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By R. G. Robins

Metal separations based on the selective precipitation of phosphates have a potential application in many hydrometallurgical processes. This paper reviews the literature on the solubility of a number of both divalent and trivalent metal phosphates and presents the result of some additional experimental measurements. The systems examined have been modelled to obtain free energy of formation data for the various species. Computer generated solubility diagrams which are described can be useful in predicting a variety of metal separations.

Jan 1, 1991

By T. Nagano

Mitsubishi Metal Corporation started the development work of a new process for continuous production of copper in 1961. After a series of experimental and semi-commercial operations, the first commercial plant of the Mitsubishi Continuous Copper Smelting and Converting Process was put into operation in March, 1974. The new plant, which has a design capacity of 4,000 metric ton copper per month, was built within the premises of Naoshima Smelter, replacing the old No.1 reverberatory smelter there. The SO2-rich exhaust gas from this new plant is blended with the off-gas of the No.2 reverberatory furnace for production of sulfuric acid and the overall emission of sulfur at Naoshima has been greatly reduced. The operation of the continuous plant has been satisfactory and several advantageous features of the Mitsubishi Process have been proven on a commercial scale. This paper first gives a brief description of the history of the development work and the characteristic features of the process. The paper then describes the new commercial plant and operating data obtained so far.

Jan 1, 1976

By Shadia J. Ikhmayies

Zinc oxide (ZnO) flowered-fibrous micro/nanowebs were produced as thin films on glass substrates at 350 °C using the low cost spray pyrolysis (SP) method. The films were characterized using the XRD diffraction, scanning electron microscopy (SEM), and X-ray energy dispersive spectroscopy (EDS). Hexagonal structure was confirmed from X-ray diffractogram, which showed preferential orientation along the (002) line. SEM images showed two dimensional flowered-fibrous micro/nanowebs, and EDS elemental analysis revealed the presence of chlorine in the films in addition to zinc and oxygen. The obtained morphology is important for optoelectronic device industry and solar cells, where it provides large surface area that helps light harvesting.

Mar 1, 2018

By G. L. Liu

"Deformation Banding ( DB ) in cold rolled mild steel has been experimentally established by microstructure investigation. Deformation banding model includes such deformation mode when it is applied to rolling texture simulation. The cause for the occurrence of deformation banding is the reduction of the total work for plastic deformation through a relaxation of the deformation constraints. In the first DB model, all grains are assumed to band from the first deformation step. Such an unrealistic assumption has been eliminated in the new model by the introduction of a banding criterion based on an energy minimizing approach. The prediction is closer to the measured texture by applying banding criterion and setting critical resolved shear stresses (CRSS) ratio for { 110 } and { 112 } slip modes to 0.85.IntroductionBased on the continuum theory of plastic flow and deformation mechanism of crystallographic dislocation slip, Taylor's FC ( Full Constrain ) theory [1] has been widely used in texture modeling. As the process of cold rolling of sheet materials produces a microstructure consisting of elongated or equiaxed flat grain or cell, the ""lath"" and ""pancake"" relaxed constraints ( RC ) models [2, 3] were introduced as the successful improvements over the classical FC model. It has been also recognized that crystals may split into different orientations during deformation and the term deformation banding is used to describe such deformation processes [4, 5]. Lee et al. [6, 7] pointed out that the success of the RC theory in predicting textures depends on the physical processes of deformation banding. They developed so called Deformation Banding ( DB ) model by considering DB in the longitudinal plane to be accounted for by the RC method and allowing DB in the rolling plane. DB model was applied to simulate the texture development in bee case [8], the predicted bee rolling textures are in reasonable agreement with the measured textures. In the first DB model, however, all grains are assumed to band right upon the first deformation step. A banding criterion was formulated [7] which states that DB will occur if the work used in DB model is less than that in RC model. Such criterion has been incorporated into the original DB model for texture simulation and is referred to as DBC ( Deformation Banding Criterion ) model."

