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By A. J. Rigby

Current practices employing porous plugs to inject nitrogen into molten copper during primary smelting are described. Nitrogen stirring increases heat transfer to the bath, eliminates temperature stratifications, and improves efficiency during the steps of desulfurization and deoxidation. The opportunity to use porous plugs as the means to introduce reducing gases to deoxidize copper is also discussed. Previously reported laboratory results using porous plugs, which point to very high utilization efficiencies of hydrogen when used as the reducing gas, are again reviewed. Advances in the design of the porous plug, and the introduction of a system enabling external replacement of plugs is also discussed.

Jan 1, 1999

By Józef Czernecki

The Polish copper concentrates are characterised by low content of sulphur and iron. At KGHM Polska Miedz S.A. two copper production technologies are in use. The shaft furnace process is used at the Legnica Copper Smelter and the Glogów I Copper Smelter. A single-stage direct to blister Outokumpu flash smelting process is used at the- Glogów II Copper Smelter. Melting copper concentrates in the shaft furnaces is carried out in a reducing atmosphere and the product obtained is a matte. Instead, a result of melting copper concentrates by an oxidising flash process blister copper of a quality similar to that of converter copper is obtained. The annual copper production at KGHM Polska Miedz S.A. exceeds 450,000 tons. Another important metal is silver produced from slimes from copper electrolysis (about 1000 t/y). Moreover, such metals as Pb, Ni, Se, As, Au and other precious metals, including Pt and Pd, are recovered from various semiproducts. This paper presents technological flow sheet of the copper production in plants using the shaft furnaces and in another plant in which a single-state flash process is applied. Characteristics of products, methods of their utilisation, main parameters of particular technological operations, and advantages and shortcomings of the solution applied are presented. There are also discussed: the natural environment protection as well as directions of the KGHM Polska Miedz S.A. plants modernisation.

Jan 1, 1999

By Harold R. Kokal

Lisakovsky is a 3-billion ton oolitic iron ore deposit in north-central Kazakhstan operated by Orken LLP, a subsidiary of Ispat Karmet and the LNM Group. The iron oxide minerals are goethite and limonite. The gangue occurs as discrete quartz grains and an unidentified form of colloidal silica-alumina. The concentrate produced contains about 49.5 percent iron (Fe) and 0.6-0.8 percent phosphorus (P) or 10-20 times the acceptable phosphorus level. The phosphorus is intimately associated with the iron oxide and colloidal gangue, no discrete phosphorus minerals are found, and beneficiation is not possible. Therefore, to reduce the phosphorus, a hydrometallurgical process that includes roasting followed by leaching in dilute sulfuric acid has been developed. Phosphorus extraction is 70-90 percent, with only a minor loss of iron. The process has been tested in the laboratory and in a pilot plant at 50-300 kg/h. Construction of a 900,000 t/y demonstration plant is underway.

Jan 1, 2003

By Benjamin Vidales

Copper in concentrations above 0.5 weight percent in iron and steel causes hot shortness. This tendency is intensified in the presence of dissolved tin above 0.05 weight percent in the alloy. The understanding of the mechanism of removal of copper from molten iron and steel is of industrial importance. In this investigation, we present the experimental results of the removal of copper from molten iron using sulphide flux in the temperature range 1000°-1500°C. The solution thermodynamic properties of binary sulphide melts have been estimated by using the relevant phase diagrams and the behaviour of copper sulphide in these melts is discussed. The kinetics and thermodynamics of the removal reaction are also explained and, the experimental results are also reported showing the equilibrium distribution of copper and sulphur in molten iron.

Jan 1, 1995

By Kent D. Peaslee, Lifeng Zhang, Edith Martinez, Yufeng Wang

The current study investigated the multiphase fluid flow, heat transfer, solidification of the steel, and the motion and entrapment of inclusions during the centrifugal casting process using FLUENT software. User-defined functions (UDFs) were developed to add velocity with a value related to the rotation speed and radial distance to the solidified steel, to exert a centrifugal force to the motion of inclusions, and to add the entrapment condition of inclusions at the solidifying shell and export the entrapment locations of the inclusion. The calculation shows that there are two peaks of inclusions along the thickness of the produced tube: one at close to outer surface and another one close to the inner surface of the tube. With a larger rotation speed, inclusions tend to be entrapped more towards the inner surface. The calculation agrees well with the industrial measurements.

Jan 1, 2012

By Shigeo Asai

History of EPM is described and several functions utilized in EPM are reviewed. Main activities of EPM are summarized with the view on mass production and applications of high magnetic field related to nano-technology. Future trends and prospects of EPM are discussed.

