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By R. H. Rubisov

Sulphuric acid pressure leaching of nickeliferous laterites has attracted considerable attention from the nickel industry during the past five years. The process is especially advantageous for limonitic laterites that mostly contain goethite, because iron precipitates releasing acid and thus rendering low acid consumption. It is also applicable to mixtures of limonites and saprolites, although at higher acid consumption due to magnesium. Effective process design requires the solubility of metals that precipitate during the process to be known. In the present work, determination of metal solubilities is based on a simple speciation program that assumes the presence of only one dominant complex for each metal. The thermodynamic data for the precipitation reactions are extracted from high-temperature experiments with monometallic systems published previously. The validity of the approach is then tested against mixed bimetallic systems, and finally applied to calculate the solubility of aluminium, iron and magnesium in laterite leaching effluents "at temperature". In both cases of limonitic feed and limoniticfsaprolitic blends, the prediction closely follows metal solubilities measured experimentally at temperatures from 230 to 270°C and at terminal he acidities ranging from 10 to 75 g/L.

Jan 1, 1999

By John R. Turney

The success of the Mclaughlin acid pressure oxidatiun process has proved that a complex hydrometallurgical process can be an economically viable means of treating refractory gold ores. Homestake's Mclaughin acid pressure oxidation process was commissioned in August 1985 and ts currently operating at design tonnage of 3,000 tons per day. Mineralogical and process studies on the operating plant are discussed to show the improved understanding: of the process and its future applications. These studies are also compared with the initial process development work, thus illustrating the success of the initial scale up considerations.

Jan 1, 1989

By Derek J. Fray

Electric arc furnace dusts, especially those containing zinc ferrite, are notoriously difficult to process to give valuable products and non-toxic residues. The ideal process would remove and recover the toxic non-ferrous metals as pure metals, of commercial value, and non-toxic residue which can be used as a raw material in the steel industry. From an examination of the thermodynamics of the oxides and chlorides of the various elements in the dust, it is apparent that the chlorides of the toxic non-ferrous elements are more stable than the oxides while the reverse applies to the ferrous elements. This offers the opportunity for a complete separation of the zinc, lead and cadmium from the iron oxide. Results are presented for the chlorination of electric arc furnace dusts under oxidising conditions and the subsequent treatment of the chlorides to recover the pure metals and chlorine which can be recycled back to the reactor.

Jan 1, 1994

By Suzie Poulin, N. Geoffroy, G. P. Demopoulos

Most metallurgical industries generate toxic waste that must be treated prior to being released to the environment. However, in a lot of cases, the waste materials are poorly characterized or the analytical results are not well interpreted. These shortcomings often result in the development of inefficient industrial procedures, thus causing economic waste and difficulty meeting environmental regulations. Fortunately, a wide range of analytical techniques are available to guide researchers and engineers into making sound process development decisions. In this work, an industrial selenium and mercury removal process is used as an example to illustrate the application of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) coupled with Energy-dispersive X-ray spectroscopy (EDX) and powder X-ray diffraction (PXRD) on solid waste. Furthermore, samples of analytical results are presented and interpreted and the modifications to the industrial process that resulted are explained. Finally, a brief description of the advantages and limitations of the aforementioned analytical techniques is given with an emphasis on industrial solid waste material.

Jan 1, 2011

By Fumito Tanaka

The Mitsubishi process is the sole pyrometallurgical process for the continuous production of blister copper from Copper concentrates and has been successfully operated around the world. The development of calcium ferrite slag (CaO-FeOx-Cu10), the so-called "C-slag", has enabled continuous converting from matte to blister copper in the commercial scale operations. Commercial interests in the slag led to many papers over the CaO-FeOx slag. However, Cu2O bearing slag has not been studied well due to experimental difficulties. The authors have quantified the thermodynamic properties of the CaO-FeOX-Cu2O system. The results have been utilized to analyze various issues related to the converting furnace, such as the magnetite precipitation from the slag or from blister copper and to develop better controlling criteria for the continuous converting operation. -

Jan 1, 2003

By László I. Kiss, Verena Mackowiak, Alexandre Perron, Dominic Toulouse, Alicia Liedtke, Sándor Poncsák

