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By Y. F. Liang

Fe-6.5wt.%Si alloy has excellent soft magnetic properties compared with conventional silicon steel. It is very brittle at room temperature due to appearance of ordered phases, like B2 and DO3. In this paper, we investigate the effect of ordering on cold workability of this alloy. Methods of rapid quenching and hot rolling were utilized. It is found that rapid quenching and proper heat treatment of the hot rolled sheet could decrease the degree of order due to the very high solidification rate and high cooling rate. The rapid quenched sheet and hot rolled sheet after proper heat treatment could be cold rolled without crack. Microstructure, phase ordering, micro hardness, and cold rolling properties were investigated by Optical Microscope, X-ray Diffraction, Micro Hardness Indenter and Four-high Mill.

Jan 1, 2009

By T. V. Jayaraman

Fe-Ga alloys, with compositions around 27.5 at % Ga, can be heat treated to obtain ? (ordered bcc), DO19 (ordered hexagonal), and L12 (ordered fcc) ordered structures. Our earlier work using polycrystalline samples had shown that magnetostriction is strongly influenced by ordering in this alloy. Here more detailed study of the correlation between ordering and magnetostriction using single crystals of Fe 27.5 at. % Ga alloys is reported. Single crystals of Fe 27.5 at % Ga were grown using Bridgman single crystal growth technique. X-ray and electron diffraction were used to study the ordering in this alloy. Magnetostriction measurements were carried out at no load conditions. Elastic constants were measured using Resonant Ultrasound Spectroscopy.

Jan 1, 2006

By Tony Lipiec, Ian Orford

"A key part of plant design is the selection of the design tonnage which is the hourly tonnage target that the equipment selection is based on. Its selection is critical for ensuring that the nominal tonnage which is critical to the financial performance of the project will be met. With deposits being developed at lower grades, higher tonnages and a higher degree of hardness variability, it is essential to ensure that the design process selects the comminution equipment which will be able to deal with the impact of this ore quality variation.Ore hardness and its variance are key factors to be taken into consideration for the selection of the design tonnage. It is well accepted that for the nominal or name plate tonnage to be consistently achieved, it is necessary to base the design tonnage on a hardness value greater than the average ore hardness of the deposit to be mined. The question is how much greater should this design value be to ensure that the nominal tonnage is met to the satisfaction of the project financial model. Standard industry practice is to set the design tonnage by:1. Select an ore hardness percentile that is greater than the average ore hardness to be the basis of the nominal tonnage. Typically either the 75th or 80th percentile value from the data set will be selected.2. Selection of a design factor to multiply by for determining the design tonnage, i.e. the design tonnage = tonnage (based on the average ore hardness) multiplied by design factor.This paper discusses the selection of the design ore hardness through the use of modelling or the use of a design factor. It further shows the impact of ore hardness variance on the capacity of the process and its ability to meet the nominal tonnage. Insight is provided as to what ore hardness percentile value should be selected balancing the shortfalls of tonnage for ores harder than the design value versus the above target production achieved for ores softer than the design ore hardness."

Jan 1, 2016

By J. Egan

The recovery of gold by ore leaching is influenced by the size of the particles and the chemical environment. Within the experimental error associated to the testing of gold ore, results of a series of leaching tests conducted with natural ores rather than monosized samples confirm that gold dissolution increases with decreasing ore particle size. The tests also indicate that the dissolution of gold in the ore within a size interval is weakly affected by the intensity of the size reduction method.

Feb 27, 2013

By N. H. J. Freire, D. Majuste

In this paper, the effects of some organic compounds on the current efficiency, cell voltage and specific energy consumption during nickel electrowinning, and on the deposit features (morphology, crystallographic orientation and nanohardness) were described. The organics tested here (extractant, diluent, flocculant, lubricating oil and acid mist suppressant) are currently used in industrial plants. The results indicated that only the flocculant and acid mist suppressant exhibit relevant negative impacts on the current efficiency and energy consumption. The current efficiency dropped from 93.6 % (organic-free solutions) to 86.0 % and to 92.8% in electrolytes containing 100 mg.L-1 of acid mist suppressant and flocculant, respectively. At this concentration, their addition to the electrolyte led to increases of the specific energy consumption in the order of 18 % (acid mist supressant) and 2 % (flocculant). Cyclic voltammetry showed that Ni nucleation occurs at more negative potentials at 50 and 100 mg.L-1 of these organics in the electrolyte, thus indicating an inhibition of the deposition process. The deposit quality decreased at the higher concentration of all organics, when more hydrogen pitting was observed. The acid mist suppressant caused delamination of the Ni deposit at 50 and 100 mg.L-1. The addition of 100 mg.L-1 of flocculant and acid mist suppressant to the electrolyte increased the nanohardness of the deposit around 31 and 72%, respectively. The increase in Ni deposit hardness may lead to a decrease in the material ductility, thereby affecting the stripping and cutting of Ni sheets. Our findings may be helpful since strong adverse effect of some organics that may be present in the electrolyte were identified, thus the industry can control and optimize the organic´s dosage in the corresponding operations.

