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By Gustavo E. Lagos

Mining is one of the oldest and most important productive activities in Chile. In the latter half of the 80's &d during the 1990's Chilean mining has experienced explosive growth fundamentally due to legislative changes which have encouraged an influx of foreign capital. Fine copper production has grown from 1,4 million tons in 1987 to 3,4 million tons in 1997. Gold production has increased from 17.03 tons in 1987 to 49.46 tons in 1997. In both cases private investment has driven this growth. The direct impact of mining on the Chilean economy has been considered one of the fundamental pillars of the growth of the country in the last years. The indirect impact that has generated on the other sectors of the Chilean economy and in particular the regional economies, has not been analyzed. This paper outlines a methodology for estimating the impact of mining investment and mining operations in different sectors of the Chilean economy at both regional and national levels. It applies this methodology to the case of Minera Escondida, the largest copper mine in the world, analyzing its economic impacts on the regional and national levels.

Jan 1, 1999

By V. A. Bryukvin

It has been found that by superimposing symmetric alternating current over the process, the rate of nickel and cobalt leaching from metallized products with copper sulfate solutions increases by a factor of 1.5 to 2.0 and the apparent activation energy of the process investigated is reduced from 12 down to 6.6 kcal/mole. It appears especially attractive to use alternating current for anodic dissolution (oxidation) of metallic scrap of refractory metals and their alloys in ammonia electrolytes permits production of high-grade commercial products in the form of respective ammonium salts using a short and virtually reagent-free process flowsheet. Similar approaches can be applied also for electrochemical processing of nickel and copper scrap in sulfuric acid media with subsequent recovery of pure sulfate salts or electrolytic processing. Electrochemical technology for recycling of tungsten-cobalt (WC 15) and tungsten-rhenium (WR 20) alloys has been also investigated. In the former case, anodic oxidation of carbide alloy was carried out in nitric acid electrolyte with production of pure tungstic acid. The research conducted has indicated that the physicochemical effect of alternating current results in a lower activation energy of electrode reactions due to changes in the mechanisms of the electrode reactions themselves.

Jan 1, 2006

By Oleg I. Platonov

Method of high-temperature reduction of oxygen-bearing sulfurous gas has been developed at Copper Plant (CP) of MMC ?Norilsk Nickel? Trans-Polar Division (PD) with the aim of producing elemental sulfur from Vanyukov furnace? off-gas. Non-explosive reduction technology of oxygen-bearing sulfurous gas by methane utilized at Copper Plant has been designed to separate the processes of gas heating and sulfur dioxide reduction based on different kinetic of the reactions oxygen fixing and SO2 reduction. First, natural gas promptly reacts with oxygen contained in the process gas to heat a gas mixture up to the temperature of sulfur dioxide reduction (1200C). Then isothermal reduction takes place within 1 sec. Combustion chamber (pre-chamber) design developed based on the above principles is presented. Practical experience of the two reduction reactors operation at CP since 1996 proves high efficiency of the developed reduction process. The volume efficiency rises dramatically thanks to the fact that both fuel and reducing agent are fed into the reactor volume in the form of high-speed turbulent jets providing an intensive mixing of the reacting gases. On condition of equal internal volume of the reactors, the developed process offers higher efficiency of reagent interaction resulting in sulfur conversion exceeding 90%, as compared to the equilibrium one.

Jan 1, 2006

By Yoshio Waseda

A laser flash method has been applied to obtain the thermal diffusivity values of Zr55Al10Ni5Cu30 alloy in the liquid, glassy, crystallized and supercooled liquid states. The electrical resistivity of this particular alloy was measured in the glassy, and crystallized states by a direct current four probe technique. A specific heat of Zr55Al10Ni5Cu30 alloy was also determined by a differential scanning calorimeter in the glassy state. On the other hand, thermal diffusivity values for two alloys of Zr60Al15Ni25 and Zr65Al7.5Cu27.5 were measured in the crystallized and liquid states. The thermal diffusivity values of three Zr-based alloys in the liquid state are summarized in the linear equations with positive temperature dependency and it is noted that the lower the thermal diffusivity values of Zr-based alloys at liquidus temperature, the lower the critical cooling rate to obtain metallic glass phase becomes. The thermal diffusivity values of Zr-based alloys were compared with those of Pd-based alloy case. These results suggest that thermal diffusivity of alloy liquids might be an indicator of the glass-forming ability of Zr-based and Pd-based alloys.

