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By Alicia Esther Ares, Alex Iván Kociubczyk, Verónica Liliana Scheiber, Roberto Rozicki

In the present research the horizontal solidification of Sn-Zn eutectic alloys (Sn-8.9wt.%Zn) is performed, with two opposite senses of heat extraction. From the process of solidification, the thermal parameters (local solidification time, cooling rates and interphases velocities) and grain sizes from macrostructures obtained were determined. The presence of defects in the solidified samples was analyzed, observing that they occur largely in the collision zones of solidification fronts advancing in opposite directions in the samples.

Jan 1, 2016

By J. R. Wynnyckyj, R. Marr

Continuous measurement based on radiation pyrometry has often met with difficulties whose causes have been obscure. In this paper the experience gained with on-line pyrometry in utility and Kraft recovery boilers in the range 800-l400oC will be reported. It is shown that the inherent problems are best resolved by using a spectral pyrometer not sensitive to gas radiation. The radiation from the suspended particles thus provides the signal. It is further shown that the principle cause of difficulties is signal calibration drift caused by heat fluxes originating from surrounding surfaces and reflected by the particles to the pyrometer. Several examples are given how such problems may be resolved using process information and/or additional measurements, fed to and processed by and on-line microcomputer.

Jan 1, 1989

By Xiancong Zhao, Hao Bai, Qi Shi, Zhancheng Guo

Reducing electricity cost is important for energy intensive industries such as the iron and steel industry. With the implementation of time-of-use (TOU) electricity price, plenty of attention has been paid to the optimal management of byproduct gases. The time-of-use (TOU) electricity price is the practice of implementing different prices for different times of use. It is possible to reduce electricity cost by adjusting the amount of product gases stored or used for power generation throughout the day. In this paper, a novel mixed integer linear programming (MILP) model concerning the TOU electricity price is proposed to optimize byproduct gas use. Compared with previous models, this model considers the optimal load shift between gasholders and boilers under TOU electricity price. The case study of a steel plant demonstrates that the electricity purchase cost can be reduced by more than 30% after optimization.

Jan 1, 2016

By Hylton McWhinney, Doanh Tran, Jewel Andrew Gomes, George Irwin, Sameer Pallavkar, Md Islam, David Cocke, Mohammad Rafiqul Islam

"High-performance nickel-based nanocrystalline zinc oxide adsorbents have been prepared adjusting Ni/Zn mol ratio of 1 :5 by thermal decomposition, coprecipitation and sol-gel method for selective adsorption of thiophene in liquid hydrocarbon fuels at ambient temperature and pressure. To understand the nature of reactive adsorption of thiophene (C4H4S) on Ni/ZnO, the effect of preparation techniques, morphological and textural structure on the desulfurization activity was investigated. A model fuel (20 mL) consisting of pentane (C5H12) and thiophene was prepared and adsorption experiments were performed by a batch method under ambient conditions. The physicochemical behaviors of the fresh adsorbents were obtained using X-ray diffraction (XRD) with EDAX, scanning electron microscopy (SEM). The sulfur concentration in the mixture was monitored by UV-vis spectrophotometry. The adsorption reaction confirmed that ZnO played a crucial role in taking up S element to convert it into ZnS. The deposition of nickel on ZnO is an innovative approach which takes advantage of the selectivity of Ni towards S-species and the high adsorptive capacity of ZnO support.IntroductionLow temperature deep desulfurization of fuels via selective adsorption of sulfur compounds keeping coexisting aromatic hydrocarbons and olefins intact is receiving increasing attention in the research community worldwide in order to satisfy the upcoming environmental regulations and fuel specifications. The sulfur compounds in the transportation fuels is a matter of concern when global crude oil slate is becoming heavier and sourer and environmental restrictions on both the refining process and the refined products are becoming more stringent. According to the current refinery technologies, the sulfur content in refinery fuel is typically around 300-500 ppm by weight (ppmw) [1-3]. Starting in 2006, sulfur limits in highway diesel and gasoline were set to 15 ppm and 30 ppm, respectively. During combustion sulfur in the fuel are converted to toxic sulfur oxide (SOx) and contributes to air pollution and acid rains [ 4]."

