Search Documents

By Jarrod Bonsmann

"This paper presents the results of small scale testing to examine the effect of various importantparameters on the response of a vehicle due to the detonation of an explosive charge buried inthe soil below the vehicle. In particular, we were interested in examining what effect change instandoff distance, change in mass, and change in surface area would have on the loading applied.We examined the impulse delivered to the target in all cases and for the change in mass andchange in stand-off distance we examined impulse, kinetic energy, and acceleration."

Jan 1, 2012

By Zhang Hanbo, Niu Liping, Zhang Zhiqi, He Jicheng, Dou Zhihe

"Rutile, ilmenite and Al-Ca complex reducer were used to prepare high titanium ferrous alloy by enhanced reduction-SHS method. The effects of the complex reducer compositions and slag types on the enhanced reduction-SHS process were investigated. The high titanium ferrous alloys were characterized by XRD and SEM. The results indicate that the high titanium ferrous alloys consist mainly of TiFe2, AlTi3 and Al2O3. The oxide inclusions exist resulting in directly the high oxygen content and micro-structural defects in the alloys. The titanium and oxygen contents decrease, but the aluminum content in the alloy increases while the mass ratio of calcium in the Al-Ca complex reducers increases. When the mass ratio of Al/Ca in the Al-Ca complex reducer is 6:1, titanium, oxygen and aluminum contents are 63.75%, 3.01% and 10.72% respectively. When the mass ratio of Al/Ca is 5:1 titanium content is 55.00% nearly and aluminum content is higher than 14.00%, but oxygen content is lower than 2.0%.1. IntroductionThe high titanium ferroalloys with 65%~75% titanium have the advantages of low melting point and high titanium content. They are widely used in special steel refining, while they are also a kind of very important quality orientation alloys in the rage of aviation and aerospace. At present, the methods of preparing high titanium ferroalloy include vacuum remelting and thermit reduction. The alloys prepared by the vacuum remelting method have good qualities and low oxygen content, so it is widely used in Russia, Western Europe and other developed countries. In China, there are abundant rutile resources, but waste titanium is lack, therefore, the preparation method is the thermit reduction. But there are many quality defects in the high ferrotitanium alloy, including high oxygen content, unstable quality and so on. In order to improve the qualities of the high titanium ferroalloy, especially to reduce oxygen content, the domestic and overseas have done a lot of further researches. For example, Sichuan E-mei ferroalloy plant and Beijing Nonferrous Metal Research Institute have prepared high titanium ferrous with 73.77% titanium with natural rutile, but the oxygen content is high. Through controlling the quality of raw material, they obtained the better qualities, but the oxygen content is still very high. South Africa Mintek company have prepared high titanium ferrous alloy with low nitrate by plasma heating under the isolation air conditions, but they couldn’t also remove effectively oxygen in the alloy. The oxygen exists in the form of Al2O3 and titanium protoxide. So it can be speculated that except TiO2 not being fully reduced, the no-sufficient alloy-slag separation is the direct reason resulting in high oxygen and poor microstructure. In view of present technical difficulties during preparing high titanium ferroalloy by thermit reduction, this paper proposed a new method of preparing high titanium ferrous with low oxygen by enhanced reduction-SHS with Al-Ca complex reducer. Ca in Al-Ca complex reducer has stronger reductive ability, it can effectively strengthen the reductive degree of TiO2. The slagging agent CaO CaF2 and MgO can effectively reduce the viscosity of Al2O3 slag to improve its liquidities to strengthen alloy-slag separation effects so that to remove inclusions and oxygen. In this paper, effects of slagging agent type on the reduction and the qualities of high-titanium ferroalloy were studied."