Jan 1, 2006

By F. Guevara

The paper presents results of physical and turbulent three-dimensional numerical simulation of the gas flow in the wind box and reaction shaft of the concentrate burner of a flash furnace. Physical simulation work was carried out in a 1:5 linear scale model, where the velocity field was measured using a Pitot tube. The mathematical model consists of the three-dimensional averaged Navier-Stokes equations, turbulent kinetic energy and dissipation of turbulent kinetic energy using the Renormalization Group (RNG) theory for the k-e turbulence model. Computations were performed using FLUENT, based in a finite- volume code. The geometry of the concentrate burner was separated in two sections: wind box and reaction tower. Results obtained at the exit of the wind box were used as boundary conditions for the reaction shaft. The effect of boundary conditions on the numerical results was also studied. Results of physical and numerical simulations show an asymmetry of the velocity field at the exit of wind box. This asymmetry is possibly due to existence of a separated flow in the back of the exit ring. The agreement of physical and numerical results assess the capacity of the turbulence RNG k-e model to reproduce correctly the behaviour of the velocity field at the exit of the concentrate burner.

Jan 1, 1999

By John Hollow

The Fort Knox Mine is an open-pit operation, located in Alaska, which started commercial production in March 1997. A conventional Mill processes 38,000 tpd of a low grade (1.0 g/t Au) free milling gold ore with a low sulphide component (below 1%). Gold production (11% from gravity and 89% from cyanidation) exceeds 400,000 ounces per year. Short retention time (20h), low temperature (7oC) and low grade make high leaching kinetics critical for the performance of the process. In April 2001, the treatment of True North ore, which represented 14.4% of the mill throughput and contained more sulphide in the form of pyrite, arsenopyrite and stibnite, resulted in a substantial drop in the average gold extraction from 87% to 72.6%. Laboratory investigations indicated that the addition of lead nitrate increased gold extraction to 91.7%. Further investigations were initiated to determine the leaching parameters and the nature of the problem. Subsequently, a lead nitrate addition scheme was implemented at the Fort Knox Mill that resulted in 2002 gold production being in excess of 31,000 ounces higher than that estimated for the non-lead nitrate reagent scheme. This paper presents the results of laboratory investigations and modifications in plant operating practices.

Jan 1, 2003

By H. Singh, Anupam Agrawal, H. S. Grewal

"Erosion in industrial appliances causes huge loss of valuable resources especially when solid particles are present in the working medium. A number of erosion models that are available in the literature claimed to predict the erosion response. In this work, five erosion models have been evaluated using computational fluid dynamics (CFD) methodology. Three most commonly used experimental test rigs (solid particle and unsubmerged slurry jet type and pot type) have been simulated and comparisons with the experimental results have been performed. The study helps in understanding the effect of fluid medium and flow pattern on the erosion process. The knowledge acquired shows that phenomenological based erosion models give better results considering the wide range of operating parameters. The in-depth study of the flow field shows the possibility that erosion mechanism, being parameter dependent, could change with location on the same specimen.1.0 IntroductionErosion is a surface degradation phenomenon which causes the removal of material due to impacts either of solid particles and/or bubbles or gas entrained in a fluid medium. Erosion has various categories depending upon the erosion medium such as, solid particles erosion (solid particles entrained in gaseous medium), slurry erosion (solid particles entrained in liquid medium) or cavitation erosion (erosion caused by exploding gas or vapor bubbles). Humphrey [1] has listed 21 different factors that decide the erosion response of the components under a given working condition. The number of factors involved in the erosion process gives us an idea about its complex nature."

