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By Mark Jolly

"Instead of using the traditional batch casting process, the CRIMSON [1] (Constrained Rapid Induction Melting Single Shot Up-Casting) method employs a high-powered furnace to melt just enough metal to fill a single mould in a closed crucible. The crucible is transferred to a station for computer-controlled counter gravity filling of the mould for optimum filling and solidification. The CRIMSON method therefore holds the liquid aluminium for a minimum of time drastically reducing the energy losses attributed to holding the metal at temperature. With the rapid melting times achieved, of the order of minutes, there isn’t a long time at temperature for hydrogen to be absorbed or for thick layers of oxide to form. The metal is never allowed to fall under gravity and therefore any oxide formed is not entrained within the liquid. Thus higher quality castings are produced leading to a reduction in scrap rate and reduced overall energy losses.IntroductionEngineers at the University of Birmingham, England, with local company, NTec, have invented a new casting process that will reduce the energy costs of light-metal foundries. The technology, entitled CRIMSON, means that foundries need only heat the quantity of metal required to fill a single mould rather than large batches that use unnecessary energy and create waste. The complete concept of CRIMSON requires a change of philosophy in the approach to casting and requires the user to think holistically in order to reap the full benefits from the process. This paper will discuss the various aspects of energy wastage within the foundry sector and discusses the processes whereby the energy can be reduced. Primarily the author focuses on the aluminium sector but CRIMSON can be applied to many of the non-ferrous “light” alloys. Ferrous materials and non-ferrous “heavy” alloys can also benefit from some of the ideas but not necessarily directly from the application of CRIMSON."

Jan 1, 2010

By I. M. Santos Moraes

Achieving high current efficiencies when operating at high current densities is a goal for every refinery, whether conventional or permanent cathode technology is employed. To obtain higher current efficiency at increased current density at Caraiba's Tankhouse, the production team decided to change the cathode cycle from eleven to thirteen days, reducing cathode cycle to one per anode cycle. The idea was to reduce the anode-cathode spacing and consequently reduce the potential for short-circuiting them. With respect to current efficiency, the overall result was not much better than that obtained with the normal operating conditions. A new attempt to obtain higher current efficiency at high current density was implemented by going back to two cathode cycles per anode cycle, this time reducing cathode life to ten days. This approach yielded the highest current efficiencies. This paper presents the data generated with the three operating conditions: normal practice, a single cathode cycle per anode cycle, and two cathode cycles per anode cycle with a reduced cathode cycle time. It compares the productivity achieved with each set of operating conditions. An analysis of the main operating parameters as well as the advantages and disadvantages involved with each condition is also presented for future reference.

Jan 1, 1999

By I. H. Bonekamp

Norddeutsche Affinerie has operated an Outokurnpu type flash smelter for more than 25 years. In recent years, the concentrate smelting capacity was increased to 750,000 tpy, double of the initial design capacity. Maintaining this high performance level requires very good metallurgical process control. It is not enough to base this control on thermodynamics and kinetics since the furnace is highly dynamic. Understanding these dynamics and being able to quantify them can have significant financial benefits. A mass and energy balance model was developed and is discussed based on measured data. At this time the model is based on the major elements copper, iron, sulfur and silica. With it is possible to quantify the differences of the various material streams such as matte, slag, flue dust, matte carry-over to settling furnace, etc. Comparing the reconciled energy balance model with the fundamental thermodynamic model makes it possible to quantify the dynamics. These dynamics are related to input parameters using methods such as statistics and neural nets. In the future this database will be used to improve the understanding of the dynamic process as well as the dynamic process control.

Jan 1, 1999

By David G. Dixon

A mathematical model is derived in dimensionless form which simulates the effluent concentration response of reagents from spent heaps under both fresh and recycled water rinsing. The model is based on dispersion from isochoric pathways distributed in length and cross-section, oriented normal to convection channels in ideal plug flow. The effects of heap height, rinsate flow, and initial reagent concentration are examined. It is shown that the rinsing cycle undergoes a distinct shift between fast and slow rinsing at a certain time depending on the amount of stagnant solution in the heap, and the distribution of dispersion pathways. Results of preliminary column rinsing tests on both agglomerated and unagglomerated ores are presented which partially validate the model.

