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By C. J. Newman

Prior to 1995, the smelting process at the Kennecott Utah Copper Corporation (KUCC) smelter consisted of Noranda reactors and Pierce-Smith converters. In the consideration of expansion opportunities, the existing process did not lend itself to a program geared towards processing the total output of KUCC mining and milling operations. During 1989 and 1990, a number of smelting options were evaluated. The final selection was the Outokumpu flash smelting process, coupled with the new Kennecott-Outokumpu flash converting technology. Facilities were designed and installed to process 1:0 million tonnes per year of copper concentrate, with the ability to expand to 1.2 million tonnes per year. Following the shutdown of the smelter facility utilizing the Noranda technology in May 1995, the flash smelting, furnace commenced operation in June with the flash converting furnace startup following a few weeks later. The smelter has achieved design production targets and environmental goals. Current operating rates are at or above design rates for concentrate and matte processing. Emissions are lower than the permit levels and equate to less than 3.5 kg of SO2 per tonne of copper. This paper outlines the design, construction, startup and the first two years of operation of the modernized KUCC smelter.

Jan 1, 1998

By Axel Hoppe

Although Tantalum is not usually regarded as a precious metal, its pricing structure is very similar to that of Silver. Different from precious metals, Tantalum has only industrial applications and its use is about 1000 metric tons per year. The intrinsic value of Tantalum already in .the past was a driving force for its recycling. Based on these facts the Tantalum industry world-wide is approaching the closed-loop concept of its recycling. A detailed material flow of Tantalum processing as well as recovery of residues and used products will be discussed.

Jan 1, 1995

By Michael J. Marinigh

"Increased safety requirements, higher operational costs, greater environmental restrictions, and new competitive processing techniques are the challenges smelter operators must confront in order to remain economically viable.In converting furnaces which have tuyères such as the Noranda Reactor and the Teniente, Peirce- Smith and Hoboken converters, efficient tuyère line management is critical to optimizing blowing rates, increasing refractory life, and improving safety.This paper will describe recent improvements made to equipment used for tuyère punching, tuyère silencing, tuyère pyrometry and refractory drilling of tuyères and how the proper application of the equipment can lead to operational and safety improvements."

Jan 1, 2009

By Michael Altepeter

Big River Zinc Corporation, located in Sauget, Illinois, operates a neutral leach residue circuit. The residue produced in the circuit is sold to lead smelters for subsequent recovery of valuable metals. A research program was initiated several years ago to find a means of treating the residue at Big River Zinc to recover the valuable metals. The Ausmelt submerged lance reactor was selected as the best alternative for the first step of the process. Pilot scale tests were conducted at Ausmelt's facilities in Melbourne, Australia. Separations were excellent. 99%+ of the Zn, Pb, Cd, and Ag contained in the residue reported to the oxide fume. 99%+ of the SiO2,, Fe, Mg, and Ca in the residue reported to the slag which passed the EPA TCLP test. Subsequent leaching of the oxide fumes and purification of the leach solutions using conventional procedures produced solUtions suitable for zinc electrowinning and an upgraded lead sulfate cake for sale.

Jan 1, 1992

By F. H. A. Abdalla

A process is described for the recovery of valuable nonferrous metals from steelmaking dust by suiphatizing roasting using ammonium sulphate. Maximum recoveries of soluble metal sulphates achieved at optimum conditions were> 99.0 %. Selective metal separation of the soluble sulphates in the leached liquors were performed either by controlling the roasting temperature or by adjustment the pH values of the leached liquor ranging from 3.6-6.2. Either pure zinc oxide orland tin oxide could be obtained at optimum conditions, and the products were evaluated chemically and by X-ray analyses. The residues rich in iron oxide can be removed and recycled. The mechanism of sulphatizing roasting process was considered. A general flow-sheet for the overall process of treatment the steel making dust to recover its valuable nonferrous metals was suggested, which ca be applied for other nonferrous bearing materials.

