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By Alvear G. R. F. Flores

It is now 35 years since the organization of the first sulfide smelting conference in 1983. Since then, the smelting base metals industry has experienced several changes driven by the necessity to improve economic, operational and environmental performances and resource efficiency and meet the increasing market demand for metals. In this continuously challenging environment, it is relevant to recognize which are the main challenges that the industry will face in the coming years and critically address our preparedness to respond to them. This analysis have to consider not only the effort required from the fundamental research and technology aspects but also how these pillars interact with the drivers behind the base metals industry. This paper discusses some relevant aspects required to continue developing the base metal industry focusing on copper. Aspects such as the need to supporting the generation of fundamental metallurgical knowledge, acquisition and proper use of data with advanced analytics methods, technological innovation to develop sustainable process flowsheet are discussed with emphasis on efforts conducted by Aurubis.

By Rina Kim

The addition of lead to a gold leaching reactor can effectively accelerate or retard the gold cyanidation reaction. This study explored the effect of lead on the gold dissolution kinetics using cyclic voltammetry (CV) experiments. It was illustrated that the gold leaching kinetics in the cyanide solution enhanced with the addition of lead salt in the low overpotential region (–0.35 V vs. Ag/AgCl). The similar behavior was observed in the presence of ore containing 0.25% galena. In contrast, the gold oxidation kinetics retarded at –0.35 V (vs. Ag/AgCl) in the presence of silicate and lead-bearing mineral under certain conditions. Likewise, the lead addition was not functional for the high sulfur ore. This was attributed to the oxidation of the sulfides to the elemental sulfur, which subsequently formed a passivating layer on the gold surface. The results were evidently affirmed by the electrochemical tests and X-ray photoelectron spectroscopy (XPS) analysis.

By David Melgaard

A significant emerging recycling, waste minimization problem stems from legacy waste from the nuclear weapons program and from production of power using nuclear fuel. Premium quality metals used in nuclear plants become contaminated, making them unsuitable for reuse. Consequently, decontamination studies were conducted to evaluate the decontamination capacity and partitioning effeetiveness of Electroslag Remelting (ESR). Eight laboratory melts were conducted to evaluate the efficacy of using ESR to transport radionuclides from the liquid metal phase to the liquid flux or slag phase. To determine the decontamination effectiveness, several surrogate compounds for uranium, plutonium and other fission products were added to the melts. During the melts, the melting rate was varied, typical slag additives were used, and two different slag compositions were evaluated. The resultant post-test ingots and slag were then analyzed to determine the partitioning of the surrogates. ESR generally proved very effective in removing contaminates from the metal with a few noted exceptions. -

Jan 1, 2003

By Florian Kongoli

The behavior of cobalt as a by-product in the NilCu smelting and converting processes effects directly the quality of the final products as well as the revenues gained from the overall process. An effective way to evaluate and predict this important behavior is thermodynamic modeling which reduces the time and the cost of experimental investigation. In this work a thermodynamic model of cobalt-containing matte phase in NilCu smelting and converting processes is presented. The model predicts a priori the thermodynamic properties and phase relations of the ternary and multicomponent matte based solely upon the optimized parameters of the binary systems. This model can be used with other models such as those of slag, metal, gas etc. to predict various aspects of cobalt behavior such as matte- slag, metal-slag distribution, etc.

Jan 1, 1999

By Ikuhiro Sumi

A new steelmaking process, in which manganese ore was intentionally reduced, was developed to achieve a higher manganese Yield using a combined blowing converter. In this study, manganese behavior was discussed through the introduction of a model. Apparent reduction rates of manganese were calculated by the two terms that were determined experimentally, with SOkg and 2S0ton combined blowing converters. The model calculated manganese changes during the operation. We applied the model to the actual operation and found that manganese behavior was predicted fairly well by this model.

Jan 1, 1996

By L. Petitnicolas

The experimental study of nitrogen absorption and its removal from a liquid Ni-20%Cr alloy at 1873 K has been undertaken, using an experimental, apparatus based on the Sieverts technique in order to determine the solubility of nitrogen in the alloy. as well as the kinetics of nitrogen transfer across the gas/melt interface. Experiments show that nitrogen solute equilibrium content can be calculated using the Sievens law. Measurements point out the nitrogen absorption reaction rate to be well described by first order kinetics, whereas experiments on nitrogen removal reveal that the rate is better expressed using a second order equation.