Jan 1, 2016

By E. Stansfield

THIS test was described in a privately circulated First Progress Report on Slacking Characteristics of Coal, by A. C. Fieldner and W. A. Selvig, May 1, 1928. The test was described in detail in U. S. Bureau of Mines Report of Investigation 3055, in November, 1930.1 The test, in brief, is conducted as follows: A sample of freshly mined coal consisting of 18 to 25 pieces approximating 1 ¼ cubes, and weighing 500 to 600 grams, is taken for the test. The sample is subjected to a "blank sieving" of carefully regulated degree, on an 8-in. circular sieve with 0.263-in. square openings; and the undersize and oversize weighed. The oversize is placed on a sheet-iron pan and dried for about 24 hr. in an A.S.T.M. air-drying oven maintained at 30° to 35° C. through which a current of warm air is drawn. The sample is then cooled to room temperature and immersed for one hour in water at the same temperature. The water is then drained off, the sample dried for 24 hr. as before, cooled, sieved as before, and the oversize and undersize weighed. The percentage weight of the undersize, is calculated and reported as the first cycle loss. This loss, corrected by subtracting the percentage loss in the blank sieving, is termed the slacking index. The sample may be subjected to further cycles of wetting, draining, air-drying, sieving and weighing. In a letter (August, 1932) W. A. Selvig approved making the blank sieving on a duplicate sample, rather than on the sample used for the test, where sufficient coal was available. This method is now employed in these laboratories. The accelerated weathering test has been employed in the labora-tories of the Research Council of Alberta, at Edmonton, since 1928, but not found entirely satisfactory as repeat determinations with samples taken from the same or adjacent mines frequently showed serious differ-ences. Differences must be expected as the coal may vary in the seam, and the selection of a typical set of lumps approximating 1 ¼ -in. cubes

Jan 1, 1934

By Árpád B. Palotás, Adel F. Sarofim, John B. Vander Sande, Paolo Ciambelli, Lenore Rainey

"The evolution during oxidation of the internal structure of soot and carbon black particles was studied using high-resolution transmission electron microscopy (HRTEM) and an image analysis system. Increasing ordering to the carbon structure with increasing oxidation is observed. Measures of the increased order are increases in the fractional coverage of a cross section of the particles with a layered structure, a decrease in the mean interlayer spacing, and a decrease in the spread of the interlayer spacing. The changing structure of the carbon black impacts its properties, such as the rate of oxidation.There is considerable interest in the study of the structural changes of carbonaceous materials as a function of oxidation. Davis et al.1 measured the variation of carbon dioxide surface area of various coals as a function of residence time in a flow reactor. HRTEM measurements revealed that crystallite dimensions and interlayer spacings are altered by combustion. Ishiguro et al.2 showed that oxidation alters the structure of diesel soot. The aim of our current research is to develop a better understanding of the microstructural reordering of carbon blacks with implications to their properties. The carbon blacks used in this research have already been studied and their reactivities as a function of oxidation measured.3The methodology used in this work has already been described in detail elsewhere.4 This paper presents an application to quantify the structural changes of carbon black particles as a function of oxidation and graphitization. The technique used is based on the use of HRTEM (high-resolution transmission electron microscopy) and computational image analysis.It is well-known that carbonaceous materials like graphite, soots, coals, chars, etc., possess characteristic structural appearances which can vary from mostly random or amorphous to a perfectly ordered graphitic crystalline structure. The carbon structure has been variously described as turbostratic5 or as crumpled sheets6 to indicate that parallel layering, reminiscent of graphite, is observed over dimensions of nanometers but that these planes or crystallites show disorder over larger scales. The degree of order of such structures is strongly dependent on the thermal treatment of the material as well as the composition of the source of the carbonaceous material. The value of electron micros¬copy in studying the morphology of such materials has been well established,2,7,8 although only a few attempts toward quantification have been made.The sample observed was carbon black CB330 from De¬gussa. One set of carbon black samples were oxidized in a thermo-gravimetric analyzer (TGA) in air at 575 0C, so that the conversion varied from 0 to 96%. Another set of carbon black samples were graphitized (Graphpac-GB by ALLTECH) and then oxidized in the TGA at 680 °C until 92% burnout was reached. The latter samples are called GB 0% and GB 92%, respectively.For the HRTEM observation a small portion of each sample was ultrasonically dispersed in ethanol. The suspension was deposited dropwise on a copper TEM grid coated with a lacey carbon film. The examination of the samples was carried out on areas that extend over the holes in the supporting film in order to avoid interference from the amorphous carbon background film An oriented gold crystal was used as a calibration standard and subjected to the same techniques as the carbon black samples."

