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By Hong Yong Sohn

Keywords: Barium sulfate, Barium sulfide, Environment, Kinetics, Pollutants, Sulfur dioxide conversion, Thermodynamics Nonferrous smelters and coal gasification processes generate sulfur dioxide streams, most of which are treated to produce sulfuric acid with the accompanying problems of market shortage and transportation difficulties. While the conversion of sulfur dioxide to elemental sulfur has many environmental advantages, no processes exist that are environmentally acceptable and economically viable. A method for converting sulfur dioxide to elemental sulfur by a cyclic process involving calcium or barium sulfide and calcium or barium sulfate without generating solid wastes has been developed. In this process, the sulfate, as the starting raw material, is reduced by a suitable reducing agent such as hydrogen to produce the sulfide, which is used to reduce sulfur dioxide producing elemental sulfur vapor and regenerating the sulfate. The latter is then reduced to reproduce the sulfide. This paper describes work on the BaS/BaSO4 system. Thermodynamic analysis and experimental results indicated that the BaS-SO2 reaction produces mainly sulfur vapor and solid barium sulfate and that the gaseous product from the BaSO4-H2 reaction is mainly water vapor. The rates of the two reactions are reasonably rapid in the temperature range 700-1050°C.

Jan 1, 2005

By Pinai Mungsantisuk

Keywords: Pd-Ni alloys, Pd-Fe alloys, Pd-Co alloys, Magnetostriction, Magnetic Properties The presence of congruent melting minima, the occurrence of ferromagnetic transition over a large composition range, and FCC type crystal structure make Pd-Ni, Pd-Co, and Pd-Fe based systems attractive candidates in our search for materials with no rare-earths, large low-field magnetostriction, and good mechanical properties. The presence of paramagnetic-ferromagnetic transition over a broad range of composition also provides opportunity for fundamental studies. In this work, we have examined the magnetic and magnetostrictive behavior of Pd-Ni, Pd-Co, and Pd-Fe alloys over the entire composition range. Alloy sample rods were prepared by arc melting and casting. X-ray diffractometer was used to obtain lattice parameter data. Magnetostriction was measured along the rod axis using strain gages. Magnetic properties were measured using a vibrating sample magnetometer.

Jan 1, 2005

By Purushottam Kumar

Keywords: Magnetostriction, magnetic properties, Pd(Fe,Co,Ni) single crystals Fe-Pd, Co-Pd and Ni-Pd alloy systems show appreciable magnetostrictive strains that are of interest for sensor applications. These systems exhibit congruent melting minima. In this work the magnetic and magnetostrictive behavior of congruent melting Fe-Pd, Co-Pd, and Ni-Pd compositions have been examined. The alloys examined include Fe-54.9 at.-% Pd, Ni-45.4 at.-% Pd, and Co-45 at.-% Pd. The paper describes the growth of bulk single crystals of these alloys using Czochralski technique. X-ray diffractometer was used to obtain rocking curves that were used to determine the [001] crystal direction. Magnetostriction in [001] direction was measured using strain gages. Magnetic properties were measured using a vibrating sample magnetometer. Ni-Pd showed the highest magnetostriction values among the congruent melting compositions. Magnetic and magnetostrictive behaviors of these alloy single crystals are presented.

Jan 1, 2005

By Juan Patricio Ibáñez

Separation of arsenic and copper from Cu-As-H2S04 electrolytes by electrodialysis has been investigated at room temperature. The effects of current density and pH were studied. An arsenic-free copper solution was obtained for all the tested conditions. The transport efficiency for copper ions was found to be higher than 98% after 3 hours' test. Transport of arsenic and copper through the ion exchange membranes was increased by increasing pH and current density. Solution pH was found to be a key parameter for the separation process, since it controls the speciation of the ions to be transported and the formation of unwanted precipitates which reduce the global efficiency of the electrodialysis process. The main conclusion is that electrodialysis is a promising technique to be used in separating and/or concentrating ions of interest in copper electrometallurgy.