Jan 1, 2012

By Bo Yan, Jiaquan Zhang, Haibo Sun

"Based on the validation of steady-state isothermal mathematical model by a 0.4-scale water model for the single-strand slab casting tundish, the effect of varying pouring temperature on the flow, temperature field, and residence time distribution(RTD) of the liquid steel was studied by a transient hydrodynamic model. Due to the decreasing temperature of ladle stream over a casting period of 50 min, the direction of vortex flow at the downstream side of dam changes to clockwise from the anticlockwise at 4 min after the new teeming, and reverts to anticlockwise direction again at 43 min. Meanwhile, the melt flow state in the dam hole is also varying with time. For conventional isothermal water modeling, the RTD parameters obtained are much different as compared with the non-isothermal ones. For the flow control devices(FCD) design, however, the identical optimal scheme can be concluded from the point of view of isothermal modeling.IntroductionOriginally, tundish was adopted as a buffer and distributor to hold and allocate molten steel for sequence casting upon ladle exchange and to provide a desired steel flow rate to the mould below. With the increasing demand to strand quality, the tundish has become a critical metallurgical reactor to enhance inclusions removal, avoid reoxidation of molten steel, and prevent slag entrapment. The general trends to obtain these metallurgical effects are to optimize steel flow pattern and to extend the residence time of molten steel in the tundish through increasing the volume of tundish and/or using FCDs in the interior of the tundish."

Jan 1, 2012

By Wenjie Zhu

Hexavalent chromium is a widespread environmental contaminant. An Achromobacter sp. strain nominated Ch1 can reduce soluble and toxic chromate to insoluble and non toxic Cr(III) in aerobic cultures, and no Cr(VI) decrease was observed in anaerobic cultures. In contrast with other Cr(VI) reducing microorganisms, Ch1 showed higher Cr(VI) reduction at high pH. Reduction performed under alkaline conditions at pH 7 to 11, and the optimal pH was 10. During the reduction, pH decrease was observed may caused by production of acidic metabolic byproducts from aerobic respiration. In the present study, the ability of Achromobacter sp. Ch1 to reduce Cr(VI) during growth was evaluated with lactate as an electron donor. In NB medium, Ch1 reduced 100% of 24mM of Cr(VI) in 35h, but only 73% of 30mM of Cr(VI) after 48h of inoculation. Reduction was inhibited by metal ions like Ag+, Cu2+, Zn2+, slightly inhibited by Mn2+, and not affected by Mg2+. Results revealed that reduction rate of Cr(VI) also increased with the increasing of concentrations of lactate, and complete reduction was achieved at the concentrations above 40 mM. HPLC analysis demonstrated Cr(VI) reduction was associated with the consumption of lactate. There was a large quantity of dark blue sediment generated in the culture during Cr(VI) reduction by Ch1. Energy dispersive X-ray (EDX) analysis showed that the major element composed the formed sediment was chromium presented as Cr(OH)3 precipitate. The features characterizing Cr(VI) reduction by Achromobacter sp. Ch1 are high Cr(VI) concentrations and high pH.

Jan 1, 2006

By Bora Derin, Onuralp Yucel, M. Seref Sonmez, Murat Alkan

"Latest stage in the production of boron carbide by metallothermic methods using magnesium was the leaching process. Boron carbide particles obtained by self-propagating high temperature synthesis contained several impurities such as magnesium oxide and magnesium borates after the metallothermic reactions. Removal of such contaminates by hydrometallurgical methods required to produce high purity boron carbide. Leaching by concentrated hydrochloric acid solutions resulted in the production of pure boron carbide together with high magnesium and boron containing solutions. Removal of such ions from the spent liquor was the necessity to have dischargeable solution. In this study, precipitation of magnesium and boron compounds from relevant chloride containing spent liquors and the production of saleable products was aimed. The effects of chemical reagents, pH of the solution on the precipitation efficiency of magnesium and boron compounds were investigated in the study. Chemical analysis and the characterisationof solid phases by using x-ray diffraction analysis were the latest stage.Introduction A variety of advanced ceramics, inter-metallic, organic and inorganic compounds, oxygen free single crystals, and polymers can be synthesized by using different SHS techniques [1, 2, 3]. In the SHS process, after initiation, reaction becomes self-sustaining and propagates in the reactant mixture. A high amount of heat which is generated during the process accelerates the reaction rate and thus it makes the process highly productive and economically feasible for different production scales. After the SHS process obtained powder mixture needs to reacted with acidic solutions to purify the product. In this case B2O3 was reacted together with C and Mg to synthesis fine B4C powder resulted in the production of MgO as well according to the Eq. 1 and then MgO was removed from the mixture by leaching with the concentrated HCl solution as shown in Eq. 2, respectively [4, 5]."

