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By James P. Bennett, Jasper Kwong

As concerns about the environment and the disposal of industrial wastes increase, the utilization of spent refractories from electric arc furnaces (EAF) is receiving more attention. Longer service life of refractories in an EAF can be achieved by foaming MgO saturated slag. The refractory wastes removed from a melt shop can be utilized as a part of these slags. The Albany Research Center is conducting research on recycling spent basic refractory materials as EAF slag conditioners. A good foaming slag should be a creamy, MgO saturated slag, which contains some solid particles (MgO-FeO). A computer model was developed to calculate the dual saturated slag chemistry with respect to CaO and MgO, the MgO saturated slag chemistry, and the solid content in solution. The effects of C/S ratio, AhO3 and temperature on the MgOsaturated slag as calculated by the model will be discussed.

Jan 1, 2000

By M. Hadj Meliani

This paper explores direct use of finite element analysis by CASTEM 2000 in order to determine the evolution of T-stress term for arc of pipe specimens with external surface crack. A simple method, called the stress difference method proposed by Yang (1999), is used to compute the elastic T-stress in mode I at a crack tip. The different crack geometries and length-to-thickness ratio on T-stress and stress-intensity factor (SIF) are examined. The revisited stress difference method is shown to be an accurate and robust scheme for evaluating T-stress in arc of pipe.

Jan 1, 2006

By Xiao-dong Xiang, Hong-bo Jin, Ming-sheng He, Huo-guo Pang, Can-hua Li

The specification of the steel slag aggregate will be mutated if the ag- gregate is prepared by a single type crusher. The specification stability of the steel slag improved significantly when the jaw crusher and the cone-crusher are com- binedinthecrushingprocess.Thecombinationofthecrusherandscreenisapplied to produce steel slag aggregate while the roller washing process for removing the dustfromthesurfaceofaggregate.Apilotproductionlinehasbeenestablishedby this technology. The specification stability and the road performance indicators of thesteelslagaggregateshavebeengreatlyimprovedbythispilotproductionlineas compared with the traditional production line. The particulate of the steel slag aggregate is decreased by 81% compared to the traditional line. (cid:1) (cid:1)

Mar 1, 2018

By David C. Lynch

The molecular form of trace elements in matte has been shown to depend on the chemical potential of sulfur and the propensity of the trace element to form a sulfide. Of the four trace elements (As, Sb, Bi and Pb) arsenic and lead behave nearly as opposites, with lead readily forming a sulfide while arsenic forms complexes with free copper and ion in the matte. Antimony and bismuth both display the dissolution characteristics as As and Pb, suggesting that these elements dissolve in matte in multiple forms of significant concentration. While in the present investigation the dissolution characteristics of all four trace elements are examined, the primary focus is on the multiple dissolution behavior of Sb and Bi.

Jan 1, 1995

By Takahiko Okura

"It is said that the energy and resources crisis will come before long because the lifetime of known deposits of crude oil and common metals such as Pb, Zn, Cu is estimated to be less than 50 years. Establishing the sustainable society by means of resources-recycling has become an absolute necessity.The non-ferrous metals industry in Japan has been involved in the resource- recycling business for many years, along with the introduction and enforcement of various legislations to preserve the environment and natural resources. Including process-linkage during various manufacturing activities, the non-ferrous metals industry, the iron-making and cement industries are treating considerable amounts of recycled materials and wastes, in an environmentally-sound and economic manner.The Mining and Materials Processing Institute of Japan has submitted “The present and issues in Japanese non-ferrous metals and recycling industries.”The topic of the paper is to highlight the actual conditions within the resources-recycling structures and the present issues.IntroductionGlobalization has been changing the world, introducing the spike of energy and metals price. In addition, the preservation of the environment has also been strongly facing the crisis and many people have been aggrieved by both shortage and the increment in the price of the meals.In the world of metals, even though their reserves are coming depleted, the production rates are increasing, and then the industry has to enhance their productivity under stricter environmental regulations. The Japanese industry experimented the same scenario some 40 years ago, facing big pollution problems, but concurred them and enhanced the technology to overcome the more severe regulations. It will be fruitful to present the current situation in the Japanese industry for the world. The present issues are also presented."

