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By Fei Ruan, Chang Jie, Jieyu Zhang, Jifang Xu, Kuochih Chou

"Viscosity is an important physical parameter of slag in metallurgical processes. Most studies of aluminosilicate and aluminate systems assume that aluminum occurs in tetrahedral coordination. In this case, the O/Al value was utilized to describe the slag structure in terms of the network character of aluminosilicate and aluminate systems. Composition and viscosity data from the literature and the trends were analyzed according to the O/Al value and temperature. It is shown that the O/Al value explains the trends in more than ten systems, containing more than 200 data points. In aluminosilicate system, the trend that viscosity value changed with the O/Al value which implies that alumina works as network modifier such as basic oxides or works as network former. In aluminate system, irrespective of the system and temperature, viscosity decreased steadily when O/Al value increased.IntroductionMetallurgical slags, which are made of oxides and many also contain fluorides, play an important role in metallurgical processes such as iron making, steel making and secondary refining processes. Aluminosilicate slags are applied in a wide range in metallurgical processes. A polymerizing effect of the addition of aluminum and an association of aluminum with low-field strength cations is further supported by the physical variations in aluminosilicate and aluminate systems. The behavior of alumina in silicate melts has been studied by various authors [1-6]. It is generally accepted that Al2O3 is amphoteric [7] because Al3+ ions can behave in profoundly different ways in a silicate melt. When added to a pure silica melt, Al2O3 acted as a network modifier, breaking the bridging oxygen of the pure silica network, thereby decreasing the viscosity in a similar manner to other network modifiers, such as CaO, MgO etc. to form [1/2Ca (AlO4)]4- complexes. However, when added with alkali or alkali-earth metal oxides, some of the Al3+ ions assumed tetrahedral coordination and replaced Si in the liquid network, the missing charge was compensated by Me+ or Me2+ ions. Therefore Al2O3 acted as network former [8, 9]."

Jan 1, 2011

By Yong Zhao, Yan-hui Sun

Behaviors and evolutions of MgO·Al2O3 in non-oriented silicon steel during calcium treatment were investigated by thermodynamic calculations and high-temperature experiments. MgO·Al2O3 inclusions were the main type of inclusions before calcium treatment, which is also confirmed by the stability diagram of MgO/MgO·Al2O3/Al2O3 from thermodynamic calculations. After calcium treatment, the majority of original MgO·Al2O3 inclusions were mainly modified to CaO-MgO-Al2O3 system inclusions, this would be beneficial to improve castability and product quality of silicon steel. But there was no modification happening to some MgO·Al2O3 spinels which were directly surrounded by CaS inclusions. The content of Al2O3 occasionally existed a sudden increase besides a common decrease in the product layer of CaO·MgO·Al2O3. Then the evolution mechanisms of MgO·Al2O3 inclusions were proposed in present work. Thus, Al/Mg atom ratio had a significant influence on the modification of MgO·Al2O3 spinel.

Jan 1, 2016

By Zhihong Liu

Monodisperse micron size nickel oxalate particles with rhombohedron morphology were prepared from condensed Ni(OH)2 suspension by a novel gel-sol process proposed by one of the authors. Firstly, condensed nickel hydroxide gel was formed by fast adding 1 mol dm-3 NaOH solution into 0.2 mol dm-3 nickel chloride solution, and then oxalic acid solution with a concentration of 0.25 mol dm-3 was dropped into the gel drop wise through a pump equiped with a pH controller under preset pH value, and in this process, Ni(OH)2 gel was converted gradually into monodisperse nickel oxalate sol. The formation of the nickel oxalate particles was found to proceed through a dissolution-recrystallization mechanism from the nickel hydroxide gel. The product particles exhibited rhombohedron like shape with micron size long axis and sub-micron size short axis. The effects of such factors, as temperature, surfactants, et al, were evaluated experimentally on the particles sizes and morphologies.