Jan 1, 2012

By Matthias Schnitzler, Herbert Pfeifer, Ralf Bolling

"To transform metals high temperatures are usually needed. A fast and efficient heating can reduce the C02 emitted. The fastest way to heat metals is called direct flame impingement (DFI). The flame impinges upon the item being heated. For this method it is important to know the shape and length of the flame. Laser-induced fluorescence (LIF) technology allows measurements of a two-dimensional field without influencing the reaction or the flow. Commonly used is the measurement of OH-radicals, an indicator of the reaction zone.In the presented study measurements of a turbulent diffusion flame are shown. The position of the reaction zone and the influence of the distance between the item being heated and the burner are investigated. Conventional measurements and LIP-measurements are compared and the potential of DFI to increase the efficiency of heating metals is discussed.IntroductionDuring industrial heating processes a fast and efficient heating technology is required. Two important aspects are the NOx emission and the energy efficiency. The direct flame impingement (DFI) technology has the highest heat transfer rate possible with a gas/air flame. The turbulent high velocity flame jet impinges upon the item being is heated [ 1]. Due to the high heat transfer rate furnace and exhaust gas temperatures are lower. Therefore the energy efficiency is increased and the amount of NOx emitted is reduced.Hydroxyl- (OH-) radicals are an intermediate product that is generated during the combustion of hydrocarbons [2]. They are commonly considered as an indicator for the reaction zone and position of heat release. Figure 1 shows the hydroxyl-mole fraction in dependence of the distance along the gas flow. The figure clearly shows how fast the OH-concentration increases in the reaction zone. Figure 1 also shows that OH-radicals are present in the post combustion region, however in smaller concentration [3].The laser-induced fluorescence technology serves to measure the spatial distribution of OH-radicals in a two dimensional cross-section area of the flame. Therefore the flame dimensions and location can be determined with high spatial resolution without influencing the flow or the reaction [ 4,5]."

Jan 1, 2012

By Steve Johnston, Mowafak Al-Jassim, Fei Yan, Omar Sidelkheir, Alain Blosse, Katherine Zaunbrecher

"Imaging techniques are applied to multi-crystalline silicon wafers and solar cells throughout the production process. Photoluminescence imaging, both band-to-band and defect-band, is used to characterize defects and wafer quality at all process steps. These steps include bricks sawn from ingots, wafer sawing, cleaning and texturing, emitter diffusion, edge isolation and glass removal, anti-reflective coating/passivation, and metallization of finished cells. Bricks, wafers, and cells can be imaged at a rate commensurate with in-line measurement, giving spatial information to characterize quality and defect content. Photoluminescence images on silicon bricks can be correlated to lifetime measured by photoconductive decay and could be used for high-resolution characterization of material before wafers are cut. The defect areas in as-cut wafers are compared to imaging results from electroluminescence and lock-in thermography, and cell parameters of near-neighbor finished cells, showing correlations to efficiency, open-circuit voltage, and short-circuit current.IntroductionImaging techniques can rapidly characterize material quality and defect density. Photoluminescence (PL) imaging can be applied to silicon from the brick level to all wafer process steps [1-8]. At the brick level, material thickness allows for measurement and correlation to lifetime where surface recombination effects are minimized [6, 7]. At the as-cut wafer level where thin unpassivated wafers prevent accurate lifetime assessment due to surfaces, defects can still be categorized and quantified to predict finished cell performance [3-5]. Defect regions can be identified by recombination-limited band-to-band PL or by defect-band emission [9-12]."

Jan 1, 2012

By O. F. Ochonogor

Laser metal deposition (LMD) is an additive manufacturing technique whereby a stream of metal powder is consolidated by a focused laser beam on the surface of a substrate or engineering component. The interaction zone between the laser beam and powder particles is scanned superficially, generating tracks of deposited material. The tracks are overlapped in a deposition strategy in accordance with slices of a CAD model. Successive layers of material are built up to fabricate a near net shape part. In this work, the technique is used to fabricate metal matrix composites (MMCs) by using an elementally blended feedstock combining metal and ceramic powders in the melt pool, which melt and solidify to create the required morphology. Ti6Al4V + TiC MMCs were produced with 10, 20, and 30 vol.% reinforcing ceramic, and Zr + TiC MMCs were fabricated with 10, 20, and 30 vol.% TiC. The deposited thin walls were analysed using optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and indentation testing. In both systems, the analysis revealed the presence of partially melted TiC particles embedded in the metal matrix along with fine dendrites of re-solidified ceramic. The dendritic structures in the Ti-based composites were confirmed as TiC, whereas in the Zr-based composite the Zr metal reacts with theTiC to form ZrC, leaving Ti in solid solution. Both the MMCs show an increase in microhardness with increasing ceramic (carbide)content, reaching a peak HV0.1 value of 500 in the Zr- based MMC and HV0.1 of 550 in the Ti based MMC.