Jan 1, 1994

By Józef Czemecki

Polish copper concentrates are characterized by high levels of impurities, particularly Pb and As. Two technologies are being used for copper concentrate smelting at KGHM Polska Meidz S.A., namely the shaft furnace process (Legnica Copper Smelter, Glogów I Copper Smelter) and a single-stage process for direct to blister concentrate smelting in a flash furnace (Glogów II Copper Smelter). Both technologies are used at different physical and chemical conditions which results, in different impurities behavior. The paper presents flow sheets for copper production in a plant using the shaft furnace process and in another in which a single stage flash process is used. The metals distribution in particular semi-products is given as well as a method for elimination of impurities from the copper production cycle. Methods are also discussed for alloy and matte converting and copper refining to obtain low Pb and As concentrations in anode copper (0.3% Pb and 1500 ppm As maximum) that are being used in the KGHM Polska Meidz plants. Useful co-operation between the plants using different technologies, aimed at the limiting the effect of undesired impurities on the quality of blister copper produced, is also described.

Jan 1, 1998

By Vladyslav P. Yakubovsky, Boris I. Bondarenko, Valentin A. Noskov, Vladyslav M. Sokolov

"Each of Ukrainian producers of ferronickel, stainless steel and synthetic diamonds has the same basic problem with recycling their fine Ni-containing secondary materials. The conditions for generation of them along with the correspondent properties were investigated in details. The new approaches for their recycling have been proposed. They are based on application of some pyrometallurgical processes that are used in Ukraine. The proper equipment is also available. It has been shown that the dust from laterite calcining process of ferronickel production should be efficiently recycled by sintering. The stainless steel dust should be smelted after briquetting as a charge addition to the Ni-containing discarded batteries in the elaborated furnace. The sludge after synthetic diamonds production should be pelletized and processed by liquid cast iron with application of induction magnetodynamic forces in the specific furnace.IntroductionThe object of the investigation is recycling the Ni-containing secondary fines in a form of dust and sludge. There are several generators of the fines in Ukraine. Namely they are Pobuzhye Integrated Ferronickel Mill; Electrometallurgical Works “Dneprospetsstal” with stainless steel plant as well as Poltava Diamond Plant that produces synthetic hard materials. Their businesses are the largest in the Commonwealth of Independent States (CIS). However the status of handling with the fines is not perfect since the applied recycling technologies are low efficient. The landfilling option is often adopted for them. At the same in Ukraine there are some nontraditional pyrometallurgical recycling technologies and equipment that should be tried for application in smelting these secondary materials.Recycling the sludge of synthetic diamonds productionThe sludge of “Poltava diamond plant” from production of synthetic hard materials has a following chemical composition, %: iron oxide – 29.7; chromium oxide – 18.97; nickel – 4.27; manganese oxide – 15.2; sulphate – 3.85; natrium – 14.9. The content of moisture is 70-80%. The moisture quite quickly evaporates while keeping sludge out of doors. Sludge returns into the weak agglomerates. The sizing of the dried sludge particles presents the figures from 400 to 1000 µm. The moisture was extracted by sludge pressing. The content of the basic compounds of the moisture is, g/dm3: chromium oxide – 1.6; nickel – 0.001; manganese oxide – 0.002; lead – 0.005; sulphate – 13.6; natrium – 17.0."

Jan 1, 2008

By C. K. Gupta

Electrometallurgical processes have a definite place in the extraction technology of rare earth metals and alloys. Some of the advantages of the molten-salt electrometallurgical processes include fast electrode reaction, providing accurately controlled large amount of energy to a relatively small reactor volume, negligible over voltage, simplicity of operation, and possibility of accomplishing continuous or semicontinuoue operations. This paper provides a vivid account of the theoretical and practical aspects of electrometallurgical processes for the production and processing of some of the rare earth metals and alloys. Reference has been drawn to the work reported on electrometallurgical processes as applied to the preparation of lanthanum, cerium and misch metal from author's laboratory.