Jan 1, 2008

By K. S. Barros, D. C. R. Espinosa, J. A. S. Tenório

Over the past several decades, electrodialysis membranes have been employed for the removal of metals from galvanizing industry effluents. However, for its technical viability, it is useful to know some properties of the system to avoid, for example, precipitation of inorganic salts, destruction of the membrane and an increase in the energy consumption. The scope of the present study is to use chronopotentiometry to determine limiting current densities, transition times and resistances of the cationic membrane HDX 100 using a synthesized solution of the galvanizing industry effluent prepared with copper sulfate and sulfuric acid in different concentrations: 0.1, 0.5 and 1.0 g/L of Cu +2. The current-voltage and chronopotentiometric curves obtained have clearly defined regions and it was verified that the Cu+2 concentration causes a significant increase in the limiting current densities and in transition times. However, a high decrease in resistance occurred because at the highest concentrations, it is more difficult to reach the zero concentration value at the membrane surface. Besides, the pH increase causes a significant decrease in the limiting current density and in the transport number, but a slight increase in the resistance due to the presence of hydrogen. The results obtained confirm that the chronopotentiometry method is a valuable tool to determine membrane properties.

Mar 1, 2017

A full-scale test of chalcocite heap bioleaching was undertaken at Straits? Nifty Copper Operation. Straits worked closely with the CSIRO to investigate the chemical and biological changes over the life cycle of this chalcocite heap bioleach system. Results indicated nearly 80% copper recovery was achieved in just over 300 days. Significant changes in iron chemistry and microbiological activity were detected. Temperatures in the heap reached as high as 70 ºC during the time of maximal copper recovery rate. The dominant cultivatable bacterial strains were typical mesophilic bacteria, however, naturally occurring moderately thermophilic bacteria were detected by culture and culture independent molecular (PCR followed by denaturing gradient electrophoresis [DGGE]) and signature lipid methods. Signatures for the iron and sulfur-oxidising species Acidithiobacillus ferrooxidans and Sulfobacillus spp., as well as the moderately thermophilic heterotroph Alicyclobacillus sp. were detected. Biomass was greatest in ?warm? but not ?hot? parts of the heap, and Hyperthermophilic Archaea were not detected.

Jan 1, 2003

By D. Neuschiltz, M. Witthaut, R. Cremer

"Metastable (Ti,Al)N coatings with fee structure have been shown to exhibit superior performance as compared to TiN under conditions of wear at elevated temperatures due to their better oxidation resistance and hardness. The oxidation resistance of these coatings increases significantly with increasing Al-content. However, the deposition of (Ti,Al)N films with Ti/ Al ratios below about 30/70 leads to a hexagonal structure which is not suitable for tribological coatings. Only little is known about the location of the cubic to hexagonal phase transition and hence about the optimum composition of (Ti,Al)N hard coatings.To determine the position of this transition, Tii-xAlxN films with different Ti/Al ratios were deposited on high speed steel at substrate temperatures between 100 and 700 °C by means of reactive MSIP. The composition of the films was determined by electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS), the crystallographic structure by thin film X-ray diffraction (XRD).It could be shown that in case of deposition temperatures of 300-700 °C a two-phase region exists in the metastable TiN-AlN phase diagram, which expands with increasing temperature, wheras at 100 °C substrate temperature no two-phase region was observed. But in opposition to the phase diagram known from literature, which is based on thermodynamic estimations, the detected two-phase region is narrow for typical PVD temperatures, thus allowing the deposition of cubic single-phase Al-rich (Ti,Al)N hardcoatings for tribological applications. Based on these results, a new Ti1-xAlxN film with x = 0.62 has been developed, which showed an increase of oxidation resistance by a factor of 4."

Jan 1, 1998

By Michael G. King

The primary non-ferrous metals industry is the principal supplier of the minor metals selenium, tellurium and bismuth. It is also a major supplier of antimony. These minor elements are recovered from by-products of base metals production. To ensure that these elements remain available, the cost of production must be compatible with four other factors - method of production, available supply, technological niches, and product stewardship. This paper first describes the relationship between the copper industry and the production of tellurium and selenium. The more complex relationship between the lead industry and bismuth production is then discussed, followed by comments on antimony availability. Product stewardship programs are essential to the growth or certain specialized markets for these metals. Smelters and refineries of non- ferrous metals will play a major role in the recycling of scraps and wastes from these markets. Examples on how such materials can be recycled are given in the paper.

