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By Jeffrey W. Braithwaite

The laboratory characterization of the oxidation of chalcopyrite under conditions of deep solution mining is presented in this paper. A salient feature of this system is the pH buffering effect resulting from simultaneous acid producing and acid consuming oxidation reactions. The solution chemistry and related sulfur partitioning of the oxidation reactions are detailed. The contribution of temperature, acid concentration, oxygen pressure, particle size, and solution additions to the kinetics of copper extraction are presented. A mixed kinetic model was used to describe the kinetics of oxidation.

Jan 1, 1976

By T. Inami

The chlorine leach of the anode slime was studied in order to improve the treatment process at the Niihama Nickel Refinery. The anode slime originates from the nickel matte electrorefining and, contains 3-5% of nickel as sulfides. A comparative study has been conducted on the filter cake resulting from the sulfur filtration of the molten anode slime. The kinetic factors of the chlorine leach such as temperature, grain size were defined. Under the optimized condition, 70-80% of the nickel is recovered from the slime or filter cake. On the basis of these results, the chlorine leach process for the treatment of anode slime has been established. The leaching plant has been installed and successfully operated since 1986.

Jan 1, 1988

By I-Min Lu

An electric field was applied to a metal-bearing kaolinite specimen to investigate the efficiency of electro-osmosis in removing heavy metals from contaminated soils. The electric field induces a flow of water through the porous medium, called electro-osmosis, which is superimposed on the hydraulic flow. Because the electro-osmotic flow is relatively stronger in smaller pores, it can enhance the displacement of contaminated solution by fluid convection. Furthermore local changes in pH caused by the electrode reactions can affect adsorption equilibria and the distribution of solutes between the solution and the solid surfaces. The electro-osmosis experiments were conducted by applying either a constant current or a constant voltage across 8-cm inside diameter, 25 to 30-cm long specimens of kaolinite clay with graphite electrodes. Samples of the pore fluid and of the clay were analyzed to determine metal content, pH, and conductivity as functions of time and position. Results show that removal of heavy metals from soil can be accomplished effectively by electrokinetic treatment of sufficient duration. Approximately 95% of the lead was removed after 189 days.

Jan 1, 1996

By Tatsuzo Kitamura

The tank house of Tamano refinery, that started its operation in January, 1972, was constructed incorporating the application of Periodic Reverse Current (P.R.C.) from the outset of design works. In 1973, the production of electrolytic copper came up to 8,000 mtpm, a sharp increase ds compared with the designed capacity of 7,000 mtpm, and successful operation has been achieved up to the present. P.R.C. has been employed for the purpose of raising productivity level and reducing copper inventories. Since there were various problems in P.R.C. application to such a large sized cathode as 1 m x 1 m, special attentions were paid to the following items: -Development of a unique bus bar to make an electrolytic current to each electrode as uniform as possible. -Improvement of circulating method of electrolyte. -Application of high-performance equipment to realize a uniform spacing between anode and cathode. Owing to these creative technical developments mentioned above, technical level for operation up to 350 amp per sq m of cathode current density has been established. The quality of electrolytic copper, which was a matter of interest, has been proved to be as excellent as those of conventional electrolysis products through a long term supply to the field of SCR and Dip forming where high levels in quality are required.

Jan 1, 1976

By S. J. Buckler

Many chemical and metallurgical processes use submerged gas injection to increase contact area between gas and liquid phases in order to promote faster overall reaction or refining rates. The total interfacial area produced by gas injection through lances, nozzles or tuyeres is both an important design parameter for new vessels and a measurement for estimating the maximum processing capacity of existing equipment. Estimating total interfacial area from submerged injection into industrial pyrometallurgical vessels from existing knowledge is a problem with two aspects. The first difficulty is the difference in behaviour of cold (aqueous) and hot (molten metal) systems, implying that existing models and correlations of gas-liquid behaviour developed in low temperature systems are not necessarily appropriate for estimation of high temperature behaviour. The second difficulty is the issue of scale-up of correlations from laboratory to industrial sized vessels. The work presented in this paper is part of an ongoing experimental investigation, at the GK Williams CRC for Extractive Metallurgy, to quantify the total gas-liquid interfacial area available in pyrometallurgical vessels using chemical measurement methods. The effects of three operating variables, injected gas flow rate, nozzle diameter and nozzle submergence, on total interfacial area are quantified in a IOOL aqueous system - the first stage of a three stage process in examining the implications for scale-up of high temperature, medium-scale results are discussed. The results of work at high, injected gas flow rates (up to 500/min) show that the submerged Froude number is not sufficient for use as the sole variable in a predictive model of total interfacial area. Further work is being undertaken to identify other dimensionless variables that will better represent the gas-liquid characteristics in submerged injection that influence the formation of total interfacial area. The second and third stages of the experimental investigation involve measuring the total interfacial area in a large-scale (1000L) aqueous sodium sulphite and small-medium scale molten metal baths.

