Search Documents

By Roy J. M. van Lier

In industrial aqueous solutions, germanium generally occurs in trace amounts amid high concentrations of other metals, such as zinc, copper and iron. Separation of germanium from these metals as well as its isolation from gallium and indium pose a real challenge to the hydrometallurgist. After a brief discussion of the aqueous chemistry of germanium, this paper reviews the flowsheet of the Apex Mine in Utah. The Apex property was the only mine in the world to be operated primarily for production of gallium and germanium, but apparently closed due to great operating difficulties. Several process variants proposed for the treatment of the Apex ore, including bioleaching methods, are addressed. Following a more general description of the behavior of germanium in hydrometallurgical zinc processing streams, available technology for its recovery from aqueous solutions is summarized. Precipitation, solvent extraction, ion exchange, electrowinning, ion flotation and liquid-membrane separation are all outlined in terms of the aqueous chemistry of germanium. Finally, the production of high purity germanium dioxide and metal is briefly discussed

Jan 1, 1995

By Nils Eivind Kamfjord, Halvard Tveit, Ingeborg Solheim

"Because of its negative environmental effect the attention towards NO emissions increases. This again leads to new demands from the authorities for better surveillance and control of emissions. Earlier and recent industrial measurements towards FeSi- and Si-metal furnaces reveal quite high NO-emission. The NO is believed to be produced in the combustion zone above the furnace surface, mainly as thermal NO.In order to expand the knowledge on NO-formation in silicon metal production, a pilot scale experiment in a 440 kVA silicon furnace has been carried out. The experimental set-up was designed with a view to be able to copy and manipulate the formation mechanisms for NO by controlling the flow of false air into the off-gas system.The resulting NO-values corresponding to the different air inlet to the furnace top, show significantly differences between the different air inlet geometries.IntroductionNOx is the common notion for the two gases nitric oxide (NO) and nitrogen dioxide (NO2). Since combustion of fuels, such as gasoline, diesel, bio diesel, propane, coal, and ethanol, forms NOx the dominating contributors to NOx emissions are the on-/offshore transportation industry and power generation based on fossil fuels [1]."

Jan 1, 2012

By Mukesh Jain

The liquor from potroom wet scrubbers is treated with lime to precipitate the soluble fluorides. The solids after filtration, referred to as scrubber mud, contain in addition to calcium fluoride, alumina, carbon, tars including polyaromatic hydrocarbons (PAH), cryolite and pachnolite and are considered hazardous. This communication deals with the pilot plant scale calcination of scrubber mud with a rotary kiln to obtain non-hazardous fluoride raw materials. Air classification was performed to separate the mudinto aluminarich andcalcium fluoride rich fractions which were then calcined. With proper control of calcination parameters and addition of lime, the carbon and tars were destroyed and hydrogen fluoride emissions were controlled. The calcined products could be used in the steel indusny as a fluxing agent or as a substitute for fluorspar in the production of aluminum fluoride.

Jan 1, 1994

By A. Christlo

Short circuit detection in 1984 involved nine inspectors for production rates of 43,000 tpa. Trials indicated the feasibility of applying cell voltage monitoring to short circuit detection and improving operational efficiency. A computerised cell voltage monitoring system was commissioned in February 1986, to read voltages from 648 cells. The system incorporates 16 evenly distributed work face units which communicate with a central computer system. Provision has been made in the computer program for the automatic adjustment of cell reference voltages. This allows for the effect of polarization and other process variables which might other wise interfere with short circuit detection. The work face units can continue to work independently for several days should this become necssary. Current efficiencies have been maintained and the number of inspectors reduced from nine to five.

