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By W. Petruk

A study was performed to determine whether mineral textures affect are breakage during grinding, and to establish a correlation between are breakage and mineral liberation. A base metal are from the Brunswick No. 12 deposit in New Brunswick, Canada was ground for different periods of time in a laboratory ball mill, and both the unbroken are and the ground products were studied by image analysis. Similar size distributions were obtained for material from the 15-minute grind in a laboratory ball mill (K. 0 67 pm), for the grinding circuit discharge from a commercial mill (K. 0 = 59-72 pm), and for pyrite grains in unbroken are (K,. = 74 pm). This similarity indicates that the 1S-minute grind separated weakly adhering pyrite grains along grain boundaries, and represents the limit of easy breakage for the are. At this grind (15 minutes) large discrete are mineral grains and weakly adhering interstitial fillings aIrong pyrite were liberated. On the other hand, the 15-minute grind neither separated rooderately bonded pyrite grains nor released rooderate1y bonded interstitial minerals from pyritei a 45-minute grind (K.. 31 pm) in a laboratory ball mill was required. For Brunswick No. 12 are, a 45-minute grind in a laboratory ball mill (Keo = 31 pm) is equivalent to regrinding in a commercial mill (K ?? Fl:$ 30 pm). Grinding beyond 45 minutes in the laboratory ball mill broke the are by fracturing pyrite across grain boundaries and by Chipping grain edges. Such intense grinding (longer than 45 minutes) did not markedly increase sphalerite liberation. In contrast, the intense grinding increased galena liberation because a significant proportion of the galena occurs as minute inclusions in pyrite. These findings show that ore breakage and coincident liberation depend upon size distributions, intergrowths, and mode of occurrence of the minerals in an ore.

Jan 1, 1988

By T. Ueno

Naoshima Smelter & Refinery of Mitsubishi Materials Crop. commissioned a new Mitsubishi continuous copper smelter in May 1991. Process offgas volume of the conventional reverberatory furnace line, one of the previous smelters having been shut down, was very large and thus two acid plants had been operated. It was expected that the offgas volume would, be reduced at the new smelter to about a half of the sum of those from previous two smelters and the sulfur dioxide strength would be increased. So various alternatives were studied to minimize the operation cost. And it was decided to utilize both of the plants with minor modifications by diluting the gas either with air or with dilute gases. The acid plants now receive off gases from the new copper smelter, a sintering machine of a lead smelter and a decomposer of waste acid. The paper discusses plant design, operation, improvements and modifications realized in relation with the retrofitting of the copper smelter.

Jan 1, 1992

By Dmitri Nassyrov, In-ho Jung

"All relevant thermodynamic and phase diagram data in the CaO-Fe10-CaF2 system were critically reviewed. One set of model parameters describing the Gibbs energy of all phases has been obtained as a result of critical evaluation of the available data and optimization of the model parameters. The Modified Quasichemical Model was used to describe the interactions in the liquid phase. All calculations were performed using the FactSage thermochemical software.IntroductionSlags contaimng CaF2 are of significant interest to the steelmaking community. Notable examples of slags containing significant amounts of CaF2 include Electro-slag Remelting (ESR) slags [1] and mould flux for continuous casting [2]. The role of these slags is, among other things, to refine steel by absorbing inclusions and dissolved impurities. During slag-steel interaction, some iron from the steel will inevitably get oxidized and form iron oxides which will dissolve into the slag. With this in mind, it is important to understand the interaction between CaF2 and Fe,0 for accurate prediction of slag composition and process optimization. A thermodynamic optimization of the CaO-FetO-CaF2 was thus undertaken."

Jan 1, 2013

By J. A. Bakken

Thermal plasmas are interesting for a wide range of metallurgical and chemical processing applications. The 300 kW experimental reactor PRESS, which has been in use since 1987, is operated in the transferred arc mode with three or one plasma torches . Tests include remelting of silicon fines and production of ultrafine silica. Work on a novel three stage process for production of silicon metal is under way. A 1:1 model of the plasma reactor is used to measure the wall heat flux distribution calorimetrically. The cold walls of this model are divided into several water-cooled sections. The same plasma torches as in the real hot-wall reactor are used. In parallel to the experiments and calorimetric measurements theoretical work is done on numerical modelling of one and three transferred arcs. A modified version of the flow simulation program FLUENT from Creare Ltd. is used.

