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By Rui-Qing Li, John G. Peacey, Peter J. Hancock

"Noranda has been investigating a pyrometallurgical process for the direct recovery of zinc from zinc concentrate and zinc and iron containing residues. The process consists of injecting dry zinc concentrate and secondary zinc materials into a molten iron oxysulphide bath, volatilizing metallic zinc into furnace off gas essentially free of sulphur or S02, fixing sulphur contained in the feed materials as iron oxysulphide matte which is disposed, and recovering metallic zinc in an ISP type lead splash condenser. Combustion of petroleum coke with air or oxygen enriched air inside the oxygen containing matte supplies part of the heat, and the products of combustion dilute the zinc-laden gas to a desired level.This paper describes the process concept, thermodynamic background, experimental tests, mass and heat balance calculation for a conceptual flowsheet, environmental stability of the residue and advantages and disadvantages of the process. Experimental tests have successfully proved the process concept and thermodynamic predictions. Direct smelting of zinc concentrate and residues inside an iron oxysulfide bath has a great potential to become a cost effective and flexible zinc smelting process.1. INTRODUCTIONZinc is mainly produced by a roast-leach-electrowinning process route, which accounts for about 80% of the world primary zinc production. This process produces high quality zinc with very high zinc recovery (>95%) but suffers from several major drawbacks such as using high cost electricity as reductant, producing environmentally problematic iron containing leach residue (jarosite or goethite) and the difficulty in treating secondary zinc feed materials containing high impurity levels, such as electric arc furnace dusts from the steel industry, and other complex sources. Also in some areas, markets for sulphuric acid are distant resulting in negative realizations on acid sales.The Imperial Smelting Furnace (ISF) process is the major pyrometallurgical process to treat zinc-lead concentrate. The advantage of this process over the electrolytic zinc process is its flexibility in treating high-lead, bulk concentrates with high recoveries of lead, copper and precious metals. However, this is a two-stage process involving sintering of Zn-Pb concentrates followed by blast furnace reduction. The process requires large amounts of high-quality coke which is a major operation cost, and the sintering process which results in serious environmental problems."

Jan 1, 1996

By Ph. Cauwe

This paper presents the experience that NESA and MECHIM have gained about recovery of non ferrous and precious metals from complex sulfide materials. Processed materials are from natural deposits or metallurgical by-products or residues. Roasting of these materials is closely related to the pyro or hydrometallurgical processes used downstream of the roasting. Conditions of a first step of roasting the SELECTIVE ROASTING, are analyzed and explained. The roasted products so obtained are characterised by an extended elimination of volatile sulfides (AS, Bi, Sb, Sn, Pb, Hg, ?? ) and are readily available for the pyrometallurgical recovery of non ferrous and precious metals. After the SELECTIVE ROASTING, thanks to. the high porosity obtained in the "selective calcine", the SULFATE ROASTING is per-formed in excellent conditions. Hydrometallurgical tests performed for the final calcine show a high recovery of non ferrous and precious? metals and require only simple and well known processes. Many experimental and commercial data are given.

Jan 1, 1983

By Oscar Restrepo, Juan C. Nino, Henry A. Colorado

New and extraordinary physical-chemical properties of materials at nanoscale open up new applications for the building and infrastructure industry such as structural reinforcements, electronic properties and energy harvesting. Therefore the issues and risks associated with the manufacturing of nanomaterials are now of big concern due to the large volumes and typical processing involved in this industry. This paper presents a discussion and selected applications of nanotechnology in the construction and building materials: from metals and alloys, clay and minerals, ceramics, cement and concrete, asphalt, wood and composites, to finishing systems and some of the most used characterization techniques. Besides the progress in some areas, nanotechnology is just emerging in this field, with many challenges and opportunities, problems unsolved and business opportunities. A discussion regarding the potential health issues and risks of using nanomaterials for workers and the potential environment effects is included as well. New images and diagrams are presented and discussed.

