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By K. Kawagishi, K. Matsumoto, Y Koizumi, H. Harada

A new burner rig for cyclic and hot corrosion testing of Ni-base superalloys and high-temperature coatings has been developed at the National Institute for Materials Science (NIMS) in Japan. The concepts of the rig design include: use of kerosene as fuel, easy operation for materials research and multi-specimen testing capability per test run. The burner rig consists of six blocks including combustion block, corrosion-solution injection block, furnace block, specimen block, controller block and outdoor facility block. During verification testing, it was confirmed that the rig had accurate specimen temperature control within ±1? from 600 to 1100? and automated easy operation. Cyclic testing of several Ni-base superalloys was conducted. The results from 50 cycle testing indicated that a new NIMS alloy developed for 1700? class gas turbine had higher oxidation resistance than CMSX-4. This new burner rig testing capability at NIMS can be very useful for future oxidation, hot corrosion and coating durability studies.

Jan 1, 2010

By B. MohammadSadeghi, S. Bakhshivash, M. Haghshenas, F. Rahimi

"Constrained groove pressing (CGP), as a severe plastic deformation (SPD) technique, is one of the applicable methods for sheet metal forming capable of producing ultra-fine grained materials (UFGMs). In CGP, processing and die design parameters can significantly affect the deformation response of sheet metal specimen. Having said this, in the present research the effects of die design variables and processing parameters (i.e. shear angle and friction) on the deformation behaviour of an Al-Mg-Si Alloy are studied thoroughly. Finite element analysis (FEA), was used to evaluate the effectiveness of mentioned parameters on the deformation homogeneity, strain distribution and pressing load variations. Also, mechanical properties of the deformed sample in term of micro-hardness was analyzed. It is observed that with increasing the shear angle, effective stress, strain and pressing load are enhanced. Moreover, by increasing the coefficient of friction, pressing load enhances. The color coded micro-hardness measurement showed a good agreement with the strain distribution obtained from FEA (higher hardness for the zones associated with higher shear plastic strain values).INTRODUCTIONWork hardening results in enhanced mechanical properties upon cycles of deformation (Hosford & Caddell, 2007). However, the formability of the processed products are affected by work hardening reducing the possibility of processing in subsequent deformation cycles. Therefore, many industrial processes cannot be performed on sheet metals to produce products with desired mechanical and physical properties (Valiev, Islamgaliev, & Alexandrov, 2000). Severe plastic deformation (SPD) is an effective grain refining technique which can impose large plastic strains through cold working on a metallic specimen (Bisadi, Rastgou, Payganeh, Zeynali, & Ghahremani, 2010). SPD techniques are mainly categorized into three types; sheet, bulk and tube forming. Among SPD sheet forming methods, Constrained Groove Pressing (CGP) (Shin, Park, Kim, & Park, 2002), Accumulative Roll Bonding (ARB) (Saito, Tsuji, Utsunomiya, Sakai, & Hong, 1998) and Repetitive Corrugation and Straightening (RCS) (Zhu, Lowe, Jiang, & Huang, 2001) possess potential applications in manufacturing industries."

Jan 1, 2016

By W. B. Agocs

"IntroductionWITH THE DISCOVERY of natural radioactivity at the end of the 19th century, and the design of equipment for the detection of this phenomenon, radioactivity surveys bad their inception. Early in the 20th century it was found that almost all rocks are radioactive to a certain degree. This radioactivity is due to the nuclear disintegration of six naturally radioactive elements: potassium, thorium, uranium, rubidium, samarium, and lutecium.The radioactivity of these elements manifests itself by the emission of some concentration of alpha, beta, and gamma 'rays'. Of these, the alpha and beta 'rays' are, respectively, helium atoms and electrons, while the gamma 'rays' are short wave length x-rays generated in the nuclear disintegration by the transformation of mass into energy.The alpha and beta rays, being particles of matter, are stopped ve• easily by material barriers, but gamma rays are extremely penetrating and they will pass through a foot or more of rock or several inches of lead.The radioactivity may be detected by the causing of ionization by the radiation. The radiation detectors may be divided into four classes: ionization chambers, proportion al counters, and Geiger counters, all of which use gas for ionization, and scintillation counters, in which a solid is ionized. The basic principle of all these detectors is the same; the difference lies in the method used to measure the degree of ionization produced by the rays. Currently, the scintillation counter is displacing, the other instruments in radioactivity surveying."

