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By T. P. R. de Jong

Dual energy X-ray transmission imaging is extensively applied for safety luggage inspection. Its advantages are its rapid scanning rate (25 to 100 cm/sec) at approximately I mm resolution and simultaneous thickness independent metal identification. This is especially advantageous for secondary scrap metal inspection and automatic sorting. Other applications include metal product inspection, bale control, and waste processing. Recent progress in development of an automatic on-line sorter for bulk solids is presented and discussed. Besides various non-metal applications (solid fuels, wastes etc.) it appeared particularly effective in light metal sorting. As inspection tool better control of difficult to monitor solid bulk streams, batteries, bales and other related metals becomes possible.

Jan 1, 2003

By Sergio N. Monteiro

Jute fabric obtained from discarded sackcloth is a promising low cost and post-used material being considered as reinforcement of polymeric matrix composites. In particular, the combination of this fabric with a recycled plastic constitutes an environmentally correct composite with both economical and environmental advantages. The present work investigates the toughness of recycled polyethylene composites reinforced with up to 40 wt% of post-used jute fabric extracted from discarded sackcloth. Standard Izod notched specimens were impact tested and the results showed an increase in toughness with the amount of jute fabric. Observation of the composite fracture by SEM revealed that the fabric weave, in spite of damages caused by the previous use of the sackcloth, act as an effective obstacle to crack propagation.

Jan 1, 2009

By C. Ramasamy

The tariff reductions on imports, as a part of on-going liberalisation process in India, has fueled competition within and outside India and has, in turn provided an opportunity to reach global markets. This change calls for quality upgrades and cost-competitiveness without impairing the environment. In this context, gas based processes, contributing to improvement in quality and environment as well as processes where controls are applied when gases inimical to environment are involved, are discussed in a remelt/cast-house scenario. The impact of such processes on fabrication cost of sheet ingot is seen alongwith consumption and cost of materials and compared with a world class standard plant in North America.

Jan 1, 1996

By Jilai Xue, Jun Zhu, Liang Liu

"Separation removal of fluorite and calcite from scheelite is a difficult technical operation in current industrial practice with a heating process causing large energy consumption and high production costs. In this work, the floatation separation at room temperature were carried out using two types of skarn scheelite ores. The results showed that CaO and Na203 are better than NaOH as a regulator in pH value. In the rough floatation and first cleaning floatation, CaO (500g/t), Na203 (3000g/t) were used as a pH regulator, waterglass (4000g/t) was as a gangue depressant, oleic acid or sodium oleate were used as a collector. The degree of the obtained W03 concentrate was more than 65% (commercial product).IntroductionThe mainly gangue in scheelite are quartz, calcite, barite and some rare metal ores. There are three main types of scheelite for floatation: scheelite--quartz (silicate minerals) type, scheelite-calcite/ fluorite type, scheelite--calcite/fluorite/barite type. Generally speaking, scheelite--quartz type is separated easily, and others are difficult, on the contrary. The last two kinds of scheelite are always called scheelite--calcite/fluorite (barite) type, because there are similar floatation ability and floatation process between them. Scheelite, calcite and fluorite have same cation - Ca2+, it makes them have close floatation property [1]. Separation removal of fluorite and calcite from scheelite is a difficult technical operation in current industrial practice.The traditional separation method is a heating floatation process (Petrov's process) [2]. It can deal with many kinds of scheelite, and can be obtained stable quality ofW03 concentrate. On the other hand Petrov's process causes large energy consumption, high production costs and bad operational environments. Since 1980s, scheelite ambient temperature floatation has become the mainstream of study [3]. Nowadays more and more studies on scheelite floatation focus on complex reagent system [4, 5], rigid operating rules and at the same time development new regulator [1, 5]. Some research show there are new regulators can concentrate scheelite efficiently, but it may cause high costs, potential pollution and difficulty to spread. Oleic acid and sodium oleate used as collector have high adsorption capacity to scheelite, but same to calcite and fluorite[6]. So, it would not get ideal effect for separation of scheelite. In this work, the floatation separation at room temperature were carried out using two kinds of skarn scheelite ores. Calcium oxide and sodium carbonate was used as a pH value regulator, waterglass was used as a depressant and Oleic acid/sodium oleate was used as a collector. The result of experiment showed that the degree of the obtained W03 concentrate was more than 65% by one time ambient temperature roughing floatation, several times ambient temperature cleaning process."