Jan 1, 1987

By S. J. Hogan, T. William

"By the year 2000, the steel industry, not only in the United States but in the rest of the world, will undergo significant changes. On the other hand, there will be a number of areas in which change will be minimal.The current capacity of the industry worldwide is approximately 800-810 million metric tons. This may grow to some extent, as Third World countries install capacity. However, much of it will be neutralized as the industrialized countries shrink their current capacities.There will be several breakthroughs in terms of technology, some of which deal with the production of iron outside of the blast furnace. However, these processes will not be far enough advanced by that time to replace the blast furnace, rather they will supplement it.In terms of steelmaking and the subsequent rolling process, there should be a number of basic improvements. The strip mills will roll sheets with a very slight variance in gauge, which will give the customers a better product for automatic stamping machines. Ordinary carbon steel, in a number of instances, will be replaced by high-strength, low-alloy steel, which will reduce the tonnage necessary for present-day applications, such as construction.The corporate organization will be significantly changed as joint ventures and mergers will reduce the number of companies, as well as facilities in operation. This will enable the industry to reduce its capital investment and improve operating costs, so that it will be able more effectively to compete with other materials, such as plastics, cement, aluminum, etc."

Jan 1, 1988

By K. Osseo-Asare

The molecular structural and solution chemical characteristics that underlie the surface activity of solvent extraction reagents are highlighted, with particular emphasis on the tendency towards reverse micelle and microemulsion formation. The physicochemical factors that lead to microemulsion-enhanced solvent extraction with chelating extractants are elucidated Membrane-based contactor systems are described which are uniquely suited for enhanced solvent extraction with microemulsions. The possibility of combining solvent extraction with microemulsion-mediated materials synthesis is discussed.

Jan 1, 1996

By N. J. Themelis

In the last two decades, the Outokumpu flash smelting process has become the dominant new technology for copper smelting and has? also been applied to the smelting of other metal sulfides. The application of oxygen enrichment and improvements in concentrate burner and furnace design have resulted in ever increasing smelting rates per unit volume of the reaction shaft. This paper examines the. rate phenomena taking place in the reaction shaft of the Outokumpu furnace and compares information obtained from a mathematical model of heat and mass transfer rates to results obtained in pi1ot tests conducted at Pori, Finland, and to actual performance of a number of flash smelters around the world. 2?

Jan 1, 1985

By Cang Daqiang, Bai Hao, Li Ning, Liu Xueting, Lu Xin, Zhao Lihua, Li Hongxu, Wei Wei

"Based on the principle of carbon balance, a model was built to calculate C02 emissions of each process and correspondingly the total course of production in iron and steel making. The data from a typical integrated steelworks in China was applied in the model. The results show that the BF and coking process account for the most emissions. Generally, C02 emissions in integrated steelworks depend on three factors, resources utilization efficiency, energy utilization efficiency and energy consumption structure, which were considered in an equation in this paper. Especially, General Emission Factor (GEF) was proposed to assess the relationship between C02 emissions and energy consumption. The results show that, higher GEF will result in more C02 emissions with the same energy consumption and in iron and steel making, the optimization of energy structure and development of eco-industrial park both have significant benefit on the carbon reduction.IntroductionThe Global Warming resulting from the increase of Greenhouse Gases (GHGs), especially C02, in the atmosphere has become the main reason of global climate change, and the carbon reduction is one of the most important ways for the sustainable development [1]. The iron and steel making is a manufacturing industry based on iron-coal high temperature chemical process, in which plenty of C02 is emitted. According to the data from IPCC (Intergovernmental Panel on Climate Change) in 2001, iron and steel making emitted about 650 million tons ofC02 every year, which is the fourth largest industry of the fossil energy consumption [2]. According to the data from EEA (European Enviromnent Agency) in 2006, iron and steel making is the largest source ofC02 emissions, which accounted for about 18% of the total C02 emissions in European manufacturing industry [3].It is estimated that the application of various well developed energy-saving technology, such as Coke Dry Quenching (CDQ), Top Pressure Recovery Turbine (TRT) and Coal Moisture Control (CMC), can make the C02 emissions reduced by 0.5%-3% in iron and steel making, and the further C02 emissions reduction can be achieved if more new energy saving technology is applied, such as sintering plant heat recovery, electricity generation with steam generated from converter and the various by-products gas and the hydrogen making process from COG[4,5]. In addition, the application of membrane separation technology is well expected in iron and steel making [6]. For example, the application of C02 Capture and Storage (CCS) in blast furnace combined with the Pure Oxygen Top Gas Recycled BF (TGRBF) technology can reduce the C02 ennss10ns greatly by about 50%-60% [4].That is, as a kind of C02 end-treatment technology, CCS applied with other technology of C02 recovery would be more meaningful. Actually, reduction of the C02 emissions by changing the structure of energy consumption and raw materials with new process of iron and steel making, such as direct reduction process or smelting reduction process [4,7,8], is the trend of ferrous metallurgical engineering, which is regarded as a kind of source-treatment technology. In this sense, source-treatment technology is more pivotal for the solution of carbon reduction in the future than the current popular energy saving technology. Hence, it is necessary to build the C02 emissions model based on the iron and steel making process and evaluate the relationship between the energy saving and C02 emission reduction."