Jan 1, 1955

By M. Oliazadeh, A. Vazirizadeh

"The inclusion of small amounts of silicon, phosphorus and sulphur in iron ores or concentrates can have a profound effect on the steel making process and thus on the final iron and steel products. In nature however, it is inevitable that iron deposits contain unwanted elements. Each element has its own distinct effect on the final steel product. The effect of high silicon is the formation of gray iron. Phosphorus mainly increases hardness and strength, lowers solidus temperature and increases fluidity and cold shortness. Finally sulphur contamination causes cracks in the iron texture when smelting and forms white iron when casting. Overall, the acceptable level of phosphorus, sulphur and silica in the iron concentrate should be less than 0.04%, 0.15 % and 1.5 % respectively.Scarcity of high grade iron ores necessitates using lower grade ores with higher amounts of impurities. The purpose of iron concentrators is to increase iron grades to an appropriate level suitable for steel making as well as removing impurities. Although many impurities can be traced in the ore, the most predominant impurities are limited to one or two elements. In this paper the beneficiation methods for removing SiO2, P and S are presented, including flotation, and the parameters that need to be considered in the design of beneficiation plants are discussed. Finally industrial cases are discussed along with their metallurgical performance.INTRODUCTIONIn metal sector, value of iron ores and concentrates is determined by iron percentage as well ascontent of:• Useful elements (Mn, Ni, Cr, V, Ti): natural alloying elements in steel• Deleterious impurities (S, P, As, Zn, Pb, K, Na): impair metal properties or complicate operational process in blast furnace• Fluxing components (Si, Ca, Mg,, Al)Sulphur and copper result in red-short, phosphorus is the cause of cold brittleness and arsenic and copper decrease welding characteristics. Sulphur should not exceed 0.15 in commercial ore. Acceptable sulphur content in ores and concentrates for producing sinter and pellets is 0.6%max, as sintering and heat hardening of pellets remove sulphur 60-90%. Phosphorous content in ores, sinter and pellets is limited to 0.07%-0.15%. 0.00.1% As max, 0.1-0.2% Zn max and up to 0.2% Cu are allowed in iron-ore part of the blast furnace burden for the production of standard conversion pig iron. Slag-forming components are divided into basic oxides (Ca, Mg) and acidic (Si, Al). Higher ratios of basic to acidic oxides are preferred since this reduces raw fluxing material."

Jan 1, 2016

TIPS FOR SUCCESSFUL WASTE MANAGEMENT ? WASTE MANAGEMENT PLANS ? Define the question to be asked in waste characterization studies ? Calibrate assessments and designs with field conditions ? Ensure consistent with short, medium and long-term mine plans ? Design robust plans - goalposts and expectations will change ? Fully assess and integrate costs into economic models ? Integrate waste specialists into the feasibility and design teams ? Keep it simple and when you can?t, communicate it in simple terms ? PLAN EXECUTION ? Integrate the waste management plan into daily mine operations ? Identify the critical KPI?s , track them and set clear action triggers ? Know the difference between knowledge and data ?make sure you retain knowledge and document the important Maintain management, engineering and operational focus through the mine life

May 1, 2010

By J. A. E. Bell

"Inco has shifted part of its traditional extractive research effort at its J..Roy Gordon Research Laboratory in Mississauga toward new, value-added products. Most of the effort is being expended on new Ni powders for batteries and new Ni-coated products which will be produced in Inco's carbonyl nickel refineries. New products under development are Ni-coated powders, Ni-coated fibres and ultra-fine Ni powders. Other new products for advanced material applications include controlled expansion composites, NiGOLD strip, Thermal barrier coatings on Inco alloys, and plasma coatings.Research and Corporate Strategic ThrustsThe newest strategic thru st of the company is to increase the value of the primary metal products. These new products are to be in addition to any new alloys or downstream alloy fabrication.Historically Inco has had the highest research expenditures in the extractive metallurgy field in North America. This has resulted in many new processes including flash smelting , matte separation, fluid bed roasting, pressure carbonyl refining and cobalt electrowinning which have contributed to establishing Inco as the lowest cost nickel producer. The recession of the 1980s caused a restructuring of Inco research and corporate goals .As shown in Figure I, from 1975-1982, i.e. pre-recession, Inco spent around 33 million dollars per year on research. Some 48070 of that sum was spent in Corporate Laboratories in Sterling Forest in the United States and in the United Kingdom , mostly on alloy associated research. A further 10% was spent on alloy research at the alloy production facilities in Hunting- ton, West Virginia, and Birmingham and Hereford in the United Kingdom. On extractive research, 13% was spent by process technology groups at the plant s, 20% at the pilot plants in Port Colborne and 9% at the J. Roy Gordon Research laboratory.The relative research expenditures (Fig. 2) have decreased so that today they are at the same level as 1975-80. The research as a per cent of sales has been cut from 2.2% to 1.2% of normalized sales. A normalized sale price of $4.00/lb Ni was used in the 1988 figures. This was partly achieved by closing Corporate Laboratories. Most of the essential alloy research was moved to producing plants and total alloy research is now 27%.A new thrust initiated in the 80s was mining research which now accounts for 20% of research expenditures. Over a period of the past five years this research has doubled the mining productivity in Inco. The pilot plant expenditures have been cut in half. One entire research station at Port Colborne was converted into a platinum group metals intermediate refinery. The decrease in pilot plant expenditures has been compensated by full scale plant trials devoted to the S02 abatement program at Sudbury."