Jan 1, 2011

By Robert Vidal

A model of the homogeneous chemistry and transport processes within the separator of a chrome-alum electrowinning cell is introduced, discussed, and compared to experiment. The influence of diffusion, electromigration, and convection are included; it is found that convection was the dominant mode of transport for the experimental conditions. Simulation results explain experimental observations concerning an apparent disappearance of dichromate ions produced at the cell anode. The relation between potential drop across the diaphragm and the current and fluid flow is also illustrated. The model is used to recommend future experimental and theoretical work.

Jan 1, 1994

By Tomas Astorga

APEC, the Asia Pacific Economic Cooperation is the forum of 21 countries having approximately 56% of the total world income, and over 45% of global trade. In 1997, APEC economies produced 67% of the world copper output, 55% of gold, and over 45% of other base metals. Mining in APEC captures more than 60% of the total mining investment in the world. New and emerging economies are now appearing in the demand scenery, such as China. New trends in the international environmental regulations are posing questions related to the use of copper in different industrial and consumption applications. These may have a strong impact on future trade of copper. New applications are also appearing based in new technology fields. The paper examines the growth potential of the copper market in main consumer ad highly populated economies of APEC, incorporating analysis of various interrelated factors. It also analyses the outlook of the copper supply. Its conclusions point to the need to implement demand outlook models. Finance and economic reforms will open important avenues for trade growth in basic metals, particularly copper. Changes in the consumption patterns of highly populated countries will add to better perspectives of copper demands. The recovery of a fast pace of economic growth in the APEC region will bring new demands for copper, especially as a consequence of high tech applications. More extended policies focused in the need for developing energy efficiency programs and schemes will add to this picture.

Jan 1, 1999

By Onwukamike, Onyedika G. O, Ogwuegbu M. O. C., K., Onyenehide C

A detailed mineralogical and elemental characterization of a lead (Pb) ore deposit from Ishiagu, Ebonyi State, Nigeria was carried out with XRD, SEM-EDX, and ICP-OES based mappingtechniques. The results show that the most dominant and valuable metal is lead (Pb = 95.02%, mass fraction). The main mineral is galena. Ilmenite and sphalerite occur as minors, which account for 2.71% and 0.80% respectively. Elements like Al, Ca, Mg, Ti, Na, Mn, Si and Sn occurred in trace amounts and are disseminated in the entire ore body.The surface and interrelations of the crystals were examined with x-ray mapping and the result shows the pattern of dissemination of the minerals within the ore body.

Jan 1, 2015

By Leizhang Gao, Zhengfeng Qu, Pingsheng Lai, Chenguang Bai, Meilong Hu

Since Fray-Farthing-Chen (FFC) Cambridge process was proposed in 2000 for electrochemical extraction of titanium from titanium oxide, a great quantity of research has been carried out to investigate the mechanism of the electro-reduction of the process. Results show that the intermediate products of perovskite phases are inevitable during the electro-deoxidation process. In this paper, a new perspective focus on the anodic behavior was applied. The behavior of the graphite anode with different times has been investigated. Although the main anodic process in the electrolysis is the oxygen evolution by means of the CO2. The interphases of calcium species appeared on the cathode are closely related with chlorine ions in the molten CaCl2. In addition, the released CO2 from the anode is related with the formation of CaCO3 which floated on the surface of the molten salt.

Mar 1, 2018

By Maria Leikola, Joseph Hamuyuni, Petteri Halli, Fiseha Tesfaye, Mari Lundström

In a race to save the planet of its rapidly depleting natural resources, the use of Secondary Raw Materials (SRMs) as replacements in several processes is currently intensively pursued. In fact, this is currently one of the European Union (EU)’s mandates. Valorization of SRMs is consistent with circular economy, where resource efficiency is maximized for the benefit of both businesses and the environment. In line with this mandate, this paper focuses on investigating process phenomena related to hydrometallurgical recycling of Electric Arc Furnace (EAF) dust. In the experimental study, selective dissolution of zinc and other metals is investigated to acquire a recyclable leach residue. Based on the experimental and theoretical investigations, zinc could be extracted from the EAF dust and a recyclable leach residue produced, having chemical composition suitable as a feed material into electric arc furnace.