Jan 1, 1996

By D. F. Suarez

Spontaneous nodulation leading to growth of well developed glossy spheroids (generally hemispheres) of up to 0.06 cm width in 120 min has been observed during copper electrodeposition with certain levels of glue, thiourea and C1-. Thiourea alone can produce spontaneous nodulation but addition of glue and/or Cl- is required for rapid and sustained growth. In most cases once the glossy nodules develop they consume the majority of the copper deposited; thus, the specific current densities (and hence copper electrodeposition rates) on the glossy nodules are about an order of magnitude or, more greater than on the adjacent planar surfaces. The texture of the adjaoent planar surfaces is not glossy in appearance but is well faceted showing the usual deposition grain structure for such additives. Cathode potentials when spontaneous nodulation occurs are about TOO my more negative than with usual copper electroplating. This fact associated with evidence of extremely high levels of cathode surface passivation based on cyclic voltammograms indicates that the conditions which lead to spontaneous nodulation result from a very tightly adsorbed additive surface film. This film breaks down in specific points initiating the glossy nodules which then grow at extremely rapid rates. Current density is also important in spontaneous nodulation. At equal deposition times a current density of 21.5 mA/cm produced much larger glossy nodules than at 48 mA/cm2. The surface concentration of the glossy nodules was much greater in the latter case, however. The role of current density is still not well understood. The role of it as well as the relative roles of the three additives, thiourea, glue and Cl- in spontaneous nodulation is presented. Preliminary results and some possible correlations of these to help explain spontaneous nodulation are presented. It is believed that tankhouse upsets where cathode nodulation occurs may be related to this phenomenon.

Jan 1, 1987

By Ayşe Ece Yıldızçelik, Mehmet Buğdaycı, Onuralp Yücel

ZrB2 and TiB2 are significant metal borides. They are being used in various industrial areas from space technology to nuclear industry owing to their physical properties such as high melting point, high thermal/electrical conductivity and low density. Present study was conducted in two main stages: self-propagating high-temperature synthesis (SHS) reactions and leaching. ZrO2, TiO2, B2O3 were used as starting material and Mg was used as a reductant to produce ZrB2-TiB2 powders via SHS. Therefore, it was aimed to determine production parameters, leaching conditions and comprehensive examination of final product features. The samples were characterized by using chemical analysis (AAS), XRD, XRF and SEM/EDS techniques.

Jan 1, 2015

By J. R. Goode

There are at least a dozen methods of selectively removing cerium from a mixture of the rare earth elements (REE) including separation techniques based on the oxidation of cerium to the quadrivalent state. Several of the oxidation processes have been operated on a commercial scale, others have been tested and in some cases are part of proposed flowsheets. In this paper, we describe and compare the various methods. We also present preliminary estimates of the costs of early Ce removal and discuss recovery and purity aspects of the options.

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

By L. R. Verney

About 75% of the market economy countries's supply of cobalt is produced in Central Africa by Zafre and Zambia. Zafre alone accounts for more than 55% and has the resources and capacity to increase output significantly at any time so its dominant position is unlikely to be challenged in the foreseeable future. Other producers from domestic resources are Canada, Australia and South Africa; and Cuba, probably the most important producer outside of the Market Economy countries. Belgium, Norway, France, Japan and Finland produce cobalt from imported materials. While there are "cobalt ores", inMorocco, USA, Canada and the USSR, the mineralisation is complex and cobalt extraction is costly. In ZaPre and Zambia cobalt is a by-product of copper; in Canada, Australia, France, and Cuba it is a by-product of nickel; and in South Africa it is a by-product from the production of Platinum Group Metals. Thus the levels of cobalt production are inevitably related to the production of other primary metals. While some cobalt is produced by predominantly pyrometallurgical methods most of the world's cobalt is produced hydrometallurgically. The existence of large hydro-electric power plants and the mineralogy of the copper and cobalt concentrates encouraged research and development in Zafre of the recovery of copper and cobalt by electrowinning from sulfate solutions; much pioneering work was carried out, which lead to construction of the two largest copperlcobalt hydrometallurgical plants in the world, at Shituru and Luilu. Similar systems were adopted in Zambia. In Canada high pressure hydrometallurgical processes based on the sulfate system were developed and adopted in Australia, the Philippines, Finland and South Africa. Meanwhile developments in chloride hydrometallurgical extraction of nickel and cobalt lead to its use in the extraction of cobalt in Norway, France and Japan.