Jan 1, 1990

By S. Komar Kawatra, Youlian Zhou, Joseph A. Halt

"Bentonite clay has been the most common binder for iron ore pellets. Although bentonite increases pellet strength and durability, it has several disadvantages. For example, its use increases the cost of pellets and decreases pellet purity due to its composition and the higher levels of flux required to meet basicity limits. Several new types of binders have been proposed to replace clay. The binders include starch, modified humic acid (MHA), and dispersants. These binders were used to pelletize a magnetite concentrate from the United States. Typical doses of each binder type were 0.05-0.1 % starch, 0.5-0.75 % MHA, and 0.05 % dispersant. At these doses, the pellets exceeded the minimum recommended values for wet drop, dry compression strength, and fired compression strength. Pellets made with the MHA and dispersants had the lowest abrasion rates of the new binders, and were comparable to pellets made with bentonite clay. In this paper, we compare the new binders, considering pellet quality and the advantages and disadvantages of each binder type.INTRODUCTIONIron ore pelletizers need binders in order to make good quality iron ore pellets. The typical binder is bentonite clay, an alumino-silicate material. Bentonite increases the ballability and strength of iron ore concentrates, but reduces pellet iron grade and reducibility. As high quality bentonites can be expensive to ship, low quality bentonites are often used at significantly higher doses – this reduces iron grade and reducibility even further. Thus, several new types of binders have been proposed to replace bentonite clay.In this paper, we present several new binders for iron ore pellets: starch and modified humic acid (MHA). These have been tested alone and in mixtures with dispersants, or else with bentonite clay. Starch, MHA and their mixtures are briefly described below."

Jan 1, 2016

By Joseph Daniels

When Dame Nature shook her horn of plenty and distributed her bounties over the face of the earth, she blessed the Pacific coast with many riches, but with these she added many offsetting disadvantages or handicaps, designed, no doubt, to effect a proper balance between wealth and economy. Nowhere is the application of the law of compensation more aptly illustrated than in the matter of fuel and power resources. A glance at the map of the Pacific northwest will show that west of the Coast Range batholith we are bounteously supplied with coal, with timber, with water power, and with tributary resources of oil from California. Alaska, British Columbia, Washington, all contain large resources of coal; Oregon and California to a lesser degree, but, compensating the golden state for its deficiency in this respect, oil was placed in the treasure ,chest. Timber, of wide variety and in lavish quantity, covers the forests from tidewater to mountain slope, and within this protected watershed area flow streams which give the Pacific coast states the largest single share of the potential water-power resources of the country. Something over 40 per cent. of the total estimated horsepower of the United States is to be found in the Pacific states, and British Columbia has 15 per cent. of the total for Canada; but of this total less than 10 per cent. has been developed.