Mar 1, 2018

By K. Osseo-Asare

Third phase formation, the separation of a solvent extraction organic phase into two liquids, is generally attributed to the limited solubility of the extracted complexes in the hydrocarbon diluents. Much of the research on third phase fomiation, therefore, emphasizes experiments designed to establish the stoichiometry of the species responsible for the limited solubility. This work offers a different approach, based on the recognition that the solvent extraction third phase, in fact, corresponds to the middle phase in a microemulsion fluid system. Using the tri-n-butylphosphate (TBP)-diluent-water-electrolyte system as a model system, current concepts of microemulsion phase behavior are utilized to develop a general framework for interpreting and predicting the patterns of phase behavior in solvent extraction systems.

Jan 1, 1999

By Cheng Yan, Yugang Li, Qian Wang, Lizhi Zhang

In continuous casting process, mold powder has lots of metallurgical effects, such as covering the molten steel to prevent liquid steel from oxidation by air, preserving heat for top layer liquid steel, lubricating initial shell and so on. However, mold powder also can deteriorate the quality of final products obviously after the entrapment of mold powder in steel. In the present work, based on the similarity theory the effect of technological parameters on mold powder entrainment was investigated by water model. Experiment was carried out in the water mold using oil and water to simulate slag and steel, respectively. The results showed that increasing casting speed increased the water-oil interfacial fluctuation and entrainment frequency; viscosity of oil also had a great impact on the interface fluctuation and entrainment; water-oil interfacial tension effect the entrainment while not changing the interfacial fluctuation; submergence depth had little impact on entrainment and interfacial fluctuation.

Jan 1, 2015

By Kandipati Sreenivasarao

Ion flotation is a promising separation process for continuously removing toxic metal ions from dilute process effluents. After treating the effluent with appropriate surfactant(s), the metal- bearing species adsorb onto the surface of rising gas bubbles and can be collected as foams. Suitable collectors have been identified for most of the elements of the periodic table. However, a better understanding of the thermodynamic, kinetic and engineering principles that determine the performance of ion flotation systems would facilitate commercial utilization of this technology. A model system of sodium dodecylsulfate-ethanol has been studied for the removal of Cu (11) from dilute solutions, using laboratory-scale flotation columns. This paper reports the effects of the air flow rate, solution height, foam drainage zone height and col1ector:metal ion ratio on the flotation kinetics, ultimate recovery of metal, flotation product grade, foam losses and effluent quality. Preliminary results for Pb (11) removal are also reported.

Jan 1, 1993

By Bing Ji Yan, Cui Wang, Ya Peng Zhang, Chuan Hui Li, Hong Wei Guo, Jian Liang Zhang

There are a lot of research of the chlorine element’s influence on blast furnace, and mainly pay close attention to the harm to gas pipes and equipment. There are three kinds of chloride in the blast furnace gas, including HCl, NH4Cl, and NaCl (or KCl, ZnCl, etc.). This paper mainly analyzes all kinds of phenomenon of the chlorine element overflowing blast furnaces in Jinan Steel, and puts forward some different viewpoints, which are that the chloride overflowing out of blast furnace in the types of HCl, NH4Cl, or NaCl (KCl) not only has much to do with raw materials of chlorine load level, at the same time with the blast furnace burden distribution. On this basis, comes up with countermeasures for the different situation, such as adjusting the burden distribution matrix to guarantee the central gas flow smooth and changing the kind of raw materials to reduce the chlorine quantity, which will be helpful to prevent the harmful influence of chlorine element.

Mar 1, 2017

By W. G. Davenport

Flash smelting is used. mainly for making molten Cu-rich matte* from fine Cu-Fe-S** flotation concentrates. It blows dried concentrate particles into a hot fumace, surrounds them with 01-rich gas and allows them to react. The results are: (a) partial oxidation of Fe and S from the concentrate (b) generation of heat (c) melting of the oxidized particles to form molten Cu-rich matte, ~65% Cu and Cu-barren slag, ~1 % Cu. The melted particles fall to the hearth of the flash furnace where they fonn matte and slag layers, The matte is tapped from the furnace and oxidation-converted to metallic copper. The slag is skimmed, treated for Cu recovery then stockpiled or sold. Figures 1.1 and 1.2 show industrial flash furnaces and the position of flash smelting in the coppermaking flowsheet. ,Fig. 1.3 shows the locations of flash furnaces around the world.

