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By P Hulteberg

In this article, an integrated catalytic reactor design approach to produce PEMFC-quality hydrogen is evaluated. The design is based on a high level of heat exchanging perfonned internally, highly active noble metal catalysts and a woven wire mesh catalyst support system. It consists of an integrated steam refonner and a catalytic burner section, a water gas shift section and a preferential carbon monoxide oxidation section. The reactor design is described and experiments perfonned to evaluate the two reactors built are reported. The two reactors have a maximum output of 3 Nm and 10 Nm3 hydrogen/h respectively. In the larger unit, a total of six fuels, three gaseous (methane, natural gas and liquid propane gas) and three liquid (naphtha, ethanol and methanol), were evaluated. The larger unit was also used to investigate how variations of parameters such as steam-to-carbon ratio in the steam reforming part of the system and the relation between oxygen and carbon monoxide in the preferential carbon monoxide oxidation affect the reactor perfonnance. The smaller unit was used, after implementing automatic control, to run a system life time test for 480 h. The refonner system perfonned according to specifications on almost every aspect.

Jan 1, 2005

By M. Oliazadeh, A. Vazirizadeh

"The inclusion of small amounts of silicon, phosphorus and sulphur in iron ores or concentrates can have a profound effect on the steel making process and thus on the final iron and steel products. In nature however, it is inevitable that iron deposits contain unwanted elements. Each element has its own distinct effect on the final steel product. The effect of high silicon is the formation of gray iron. Phosphorus mainly increases hardness and strength, lowers solidus temperature and increases fluidity and cold shortness. Finally sulphur contamination causes cracks in the iron texture when smelting and forms white iron when casting. Overall, the acceptable level of phosphorus, sulphur and silica in the iron concentrate should be less than 0.04%, 0.15 % and 1.5 % respectively.Scarcity of high grade iron ores necessitates using lower grade ores with higher amounts of impurities. The purpose of iron concentrators is to increase iron grades to an appropriate level suitable for steel making as well as removing impurities. Although many impurities can be traced in the ore, the most predominant impurities are limited to one or two elements. In this paper the beneficiation methods for removing SiO2, P and S are presented, including flotation, and the parameters that need to be considered in the design of beneficiation plants are discussed. Finally industrial cases are discussed along with their metallurgical performance.INTRODUCTIONIn metal sector, value of iron ores and concentrates is determined by iron percentage as well ascontent of:• Useful elements (Mn, Ni, Cr, V, Ti): natural alloying elements in steel• Deleterious impurities (S, P, As, Zn, Pb, K, Na): impair metal properties or complicate operational process in blast furnace• Fluxing components (Si, Ca, Mg,, Al)Sulphur and copper result in red-short, phosphorus is the cause of cold brittleness and arsenic and copper decrease welding characteristics. Sulphur should not exceed 0.15 in commercial ore. Acceptable sulphur content in ores and concentrates for producing sinter and pellets is 0.6%max, as sintering and heat hardening of pellets remove sulphur 60-90%. Phosphorous content in ores, sinter and pellets is limited to 0.07%-0.15%. 0.00.1% As max, 0.1-0.2% Zn max and up to 0.2% Cu are allowed in iron-ore part of the blast furnace burden for the production of standard conversion pig iron. Slag-forming components are divided into basic oxides (Ca, Mg) and acidic (Si, Al). Higher ratios of basic to acidic oxides are preferred since this reduces raw fluxing material."

Jan 1, 2016

By Michael Hopp

The beginning of the electroforming technology dates itself on the beginning of the industrial revolution 1800 to 1820 approximately. Basis was the existence of electricity in order to be able to drive the electro-form-process. With the development of the electroforming, big names of the science-history, like Michael Faraday (1791? 1867), Sir Humphry Davy (1778?1829), Max Schlöter (1878?1946), Werner von Siemens (1816?1892), and many others. Already about 1840, the first monograph originated to electroforming (38). While in the first years the electro-forming most extensive only to the coating of art - or other usefulness-objects was used. At the beginning of the 20th century the formation of objects from pure metals became more and more, later also from alloys to application. One of the first bigger electroforming factory, the ?Württembergische Metallwarenfabrik? was working 1894 in Geislingen / Steige, Germany. In the industrial application, the electroforming-technology is to be imagined away for miscellaneous coatingtasks and the form-body-preparation no longer today (18). A little bit confusing is the german name ?galvano-technology?. It based on the Italian physiologist and naturalist Luigi Galvani (1737 ? 1798). This technically seen is however wrong, right, the name is electroforming. The physical bases were founded mainly by Michael Faraday and Sir Humphry Davy.