Jan 1, 1988

By H. K. Fouad, L. A. Guirguis

The starting mill strip solution· for this study· is an ammonium uranyl tricarbonate solution of pH 8.2 containing 20g uranium/liter, after a DEPA/TOPO extraction process from sulfuric acid leaching liquor. To the first portion of the concentrated acidified strip solution, hydrofuoric acid is added at 95°C in reduced condition to obtain uranium tetrafluoride. The second portion of the uranyl carbonate strip is subjected to a precipitation step by admixing 0.3 volume of non-solvent precipitating agent such as acetone per volume of uranium. ·Uranium oxide (U30 8) is obtained from this precipitate by calcination for half an hour at 800°C in air. The third portion of the strip solution is neutralized to a pH 6.5 with sulfuric acid to precipitate iron and other contaminants. The solution is further acidified to a pH 1.85 with continuous air bubbling to remove CO2, followed by H2Ch precipitation at pH 3.5 to obtain uranyl peroxide. The latter is reduced by stannous chloride to obtain uranium trioxide dihydrate UO3. 2H20. Identifications, characterization· and purity of these products are carried out by complete chemical analyses, Scanning electron microscope study, tap density determination, X-ray diffraction and infrared spectroscopic investigations. The achieved results agreed well with that of the published data for these nuclear grade purity products.

Jan 1, 2000

By Vasil Kopaleishvili

The bainitic Fe-C-Si alloys with optimum content of retained austenite serve as ?containers? for storing of hydrogen. Both the vacancies of fcc lattice and the possibility of forming hydrides of silicon and other alloying elements will be used. The idea is based on our scientific hypothesis. There is the silicon threshold (Si=0,50%) in "Fe-Si" system and Fe-C bainitic alloys, above which it causes self-organized phenomena: sudden increase of hydrogen solubility and amount of retained austenite in the alloy after ??ß transformation, formation of two supersaturated solid solutions <a??r>, "rejuvenation? and its reverse process. Rapprochement of iron atoms when Si=0,50%, causes appearance of new covalent forces where uncompensated electrons of 3d-subshell are involved and it provokes synergetic phenomena. They ?free? silicon atoms from the previous bonds. After that silicon itself becomes a getter of hydrogen using vacancies (14) of 3P2(6)d0(10) subshell and it results in sudden increase of hydrogen solubility in metal. Simultaneously sudden decrease of iron activity takes place. That in its turn ?releases? the carbon. Thus, its redistribution, controlling the bainitic transformation, is hastened. It stipulates for creation of ?brittle bainite" B[a(C,H)+?r(C,H)] after ??ß transformation. While weathering of metal, "rejuvenating", hydrogen diffuses in ?islets? of retained austenite and ?relaxed bainite? (B[(C)+?r(C,H+H)]) is obtained. When heating austenite ?(C,H) is obtained, and after cooling ?brittle bainite? is obtained, etc. Presented scientific hypothesis explains the available experimental facts ("rejuvenation? and its reverse process, graphitization, weldability, forming of flakes, reaching high strength, etc.) in a new manner, as well as, gives real opportunity for creating of new trends in many fields, e.g. iron based HAA. Provisional data having been obtained are encouraging.

Jan 1, 2006

By Varadarajan Seshadri

A physical model based on similarity principles was constructed for simulating the RH degasser of CST (Companhia Siderurgica Tubarao, Vitoria, ES, Brazil) to evaluate the circulation rate of the metal which essentially defines the degree of exposure of the metal to vacuum in the chamber and thus of the refining rate, The circulation rate on the other hand will influence the decarburization rate and removal of dissolved gases like nitrogen and hence it is essential to optimise this parameter to get maximum refining efficiency with minimum refining times, thus improving the productivity of the secondary refining process. Mixing characteristics in the ladle is evaluated by pulse tracer addition using conductivity-meters located at the down leg as well as at several locations in the ladle. The influence of gas injection through nozzles in the upleg with simultaneous bottom injection of gas as well as nozzle blockage on the circulation rates were investigated. Also simulation experiments of kinetics of decarburization were carried out using CO2 adsorption-desorption process in sodium hydroxide solution as circulating fluid and the effect of, bottom gas flow rate in this case was also evaluated. The results were carried over to prototype and to optimize the process.