Jan 1, 1998

By John W. Lund

The Geo-Heat Center has been investigating the utilization of waste silica from the Cerro Prieto geothermal field for several years. The main objectives of the research were to com-bine silica with various additives to (1) form bricks for low cost housing, and (2) to produce a suitable road surfacing material. The various additives that were tested included hydrated lime, portland cement, plastic fibers, asphalt cement and emulsified asphalt. The silica-cement combination produced the strongest bricks and had the best weather resistance, whereas, the silica-lime combination produced the bricks with the lowest thermal conductivity and specific gravity density. The addition of plastic fibers to the silica-lime mixture improved both strength and weather resistance. The combination of asphalt and silica is not suitable as a road surfacing material, however, silica-cement appears promising.

Jan 1, 2006

By Michael J. Nicol

Growing environmental and occupational safety concerns about the use of cyanide in gold processing has increased the interest in more acceptable alternatives. The most likely of these is thiosulfate. However, the thiosulfate process lacks a proven in-pulp method of recovering the dissolved gold, because activated carbon is not effective for the absorption of the gold thiosulfate complex .. Anion exchange resins do offer a possible route for in-pulp recovery. This paper describes work aimed at the evaluation of the effectiveness of commercially available anion exchange resins for the recovery of gold from thiosulfate leach liquors? and pulps. It has been found that strong-base resins are superior to weak-base resins in that they have a larger capacity, which assists in reducing the competition from other anions within a leach solution. Further studies with a selected commercial strong-base resin have shown that competing polythionateanions (particularly tri-and tetrathionate). Lower the maximum possible gold loading but that gold is selectively recovered over other base metal anions in solution. Kinetic experiments found that while? competilig anibns did not affect the initial rate? of gold loading it was important to minimise the contact time of the resin in solution so to prevent displacement of loaded gold by competing anions over longer times. A small-scale resin-in-pulp plant investigation showed gold can be recovered from a leach pulp by a strong-base resin to yield gold loadings of 3000 mg/L, barren pulp containing less than 0.05 mg/L of dissolved gold and. copper loadings of 500 mg/L. Loaded copper was displaced gold and at a loading of 2000 mg/L gold the copper loading was minimal «500 mg/L). The resin was found to recover gold adsorbed on the solids that would, otherwise have. reported to tails if a solid/liquid separation method were used. A patented two-step elution process in which copper and then gold are separately eluted from the resin is also discussed.

Jan 1, 1998

By Kongfang Feng, Fei Ruan, Zhiyu Liu, Jieyu Zhang, Xin Hong, Shaobo Zheng, Jixu Wang, Jinyin Xie

"Mixing phenomena in smelting reduction furnaces with asymmetric side blowing were studied in this paper. Mixing phenomena in a smelting reduction furnace was represented as the mixing time by electrical conductivity measurements. Experiments were performed in a water model under various operating conditions to determine the effects of horizontal angle, radial angle, inserting depth, flow rate of the upper and the lower side nozzle, the included angle between the upper side nozzle, and the lower side nozzle on mixing phenomena in smelting reduction furnace. Comparing mixing time and mixing phenomena, the optimal conditions were obtained for an asymmetric side blowing process.IntroductionIn recent years, many countries have put forward development strategies for saving resources and environment-friendly, the development of various industries had to face its influence for resources and the environment .As we all know, the steel industry is a pillar industry of the global economy, in which ironmaking is an important part of it. In the modern ironmaking process, the blast furnace is regarded as the most important equipment and tool. But with the increasing scarcity of metallurgical coke resources and considering the environmental impact of such processes, metallurgists proposed the concept of smelting reduction. Smelting reduction processes to produce hot metal from iron ore and coal were being developed as a possible alternative to the traditional blast furnace. At present, a number of smelting reduction processes had been developed all over the world, they were mainly included COREX, HISMELT, FINEX, DIOS, etc."

Jan 1, 2012

By Chuandong Wei, Mao Chen, Baojun Zhao, Zhixiang Cui

The first bottom blown copper smelting furnace (BBF) has been successfully operated for 10 years at Dongying Fangyuan Nonferrous Metals. In addition to many advantages of the BBF reported previously, stable operation with spinel-containing slags enabled the BBF refractories to achieve three-year campaign life. Understanding of the degradation mechanisms of the magnesia-chromite refractory will be able to further prolong the service life of the refractories and develop new refractories. In the present study, the post-mortem refractories were collected from different locations of the BBF during the annual maintenance. It is the first systematic study for the used refractories of a BBF. The phases present in the refractories and their compositions have been determined by Electron Probe X-Ray Microanalysis. The degradation mechanisms of the refractories are discussed based on the analyses. The results will be used to optimize the operation and select proper refractories in the furnaces.