Oct 1, 2003

By H. Chaouki

The aim of this work is to simulate the forming process of a green anode. For this purpose, a nonlinear compressible viscoelastic constitutive law is presented. The concept of natural reference configuration is considered. Within an isothermal thermodynamic framework, a Helmholtz free energy is proposed to take into account the nonlinear compressible deformation process occurring between natural reference configuration and current configuration. A dissipation potential is introduced in order to characterize the irreversible aspect of compaction process. Thus, the constitutive law is formulated through two equations: 1) an expression of Cauchy stress tensor and 2) a differential equation characterizing the evolution of the natural reference configuration. Material parameters are assumed to be a function of the bulk density. This allows capturing the micro-mechanical phenomena within the chosen macroscopic approach. An experimental study based on compaction tests is carried out in order to characterize the mechanical behaviour of the anode paste. A user's material VUMAT subroutine for finite element dynamic explicit analysis has been developed and implemented in the ABAQUS commercial software. To evaluate the model predictive capability, numerical simulations of the compaction forming process of anode paste were performed. Simulation results show that the constitutive law predicts the experimental trends and gives interesting physical responses. This constitutes a first step toward making a benchmark with experimental results on the forming process of anode paste.

Jan 1, 2011

By Schoeman L., K. C. Sole

Evaluation and measurement of the influence of changes in conditions and electrolyte composition during early stages of a growing metal electrodeposit are crucial to predict changes in developing morphology. A galvanodynamic polarization technique was developed to reliably measure overpotentials for nickel electrodeposition from sulfate electrolyte. The validity of these polarization parameters as indicators of the relationships between changes in the electrolyte and resulting deposit morphology was evaluated for electrolytes of varying composition. Findings indicate that nucleation and plating overpotentials measured by the described technique can be used as indicative tools for monitoring, evaluating and ultimately improving control of the electrodeposition of nickel from sulfate electrolytes. The results predict that nickel deposits of desirable quality and morphology are obtained when plating overpotentials are higher than 700 mV vs. Ag/AgCl and nucleation overpotential is less negative than plating overpotential.

Jan 1, 2017

By H. R. Shakeri, R. Mayer, M. J. Worswick, A. Rahem

The current focus of research and development in transportation industry is to use lightweight materials such as aluminium alloys for more structural components. In this regard, maintaining safety of the passenger and vehicle is the most important; therefore crashworthiness of components made of lightweight materials must be evaluated prior to sizable application of these materials. The focus of the present study is to understand failure and damage mechanisms during the axial crushing of aluminium tubes made of A1Mg3.5Mn alloy of 2 and 3.5 mm thickness. Due mainly to complexity of the crushed tubes, a microstructural approach is considered. In this study optical, stereo as well as scanning electron microscopy techniques have been used to study damage and failure mechanisms in these types of tubes, which are essential energy absorbing components in passenger vehicles.