Jan 1, 2003

By Yuanyuan Wang, Yuhao Ding, Hao Bai, Kang Zhou, Guangwei Du

"In this paper, the list analysis of GHG emissions of aluminum industry was conducted based on the data from typical electrolytic aluminum plants of a China’s northwest province. The results show that under the conditions of average anode effect coefficient as 0.16 times/(cell• day) and anode duration as 5 minutes per day, equivalent emissions of CO2 reached 1.23 ton per ton of aluminum, in which PFC emissions accounted for about 71%. Compared with foreign advanced level, which is 0.87 ton per ton of aluminum under the conditions of average anode effect coefficient as 0.01 times/(cell•day) and anode duration as 0.46 minutes per day, there is much room for China’s aluminum industry to reduce GHG emissions. Since anode effect plays an important role on PFCs generation in electrolytic aluminum process, how to control anode effect strictly becomes the key factor for remarkable reduction of GHG emissions in China’s aluminum industry.IntroductionTechnology of aluminum electrolysis is a mature and efficient process of aluminum production. Due to the huge demand on aluminum worldwide, so resource consumption, energy consumption and pollutant emissions in the process of aluminum production are still large. The global output of aluminum reached 45193 kt in 2012. A large amount of CO2 and PFCs are produced in the process of aluminum production, and the greenhouse effect and environmental pollution caused by emissions of them is a concern. PFCs belong to a powerful greenhouse gas, thus emission reduction of PFCs is very important for aluminum electrolysis industry. At present, China's aluminum production accounts for about 33% of the world's aluminum production, and controlling PFCs emission has become the key point of pollution control of aluminum electrolysis industry in China [1].Taking the case of a typical electrolytic aluminum plant of a China’s northwest province, this paper studies the list analysis of GHG emissions of aluminum industry in China. GHG emissions of a China’s northwest province were calculated through investigating existing situation of aluminum electrolysis industry in the province, knowing capacity, output, main production technology and equipment level of aluminum electrolysis industry, and using the calculation framework and methods of GHG emissions of aluminum electrolysis industry, which were put forward by the intergovernmental panel on climate change (IPCC), the international aluminum association and other organizations at home and abroad. The list analysis of GHG emissions of aluminum electrolysis industry will offer useful information in promoting emission reduction of GHG in aluminum electrolysis industry, improve the efficiency of energy utilization."

Jan 1, 2014

By Hong-ying Xia, Bao-bao Wang, Jin-hui Peng, Bing-guo Liu, Li-bo Zhang, Zhi-qiang Li

Based on optimization using response surface methodology designed by Box- Behnken, to study the interaction of wet industrial salt with moisture drying temperature (50-90 ); duration (10-50s); and the weight of the materials (20-60g). The results show that: the experimental parameter conforms to the quadratic equation model to influence the moisture content and the dehydration speed., in analyzing the significance and the interaction of various factors, the optimum by the Design Expert software conditions for drying with microwave radiation include temperature of 90 , duration of 10s, and sample mass of 26g. Verified by experiment, the moisture content after drying is less than 0.25% and the dehydration rate reached 1.37g/min, between the predicted value and the actual value confirmed good fitting degree.

Jan 1, 2015

By Björn Saxen

Outotec atmospheric Direct Leaching has so far been implemented for zinc production capacities of around 100,000 t/a. Lately, there has been growing interest for small scale direct leaching plants, producing circa 30,000 t/a of Zn. Such small leaching plants can provide extra front-end capacity in existing roaster-based plants and enable treatment of feed materials not suitable for roasting. In small scale plants the proven OKTOP® 9000 Direct Leaching reactors are not readily applicable, due the large size. For smaller installations a modular approach is proposed providing multiple advantages, such as reducing the construction time and amount of the site work required causing less disturbance to regular plant operation with reduced cost. In this paper, we present advantages that can be achieved by using modular OKTOP®C reactors and discuss also process design when connecting a small scale direct leaching process to an existing zinc plant. Also benefits of direct leaching expansion are presented.