Jan 1, 2006

By J. E. Clemson

The Black Pine sediment-hosted, disseminated gold deposit is located in Cassia County, Idaho. Gold mineralization occurs in flat-lying zones 50 to 100 feet thick. Total geological ore reserves are 5.6 million tons grading 0.049 oz/t. Ore types include: non-carbonaceous, oxidized ore; carbonaceous, sulfide ore; and carbonaceous, partly oxidized ore. In the oxidized ores, native gold grains commonly occur in porous hematite pseudomorphs that have replaced disseminated framboidal and euhedral pyrite, and this gold should be readily leached by cyanide solutions. Approximately 4 % of the native gold observed in the oxidized ores is locked within gangue and may be refractory to cyanide solutions. Native gold has not been observed in the unoxidized samples, all of which are characterized by primary sulfides. It is suspected that the bulk of the gold mineralization in the sulfide ore occurs as submicroscopic particles within pyrite and will be refractory to cyanidation. It is believed that much or all of the gold observed in the oxidized samples was originally in pyrite but was released and re-precipitated during oxidation. The degree of oxidation of the pyrite and the presence/absence of preg-robbing carbonaceous material is used as a guide in delimiting zones of mineralization amenable to heap leaching.

Jan 1, 1988

By M. C. Furerstenau

Adsorption behavior of various surfactants on sulfide minerals is very much affected by the nature of the surface of the mineral. Since sulfides are naturally meta-stable, oxidation occurs when they are exposed to air, especially in aqueous environments. As a result. oxygen assumes a major role in sulfide flotation. Mechanisms of adsorption of various thiol collectors on sulfide minerals have been reviewed. The electrochemical behavior of various sulfide minerals has also been reviewed. Flotation behavior of galena, chalcocite, sphalerite, pyrite, chalcopyrite and pentlandite has been presented together with the. flotation of copper sulfide- nickel sulfide ore.

Jan 1, 1993

By Xianwen Dai

One of the biggest challenges for the gold industry in the 21st century is the presence of copper in gold containing ore bodies. This is because copper consumes large quantities of cyanide. In addition, copper cyanide species are more stable than free cyanide, and hence are problematic in events of tailings spillage. The present paper compares cyanide and thiosulfate leaching for the recovery of gold from a copper containing ore. For cyanide leaching, the extraction of gold using copper cyanide complexes instead of free cyanide was tested in the presence and absence of added ammonia. For the thiosulfate leaching, the effect of the minerals present in the ore on the solution potential and thiosulfate consumption are illustrated.

Jan 1, 2003

By Enrique Posada

"The Valle de Aburrá area, corresponds to the city of Medellín and neighboring municipalities, with more than 3 million people. The area generates a sizable amount of solid waste, which has been taken to landfills for the last 20 years. This paper proposes a model for public policy making which considers the cost and benefit of different alternatives to handle the wastes in the coming 20 years. Combinations of several alternatives: Recycling, waste reduction, waste separation, incineration, land filling with lixiviate treating and gas energy recovery, and organic waste composting are considered and modeled and the results presented as a contribution for a more rational approach to policy making than the one currently being employed.IntroductionThe author, working for INDISA S.A., acted as a consultant for the direction of planning of the Empresas Varias de Medellín in 2004. This entity has the responsibility for the handling of the solid wastes of the city of Medellín and some of the neighboring municipalities. At the present time more the 700.000 annual tons of waste are taken to the site of La Pradera, located in very rainy location (3.000 mm of precipitation per year), with complex in topography and very far away from the sources of the waste. During the work the author detected important problems that should be addressed, as follows:Lack of adequate technical administration and resources. The entity did not count with sufficient human resources to focus on the appropriate technical handling of the solid waste. The organization worked mostly with independent contractors, lacking enough coherence and integration. The internal workload was too large for the few people who had technical responsibility and this gave rise to attention problems. It is important to have clear technical procedures, technical know how and human resources, continuity in the activities. It is important to have a clear capacity to plan, to study, to make tests and monitoring, to pursuit and develop ideas, to optimize the processes and to introduce changes, to respond to environmental authorities, to the communities and to mass media and to handle the contractors. All this was basically lacking. In the case of the handling of the sanitary filling of La Pradera, for example, although the people in charge were very able and dedicated, the magnitude of the task was too large and the resources they had were insufficient. As a result, the site had at the time of the study, problems with thousands of vultures, lack of immediate cover up for the waste, uncontrolled leaching, the area being dirty and little attractive, despite being called a park."