Jan 1, 1992

By K. Suseelan Nair

Magnesium alloys containing rare earths are finding increasing applications in space programmes. A number of alloys have been developed and e good data base an the mechanical properties of these alloys is available. However details on metallurgical aspects are found to be sparse in, literature. This paper, at first, briefly reviews the available data on these alloys and subsequently presents the microstructural investigations conducted on quatenary fig-4.9% Zn-1% Rare earth-0.5% Zr cast alley, using optical metallic-graphy, electron probe micro-analysis and X-ray diffraction techniques.

Jan 1, 1989

By A. A. Bustos

A model was developed to simulate the blow-by-blow operation of the converting process. From the weights, compositions and temperatures of all converter feeds the model calculates the composition and tonnage of both converter matte and slag as well as bath temperature at the end of each blow. The development of the model and its application to the converter aisle operation are described. There is good agreement between model predictions and observed results. At the present time the model is being used to investigate different converting schemes and their effect on pay metal recoveries, slag chemistry and temperature of the bath. Future work involves the use of the simulation model as a process control tool for the converting operation.

Jan 1, 1988

By J. J. Kim

In a study of buildup in a green-feed reverberatory furnace, it was determined that approximately half of the crucible area has a moderate buildup of 25 in. or less, and that the area extending 45 f t from the burner end of the furnace has only a slight buildup. The false bottom, averaging 6 in. in thickness, was found to cover the entire crucible area. The stratification of Cr2O3, A12O3, and SiO2 occurs throughout the slag layer; this phenomenon is the principal reason for the formation of the false bottom in the green-feed reverberatory furnace. The false bottom is caused primarily by the settling of FeO*(A1,Cr),03 aggregates, which are derived mainly from returned converter slag. The false bottom can be transformed to a solid permanent buildup in the furnace, particularly when the matte is completely withdrawn. From the material balance of Al2O3 and Cr2O3 around the furnace, It is estimated that the average rate of aluminum chromite accumulation is approximately 0.3 ton per day or less.

Jan 1, 1976

By B. Wasmund, K. Adham, K. O'Keefe, C. Lee

"Metal chlorides (e.g. iron and nickel) can be pyrohydrolysed at elevated temperatures to yield an HCl rich off-gas and a metal oxide product. Typically, the high energy requirement for pyrohydrolysis is provided by the combustion of a hydrocarbon fuel with air. Here, it is demonstrated that the use of oxygen-enriched combustion can result in lower fuel requirements and higher HCl concentrations. In addition, the oxygen enrichment can result in a smaller volume of off-gas and thus, smaller and less expensive process equipment. This new concept can be applied to both the spray roaster (SR) and the fluidized bed reactor (FBR). Similar to the aircombustion case, the oxygen-enriched process can use a direct contact venturi scrubber, to recover energy from the roaster off gas, but at a higher efficiency. The new process also uses an absorption tower for capturing HCl from the roaster off-gas, but generates a stronger HCl solution than is possible with pyrohydrolysis in air.BackgroundIn recent years, the metallurgical industry has become increasingly involved with developing methods for extracting metals, upgrading products or cleaning metallic products by using hydrochloric acid. These applications of chloride metallurgy often result in metal chloride solutions, which should be processed to regenerate HCl for reuse, and to recover the metal value as a product or by-product oxide [2, 3, 4].The pyrohydrolysis of metal chloride solutions has been done in two types of air roasters: spray and fluidized bed. The existing roasters burn a hydrocarbon fuel in air, to provide the required energy for evaporating the feed solution and to provide an elevated temperature for the chloride pyrohydrolysis to occur, according to the following reactions:"

Jan 1, 2011

By Hyun Kyu Shin, Byeong Deok Lee, Young Eun Lee

The reduction of Mn oxides at pre-smelting steps is an integral part of smelting processes for Mn alloys, and an understanding of its reaction mechanism is expected to contribute to the improvement of processing efficiency for Mn alloys smelting. The phase diagram shows that five Mn carbides are operative in the Mn-C system. Although they are expected to participate in the reduction of Mn oxides, no specific information is available yet to clarify their roles in presmelting carbothermic reaction of Mn oxides. Experiments with composite pellets prepared with Mn oxides and graphite powders show that Mn3O4 is reduced initially to MnO at about 1130oC and, subsequently, to Mn7C3 carbide as temperature increases further. At 1331oC, Mn7C3 carbide dissociates to Mn alloy and carbon. The degree of reducing reaction increases with increasing carbon balance in composite pellets and increasing temperatures.