Jan 1, 2006

By S. D. Prosser

The earliest record of slag in the world was the discovery of the remains of a copper blast furnace in Southern Israel, which has been carbon dated at 3500BC, nearly 6,000 years ago. Slag in Australia is a much more recent phenonenum with the first iron blast furnace commencing operations in 1848. The early days of metal smelting in Australia were marked with many company failures due to a variety of reasons. This paper traces the progress of metal and slag production from those early days up to the present times

Jan 1, 1994

By John K. Wright

The segregation process involves heating oxide-type ores with a halide salt in the presence of a solid reductant. By a complex series of cyclic vapour-phase reactions, the desired metal is extracted from its original position in the ore and segregated to the vicinity of the reductant. In this form it is then amenable to concentration by physical methods. In this work the segregation behaviour or eight different nickel laterite ores has been examined using a laboratory rotary kiln. It was found that the silicate (serpentine) ores responded better to the segregation conditions used than did the limonitic ores. An examination of the segregated metal particles showed that they consisted of ferro-nickel. The concentration of nickel in the metallics was sensitive to the ore types and the segregation roasting conditions.

Jan 1, 1994

By D. N. Collins

A sampling program was conducted in which both spoon and isokinetic sampling techniques were used to collect samples from the reaction shaft. The samples were then characterised by chemical, XRD and mineralogical analysis. Further information was acquired by measuring the oxygen potential and temperature at the bottom of the shaft using disposable probes. Comparison of the results of the two sampling methods showed that the spoon samples were devoid of material less than 25 m. Sulfur analyses on the samples provided information on the extent of reaction, plume shape and recirculation patterns. Disposable probe measurements showed the measurable particle temperatures ranged from 1150 to 1700 °C and that the material falling into the bath had a normalised oxygen potential similar to the slag. These latter measurements combined with the sulphur elimination and mineralogical analyses provided further information on the extent of reaction and enabled the reaction sequence to be ascertained.

Jan 1, 1999

By L. -C. Lai

A series of LaNi5-based alloys, with partial substitution of Ni by Al, Co, or V, were prepared The gas-phase hydrogen absorption kinetics and pressure-composition-temperature curves were measured The activation became easier and the plateau pressure was reduced as Ni was partially substituted by Al Substitution with Co reduced the hysteresis as well as the hydrogenation capacity, but enhanced the absorption kinetics Vanadium is often considered as a hydride former, but when it was added to LaNi5, it was found that V occupied the B site. A small amount of substitution of Ni with V led to a higher hydrogenation capacity and faster activation rate Based on these properties, an alloys LaNia 25CO0.5V0.1Al0. 15 was fabricated as an electrode. Compared with LaNi4.85Al0.15, it was found to exhibit faster activation, higher discharge capacity, and longer cycle life. The variation of the hydrogenation characteristics is discussed based on the physical and chemical properties of the alloying elements.

Jan 1, 1997

By Joel K. Witt

San Manuel Oxide operations of BHP Copper, located in Southeastern Arizona, operates a leach-solvent extraction/electrowinning (SXEW) facility that produces high quality cathode copper from low-grade oxide ores. Permanent heap leaching and in-situ leaching methods accomplish the dissolution of copper from the oxide ores. Open pit mining and heap leach construction took place from 1985 to 1995. Run-of-mine oxide ore from the pit was hauled to the heap dumps and leached by the soaking cure and continuous irrigation method. Solution application to the heaps still continues and acid soluble copper recovery has reached 86%. This paper presents and discusses the current operating practices and innovations applied to the leach facilities to maximize copper recovery from the heap leached residue. Factors such as irrigation methods, solution chemistry, sideslope treatment, post curing, lixiviant acid strength, and "rice paddies" irrigation, will be discussed. Heap leach solution control and sampling methodologies will be also presented.

Jan 1, 1999

By H. Tan

?Preg-robbing? is the active adsorption of gold from cyanide solution by the ore components. The role of carbonaceous coatings on chalcopyrite surfaces in the preg-robbing of chalcopyrite has been investigated by using pure chalcopyrite and a copper concentrate. Activated carbon and graphite were chosen as representative carbonaceous contaminants. It was found that the carbonaceous coatings enhanced the preg-robbing of chalcopyrite. Activated carbon coating increased gold adsorption onto chalcopyrite to a lager extent, in comparison with graphite coating. In the preg-robbing of the copper concentrate, gold adsorption was increased to larger extent at finer particle sizes and at higher contents of activated carbon or graphite. The preg-robbing of chalcopyrite was reduced or eliminated, depending on the concentrations of free cyanide. However, the gold adsorption on the carbon and graphite coated chalcopyrite could not be avoided even at higher cyanide concentrations, and this adsorption was solely attributed to the carbonaceous coatings. Zeta potential studies indicated that the carbonaceous coatings reduced the negativity of the chalcopyrite surface charge. As shown by SEM analysis, gold not only accumulated at the edges and defect sites, but was also spotted on the smooth surfaces of chalcopyrite with carbon or graphite present. XPS results revealed that gold was strongly reduced on chalcopyrite surfaces, with the sulfide ions of the chalcopyrite being oxidized to elemental sulfur. Diagnostic elution indicated three mechanisms contributing to gold take-up by chalcopyrite, i.e. gold reduction, physical adsorption and chemical adsorption.

Jan 1, 2003

By C. Lupi

Zinc chloride electrowinning presents difficulties in obtaining smooth, compact and dendrite free deposits with a high current efficiency due to the presence of undesirable metal ions. However, it is hard to define a level of impurities tolerable in zinc deposition, and despite a lot of research in this field, the reaction mechanisms of the undesired metal ions are still not clearly understood. In this study, the influence of Fe, Cd, Co, Ni and Cu additions were investigated, as well as their synergic effect on the zinc electrodeposition process from chloride electrolytes and on the obtained deposit morphology. The tests were all performed in presence of TBACl which reduces the harmful effect of such impurities on the zinc reduction.