Jan 1, 2002

By Adam Powell, Soobhankar Pati

"Solid Oxide Membrane (SOM) Electrolysis is a new energy-efficient zero-emissions process for producing high-purity magnesium and high-purity oxygen directly from industrial-grade MgO. SOM Recycling combines SOM electrolysis with electrorefining, continuously and efficiently producing high-purity magnesium from low-purity partially oxidized scrap. In both processes, electrolysis and/or electrorefining take place in the crucible, where raw material is continuously fed into the molten salt electrolyte, producing magnesium vapor at the cathode and oxygen at the inert anode inside the SOM. This paper describes a three-dimensional multi-physics finite-element model of ionic current, fluid flow driven by argon bubbling and thermal buoyancy, and heat and mass transport in the crucible. The model predicts the effects of stirring on the anode boundary layer and its time scale of formation, and the effect of natural convection at the outer wall. MOxST has developed this model as a tool for scale-up design of these closely-related processes.IntroductionSolid Oxide Membrane (SOM) Electrolysis is a variation on the Hall-Héroult process for molten salt electrolysis of oxides which promises to solve many of the problems of its predecessors. Magnesium in particular is both soluble in molten salts and highly reactive, such that it migrates to the anode and reacts with the oxygen or C02 anode product, reducing current efficiency to as low as 10-20%. But a zirconia solid electrolyte between the molten salt and anode blocks this reaction, boosting current efficiency to at least 90%. Separating the anode from the molten salt also opens up anode material selection to liquid metals and SOFC cathode materials such as Lai.xSrxMn03 (LSM) and YCr03. And zirconia's selectivity makes the oxygen by-product very pure."

Jan 1, 2012

By Sylvain Gouttebroze, Mohammed M'Hamdi

In a previous work, a small scale Bridgman furnace has been used to study silicon bi-grain crystallization at different cooling rate. This work expands the analysis by studying the mechanical interaction between the crucible and ingot during the solidification and cooling. The thermal model is based on a 2D-axisymetric heat-transfer model. The flux histories are then transferred to the ingot-crucible 3D-model. Anisotropic Elastic and Crystal Plasticity model are used to model the silicon deformation. Four different assumptions are applied to model the mechanical contact crucible-ingot and three grain misorientations are considered. The results show the strong impact of the alumina crucible contraction on the stresses and deformations in the silicon ingot.

Jan 1, 2015

By Takashi Ikeda, Masafumi Maeda

"Demand for solar cells is increasing linearly throughout the world. Last year production totaled 3000 tons worldwide. The market size of solar silicon is expected to increase further because of international ""political"" demand to reduce carbonaceous emission from energy consumed. Most elemental silicon is produced by the carbon reduction of Silica in an electric arc furnace. Purity of silicon at this stage is 90-99%. Major impurities are Fe, Ti, Ca· and Al, and minor ones are P, B and carbon. The oxidizing metallurgical process is no longer effective to remove transitfon metals because those are less noble to silicon. Nonmetallic impurities such as phosphorus and boron must be reduced to 0.001ppm for semiconductor use. The most common process for high purity silicon is the Siemens C process, which is basically distillation of hydro-chlorinated silicon followed by CVD of SiHCl3. The cost of such silicon is expensive to allow its popular use in solar cells. Currently scrap silicon -of semiconductors is used for this; however, the supply-of that scrap is limited to just a portion of semiconductor production.In this paper world demand for silicon will be reviewed and some of the processes proposed summarized.IntroductionSilicon is element 14 in atomic number and has an atomic weight of 28.0855. Little elemental silicon is found in the earth, and it is mostly found as oxides or silicate. The Clark number of silicon is very large and the second in its number. If we were discussing the volatility of silicon element on the globe, we would never worry about it. However, it is very difficult to obtain pure elemental silicon because a high purity silicon compound is very rare. In most cases these are silica (silicon oxide SiO2). As shown in Table 1, there are many grades of silica ore classified mainly by their content of iron and alumina."