Mar 1, 2018

By Mehdi Asgharifar, Rouzbeh Sarrafi, Radovan Kovacevic

"The surface treatment of aluminum alloys using atmospheric-pressure of low intensity DC plasma arc discharge is investigated in terms of surface properties. With respect to the conventional surface treatment processes for aluminum alloys mostly based on chemical etching or sand blasting, this process is very environmentally friendly and cost-effective. The effect of two processing parameters, the current and the plasma torch scanning speed, on the surface morphology is studied by using a scanning electron microscope. The effects of cathode spots within the tested range of process parameters are determined, and the limiting factors of the process (such as surface cracking) are discussed. The topographical studies of the treated surfaces have suggested potential enhancement of surface properties for different applications, such as preparing surface for painting and adhesive bonding.IntroductionIn the last decade the aluminum alloys are finding broad applications in automotive industry. In order to successfully execute the joining process of aluminum alloys such as arc welding, laser welding, and adhesive bonding, there is a need to remove oxides for welding and texture the surface for bonding along the join line. A number of surface treatment techniques such as chemical etching, sand blasting, and plasma treatment have been used by industry. It is shown [1] that plasma surface treatment is characterized as environmentally friendly, lower cost, and easier to control process. Bogaerts et al. [1] mention that when an adequately high potential difference is applied between cathode and anode, electrons are accelerated toward anode by an electric field coming in collision with gas atoms. The gas breaks down into positive ions and electrons, giving rise to gas discharge. The DC electrical discharges used in industrial plasma sources can be related to their location on the voltage-current curve as shown in Figure 1.It is generally believed that dark discharges other than coronas, and arc or torch plasmas are not very good candidates for surface treatment because oflow or high power density and active species flux. However, the glow discharge plasma is used for plasma surface treatment applications because of its proper power density and active-species flux [2]. Our objective is to investigate the feasibility of using low intensity DC plasma arc discharge as a surface treatment method without damaging the cathodic non-thermionic workpiece."

Jan 1, 2011

By G. T. Lapidus

One of Society’s major concerns with hydrometallurgical processing is the large amount of water that is quintessential to its nature. This is especially troubling in arid areas, where the population struggles to procure potable water for their daily needs. For that reason, it has become our responsibility to conceive, design and implement processing schemes that not only use as little water as possible, but recycle streams within the plant itself and minimize waste that exits its perimeter. With this in mind, the conference will center on the importance of selecting the appropriate chemical systems and integrating material balances to avoid reagent overkill and to detect impurity accumulation. The three “R’s” (reuse, recycle and recovery) of aqueous solutions within the processes are emphasized. Examples of processes for the recovery of lead, copper, precious and PG metals from minerals and waste materials will be presented.

By Banqiu Wu

Zirconium carbide powder has been synthesized from zircon concentrate and methane using a high temperature plasma reactor, a non-transferred DC plasma torch was used as heat source. A high temperature filter consisting of graphite felt was designed, built and operated to separate the zirconium carbide from silicon carbide during the process. Characterization of the collected powders was done by wet chemical analysis using Atomic Absorption (AA), Scanning and Transmission Electron Microscopy (SEM and TEM) and by X-Ray Diffraction (XRD). It was found that the zirconium carbide purity was around 95% with silicon carbide being the primary impurity. The powders had particle sizes between 30 and 80 nm. The effect of several experimental variables are presented as well as temperature and velocity profiles calculated in the reactor.

Jan 1, 1997

By Ping Long, Bin Yang, Jian Wu, Xiumin Chen, Wenli Zhang

In this study, the analysis method of trace element in pure indium using glow discharge mass spectrometry (GD-MS) has been established by correcting the analysis result, which was obtained from non-standard quantitative method of GD-MS. The effect of instrument operating parameters, the resolution and isotopes and the pre-sputtering time on the determination results were investigated respectively. The optimized operating parameters of the instrument were obtained as follows: the discharge current was 37.5mA and discharge airflow was 475ml/min. Mass spectral interferences have been eliminated using selected resolution and isotope. The pre-sputtering time was 30 min. 4 trace elements in two pure samples were determined for 6 times. The RSD were less than 20%. The content of trace elements in indium samples was determined by GD-MS and Chemical Analysis Method of Indium which is tested by inductively coupled plasma atomic emission spectrometry, respectively. The results were consistent with each other.