"Bubbles play a very important role in different metallurgical applications like for example in electrowinning. During heterogeneous nucleation, the maximal size of the bubbles growing at the nucleation sites as well as the nucleation frequency is determined by the so-called detachment condition. Detachment occurs when the external forces acting on the bubble exceed the retaining forces along the solid-gas-liquid triple interface line. The phenomenon depends strongly on the shape and orientation of the solid surface and on the nature and strength of the external buoyancy and drag forces. In the present study the detachment conditions of bubbles from downward facing horizontal and inclined plates were studied experimentally under the effect of gravitational and hydrodynamic forces. The results show the deformation of the bubbles under the effect of the external forces and the detachment conditions as function of the bubble volume.IntroductionIn heterogeneous nucleation bubbles are generated at the so-called nucleation sites along the solid-liquid interfaces. They continue to grow there and after they reached a certain size they detach from the solid surface and leave the nucleation site. This scenario is well known both in boiling and electrolysis. During the growth period a stable equilibrium exists between the forces that retain the bubble at the nucleation site and the forces that try to remove it. This equilibrium evolves with the increasing volume of the bubble to the point when the detachment forces overcome the retaining forces.The life of a single bubble generated by heterogeneous nucleation can be divided into two periods separated by the detachment - or in other words by the departure - of the bubble: first the growth at the nucleation site and then the movement away. The knowledge of the detachment conditions makes possible the determination of the maximal volume of the bubble at the nucleation site that, in tum, makes possible the determination of the nucleation frequency. This is why so many researches have been directed toward the clarification of the details of the bubble detachment in the past decades. The equilibrium between the attaching and separating forces depend on the presence of body, surface and flow induced forces in the liquid, on the geometry and orientation of solid surface, on the properties of the solid-liquidgas system etc."

Jan 1, 2004

By Donald W. Trepp

Colony Development Operation is a joint venture currently consisting of four active members; The Oil Shale Corporation (TOSCO); Ashland Oil Inc.; Shell Oil Company and Atlantic Richfield Company, operator of the project. The initial efforts on the Colony project began in the spring of 1965. Pilot mining and semi-works engineering programs continued, in phases, to completion in the fall of 1972 when commercialization of oil shale was deemed realistic. Since that time, Colony efforts have been directed toward evaluation of the data collected during the semi-works operation and in designing a commercial operation. In October of 1974, Colony announced: "because of economic and national energy policy uncertainties it was suspending plans to start construction of a commercial oil shale plant on private lands in northwestern Colorado, scheduled for spring of 1975."

Jan 1, 1975

By J. S. Kirkaldy

A theoretical procedure is demonstrated for calculating two-dimensional binary cellular single-valued interfaces and extended to triple-valued (remelt) shapes. The numerical calculations for the single-valued local equilibrium problem which yield unique shapes as functions of the supersaturation parameter a and the partition coefficient k are reviewed. The cell amplitude L and wavelength A scale identically as the inverse velocity to the 112 power and the aspect ratio r is a constant equal to 312, independently of a and k for a < 0.5.. For 0.5 < a < m, L, A and r decrease asymptotically to zero indicating the finite amplitude nature of the instability at a = 1 and the existence of sub-marginal states which converge to a flat interface at a- m (Glv- m). Scaling comparisons between equilibrium single-valued and triple-valued and deep-rooted non- equilibrium cells are made.

Jan 1, 1992

By Yoon-Bong Hahn

A mathematical model has been developed to analyze and predict the reduction process of iron ore particles in a two-stage fluidized bed system. This model includes the effect of particle degradation to elucidate its effect on reduction of iron oxides. Although the particle degradation is dependent on kind of iron ores, it was found that eighty to ninety percent of overall degradation is occurred in the prereduction stage mainly due to thermal stress and volume expansion. The degradation of particles in the?final stage is not much, but is mainly due to interparticle collision and abrasion. It was also found that to obtain a target reduction degree, it is of great importance to control the bed temperature and the residence time of paarticles in R1 rather than in R2. Optimum range of residence time was 15-20 minutes in the prereduction stage; 30-35 minutes in the final reduction stage.