Jan 1, 2014

By I. A. Ibrahim

Ilmenite, in its natural form, is an inactive mineral from which the selective removal of iron is rather difficult. The reactivity of ilmenite. so that it can be leached with dilute hydrochloric acid, can be enhanced by chemical reduction in solution using a suitable metal as a reducing agent. The present paper aims at the evaluation of an Egyptian ilmenite ore for the production of synthetic rutile by direct leaching with hydrochloric acid in presence of iron powder. In this process, the titanium and iron contents are dissolved; meanwhile, the dissolved titanium is hydrolyzed and re-precipitated leaving mainly iron in solution. Leaching conditions were optimized to obtain less iron in the final solid product. Addition of sufficient amount of iron powder during leaching reduces the dissolved Fe3+ to Fe2+ and reduces the dissolved Ti4+ to Ti3+. The creation of Ti3+ in solution is assumed to have a role in dissolving the ferric iron and hence increasing the reactivity of the ilmenite ore. Synthetic rutile of about 90% TiO2 and 0.77% Fe2O3 was obtained from ore with a grain size 100% passing 200 mesh and a 5-hour leach time with 20% HCl at boiling temperature (110°C) and 0.11 g iron powder / g ore.

Jan 1, 2003

By Dave Tahija

"Many investigations are being performed with the goal of removing carbon dioxide from the atmosphere and permanently storing it in geologically stable settings. At the same time, carbon dioxide in the form of dissolved carbonate is steadily accumulating in the world's oceans. Both carbon dioxide sequestration and oceanic accumulation are constrained by the aqueous thermodynamics of the carbonate system. These constraints are illustrated using the STABCAL computer model to generate potential-pH and aqueous distribution diagrams of seawater in contact with various pressures of carbon dioxide gas. STABCAL diagrams and titration simulations are also used to model some potentially useful cation-carbonate sequestrationsystems.IntroductionAtmospheric carbon dioxide concentrations have risen dramatically in the past couple of centuries and are rising still, primarily as a result of human activities, especially the burning of fossil fuels. Increased atmospheric carbon dioxide concentrations have been implicated as a main cause of global warming but have other effects as well.Rising levels of atmospheric carbon dioxide result in increased concentrations of dissolved carbonate complexes in water, including the oceans. These dissolved carbonates interact with other dissolved substances, altering overall seawater chemistry, most noticeably causing lowered pH levels.Some of these chemical changes are observed directly, for instance the general drop in oceanic pH, [1], while others can be inferred and predicted using thermodynamic modeling. The chemistry of dissolved carbonate in seawater is not especially intricate, as such chemical systems go, but neither is it simple enough to be worked out on the back of an envelope. Interactions between the several simple carbonate species and all the major dissolved cations in seawater should be considered, as well as the effects of competing anions, especially chloride and sulphate, since they are much more abundant than carbonate in seawater."

Jan 1, 2011

By J. Schmidl

In non-ferrous metallurgy the service life of refractory materials typically ranges from several weeks up to three years or more and is strongly dependent on operating conditions. To support our customers with the most viable refractory solution for their needs RHI Magnesita follows a structured approach of thermo-chemical calculations, experimental evaluation from lab scale up to industrial field tests and post-mortem analysis of used refractory materials. This paper will give an overview of the RHI Magnesita refractory selection process and the most recent developments of the experimental setup for the so called HF-IF test. This is a dynamic corrosion test that allows to determine fundamental properties of different refractory material types under process conditions subjected with respective customers process materials. The HF-IF experimental procedure is an excellent tool to simulate refractory wear in industrial processes, diminishing risks associated with plant trials and support decision making to choose the optimal refractory solution for the customer.