Jan 1, 2006

By William C. Browning

An economic drilling programme is one which costs the !east in chemicals, equipment, and time. The basis for such a programme with rotary drilling techniques is a drilling fluid in which bentonites do not swell. This is recognized in the growing trend toward gyp and other inhibited mud systems. Therefore, even though the mechanism of thinner action is a subject of applied colloid ,chemistry, the understanding of this mechanism is of economic importance in controlling the flow properties of inhibited muds. In phosphate, or sodium tannate, conditioned muds that are relative-!y free of contaminating-electrolytes, the thinner, or dispersing agent, is adsor.bed, ?creating an electrical double layer about the clay particles. The mutual repulsion of these charged particles effects colloidal stabilization, or deflocculation of the suspended clays, as discussed by Norton and others. In inhibited muds, however, the electrolyte concentration in the filtrate is sufficient to collapse the double layer and flocculation of the mud solids occurs, as evidenced by increased viscosity and gel values. Chemicals to control the flow properties of inhibited muds, therefore, are vital to the successful use of these systems as it is not always economical to adjust flow properties by watering back. Flocculation of suspended particles, as indicated in the work of Vervey, Overbeek, and others, is due primarily to gravity-like, long-range Van der Waals forces. Prevention of flocculation may, therefore, be secured by the interposition of any barrier between the particles, the thickness of which approximates the extension of the Van der Waals at-traction. Organic polyelectrolytes, such as Kembreak, Rayf!o, and Q-Broxin, may act to increase the double layer charge when used in small amounts in fresh-water muds. More important, however, is the fact that in inhibited muds an increase in concentration of the polyelecholyte permits the formation of a condensed film adsorption layer of the polyelectrolyte about the clay particle. When this occurs, the extremely viscous condensed adsorption layer creates a mechanical. barrier that prevents flocculation of clays, even in the presence of inhibiting concentrations of elecholytes. Rheological evaluation of the degree of deflocculation, or colloidal stability, may be made by utilizing the known effects of particle inter-action and volume concentration on the flow properties of suspensions. Rheological evaluation should be supplemented by direct microscopic or ultra-microscopic observation.

Jan 1, 1958

By Jean-Loui Frenetie, Françoi Himbeault

"Flow of traffic in the underground mine has been improved through the years with clever use of traffic lights. The evolution is characterized by three major design changes. This paper will scan the basic criteria of these designs.IntroductionMines Gaspe, formerly known as Gaspe Copper Mines Limited, is a member of the Noranda Group of companies. The mine is the ""raison d'etre"" of the town of Murdochville, located 600 m above sea level on the Gaspe Peninsula. Paved highways link the town with Gaspe, 95 km to the east, and with Anse Pleureuse, 400 km to the north, on the Gulf of St. Lawrence.The low-grade copper mineralization was discovered in 1921 at Copper Mountain by local prospectors, the Miller brothers. Noranda Mines Limited obtained an interest in the property in 1937. World War II interrupted exploration work and it was not until 195I that a decision was made to bring the property into production.Initially, operations were confined to the Needle Mountain underground deposits which commenced production in 1955. Between 1968 and 1982, low-grade ore from the Mountain open pit supplemented the production. Due to the depressed market, surface and underground operations were suspended in 1982. Needle Mountain underground mining resumed in the second half of 1984, but the Copper Mountain open-pit operation remained idle. Since 1979, more than 75 km of exploration drilling resulted in the discovery of two new deposits, one which is located under the town of Murdochville . Mines Gaspe's present ore reserve, approximating 8 million tonnes, will be depleted by the end of 1992."

Jan 1, 1988

By E. S. Moore

GOLD was discovered previous to the year 1900 on the east shore of Emerald lake, Afton township, Timagami Forest Reserve. It was found in a small cavern in banded iron formation, close to the water's edge. This occurrence of gold was mentioned in several reports that referred briefly to this area, and prospectors evinced considerable interest in the region. It was not, however, until the Golden Rose Mining Company, which was incorporated in 1909, started operations that much work was done on the property. In 1915-16, this Company, under the direction of E. J. Townsend, the President, did a considerable amount of work. A small mill was built and ore was extracted from pits, trenches, and a one~ hundred-foot shaft. In 1927, Afton Mines, Limited, was incorporated to take over the property, and about thirty men were employed for a time. During 1934, the New Golden Rose Mining Company was organized to handle the property, and the Consolidated Mining and Smelting Company of Canada, Limited, undertook to develop the mine. In March of the following year, this Company began deepening the shaft from 100 feet to 500 feet. A considerable amount of drilling had previously been done on the hill of iron formation in which the mine is located. Further drilling was done from the surface, and altogether about twelve holes have been put down to test the formations. Over 2,000 feet of drilling has also been done from the underground workings. The mine is now known officially as the New Golden Rose mine, although to many it is better known as the Afton. To reach the property during the summer months, there is a boat trip of about thirty miles from Timagami, a wagon-road portage of one mile to Obabika lake, a boat trip of ten miles on this lake, and finally a wagon-road portage of one and one-quarter miles to Emerald lake. The mine lies about three-quarters of a mile down the east shore of the lake. A 75 h.p. Diesel engine and compressor were taken in over this' route last summer, and it is evident that the transportation problem is quite a serious one. Airplanes have been much in use, and a winter road runs from the mine to Chudleigh, on the .Canadian National railway near Sudbury.