Jan 1, 2012

By Scott Scovira

All flyrock incidents have the potential to result in injuries or fatalities that can result in loss of company reputation, license to operate with clients, and bear the exposure to high cost liability. From 2007 to 2009, one NA Quarry and Construction Business experienced a series of flyrock incidents. In the Spring of 2009, this business declared that the frequency and severity of Flyrock Incidents had reached an unacceptable level. A Flyrock Elimination Program was launched.

Jan 1, 2012

By Andre Zingano

The variation in pillar behavior at underground coal mines working in the Bonito coal seam is observed in both research and mining company case studies. There is no consistency in pillar behavior, as it varies from mine to mine. In some cases, it is possible to find rib yields for both excavation modes and pillar sizes. This paper?s objective is to investigate pillar behavior for different load conditions and pillar sizes. Three-dimensional numerical simulation models considering these factors were built. A matrix was then assembled to compare pillar behavior between loading conditions, as well as between different pillar sizes with the same loading condition. The results showed some pillar rib plasticity due to vertical loading and stress relief independent of the pillar size and load. For the same load conditions, the yielding thickness is the same for different pillar sizes.

Jan 1, 2012

By Matthew Tunnicliffe, Akram Alfantazi, Paul Nesbitt, Farzad Mohammadi

"Lead and its alloys are proper candidates for anodes in electrowinning processes mainly because they are insoluble in the leach solutions and relatively cheap. However, the annual cost of corrosion problems associated with these anodes is millions of dollars. In this study lead-silver and lead-calcium anodes were tested under typical nickel electrowinning conditions and the effect of chloride on the corrosion performance of the anode materials was investigated. Corrosion rates of the anodes were calculated using the discharge plateau (reduction of lead dioxide to lead sulfate) after galvanostatic experiments. It was found that lead calcium anodes have the highest corrosion rate both in the presence and absence of chloride. Surface morphology of the electrodes was studied using SEM and the corrosion products were characterized using XRD.IntroductionLead (Pb) is usually the preferred material for commercial anodes since it is insoluble in the leach solution and the costs are manageable. One advantage of using an insoluble material as an anode is the higher purity of the cathodic deposits and better quality of the end product. During nickel electrowinning, metallic nickel is deposited on the cathode while oxygen evolution reaction (OER) takes place on the anode. In practice, relatively high potentials are necessary for the reaction to proceed at the desired rate because of the high overpotential of OER on lead. Lead anodes get oxidized in typical electrowinning conditions and usually have two to three years of lifetime. Although the price of each anode is insignificant, the overall cost of corrosion of these anodes is considerable, which is due to the large number of anodes used in a plant, typically two to three thousand. Therefore, corrosion is a significant problem associated with lead anodes in commercial nickel electrowinning plants and industries show interest in addressing this problem. Corrosion of lead electrodes in acidic environments has been previously the subject of many research studies [I-7]. It has been reported that, during the anodic polarization of lead, several phases may be present on the surface, depending on the potential range that is being studied [8]. Lander showed that lead is oxidized at potentials higher than 0.252 YsHE with tetragonal lead monoxide being the main reaction product [9]. At 0.666 YsHE lead can transform to lead dioxide; however, it is not stable and transforms to lead sulfate and lead oxide. At potentials higher than 1.684 YsHE, lead dioxide is eventually a stable phase and forms a protective layer on the surface [I 0, 11]. Under conditions of a typical nickel electrowinning plant, usually a 200 A/m2 current density is passed through the electrodes."