Jan 1, 1996

By I. Peerawattuk

Growing demand for Li-based battery technologies is leading to an unprecedented growth in the lithium industry. Although innovation in battery technologies has pushed lithium into the spotlight, lithium was not always known for its application in batteries. The primary use of lithium—prior to the introduction of commercial lithium-ion batteries in the early 2000s—was in the ceramics, glass, grease, and the medical industry. Before being converted into usable forms, lithium products must be upgraded from the raw material. Processes for recovering lithium may involve: thermal treatment, water leaching, solar evaporation, ion exchange, carbonation, and electrodialysis. Presented, is a historical review of lithium applications and the different techniques of converting lithium-rich minerals and brines into usable products with additional discussion on future lithium extraction processes.

By W. G. Davenport

Chapter 1 showed that flash smelting is a key step in extracting copper from sulfide ores. It also showed that there , are two versions of flash smelting: (a) Outokumpu flash smelting, which uses oxygen-enriched air blast and injects dry feed downwards into a hot furnace (b) lncoflash? smelting, which uses industrial oxygen blast and injects dry feed horizontally into a hot furnace. This chapter describes Outokumpu flash smelting.

Jan 1, 2001

By G. Van Weert, A. van Sandwijk, O. W. J. S. Rutten

"Cathodic and anodic reactions in an acidic nitrate medium were studied in reference to the production of electrolytic manganese dioxide from pyrolusite' (Mn02) ores by reductive leaching. Two USA ores were investigated. The reductant for the pyrolusite ore is produced cathodically in an electrolytic cell and can either be nitrous acid (HN02) or nitric oxide gas (NO). In this work emphasis was placed on the nitrous acid leach. In a high-temperature leach in a nitrous/nitric acid medium, manganese and silver are solubilized and iron is not. Anodic electrowinning of manganese dioxide from the acidic manganese nitrate electrolyte yields flaky y-Mn02, similar to that produced from sulfate and chloride electrolytes. Cathodic regeneration of nitrorts acid was studied in a membrane cell in 1.0 M nitric acid and 0.0 to 0.1 M nitrous acid on a' platinized titanium cathode. At cathode potentials ranging from +950 to +700 mV (SHE), cathodic reduction to nitrous acid takes place, at cathode potentials < +700 mV, cathodic reduction of nitrous acid to nitric oxide takes place. A conceptual process is presented and discussed.IntroductionManganiferous-silver oresLarge reserves of manganiferous-silver ores are present in the Southwestern United States and Latin America. These ores are generally refractory to hydrometallurgical methods of treatment, due to the insolubility of the higher oxides of manganese (Mn 4+) in all common lixiviants such as cyanide solutions, dilute sulfuric acid, nitric acid, ammonia, salt solution, thiosulfates, etc. The silver is either bound by the insoluble manganese, or is rendered inaccessible to cyanide leach solution by the surrounding manganese mineralization.Higher oxides of manganese will dissolve if they are first reduced pyrometallurgically to manganous oxide (Mn2+). This is a widely used pretreatment for manganese dioxide ores and subsequent dissolution in sulfuric acid is common. In order to avoid the pyrometallurgical pretreatment with its large energy requirements and gaseous emissions, fully hydrometallurgical processes have been proposed. These processes are based on the presence of a reductant in solution, in order to reduce the insoluble higher oxides of manganese to soluble lower oxides. Aqueous S02 has been proposed and tested on industrial scale by the U.S. Bureau of Mines. After washing, silver could be extracted by cyanidation. The neutralization of the pulp prior to cyanidation however causes problems in filtration and the reagent consumptions are high [1]. More recently, acidified thiourea and bacteria were proposed for the solubilization of both manganese and silver in a single leach step. High extractions were obtained, but drawbacks of these methods are high reagent consumption or slow kinetics [2,3]. For the options of manganese recovery from the leach filtrate, precipitation with persulfate or ammonium carbonate and ion exchange have been proposed. The proposed options for silver reclaim are precipitation with either zinc or Na2S and adsorption onto activated carbon."