Jan 1, 2000

By Luis M. González, Guzmánm Guillermo D., Davis Juan C.

"The Teniente converter (CT) of the Ventanas Smelter and Refinery of Codelco-Chile has two tuyeres for dry concentrate injection directly into the melt.The diluted phase injection system can feed 15 to 20 kg of concentrate for 1 kg of air, which creates a very abrasive solid/gas phase. The tuyeres commonly used lasted for about 3.5 days due to the accelerated decay of the shell, and 1.5 hours were necessary for the replacement of new ones in the reactor.Tests were carried out with common shell tuyeres with a tungsten based welding cover, and a life span of 28 days was reached, increasing the Teniente converter operational continuity between 1.5 to 2 %."

Jan 1, 2009

A novel, low-pressure adaptation of Praxair?s coherent jet technology utilizing CoJet lances was developed for application at Inco&apos;s Copper Cliff Smelter where oxygen is available in large tonnage quantities but only at relatively low supply pressures (< 193 kPa header pressure). The project objectives were to evaluate the effect of coherent jet technology on controlling oxygen lance accretion (?horn?) formation and to increase oxygen efficiency in the Inco Oxygen Top-Blowing Nitrogen Bottom Stirring (TBBS) MK Reactor used for converting nickel- contaminated chalcocite to semi-blister copper. This paper describes the development and subsequent implementation and testing of two CoJet lances in this application.

Jan 1, 2005

By Jose Bengoa

Low metal prices and environmental restrictions are always a challenge for copper smelters operation and its productivity. Thus, in order to reduce production costs and control gas emissions, improvements of the Teniente Converter (CT) operation were made at 110 Smelter Plant of Southern Peru Copper Co" 110, Peru, and the main objective was to increase its capacity for smelting copper concentrates without affecting normal operation, The present work eorresponds to a recent study conducted during the normal industrial operation of the Teniente Converter in this plant and, it shows the effect of increasing air oxygen enrichment from 28 to 34% on its productivity. The results show an increasing of concentrate smelting rate from 800 to 1370 tpd and hence a notorious improving in copper production, and practically no effect on the refractory consumption. The increment of the concentrate throughput, increases also the SO2 concentration and the sulfuric acid production, showing the effort done by this operation in order to accomplish the environmental Peruvian regulation,

Jan 1, 2003

By Tejs Vegge

The lack of suitable means of storing hydrogen for use in the transport sector is generally viewed as a primary showstopper for a hydrogen economy. Recent developments within solid state hydrogen storage in complex hydrides and metal ammines have sparked new hope of a long term solution, but as of now, no materials fulfill all the DoE targets for onboard storage [1]. A detailed physical understanding of the ab-/desorption processes and the role of the essential catalytic additives is an essential prerequisite for the development of new optimized hydrogen storage systems. Here, we illustrate the potential of utilizing the synergy of combining state-of-the-art in theoretical methods and experimental techniques in the analysis and design of materials for hydrogen storage. Recent advances in computer hard- and software has made it possible to treat many of the essential problems in such materials, i.e. structural stability, hydrogen dissociation and diffusion, with high accuracy methods like density functional theory. We rely on such results to guide our synthesis of new materials, and to interpret our experimental results from, e.g. time dependant in situ x-ray diffraction, synchrotron/neutron experiments, and advanced materials testing. Through a continuous feed-back optimization loop between theory and experiments, the obtained nano-scale insight is used to expedite the design and development of novel materials for hydrogen storage.