Mar 1, 2018

The merging of flash smelting with spray converting in one single furnace is proposed as a continuous copper making process. The proposed process is expected to produce blister copper, clean slag and gas with high sulfur dioxide concentration. Some high grade matte is an intermediate product recycled within the proposed furnace, spray-atomized and converted. The thermodynamic equilibria of the simultaneous oxidations which take place during copper smelting and converting are discussed in order to establish the gradient of oxygen potential along the furnace required for smooth operation. The proposed process is a dynamic system designed to reach equilibrium only close to the slag skimming end of the furnace. The process feasibility is based on the predesigned significant difference between the rates of converting reactions in a finely dispersed system and the rates of deconverting reactions between immiscible liquid phases of restricted interface area. The converting of small stationary droplets of matte, in a silica saturated system, was studied in the laboratory for extremely short oxidation times (10 to 120 seconds). These experiments led to some interesting observations on reaction mechanisms and kinetic trends. The droplet size and the matte grade affected very strongly the oxidation rate and the proportion of the different products obtained.

Jan 1, 1976

By T. Shibasaki, S. Kamio, K. Kanamori

"Mitsubishi Process has been proven through fifteen years operation to be highly productive, cost efficient and easy to abate environmental requirements. However, in order the process to remain competitive from now on, it should also be adaptable to a variety of varying conditions. Various test works have been conducted from such a stand point of view and some of the new concepts have been implemented to the actual operation.The paper discusses the adaptability of the process to the change of concentrate grade with respect to copper and also impurities, acceptability of the secondary materials and the potential to increase unit capacity. IntroductionThe first commercial plant of Mitsubishi Process with 48,000 mt copper annual capacity started its operation at Naoshima Smelter of Mitsubishi Metal Corporation in 1974, and the second plant with 65,000 st annual capacity started in 1981, at Kidd Smelter, Timmins, Ontario, now Kidd Creek Division of Falconbridge Limited 2. These plants have increased their capacities to 90,000 mtpa respectively by adding oxygen and acid plant capacities while maintaining the original furnace design uncharged. Thereby both smelters have established more cost efficient operations. (3), (4)Mitsubishi Process applies so-called multi-furnace continuous system. Figure 1 shows conceptual flowsheet. Backgrounds that required and justified the development of such system are as follows:"

Jan 1, 1988

By Jie Li, Wenzhou Yu, Xuewei Lv

An efficient enrichment of primary silicon from the Al–Si melt can be beneficial for the Si purification and the cost reduction of the solvent refining process. In this paper, an alternating magnetic field was used to enhance the mass transfer and promote the crystal growth of primary silicon during the directional solidification of hypereutectic Al–Si alloy. The results show that the growth rate and morphologies of Si crystals changed continuously along the directional solidification direction. With the decreasing of Si content in the melt and the weakness of the electromagnetic stirring, the crystal growth rate of primary silicon gradually decreased and the Si morphologies changed from planetocellular ,cellulardendrite, and columnardendrite, respectively. This provides a deeper understanding of the Si crystal growth during the electromagnetic solidification, which will be good for achieving a high-efficiency enrichment of primary silicon in Al–Si melt.

Mar 1, 2018

By Fuming Wang, Xi Chen, Shuai Liu, Changrong Li, Dan Wu, Yaxu Zheng

The effects of B content and austenitizing temperature on hardenability and toughness of Cr–Mo alloy steel have been studied. The results show that the hardenability is deteriorated with increasing B content and austenitizing temperature. With increasing temperature, more and more B containing particles were dissolved in austenite and increase the amount of B atoms segregating at grain boundaries. Moreover, the coarsening grains reduce area of grain boundaries and also increase the amount of B atoms at unit grain boundary, excessive B atoms segregating at grain boundaries promotes precipitation of M2B, which accelerates ferrite nucleation and reduces hardenability. The main elements in M2B phase are Fe, Cr, Mo and B. The B atoms segregating at grain boundaries during austenitizing promote precipitation of M2B during tempering which deteriorate toughness significantly.