Jan 1, 2008

By Yotamu Stephen Rainford Hara

"The aim of our work is to investigate a low energy and clean route for the recovery of copper and cobalt from complex sulphide mineral concentrates. The mineral concentrates were roasted in air, in the presence of CaO (MS + CaO + 202 =MO+ CaS04) at temperatures below 973K. The roasted products containing CuO, CoO and Fe203 were carbothermically reduced at 1073K within an hour to preferentially reduce copper and cobalt. The kinetics of reactions were studied using the thermogravimetric technique and by characterisation ofreaction products using the XRDSEM-EDX techniques. The effects of MS:CaO ratio, roasting temperatures and physical nature of the mineral concentrates were analysed. The method for capturing S02 by forming CaS04 was analysed for reuse in the process. The energy balance for the above process is compared with that of conventional continuous smelting/converting process.1.0 IntroductionCopper sulphide mineral concentrates from Zambia contains substantial amouot of cobalt. The cobalt metal content in the concentrates ranges between 0.7 and 2 % weight, which corresponds to 3 and 9 % weight copper, based on the spot price of copper ($7 386/tone) and cobalt ($31 000/tone). Although the traditional approach using a combination of roasting-leaching-electrowining steps can be applied to recover copper and cobalt from sulphide mineral concentrates [1-4], there are two major draw backs of the traditional process: (i) the S02 emitted during roasting is too lean for economical conversion for sulphuric acid manufacture, which causes serious environmental pollution. (ii) silver and gold which are normally present in the sulphide concentrates are lost out [5] because they are not leachable by H2S04 or HCl which are the common leachants. The above two problems have been overcome by adopting flash smelting in which a rich S02 gas above 20% is produced [1, 5] and successfully converted into sulphuric acid. The precious metals tend to partition to blister copper and recovered during refming. However, nearly all cobalt is lost into the slag phase uoder oxidising condition which prevails during flash smelting. It is important to note that the cobalt content in the slag can be up to 2.6 % weight [6]. The recovery of cobalt from the slag is a process which requires huge amouot of energy since the slag is smelted above 1873K [6]. With a view of minimising the amouot of energy and S02 emission during metal recovery, our investigation involves roasting the sulphide concentrates in the presence of lime and reducing the roasted samples with carbon."

Jan 1, 2013

By Larry G. Stolarczyk

The development of geosteering technology for geothermal reservoirs is challenged by the integration of electrically small antennas in small-diameter metallic drill rods. To be useful, the antenna pattern must achieve sufficient back-lobe suppression, preferably with a forward-looking pattern. Forward-looking capability requires an antenna array with phase control. The phase-controlled antenna pattern enables imaging of geologic structures ahead of and surrounding the well bore. This paper describes the development of electric and magnetic dipole arrays for small-diameter drilling pipe.

Jan 1, 2006

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 M. Pineau, G. A. Monteith, M. Laliberte, G. Houlachi

Conventional physico-chemical treatment methods, either hydroxide or sulfide precipitation, can hardly achieve a high removal of selenium from the liquid effluents which can be generated in some metallurgical operations. In weak acid solutions, selenium exists mainly as anionic species (selenite Se03-2 and selenate SeCV2) which, therefore, cannot precipitate as metal hydroxide or metal sulfide compounds. At the same time, neither selenite nor selenate form stable precipitates with the common cations (Ca, Mg, Fe, etc.) that are typically used in water treatment. At Noranda Inc., CEZinc Division in Valleyfield, Canada, the introduction of new discharge requirements for effluent toxicity initiated a R&D program which resulted in the full-scale implementation of a new treatment method for selenium removal. The goal of this paper is to present this new method which is now being patented by CEZinc. The process chemistry will be presented along with pilot-scale developments and full-scale operational results.