Jan 1, 2012

By Guy L. Fredrickson

A modified transpiration reactor was used to measure the composition of the equilibrium gas phase formed above compounds in the Hg-O-S system at high temperatures (600 to 900K). A thermodynamic database {(AGo°f AH°t. AS°t)} for-HgO, HgS, HgSO4, Hg2SO4, HgSO4?HgO, and HgSO4?2HgO was developed based on the experimental results. Prior to this study, only estimated data were available in the literature for the sulfates and oxysulfates at temperatures above 298K. A series of vapor pressure' stability diagrams were constructed from 473 to 973K with isobars of Hg(g), HgO(g), S2(g), and SO3(g). These diagrams were found to be significantly different than those available previously and do provide insight to the phase relations of importance during the thermal processing of Hg-containing wastes. The thermodynamic results were used to conduct a series of Gibbs energy minimization calculations for a thermal processor' afterburner system for the treatment of HgS-containing wastes. The retention of Hg in the discharge calcine was examined as a function of temperature and excess air. Hg was found to report to the calcine as HgSO4, Hg2SO4, or HgSO4 HgO depending on the process conditions, and Hg retention occurs at temperatures as high as 930K. The precipitation of Hg-containing phases from cooled afterburner discharge gas starts at approximately 900K and the cooling of the gas an additional 30K (to 870K) results in over 50% of the Hg being preCipitated as HgS04?HgO. It was also determined that for small amounts of Hg present in sulfide concentrates during roasting, the Hg will be retained as HgSO4 or HgSO4?HgO at temperatures as high as 870K.

Jan 1, 1996

By J. M. Demarthe

MINEMET RECHERCHE (IMETAL Group, formerly Le Nickel-Penarroya-Mokta) has studied on a laboratory scale and patented a new process to recover metal values -copper- from sulphide ores and concentrates. It combines a cupric leaching, solvent extraction and copper sulphate electrowinning according to the main following steps - A direct and selective leaching of copper sulphide ores or concentrates at atmospheric pressure with cupric chloride to form cuprous and ferrous chlorides and elemental sulphur. Pyrite remains in the sulphur residue. - The leach solution is separated into two parts -In the first one, air is injected to precipitate iron as goethite. The oxidation step can be easily realized at atmospheric pressure by maintaining an excess of cuprous and-ferrous chlorides in the liquor. Copper is extracted from the second part as cupric ion by an LIX reagent. Direct injection or air in the mixing chamber maintains good extraction conditions, so that only one mixer settler is required. - Iron, in the form of ferrous ion, is not coextracted. - Copper is stripped from the organic phase, transferred into a sulfuric phase and sent to sulphate electrowinning cells, which are now conventional in copper metallurgy. - Only electricity and air are required. After a feasibility study, the next step will be to develop it on a pilot and commercial scale.

Jan 1, 1976

By James R. Craig

The slags generated during gasification of petroleum coke are heterogeneous and con-sist of many different phases. These phases are important because their physical properties affect the operability of gasifiers and because they concentrate many elements that are present in the petroleum coke feed in only minor to trace quantities. An understanding of the chemistry and physical nature of these slag phases is necessary to predict behavior in the gasifier and in considering the ultimate use or disposal of the materials. Slags typically consist of silicate glasses, calcium-silicates, free iron-nickel metallic phases, iron sulfides, and aluminum oxide spinels enriched in iron, chromium, and vanadium. The partitioning of elements among these phases has been analyzed and will be discussed.