Jan 1, 2012

By C. Norden

The purpose of this article is to show how a representative overall equipment effectiveness (OEE) measurement can be calculated for an underground coal mining bord and pillar batch process. The calculation method, the typical losses (which include planned and unplanned availability losses, coal quality losses, and process rate losses) and the underlying logic are presented and discussed. It is argued that the current traditional underground bord and pillar mining process can currently provide a maximum theoretical OEE of only 49 per cent, while a realistic benchmark target should be in the order of 37 per cent, which relates to an average of 2400 t per shift or 1.2 Mt/a. In addition, it is argued that the current bord and pillar process is the current bottleneck to further improvement past the 2400 t per shift benchmark, and that fundamental process changes will be required to eliminate this bottleneck.

Jan 1, 2012

By H. Paudyal, K. Ohto, H. Kawakita, S. Alam, B. Pangeni

The orange waste after lime water modification was converted into promising adsorbents for fluoride by metal loading reaction. The effectiveness and mechanism of fluoride adsorption on metal loaded orange waste gel from synthetic and real plating solution were investigated. Amount of zirconium(IV), aluminium(III), cerium(III), lanthanum(III), titanium(IV), vanadium(IV) and tin(IV) loaded on orange waste from aquearegia dissolution were evaluated to be 1.62, 1.16, 0.93, 0.95, 1.20, 1.12, 0.97 mmol/g respectively. The maximum adsorption capacity (qmax) of zirconium(IV), cerium(III), lanthanum(III), iron(III) and aluminium(III) loaded orange waste for fluoride ions were evaluated to be 1.74, 0.91, 1.07, 0.98 and 1.01 mmol/g from aqueous solution. The mechanism of fluoride adsorption by metal loaded orange waste was inferred to be ligand exchange reaction. Application of zirconium(IV) loaded saponified orange juice residue(SOJR) for real plating solution showed effective removal of trace concentration of fluoride down to the accepted standard. The negligible interference of co existing anions like nitrate, carbonate, sulphate and chloride makes zirconium(IV) loaded SOJR a promising sorbent for waste water treatment. The adsorbed fluoride from fluoride loaded zirconium(IV)-SOJR was effectively desorbed by using alkali solution for its regeneration. This work shed light on the potential application of metal loaded SOJR to remediate fluoride contaminated water for environmental relevance.

Jan 1, 2012

By M. Tangstad, H. Mølnäs, J. D. Steenkamp

"Temperature affects several aspects of pyrometallurgical systems, including thermodynamics and reaction kinetics. Reliability of temperature measurements in laboratory and plant applications is thus important from process, safety and financial perspectives. This case study briefly introduces different techniques utilized for temperature validation, and demonstrates temperature validation on laboratory scale utilizing the wire-bridge method. Pt/Ptl3Rh thermocouple hot junctions were constructed by mechanically connecting thermocouple wires through a pure metal bridge consisting of copper, gold, nickel or palladium wire. When heating the wire-bridge thermocouple alongside a regular Pt/Ptl3Rh thermocouple, temperature offsets were quantified as the wirebridge thermocouple short-circuited at the melting points of the pure metals. At the melting points of gold (1064°C) and palladium (1555°C), average measured temperature offsets were -2.1°C ± 2.3°C and 0.2°C ± 0.4°C, respectively. Results from the copper and nickel wire-bridges were inconclusive. The paper concludes with a discussion on the potential industrial applications of the technique.IntroductionThermocouples are probably the simplest of all temperature sensors, but are widely utilized due to simplicity, versatility and ability to handle a variety of experimental conditions and industrial applications. Additionally, thermocouples are often the only option in research laboratories requiring high temperature measurements, and a high level of reliability is usually required from thermodynamic, kinetic as well as safety points of view.The study presented here originated from a test program where the compatibility between different types of carbon-based refractory materials and industrial slag produced in silicomanganese furnaces were investigated on a laboratory scale utilizing the static crucible test[l]. Due to the nature of the silicomanganese production process, the compatibility tests were to be conducted at 1600CC[2]. Details of the experimental set-up utilized for the compatibility tests are discussed in the Experimental Set-up and Method Statement section later in this paper."