Jan 1, 1936

By G. Vibert Douglas

"Gold occurs in Nova Scotia in three ways, saddle reefs, fissure veins, and fossil placers. Of these the saddle reefs are the commonest. They have been the source of most of the gold and have also been the subject of most of the literature on the gold occurrences.The Meguma or Gold-bearing series of Nova Scotia is a conformable succession of quartzite's and slates, possibly Precambrian in age, which have been folded into a number of anticlines and synclines that strike (Fig. 1) roughly east and west. This folding has been termed Acadian and is probably a westward continuation of the Caledonian revolution in Britain. It may have started in the Ordovician and continued through the Silurian and into the Lower Devonian. It was followed by the intrusion of the great Devonian granite batholiths. It is thought that the mineralization is connected with the late phases of the cooling of the granite. As the name saddle reef implies, the veins form on the crests and flanks of the anticlines, possibly in the synclinal troughs as well. The beds favoured by the solutions are the slates. The reason for this is apparent when it is realized that in order to fold over 30,000 feet of sediments (the thickness of the Meguma according to E. R. Faribault) through p radians of arc it is necessary to have a differential movement between the top and bottom beds of p times the thickness of the sediments. In the case of the Gold-bearing series, in which strong quartzite beds lie between incompetent slate beds, most of this differential movement was taken up in the slates. The evidence for this is the remarkably fine drag folding and the intense shearing and comminution of some of the beds of slate (Fig. 1). The quartzites exhibit some shearing and faulting, but there is little doubt that the greater permeability lay along the incompetent slate beds. The mineralizing solutions followed these beds and also passed from one slate bed to another through a joint or fault in the intervening bed of quartzite. These joining veins are called angulars in Nova Scotia. Within the veins the gold is in shoots and the real problem is to find out what controls the position and extent of the shoots."

Jan 1, 1954

By E. J. Schwarz, A. A. Winir

"Absolute magnetite contents were determined for asbestos specimens in various stages of milling by using a Faraday-type thermomagnetic balance. Comparison of these results with magnetic ratings (MR) supplied by the mining companies cooperating in this study reveals strong scatter. The main cause of this scatter is thought to be that the MR values were obtained in magnetic fields well below the saturating field of magnetite (5,000 oe). However, only the saturation moment is an intrinsic property and consequently must be used for the purpose of obtaining reliable estimates of the magnetite content. Curie points indicate that virtually pure magnetite and possibly Ni3Fe is present in all samples, and another phase, probably (Cr, Al) magnetite, is present in a few samples. The susceptibility in fields stronger than 5,000 oe is positive and falls in the normal paramagnetic range, whereas sy nthetic chrysotile exhibits weak diamagnetism. This suggests that, as a general rule, the least adulterated natural chrysotile concurs with the samples showing the smallest positive susceptibility above 5,000 oe. The magnetite appears to increase in quantity with a decrease in fibre length and to be somewhat more uniform in distribution for samples showing substantial fiberization (opening of the fibres)."