Jan 1, 1989

By Carlos Mauricio Fontes Vieira, Sergio Neves Monteiro, Thiago Samarão Motta

This work has as its objective to characterize ceramic bodies formulated with ornamental rock waste and two different clays to produce ceramic paver. Specimens were made by uniaxial press-molding at 20 MPa and then fired at 950 and 1050oC respectively. The determined technological properties were: plasticity, dry bulk density, linear shrinkage, water absorption and flexural rupture strength. The results showed that the type of the clay has strong influence on the properties of interest for heavy clay ceramics. The investigated waste must be incorporated in small amounts to avoid increasing in the porosity of the ceramics.

Jan 1, 2015

By T. Kimura, H. Ohba

"Much effort has been made to reduce the energy requirement in zinc electrowinning. In order to keep energy consumption low, either to make cell voltage low or current .efficiency high is necessary. Decrease of cell voltage practically depends on how to reduce ohmic resistance in the electrolyte and the anode crust. To realize these, new concept was proposed and the pilot plant has been operated. The space between a cathode and an anode is halved by utilizing the frame insulator. With these frames the anodes and cathodes compose of a unit of electrodes, and this unit is handled by newly designed electrode handling machine (E.H.M.). The process includes lifting up electrodes, expanding the space between a cathode and an anode, cleaning them, stripping the deposited zinc and returning the unit to the cell. As a result, cell voltage is kept as low as calculated and predictable energy reduction has been achieved. IntroductionIn the recent trend of a rapid appreciation of the Japanese yen, Akita Zinc Refinery of Mitsubishi Metal Corporation has been confronted by problems of relatively high operating costs. In order to compete with other overseas zinc refineries, it is necessary to reduce the cost of zinc production, especially the cost of electric power which now accounts for .up to 35 % of the entire cost of production. Three fourth of the electric power used at Akita Zinc Refinery is for the electrolysis. Therefore it is extremely important to reduce the cost of electrolysis.There are two possible measures for solving the problem; one is to use more nighttime electricity taking the advantage of its inexpensive power price, and the other is to reduce electric power consumption.As a part of a rationalization plan carried out in 1986, Akita Zinc Refinery increased the number of operating cells. As a result, when nighttime electricity is used, the silicone rectifier has been able to operate at full capacity. Moreover, by new schemes of ""increase of area for electrodeposition by ralslng the liquid level of electrolyte"" and ""increase of the number of electrodes in each cell"", current density could be lowered and as a result, the electric power consumption has been improved. In order to raise nighttime ratio even higher, installation of an additional rectifier and cells would be required."

Jan 1, 1988

By Brian P. Atkin

The NISOMI-81 opaque mineral searcil and identification system uses quantitative color values (Pe, dA, y) and VHN as its determinative para-meters. The system is designed to operate on a Radio-Shack TRS-80 micro-computer which is interfaced to a motorised diffraction grating mono-chromator (WILSCAN). Using an interfaced monochromator/photometer combination a typical identification including the measurement of the photometer data on both specimen and standard, calculation of color values and a computer search takes about 6 minutes. The data file contains 240 minerals at present but can easily be expanded as reliable new data become available.