Jan 1, 1998

By Lifeng Zhang, Zineb Benouahmane, Yaqiong Li

Experimental oxidation tests at high temperature (1000-1200 °C) on SiC samples have been respectively performed under wet and dry air atmosphere for different holding times. The thickness of thermally grown oxide was experimentally measured by DEKTAK Stylus Profilometry. The results showed that the oxidation rate was increased with temperature and holding time, corresponding to a passive oxidation regime which led to the formation of SiO2 layer. The sessile drop method was employed in order to measure the contact angles between Si and SiC at high temperature. Contact angle can be varied from 39.6° to 75.6° by controlling the atmosphere. The deoxidation of the oxide layer and infiltration of liquid silicon caused a decrease in the contact angle.

Jan 1, 2016

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 G. W. Jones

THIS paper describes experiments in which eight test samples of gelatin dynamite were fired in three different types of apparatus and the quantity and composition of the gaseous products of detonation determined. The special dynamites were so prepared that the oxygen balance of the samples varied from -35.0 to +6.0 g. per 100 g. of explosive, including the wrapper. By means of this graded series of explosives, the relation between oxygen balance and gaseous products of detonation could be studied explicitly. The effect of varying oxygen balance on explosive strength has-been discussed in another paper.1 The apparatus employed in the work described in the present paper included (1) the Bichel gage, a steel bomb of 15-1 volume; (2) the Crawshaw-Jones confined detonation apparatus, a steel cannon from which the explosive is fired into a pipe of 904 volume; and (3) the Hercules tank, an apparatus in which the explosive is confined in a quartz block which is placed in a steel tank of about 4500-1. volume. A full description of the apparatus is given later. VARIABLES AFFECTING COMPOSITION OF DETONATION PRODUCTS The character of the detonation products of commercial explosives is governed in part by the same factors that affect the combustion products from explosive mixtures of air with gases or vapors. In either case, combustible materials-namely, carbon, hydrogen, and sometimes sulfur-are present and combined variously. In an exploding gas mixture the combustibles are oxidized by oxygen in the admixed air, whereas with explosives the necessary oxygen is provided by oxygen-carrying materials in the explosive ingredients.

Jan 1, 1928

By G. W. Jones

THIS paper describes experiments in which eight test samples of gelatin dynamite were fired in three different types of apparatus and the quantity and composition of the gaseous products of detonation determined. The special dynamites were so prepared that the oxygen balance of the samples varied from -35.0 to +6.0 g. per 100 g. of explosive, including the wrapper. By means of this graded series of explosives, the relation between oxygen balance and gaseous products of detonation could be studied explicitly. The effect of varying oxygen balance on explosive strength has been discussed in another paper.1 The apparatus employed in the work described in the present paper included (1) the Bichel gage, a steel bomb of 15-1. volume; (2) the Crawshaw-Jones confined detonation apparatus, a steel cannon from which the explosive is fired into a pipe of 90-1. volume; and (3) the Hercules tank, an apparatus in which the explosive is confined in a quartz block which is placed in a steel tank of about 4500-1. volume. A full description of the apparatus is given later. VARIABLES AFFECTING COMPOSITION OF DETONATION PRODUCTS The character of the detonation products of commercial explosives is governed in part by the same factors that affect the combustion products from explosive mixtures of air with gases or vapors. In either case, combustible materials-namely, carbon, hydrogen, and sometimes sulfur-are present and combined variously. In an exploding gas mixture the combustibles are oxidized by oxygen in the admixed air, whereas with explosives the necessary oxygen is provided by oxygen-carrying materials in the explosive ingredients.