Jan 1, 2014

By R. N. O'Brien, E. Peters

"It has been discovered that copper concentrates can be leached in strong (40-60%) sulfuric acid with nitric acid, or with oxygen if nitric acid is present as a catalyst. Chalcopyrite is rapidly decomposed at temperatures well below the boiling temperature of the lixiviant (-150 C.) and the resulting copper and ferric salts are precipitated as CuS04.H20 and FeH(S04)z.4H20. Other metal sulfides such as zinc, lead, nickel, etc. are also converted to sulfates that are nearly insoluble. Sulfur is partially converted to elemental and partially to sulfuric acid. Reduction products of nitric acid can be recovered from the distillate with good recovery. Conversion of as-received copper concentrates is largely complete in about 1 hour. Introduction9 molar sulfuric acid is an unusual hydrometallurgical lixiviant: it has a boiling point of about 150 C. and a low solubility for base metal sulfates. Below about 6 molar acid, the boiling point falls below 120 C. and yields much higher sulfate salt solubility, while above 12 or 13 molar acid and at higher temperature sulfuric acid becomes an oxidizing agent, yielding gaseous S02' Thus, sulfuric acid within this range of concentration is capable of acting well above the temperature of boiling water without requiring autoclave conditions, and if typical oxidative leaching conditions are applied to suspended mineral sulfide concentrates, it is possible to obtain a conversion of these sulfides into 'crystalline sulfates. Thereafter, the sulfates can be separated by filtration or by solid - bowl centrifuge and the solution can be recirculated to the reactor vessel. Meanwhile, the solid sulfates can be treated in a typical hydrometallurgical circuit, i.e., dissolved in a return stream that is essentially water, separated from each other by, for example, solvent extraction, and recovered as metals by electrowinning."

Jan 1, 1997

The resist profile simulation is carried out using the combined data obtained. The nematic liquid crystal is clear only when a long range order exists, in the whole medium. using the Jones matrix method. Director can change from point to point and is, in general, a function of space. Details of the lens structure and of the devices fabrication and performance are described. Light from conventional light source or laser is passed through a polarizer and then incident on the specimen At the nematicisotropic, transition temperature, the medium becomes isotropic and looks clear and transparent. The transition can be approached by changing the impurity concentration or, indirectly, by tuning the temperature since the pinning strengths of the random and crystal potential have in general a different temperature dependence.

Jan 1, 2006

By B. J. Elliot

The Outokumpu Oy flash smelting furnace was designed for a capacity of 69,5 mtph of concentrate. The history of developments on the flash furnace, from the original operating capacity of 55 mtph to a proven capacity of 115 mtph of concentrate, is summarised. The new feature of operation at BCL Limited is ?the use of screened lump coal reduction in the settler region of the furnace. This paper considers the effects of settler bath reduction on the furnace smelting capacity, the condition of the furnace ?lining and bath, and ,the slag losses generated from the flash furnace and ultimately to discard. By using the settler bath reduction technique the capacity of the furnace for smelting new concentrate has been increased by 15% and hearth accretion has been eliminated by direct reduction with coal, which has also allowed the generation of a substantial protective lining on the furnace walls and roofs. As a result of improved slag losses from lump coal charging the metal recoveries on the flash furnace have increased from 70% to 87% for nickel, 68% to 82% for copper, and 28% to 45% for cobalt.

