg of copper that leaches. The total cost of excess NaCN consumption plus cyanide destruction can exceed $4.00 per tonne of ore.AuGMENT Technologies has a patent pending on a process that can 1) economically recover 70-80% of the cyanide that is fed to a mill, 2) produce salable copper cathodes, and 3) reduce the need for a cyanide destruction facility. This ACCS (Au-.C.u-.C.N Solution) Process Technology involves the novel application of copper cyanide chemistry. Standard resin processing and electrowinning equipment are used to recover the cyanide and produce the copper cathodes."

Jan 1, 1997

By Kamal Adham

Hydrochloric acid is used as lixiviant in such hydrometallurgy processes as synthetic rutile production and nickel extraction. The intermediary metal chloride is normally roasted to release gaseous HCl and a solid metal oxide. A large amount of fuel is required for this thermal regeneration, mainly to vaporize the water content of the feed solution. To conserve fuel, some energy recovery from the off-gas is currently achieved, but the fuel costs can further be reduced by process optimization and energy recovery from the gaseous, aqueous and solid products of the regenerator. Here, first the existing limitations to fuel efficiency in the industrial scale HCl regeneration roasters are described. Then, for the case of a dilute feed solution, options for pre-evaporation and fuel minimization are modeled and compared. Finally, energy recovery technologies including heat pumps, acid heat exchangers and solid waste heat boilers are described, and their potentials as the heat source for pre-evaporation of the feed are evaluated.

Jan 1, 2003

By Paykan Safe

Computational Fluid Dynamic (CFD) modeling provides a powerful tool to assist with the design of ventilation and fume control systems in smelters and other high temperature metallurgical facilities. For this paper, this tool has been used to analyze the off-gas flow patterns exiting the mouth of a Peirce-Smith converter into a water-cooled hood and drop out box. The effects of various process and physical plant design parameters on process gas and fume capture and potential build up on the converter hoods was examined, and the optimum design and operating parameters were determined.

Jan 1, 2000

By He Zhi-jun, Ning Zhe, Pang Qing-hai, Zhang Jun-hong, Zhan Wen-long

In this study, Raman spectroscopy was utilized to investigate the evolution of char structure in pulverized coal (PC) during microwave irradiation. The results indicated that though microwave treatment was carried out at low powers of 132W or 264W, significant variation in char structure was still observed. Char structure turned out to be more irregular firstly under microwave irradiation. However, char structure of superior regularity was obtained with the extension of irradiation time. It can be conclude that short time microwave treatment may facilitate the chemical activity of coal, while long time microwave irradiation on PC may deteriorate its combustion or pyrolysis property.

Jan 1, 2016

By J. R. Addison

Commissioned in September 1987, the Phelps Dodge Morenci, Inc. (PDMI) Central Electrowinning (EW) Tankhouse bas undergone two major expansions in its eleven-year history. A third tankhouse renovation, which began in November 1998, entails complete conversion of the 548-cell facility from a copper starter sheet based operation to Mt. Isa Process stainless steel mother blank technology. This paper outlines the operating history of the Central EW Tankhouse and reviews the conversion process, the rationale that led PDMI to undertake this project, and describes various design optimizations which have been implemented during the conversion.

Jan 1, 1999

By W. G. Davenport

A survey of world copper refining tankhouse .practices has been carried out. This paper compiles the results and examines changes in operating practices .since the similar 1987, 1991 and 1995 surveys. Continuing trends are the installation of ISA Process and Kidd Process stainless steel cathode technology, polymer concrete cells, anode preparation machines and automatic cranes. Instrumentation and automatic control are increasing, particularly for addition agent optimization; solvent extraction .and ion exchange techniques are being increasingly applied for electrolyte purification. The overall consequences of these changes have been 'improved cathode purities and enhanced tankhouse productivities.