Jan 1, 2016

By Christian Wögerer

For material or process development as well as for quality checking of materials, thermal diffusivity measurement may be the tool of choice in many applications. Especially if diffusivity is measured locally resolved, a lot of information can be read out of such a ?diffusivity image?. This paper explains the method to measure coplanar specimen like plates and lists some interpretations of diffusivity images, like inhomogeneity of sintered materials, structural voids or inclusions. Diffusivity is a material property, describing transportation of heat in solids in spatial and temporal terms. With thermo cameras it is possible, to measure diffusivity of larger areas simultaneously. The result is an area of diffusivity values that may be plotted or displayed like an image. Locations with lower diffusivity values could be caused by the presents of structural differences in the material, by decomposition of the material components or by inclusions of other material like air.

Jan 1, 2009

By Z. Q. Chen, M. H. Loretto, Y. G. Li

"As-cast, As-forged, as-solution-treated, and solution treated and aged microstructures of Ti-15Mo (IMI205) with and without carbon were examined using optical microscopy, scanning electron microscopy .and transmission electron microscopy. Tensile testing was carried out at room temperature. It was found that carbon acts primarily as a titanium carbide former: Titanium carbides increase slightly the tensile strength, but decrease the ductility of IMI205. These observations are interpreted in terms of the titanium carbide morphology observed using SEM and TEM and the phase diagrams of Ti-Mo, Ti-C, and Mo-C.IntroductionIn a recent study on the development of a burn-resistant 13-Ti alloy, carbon was introduced· into the Ti-V-Cr system in order to optimise the mechanical properties. Research results[1, 2] demonstrate that carbon addition can refine the 13 grain size and improve the stability of the 13 phase in Ti-V-Cr alloys. The most attractive result is that carbon addition produced a marked improvement in the ductility of alloys when the carbon content is over 0.1 wt.% in this alloy system. Even after long exposure, the alloy with carbon addition maintains good ductility. One of the main reasons for the ductilising of the alloy is that titanium carbides can getter the oxygen from the 13 matrix.In view of the success of carbon addition in improving the properties and the stability of the Ti-V-Cr alloy, it is of interest to investigate the behaviour of carbon addition in other beta Ti-base alloys. The objective of the present work was, therefore, to assess the microstructures and mechanical properties of IMI 205, a metastable beta titanium alloy, with and without carbon addition using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), wavelength dispersive X-ray (WDX) analysis, room temperature tensile testing."

Jan 1, 2000

By C. B. Catanach

The development and in place leaching of a chalcocite ore body at Mountain City, Nevada is described. Block caving was used to induce permeability while ore removed during development was leached in heaps on the surface. Copper was recovered by precipitation on iron. Excess ground water which seeped into the mine was pumped into a deep disposal well. A parallel system was used to purify water by lime neutralization. Copper extraction was at an annualized rate of 11% during the first six full months of underground leaching and totalled approximately 30% during six months of heap leaching. Leach solution flow and distribution had a major effect on extraction rate. Enrichment of leach solutions with ferric sulfate did not produce conclusive results until analyzed with the aid of a leaching model.

Jan 1, 1976

By K. Santowski, S. B. Breyner, T. Prietl

"The material properties of alumina products can be significantly improved by adding Cr203 containing raw materials. Cr203 and Alz03 form an alumina-chromia solid solution during firing, reducing the solution potential when in contact with acidic slags. During service, both a high chemical and high thermomechanical load are present for example in the tuyere zones and taphole areas of metallurgical vessels. For such applications conventional alumina-chromia products suffer from discontinuous spalling as a result of high and frequent thermal shock. Therefore, alumina-chromia materials were developed that exhibit improved thermal shock resistance, compared to the standard products, combined with sufficient corrosion resistance. Laboratory tests evaluated the physical properties of the newly developed alumina-chromia grades and a field test in a Peirce-Smith copper converter demonstrated that the material properties meet the corrosion and thermal shock resistance required for this application. IntroductionTo develop refractory products tailored to specific service conditions it is important to have a profound knowledge of the metallurgical processes and furnace conditions [l]. This enables the specific refractory consumption to be minimized and increases the overall operational efficiency. Economic considerations such as steadily increasing energy and resource costs have resulted in companies investing in recycling processes. In the base metal industry for example, recycling operations involve modifications to the smelter feed, process conditions and chemical composition of the process slags. This adversely affects the performance of standard linings and drives refractory producers to search for material innovations."