Jan 1, 2008

By M. Brian Maple

A rich variety of phenomena are produced by superconducting-magnetic interactions in rare earth and actinide compounds. These phenomena, and the materials in. which they have been observed, are described in this talk, with an emphasis on the new high superconducting transition temperature (Tc) copper oxides. The Materials The-materials in which these phenomena occur can' be divided into two classes. In the first group, there are two distinct interpenetrating systems of electrons, a set of localized 4f or 5f electrons and a set of itinerant electrons. The localized f electrons carry magnetic moments and interact with the spins and momenta of the the itinerant electrons, which are involved in the superconductivity, via exchange and electromagnetic interactions; respectively. This category includes materials containing rare earth (R) and actinide elements with partially-filled f electron shells which have been inroduced as substitutional impurities [e.g., La1-xCexA12, Th1-xUx] or form a sublattice in compounds [e.g., RRh4B4, RMo6S8, RMo6Se8, the high Tc. superconductors RBa2Cu3O7-d(d - 0.05)]. Materials of the second type are characterized by a single band of electrons that is responsible for both superconductivity and magnetic order. This group includes heavy electron rare earth and actinide compounds [e.g., CeCu2Si2, UBe13, UPt3, URu2Si2], and the high Tc copper oxide superconductors such as the hole-doped systems Lag- MxCuO4 (M = Ca, Sr, Ba, Na) and RBa2Cu3O7-d(0 =d= 1) and the electron-dope system Ln2-xMxCuO4-y (Ln = Pr, Nd, Sm, Eu; M = Ce, Th; x = 0.15; y - 0.02).

Jan 1, 1992

By Dale T. Peters

In the United States, the United Kingdom and numerous other countries, copper has long been the plumbing material of choice. This has been the case since the late 1920s in the United States and since World War II in the United Kingdom. However, in recent years the plumbing tube market has caught the eye of the chemical industry, and several plastic resins have been introduced to the marketplace as substitutes for copper in household plumbing systems. One of these, polybutylene tube, had so many failures in the United States that a class action law suit was filed, and the manufactures of this product were forced to create a trust fund of nearly one billion dollars to repair damages caused by their product. Chlorinated polyvinylchloride (CPVC), in rigid pipe form, on the other hand, has been mechanically acceptable albeit its recent introduction precludes the test of time enjoyed by copper tube in this application. This paper reviews the State of California's portrayal of copper's environmental effects and will be largely based on the data and information assembled by the Copper Development Association Inc. in its presentation to the State of California in August, 1998 in response to the State's Draft Environmental Impact Report for Chlorinated Polyvinyl Chloride (CVPC) Pipe for Use for Potable Water Piping in Residential Buildings. The paper is intended for use as a model for the use of other copper organizations and individuals in responding to similar situations.

Jan 1, 1999

By A. V. Tarasov

Regeneration of carbide waste from hard-alloy (sintered carbide) manufacture is an important scientific and technical objective aimed at improving the degree of recycling of rare metals (W, Co, Ta, Ti, Nb). Currently, the degree of recycling of those metals does not exceed 25% to 35% of their total production even in industrially developed countries. This is attributed to a significant extent to the substantial drawbacks of the technologies applied for their processing (environmental pollution, limitations to the use of regenerated products for important applications, sophisticated equipment to be used). An innovative environmentally sound technology has been developed in the Institute of Metallurgy of the Russian Academy of Sciences (IMET RAN) for processing of carbide waste of WC, TiC, TTC and other carbides using asymmetric alternating current of industrial frequency (the electrolyte used for this purpose is nitric acid solution). The current efficiency under optimal conditions is as high as 96% to 98%. The process has been tested on bench scale. The following commercial-grade products are obtained: pure ammonium paratungstate, tungstic acid, cobalt oxide, titanium dioxide and tantalum-niobium concentrate. The total metals recovery is 98% to 99%.