Jan 1, 1928

By Hui-Gai Li

The fine Ti oxide inclusions precipitated during solidification are favorable for intragranular ferrite nucleation. The oxygen content before solidification affects the composition and size of inclusions. The composition of precipitated inclusions in Mn-Ti alloyed steel was studied by means of thermodynamic calculation and experiment in this paper. The micro-segregation of Mn, Ti and O during solidification was considered in calculation and unidirectional solidification apparatus was employed in experiment to ensure that alloy elements diffused along solidification direction. The results showed that: inclusions are mainly Ti oxide when oxygen content is 10ppm; they are Ti oxide and Mn-Ti oxide when it is 20ppm; Mn-Ti oxide dominates when it is 30ppm. With the increase of oxygen content, the size of inclusions increases. The maximum oxides size is about 3µm from statistical results of experiment.

Jan 1, 2008

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 corresponds 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 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 Y-B Kang, J H. Park, J Park

In order to understand the effect of oxygen injection into the molten metal on the valuable metals (VM) recovery and interfacial phenomena, several high-temperature experiments were conducted using a high-frequency induction furnace with a quartz tube as the reaction chamber at 1673 K. Copper-based waste printed circuit board (PCB) that contains some impurities was selected as the end-of-life resource. CaO-SiO2 based pre-fused slag and oxygen gas were used in present works. The composition change and microstructure of the samples were analysed. As oxygen was injected into the system, impurities were rapidly removed. After the removal of impurities, continuously injected oxygen lowered interfacial tension between liquid slag and liquid metal. Lowered interfacial tension induced Cu loss into the slag.

Aug 21, 2024

By Florian Kongoli

The optimal operation of the blast furnace depends considerably on the properties of the sinter fed into the furnace. As a result, the optimization of the sintering processes has a direct effect on the overall effectiveness of the iron making processes. In order to produce a good sinter special care needs to be taken in order to assure it has a good permeability and reducibility and it is able to retain these properties for a certain time. If the sinter starts to melt down early in the upper part of the blast furnace, where its solid state reduction is essential, permeability decreases, the gas channels get blocked, reductibility diminishes and serious problems may also follow. Among the factors that influences the above mentioned sinter properties are the oxygen potential and fluxing components. Nevertheless, their effect on the phase relations during sintering and sinter reduction conditions has not yet entirely clarified and confusion exists in literature. This quantification becomes even more important today where many new minor components such as Al2O3 and MgO enter the sinter through raw materials. This work quantifies the effect of oxygen potential and fluxing components such as alumina and magnesia on the liquidus and phase relations of the sinter primary melts in the iron rich portion of CaO-FeO-Fe2O3-SiO2 system at sintering conditions. This is carried out by the means of new type of industrial diagrams in the form of Fe/CaO vs. SiO2 that can directly help the optimization of the sintering processes.

Jan 1, 2006

By E. A. Morris

It has been shown that Alberta oil-sands fluid coke can be effectively used to reduce SO2 to elemental sulphur while simultaneously producing sulphur-impregnated activated carbon (SlAC). In the capture of mercury from industrial flue gases, SIAC has proven to be a highly effective adsorbent material. The current research aims at developing an existing SlAC technology to meet the needs of copper smelters for mitigating both mercury and SO2 emissions, while making elemental sulphur as a co-product. The challenge behind this undertaking is that these flue gases generally contain percent levels of 02 and H20 vapour (2-12%). The focus of this study is therefore on the feasibility of reducing SO2 using fluid coke under copper smelter flue gas conditions, as well as the optimisation of SIAC properties for capturing vapour phase mercury. It is hypothesised that mercury capacity is strongly affected by the 02 potential of the activation gas due to changes in surface sulphur types arising from different reduced sulphur species. To verify this, gas chromatography is used to analyse the reaction products while XPS and XANES will be used to describe the nature of sulphur on the SlAC surface. CVAFS analysis of mercury capacity will finalise the hypothesis assessment. Preliminary results indicate that 02 at 5% does not play a significant role in SSA or pore development. As expected, increased residence time contributes to SO2 reduction and elemental S yield.