Jan 1, 2013

By I. K. Chopde, M. M. Dhobe, C. L. Gogte

"The quality of machined surface is becoming more and more important to satisfy the increasing demand of component performance and its reliability. While machining any component, it is necessary to satisfy the surface integrity requirements. Heat treatment plays an important role in improving the characteristics of the material.This work investigates the effect of heat treatment on the surface characteristics of AISI D2 tool steel after Wire-Electro Discharge Machining (W-EDM). The test specimens were prepared by hardening and tempering and then machined with Wire-Electro Discharge Machining process. Optical and scanning electron microscopy, surface roughness and micro hardness tests were conducted to study the surface characteristics of the machined surface. After characterization based on microstructures and test results, it is observed that the recast layer droplets are of smaller size with reduced white layer thickness resulting in higher hardness and lower surface roughness.IntroductionWith the development of mechanical industry, the requirement of alloy materials having high hardness, toughness and impact resistance is increasing. At the same time the quality of machined surface is becoming more and more important to satisfy the increasing demands of component performance and reliability. When machining any component, it is necessary to satisfy the surface integrity requirements. Surface integrity has two important parts. The first is surface texture, which governs mainly surface roughness. The second is surface metallurgy, which concerns to the nature of surface layer produced in machining [2]."

Jan 1, 2012

By San-chuan Tang, Wen Chen, Shun-ming Ning, Kan-ping Yu, Qiang Zhao, Xue-yong Xing

"A new type of desilication agent (PA-2) was selected by experiment based on the analysis of the characters of silica gel, and the influence of desilication type, desilication dosage, pH value, temperature and aging time on the desilicating effect was studied. The test results showed that on the conditions that pH was 2.0, temperature was 20""C, aging time was12 hours and the dosage of desilication agent was 0.23%, the desilication rate was higher than 93% in solution.IntroductionVanadium is an important strategic resources, which applies to steel industry and petrochemical industry. The main materials for vanadium product are steelmaking vanadium slag, stone coal and containing vanadium waste catalyst, etc. And stone coal is a low-grade carbonaceous silicified vanadium resource, which is unique material for vanadium extraction in China. Meanwhile, our stone coal reserves is No.l throughout the world.The silica acid solution containing vanadium is produced by acid leaching of raw stone coal or its roasted ore. The silica content of this solution is mostly high, besides, when pH is higher than 2 , the solution is unstable. Furthermore, it is very easy to generate gel substance with the increasing of pH value and standing time. 'Ibis silica gel is composed of colloidal particles with the size in 0.001 - 0.1 um. As a result, it is very hard even impossible for the following operation of solution."

Jan 1, 2013

By K. Rajani Kanth

Environmental problem is the major concern for any industry and there is a great need to that along green lines. Sangam Dairy being one of the most famous and wide spread Dairies in India, produces wide spectrum of milk products. The BOD levels of effluent water of this industry with MIF treatment were found to be around 100 ppm. Lot of research has been expended in the past to bring down the BOD levels to bare minimum. The main objective of the present study is to minimize the BOD level to the required level stipulated by environmental standards by employing various seeding materials. For this purpose microbes like Bacillus Subtiles, Pseudomonas, Aspergillas, Staphylococcus, and Pencilium have been employed and BOD levels were analyzed. Various Reagents, solutions with different dilution levels have been successfully prepared. Initial and final Dissolved Oxygen levels were determined before and after incubation. From the DO data, BOD was evaluated for all samples and comparison analysis of various seeding material was carried to suggest the efficient seeding material for the ETP plant. In the process, solutions of different dilutions have been prepared using difficult reagents. These samples are treated with above mentioned microbes and BOD levels are estimated. It has been observed that staphylococcus and Pseudomonas proved to be the best seeding materials. When there microbes have employed BOD levels fall to less than 10 and 20 ppm respectively