Jan 1, 1999

By Xiang-ning Meng, Miao-yong Zhu

"A three-dimensional finite-element heat-transfer model is conducted to predict temperature of hot copper plate in a slab continuous casting mold and the effect of casting speed on temperature difference between copper plate and solidifying shell is simulated in combination with process data. The results show that centre temperature of hot copper surface at casting speed 1.8 m·min-1 and 2.0 m·min-1 are higher than that of 1.6 m·min-1 casting speed 4.7-5.2 °C and 11.2-12.2 °C respectively and temperature is not increased linearly with casting speed. Temperature difference in meniscus between mold and shell is influenced obviously by casting speed and increased 4.0- 6.0 °C with increment of casting speed 0.2 m·min-1• Fluctuation of temperature difference in meniscus is a main reason to deteriorate casting quality as increasing casting speed.IntroductionIn conventional continuous casting of steel, a large amount of sensible and latent heat of molten steel dissipates in primary cooling zone and mold becomes a critical component of caster to govern steel quality, meanwhile, thermal load on mold is increased constantly and environment is also more abominable since high productivity and quality are required and high-effective technologies are applied. So, an in-depth understanding of thermal behavior of mold at high casting speed is essential to design cooling structure and maintain casting stability. Many studies have been carried out to shed light on thermal behavior in mold. Chow et al. [l] applied a mathematical model to heat transfer in billet mold at a high casting speed to give a new taper in order to minimize mold-strand interaction. Thomas et al. [2] researched relation between mold geometry and temperature distribution based on a finite-element heat-transfer model. Lu et al. [3] indicated that slab mold temperature are mainly affected by thickness of copper plate and nickel layer by a heat transfer model. Samarasekera et al. [4, 5] researched temperature of copper plates for both billet and slab molds and effect of a large number of factors ranging from water quality to casting speed. Park and Thomas et al. [6, 7] developed a finite-element thermal-stress model to determine temperature and thermal distortion and stress in both thin and slab molds and O'Connor et al. [8] applied an elastic-plastic-creep finite-element model in a funnel shaped mold to achieve same goals. Cicutti et al. [9] evaluated heat transfer and temperature fluctuation in a slab mold and proposed an expression to predict global heat flux as a function of process parameters and an index to quantify thermal instability. All mentioned above shown that thermal behavior is not only important to casting stability, it is also premise to further understand mechanical behavior in mold."

Jan 1, 2011

By Pengfu Tan

Converter slag chemistry control has played an important role in optimizing converter operations. A thermodynamic model of copper P-S converter has been developed to predict the behavior of magnetite in the converter slag. Predictions of bath temperature, slag and matte compositions, and magnetite content in the slag have been validated by industrial data. The effects of fluxing strategy, returns and skim charges, oxygen enrichment, and temperature on the magnetite formation in the slag have been predicted and discussed. Some improvements of the industrial operations have been presented.

Jan 1, 2005

By Xiaojian Zuo, Yihua Han, Qingguo Xue, Jingsong Wang, Lintao Wang, Rongzong Lan

"Using the facility of reduction experiment, the low temperature reduction pulverization and reduction behavior of sinter in oxygen blast furnace (OBF) were studied. Through analyzing the results, the difference of pulverization and reduction behavior of sinter in OBF and conventional blast furnace (BF) were discussed. Furthermore, the effect laws of reduction temperature and the content of CO and H2 on reduction behavior of sinter were studied. Also the controlling step of iron oxide reduction was discussed. Compared with BF, the low temperature reduction pulverization of sinter became serious at 773 K; reduction rate became faster at 1173 K; reduction time became less and final reduction degree was increased in OBF. With increasing of H2 and CO contents, the reduction of sinter was promoted. The reduction process was controlled by interface chemical reaction at the earlier stage and by interface chemical reaction and internal diffusion at the final stage.IntroductionThe new ironmaking technology of Oxygen Blast Furnace (OBF) is most likely to be used in large-scale application process. The concept relies on the removal of the CO2 contained in the top gas of the blast furnace. Therefore the useful components, i.e. CO+H2, can be recycled back into the furnace and reused as reducing agents. In addition, injecting oxygen (O2) into the furnace instead of preheated air, removes unwanted nitrogen (N2) from the gas. Under the pressure of CO2 emissions in iron and steel making, the growing international shortage of coking coal resources and the rising price of coke, OBF has attracted attentions of both domestic and foreign researchers, because it has so many advantages such as high productivity, high PCI rate, low coke rate, high gas reducing capability and high top gas calorific value, etc [1-7]. As a result of recycling most of the top gas after CO2 removal and injecting oxygen into the furnace, the reduction capacity of blast furnace gas will be increased, so the metallurgical behavior of OBF's iron burden is different from traditional blast furnace. Therefore, it is one of the keys to develop this technology, which studies the metallurgical behavior of sinter in OBF. The purpose of this paper is to study the low temperature reduction pulverization and reduction behavior of sinter at the atmosphere of OBF, which includes the difference of low temperature reduction pulverization and reduction behavior of sinter in oxygen blast furnace and conventional Blast Furnace (BF). It will provide theoretical basis for the development of OBF."

Jan 1, 2012

By M. T. Baquera

A comparison of microstructures associated with W single-crystal ([001], [011], [111]) rods prior to deformation (as grown), and after quasi-static compression (at a strain rate of ~1/s) by transmission electron microscopy (TEM) shows several orders of magnitude difference in dislocation density. Dislocation substructures were not significantly different amongst the deformed sample orientations. In contrast, [001] W rods penetrated into steel targets, at impact velocities of ~1.3 km/s, exhibited heavy dislocation densities and dynamic recrystallization as very distinct microstructural regimes accommodating the penetration process. Twinning on {112} also occurred as a precursor to, or remnant of, these microstructures near the projectile head. These results suggest that deformation accommodating the extreme strains and strain rates associated with the penetration of a single-crystal rod into a metal target is not adequately represented by conventional deformation

Jan 1, 2006

By T. W. Gonzales

The refractory performance of Peirce-Smith converters is considered to be mainly determined by effects of process control and refractory installation design. BHP Copper has shown that, over the last four years, considerable improvements in tuyere line life can be affected .by maintaining a uniform temperature in the operating converter and by ensuring sufficient and specific placement of expansion allowance in the construction of the refractory brickwork. A combination of optimized crane availability, rapid matte transfer, converter operating practices, new refractory installation techniques and applications has minimized out-of stack time. In addition, larger diameter tuyere pipes and hard piping have increased blowing rates and lowered cycle times, which has resulted in a tuyere line performance in excess of 62,500 tonnes of blister copper before maintenance is required. This paper discusses the refractory installation design changes that were made to increase tuyere line life.