Jan 1, 1995

By K. Twite, K. Mujinga, J-M. Dereydt, P. Louis

"GECAMINES is a large mining concern and the world's leading cobalt producer having some of the richest cobalt deposits in the world. Cobalt is associated in the ore with copper as sulphides and oxides and in some locations with nickel too. Specific hydrometallurgical processes have been developed by GECAMINES which had done an important contribution to the development of the cobalt hydrometallurgy.In the Shituru plant, cobalt is obtained from an unique in-pulp electrolysis process, while in Lullu, cobalt is electrolyzed in a clear acidic solution giving a purer deposit. In the beginning of 1996 Shituru started the treatment of mixed Cu-Co-Ni Shinkolobwe hydrates obtained as by-product of an uranium solvent extraction plant. A typical analysis of this feedstock is: 2% Cu, 8% Co and 4% Ni.The nickel sulfide depolarized cementation process developed previously by GECAMINES was inefficient to treat such a high level of nickel contamination and it was decided to produce alloyed Cobalt-Nickel cathodes in the Shituru tankhouse.As anticipated from laboratory tests as previous studies and publications, a lower Ni/Co in the deposit was obtained compared to the Ni/Co ratio solution, despite the nickel reversible electrochemical potential is somewhat higher than the one of cobalt (-0.25 V vs -0.28 V).In this paper, the process flow-sheet and production data are given. Cobalt alloy with 5 - 20 % Ni was obtained at a production level of 300 t per month. The process developed is a new contribution to cobalt hydrometallurgy."

Jan 1, 1997

By M. M. Salari Rad

An investigation of gold distribution in the mill products of Sar Cheshmeh beneficiation plant demonstrates that on average 44% of the gold is routinely recovered as a by-product in the copper concentrate, and the remaining is lost to the tailing. In order to evaluate the causes of gold losses, the distribution and mode of gold occurrence in the Sar Cheshmeh ore and mill products were studied. Searching for gold within samples and within individual grains of sulphide minerals was carried out by SEM in the backscattered electron mode and SIMS, respectively. The mineralogical distribution of gold revealed by microbeam techniques were combined with the results of relevant metallurgical experiments including, sizing, heavy liquid separation, and diagnostic leaching tests, and the nature and location of gold in the ore and mill products were determined. The combined results of the experimental approaches pursued suggest that while there are some gold in solid solution and/or -colloidal size within sulphides of the Sar Cheshmeh ores, "visible" gold is the principal form of gold occurrence at Sar Cheshmeh.

Jan 1, 1999

By Tong Zhilin

The reasons why the pits were formed on the cathode in the process of Ni electrowinning and the methods how to prevent these pits from forming are described. Some examples are presented. It has 'been proven that P507 and P204 present in the electrolyte can effectively prevent pits from forming on the cathode.

Jan 1, 1993

By G. Ramadorai

"This paper addresses processing options for recovering gold from carbonaceous sulfidic gold ores. These include, but not limited, to the following methods: (1) Hypochlorite pretreatment followed by cyanidization; (2) Chemical blanking agents pre-treatment followed by cyanidization; (3) Non-cyanide heap leaching techniques; (4) biological pre-treatment followed by cyanidization; (5) biological pre-treatment followed by non cyanide heap leaching. Issues of costs, economics, recoveries, testing methods, state of advancement etc., will be discussed in the paper.ABSTRACT ONLY"

Jan 1, 1997

By Giovanni Principi

The activity of the ?Hydrogen Group? of Padova University, addressed to the study of materials for solid state hydrogen storage, is illustrated. Various Mg-based materials have been considered and are being studied: a) MgH2 and 0.5% mol Nb2O5 mixture ball milled under argon atmosphere; b) Mg-Ni-Fe intermetallic compounds prepared by short time ball milling of ribbons obtained by melt spinning and by long time ball milling of a mixture of MgH2, Ni and Fe powders; c) MgH2 ball milled in argon with Mm-Ni-Al (Mm = La-rich mishmetal) and Zr-Cr-Fe catalyst alloys. All the samples have been structurally characterized by X-ray diffraction (Rietveld refinement) before and after hydrogen absorption/desorption cycling and tested with a Sievert apparatus as regarding their thermodynamic and kinetic properties.