Jan 1, 2006

By Mike Santaluce

Smelting furnace rebuild projects often require a significant capital expenditure and an extended smelter outage. Smelter operators are increasingly searching for methods and initiatives to shorten furnace rebuild schedules, maintain manageable cost levels, enhance furnace performance and achieve excellent safety results. This paper describes the ?MEPC? Model for furnace rebuilds; a project driven approach which Auburn has developed in response to the need for improving furnace rebuild project outcomes. The ?MEPC? (Management, Engineering, Procurement and Construction) approach better addresses the unique challenges presented by furnace rebuild projects when compared to the traditional EPCM (Engineering, Procurement, Construction Management) model widely in use for these projects today. One key feature of the MEPC model is that a dedicated project management team with representation from all of the major project stakeholder groups is put in place at the onset of the project. The project management team has ownership and accountability for meeting overall project goals over the entire lifecycle of the furnace rebuild project. A second key aspect of the model is emphasis on project management as a completely separate project function with its own specific skill sets, techniques, tools and best practices. These features of the MEPC model offer several advantages in terms of improved planning, coordination, communication and alignment with project goals which contribute to the overall success of furnace rebuild projects. Similar MEPC concepts have been used to deliver excellent project results in other industries and the MEPC approach has been successfully utilized on furnace rebuild projects.

Jan 1, 2006

By Xian-Dong Zhou, Guo-Sheng Sun, Jianzhong Luo, Hong-An Guan

"Oxygen utilization rate of the pretreatment process which adopts biological contact oxidation method for slightly polluted supply water is relatively low, less than 10%, usually lower than 3%. So the aeration amount is not determined by calculated value of oxygen demand when doing process design, but by the ratio of gas and water. The aeration way of the biological pretreatment process for slightly polluted supply water was introduced in this paper. In the foundation of the principles of mass transfer kinetic theory and experimental data, the change law of DO (dissolved oxygen) and ammonia in the aeration tank was analyzed to explore aeration method which will help to improve the overall effectiveness of handling capacity.IntroductionThere are many kinds of filler used in the biological contact oxidation process, such as flexible solid filler, composite filamentous filler, powdery clay filler, particle ceramic filler and so on. Regardless of the different forms of filler, there are a couple of common points in the function of the aeration[1,2]: (1) The aeration process in biochemical tank not only provides adequate oxygen for the biological reaction, but also plays as a role of stirring water; (2) Biochemical reactions mainly happen in the upper reaches of tank, but seldom at down-streams.This paper, from the perspective of changing aeration way, discussed the feasibility of improving the effectiveness of biochemical reactions without increasing aeration amount, which would have some leading significances for the operation and management of similar projects."

Jan 1, 2008

By Sergei A. Degterov

A thermodynamic database for the slag, matte and liquid copper phases in the Cu-Ca-Fe-Pb-Zn-Si-O-S system has been developed for the ranges of compositions of importance to the production of copper. When used with the Gibbs energy minimization software and other databases of the F*A*C*T thermodynamic computing system, this database will permit the calculation of matte-slag-copper-gas phase equilibria that take place during copper smelting and converting. The calculations reproduce within experimental error limits all available experimental data on phase diagrams, activities of components, enthalpies of mixing, matte - alloy miscibility gap and tie-lines. The calculated solubilities of Cu in both S-free slag and slag equilibrated with matte are also in good agreement with experiment under all studied conditions, such as at SiO2 saturation, in equilibrium with Fe, Cu or Cu-Au alloys, at fixed oxygen or SO2 partial pressures and at different contents of Pb, Zn and CaO in the slag. Sulfide contents (sulfide capacities) of the slags are predicted within experimental error limits. The distribution of Pb and Zn among matte, slag, copper and gas has been calculated. The calculations are in good agreement with experimental data and predict the distributions under conditions which are difficult to study experimentally, such as at magnetite saturation or under various oxygen partial pressures and iron to silica ratios in the slag.