Jan 1, 2000

By Liu Chunpeng

The new technological process developed is by means of thermal plasma arc smelting to obtain high grade Ni matte directly from Ni-Cu concentrates containing 6-7% nickel and 3-8% sulfur. In comparising with conventional smelting and converting processes the plasma arc smelting process has many advantages over conventional processes, such as lower energy consumption, lower capital investment and free from SO, pollution by transforming the sulfides into elemental sulfur with microwave irradiation under controlled oxygen potential, moreover, the process is simple and easily controlled due to less magnetite troubles in the operation. Therefore, this new technological process can be used as an alternative way to conventional process for Ni-Cu concentrate smelting. The main economical technical index is summarized in Tabal 1. Table 1 Main Ecnomic-technical Index

Jan 1, 1993

By M. A. H. Shuva, M. A. Rhamdhani, G. A. Brooks, S. H. Masood, M. A. Reuter

Ferrous-calcium-silicate (FCS) based slag has been used in the copper industry over the last two decades. The FCS slag has also been used in a secondary copper processing such as in black copper smelting which has different operation conditions compared to that of typical primary copper processing. In the process, a variety of copper bearing scraps from sources such as industrial waste, consumer waste and electronic waste (e-waste) are used. The valuable metals in these sec- ondary resources are distributed in different phases during the process. Understanding the behaviour of the valuable elements at the relevant conditions is vital for optimizing the process and to maximize the recovery of the elements. In this study, we investigated the structure of Ge-containing FCS-based slag at different conditions (oxygen partial pressure and temperature) using Fourier-Transform Infrared (FTIR) spectroscopy to explore the effect of the polymerization on the behaviour of the valuable element Ge in the slag. It was found that experimental parameters significantly in fluence the slag structure, and therefore, the partitioning of Ge in the slag. A correlation between the distribution ratio of Ge and the slag structure has developed in the current study.

Mar 1, 2018

By K. B. Dotson

A common international safety and health management system was developed. Analysis of selected major safety and health management systems from around the world was conducted. Functional elements of selected systems were grouped to identify common elements and key differences. Common elements were subjected to qualitative judgments of equivalency and then reconciled. With few exceptions, differing elements were revised to achieve cultural neutrality. The resulting 98 system elements were organized according to the NOSA numbering and title scheme. System summaries were produced in Spanish and English. A pre-implementation self-assessment evaluated conformance in three distinct cultures. The consensus 98 element system was internally named the BHP Copper Five Star Safety System Performance Management Guidelines. Development of a common system within an organization with international operations can enhance the ability of the staff function to share resources, programs and subsystem improvements and thereby increasingly protect workers. Common systems can increase the level of management support by demonstrating increased compatibility of the safety and health management function with traditional business objectives. Safety professionals, industrial and occupational hygienists, business managers and the safety and health of workers will benefit from further development and articulation of common systems for safety and health management.

Jan 1, 1999

By S. S. Chabot, S. E. James

A recent survey of major steel companies worldwide revealed the importance of recycling zinc units from electric arc furnace (EAF) dust, mill scale, blast furnace dust and other zinc containing streams within the steel industry. Many processes have been developed and installed in response to this challenge. The most successful approach involves the production of a crude zinc oxide and its sale to primary zinc producers to recover the metal values. The problem with this process is the high concentration of halides in the crude oxide. This type of material cannot be processed directly in an electrolytic zinc plant because of the corrosion problems it will cause in electrolysis. In 1999, Big River Zinc installed a zinc oxide receiving and washing plant to minimize the impact of halides in its electrolysis circuit. A description of the washing plant and the initial operating results are presented in this paper.