Jan 1, 2006

By M. Frades, C. Frías, G. Díaz, A. B. Mejías

"In recent years, zinc recovery from flue dusts and other industrial wastes has been increased, offering to the market a large tonnage of secondary zinc oxides, which can not be processed directly to render high quality zinc because of the hazardous impurities and halogens content.The ZINCEXTM Technology has been commercially applied for more than thirty years and represents the most suitable solution to deal with secondary or crude zinc oxides due to its flexibility, simplicity, and cost-efficiency, allowing production of SHG electrolytic zinc and pure zinc sulfate salts thanks to the flexibility and selectivity of the zinc solvent extraction unit regarding to get rid of impurities.A dual plant able to produce electrolytic zinc and crystallized zinc sulfate has been engineered to provide a flexible and profitable solution to zinc market. A description of the study and the relevant achievements is presented in this paper.IntroductionZinc is a valuable commodity in the marketplace and can be recycled again and again and still maintain its physical and chemical properties. Zinc recycling offers both environmental and economic benefits such as reducing volumes of material that end up in landfills, saving energy by reducing the need for mining and smelting, and relieving environmental impact on the land and water, and conserving zinc ore [1].The supply of zinc able to be re-processed will be increasing from year to year according to secondary materials enter the recycling stream, and as a result, more recycled zinc will become available in the market. Thus, some existing zinc refineries are implementing an annexed treatment line to process secondary oxides in conjunction with primary zinc concentrates [2].The galvanized steel scrap is normally recycled in electric arc furnaces or in basic oxygen furnaces, which generates a large tonnage of zinc-bearing flue dusts (EAFD). Around one million ton EAFD is yearly produced at the USA and the EU, respectively. The flue dusts are treated commercially by pyrometallurgical ways such as waelz kilns, electrothermic furnaces, etc, to yield secondary zinc oxides that can not be processed directly to render high quality zinc because of the hazardous impurities and halogens content [3]."

Jan 1, 2008

By A. R. Laplante

Recent developments in gold metallurgy are used to illustrate how the interface between gravity recovery and hydrometallurgy has evolved in recent years. Of particular interest is the use of gravity recovery to produce high-grade concentrates that can be subjected to intensive cyanidation. It is expected that a growing proportion of gold production, possibly close to 50% in certain countries, will follow this route. Other examples of the interaction between gravity recovery and cyanidation are also provided. Implications for new and renewed research directions are discussed.

Jan 1, 2003

By Natasa Mitevska

The statistical analysis of the slag composition influence on copper losses to discard slag in the reverberatory furnaces No.1 and No.2 in the RTB BOR, Copper Smelter and Refinery (Yugoslavia) is presented in this paper. The model for the slag basicity calculation is determined, and connected to the copper distribution coefficients between the matte and slag phase. The influence of all components on the slag structure is also illustrated.

Jan 1, 2003

By Damien Wagner

To reduce the emission of greenhouse gases by the steel industry, particularly for ironmaking, the production of DRI (Direct Reduced Iron) using hydrogen as the reducing gas instead of carbon monoxide is being considered. In this context, the reduction of pure hematite by hydrogen was studied at the laboratory scale, varying the experimental conditions and observing the rate and the course of the reaction. All the reduction experiments were performed in a thermobalance and supplementary characterization methods were used like scanning and transmission electron microscopy, X-ray diffraction, and Mössbauer spectrometry. The influence of rising temperature in the range 550-900°C is to accelerate the reaction; no slowing down was observed, contrary to some literature conclusions. A series of experiments consisted in interrupting the runs before complete conversion, thus enabling the characterization of partially reduced samples. Interpretation confirms the occurrence of three successive and rather separate reduction steps, through magnetite and wustite to iron, and illustrates a clear structural evolution of the samples. Finally, the influence of the sample type was revealed comparing a regular powder, a nanopowder and a sintered sample. The regular powder proved to be the most reactive despite its larger grain size, due to a more porous final structure.

Jan 1, 2006

By John D. Kinton

A patent is a right granted by the government to exclude others from making, using, selling, offering to sell, or importing a claimed invention. Once the right is granted, the patentee may use the U.S. Federal Courts to enforce that right. Reading a patent from a litigation perspective is quite different than reading it from a technical perspective. The Judge's interpretation of the claims will affect their scope, and likely the ultimate outcome of a patent case. Additionally, the patent right can be challenged. If done successfully, the patent can be rendered invalid or unenforceable. The likelihood of success, and well as the achievement of other litigation goals is often influenced by the forum where the litigation is initiated. Finally, patent litigation costs are significant, and will weigh heavily in the decision to file (or fight) a patent lawsuit.

Jan 1, 2006

By David G. Dixon

From its first implementation for the recovery of gold from low-grade ores by cyanidation in the early 1970s, heap leaching has developed into a key hydrometallurgical technology, in conjunction with solvent extraction and electrowinning, for the recovery of base metals, including most notably copper from both oxides and secondary sulphides, and more recently, nickel and zinc. And, given recent advances in bioleaching with thermophilic microbes, the successful application of heap leaching technology to low-grade primary copper ores seems only a matter of time. However, with each new development, it becomes increasingly apparent that the successful application of heap leaching technology will ultimately depend on our having an ever more complete understanding of the fundamental processes underlying it. Much work has been done toward the development of this understanding, on many different fronts. In this paper, a critical overview of heap leach modeling work to date is presented in terms of the most important phenomena which occur during heap leaching, and potential directions for future work are discussed.

Jan 1, 2003