Jan 1, 1999

By Ju Shao-hua

Although nowadays gold extraction methods are very abundant, none of them is satisfying, especially, in the field of heap leaching of low grade gold ore. The traditional heap leaching method of cyanide method plays an inglorious role of badly environmental pollution. In this paper, a bran-new and innoxious method of gold extraction system, metal-ammonium-chloride-ammonia (MACA), was proposed, and also analyzed both thermodynamically and practically. Thermodynamically, according to the principles of simultaneous chemical equilibrium and electronic charge neutrality, the thermodynamics of Au-NH4Cl-NH3-H2O system was studied by using the exponential computation method and through MATLAB programming, and the solid figure of its potential - c(NH4Cl) - c(NH4OH) was drawn. The results showed when the concentrate of ammonia is higher than 0.6 mol?L-1, fAu+/Au is only about -0.2 v. Practically, the leaching results of a cuprous gold ore showed that the extraction of gold can reach to 80% in this system. The preliminary results of reduction of the rich solution with copper and zinc powders showed that with deoxygenizing, the reduction effects were relatively good. These new findings and results have established a theoretical and practical base for developing a new process for heap leaching of low grade gold ores in this system. And the new process owns a series of merits such as, non-cyanogens, nontoxic, broader applicability.

Jan 1, 2006

By Henrique Ventura Oliveira

Continuous casting is the most important process for solidification of steels. In this process, the fluid flow pattern in the tundish and in the mould have significant effect on the product quality. Problems associated to fluid flow in the tundish include surface turbulence, ?short-circuits?, formation of dead zones and vortexing. During grade changes, mixing in the tundish plays a significant role in determining the length of the intermixed slab. All these flow aspects can be studied by means of mathematical and physical models. In the last years, numerical simulation of fluid flow has become a very popular tool in the analysis of the performance of continuous casting tundishes. In setting-up these numerical simulations, special care should be taken in choosing the appropriate mesh distribution, the interpolation scheme, the adequate location of the inlet boundary and the turbulence model. In the present paper, turbulent fluid flow in different configurations of tundishes was simulated. Different turbulence models were used in the simulations. Residence time distribution (RTD) and mixing curves during grade changes were predicted and compared to results obtained in physical models. The performances of the different turbulence models were evaluated. For the tundishes that have been studied, the performances of the different turbulence models tested in the present work were similar. There is no evidence that any of the models provided sustained improvement when compared to the well-established standard k- model. All turbulence models tested presented limitations in simulating flows under low turbulent Reynolds numbers.

Jan 1, 2006

By Alex Moyano

The Peirce-Smith converters are traditionally carrying out the converting process of a copper matte in the smelters of Codelco-Chile. However, its production increment is very limited due to the investment magnitude associated to the fulfillment of the environmental regulation. The objective of this paper is to present the Codelco continuous converting process technological advance when converting mattes and/or white metal into blister copper in a Teniente converter unit as an alternative to increment the corporative anode copper production. In 1994, Codelco-Chile started evaluating its ?home made technology? as an alternative to the traditional batch-type converting process. By the year 2001, the Caletones smelter converted liquid white metal to blister copper in a rearranged PS converter continuously. Then, during the 2001-2003 period, several pilot and industrial scale tests were done in a Teniente converter unit at Codelco Norte smelter, evaluating the continuous converting process, i.e., processing liquid mattes (62-68% Cu) to blister copper, demonstrating its technical feasibility with: (i) both constant production of gas flow and SO2 concentration, (ii) production of liquid slag, and (iii) production of a clean blister copper, suitable for the refining process. The promising results have led Codelco-Chile to plan for the 2006 period, a next advanced stage for the continuous converting process evaluation by carrying out a new campaign of tests in a Teniente converter unit at the Codelco Norte smelter.

Jan 1, 2006