Jan 1, 2006

By Akram Salah Eddine Belaidi, Lakhdar Azzouz, Benchaa Benabed

"The dunes sand is a material of a large availability in Algeria. This material is practically unexploited. The introduction of this material as a new element in the construction can be more relieve the domain of building, and contribute to the development of the southern regions of Algeria, which are very rich in this material. The main objective of our work is to exploit a largely available material in the Algerian south which is the dunes sand, as a material of construction in the region of Laghouat.In this study, first we investigated the effect of the curing environment and the nature of the sand on the mechanical properties of the mortar, such as; flexural and compressive strengths. Then after, we studied the durability of the mortar under cycles of wettingdrying and the chemical attack of sodium sulfate (Na2SO4 5%).According to the results, we note that the mortar of the sand mixes (river sand plus dunes sand) present the best mechanical performances under different environment of curing. In addition result of durability studies put forward that the mortar of the sand mixes is more resistant to the sulfates attack."

Jan 1, 2008

By Guodong Lai, Shixing Wang, Lijuan Chu, Jinhui Peng, Zebiao Zhang

"The beneficiation of poor manganese ores containing phosphate gangue is very difficult by conventional processes, because of the similarities in the physico-chemical properties of the constituent minerals. The shaking table gravity concentration process and concentrated strong acid selective intensified leaching process were used for dephosphorisation of Yunnan manganese ore. The leaching process was effective. The effects of intensified leaching time, solid-liquid ratio and particle size were investigated. The relevant leaching factors were optimized as -0.125+0.088 mm particle size with 68% nitric acid for 24 h when using a solid-liquid ratio of 1:1 at room temperature and atmospheric pressure. Under these conditions, the P/Mn ratio was reduced from 0.0107 to 0.0056, and the grade of manganese was increased from 12.32% to 42.76%. The dissolution of manganese during leaching was negligible.IntroductionManganese and its compounds are widely used in the iron and steel industry as deoxidation and desulfurization agents and as alloying additives [1-2]. Because of the increase in demand, low grade refractory manganese ores are becoming a new source. Many Chinese manganese ores are high in phosphorus, which cannot be used directly for metallurgical purposes. This occurs because phosphorus enters into the metal phase during smelting and its presence sharply deteriorates the mechanical properties of the metal [3-4].Kanungo and Sant [3] investigated the dephosphorization of phosphorus-rich manganese ores by selective leaching with dilute hydrochloric acid. They observed that leaching with dilute hydrochloric acid (0.1-0.6M) could reduce the phosphorus contents to the specified limit of 0.12%. Ye [5] investigated dephosphorization of high-phosphorus manganese ore of the Huayuan type. Using high intensity magnetic separation, roasting and leaching with acid for dephosphorization, as used in the industry, a 40.15% manganese concentrate with a P/Mn ratio of 0.0037 was obtained. Yimin [6] investigated magnetic separation followed by inverse flotation of high-phosphorus manganese ore, and found that the P/Mn ratio could be reduced from 0.046 to 0.002."