Jan 1, 1971

By V. G. Papangelakis, I. Guzman, S. J. Thorpe

Pressure oxidation (POX) leaching has been commercially applied to refractory gold ores since the 1980s. In the process, sulphide material is oxidized and dissolved in order to release the gold encapsulated in the sulphide matrix, making the gold available for further recovery. Redox potential is a significant parameter during POX, however it is only measured ex-situ at atmospheric conditions. In-situ redox potential measurement would provide instant information that allowing adjusting the process parameters accordingly. In the present study, redox potential measurements were performed during POX of sulphide material at high temperatures and high pressures. The working electrode was an Ir electrode combined with a flow-through reference electrode in a novel and robust configuration. Experiments were performed in a 2 L titanium autoclave, at 200–220°C, 50–110 psi oxygen overpressure, and 10–30% solids mass fraction. Temperature and oxygen pressure conditions were selected in order to reflect POX of refractory gold ores. Results show that the Ir electrode is consistent with theory and is able to perform well under these conditions, showing promise as a new in-situ sensor.

Jan 1, 2017

This work illustrates the potential of two welding processes for joining AA1100-16 vol.% B4C metal matrix composite: laser welding process using a 4 kW Nd:YAG laser and Friction Stir Welding. A comparison is made between these two welding techniques in terms of microstructure and mechanical properties of welded joints. A large amount of brittle needle-like phases, together with some residues of B4C particles were observed in the fusion zone of laser welded joints. The use of Ti filler can improve the microstructure and increase the joint efficiency from 63% to 75%. On the other hand, the friction stir welding process being a solid state welding technique is interesting as it avoids the formation of brittle intermetallic phases. In addition, the breakage of B4C particles and the grain refinement of the matrix were observed in the weld zone. Consequently, FSW joints show much better mechanical properties than laser welded joints. Up to 100% joint efficiency can be achieved by FSW for annealed AA1100-16 vol.% B4C materials.

Jan 1, 2011

By Z. -G. Ren, J. -S. Qian, Y. -G. Yang

The waste slags from chemical and metallurgical plants contain approximately wt 1% water soluble Cr6+. This hexavalent chromium is very harmful to human health, and the treatment of the slags has concerned metallurgists for many years. A sintering method was developed to treat the waste slag. In this process, sinter was made from a mixture of the waste slag containing hexavalent chromium, iron concentrate and coke breezes. During sintering, hexavalent chromium was reduced to trivalent chromium. The latter is known as a non-harmful material and can be used as chromium resource for the production of ferrochromium or chromium-containing cast iron. After sintering the hexavalent chromium in the sinter could be reduced to less than 0.0008%. It was found that the waste slag with fine particles was favourable to the Cr6+ removal. An increase of carbon content in the sintering mixture could increase the rate of Cr6+ removal and the strength of the sinter produced. The rate of Cr6+ removal increased with increasing basicity of the sintering materials with basicity less than B=1.8, above which it decreased with increasing basicity. Blast furnace was found to operate smoothly when using the sinter made from the waste slag containing chromium. However the productivity of sintering machine was slightly low compared to the sintering operation using ordinary raw materials.