Jan 1, 1983

By Zhihong Liu

Monodisperse micron size nickel oxalate particles with rhombohedron morphology were prepared from condensed Ni(OH)2 suspension by a novel gel-sol process proposed by one of the authors. Firstly, condensed nickel hydroxide gel was formed by fast adding 1 mol dm-3 NaOH solution into 0.2 mol dm-3 nickel chloride solution, and then oxalic acid solution with a concentration of 0.25 mol dm-3 was dropped into the gel drop wise through a pump equiped with a pH controller under preset pH value, and in this process, Ni(OH)2 gel was converted gradually into monodisperse nickel oxalate sol. The formation of the nickel oxalate particles was found to proceed through a dissolution-recrystallization mechanism from the nickel hydroxide gel. The product particles exhibited rhombohedron like shape with micron size long axis and sub-micron size short axis. The effects of such factors, as temperature, surfactants, et al, were evaluated experimentally on the particles sizes and morphologies.

Jan 1, 2006

Two pilot-plant investigations were conducted in which strong-base resins were compared with activated carbon for the extraction of gold cyanide from leached pulp from the Golden Jubilee Mine. The results show that gold can be recovered with carbon, but that the extraction efficiency is poor, probably because high concentrations of humic and fulvic acids are. present m the pulp. .However the extraction of gold cyamde from this material with strong-base resins JS very effo:1ent, and the overall efficiency of extraction is better with resin than with carbon, even when the concentration of resin is one-third that of carbon, and the flowrate of resin is one-third that of carbon. The results of the pilot-plant campaign reported in this paper led to the conversion of the Golden Jubilee plant from carbon-in-pulp to resin-in-pulp in February 1988.

Jan 1, 1989

Due to problems with old technologies more and more product designers have turned to liquid crystal (LC) displays, which have consequently experienced phenomenal growth. The success of liquid crystal displays has fostered continued development, to the point where full-color video displays have been realized which can rival. The details of the lens structure and of the devices fabrication and performance are described using the Jones matrix method. Director n can change from point to point and is, in general, a function of space.. The transition can be approached by changing the impurity concentration or, indirectly, by tuning the temperature since the pinning strengths of the random and crystal potential have in general a different temperature dependence. Light from the conventional light source or laser is passed through a polarizer and then incident on the specimen. The resist profile simulation is carried out using the combined data thus obtained. The nematic liquid crystal is clear only when a long range order exists, in the whole medium. At the nematic-isotropic, transition temperature, the medium becomes isotropic and looks clear and transparent.

Jan 1, 2006

By K. Sadrnezhaad

Industrial and experimental induction furnaces are used for melting various types of iron ingots, returned scraps and DRI sponge pellets to produce high purity cast-iron and steel heats. The lowest consumption of the electrical energy is determined for continuous feeding operation to be 0.3 KWH/Kg for production of cast-iron in 1.5-ton industrial furnace and 0.45 KWH/Kg for production of steel in 25-Kg experimental furnace. The optimum feeding rate for lowest energy consumption is obtained to be 12.5 grams per second for continuous feeding of DRI in 25-Kg induction furnace. Similar measurements show that the optimum size of the DRI pellets is around 8 millimeter.

Jan 1, 1988

By Christopher Solnordal

A mathematical model was developed to simulate the performance of the reaction shaft at BHP-Billiton?s Olympic Dam copper flash smelter. In order to have confidence in the predictions of the mathematical model, validation was performed by comparing and reconciling the predictions from the model with the results from a campaign of sampling and plant measurements. The model was based on the computational code CFX4.4 utilizing a combustion sub-model purpose-built by CSIRO. The combustion sub-model employed the concept of a composite particle which contained the three components of the solid charge: concentrate, flux and returned dust. Plant measurements were made and samples taken immediately below the burner and through a port halfway down the reaction shaft. Parameters measured included temperature, solid loading and SO2 concentration in the gas. Comparison of the measured and predicted values then showed that: predicted far field gas temperatures were within ±50C of measured values; predicted temperatures in the central plume were lower than measured, and, the predicted plume width was slightly smaller than measured. An optimum composite particle size of 19 m was identified for use in future modeling work at Olympic Dam.

Jan 1, 2006