Jan 1, 1991

By R. R. Odle

A laboratory and pilot-scale investigation of direct smelting of copper concentrates was conducted to determine the effect of concentrate analysis and the degree of roasting on the yield and quality of copper produced in a subsequent smelting step. A stoichiometric :mOdel of direct smelting is presented which predicts the? quantity of copper; slag, and white metal' prOduced'and the distribution of copper in these phases as a function? of the concentrate '(calcine) analysis.

Jan 1, 1983

By Y. Ikeda

Typical electric appliances were dismantled into component pieces to study the recyclability of these discarded goods. Types and weight ratios of these component materials were investigated and characterized. The results showed that if they are dismantled properly, these goods could be classified into several groups of similar materials and/or structures, namely those consisting of single materials, metal-plastic combinations, metal-metal combinations and complex combinations of many different materials. By separating each combination into recyclable materials and isolating hazardous materials, it was found that the final waste for disposal could be reduced and the recycling efficiency could be improved markedly as compared to the conventional shredding method. The metal-metal combinations account for 60% by weight of the total metal contents in electric appliances, and therefore, it becomes important to segregate these metals. For the complex combinations, a process consisting of pyrolytic decomposition of plastic contaminants followed by smelting of the residue is proposed. It is anticipated that nearly zero-emission recycling of electric appliances will be achieved by applying this treatment process.

Jan 1, 1995

By Larry Hopkins

The molten metal circulation pump has become a staple for melting aluminum in reverberatory furnaces. The forced convection that is created in the melt efficiently provides circulation while dramatically improving melt rates, lowering fuel consumption, extending refractory life, and providing metallurgical homogeneity. Two metallurgical guidelines that are important to many casthouses are molten metal inclusion levels and hydrogen gas content. In order to improve molten metal quality, furnace and casting practices must 'manage these molten metal defects, Today specialized in-line degassing and filtration equipment is used downstream of the furnace to accomplish these tasks. In contrast, the molten metal gas injection pump has metallurgical contact time in the process for hours during the charging/homogenization cycle. The qualitative benefits of employing a gas injection pump to "pre-clean" are outlined and discussed against historical empirical information obtained with alternate methods. Further, a recent study quantifies the merits of this gas injection technique as an effective molten metal quality improvement tool. Specifically, the effects on inclusion level as determined by PoDFA?, gas content as determined by A1SCAN? sampling and alkali metal content as determined by spectrographic analysis are examined in relationship to various gas feed compositions and flow rates.

Jan 1, 1995

By Torben L. Edens

Norddeutsche Affinerie is the largest copper producer in Europe. Two sites are in operation for the production of refined copper: primary copper production is located in Hamburg and secondary copper production in Lünen. A total of just under 560,000 tonnes of copper cathodes is produced annually at the two sites. Primary copper production using the flash smelter furnace has been in operation in Hamburg since 1972. Over the years, the capacity of the flash smelter has been increased in three expansion projects from 120,000 t to almost 500,000 t of anode copper p.a. The anode sector consisting of two anode furnaces and a 24 mould casting wheel still features just about the same equipment as in 1972. The paper describes the most important steps taken to optimise operation which have put NA in a position to cast meanwhile more than 500,000 t of anode copper annually with the two anode furnaces and 24 mould anode casting wheel.

Jan 1, 2006

By A. Andreas Hejja

Flow of slag and settling of matte in slag resistance electric furnaces are discussed in conjunction with furnace geometries, stirring action of the electrodes, buoyancy and electromagnetic effects. The rectangular electric furnace was regarded as a channel reactor and the mode of slag flow as a channel flow. The flow is affected both by buoyancy and electromagnetic forces, however the effect of electromagnetic forces is minimal. The flow velocity is made up of two components; (i) that developed by the action of the electrodes, and (ii) the bulk flow velocity determined by the smelting rate and the volume of the reactor. Slag samples were taken from various depths of the molten bath and were analyzed microscopically to determine the size and distribution of matte particles, The action of the electrodes was described by a simple mathematical formula indicating a balanced settling rate in the area of electrode action.