Jan 1, 2003

By Han-Tao Hu

Keywords: RH refining process, flow of molten steel, two-phase flow, gas holdup, circulation rate, mathematical modeling A three-dimensional mathematical model for the flow of the molten steel in the whole degasser during the RH refining process has been proposed and developed with considering the physical characteristics of the process, particularly the behaviors of gas-liquid two-phase flow in the up-snorkel and the momentum exchange between the two phases. The fluid flow fields and the gas holdups of liquid phases and others respectively in a 90 t RH degasser and its water model unit with a 1/5 linear scale have been computed using this model. The results showed that the flow pattern of molten steel in the whole RH degasser could be well modeled by the model. The liquid can be fully mixed during the refining process except the area close to the free surface of liquid and zone between the two snorkels in the ladle, but there is a boundary layer between the descending liquid stream from the down-snorkel and its surrounding liquid, which is a typical liquid-liquid two phase flow, and the molten steel in the ladle is not in a perfect mixing state. The lifting gas blown is rising mostly near the up-snorkel wall, which is more obvious under the conditions of a practical RH degasser, and the flow pattern of the bubbles and liquid in the up-snorkel is closer to an annular flow. The calculated circulation rates for the model unit at different lifting gas rates are in good agreement with the determined values.

Jan 1, 2005

By Faustino G. Prado

In the, quest for an economical and environmentally friendly reclamation of metallurgical dusts generated during pyrometallurgical operations, our goal has been the separation and recovery of most of the components, as well as the complete recycle of all the reagents. Effluents have been avoided, within acceptable economic parameters. This presentation, which can be applied to a large spectrum of dusts and other residual-materials-, has focused on the dusts generated by the operation of Secondary Copper Smelters. Those dusts show a wide range of components, including zinc, lead-, copper, cadmium, tin, chlorine and-alkalies. Our present work deals with the use of ammonium salts in the separation and recovery of-the above mentioned elements in a marketable form. Most of the chemistry and techniques involved have teen already confirmed in commercial scale operations. Others have gone through pilot scale tests or bench scale tests. The recycle of reagents has also been- confirmed at the same operating levels. A preliminary evaluation indicates that the chosen route, in addition to a viable economy, offers a complete and safe reclamation within the most strict environmental regulations.

Jan 1, 1995

By A. E. M. Warner

At the Copper Cliff Smelter, Inco Limited has extensive experience in converting primary smelting mattes over a broad range of nickel/copper ratios and compositions. In the past 35 years, technology developments at Inco have reduced the number of Peirce-Smith converters in Nickel/ Bulk (nickel-copper matte) service from 13 to the current 5. This paper will discuss: ? The performance and life of ?stretch? 13.7m shells versus conventional 10.7m converters. ? Process control and information system development from the early 1980?s to view converter aisle status on a continuous basis to the recent central control of the stretch shells. ? Nitrogen cooling of finishing matte from plant testing to implementation in the early 1990?s to replace the dedicated cooling converters. ? The impact on converting of changing the smelter flowsheet in the early 1990?s. ? A current program to develop a converting strategy for the future to address environmental issues and profitability.

Jan 1, 2005

By Susumu Okabe

Top blowing lances are employed by the Mitsubishi Continuous Copper Converter for the continuous supply Of reaction gases into moken bath. In order to minimize the refractory wear caused by the interaction between the furnace lining and the melt splash. optimum furnace design and blowing condition are? required. An empirical equation obtained by the physical model study enables the estimation of the splashing rate on a vel1ical plane at a certain distance from the lance.

Jan 1, 1996

By Nicolas Reynier

The separation of radionuclide during rare earth element (REE) production is an important requirement for developing the Canadian REE mining industry. Separation of actinides from REE is often a large concern in the rare earth industry because of the need to manage the radioactive nuclides. A patented process developed for actinides extraction from radioactive wastes was applied to REE ore. Objectives were to optimize the process for REE leaching from ore, and separate radioactive impurities from sulphuric and nitric liquor by ion exchange (IX). Ore leaching was optimized using a surface response plan to ensure statistical significance. In optimized conditions, solubilization yields ranged from 90–95% for Th, 60–75% for U, 48–55% for LREE, and 59–75% for HREE in sulphuric and nitric media. Both media were compared for radionuclide removal from rich REE-bearing mineral liquor by IX. Actinides separation ranged from 92–97% for Th and 69–96% for U in sulphuric and nitric media.