Jan 1, 1996

By G. Goodall, D. Mercier, M. Brochu, C. Kaplin

A nanostructured CoNiCrAlY coating was obtained by thermally spraying cryomilled feedstock powder using the high-velocity oxy-fuel (HVOF) process. The oxidation behavior of the nanostructured powder and coating were compared to their conventional counterparts by performing static oxidation tests at 1000°C for durations ranging from 1 to 96 hours. It has been found that oxidation of the conventional powder yielded a duplex oxide scale composed of an inner layer of Al2O3 and an outer layer composed of Cr2O3, NiAl2O4 and other spinels. Interestingly, oxidation of the as-sprayed nanostructured coating yielded a similar duplex oxide scale while oxidation of the polished coating resulted in a single Al2O3 layer. These findings indicated that surface oxide seeds act as nucleation sites for the growth of the mixed oxide layer. Also, it was determined that nanostructuring of the coating promotes the nucleation and growth of a single and adherent a-Al2O3 layer by increasing both the number of diffusion channels and the aluminum concentration at grain boundaries.

Jan 1, 2010

By Joshua C. Adams, Les Chernauskas, Edward L. Hajduk

"Drilled shafts are increasingly being used to support bridge and building foundations. Because these foundations usually carry very high design loads and often serve as non-redundant, single load carrying units, these foundation systems need a high level of quality control (QC) and quality assurance (QA) during construction. One such method for providing QC/QA is crosshole sonic logging (CSL) testing, in which ultrasonic signals sent across the drilled shaft concrete assess concrete quality.CSL testing is an effective tool to evaluate the integrity of the in-place drilled shaft concrete. While typically used to evaluate drilled shaft concrete after construction, CSL testing can also be used to evaluate drilled shaft repairs. This application can be difficult, given the variability of repair methods and material properties. CSL testing can also be adversely affected by the condition of the concrete/access tube bond, leading to false anomaly detection and/or inability to evaluate concrete integrity effectively. This phenomenon, called access tube debonding, is often located in upper portions of the drilled shafts where large changes in groundwater occur, such as within tidal zones.Two case histories showcase innovative uses of CSL testing to deal with consistent access tube debonding and to evaluate drilled shaft repairs.CSL OverviewCSL testing involves placing ultrasonic transmitters and receivers in access tubes installed in the drilled shafts prior to concrete placement. Concrete quality is assessed by examining the First Arrival Time (FAT) and relative energy of the signal sent between the transducers. If the distance between the access tubes is known, an apparent signal velocity (i.e., wave speed of the ultrasonic signal through the concrete) can also be determined and used to assess concrete quality.Common CSL testing practice consists of simultaneously raising the ultrasonic transmitter and receiver and recording the ultrasonic signals with respect to depth. This results in a 2D examination of the"

Jan 1, 2009

By S. Devereaux, P. Gover, S. Everett

Having real-time data of blast furnace burden profile with respect to burden height and temperature is critical to making informed decisions on blast furnace operation. Given the high temperature and gaseous environment within the blast furnace shaft, traditional instrumentation has been limited at providing the level of real-time feedback information needed to optimize blast furnace operations. Infrared thermal imagery technology provides non-contact temperature measurement across the entire burden profile, allowing for better understanding of the dynamic movement of the burden within the blast furnace shaft. This technology increases blast furnace performance by improving the decision-making process for hour by hour operations. This paper will discuss the development of incorporating infrared thermal imagery technology into the operating strategy of a lead blast furnace.

Jan 1, 2015

By Eugene Holman

UINQUESTIONABLY the petroleum industry not only can supply the world&apos;s present oil requirements but even can meet a considerable increase in demand if it should come. The United States produced last year 1 1/3 billion barrels of crude oil, or more than 60 per cent of the world&apos;s total. It could have provided more, if needed, because we has a large shut-in crude producing capacity. Our refining capacity of 4,500,000 0 barrels per day is more than 2 per cent above our average refinery run for 1940. Adequate crude supplies and manufacturing facilities also exist outside of the United States. Large crude reserves exist in South America, in Iran and Iraq, in Russia and Romania, in Sumatra and adjacent islands. The refineries of the Dutch West Indies, of Iran, and of the Netherland East Indies are well located in relation to crude reserves and world trade lanes. Furthermore, flexibility in the manufacturing facilities permits adjustment of yields to meet a considerable range in variations between demands for products. Only with regard to 100-octane aviation gasoline is there any apparent refinery problem. Even here so far as this country is concerned, additional refining facilities can be installed well within the time that would be required to turn out the airplane engines which will use this super fuel.