Jan 1, 1996

By Goran Vukovic

The use of gas purging plugs in the copper industry is a widely used practice. They provide substantial improvements especially in anode refining furnaces, where savings in process time and energy are obtained as well as refractory wear and buildups inside the furnace are minimized. The newly developed system, enables purging plugs to be implemented in both stationary and tilting furnaces, is in operation in vessels on three continents. An additional advantage in these furnaces above all other benefits is the significantly improved melting rate. This innovative and patented gas purging system consists of a purging plug cooling device and a slidable, cooled piping system. It provides compensation for any thermal expansion in the furnace lining and minimizes the risk of undesirable copper infiltration. User experiences and results of this widely used system are reported in this paper.

Jan 1, 2014

By J. M. Boxall

The electrolytic zinc plant at the Bartlesville division of Z.C.A. originally used lead anodes containing only 0.25% silver because only H.G. zinc and alloy was to be produced. In 1984, a small addition of strontium carbonate was made to control the surf ace morphology of the cathodes which reduced short circuits and increased current efficiency. Later a drastic reduction in colloid addition further reduced short circuits. Increased strontium additions allowed the production of some S.H.G. zinc. Increasing the silver content of the anodes reduced the lead in cathodes only slightly. More important, the anode scale that was not removed during anode cleaning, entered the electrolyte and contaminated the cathodes with lead. A piping system has been installed to purge the contaminated electrolyte directly back to the leaching section. This has allowed the plant to produce S.H.G. zinc consistently.

Jan 1, 1990

By Fang-Qui Zu

Understanding the nature of liquid structures and properties remains an open problem for many fundamental and applied fields such as materials sciences and processing. And as well known, there is no other defined phase line above liquidus (TL ) in phase diagrams of ordinary binary systems. However, via different experimental resorts, our research results on over 30 metallic melts including alloys and elements show a novel physical image: temperature induced liquid-liquid structure transition (TI-LLST) can occur hundreds of degrees over TL. On the other hand, the solidification behaviors and structures out of the melts experienced TI-LLST are distinct from those out of the melts before TI-LLST. In this presentation, some characteristic aspects of the TI-LLST and the effects on solidification behaviors and structures are briefly summarized, and the pertinent rules and mechanism are also analyzed.

Jan 1, 2009

By S. Ozbilen, B. Erdogan, M. Erdogan

To study by thermal analyses the response of precipitation hardenable alloys of Al-Cu-Mg and Al-Li-Cu-Mg system to natural and artificial ageing, a series of ternary and quaternary Al-alloys with nominal compositions of Al-l.13wt%Cu-0:65wt%Mg (alloy-I), Al-1.15wt%Cu-0.57wt%Mg-0.07wt%Li (alloy-2), Al-l.19wt%Cu-0.56wt%Mg-0.75wt%Li (alloy-3), Al-2.0lwt%Cu-0.89wt%Mg (alloy-4), Al-2.14wt%Cu"0.56wt%Mg-0.07wt%Li (alloy-5) were used in the present investigation. Samples in the form of rolled sheets are subjected to water quenching at 25EC after solution treatment at 530EC for 20 min. Alloys were aged naturally at room temperature (25EC) up to 2 months and artificially at 190EC up to 2 days. By using differential scanning calorimetry (DSC) in the temperature range of25-300EC, differential thermal analysis (DTA) in the temperature range of25-600EC together with Vicker's hardness measurements, the response to natural and artificial ageing of the alloys used in the present study were investigated. It was observed that in these alloys, GPB(Cu, Mg) zones [Guinier-Preston zones with Cu and Mg] do form during water quenching at 20EC following solutionizing heat treatment. Natural ageing of the same alloys causes formation of more GPB(Cu, Mg) zones, which results in hardening in the alloys. Artificial ageing at 190EC up to l day results in GPB zone dissolution causing preliminary decrease in hardness values while two days of artificial ageing in the alloys cause S' (Al2CuMg) precipitation confirmed by DSC/DTA analyses resulting in an increase in hardness values. Li addition up to 0.75wt% helps T1 (Al2CuLi) and T 2 (Al6CuLi3) phase formation together with S' precipitation as DSC/DTA analyses show after the same heat treatment.