Jan 1, 2012

By Bob Drew, Alfred Spanring, Kirschen. Marcus

"Increasing material conversion and energy efficiency, and decreasing carbon dioxide emission levels are crucial for sustainable production processes in the aluminum, cooper, and steel industries. RHI supports these targets by providing a diverse range of solutions including high quality refractory linings, optimum lining maintenance, and process improvements. In this paper examples are provided of process improvements and increased energy efficiency in copper refining, potential energy savings during electric arc furnace and ladle operations in the steel industry, and increased energy efficiency by improved heat transfer in anode baking furnaces in the aluminum industry. In all cases, RHI’s expertise in close collaboration with the customer resulted in an improved performance of the reactor lining and the actual high temperature process with a positive impact on the material conversion and energy efficiency and as a result a decrease in specific carbon dioxide emission levels.IntroductionRefractory linings play an important role in heat transfer during high temperature processes in for example the aluminum, copper, and steel production industries. Due to constantly increasing energy prices worldwide and the increasing demands for environmental and climate protection, improving the energy efficiency and decreasing emission levels of these energy intensive production processes is of significant importance. In this paper, the contribution of modern RHI lining technologies to energy saving measures and the corresponding reduction of specific carbon dioxide emission are described. The type of current refractory solutions for energy intense processes are illustrated with four examples: Optimization and increase of material conversion and energy efficiency in copper refining, energy saving potentials in both electric arc furnace and transport ladle operations in the steel industry, and heat transfer improvements during the carbon anode annealing process in the aluminum industry. These examples focus on particular production processes operating with a high proportion of recycled copper, steel, and carbon anodes. Increased energy efficiency directly decreases the specific energy related carbon emission levels whereas improvements to the metallurgical processes aim to increase material conversion efficiency and, therefore, decrease specific process related carbon emission levels. Significant energy savings can be achieved by maximizing the refractory campaign length through a combination of appropriate refractory material selection, grade zoning, correct installation, careful preheating, and effective maintenance strategies. Besides the efforts to improve the performance and energy efficiency of customer high temperature processes, RHI continuously promotes the development of new low emission carbon-containing refractory bricks and unshaped products."

Jan 1, 2008

By Pedro Lobarinhas

In the present work a two dimensional computational model is derived for the description of the time dependent heap leaching process. The flow inside the heap is calculated using the diffusion equations for the flow in porous media. The soil conductivity is also estimated assuming a close packed structure for the grain packing inside the heap. These equations, with appropriate boundary conditions, are solved using a time step splitting scheme. From this calculation the amount of leaching reagent in contact with the ore at any position inside the heap can be calculated and, once coupled with appropriate reaction equations, the amount of metals extracted can be computed and leaching agent concentration updated. The model is tested with available experimental data and the results have shown to be in a very good agreement. The model predicts all the transient features of the data.

Jan 1, 1999

By Jiangtao Li, Zhongwei Zhao, Xingyu Chen, Xuheng Liu

The method of ultrasonic-assisted leaching was used to extract vanadium from the stone coal, with alkali as leaching reagent. The effects of ultrasonic power, concentration of alkali, reaction temperature, liquid-solid ratio and reaction time were investigated, respectively. The optimal ultrasonic leaching condition for vanadium extraction is as follows: ultrasonic power 230W, concentration of alkali 5%, liquid-solid ratio 3:1, reaction temperature 90℃ and reaction time 1h. The leaching rate of vanadium reaches 76.4% under the optimal condition, which is 12.2% higher than that of non-ultrasonic leaching. The reason on enhancing the leaching rate of vanadium by ultrasonic leaching was discussed. It is indicated that the ultrasonic cavitation can increase the surface area of mineral, which is beneficial to facilitate the reaction rate. Keywords: stone coal; vanadium; alkaline leaching; ultrasonic

Jan 1, 2014

By Kurt Westerlund

Three years operating experience of the FLUXFLOW waste heat boiler (WHB) 20.000 nm3/0h at Boliden Rönnskär Sweden on a TBRC smelting galena (PbS). Operating experience from the Kivset flash WHB 11.900 nm3/h at Samim, Porto Vesme, Sardinia, Italy. Conceptual features of the 93.600 nm3/h FLUXFLOW (WHB) on the Isasmelt smelting in melt furnace for 180.000 t Cu/a at Mount Isa, Australia.

Jan 1, 1992

By A. Kar, J. Mazumder

"Inherent rapid cooling in laser processing often produces novel materials due to nonequilibrium partitioning during solidification. This paper reports theoretical and experimental investigations on in situ alloy formation with extended solid solution.A mathematical model for determining the composition of metastable alloys and the effects of various process parameters on the composition of extended solid solution is presented. To model the nonequilibrium partitioning of solute in concentrated solution, rate equations and conservation of mass equations are used and an expression for nonequilibrium partition coefficients is derived for concentrated solution, which is realistic for laser alloying and cladding. Effect of rapid cooling on solute segregation is presented by deriving an expression for nonequilibrium partition coefficient.Experiments were performed with Ni-AI and Ni-Hf systems to obtain the composition of solute in the extended solid solution produced during laser cladding."

Jan 1, 1988