Jan 1, 2001

By W. G. Davenport

The flash furnace is used for smelting concentrate to (i) high-Cu matte and (ii) molten metallic copper. It is also used for converting solidified/crushed matte to molten metallic copper. This is flash converting. It consists (Table 20.1, Fig. 20.1) of: (a)tapping molten 65 to 72% Cu matte from a flash smelting furnace (b) granulating the molten matte to ?1/2 mm particles in a 103 m3/hour water torrent (c) crushing the granulated matte to 50 µm in a vertical roller mill (d)drying the crushed matte (e) feeding the dry particulate matte to a second flash furnace for oxidation converting to molten copper. In 2000, flash converting is being used by Kennecott Utah Copper (George, et al; 1995; Newman et al, 1998, 1999a,b). A second installation is being designed for the Chuquicamata smelter (www.outokumpu.com [October 12, 2000]), The potential uses of flash converting are: (a) as the second half of a flash smelting/flash converting coppermaking sequence (b) as a continuous converting alternative to batch submerged tuyere converting. This chapter uses our flash furnace matrix to determine the %O2-in-blast, industrial oxygen and oil requirements for converting solidified 65% and 72% Cu matte to molten copper. It then discusses choice of feed matte grade and other aspects of the process.

Jan 1, 2001

By S. H. Castro

In 1997 Chile was the world's largest copper mine producer with around 3.4 million metric tomes of copper. Conventional technology (conminution-flotation- smelting-converting-electrorefining) for copper sulfide ores was used. For copper oxidized ores hydrometallurgical processes (heap leaching-solvent extraction- electrowinning) were employed. Consequently, the most important waste effluents include flotation tailings, gaseous emissions, smelter slags, acidic and alkaline wastewater, electrolytic sludges, solid residues from leaching, etc. The introduction of stricter environmental regulations are forcing the Chilean industry to minimise the generation of waste and promote cleaner production. Gas emissions such as SO2 and arsenic from smelters and process wastewater are the major problems at this stage. The environmental impact assessment of gas emissions in all six largest smelters namely Chuquicamata, Caletones, Potrenllos, Ventanas, Paipote and Chagres led to design a "decontamination plan." The implementation of this plan resulted in (i) the installation of sulfuric acid plants for SO2 abatement and (ii) the installation of electrostatic precipitators to remove arsenic oxides condensed from cooling gases. The aim of this paper is (i) to describe the type of waste associated to the various stages of the metallurgical processes and (ii) review the main abatement technologies used in medium and large size companies.

Jan 1, 1999

By P. C. A. Maia, J Alexandre, F. A. J. Saboya, A. R. G. Azevedo, G. C. Xavier

"This work shows the characterization of clay and the granite waste by-product from the sawing process of the granitic blocks, used as raw material for brick ceramic. Besides, shows the degradation of the ceramic material obtained with different by-product contents in the waste after lab test degradation, is investigated. The clay is obtained from mine use areas of ceramic industry in Campos-RI and the waste is originating from of the area of Cachoeiro-ES, an important center of decorative stone in Brazil. The mixes were made by the addition of 0% up to 10% of the waste in the raw material. After drying and firing up to 900°C, obtained prismatic pieces were considered intact. Physico-mechanical properties were obtained from wet and drying tests in laboratory considering 50 and 150 cycles. The results showed that the use of powder byproduct has a considerably influence on the weathering and strength of the material.IntroductionThe ornamental rocks and coating defines the most promising areas of business in the mineral sector [l]. In this context, the Espirito Santo appears as the main Brazilian state in production and export of ornamental rocks, representing 47% of national production [2] which in tum is one of the economic sectors most representative of this State, due of its transport logistics and port vocation that facilitates the export of such products.It is estimated that the state of Espirito Santo there are approximately 1,200 companies dedicated to the activities of ornamental rock by providing 20,000 direct jobs [ 1]. These mobilize support activities, such as companies that provide machinery, equipment and supplies for industries, including service providers for maintenance.However, the production of rocks produces about 15,000 tons of granite waste/month [3] only in the municipality of Cachoeiro ltapemirim-ES. This is justified by the presence of more than 500 extraction industries, cutting and processing of stone, with about 900 looms, waste generators.According to [4], there is great potential for the use of granite waste in red ceramics introduced for the manufacture of bricks, blocks structural ceramics. and other ceramic products, especially when evaluated on exposure to weathering."