Jan 1, 2004

By Zhan Zhang, Hiromi Nagaumi, Zhen Li

"Recently, the remarkable strengthening effect of ??-Al(Mn, Fe) Si dispersoids at both ambient temperature and elevated temperature were found by several researches. A large amount of dispersoids can be formed by applying special heat treatments and within a suitable range of chemical composition of AA3xxx alloys. In the present work, the influences of Cr addition on the mechanical properties and microstructures of the Al-Mn-Mg-Si alloys were investigated. The mechanical properties at ambient and elevated temperatures were evaluated by micro-hardness and yield strength. Moreover, the microstructures in as-cast and heat-treated conditions were quantitatively analyzed by optical and electron microscopes. Results revealed that Cr also had effect on the number density and volume fraction of dispersoids. Micro-hardness and yield strength at ambient temperature increased with the increasing content of Cr, and the Cr addition increased the yield strength at elevated temperature as well. Moreover, the creep resistance at 300°C improved dramatically with the increasing content of Cr.INTRODUCTION Traditionally, AA3xxx aluminum alloys were widely used in packaging, automobile and architecture industries, because of its good formability, excellent corrosion resistance and weldability. And AA3xxx alloys were considered as non-heat-treatable alloys. However, the strengthening effect of dispersoids in AA3xxx alloys was discovered recently (Li & Arnberg, 2003;Li, Muggerud, Olsen, & Furu, 2012; Li, Zhang, & Chen, 2016; Liu & Chen, 2015).Alarge amount of dispersoids could precipitate by a proper heat treatment.In order to further improve AA3xxxalloys, the composition of the alloys should be optimized. A few previous studies were reported to investigate the influence of compositions on AA3xxx alloys. Adding Mn element could enhance the precipitation of ??-Al(Mn, Fe)Si dispersoids and improve the yield strength(Muggerud, Mørtsell, Li, & Holmestad, 2013), as long as the concentration of Mn was under the solid solution limit. Fe decreased the solubility of Mn and accelerated the precipitation rate of ??-Al(Mn, Fe)Sidispersoids(Li & Arnberg, 2003), the yield strength and creep resistance at elevated temperature could increase with an optimized content of Fe(Liu & Chen, 2016). Mg element would affect the nucleation process of ??-Al(Mn, Fe)Sidispersoids by forming metastable Mg2Si(Hirasawa, 1975; Li, Zhang, & Chen, 2017a; Lodgaard & Ryum, 2000), metastable Mg2Si precipitated during heating process and promoted the precipitation of ??-Al(Mn, Fe)Sidispersoids, moreover, Mg provided solid solution strength for AA3004 alloys(Li et al., 2016). Si increased the volume fractionof ??-Al(Mn, Fe)Sidispersoids(Muggerud et al., 2013)and decreased the size of ??-Al(Mn, Fe)Sidispersoids(Li, Zhang, & Chen, 2017b). With the addition of Mo, the size of dispersoids became finer with a higher volume fraction, the volume percentage of dispersoid free zones was reduced. Elevated temperature yield strength and creep resistance improved due to Mo addition (Liu, Ma, & Chen, 2017).However, the effect of Crelements on microstructure and mechanical properties of AA3xxx alloys were rarely reported."

Jan 1, 2018

By Baseer Abdul, Edouard Asselin

Hydrometallurgical leaching of sulfide concentrates of copper and nickel at medium temperature (150°C) produces residues that contain sulfur and iron bearing minerals and phases. During leaching, and depending on various process parameters, iron may be precipitated as hematite, goethite, jarosite or other oxyhydroxides, which may be more or less crystalline. Hematite is the favored precipitate because it is the most environmentally stable and does not ad/absorb as much copper, nickel or other solution constituents during precipitation. However, the low solubility of iron during the medium temperature processing of sulfide ores can favour the formation of poorly crystalline, nano-scale iron oxide/oxyhydroxide phases. In some cases these phases have been positively identified as the metastable ferrihydrite, which transforms into iron oxides such as goethite, hematite and magnetite over time. A better understanding of what may help drive this transformation during leaching would ultimately result in lower valuable metal losses and more stable leach residues. Higher acid concentrations result in increased copper extractions and favor the formation of hematite during concentrate leaching, rather than other metastable phases. Furthermore, commercially available water displacement formula “WD40®” and other novel reagent(s) affect Fe precipitation and sulfur chemistry, leading to very different process outcomes such as improved extractions and larger, more easily separated, sulfur particles.

Jan 1, 2017

By N. Schreithofer, M. Aspiala, R. Serna

The novel attachment timer apparatus presented in this paper serves as a diagnostic tool that allows the detection of changes in bubble-particle attachment probability and therefore floatability caused by alterations in the chemical environment and particle properties. The apparatus consists of six identical capillaries where bubbles with defined size are produced simultaneously in a measurement chamber. The bubbles at the capillary tips are placed in contact with the submerged particle bed for specific time periods, controlled with the help of automatic actuators. The advantage of the instrument is that hundreds of bubble-particle contacts can be measured automatically within a short time period. Microscopic pictures of each measured bubble are taken while recording the movement of the bubble before, during and after contact with the solid particles. The recorded pictures can be used to determine the actual bubble size and its corresponding deviation, and to detect the attachment of particles. The attached particles are collected in a detachable chamber for subsequent characterization. Furthermore, the device is portable and can be taken to the mineral processing plants for quick evaluation of particle-bubble attachment efficiency with particles and process water sampled directly from real processes.