Jan 1, 2012

By I. Southern, S. Kelebek

"Smelting furnace bricks contain significant quantity of base metals trapped in refractory material. A series of flotation tests were carried out on samples of old bricks from Sudbury area to examine upgrading behaviour for recycling purposes. Depending on the grind size used nickel recoveries varied from 60 to 90.6% with corresponding grades of 20% and 14.7%Ni. There is a trade-off between nickel and copper. The nickel has responded well to fine grinding, however, the copper recovery suffered from it. Mineralogical characteristics and flotation behaviour of the brick material are discussed in reference to those from the primary ore. INTRODUCTIONMineral processing is well recognized as a mature technology not only for the mining industry, but also for the environmental industry for the purpose of remediation and recycling. Materials available for recycling are usually the products of many years ago. There are multiple stake holders in this area. In general, when the processing results in a product that can be reused or sold, the company carrying out the remediation makes a profit, while the regulators and the public are pleased due to a cleaner environment. From these points of view, there have been many papers published over the years on various mineral processing techniques applied to separation of many different materials including from mining and metallurgical industries (Wilson et al., 1994; Tsunekawa et al., 2005; Saikia et al., 2012).Flotation may be viewed as the backbone of the mining and metallurgical industry since its invention for separation of solids from one another almost a century ago. It is capable of recovering a variety of finely divided different solids following their liberation from each other. Its versatility and highly competitive nature in terms of cost per tonne of material processed, accounts for its occasional uses in the environment engineering area. In the mining industry, flotation is the standard method used for the sulphide ores. It can be applied as a bulk flotation and/or differential flotation. Bulk flotation, which refers to co-flotation of several components from their source, is most suitable for environmental cleanup objectives. Desulphurisation of various plant tailings is a typical example of this (Benzazzoua et al., 2000)."

Jan 1, 2012

By Timothy Fogarty, Gregory Poole, Roger Reeder, David Switz

This project involved the construction of a new pump station and intake structure at an existing water treatment facility. Although the project involved a significant amount of rock removal, the specifications said no blasting.

Jan 1, 2012

The SFR system utilizes a skimmer or extractor placed at or near the slurry-froth interface where there is a higher concentration of valuable mineral particles. With assistance of hydrocyclones, it is possible to classify the extracted particles into coarse and fine particle streams, that can be handled separately. It also allows the coarser solids to be separated from entrained low-value fines. The first test results with the SFR system significantly improved both coarse and fine particle recovery in a flotation cell. The SFR system was tested in the flotation circuit at a copper-moly concentrator, and the results show that the use of the skimmer has huge potential to increase the froth recovery (Rf) of both molybdenum and copper.

Jan 1, 2012

By Francois Barthelat, Sam Goroshin, David Frost, Alexander Cappozi, Atefeh Nabavi

"In this study, a novel chromium–chromium sulfide cermet was produced by self-propagating high-temperature synthesis (SHS). Conventional techniques for manufacturing metal sulfides are complex, environmentally harmful, and not suitable for producing complex-shape articles. To overcome these disadvantages, a new method for the preparation of the metal-sulfur precursor charge is proposed, which can be described as reactive casting. The first cermet samples produced with the SHS process were found to be very porous, brittle, and have low mechanical strength. The possible sources for the generation of porosity were identified and analyzed and the process for manufacturing the cermet was modified. By improving the manufacturing process, the porosity inside the produced cermets was reduced from 70% to 12%.IntroductionMetal sulfide composites are in high demand in the chemical, metallurgical, and electrical industries because of their valuable characteristics such as hardness, semi-conductivity, electroluminescence, infrared transparency and catalytic properties. Current manufacturing methods for metal sulfides usually involve one of two different principal methods, including a complex multistage wet chemical process involving the precipitation of the corresponding salts from an aqueous solution with hydrogen sulfide, or hot sintering of the respective elemental reactant powders in a resistive furnace in a high-pressure inert or hydrogen-sulfide atmosphere [1, 2]. These conventional methods for synthesizing ceramic metal composites are complex, extremely time and energy consuming, environmentally harmful, and rarely able to manufacture articles with complex shapes. Therefore, in order to overcome these disadvantages, self-propagating high-temperature synthesis (SHS) was considered as an alternative method that offers significant improvements over the traditional cermet manufacturing methods [3]. SHS, which is a relatively new and attractive method for producing a wide range of advanced materials, is based on the self-sustaining feature of the highly exothermic reactions of the reactants. The SHS process results in high product purity, since the high temperatures generatedin the reaction cause any impurities to volatilize [4, 5]. SHS has low energy consumption and doesn’t require an external energy source and complex equipment, and it is self-contained [1, 5]. Since combustion synthesis has low power requirements, it is one of the few methods of materials synthesis that is feasible in outer space. Also, the process has a low cost and is capable of directly synthesizing articles with the desired shape, size and structure [5, 6]. The chemical reactions associated with SHS are typically completed in a few seconds leading to the formation of the condensed product. The high reaction rates and relatively rapid cooling in SHS reactions can avoid undesirable grain growth in products which often occurs with the conventional sintering method [3, 5, 7]. The traditional method for sample preparation in the SHS technique is to compact the reactant mixture powders in a steel die by a press to a typical density of about 80% of the theoretical maximum value, before igniting the mixture [8]. This method requires a large compression force to increase the green density and to minimize any pores in the green compact. To overcome these disadvantages, a new method for the preparation of the precursor charge in metal-sulfur by SHS is proposed which can be described as melt casting of a reactive mixture, or reactive casting in short."