Jan 1, 1941

By Roy G. Mead

BECAUSE of its magnitude, and the type of occurrence, the deposit of boron minerals in the Kramer district, Kern County, California, is unlike any other in the world. Discovery of this vast deposit has brought about many changes in the borax industry, so a discussion of the geology, and the occurrence, would not be complete without a brief history of the development of the borax industry. Until the discovery of boron minerals in the desert regions of California and Nevada some seventy years ago, borax was imported from Tibet and India, principally for medicinal purposes, at almost prohibitive prices. Following the discovery of commercial deposits of boron minerals in California and Nevada, and the subsequent development of new uses for borax and boric acid, the consumption has steadily increased until today borax is used in some form or other in every household.

Jan 1, 1933

By Paulo Sérgio Moreira, Geraldo Lúcio de Faria, Rhelman Rossano Urzêdo Queiróz, Amanda Aparecida Fátima Arruda, Ana Cecília de Carvalho

O objetivo deste trabalho foi avaliar o desempenho em desgaste de camadas espessas de óxidos formadas na superfície do aço inoxidável ferrítico 410D após a sua submissão a tratamentos isotérmicos em atmosfera oxidante. O aço em questão foi estudado no estado de entrega e tratado isotermicamente nas temperaturas de 900°C e 1000°C por diferentes intervalos de tempo. O método de avaliação empregado foi o teste de desgaste micro-abrasivo do tipo esfera presa em placa. Com o desenvolvimento do estudo, foi possível executar análises qualitativas e quantitativas a respeito do comportamento em desgaste do aço inoxidável 410D em função de sua condição superficial, como oxidada ou não. Alterações microestruturais também foram consideradas na discussão dos resultados. Concluiu-se que a camada superficial de óxidos desenvolvida após os tratamentos isotérmicos possui boa aderência e tem potencial para aplicação como camada protetora do aço em aplicações onde a sua resistência ao desgaste seja requerida.

Oct 9, 2019

By Geoffrey A. Brooks, M Akbar Rhamdhani, Md Saiful Islam

A novel electrically-enhanced metal purification using slag has been developed. This was achieved by applying DC potential between liquid metal and slag phases. The concept was demonstrated through small-scale experiments at temperatures of 1500-1600oC for the removal of boron from Si-B melt using CaO-SiO2-16wt%Al2O3. Silicon (containing B) and slag were reacted in an alumina crucible in a resistance tube furnace. A circuit was produced by immersing graphite rods into the silicon bath and the slag layer. Electrical potential differences of up to 3.5 V were applied during the reactions. The reaction rates, the opencircuit voltages and short-circuit currents (in the case when the potential was applied) were then measured and determined for various slag to silicon ratio. It has been shown from this study that both the apparent rate and the boron partition ratio were increased by a factor of approximately 1.6.

Jan 1, 2014

By Rhulani F. Maluleke, Francis W. Petersen, John H. Marsh, Johann de T. Steyl, Allan Nesbitt

"Pressure leaching of chalcopyrite and nickeliferrous pyrrotite at temperatures between 105 and 200 ºC has been proposed as a potentially viable route for the extraction of mineral elements from sulphide concentrates. In general, these concentrates contain iron, and the economic success of the processes is partially dependent on the choice of the environmentally acceptable iron-removal technique. One of the most widely used methods for the removal of iron from sulphate liquors is precipitation as hematite, goethite, or jarosite. The nature of the iron precipitate formed dictates downstream dewatering and residue treatment and disposal options. However, a better understanding of iron precipitation under the defined process conditions would consequently be of benefit in process design and optimisation.This study investigated the precipitation of iron in the autoclave at temperatures between 105 and 200 ºC. The effects of temperature, acid concentration, iron concentration, and the presence of other metal cations on the nature and composition of the precipitates were determined."