Jan 1, 2017

By Gary Walters, Matthew White, Thomas W. Gonzales

The copper smelting industry has transitioned into the 21st century compliant with environmental regulations, new smelter installations and brown field expansions. The industry faces new challenges as copper in concentrate grades have decreased while contained impurities have increased. A new benchmarking survey was undertaken to update the last survey of 2016 for operating copper smelters in the world. The information collected was separated based on primary smelting technology rather than by geographical location and supplemented from published literature. Each smelting technology’s unique use of specialized process equipment, concentrate smelting capacity, and impurity flexibility are discussed INTRODUCTION The 20th century was a remarkable time for the growth of copper smelting. Electric, blast and reverberator furnaces dominated the smelting technology well past WWII. In the 1970s, SO2 regulations and high energy cost drove the development of new primary smelting technology. Technological advancements decreased energy consumption and enriched sulfur dioxide concentrations of the process off-gas to levels where sulfur capture in sulfuric acid plants was economically viable. The new smelting technologies began to replace reverberatory and electric furnaces starting in the late 1940s. A new paradigm in copper smelting was established and the enabler was then Outkumpu’s® flash smelting technology from the 1940s through to today. Now, Outotec had become the dominant primary smelting technology with over 44 copper flash smelting furnace installations world-wide. Figure 1 shows the historical installation statistics of primary smelting technologies over the last 70 years (ICSG 2018). The dominance and acceptance of the Outotec® smelting technology from the 1940s to current can be seen. Isasmelt® technology for copper was introduced in the 1970s and did not see advancement in new installations until the 1990s through today. Isasmelt® has 12 world-wide copper furnace installations to date. Mitsubishi® also introduced continuous smelting and converting technology in the 1970s, but had no new installations until the 1990s with a total of 5 copper smelters. Outotec Ausmelt® smelting technology had 3 installations in the 1990s and totals 10 furnaces. Most recently the Chinese technology of Bottom Blown and Submerged Lance Smelting began commercial operations in 2005 for total installations of 11, mostly in China. Other technologies, such as, El Teniente, Noranda, Inco, and Vanyukov furnaces have contributed to the overall global smelting capacity, but have not penetrated the smelting industry to challenge the existing dominant smelting technologies. The technology distribution in Figure 1 also shows flash smelting technology for sulfide concentrate domination untill 2000, bottom blow technology has become the preference in China. Currently, China is the only country building new smelting capacity. Isasmelt® technology also seen a large increase in installations in the current decade.

Jan 1, 2019

The mechanism of thiosulfate decomposition and the products formed were investigated in the presence of pyrite or pyrrhotite in copper-ammonia solutions used for leaching gold. The presence of the sulfides significantly increased the decomposition of thiosulfate. The sulfide-surface-catalyzed oxidation of thiosulfate to tetrathionate by dissolved oxygen or the cupric tetra-ammine complex was proposed to be the dominant thiosulfate decomposition mechanism. The catalysis of the sulfides in this reaction could originate from their strong affinity for aqueous sulfur species and their semiconducting properties. Oxygen was found to be the initial driving force for thiosulfate decomposition in the absence of cupric ions and the driving force for the continuous decomposition of thiosulfate in the presence of cupric ions. Under an oxygen free atmosphere, the decomposition of thiosulfate was limited to reduce the cupric ions and the catalytic effect of the sulfides was also marginal. The dominant oxidative product of thiosulfate was trithionate in alkaline solutions especially in an oxygen rich or cupric ion rich environment. Tetrathionate was found in relatively smaller amounts in an oxygen and cupric ion deficient environment. Tetrathionate was not stable and would further decompose after extended periods. Trithionate concentrations increased almost linearly with time.

Jan 1, 2005

By J. D. Wright

This paper describes current milling practice at Endako Mines Ltd., a molybdenum producer in central British Columbia. The various steps in the crushing, grinding and flotation of the ore are outlined, with emphasis on the metallurgy of the latter operation. Tailings disposal and concentrate assaying methods are also described.

Jan 1, 1969