Jan 1, 2012

By S. J. S. Ferreira

Anglo American Platinum's Khomanani 2 shaft changed over from down-dip mining to breast mining in 2004. The changeover was made to ensure that production targets were met, as it was said that predevelopment for down-dip mining was not fast enough to sustain the required ore reserves; nevertheless, production performance did not increase as expected. In this study a trade-off was performed between down-dip mining and breast mining on the Merensky Reef at Khomanani 2 in order to find the most suitable method for mining the Merensky Reef. Data was gathered by means of a literature survey, underground observations, and interviews with personnel as well as data from various departments on the mine. The two mining methods were studied and then evaluated in terms of the following criteria: safety, mining rate, cost and other factors which were identified as the main drivers of the mine. A scaling system was used to rate the performance of the two mining methods. Analysis of the results shows that down-dip mining and breast mining have the same safety performance ratings. Breast mining has a better mining rate performance than down-dip mining. Breast mining was found to be costly in comparison with down-dip mining, which has a good cost performance rating. The overall ratings of the two mining methods are very similar, with down-dip mining achieving a rating of 76 and breast mining 75.5 out of an optimum 102. Khomanani 2 currently practices breast mining, and with such a slight difference in performance rating between the two methods, it will not be worth changing over to down-dip mining as production is likely to be adversely affected during the changeover. Down-dip mining does, however, have potential for improvement in its performance rating. Further studies focusing on the improvement of the mining rate performance for down-dip mining are needed to see if this potential can be realized. If significant improvement can be made in the performance rating for down-dip mining, a changeover to down-dip mining can be reconsidered.

Jan 1, 2012

By R. E. Mitchell

The environmental impact assessment (EIA) is the accepted method for evaluating proposed mining and other industrial projects to obtain regulatory approval and to help companies plan for responsible development. Another increasingly common evaluation system for proposed projects is the environmental, social and health impact assessment (ESHIA). An ESHIA differs from an EIA for its generally more comprehensive and inclusive approach to evaluating potential impacts, such as on public health, and other features such as an ecosystem services approach to assessing biophysical and community impacts. An ESHIA may also be required by certain lenders for financing major projects. In this paper, EIA standards for the province of Alberta, Canada are discussed and compared to ESHIA. It concludes with several recommendations for consideration.