Jan 1, 1997

By Zhucheng Huang, Lingyun Yi, Bin Chai, Tao Jiang

"A high iron content manganese ore was reduced at 900~1200°C and followed by a magnetic separation process. SEM and EDS analyzes were employed to examine the transformation of microstructure and phase in reduced sample and the mechanism was revealed. Results showed that elements enriched during reduction. Iron existed in the metal iron phase and most of oxygen formed compound with manganese. Consequently a clear distinguish between iron phase and manganese minerals formed, which was beneficial to the separation of iron and manganese. But the iron phase can not be monomer dissociation in grinding process and manganese compounds turned into magnetic product as package and mechanic inclusion due to the isomorphism of iron and manganese and the small particle size. And MnO could be found partially in iron phase, which hindered the further separation of manganese and iron.IntroductionManganese is widely used in industry. The amount of manganese used in steel industry is very huge and 90% manganese is used in steel industry. Manganese ore resources are rich in China, yet with fewer rich ore but more low-grade ore which accounts for 93.6% and fine refractory ore. The constitution of the ore is very complex and more than 73% of all the manganese ore contains iron[l,2]. With the increasing of consumption of steel, the demand for manganese is becoming larger and larger and the imported ore accounts for more than 50%. Therefore, how to use the manganese ore efficiently has very significant meaning. The main method is manganese residual, which is simple and stable. However, the development of the method is limited by the quality of manganese ore, the huge amount of manganese residual, the technology of blast furnace process and economics[3,4]. Chemical benefication which may pollute environment and is difficult to recover iron is still being researched[5,6]. The paper investigated the process in which anthracite coal was the reducing agent for coal-based direct reduction and magnetic separation of the ore, and SEM with EDS measurements were employed to examine the transformation of phase in reduced sample and the mechanism was revealed[7,8]."

Jan 1, 2013

By H. Jiang, S. Yang

"The main processes for nickel metallurgy in China consist of electric arc furnace smelting to produce low grade nickel matte and converter to high grade nickel matte, grinding and flotation to separate nickel sulfide from copper sulfide and direct electrolysis of nickel matte. Systematic studies on the properties of electric furnace slag, smelting process for nickel matte, anodic process of nickel matte, cathodic process of nickel electrolysis have been done in our labs. In addition, an approach to a new hydrometallurgy process for nickel matte has been done. The feature of the new process is one stage acidic leaching of high grade nickel matte. The leaching solution could be purified by deposition way or by solvent extraction way. There are two leaching rate-determing steps, chemistry reaction-determing one at temperatures below 600C and diffusion-determing one at temperatures higher than 600 c. The acidic leaching fraction reacted dvaties with leaching time t according to the equation 1-(1- a ) 1/3=kt. The experimental data also show that the leaching reaction rate varies with concentrations of H+, Cl-, and it is also effected by copper sulfide and Cu++. The Cu++ ion can retard the leaching reaction due to forming a copper sulfide layer on the matte surface and the equation 1- 2/3 a. - (1- a: ) 2/3 akt can be used for the case. However the copper sulfide added into nickel matte can facilitate the leaching process. The research work for nickel metallurgy done by others in China has also been mentioned in this paper.Large scale production of nickel in China started in 1960s.The main processes consist of electric arc furnace smelting to produce low grade nickel matte and converter to high grade nickel matte grinding and floatation to separate copper sulfide from nickel sulfide and direct electrolysis of nickel matte.To reduce nickel loss in slag a reseaech group organized by Jinchuan Company and Central South Institute of Mining and Metallurgy (now the Central South University of Technology) measured the viscosity surface tention density conductance melting point and structure of the slag(I).lt has been found that the physico-chemical properties of the slag depend on the components SiO2 ,MgO and FeO but FeO in the slag is too high and the statistic analysis of data from industry gave an equation to correlate the content of Ni in slag with the content of Ni in matte and the composition of slag again it was pointed out that the content of FeO in slag effected the loss of Ni in slag very much (2). The ratio (FeO+MgO) to SiO2shouid be less than 1.13 and the content of Fe3O4should be as low as possible but the reaction"

Jan 1, 1988

By Rina Kim

There are many factors which affect the gold cyanidation mechanism— mineral composition, free cyanide and dissolved oxygen (DO) concentrations, heavy metal additions, etc. This study combines electrochemistry and surface analysis methods to examine the effectiveness of the above factors on gold cyanidation process. Three gold ore samples were used in this study. Sample 1 was a pyrite concentrate, contained mercury and silver. Sample 2 also contained sulfide minerals, including galena. Sample 3 contained pyrite with sphalerite and galena. In the case of samples 1 and 2, the presence of heavy metals enhanced gold cyanidation kinetics, though the addition of higher DO was not effective on improving the kinetics. Sample 3 showed an opposite behavior: the kinetics was not enhanced by galena, because of its relatively small amount, however, the use of higher DO made improvement in the gold leaching kinetics, likely caused by iron species generated by pyrite oxidation.