By M. A. Cocquerel

The future economic necessity of mining copper ores with a high impurity content and increased environmental awareness will require closer examination of the distribution of arsenic within copper smelting processes. A generalized approach is developed which can be adapted to specific projects for the determination of an overall process configuration to satisfy all requirements in a cost effective manner.

Jan 1, 1983

By Jonkion M. Font

As a comprehensive contribution to the understanding of oxygen-blowing of matte smelting, the copper and nickel solubilities between the FeOx SiO2-MgO slag with saturated SiO2 and the Cu2S-Ni3S2 FeS matte with the NCu/(NcU+NNi) of 1, 0.75, 0.5, 0.25 and 0, in a MgO crucible were investigated at 1573 K under controlled partial pressures of SO2 at 0.1, 0.5 and 1 atm. The partial pressures of SO2, S2 and O2 were controlled by using an Ar-SO2-S2 gas mixture after passing through a sulfur reservoir. It was clarified that, at a given matte grade, the solubility of copper in the slag was independent of pso2 while that of nickel increased with increasing pso2. This notable difference was considered to be ascribable to the chemical formulas of the mono-metallic sulfides in which one copper atom combines with ½ sulfur atom while one nickel atom combines with 2/3 sulfur atom. It was also clarified that, at a given iron content in the matte, the pot and ps2 were independent of the matte species. This was ascribable to aFeS in the matte, which was independent of the matte composition, Ncu/(Ncu+NNi), at a given iron content in the matte.

Jan 1, 1999

By Wing Ka Ng

Substitution of pulverized coal injection by solid biocarbon fuel has the potential to achieve substantial reduction in GHG emissions associated with blast furnace ironmaking. A systematic evaluation was conducted on the performance of solid bio-carbons produced from a single raw biomass source using different pyrolysis technologies. The potential of solid biocarbon in reducing GHG emission of the blast furnace ironmaking process is strongly influenced by its O/C mass ratio. In order to achieve substantial GHG reduction, it is necessary to replace coal injection by solid biocarbon having a low O/C mass ratio. The pyrolysis technology and conditions employed are key parameters influencing O/C mass ratio of the resultant solid biocarbon. Close collaboration between steelmakers and solid biocarbon producers is critical for producing suitable solid biocarbon fuel to replace pulverized coal injection. A successful partnership should pave the way in achieving substantial reduction in GHG emissions of the blast furnace ironmaking process.

By Zachery Zanetell

Flotation circuit performance has become increasingly more challenging due to the complexity of available ore sources. To optimize value mineral recovery, the mineralogical composition of the ore should be evaluated and understood. Utilizing a variety of mineralogical and analytical tools, flotation processing challenges can be overcome and potential limitations understood. In this paper, several case studies will be discussed in terms of the value that has been provided through the use of mineralogical analysis to optimize flotation performance.

By Dany Racine, Daniel Marceau, Denis Laroche, Dmitry Lukovnikov

Carbon base materials play a critical role in the performance of Hall-Héroult cell. The determination of their thermo-physical properties is of primary importance for modeling and designing complete cell systems. However, overcoming the associated experimental hurdles is complex and often underestimated. Of them are the Poisson’s ratio measurements and the continuous oxidation/burning of the materials at temperatures above 200°C. The novel procedure developed in this research is based on the Gleeble® 3800 system. Its vacuum chamber allows test with a chosen atmosphere at temperature of more than 1000°C. Young’s modulus, Poisson’s ratio and the coefficient of thermal expansion values can all be adequately measured using a single test. Cylindrical carbon samples (: 50mm, L: 100mm) were tested in the modified system at temperatures ranging from room to 950°C without any trace of oxidation. The resulting values were also in good agreement with literature data for a specific graphite material.

Jan 1, 2015

By Tianzu Yang, Weifeng Liu, Lin Chen, Wei Chen, DUCHAO ZHANG, HUI XIAO

Oxygen-rich side blow bath smelting (OSBS) technology was developed in 2000 based on Vanyukov process. This technology exceeds the traditional pyrometallurgical methods by its great processing capability, high metal recovery and environmental-friendly property. In the past 15 years, OSBS technology extended its application area from lead industry to bismuth, antimony and waste recycling industries, etc. This paper introduces the history and new developments of OSBS technology. The typical industrial applications examples of the OSBS technology in China, including high lead slag reduction, low grade bismuth-lead concentrate smelting and metallurgical waste recycling, are reviewed. Especially, the unique furnace properties and technical parameters are compared. Finally, the potential research directions of OSBS technology are summarized.