By Fumio Hashiuchi, Yushiro Hirai, Masatoshi Maeda, Toshihiro Nagata

"Increase in the copper smelting capacity at Saganoseki Smelter & Refinery was attained through various improvements in the PSconverters and the flash furnace. Two of the major innovations in the converting process were: a new operational technology which avoids increase in the copper content in the converter slag even when higher copper grade matte (65%) are treated in the slag making stage and a technology which shortens the operational interruption time which is caused by coolant charging. The latter was realized by introducing a new automated coolant charging system with which it was made possible to charge the coolant without stopping the blowing into the converter. These improvements brought about a remarkable increase in · the production capacity per converter and an annual production of 450,000 tons of copper without adding new furnaces was made possible. In addition, good results have been obtained of the tests with modified tuyeres to further increase the production.IntroductionIn a bid to renovate its Saganoseki Smelter & Refinery and to establish a leading production unit in terms of global competitiveness, Nippon Mining & Metals undertook major restructuring efforts since 1994. One of its themes was the shift from· a two-flash furnaces operation to a single-flash furnace operation. The shift was successfully completed in 1996 while maintaining the production at the same level (330,000 tons per annum of copper). Then, the productivity was enhanced to 450,000 mtpy without adding new furnaces through technological and operational improvements. It is now planned to increase the smelting capacity further to 470,000 mtpy this year.Some technological and operational improvements in the matte converting process and the new plan resulted from the tests with modified tuyeres are presented in this paper."

Jan 1, 2000

By Emmanuel N. Zevgolis Ismene-Polyxeni Kostika

Keywords: reduction, kinetics, laterites, rotary kiln, dust In this work, the reduction kinetics of dust from nickeliferous Greek laterites is investigated. The dust is a by-product from laterite treatment in rotary kilns and it comes from washing towers, electrostatic filters and polycyclones. Laboratory made pellets from this dust were also examined. Reducibility was studied in the temperature range of 700°C to 850°C in a laboratory tube furnace. Kinetic analysis of the results showed that at lower temperature values the mixed kinetic model verifies the experimental results of dust and pellet samples. At higher temperatures (800° and 850°C) diffusion becomes the rate controlling mechanism. The calculated activation energy values verify also the above mentioned results.

Jan 1, 2005

By Zhan Jing

Keywords: thermodynamic, Ni-Co alloy powders, composition, fibrous The mathematics model of Ni(II)-Co(II)-C2O42?-NH3?H2O-H2O of thermodynamic equilibrium system has been developed theoretically according to the law of conservation of mass and the law of simultaneous equilibrium, and the logarithm concentration-pH (log[Me2+]T-pH) diagrams of this system have been made. The effect of ligand and pH value was studied. Two issues in coprecipitation route to synthesize fibrous nickel-cobalt alloy precursor powder, com-position and morphology which are a first priority, are addressed based on thermodynamic analysis and experiments. The results show that suitable pH value range of coprecipitation of nickel ions and cobalt ions in theory can be obtained to maintain fibrous, excellent compositonal homogeneity and stoichiometry in coprecipitation products. Experimental demonstration is also carried out.

Jan 1, 2005

By Dan A. Mackie

Continuous leaching of precious metals ores in a vat is possible using a jigging technique. This patented method promises to be competitive with heap leaching, particularly in northern climates, difficult terrain, high precipiptation regions, and environmentally sensitive areas. The paper discusses test work to date, plans for pilot plant testing and basic economics

Jan 1, 1990

By A. Galvan

High rate compressible media filter (CMF) tests produced exceptional total suspended solids (TSS) removal at hydraulic loading rates ranging from 97.8 to 122.2 m/h. The compressible media is manufactured from a robust resin fiber that can withstand low pH and temperatures up to 149 °C. The media porosity can be varied by applying compression onto the media. At 40% compression, the CMF can remove particles greater than 4 μ. Three synthetic test-samples were generated by Hazen Research Inc., (Golden, Colorado) to simulate the copper Pregnant Leach Solution (PLS), Raffinate and Electrolyte solutions used for the testwork conducted at their facility. The preliminary results showed that the CMF was very effective in removing TSS without the use of chemical conditioning from the above test-solutions with efficiencies of 98%, 97%, and 96%, respectively. Given the remarkably high hydraulic loading rates, the industrial equipment footprint would be minimized appreciably over conventional clarification and alternative filtration systems.