By . Menad Gaballah I

Three samples of solid wastes generated by the non ferrous metallurgy were characterized. These residues contain up to 42 % of valuable metal compounds ( Cu, Pb and Zn ) and 23 %of toxic compounds t As, Hg, Cd and Se ). These sample were subjected to thermal treatments between 200 DC and 800 °C in controlled oxidizing. reducing and chlorinating atmospheres. Up to 99 % of As, Cd, Hg and Se were eliminated from these industrial wastes. Cu, Pb, and Zn compounds were concentrated in the treatments&apos; residues of these samples. A Global Decontamination Factor&apos; GDF &apos; was defined to measure the efficiency of the elimination of toxic elements and the recovery of valuable elements for a specific sample submitted to a given treatment. It seems that the thermal treatment in a reducing atmosphere was the most efficient in decontaminating these solids and the concentration of valuable elements. a.

Jan 1, 1995

By P. N. Anyalebechi

The effects of Si (0.19-0.52 wI. %), Fe (0.20 wI. %-0.44 wI. %), and Cr (0-0.10 wI.%) on the response of ingots of aluminum alloy 3004 solidified at different rates (O.IO°C/s to 30°C/s), to homogenization heat treatment have been investigated. Response to homogenization was determined by quantifying the following microstructural parameters: (i) amount of Mn retained in solid solution; (ii) types, relative amounts, sizes, size distributions, shapes, and chemical compositions of second phases; (iii) extent of the alpha-transformation (i.e., AI6(Fe,Mn) --7 (XAI12( Fe,MnhSi) reaction; (iv) dispersoid formation; and (v) alleviation of dendritic microsegregation. Of the three alloying elements investigated, Si had the greatest effect on the response of aluminum alloy 3004 to heat treatment. Increase in Si content, fineness of cast microstructure, and homogenization temperature facilitated alpha-transformation reaction, dissolution of Mg2Si, loss of Mn supersaturation, and formation of AldFe,Mn)3Si and Mg2Si dispersoids.

Jan 1, 2008

By Lloyd R. Nelson

Selective carbothermic reduction is the preferred method of treatment of electric arc furnace (EAF) dust (listed hazardous waste, K061). The process maximizes the recovery of recyclable constituents by concurrent production of saleable zinc metal (directly condensed from the furnace off-gases), an innocuous, disposable iron oxide-rich slag, and some metallic iron. Results of a mineralogical investigation of a foaming slag produced during selective carbothermic reduction treatment of EAF dusts are presented. Wiistite and tricalcium silicate were identified by reflected light microscopy as the primary crystalline phases contained in a glassy matrix, but this technique failed to reveal any solid phases that could have significantly contributed to foam stability. It was concluded therefore, that the foam had been unstable, and had been primarily generated by copious gas evolution associated with the sudden reduction of the slag by an inadvertent addition of carbonaceous reductant. This is consistent with the susceptibility to foaming, when subjected to sudden excesses of carbon, of the slags produced by selective carbothermic reduction, because they still contain unreduced components such as iron oxide.

Jan 1, 1994

By Saynbaatar, Gangping Ma, Jianhua Fu, Qiqige, Jinghua Wang

The influence on the performance of foam concrete made by replacing cement with some industrial waste residues was researched in this paper. The result shows that the 7d and 28d compressive strength of foam concrete increases firstly and then decreases with the increasing amount of industrial waste residue. The proper added range is 10%-20% for steel slag, blast furnace slag and coal ash, but, 8% for desulfurized fly ash. With the proper adding ratio, the compressive strength of foam concrete always increased comparing with the pure cement foam concrete. When adding 48% of the compound industrial waste residues, the 28d compressive strength of the foam concrete reached the 2.9MPa which could match the pure cement foam concrete. The results indicates that there is a synergistic effect among the compound industrial waste residue, and this effect is benefit to improving the compressive strength of foam concrete.

Jan 1, 2015