Mar 1, 2018

By Wangzhi Zhou, Huasheng Chen, Bowen Li, Meng Liu, Mingsheng He, Long Zou

Steel slag is an inevitable by-product from a steelmaking furnace such as a converter, an open-hearth furnace or an electric arc furnace. The yield of steel slag increases with the sharp rise of steel production. Utilizing the slag effectively and comprehensively is one of the important tasks to promote the development of iron and steel industry in China in a sustainable and efficient way. In this study, hot-poured steel slag from a converter was used to prepare ceramics by mixing with fly ash, microsilica, and quartz. After heating at 1100–1200 °C, the ceramics were well sintered. XRD revealed that multiple crystalline phases coexisted in the glass-ceramics, and the main crystalline phases were diopside and anorthite. SEM observation indicated that there was a plate-columnar composite structure in the ceramics. Reaction mechanisms were discussed.

Mar 1, 2018

By Hong Peng, James Vaughan

Thermal activation of bauxite has been proposed to enable bauxite dissolution at a reduced digestion temperature and also to reduce the organic content in the liquor. Research has been carried out on phase transformation of its main hydroxide components (gibbsite, boehmite and kaolinite) during calcination. However, there is limited information available on phase bauxite phase transformation during thermal activation. In this study, two bauxite ore samples were heated from 25 to 700 °C at a rate of 50 °C/min while monitoring the phase transformation using Rigaku in situ XRD. Different phase transformation pathways for gibbsite in the bauxite compared with pure gibbsite was observed. Boehmite and kaolinite in bauxite behaved similarly to their pure phases. The temperature of phase transformation depends to some extent on the bauxite sample. Samples were also characterised by scanning electron microscopy (SEM) to reveal changes in the microstructure.

Mar 1, 2018

By Liping Gu, Gordon A. Irons

"A 1/3 scale ""thin-slice"" model of an electric arc furnace was developed so that gas could be injected to simulate foaming gas evolution. The influence of arc jets, oxygen lancing and bottom bubbling was also simulated. Liquid velocities were measured by a white light particle image velocimetry system. Numerical simulations of some of these effects were made using commercial CFD packages. Comparisons with measured results show that considerable care is required to select the appropriate model and to interpret the computational results.INTRODUCTIONDuring recent years electric arc furnaces (EAF) have captured a significant share of steel production, partially due to increased productivity through the introduction of advanced technology such as oxygen injection, slag foaming and long-arc operation, process automation and post-combustion. However, systematic analysis of the process and these effects on heat transfer and fluid flow in the furnace is still in its infancy. Most investigationsl1 6l have been restricted to a specific application such as oxygen lancing or bottom stirring. In addition, it is very difficult to make comparisons between these computed results and experimental/industrial results. In this work a 1/3-scale ""thin-slice"" model of Dofasco's 190 ton EAF was built. The fluid flow in the bath due to the arc jets, bottom stirring, oxygen lancing and CO evolution was simulated. The velocity distributions in the bath were measured using Particle Image Velocimetry (PIV) System. In addition, numerical simulations of bottom stirring and CO evolution were carried out using two commercial CFD packages (Fluent and Phoenics). The objective of this work is to validate the mathematical models so that they can be applied to the full-scale furnaces."

Jan 1, 1999

By María Guadalupe Sánchez-Loredo

Silver from nitrate aqueous solutions was extracted by commercial organophosphorous extractants (tri-n-butylphosphate, Cyanex 471x, Cyanex 301 and Cyanex 302). Quantitative silver extraction was obtained using the Cyanex reagents. After loading, aqueous solutions of several reducing reagents were used to prepare fine silver powders by reductive stripping. Only both extractants Cyanex 471x and tri-n-butylphosphate (TBP) could be reductive stripped and regenerated by aqueous solutions of ascorbic acid, and Cyanex 471x was decomposed to the corresponding phosphine oxide by using sodium borohydride as reducing agent. Silver was recovered as fine particles, which were characterised by means of scanning electron microscopy (SEM). Micrographs showed that the powder size and morphology were directly affected by the composition of the applied organic phases and aqueous reducing media.