Jan 1, 2016

By K. B. Shedd

Questions regarding possible adverse health effects from exposure to zeolites arose when the inhabitants of two villages in Turkey were found to have high incidences of mesothelioma, a disease generally identified with exposure to asbestos. No asbestos deposits are known in the area, but some fibrous zeolites have been found. Further investigations have resulted in conflicting opinions as to whether fibrous zeolites are related to the high incidence of mesothelioma in Turkey. The U.S. Department of the Interior, Bureau of Mines examined the habits of domestic zeolites by scanning and transmission electron microscopy. Only erionite and mordenite particles possessed acicular to fibrous habits. With the exception of a rarely occurring woolly erionite sample, the fibrous zeolites were not dimensionally equivalent to asbestos.

Jan 1, 1982

By Joo Hyun Park, Kyu Yeol Ko

The viscosity of the CaO-SiO2-xMnO-yCaF2 slags (C/S=1.0; x=10, 40%; y=0 to 15%) was measured to clarify the effect of CaF2 on the viscous flow of molten slags at high temperatures. Furthermore, the Raman spectra of the quenched glass samples were quantitatively analyzed to investigate the structural role of CaF2 in a depolymerization of silicate networks. The critical temperature of the slags abruptly increased at 15%CaF2, which was confirmed to originate from a crystallization of cuspidine using XRD analysis. The viscosity of the slags continuously decreased by CaF2 addition in the 10%MnO system, whereas the viscosity of the 40%MnO system was not significantly affected by CaF2 addition. The effect of CaF2 on the viscosity of the slags was quantitatively analyzed using micro-Raman spectra of quenched glass samples accompanying with a concept of silicate polymerization index, Q3/Q2 ratio. A polymerization index continuously decreased with increasing content of CaF2 in the 10%MnO system, whereas it was not affected by CaF2 in the 40%MnO system. Consequently, the bulk thermophysical property of the CaO-SiO2-MnO-CaF2 slags was quantitatively correlated to the structural information.

Jan 1, 2014

By Zhihe Dou

SHS reaction system has advantages of heat flux density, energy concentration and reaction speed, with sufficient conditions in thermodynamic and kinetic reaction. This paper invented a new technology of SHS metallurgy of preparing melting point alloys and refractory compounds using its own chemical energy. SHS-leaching process for preparing nano boron powder or ultrafine boride powder and SHS-casting process for preparing titanium-based alloy and immiscible alloy were studied. The results indicate that highly active boron powder of greater than purity of 93%, particle size less than 100nm and purity greater than 98.5%, particle size less than 400nm REB6 can be prepared. With SHS-Casting process, the oxygen content of less than 0.59% ferrotitanium, oxygen content of less than 0.5% titanium alloy and ?40-80*100mm large size of CuCr, Cu-Fe alloy ingots were prepared. This technology has greatly enhanced the thermal reduction method added values of preparing metallurgical products and its competitiveness.