Jan 1, 2003

By S H. Li, H Z. Gu, A Huang

High aluminium steel is a promising advanced steel known for its exception properties and holds significant economic and strategic importance. However, the CaO-Al2O3-SiO2 based slag with high alumina content reacts vigorously with alumina refractories during the smelting process at high temperature, seriously affecting the safe and efficient production of furnaces and resulting in the formation of Al2O3-MgO non-metallic inclusions within the molten steel. This is a bottleneck problem for high-quality steel refining, and the key reaction path during the corrosion remains unclear. The dissolution reaction mechanism of alumina refractories in high alumina CaO-Al2O3-SiO2 slags under a weak static magnetic field was investigated in this work, using high temperature laser confocal microscopy and in situ radiation spectroscopy techniques. The results indicate that the interaction between the high alumina slags and the alumina refractories is governed by free radical reactions. The dissolution of alumina forms AlO and AlO2 radicals. The reaction rate increases with the C/S ratio of the slag due to its low polymerisation. The reaction between non-bridging oxygen and AlO2 free radicals accelerates the generation of AlO and O2ꞏ- radicals. The reaction layer composed of calcium aluminate is formed through the recombination of AlO, Caꞏ+ and O2ꞏ- radicals. The weak static magnetic field induces the Zeeman splitting of free radical pairs and intersystem crossing occurs, promoting the formation of triplet free radical pairs through the hyper-fine coupling effect. The reaction can be significantly inhibited as the triplet free radical pair does not meet Pauli’s incompatibility principle. This discovery perfects the structure theory of molten slags with radicals and provides supplement to the design of the highly slag-resistant refractories, and provides the theoretical basis for the development of external field protection technologies for high-quality steel refining.

Jun 19, 2024

By Jinke Li, Fenghua Wang

"While coal fueling China's economic growth it has already been causing severe pollution and amounts of CO2 emission. How to make deep reductions in carbon emission is not only a huge challenge for the greatest consumer of coal, but also a revolution for China’s coal industry. The paper explores how to shrink CO2 emissions during the lifetime of coal. The paper points out that increase of coal mine efficiency and productivity, green mining, utilization of coal mine methane and environment-friendly disposal of coal gangue can reduce CO2 during coal mining; coal preparation and coal by wire can decrease CO2 during coal preparation and transportation; improving combustion efficiency, CO2 capture and storage (CCS) and coal transformation can lessen CO2 during coal utilization. The paper also points out that Circular Economy Park is a practical way to develop a low carbon economy for coal industry. An econometric model for total coal industry and each sector are constructed to measure carbon emissions based on CO2 equivalent emissions, then with detailed calculations, based on potential greenhouse-gas emission's reduction, a most likely low carbon roadmap of China's coal industry is depicted with scenario analysis method.Introduction Global warming poses a profound threat to humanity and the natural world and is one of the most serious challenges humankind has ever faced. According to the 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), global surface temperature increased 273.89 ± 273.33K during the 20th century (IPCC 2007). Increasing concentrations of greenhouse gases have caused most of the observed temperature increase since the middle of the 20th century (United States National Academy of Sciences 2008), and CO2 is the most important cause of global warming. In 2005, CO2 contributed 76% of global greenhouse gas emissions, CH4 contributed approximately 16%, N2O contributed approximately 6% and the combined F-gases contributed approximately 2% (IEA 2010). Among the many human activities that produce greenhouse gases, energy use is by far the largest source of emissions. Since 1870, CO2 emissions from fuel combustion have risen exponentially (IEA 2009). Of the three types of fossil fuels - coal, natural gas and petroleum - coal constituted only a quarter of the world total primary energy consumption in 2007. The situation is even more critical in China than in the rest of the world, as energy-intensive industrial production is growing rapidly, and large coal reserves exist in combination with limited reserves of other energy sources. The development and production of the coal industry provide stability in China's economic growth. There are more than 7000 coal enterprises in China; the coal enterprises are the main contributor to China's ""economic miracle""."

Jan 1, 2017

By F. R. Cattoir, R. E. Cumings

Columbium metal was electrorefined in a fused - salt electrolyte . Excellent results were obtained in lowering the impurity content in a 94 - percent columbium anode feed material to produce a 99.8- percent - pure metal . The reductions of the major impurities follow : Oxygen from 19,800 to 500 ppm , carbon from 9,700 to 25 ppm , iron from 9,200 to 630 ppm , nitrogen from 2,100 to 90 ppm , and silicon from 750 ppm to not detected . Columbium with a purity of 99.9 percent was produced from 99.5- and 99.8 - percent grades of columbium. The investigation was devoted to the evaluation of a fused - fluoride - salt electrolyte ( KF - NaF- K₂ CbF, ) for electrorefining columbium. The effects of the columbium concentration and the voltage upon the product's purity were investigated . The effect on the cathode current efficiency of ampere - hours of deposition and the formation of a dual valence state of the columbium was also investigated .

Jan 1, 1964