Jan 1, 2003

By L. Béjar-Gómez

The aim of this research work is to study and characterize precipitates in structural microalloyed steel by transmission electron microscopy and analysis by high resolution (HRTEM). Microalloyed steel with titanium was produced by casting in an electrical induction oven of 25 Kg. capacity. Carbon content in steel was less than 0.1 % and titanium content of 0.04%. Steel was processed thermomechanically; reheated to 1250ºC and hot rolled on a laboratory mill to a 13.0 mm thick plate with a finish rolling temperature of 900ºC and thickness reduction of 80%. Analysis by High Resolution Transmission Electron Microscopy (HRTEM) identified precipitates in the steel; type and morphology. Energy Dispersive Spectroscopy (EDS) analysis was applied to obtain the chemical composition of precipitates and the matrix. STEM-EDS analysis was also applied to obtain the element profile of precipitates. The results showed the presence of carbonitride precipitates of titanium, Ti (CN), with a circular morphology and size of 10 nm and less.

Jan 1, 2006

By John Sakala, Jeyapandian Sasikumar, Sydney Kwalela

The Isasmelt Furnace was commissioned in September 2006 with a concentrates treatment capacity of 850,000 tonnes per annum. However, the converter section became a bottleneck to the high throughput. Over 25% of the Isasmelt Furnace down time was attributed to lack of converter space. Factors that affected converter operations were low tuyere line campaign life (an average of 150 blows), high reverts generation, low conversion rates, and high converter cycle time. As a result of efforts carried out to improve converter operation, the average campaign life has increased to over 250 blows and reverts generation has been reduced from 22% of concentrate treated to 15%. Blister copper conversion rate has increased from 15 tonnes per hour to 19 tonnes per hour and blowing time per cycle has been reduced from 5.7 hours to 4.7 hours.

Jan 1, 2012

By C. K. Gupta

The paper reports on the experimental work and results obtained in processing a xenotime concentrate. The rare earth resource concentrate has been treated by three different methods namely, hydrothermal leaching, alkali roasting and alkali pugging or baking. The recovery in hydrothermal leaching with caustic soda at 150-160°C has been 89%. En comparison, processes involving alkali roastings with soda ash at 850°C and with caustic soda at 500°C, and alkali pugging or baking with caustic soda at 200°C have given recovery values close to 100%

Jan 1, 1992

By Brian Lightfoot

Ausmelt Technology uses a furnace/slag/lance system in a way analogous to the way a chemical engineer would use a mixed reactor. The technology is sufficiently versatile to treat materials under a very wide range of temperature and chemical conditions. At one extreme the system has been operated at temperatures high enough and oxygen potentials low enough to make iron. At the other extreme it has been operated of temperatures as low as 800°C and oxygen potentials high enough to cupel lead from silver. This versatility permits the treatment of a great variety of wastes including asbestos, mixed organic\heavy metal wastes, incinerator ash smelter residues, waste water treatment sludges, organochlorine compounds and many others.

Jan 1, 1994

By M. Hashiuchi

In 1972, the tankhouse of the Tamano Smelter adopted a high current density electrolysis operation applying the PRC (Periodic Reverse Current) method. In 1994, the phase four production expansion project, which incorporated significant re-structuring of the organization, was completed and we have achieved an annual production capacity of 191,000 tons. The target of this project, the production capacity, was increased by 1'8% and labor productivity by 25%. After the expansion, some improvements in the starting sheet section and the verticality of the electrodes were carried out, and the efficiency of the operation was greatly enhanced, including the improvement of the quality of the electrolytic copper.

Jan 1, 1999

By Jung-Ah Kim

Precipitated Calcium Carbonate (PCC) is obtained through calcination, hydration, and carbonation. Thus, the change in each process condition determines the particle size or morphology of PCC. To date, studies on precipitated calcium carbonate have mainly focused on process manufacturing PCC, aimed matter. Still, few studies on calcination or hydration have been conducted. Therefore, this study sought to investigate the effect of hydration condition on the synthesis characteristics of aragonite PCC. Results showed that the particle size of calcium hydroxide changed based on the variation of the initial hydration temperature. In particular, higher initial temperature resulted in the larger particle size of calcium hydroxide used in synthesis. The particle size and yield of aragonite also increased when calcium hydroxide made at high temperature was used. The water/solid ratio or total amount at the hydration time had no effect on the manufacturing process of aragonite, however.

Jan 1, 2006

By Gregor Mori

Niobium electrolysis has been performed in a NaCl-KCl-NaF-NbCls electrolyte. By means of electrolytic .refining the average valency of the niobium ions was determined as well as the crystallization behaviour. In electrowinning runs the influence of the main parameters such as temperature, RF (mole ratio F/Nb), chemical prereduction, niobium content of the melt and current density has been determined with respect to low specific energy consumption and high purity of the deposit.

Jan 1, 1995