Jan 1, 2014

By Huyang Xie, Rishi Raj, Vera A. Versteeg

"A new method for MOCVD has been developed in which a precursor solution is directly injected into a reaction chamber. The vaporization of short pulses of liquid is facilitated by atomization with a piezoelectrically-operated nozzle. The system has been used successfully to grow oriented, thin Ti02 (rutile) films on sapphire substrates with the crystalline relationship (101)[010]R I (1120)[0001]s. A growth rate of approximately 2 monolayers per pulse was achieved at 650°C for a reactant impingement rate of about 800 monolayers per pulse. Also, epitaxial LiTaO3 thin films were grown on (0001) sapphire from a single source, bimetallic precursor, lithium tantalum hexa-t-butoxide as the precursor. X-ray diffraction shows that the LiTaOa c-axis is normal to the sapphire surface. The x-ray pole figure and crosssection TEM diffraction show that the films were also in-plane oriented, with sapphire [1010] parallel to lithium tantalate [1010]. These films are shown to have extremely low optical attenuation, and refractive index that compares well with bulk values.IntroductionMetalorganic chemical vapor deposition (MOCVD) techniques have come into increasing use in recent years, due to the growing versatility and availability of precursors and improved environmental advantages over the halogenated compounds used for conventional CVD. Most commonly, the films are deposited by dissolving the metalorganic reactant (typically a metal alkoxide) in a carrier gas, which is carried through heated lines to a heated substratel . The metal alkoxides decompose by pyrolysis, leaving the films on substrates. While this method has been used to produce excellent epitaxial and heterepitaxial films, it has the disadvantages of complexity: the precursor must be heated to fix its vapor pressure, the gas flow rate carefully controlled, and the carrier lines heated to prevent condensation before reaching the reactor. Additionally, this conventional method cannot be used with certain low-volatility precursors that decompose upon heating."

Jan 1, 1994

By Jilai Xue, Jun Zhu, Germain Kouma Ndong, Qiaochu Liu, Luxing Feng

"High-temperature oxidation and corrosion behaviors of Ni-Fe-Cr alloy as inert anodes for aluminum electrolysis have been studied in oxygen and molten electrolyte. The oxidation and corrosion scales on the anodes tested were analyzed using XRD and SEM-EDS. The oxidation rate is found to increase with increasing temperature from 700 °C to 950 °C, which can be approximately described by an inverse power rate function. The oxidation scales at 750 °C, 920 °C and 950 °C contain Cr-rich phase along with FeCr204 and (Feo.6Cro4)203. The corrosion extent of Ni-Fe-Cr anodes in electrolyte is dominated by temperature, which can make the scales thickness double from 700 °C to 750 °C or from 920 °C to 950 °C. Cr and Fe in the scales on the anode in electrolysis corrode preferentially into the molten electrolyte, while the nickel oxides could better sustain the corrosive environment in electrolysis. The results can be useful for developing inert anode material for potential application in aluminum electrolysis.IntroductionThe development of an inert anode for aluminum electrolysis has been a long term goal for aluminum industry. The present process for primary aluminum production involves the reduction of alumina with carbon anodes, forming carbon dioxide:"

Jan 1, 2013

During electrowinning of nickel chloride, hydrochloric acid was regenerated instead of chlorine in a two membrane cell, by segregating the chloride catholyte with an anion exchange membrane, and the sulphate anolyte with a cation exchange membrane from the middle electrolyte (ampholyte) compartment. Successful operation of such a cell depends on controlling chloride leakage through the cation exchange membrane to the anolyte. Small amounts of chlorine gas could be detected in the oxygen evolved at the anode. In this paper, the chloride. leakage as a function of various types of cation exchange membrane and different composition of the anolyte is reported and discussed. Ag+ was added to the anolyte to eliminate chloride leakage to the anode. The cell voltage, electrode potential and voltage drop over the membrane as a function of current density has also been investigated.

Jan 1, 1996

By Florian Kongoli

"Lime ferrite" slag with limited silica content has proven to be a valuable choice in the modem processes of copper smelting and converting due to several advantages that this slag offers compared to classical silicate slags. Nevertheless the liquidus surface of this slag has been experimentally measured only at low oxygen potentials such as in equilibrium with iron or near it and in air. Although most of the smelting and converting processes that use this slag occur at intermediate oxygen potentials, the liquidus surface of this slag is not known at these conditions and the effect of oxygen potential and silica has not been correctly understood. This has brought some confusion in literature as well as in the industrial practice. In this work the liquidus surface of the calcium ferrite slags has been quantified by the means of a new thermophysicochemical model and a new type of liquidus surface diagrams which are very convenient for any industrial process that uses calcium ferrite slags. These diagrams can be easily used to select the lowest liquidus temperature of calcium ferrite slags at a minimum cost and can help design several fluxing strategies in copper smelting and converting processes. The effect of the oxygen potential and silica is also quantified and important industrially related conclusions are drawn.

Jan 1, 2003