Jan 1, 2012

By Signe Kjelstrup, Leiv Kolbeinsen, Marit Takla, Odne Burheim

"This paper presents a Seebeck-type solid state thermoelectric power generator unit, designed to investigate the possible recovery of radiant waste heat at a silicon plant in Norway where roughly 703 of the total input energy leaves the process as waste heat. The unit is 0.5 m x 0.5 m and is built of 36 commercially available thermoelectric devices based on bismuth telluride p - and n - type semiconductors. Thermoelectric devices directly convert fractions of a heat flux into an electric current (and vice versa) and may therefore be convenient for recovery of waste heat when the heat source is discontinuously available. The purpose of the thermoelectric unit is to give a proof of principle of direct thermoelectric energy conversion on a large scale. We present the initial test results for the generator. At an average temperature difference between the heat reservoir and the heat sink of 98°C, we measured an open ciruit potential of 23.44 ± 0.06 V and the matched load power output was 39.4 W. At a temperature difference of 220°C, we predict the generator open circuit potential to be 40.8 V, which corresponds to an efficient Seebeck coefficient of 242 µV /K, and matched load power output to be 120 W.IntroductionThe world's power demand increases, driven by population growth and increase in living standards and simultaneously global warming is recognized as one of our most serious environmental problems. According to the International Energy Agency[l], the industrial sector accounted for approximately one third of the total global power consumption in 2005. Increasing the energy efficiency of industrial processes thus represents a benign and substantial route for addressing environmental concerns and energy security.In accordance with the second law of thermodynamics, all real processes are associated with lost work which is energy being dissipated as heat to the surroundings[2]. Improving the energy efficiency of industrial processes is about finding the process path associated with a minimum of lost work. The more evenly the losses are distributed, the smaller are the losses [3, 4]. In addition, exploiting the unavoidable waste heat will contribute to improve the energy efficiency. The waste heat may be utilized for heating purposes and/or it can be upgraded to work for instance via some sort of heat engine."

Jan 1, 2012

By Guillermo Rios, Arbizum Cristina, Joa Viflals, Alba Sunyer

"Atlantic Copper is one of the largest copper producers in Europe. Its production facilities are located in Huelva (Spain) and account for the smelting of over one million tpy of concentrates to produce up to 260 ktpy cathodes and 900 ktpy of sulphuric acid. During copper concentrate smelting, the slag coming from the flash furnace and PS converters are treated in an electrical slag cleaning furnace. As a result of the treatment of the off gases from this furnace, approximately 2,000 tpy of a Zn-rich filter cake are produced and are sent to authorized waste managers. This paper describes the characterization of this material and the preliminary results of a new process to recover zinc as a pure zinc hydroxycarbonate while lead is collected as an indium-rich anglesite product. The behavior of impurities (Cd, As, Tl, Sn, Sb, Bi, Cu, Se, Te) in the leaching, solution purification and precipitation steps is also reported.IntroductionThe Atlantic Copper Metallurgical Complex in Huelva (Spain) was commissioned in 1970 with a capacity of 40,000 tpy of copper from concentrate. In 1975, the old blast furnaces were replaced by Outokumpu flash smelting furnace (FSF) technology, and the copper refinery capacity was increased to 108,000 tpy. Between 1994 and 1996, an expansion project was carried out to increase the copper from concentrate and cathodes to 250,000 tpy and 215,000 tpy, respectively. This expansion basically consisted of a new sulphuric acid plant, replacement of the anode furnaces by two 400 t units, redesign of the slag cleaning furnace (SCF), an increase in the electrolytic cells to 1,120 and implementation of ISA permanent cathode technology. Furthermore, a debottlenecking project has led to a capacity of 1,000,000 tpy of fresh concentrate since 1997. Meanwhile between 1995 and 1998, a cathode production rate of 260,000 tpy was reached as a result of a progressive increase in the current density in the refinery."

Jan 1, 2012

By M. Gholinejad

Applying non-explosive expansion material (NEEM) is one of the safest methods for rock fracturing, especially in a hard rock quarry. An experimental study was conducted to determine the pressure exerted by NEEM in a hole, which is necessary for analysing rock fracturing, particularly in a numerical modelling. Stress distribution was developed in a thick-wall cylinder in order to measure the tangential strain on the external boundary. In the experiments, nine pipes of different materials and varying diameters were selected and then loaded internally with a general type of NEEM. Through electrical strain gauges, the tangential strains were recorded on the external boundary of the pipes. The results obtained from these tests and existing data from previous researchers were utilized for the statistical analysis. A new experimentally-derived formula is proposed for determining the pressure exerted by NEEM by multiple parameter regression with a high correlation coefficient. The proposed model has a nonlinear form with three independent parameters i.e. the hole diameter, the time, and the modulus of elasticity of the material.

Jan 1, 2012