Jan 1, 2006

By Chen-Ming Kuo, Esher Hsu

"The importers and manufacturers who import or produce products with packaging containers are charged a recycling fee in Taiwan. The amount of waste packaging containers used for calculating the recycling charge is based upon the amount declared by importers and manufacturers which might be underestimated. This study aims to estimate the amount of waste packaging containers generated by households in Taiwan and also explores its distribution. The sampling survey and ratio estimation are conducted for estimating the recycled amount; while the refuse sampling method for municipal solid waste composition is employed to estimate the un-recycled waste packaging containers. The estimated total amount of waste packaging containers in 2011 generated by households in Taiwan is 696,511 m.t., of which, 79.49% of the waste packaging containers were recycled and 20.51 % were landfilled or incinerated. This study shows that the amount of waste packaging containers declared by importers and producers is underestimated around 20%.IntroductionWaste packaging containers including iron cans, aluminum cans, glass bottles, plastic containers, paper containers, aluminum foiled paper packs are officially announced to be recycled in Taiwan. In order to create the economic incentive for raising recycling performance, associated manufacturers and importers are charged a recycling fee to subsidize recyclers. The amount of packaging containers declared by importers and manufacturers is used for calculating the recycling charge and recycling rate. The importers and manufacturers might underreport their producing (importing) amount to pay less recycling fees. Therefore, the estimated waste packaging containers based upon the amount declared by importers and manufacturers is usually underestimated. Related previous studies about waste packaging containers recycling in Taiwan are done by Hsu and co-workers [1-4]. Hsu and Kuo [1] estimated total production values of recycling and evaluated the performance of recycling performance based upon the estimated production values. Hsu and Liu [5] provided a cost analysis of recycling for waste packaging containers in Taiwan. Bor, Chien, and Hsu [2] presented a market-incentive recycling system for waste packaging containers in Taiwan. Hsu and Kuo [4] provided an amending mechanism for product charge and recycling subsidy in response to the social economic changes for waste packaging containers recycling. Lee and Hsu [ 6, 7] explored the distribution, fee rates, and collection rate of waste containers. This study aims to estimate the amount of waste packaging containers generated by households in Taiwan and also explore its distribution."

Jan 1, 2014

By Tim B. Vanderwood

The mineralogy of dusts from several locations in a lead smelting plant, remotely collected dusts and soils near the lead smelter, and dusts from a secondary copper smelter were examined by reflected light microscopy (RLM) to determine their m1neralogy, texture, and origins. Individual grams were further analyzed by microbeam techniques. Detailed petrographic analysis of the dust has been supplemented by automated scanning electron microscopy combined with energy dispersive x-ray spectroscopy (ASEM-EDS). This technique allows the rapid sizing and chemical analysis of thousands of individual particles in a dust sample, producing particle size distributions as well as statistically meaningful breakdown of a sample into chemical types (e.g., proportion of galena vs chalcopyrite).

Jan 1, 1992

By Akira Yazawa

The similarities and differences in copper, nickel and lead smelting processes are discussed based on the sulfur-oxygen chemical potential diagrams and the free energy minimization assessments using a thermodynamic software. The prominent features of copper smelting are ascribable to the fact that copper has a strong affinity for sulfur but weak for oxygen and the liquid phase immiscibility between Cu and Cu2S. During the oxidation of sulfides, nickel metal is not stable except at temperatures higher than 1500°C, well miscible with its sulfide, and is oxidized more easily than copper. Metallic lead looks as stable as copper during the oxidation of the concentrate but Pb and PbS. are much more miscible with each other and the vaporization loss is considerable. In the reductive smelting of oxides, the effects of oxygen potential and temperature on the copper contents in slag are not significant due to the monovalent character of copper and the reduction of copper content in slag is not easy in practice. The effect of the slag compositions on the oxidic metal contents of slag is much more significant for lead than either copper or nickel. Due to the immiscible nature between Pb and Fe, high grade lead bullion is easily obtained and lead is more tolerant to impurities.

Jan 1, 1998

By L. A. Harris

The formation of coke during coal liquefaction can eventually result in catastrophic failure of the conversion system. Coking typically proceeds by the formation of liquid crystals (mesophase) and the subsequent separation of these crystals from the plastic phase formed during heating of coal. The anisotropy of the mesophase makes it readily detectable in the optical microscope under polarized light. This study examines the solids formed during coal liquefaction processing by optical and electron microscopy. Observations on the relationships between the coke morphology, minerals and inert macerals are presented.