Jan 1, 2014

By Bo Zhou

During secondary aluminum recovery, complex aluminum scraps are melted and refined often in a rotary melting furnace and the aluminum metal has to pass through a molten salt layer and melt down in a bottom aluminum bath. Previous experimental study and industrial observations have indicated that salt shell formation and re-melting on the metal solids in the early stage plays a critical role in the overall melting process of the scrap. In the present paper, mathematical models are developed to simulate the process of salt shell formation and its re melting, as well as aluminum melting in the molten melt. Influence of the salt layer properties, the residence time of the metal particles in the salt layer, the particle size, the temperature of bulk melt were investigated. Reasonable agreement with the measurement data was reached. The developed melting model will be used to construct a population balance model of the scrap melting behavior for a rotary melting furnace, taking into account the distributed characteristics of the scrap. Finally, an overall process model based on Computational Fluid Dynamics (CFD) for the rotary furnace will be constructed, coupling with the population balance model for the scrap melting.

Jan 1, 2003

By V. Ramachandran

Under the Resource Conservation and Recovery ACT (RCRA), generators of listed or characteristic hazardous wastes must find satisfactory means for disposal. of wastes. Initially, for many this meant landfills and deep-well injection. Until recently, mining and metallurgical by-products have largely been exempt from RCRA, but now are coming under its jurisdiction. With the increasing closures of landfills, companies in the U.S. such as electroplaters, miners, metallurgical plants and others are turning to recycling as an alternative to treat their wastes. While the cost of recycling has been challenging, the long-term economics prove attractive because recycling interrupts the cradle- to-grave responsibility for the waste generator. The present paper describes the recycling of hazardous wastes at ENCYCLE/TEXAS. Encycle extracts marketable metals from metal-bearing sludges and wastewater using hydrometallurgical processes borrowed from the mining and metallurgical industry.

Jan 1, 1994

By Y. Fautrelle, F. Felten, O. Metais, Y. Du Terrail

"We deal with the prediction of electromagnetically-driven turbulent flows by means of a Large-Eddy- Simulation method (LES). The model is applied in the case of a liquid metal pool submitted to a polyphase linear electromagnetic stirrer. We investigate two cases: (i) the frequency of the magnetic field is equal to 50 Hz; in that case the effects of the pulsating part of the Lorentz forces may be neglected; (ii) the frequency of the magnetic field is low (f= 1 Hz), then the oscillating part of the electromagnetic forces is taken into account. The LES predictions agree well with the mean velocity measurements, as does the standard k-a model. However, as for the turbulent kinetic energy predictions, there is a large discrepancy between the two models. When the oscillating part of the Lorentz forces is taken into account, the computations show that the fluid flow is sensitive to the unsteady part of the forces. We find that the mean velocity is not affected by the fluctuating component of the force. As for the turbulence parameters, the presence of the pulsating part leads to a significant reduction of the turbulent kinetic energy, whilst the turbulence length scale decreases.IntroductionElectromagnetic stirring is commonly used in various metallurgical processes. In continuous casting for example, it may improve the structure of the solidified metal products. Fluid flows generated by electromagnetic stirrers have been extensively investigated (1 ). As for numerical predictions, many works have been published on the subject. In most of the previous works, onepoint closure models have been used. The most used model is the well-known k-i:: model. Those models yield fairly good results as for the mean velocity prediction. However, it has two main drawbacks:(i) the turbulence is not predicted accurately,(ii) it is not well fitted for unstationary flows as well as transitional turbulent motions, where theReynolds number is moderate."

Jan 1, 1999