Jan 1, 2003

By Shengli Wu, Binbin Du, Mingyin Kou, Laixin Wang, Kai Gu, Shun Yao, Heng Zhou

Coke plays an important role on the actual blast furnace production (BF), and its quality significantly influences the BF ironmaking process. In this study, the effects of physical properties, chemical composition and high-temperature properties of coke on main technical indexes of blast furnace were investigated. Some coke indexes were defined to evaluate the coke quality. The main technical indexes of BF include production, quality of HM, and fuel consumption. The quantitative relationship between coke quality and main technical indexes of BF were obtained after a series of statistical analysis. What’s more, the effect of these coke quality indexes on blast furnace smelting process was also explored, and all the relationships obtained from the analysis will provide a theoretical basis for the appropriate use of coke in blast furnace. The most reasonable range of coke quality indexes can be determined combining with the actual production as well.

Mar 1, 2018

By Maryam Ghodrat, Bijan Samali

Disposal of waste syringes in a safe and eco-friendly way has been an issue of considerable scale for decades. The generated amount of waste syringes has escalated with the rapid growth in population and wide acceptance towards single-use medical devices. Some hospitals have their own on-site incinerators ,but recent tightening of air quality regulations and landfill levies led to the closure of manyon-site incinerators. The solution to this problem implicates the development of an environmentally-sound method that would employ these waste materials. This work investigates a thermodynamic modelling approach for incineration treatment of waste plastic syringes in Electric Arc Furnace (EAF) steelmaking. Mass balance was obtained from HSC Chemistry thermochemical package. The results indicate that the rate of iron oxide reduction in the slag is higher when coke is partially replaced by waste plastic syringes. Furthermore, the amount of dust and stack gas emission was reduced by around 0.4% and 1.25% respectively by replacing 20%-weight of pure coke with waste plastic syringes. The study demonstrates part of the coke can be successfully replaced by waste plastic syringes in electric arc furnace to provide additional energy from combustion without affecting the main process.

Mar 1, 2018

By J. -E. Eriksson, L. Hupa, T. Khazraie

With increased co-firing of coal and different biomasses in power plants, there is a growing need to study and characterize the produced, often heterogeneous ashes and to assess their utilization as secondary raw materials. In this work, we compare different methods for characterizing the ash compositions. These methods include scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDS), X-ray fluorescence (XRF) and inductively coupled plasma emission spectroscopy (ICP-OES). The content of carbonaceous residues in the ashes was measured with CHN Sanalyzer. The methods and the pretreatment required for each of the analysis were studied in detail for three ashes: (1) coal, (2) peat and wood, (3) peat and wood residue with dolomite addition. The limitations of each method will be discussed. This work gives guidelines for selecting a rapid and reliable method for analyzing the suitability of the ash for a particular application.

Mar 1, 2018

By Ryo Kawarabuki, Atsushi Shibayama, Masato Kosugi, Masanobu Fujita, Kohei Mitsuhashi

An investigation on improving copper and iron recovery by removal of organic carbon and carbonaceous gangue mineral through flotation was carried out. The ore contains chalcopyrite and bornite as valuable minerals, and dolomite and calcite as carbonaceous gangue minerals. The chemical composition of the ore indicates that grade of 2.08 and 5.37 mass% for copper and iron respectively, while carbon was 3.70 mass%. The total organic carbon in the feed was recorded as 2.02 mass%. The presence of these gangue minerals is detrimental to copper and iron recovery during flotation. Therefore a two stage flotation study was carried out to remove hydrophobic carbon and carbonaceous material from ore and to improve copper and iron recovery. The objective of the study was to find effective and selective flotation conditions which can eliminate gangue minerals from valuable minerals and improve quality (grade) and recovery of copper and iron. The obtained results could be used to develop a flotation circuit for recovering copper and iron from carbonaceous sulphide ores.

Mar 1, 2018