By O. Norman Lotter

There are many scales of innovation in the pursuit of concentrator performance improvement, including paradigm change, inventive change and incremental change. All are important, but the last is low risk, low cost and has a relatively high probability of success, given the right metallurgical skills. Seeking continuous improvement is also essential to ensure that performance does not decline over time due to ore type changes, personnel changes, equipment wear and other factors. When properly implemented, these small gains offer a very high rate of return for the project cost because they are made from marginal, not total, operating costs of the plant. To be effective this approach requires plant trials that use designed structure and appropriate statistics to test the observed differences arising from the old and new process treatments, be they a change in flotation reagent, in grind, pulp density, etc. However the pursuit of small but financially significant performance gains is often regarded as fruitless because of the range of variance in plant data, and the consequent difficulty of ‘proving’ that a benefit has been achieved. Opportunity for improvement is thus sometimes relegated to the realm of the impossible, or at best, treated with skepticism. Operations managers prefer to look for the larger gains, which are easier to demonstrate and prove. Unfortunately, these are seldom to be found; rather, a large gain can be more easily made by executing a series of small recovery improvements that are together equivalent to the ephemeral single large gain. In this paper we advocate a policy of continuing improvement driven by rigorous performance testing protocols and a formal ‘risk analysis’ approach to judging the efficacy of changes implemented in the plant. Following these simple procedures allows rational decisions to be made on the basis of quantifying risk and reward. In particular we consider the choice of hurdle rate for decision-making which best balances risk and reward. It is shown through case studies from actual industrial practice that this approach is practical and delivers significant financial value to the operation.

By Patrick R. Taylor

A non-transferred arc thermal plasma assisted cyclone reactor has been designed, built and operated to evaluate its use in vitrification of wastes. Simulated waste (liquid, slurry or fine particulate) is injected near the plasma flame, where nearly instantaneous dehydration and calcination reactions happen. A non-transferred arc plasma torch was attached tangentially to the cyclone and is utilized as both an enthalpy source and to provide the gas velocities required to generate the cyclonic gas flow patterns. The closed top cyclone flow sends the solid particulates to the wall, where they are captured by a thin film of molten glass that is injected as a powder at a position lower in the reactor. The molten glass is then collected in a crucible. The feasibility of simulant injection directly into the flame zone and its effect on electrode lifetimes has been studied. Several candidate refractory systems have been evaluated for their suitability for extended use under the demanding conditions present in the cyclone reactor.

Jan 1, 2002

By John W. Ahlrichs

Microscope, electron microprobe and x-ray diffraction have been used to provide quantitative evaluation of products from the mill, smelter, refinery and other metallurgical processes. Phase compositions and their quantities are necessary for an adequate understanding of the various products obtained throughout an operation and in laboratory testing. By careful evaluation, important information can be gained in improving recoveries and increasing grades at various stages of processing. Four case histories are discussed in this paper. Quantitative microscopic counting techniques are applied to mill products to determine degrees of locking and liberation of the economic minerals. Rapid, but accurate evaluation aids the metallurgist to develop or improve the grinding and flotation circuits. In the smelter, the identification and quantification of the phases are important for predicting reaction mechanisms and kinetic trends. Mineralogic techniques have been applied to conventional smelter products, and to those obtained in laboratory tests for newly developed innovations to smelting. Small, but important, values of gold occurrences in ore are difficult to determine. Evaluation of gold usually requires special separations into various mineral concentrates, followed by assays and mineralogic determinations of the products. Numerous occurrences of solid solution constituents can be treated as by-products, but often they are deleterious to metallurgical treatment. Most solid solution problems can be unraveled by the mineralogist&apos;s tools.

Jan 1, 1981

By N. B. Gray, A. E. Guerra, D. E. Morton

"The formation of splash in pyrometallurgical operations that involve the injection of gases into a liquid has been the subject of a number of studies over the last few decades. Given the complexity of the phenomena, there have been some advances in understanding the microscale formation of splash but the ability to accurately predict the amount and character of the splash formed is still in its infancy. First, the macroscale mechanisms for splash formation is very varied. Second, the timescales for splash formation are very small, usually less than 100 milliseconds, making experiments elucidating the formation of splash difficult and costly. Work at the GKW CRC has shown that the microscale mechanism of splash formation is primarily is due to the Kelvin-Helmholtz instability. Substantial progress has been made in understanding the behaviour of large bubbles in effecting splash formation and a simple model has been developed to estimate the behaviour of splash formed from a top submerged lance. Direct numerical computation of splash formation using the GKMAC codes developed at the Centre has been successful in simulating the impact of liquid drops onto a liquid bath.IntroductionInjection of gases into melts is used in the metallurgical industry to promote mixing to ensure acceptable heat and mass transfer rates, conveying solids for alloying, provide efficient contact for gas-melt reactions, and as a reactant. High gas injection rates bring about the formation of splash and slop. Extensive splash formation leads to loss of valuable product, creation of safety hazards, formation of accretion on refractory lining and exhaust ducts, and increased load on dust removal equipment. Many operators and researchers have claimed that splash formation is the limiting factor in many gas injected processes. The problems listed above lead to loss of production and increased maintenance, adding to the cost of processing base metals. Over the last five years, the GKW CRC has been studying the formation of splash from a number of sources. They include the impingment of drops on liquids[ l·2.31, slopping of bath liquidI4.51, breakup of gas bubbles at the liquid-gas interfacel61, shearing of liquids by gases[7·81, and impact of packets of fluids on solidsl81. Theoretically, the extreme deformation of fluid shape and the influence of surface tension makes the simulation of flow resulting from only a drop impacting on a liquid surface a very challenging computational fluid dynamics problem. Recently, we have been successful in simulating the formation of the Rayleigh jet resulting from a drop impact showing the effect of drop Froude number on the shape of the Rayleigh jet."