Jan 1, 1982

By Yu Hu, Gabriella Tranell, Song Zhang, Eivind Johannes Øvrelid

"In the present research, recycling feedstock of silicon for Photovoltic (PV) application is investigated. Whether these recycling feedstocks are reliable in the future use is discussed in this work to assess the properties of the crystal silicon ingot, which is commercially pulled from top-cuts of casted multicrystalline ingot via one kind of Czochralski method - FerroTech. Dopant is the acceptor type Boron (B) and growth direction was <100>. Crystal diameter and the length were 190mm and about 1700mm, which were controlled by the temperature and the pulling speed, then cut to 156mm * 156mm wafers with 2000um and 200um thickness. Resistivity measurements of these wafers by Four Point Probe (FPP) are in good agreement to the calibrated profile after Rapid Thermal Process (RTP). In this work, the Minority Carrier Lifetime MCI, shown by Carrier Density Image (CDI) and Quasi Steady State Photo Conductance (QSSPC), gives the mapping results on the cross section and the relationship to the injection level, increases in an arrange from 40us to 90us along the ingot height, which is abnormal distribution compared to the standard ingot. Then Oxygen and other metal impurities distributions, measured by Flourier Transform Infra - Red (FTIR) respectively, account for the novel phenomenon of the continuously increased MCI. Various types of heat treatments were performed on these wafers (different ingot and different positions) in N 2 and 0 2 mixture atmosphere. Before and after heat treatment, micro-defects were revealed by copper decoration and etching work. Solar cells are fabricated by Energy Research Center of the Netherlands from the experimental ingot, and processed under an industrial standard line. Compared to results of the reference mono-crystalline and multi-crystalline silicon solar cells, the performances of experimental ones show excellent efficiency values up to 18.5%, and Jsc values up to 37mA/cm2.IntroductionThe PV industry has gone through rapid development, with a high growth rate resulting in an increasing demand for silicon feedstock. In addition, costs in production need to be reduced such that solar energy can compete other conventional and renewable energy. Searching low cost, reliable and efficient feedstock is one promoting way to improve and enhance the competitiveness of the PVindustry.More and more researchers start searching new raw materials for PV application [1]-[4]. The key to make full use of low cost raw materials is to control the distribution and effect of impurities, such as Carbon, Nitrogen, and other metal contamination [5]."

Jan 1, 2013

By Jorge Alberto Soares Tenório

Household zinc based batteries contain some heavy metals such as zinc, manganese and mercury. There is a large effort from manufacturers in order to eliminate the last one. As a municipal waste, the disposal of batteries has become an increasing worry. The aim of the present work was to characterize dry batteries scraps, and establish a flowsheet for their processing. This was done using unit operations of mineral processing and parameters and yields of each stage have been defined. Such procedures have been chosen due to their low cost. The operations were hammer mill grinding, size separation, magnetic separation and specific weight separation in water. The characterization step was done through chemical analysis and x-ray difiactometry. After size classification, it was verified that 76.6% of the total amount of zinc was over 1.70mm. This fiaction was constituted basically of zinc and some coarse pieces from the steel body, paper and plastics. This fraction was submitted to magnetic separation followed by specific weight separation in water. A visual examination showed that during the grinding process, graphite was concentrated in the finer fractions. Manganese concentration in the fractions over 6,35mm was less than 2%. This means that there was low contamination by the paste in this fraction. It was due to the entrapment of the paste by steel scraps (from the body) and zinc (from the cup) during grinding.

Jan 1, 1999

By E. T. White, Dean Ilievski

"Mathematical modelling of the precipitation process requires that the kinetics of crystal growth, nucleation and agglomeration be known. This paper reviews the current state of knowledge on these precipitation sub-processes (ie. growth, nucleation and agglomeration) and describes a number of experimental techniques for estimating their kinetics. The experimental methods used to generate the precipitation data and the data analysis techniques used to extract the kinetics information from the data are discussed separately. There is no universal ""best"" technique for determining the kinetics. However, studies on multi-crystal systems are more reliable for modelling purposes than are single crystal studies. The selection of a technique will depend on which sub-processes are present. A problem with all kinetics studies is that there is generally a large uncertainty in the estimated kinetic parameters. This stems from the scatter in the experimental data being further propagated by the mathematical techniques used to extract the kinetic parameters.IntroductionCrystallisation operations, including precipitation, are widely used in a number of hydrometallurgical processes to recover a desired component or to remove an undesired impurity. The goals of industrial precipitation processes are to maximise the recovery while maintaining product quality (generally product crystal size distribution, purity and morphology and product handling properties). Knowledge of the precipitation mechanisms and kinetics is invaluable for designing new precipitators or for improving existing units. The mechanistic and kinetic information is generally incorporated into mathematical precipitator models, which are then used for process design and optimisation."