Jan 1, 1999

By Aarne Kopanen

In recent years, various renovations have been carried out in the production chain of the Outokumpu copper refinirg process. The anode casting shop, which is the final integral production section at the Harjavalta copper smelter built in its original form in 1945, was fourxl unsuitable for technical and capacity demads during longer periods of operation, and a new casting shop was built in 1974. The electrolytic copper refinery of Outokumpu Oy at Pori was built in 1941, and subsequently expanded in two stages. Even with its present limited scale of production it has been fom important to mechanize the main operations. This work was started in 1967 with the design and construction of the starting sheet machine connected with the cathode washing and unloading machine as a combined unit. Mechanized treatment of anodes has gained advantage particularly from the new design of a highly automated anode casting shop. In the further development of the mechanization a stripping machine for, starting sheets was designed and installed, starting operation in 1974.

Jan 1, 1976

By D. D. Harbuck

The U.S. Bureau of Mines recently identified a significant new source of scandium in an Oklahoma tantalum waste residue (approximately 0.24 pct Sc). Because scandium is a strategic and critical metal which the Department of Defense has classified for special consideration, the Bureau is researching methods of recovering scandium and associated metals from this and other process residues. A variety of operating parameters were evaluated to determine the best technique for recovering scandium. Testing showed that by sulfating the residue at temperatures as low as 150' C for reaction times as short as 0.5 hr, over 94 pct of the scandium converted to a water soluble form. Solvent extraction using DEHPA selectively recovered 100 pct of the scandium from the water leach solution.

Jan 1, 1992

By Leijun Li, M. M. Mahapatra

"A three-dimensional finite element model with moving heat source was developed for pulsed-laser powder deposition (PLPD) process. Experiments were conducted to study the repair of superalloy components using the PLPD process. During the experiments, IN 625 powder was deposited on a superalloy substrate similar to IN 738. The process was modeled using three-dimensional finite element analysis. Element birth and death technique was used in the finite element model for simulating the deposition of powder layer on the substrate. A moving distributed heat source was used in the thermal model for realistic simulation of the process. Temperature dependent thermal material properties including enthalpy were used for the powder and the substrate in the transient thermal analyses. The fusion zones and peak temperature distributions of the deposits were predicted from the transient thermal analyses.IntroductionPoor weldability is a critical issue of superalloy repairing. The microstructural directionality of the superalloy components are disrupted when repaired by the fusion welding processes. Currently there is no widely accepted method to economically and reliably repair directionally solidified superalloys components. Pulsed laser powder deposition process (PLPD) is a promising repairing technique as the substrate is not severely affected by the heat source.In this study PLPD technology is used as the tool for superalloy repairing. In most of the land based turbine engines the directionally solidified nickel based superalloy similar to IN 738 [1] is used as the bucket material. The turbine engine blade tips are subjected to a combination of extreme operating conditions and corrosive environment. The tip of the nickel based turbine engine blades can be repaired using IN 625 material as suggested in the literature [1-2]. IN 625 is considered to be ductile and strong enough for the purpose of Ni based turbine engine blade tip repair[1-2]. During the present PLPD investigation, IN 625 powder was used as the deposit material on an experimental super alloy substrate similar to IN 738 superalloy used as the cast superalloy for the turbine engine blades."

Jan 1, 2012

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 D. B. Dreisinger, V. van der Pas

Zinc sulphate electrolyte used for zinc electrowinning must be purified for cObalt ions. The cobalt is removed in a cementation stage by the addition of zinc dust. Copper arid antimony are frequently used additives which enhance the cementation of cobalt. This paper aims at a better understanding of how copper and antimony promote the removal of cobalt. Initial experiments were done in a batch cementation reactor. Copper and antimony precipitated in the early stages of cementation indicating that a preferential substrate was formed. The individual role of copper and antimony was further investigated in an electrochemical cell. On a microsca1e, the , growth process, morphology and the composition of the precipitates were examined with SEM and XRD. It was found that cobalt could not be deposited in its pure form but as a cobalt-zinc alloy with zinc as the prime constituent. Copper increases the cathodic surface area of zinc dust by precipitating as numerous dendrites. Antimony acts as a cathodic surface onto which a cobalt-zinc alloy with an increased cobalt content is deposited.

Jan 1, 1997