Jan 1, 2007

By Thomas Crowe

Much has been written upon the precipitation of metals from cya-nide solution by zinc. We often read of the many factors that influence precipitation, such as zinc surface, purity of zinc, percentage of lead, temperature of solutions, strength of solutions in cyanide or alkali, etc. Little do we hear, however, of the part that oxygen plays in precipitation. Caldecott1 says: "As the dissolving of gold is essentially an oxidation process, so its precipitation is one of reduction." All who have studied or worked with cyanide solutions will agree that Caldecott&apos;s statement is true. In the cyanide work in the mills of the Portland Gold Mining. Co., we have always found oxygen to be the greatest enemy to precipitation. OXYGEN ANTAGONISTIC TO GOOD PRECIPITATION A few years ago, while making some experiments on the effect of pressure upon the dissolving rate of gold front our ores, to prove a point, I made some bottle tests under vacuum. The results were surprising, and showed that under vacuum practically no gold dissolved, which confirmed my belief that Elsner&apos;s equation was true and also led me to investigate the amount of dissolved air carried by solutions at atmos-pheric pressure. The experiment consisted in partly filling an acid-bottle with mill-solution and connecting it by a rubber hose to a vacuum pump. When the vacuum was suddenly applied, a cloud composed of. thousands of small air bubbles rose out of the solution, showing qualitatveily the . amount of dissolved air that was contained in the solution, and also proving that the relief of atmospheric pressure on the solution permitted this dissolved air to escape.

Jan 8, 1918

By H. M. O?Harra

Experiments have shown that the use of enriched air would be of particular benefit in the roasting of zinc ores for the manufacture of sulfuric acid. Enriched air increases capacity of furnace, decreases fuel consumption, and increases SO2 content of roaster gas. THE work here described had for its purpose the procuring of data from which some quantitative estimate might be made of the results obtainable by using oxygen-enriched air in roasting zinc ores on a commercial scale. The principal metallurgical advantages of using enriched air in roasting zinc ores would be: 1. The rate of roasting would be increased, with consequent gain in the capacity of the roasting furnace. 2. As less air would be required for roasting, the volume of hot gases leaving the furnace and the heat carried out of the furnace as sensible heat in these gases would be less per ton of ore roasted; partly for this reason and partly because of the increased quantity of heat generated in the furnace by the larger amount of ore that could be roasted, the consumption of fuel by the furnace would be lessened; and by the use of air sufficiently enriched with oxygen the necessity of using fuel might be entirely obviated. 3. Roaster gas having a higher SO2 content could be produced; this would make possible greater capacity and more economical operation of the sulfuric-acid plant. Certain phases of the application of enriched air to roasting can be worked out only by experimenting with a furnace of commercial, or at least semicommercial, size. Thus the precautions necessary to secure proper distribution of heat in the furnace;1 the volume of enriched air,

Jan 3, 1924

By O?Harra B. M.

THE work here described had for its purpose the procuring of data from which some quantitative estimate might be made of the results obtainable by using oxygen-enriched air in roasting zinc ores on a commercial scale. The principal metallurgical advantages of using enriched air in roasting zinc ores would be: 1. The rate of roasting would be increased, with consequent gain in the capacity of the roasting furnace. 2. As less air would be required for roasting, the volume of hot gases leaving the furnace and the heat carried out of the furnace as sensible heat in these gases would be less per ton of ore roasted; partly for this reason and partly because of the increased quantity of heat generated in the furnace by the larger amount of ore that could be roasted, the consumption of fuel by the furnace would be lessened; and by the use of air sufficiently enriched with oxygen the necessity of using fuel might be entirely obviated. 3. Roaster gas having a higher SO2 content could be produced; this would make possible greater capacity and more economical operation of the sulfuric-acid plant. Certain phases of the application of enriched air to roasting can be worked out only by experimenting with a furnace of commercial, or at least semicommercial, size. Thus the precautions necessary to secure proper. distribution of heat in the furnace;1 the volume of enriched air; and the proportion of oxygen in this air, necessary to give the desired increase in roasting capacity of the furnace and in SO2 content of the roaster gases;; and the most desirable frequency of raking, thickness of

Jan 11, 1924