Jan 1, 1998

By T. T. Chen

A mineralogical study of copper anodes and copper anode slimes was carried out to elucidate the silver phases present and the behaviour of silver during copper electrorefining. Most of the silver in the anodes is in metastable solid solution in the copper metal. As the copper dissolves, silver also dissolves, but is rapidly removed from solution by a variety of reactions. Some of the silver is precipitated as Ag by cuprous ions and some is precipitated as a complex CU-Ag-Pb-As-Se oxidate phase. Much of the silver, however, reacts with copper selenides to form, progressively, (CU,Ag) 2se, AgCuSe and Ag2se. The reaction commences at the periphery of the selenide grains and progresses inward; the result is commonly a silver-rich species on the outside of a silver-deficient core. Slimes collected periodically throughout the electrorefining cycle show a progressive silver enrichment of the selenides. Traces of Ag2Te also may be present, but the telluride seems to J:ie a rare constituent of most raw anode slimes.

Jan 1, 1989

By C. B. Catanach

The development and in place leaching of a chalcocite ore body at Mountain City, Nevada is described. Block caving was used to induce permeability while ore removed during development was leached in heaps on the surface. Copper was recovered by precipitation on iron. Excess ground water which seeped into the mine was pumped into a deep disposal well. A parallel system was used to purify water by lime neutralization. Copper extraction was at an annualized rate of 11% during the first six full months of underground leaching and totalled approximately 30% during six months of heap leaching. Leach solution flow and distribution had a major effect on extraction rate. Enrichment of leach solutions with ferric sulfate did not produce conclusive results until analyzed with the aid of a leaching model.

Jan 1, 1976

By Nicola Baldo, Marco Pasetto

"Recycling of tyre rubber in the road pavement, may be one of the best way to reduce waste tires in large quantities and, at the same time, improve some engineering properties of asphalt mixtures. The paper discusses the results of an experimental study, developed in order to analyse the potentialities of crumb rubber from road tyres in bituminous mixtures, using the dry process. Two types of porous asphalt mixtures and reference mixes without rubber were formulated by the traditional Marshall methodology, and mechanically evaluated by means of the Indirect Tensile Stiffness Modulus test, the Creep test (with confinement), and the Indirect Tensile Fatigue Test. Results of this study indicate that the tyre rubber has a positive influence on the performance characteristics, depending also on the grading and volumetric properties of the mix being studied: an interesting increase of the fatigue life, a better stiffness behaviour at lower temperatures and a bigger permanent deformation resistance at high temperatures are guaranteed. Introduction Recycling the rubber from used tyres, in the construction of road pavement layers, is potentially one of the more interesting and advantageous solutions from both the technical and environmental points of view, in order to reduce the total amount of car and lorry tyres to dispose. In road-building techniques, a technology, termed “wet”, for modifying bituminous binders with crumb rubber has by now become well consolidated. There have been numerous scientific studies conducted on this technology and its applications, particularly in the United States, where it has been adopted and codified in specific technical regulations (ASTM D-6114). If the wet process can be considered amply tested, the same cannot be said for a second technology, termed “dry”, which deserves careful study to evaluate its suitability and advantages. In “dry” processes, the rubber is usually used as a partial substitute of aggregate of equivalent grading and mixed with bitumen after integrating the crumb rubber in the lithic skeleton."

Jan 1, 2008

By Joseph Goodwill

1. PURPOSE The objective of this paper is to summarize a study undertaken by the EPRI Center for Metals Production (CMP). The overall purpose of the study was to identify electrolytic opportunities that might merit consideration for joint development by industry and EPRI. 2. SCOPE The electrolytic technologies of interest to this study include: Electrorefining, Electrowinning, and Fused-salt electrolysis. Recovery from primary, secondary, and waste materials were included in this effort; however, we excluded from consideration: Plating and coating operations, such as electrogalvanizing; Mining and milling operations in which electric energy is predominantly used for comminution; Electrothermal processes in which submerged-arc, open electric-arc, and plasma-based smelting processes use electric energy largely to provide a melting or refining ("heating") capability; and Aluminum electrotechnologies since these were the subject of a separate study (CMP 86-2). We recognize that there may be some "gray areas" between these excluded areas and the electrolytic sectors of interest. For this reason, a secondary criterium was used, namely, if the major use of electric energy was to extract or refine the

Jan 1, 1990

By John J. Dunkley

Recent years have seen the increased use of hydrometallurgy in the smelting and refining of metals. However this is often used as a final refining step, following an initial pyrometallurgical smelting process. Huge amounts of material are produced as melts which have to be cast, comminuted, and taken up into solution or leached. A common method is to granulate the melt and then grind it. In the case of metallic melts this can be difficult or unfeasible due to the ductility of the granulated particles. Water atomisation is capable of replacing the granulation and grinding stages with a single process step that can process in excess of 30tlhour of melt into particles as fine as 50 microns. Applications in operation in Co, Cu, Ni, Ag, Au, Pt and Rh refining are discussed together with potential applications in copper smelting.