Jan 1, 2000

By K. A. Elbarawy

Processing of Egyptian barite ore with a composition of 85.5% BaSO4; 2.75%SiO2;1.56%Fe2O3 and 5.1% Al2O3 was performed with the aim to prepare pure barium salts. The process took place through pelletization-solid state reduction and leaching steps. Each of these steps was optimized. Pure barium sulphate (99% < 0.82µm) and carbonate (99%<0.75µm )were the final products. This article deals with the reduction process that occur whn coal was added to the ore during pelletization in the ratio of 5:1 stoichiometry. Optimum reduction of pellets of 8-12mm in diameter was achieved after 60 minutes at 1050oC and under a rate of 5 lmin-1 of nitrogen atmosphere, where 87.79% of the ore was reduced. The kinetic studies showed that the reduction process could be modeled according to the core mechanism of diffusion control in which the effective diffusivity is based on the surface area of unreacted ore. The activation energy calculated was 92.7 kJmol-1.

Jan 1, 2006

By L. Cifuentes

Electrodialysis (ED), i.e. a technique based on the effects of electrically charged membranes on ions in solution in an electric field, has been applied to Cu-Fe-As-Sb- H2SO4 electrolytes similar to those used in copper electrorefining and electrowinning operations. The effects of current density, time and species concentration have been studied in a batch ED cell. The technique has shown to be effective in concentrating and separating a range of ions and points to possible new methods of treating copper electrometallurgy effluents.

Jan 1, 1999

By A. F. Otero

During the electrowinning (EW) of copper significant quantities of highly toxic vapors (acid mist) are produced due to the liberation of oxygen at the cathodes. Acid mist affects the health of operators, the environment and plant infrastructure. Acid mist can be decreased to acceptable levels by a combination of physical means (e.g. ventilation, plastic spheres over electrolyte) and chemical surfactants that decrease the surface tension of the electrolyte, modifying the way oxygen bubbles burst at the surface of the electrolyte. However, only few chemical surfactants are compatible with electrolytic applications, and they are not always used due to their high costs. This paper describes the application of a novel surfactant of natural origin (commercial name Mistop®) to suppress acid mist in copper EW process. Mistop® contains triterpenic saponins derived from the Chilean quillaja tree Quillaja saponaria Molina. The product is non-toxic, and poses no risks to the environment or to EW operators. Mistop® was tested at a laboratory, pilot plant and industrial scale in the world?s largest copper EW production plant at Radomiro Tomic (RT), CODELCO, Chile. At a Mistop® dosage of 8-9 ppm, acid mist decreased below the value accepted by Chilean regulations (< 0.5 mg/m3). At this dosage, Mistop® represents and economical alternative to chemical surfactants, and it is currently industrially used at RT.

Jan 1, 2003

By Florian Kongoli

Converters have been playing an important role in the extraction and processing of metals ever since the first type of converter was invented about 100 years ago. Historically their operation has been mainly based on the experience of talented operators rather than on strict control and optimization technologies. However, in the new realities of unavoidable necessity to increase productivity and in the conditions of diversification of primary materials from various geographical areas, improving control and optimization techniques have become indispensable. In this paper a review of the authors? previous work in terms of improving control and optimization of converter operational practices related to magnetite content and precipitation, slag and metal blows, problematic and dangerous elements such as As, Sb etc. has been described by highlighting the advantages that the new control and optimization methods and tools bring to everyday converter practices. Several examples are given and future work is underlined

Jan 1, 2005

By Kimura. E.

Continuous estimation of phosphorus content of molten copper is required to produce phosphorus deoxidized copper in a continuous casting operation. The phosphorus content of molten copper was related to its electric resistivity, which was measured by the four-probed technique with a specially-shaped cell. In a laboratory scale, the linear relationship between the above factors was confirmed in the temperature range of 1083OC through 1200°C. The phosphorus concentration range measured was from 40 to 500 ppm. The phosphorus content was monitored successfully by measuring the electric resistivity of the molten copper in the distributor of a continuous caster in an industrial scale.

Jan 1, 1992