Jan 1, 1996

By Kota Nakashima

Residues from titanium smelting tend to contain scandium. The scandiumis discarded because no suitable process exists for its recovery from the residue. Valuable-metal recovery from discharged residue is critical for environmental conservation and to achieve a sustainable society. Since 2015, JXNippon Mining&Metals has been developing a process for scandium recovery from the residue of a titaniumsmelting process. The process consists of the following steps: scandium concentrating by classification or neutralization, selective scandium leaching, impurity removal by neutralization, solvent extraction of scandium by using D2EHPA, purification, and roasting. We optimized the above steps to achieve an effective process to obtain scandium oxide (Sc2O3). In this paper, we introduce results from the bench-scale test of the scandium recovery flowsheet developed by JX Nippon Mining & Metals.

By James M. Fragomeni

"The mechanical behavior of an Al-Li alloy was studied and related to the extrusion processing parameters, the plastic metal flow during defonnation, the anisotropy, and the microstructure. The extrusion temperatures, strain rates, extrusion ratios, billet temperatures, and extrusion geometries were varied during processing and correlated with the microstructure and properties. The extrusion processing variables were related to the mechariicar behavior, anisotropy, and microstructure through the ZenerHollomon parameter i.e., the temperature compensated strain rate. Based on optical and electron microscopy studies it was found that regardless of the extrusion conditions, the various microstructures for the most part were unrecrystallized for both the as-extruded and the solution heat-treated conditions. Smaller grain sizes were correlated to larger Zener-Hollomon parameters. The extrusion temperature and ratio did not significantly affect the strength or ductility as did the section geometry, which had a large affect on these mechanical properties. The anisotropy of the properties varied substantially when comparing the extruded longitudinal versus transverse grain orientations.IntroductionThe extrusion process also has a substantial influence on: the microsfructure and mechanical properties of a material that is Athens, Ohio, 45701 fonned The plastic defonnation that occurs during the extrusion process alters the grain size, crystallographic texture, anisotropy, subgrain size, dislocation density and various other microstructural features. Often the material being extruded is not homogeneous, therefore variations in the microstructure and properties occur across the cross-section of the final extruded product. The mechanical properties and microstructure can also vary with length since it is hard to maintain a constant temperature throughout the extrusion process. The extrusion temperature often varies from the heat generated during the extrusion process. The demonstration material that was extruded for this .study was an aluminum alloy containing 2.6wt, % lithium and 0.09wt.% zirconium. This alloy was strengthened by heat treatment causing nucleation, growth, and coarsening of coherent metastable o' (Al3Li) precipitates in the microstructure. The ? precipitates which are a consequence 9f artificially aging the AlLi alloy, are spherical, ordered, and coherent with the aluminum matrix and impede the dislocation glide inotion during plastic defonnation. Theo particles grow homogeneously in the matrix, and have the Cu3Au (L 12)"" superlattice crystal structure. Aluminum-lithium alloys are used primarily for aerospace structural applications since they have attractive properties such as a lower density and higher elastic modulus than conventional 2XXX and 7XXX alloys."

Jan 1, 2000

By Filippos Patsiogiannis

Laboratory size (4.5 kg) low carbon steel melts were deoxidized using Al and FeAl (33% Al), with and without synthetic fluxes, in alumina and zirconia crucibles. The dissolved oxygen, total oxygen, soluble aluminum, insoluble aluminum, silicon and carbon contents in the melt were determined as a function of refining time and temperature. It was observed that the reaction between aluminum and oxygen in solution closely follows thermodynamic equilibrium. Silica present in the alumina crucibles was found to be a source of oxygen for the melt, while this was not the case for zirconia crucibles. Reoxidation of the melt occurred through oxygen pick-up from the atmosphere. The extent of this reoxidation was found to be a function of oxygen content of the bath and the slag cover on the surface of the melt. The effectiveness of calcium-aluminate based fluxes in protecting the melt from the reoxidation and in increasing the rate of removal of inclusions was evaluated.

Jan 1, 1992