Jan 1, 2003

By Huimin Lu, Shi Zhou, Lisha Yang

"The Zeolitic imidazolate frameworks (ZIFs) were successfully synthesized by applying a combination of ionothermal synthesis and microwave energies for rapid synthesis. The synthesis was proceeded under various conditions including different raw materials, reaction temperature as well as microwave irradiation time. Zeolitic imidazolate frameworks (ZIFs), also known as coordination polymers, are new type of porous materials formed by inerratic polyhedral in three-dimensional. They are the ideal crystalline substances for gas separation and storage. The assynthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and C02 adsorption test. Results illustrated that the synthesized samples had stable structure, high thermal stability (up to 530 °C) and C02 adsorption capacity (10.2 cm3/g at 0°C under ambient pressure). This novel method also showed great advantage with high energy efficiency, safe synthesis conditions, and rapid crystallization time (60 minutes).IntroductionNowadays, carbon dioxide capture has become imperative due to the global warming caused by the increase of C02 in the atmosphere, especially produced by the concentrated sources such as power plants [1]. Zeolitic imidazolate frameworks (ZIFs), also known as coordination polymers, are ideal crystalline substances for gas separation and storage due to their structure diversity, high thermal and chemical stability [2-5]. They are formed by inerratic polyhedra in threedimensional with large cages and small apertures. Traditionally, ZIFs are synthesized by solvothermal method in a sealed autoclave under autogenous pressure [6-9]. However, in order to generate the products, the solvothermal temperature should not be lower than 100°C according to the sovlothermal mechanism. Moreover, at such a temperature, molecules with a low boiling point (such as water) may generate high pressure in reactor which might cause danger [9]. Thus the synthesis requires the equipment to possess resistance to autogenous pressure and corrosion. Further, conventional solvothermal methods need a long time to prepare products, usually a few days, which is a large energy consumption and inefficiency. So it is interesting to synthesis ZIFs through other ways under mild reaction condition with high energy efficiency."

Jan 1, 2012

By Katsutoshi Inoue

The sulfuric acid leaching of spent hydrodesulfurization catalysts yields an acidic solution rich in rare metals such as molybdenum, vanadium, cobalt, and nickel in addition to aluminum. For the purpose of separating and recovering the rare metals from the solution, basic solvent extraction characteristics of the metals involved with commercially available acidic organophosphorus reagents like TR-83, PC-88A, PIA-8 and CYANEX 272 as well as aliphatic alpha-hydroxyoxime LIX 63 from sulfuric acid media were investigated in the present work. It was demonstrated that CYANEX 272, PIA-8 and LIX 63 possessed excellent selectivity for molybdenum and vanadium over the other metals at comparatively low pH. Further, recovery of molybdenum and vanadium from the total leach liquor by the selected extractants was discussed. Additionally, in order to achieve preferential separation and recovery of cobalt and nickel over an appreciable amount of aluminum from the raffinate obtained after recovering molybdenum and vanadium, a systematic investigation was conducted on synergistic extraction behaviors of the mixed solvents of LIX 63 in combination with a series of acidic extractants such as CYANEX 272, PIA-8, PC-88A, D2EHPA, TR-83 and OPEHPA for cobalt, nickel and aluminum. It was elucidated that all of these mixtures could exhibit a good synergistic effect for extraction of cobalt and nickel, and that the lower the pKa of the acidic extractants, the greater the synergism. Contrarily, the extraction of aluminum, was considerably suppressed by LIX 63. Effective extraction of cobalt and nickel away from aluminum was accomplished from the sulfate solution at low pH (1.0 - 2.5) with the mixtures. In particular, the mixtures consisting of LIX 63 and CYANEX 272 or PIA-8 appeared to be the most feasible and economic from an industrial point of view, yielding acceptable separation efficiency for cobalt and nickel over aluminum and .a low acidity requirement for stripping cobalt and nickel as well as negligible degradation of LIX 63. Aluminum can be readily recovered as sulfate salt from the raffinate obtained after recovering molybdenum, vanadium, cobalt and nickel as outlined above by conventional crystallization method.

Jan 1, 1995