By J. N. Kondo, M. Hara, T. Smida, N. Ooto, K. Domen

"A porous material composed of two-dimensional anionic sheets of a layered perovskite, KSrNb30 10, was studied as photocatalyst for the production of Hz in the presence of alcohol sacrificial donors. Colloidal single and multi-layered HSr2Nb30 10 sheets were formed by intercalating ietra(n-buthylammonium) cations into the interlayeres of H+-exchanged KSr2Nb30 10 (HSr2Nb30 10), and addition of HN03 solution to the colloidal suspension precipitated the porous materials in which HSrNb30 10 sh~ets rand~mly stuck together. Original HSr2Nb30 10 before exfoliation had a BET surface area of 1 m2 g-1, whereas the surface area of a porous material prepared under optimal conditions exceeded 100 m2 g-1. The porous HSr2Nb30 10 had considerably higher photocatalytic'activitie8 for oxidation of 1-propanol and 1-buthanol than HSr2Nb39io, indicating that in the porous materials many niobate sheets are available for decomposition of these large alcohols.IntroductionQuite a research effort has gone into the design and study of porous materials. Such materials with large surface areas would have applications in highly efficient adsorbents or catalytic reactions.We have been studying photocatalytic reaction by cation-exchangeable layered metal oxides, where alkali metal cations are intercalated into the interlayers of inorganic sheets.[1,2] There are several advantages to using layered compounds rather than bulk powders for photocatalysis. Layered compound is rich in variety, in addition, modifications of them are easily performed by exchanging alkali metal cations in the inter layers for H + or other metal cations. The most important advantage is that some layered compounds have considerably high photocatalytic activities than bulk catalysts because the electrons and holes generated in each thin inorganic sheet readily reach interlayer spaces as reaction sites at the illterlayer spaces. It should be very important for further improvements· of layered photocatalysts to utilize two-dimensional inorganic sheets effectively."

Jan 1, 2000

By Junji Shibata

It is important to recover and reuse the metal values contained in various industrial wastes in a viewpoint of environmental preservation. Most of industrial products are made through the processes to separate impurities in raw materials, solid and liquid wastes being necessarily discharged as industrial wastes. Chemical methods such as solvent extraction, ion exchange and membrane, and physical methods such as heavy media separation, magnetic separation and electrostatic separation are considered as the methods for separation and recovery of the metal values from the wastes. In this paper, some examples of the application of solvent extraction to the treatment of wastes are introduced. The treatment of solid wastes such as Ni-Co alloy scrap, Sm-Co alloy scrap, fly ash and flue dust, and liquid wastes such as plating solution, the rinse water, etching solution and pickling solution are accomplished using solvent extraction technique.

Jan 1, 1996

By Godwin Beene

During recent years, copper and acid production from Nkana Smelter has formed a significant proportion of ZCCM's total output, but a number of problems affecting the smelter over the last decade have only been recently overcome. This paper discusses recent developments in the smelting practice, highlighting some of the operational problems experienced and associated solutions. The smelter performance over the decade is discussed and the innovations in the smelting technology employed to sustain production in the wake of limited re-capitalization are dealt with in detail.

Jan 1, 1999

By R. W. Smith

The flotation response and electrokinetic behavior of Chlorella vulgaris and Chlamydomonas sp . when using dodecylamine hydrochloride as collector were studied in the absence and presence of Pb(I1). Also, an electron microscopy study was made of the algae after Pb accumulation. The flotation behavior of the organisms after Pb accumulation appears at least partially related to the location of the abstracted Pb onto or into the organisms.

Jan 1, 1991

By Robert R. Grinstead

Two new ion exchange resins have been developed, which selectively absorb copper and nickel in preference to ferric iron from dilute sulfuric acid solutions of pH 1-3. The first absorbs copper and not nickel and can be readily eluted with 1-2N sulfuric acid. This resin is well adapted to the processing of copper leach liquors, including relatively low grade liquors obtained from dump leaching. The second resin absorbs nickel as well as copper in the same pH region, but only the nickel is eluted with 1-2N sulfuric acid. Elution of the copper requires much stronger (ca. ION) acid, altho both species are readily eluted with dilute (ca. lN) ammonium hydroxide. This resin, which should be useful in processing of certain types of copper-bearing solutions, may also be suitable for treating acidic nickel leach solutions of laterites and other non-sulfide ores.

Jan 1, 1976

By Zhongning Shi, Ramana G. Reddy, Min Li, Zhaowen Wang

Electrodeposition of cobalt from cobalt tetrafluoroborate (Co(BF4)2) was investigated using 1- butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) ionic liquid. The experiments were conducted at 353 K. Chronoamperometry experiments confirm that the electrodeposition of cobalt on tungsten electrode proceeds via three-dimensional instantaneous nucleation with diffusion-controlled growth process. The average diffusion coefficient of Co(II) was found to be 7.5 × 10-8 cm2s-1 at 353 K, which is in good agreement with the estimated value from cyclic voltammetry. The electrochemical deposit was characterized using SEM-EDS and XRD methods. The SEM image shows formation of a dense and compact deposit at - 0.75 V. The EDS and XRD analysis confirm that the obtained deposit is pure cobalt metal.

Jan 1, 2015