Jan 1, 1982

By Masanori Abe, Yoshitaka Kitamoto, Kazuhiro Nishimura

"Ferrite plating is a chemical processing which utilizes Fe2+ - Fe3+ oxidation to synthesizing polycrystalline films of ferromagnetic spinels (MFe20 4, M = Fe, Co, Ni, Zn, Al, Cr, TI, etc:) directly from an aqueous solution at 24 - 100°C. This low temperature process allows us to fabricate new ferrite film devices on · substrates of such non-heat-resistant materials as plastics, GaAs integrated circuits, and biomaterials. Synthesized from an aqueous solution the ferrite plated ·films are highly biocompatible. Thus various magnetic device and biomedical applications have been proposed and realized using ferrite-plated films. Ferrite-encapsulated polymer microspheres are applied to antibody carries for enzyme immunoassay, and also to toners/carriers for photocopying. Perpendicular magnetic recording media utilizing plated CoNi ferrite films are proposed. The low-temperature synthesized films of NiZn and Co ferrites are potentially used as soft-magnetic and/or insulating layers, respectively at high/microwave frequencies.IntroductionFerrite plating is a processing which facilitates the formation of crystalline spinel ferrite films with various compositions, (Fe, M)30 4 (M = Fe, Co, Ni, Zn, Al, Cr, TI, etc.), directly from an aqueous solution at 60 - 100°C [1]. This opened the door to fabricating novel ferrite-film devices using substrates of such non-heat-resistant materials as plastics and GaAs integrated circuits [2-4]; conventional ferrite film preparation techniques such as sputtering, vacuum evaporation, MBE, LPE, etc., require high temperatures(> -600°C) for crystallization of ferrites, which deteriorates the non-heat-resistant substrates. Recently we extended ferrite plating to be preformed at room temperature [5, 6]. This enables us to use as substrates such organic materials as biomaterials (e.g. enzymes) having very low heat-resistance."

Jan 1, 2000

By Ting Luo, Hongmin Zhu, Kai Huang, Shuanglong Du, Tao Gui, Yifan Xiu

"Poplar cotton, a cellulosic material, was found to adsorb metals ions effectively. In the present study, the biosorption characteristics of Pb(II) onto poplar cotton, were evaluated as a function of pH, contact time, biomass dosage, initial concentration and temperature. Within the pH range investigated (1.0-6.0), the optimal pH value suitable for the uptake of Pb(II) was determined. The maximum adsorption capacity obtained from the Langmuir model is around 0.52mol kg for the poplar cotton sorbent. Equilibration is achieved in 60min for the studied concentrations. Results suggest that the poplar cotton can be directly used as an effective and low-cost biosorbent for removal of Pb(II) from aqueous solution.IntroductionHigh value utilization of various biowastes produced in agricultural, forestry, fishing industries, etc. have attracted great interest from many researchers [1], Biomass, due to its easy availability, great abundance, low cost, easy processing, eco-friendliness and biodegradability, has exhibited exciting potential for being used as raw materials for the preparation of many new hi-tech functional products [2]. For example, using biowastes to synthesize sorbents for application in the removal of toxic substances such as dyes [3], heavy metals from the waste water [4] or in the recovery of valuable metals [5] from the ore tailings and secondary metals resources has made great progress in last decade. In present study, poplar cotton, a kind of white light fluff of poplar trees, like that of dandelion, usually flying in the air each spring was tested as a biosorbent for the remove lead ions from the water. It may also provide some good ideas for new sorbent design. Lead, as one of the typical poisonous heavy metals, for its typical toxicity and extensive pollution, was chosen to test the adsorption behavior of poplar cotton in aqueous solutions."

Jan 1, 2012

By J. E. Klein

Bench scale tests using a stack of ten whole SAES St909 pellets, 6 grams, to crack methane have been completed with pure methane feed. Test conditions ranged from 600 to 800°C at 101 kPa (760 ton) with a methane feed rate of ten sccm. Methane reformation tests, test where hydrogen was passed through a St909 bed after cracking methane, were performed to determine if and how much methane can be generated under "reformation" conditions. Phase structure determinations of St909, composed of a ZrMnFe alloy with aluminum used as a pellet binder, after methane cracking were complicated by the number of materials that can be formed by the elements in the St909 and the carbon from methane cracking. It was determined that the aluminum not only alloys with the Zr, Mn, and Fe in the St909 alloy, but also forms aluminum transition metal carbides in addition to ZrC as the carbon content and the temperature of the St909 increases. Some A14C3 was also found in some pellets. Passing hydrogen over St909 pellets after methane cracking formed methane at various rates in the temperature range of 600 to 800°C. Temperatures of 800°C gave the best methane cracking performance and efficiencies decreased rapidly with temperature.

Jan 1, 2002

By Joon H. Jang

At a selected pH, hydrothermal oxidation of chalcopyrite was carried out under controlled F+,, at elevated pressures and temperatures (172-200°C) by balancing the rate of oxygen injection against the rate of consumption. Chalcopyrite was converted to covellite (CuS) and digenite (CU1.8S) with rejection of iron and sulfur to the solution. Covellite forms in the first stage, followed by nucleation and growth of digenite in the second stage. The effects of rapid and slow injection of stoichiometric quantities of oxygen are compared. Both the covellite and digenite form a porous layer occupying the same volume as the original chalcopyrite grain. An electrochemical kinetic model is presented to correlate the observed results.

Jan 1, 1993