Jan 1, 1996

By Dominik Hofer

A broad spectrum of tantalum containing input materials can be processed for the production of synthetic tantalum concentrate (“SynCon”). The use of these low grade substances offers a secure alternative to mining of coltan in Central Africa. SynCon is produced in a multi-stage pyrometallurgical process, wherefore the melting behaviour of slags presents an important factor especially regarding the energy consumption and its optimisation. The characteristics of a slag comprising mostly Al2O3, CaO, SiO2 and MgO are influenced by the amount of other oxidic constituents which enfolds the main focus of this study. A hot stage microscope serves for the investigation of the slag behaviour in a temperature range from 1000 to 1600 °C under reducing atmosphere (CO/CO2 gas). The experimental results are compared with thermodynamic calculations (FactSage) to get a better understanding of the process.

By Z. Zhang, R. G. Reddy

The viscosities of industrial lead slags with various compositions were measured as a function of temperature. It was found that viscosities of lead slags decreased with increasing temperature, and the plots of ln(11) vs. 104tr followed a linear relation over the reported ranges of temperature. Using the data of this study and available other related data from the literature, a viscosity expression was developed as a function of composition and temperature. The calculated results using this viscosity expression are in good agreement with the measured data. The composition dependency of viscosity of lead slags is discussed.

Jan 1, 2000

By Vladimiros G. Papangelakis

During the past five years, chemical modelling work at the University of Toronto has elucidated the role of soluble magnesium on the autoclave acidity and has demonstrated why feeds rich in magnesium, and other divalent metals, require more than the stoichiometric requirements in acid to produce a leaching performance comparable to that of low magnesium feeds. This understanding has allowed the calculation of acid additions to the pressure acid leach (PAL) on a less empirical basis. Optimizing acid additions to the PAL confers savings in neutralization costs, ensures high productivity and minimises corrosion problems. Hence, our picture of the solution chemistry inside the autoclave during the PAL process has been substantially improved and is reviewed here. Experimental techniques based on solubility and direct acidity measurements that support the theoretical predictions are presented. Concepts of chemical modelling of electrolyte systems at high temperature and software issues are also discussed. Finally, a better understanding of the solution chemistry at temperature has led to better kinetics models because all metal dissolution and precipitation reactions are acid driven and controlled. . Therefore, reactor modelling efforts by our group are also presented and a reactor model with very good performance, as compared to pilot-plant data, is also made here. Finally, in spite of the above success in PAL solution chemistry and reactor modelling, significant challenges lie ahead in theoretical data gaps and instrumentation; these are also discussed in this paper. Keywords: Laterites, process modelling, pressure acid leach, solution chemistry, chemical modelling, reactor simulation

Jan 1, 2004

By Gabriel Riveros

The stags from the Teniente Converter (TC) have high copper and magnetite contents. The reduction and copper impoverishment of these slags in an electric furnace was simulated in the laboratory, as part of a conceptual study for the Ventanas smelter of ENAMI. The effect of power input, electrode immersion, temperature of the slag, coke and solid revert additions on the rate of magnetite reduction and copper recovery was investigated. It was found that the addition of solid reverts, containing copper matte, enhanced the recovery of copper. Magnetite stratification and a corresponding gradient of the copper content occurred in the slag. Microscopic examination of slag samples showed the presence of copper in the form of matte and metallic copper inclusions. The results of the experimental work combined with an analysis of the phenomena that take place in an electric furnace led to a better understanding of the slag cleaning mechanism. The successful start-up of the slag cleaning electric furnace at the Ventanas smelter resulted in good copper recovery and confirmed the beneficial effect of solid reverts addition. Electrode consumption is lower than anticipated. No bottom build-up problems have been experienced. Keywords: copper, slag, magnetite.

Jan 1, 2001