Jan 1, 1924

By M. D. Griffith

"Ventilation models are a vital tool to ensure ventilation designs can provide airflow to all work areas in a mine. Airway resistance and variations in natural ventilation pressures will affect simulated airflow and heat distribution through a mine. Validating ventilation model resistances and pressures to the exact underground conditions can be difficult and the variances can contribute to significantly different simulation results depending on the structure of the ventilation design. The study will use sensitivity analysis to explore examples of variability of simulated airflow due to small resistance, heat and natural ventilation changes and thereby help the user identify both trustworthy and potentially unreliable parts of a mine ventilation model. INTRODUCTION Mine ventilation network modeling is a vital tool for ventilation professionals and has become increasingly relied upon during the design and operation phase of mine ventilation systems. However, they provide only an approximation of reality, and caution must always be exercised when drawing conclusions or making decisions based on simulated data. Ventilation modelling should be performed by persons with a sound fundamental knowledge of ventilation and ideally should be validated with field data, but in large mines, or mines which are yet to be mined, accurate input of the simulation variables can be difficult, and errors and inaccuracies may be difficult or impossible to avoid. This study discusses and investigates the sensitivity of the mine ventilation simulation results to input errors. In addition, there are limitations to what steady-state airflow and heat simulations can model, regardless of the accuracy of the model inputs. In some situations, steady-state solvers cannot capture the dynamic changing behavior of a ventilation system. This study will also describe and apply techniques to analyze the natural variability of mine conditions on ventilation models. The consequences of poor accuracy in some parts of a mine model may impact on the health and safety criteria of ventilation designs. For example, if an airway is required to flow in a particular direction and quantity, then despite a ventilation model showing correctly designed conditions, small errors in input values may result in incorrect prediction of the direction or quantity of airflow. This may create unexpected buildup of heat or gases during operational activities, causing safety issues or operational delays. The ability to know which parts of a mine ventilation model have increased potential for poor simulation results will allow engineers to consider the ventilation design and make changes if required to better guarantee the required design flows."

Jan 1, 2019

By G. Dörsam, M. Spreij, S. J. Van der Wal, A. P. Schmidt

The transfer of hot metal desulphurising from the torpedo cars to the hot metal ladles at the IJmuiden BOS plant no.2 caused a decrease in ladle lining life from 680 to 470 heats. Changing the desulphurising agent CaC2 for CaO during a trial period, for environmental reasons, led to a further decrease in refractory life. Availability of the ladles became critical and the major reasons for the low life were identified. Solving one of them, temperature, quickly resulted in restoration of the original lives. However, re- introduction of the new desulphurising agent on 50% of the heats again resulted in a decrease, this time from 700 to 550 heats. In order to be prepared for the full introduction of the new agent, thorough investigation of worn linings was conducted, revealing the major (chemical) wear mechanisms. With these findings, a new design for the hot metal ladle is proposed.

Jan 1, 2004

By Miguel A. Cuba

Resource models are generally constructed using data of different types and/or from different sources. A common issue is the consistency of scale in the information that often leads to a requirement to composite the data prior to model construction. For the purposes of mine planning, development and/or resource assessment, this model may then be upscaled to a relevant selective mining unit. It is well established that the geostatistical parameters for resource model construction is scale dependent. In particular, the volume variance of integrating these various scales has a direct impact on the variogram that should be used in model construction and/or the assessment of volume variance relations as it affects resource estimation. The scaling laws are a set of guidelines that detail how the variogram should change as a result of a change in the volume; these laws are empirically derived and involve some simplifying assumptions, not the least of which is an assumption of shape invariance in the variogram structure. An alternative approach was proposed to directly upscale the variogram via numerical integration, which demonstrates that the assumption of shape invariance is not required and we can directly access the new variogram shape given any volume of interest. This paper compares these two different approaches to variogram upscaling by considering two applications: the first corresponds to a 2D synthetic case and the second looks at a 3D case with data from a porphyry copper deposit. The simulation studies in these cases show that the direct upscaling approach performs better than the scaling laws in fitting the average experimental variogram values at any block size. This is based on a mean absolute error criterion. Moreover, it is also shown that with an increase in the block size, direct variogram upscaling significantly outperforms the scaling laws approach.

Oct 1, 2009

By A. Alfantazi, M. Mahon

The current efficiency in zinc electrowinning is a key indicator of the performance in a cell house. This is typically measured by comparing the weight of the cathode to the electric current applied over the deposition period. This calculation can be cumbersome because the deposition history of each pulled set of cathodes will be unique. It will depend on the applied current and electrolyte conditions from onset of deposition until the cathode is removed and stripped. Not accounting for these can introduce errors to the calculated current efficiency. To track this history and reconcile the current efficiency, a time based computer process simulation was made of an industrial cell house. Two months of hourly recorded measurements from the cell house were input to the simulation, including current to the cell houses, concentrations, flow rate, and temperature of the purified leach solution. The simulation’s predictions of the concentration of zinc in the circulated, spent, and returned electrolyte all showed good agreement with the industrial data over the two months giving a validated zinc balance. The simulation was then tuned to predict the instantaneous current efficiency for all times, as well as the expected masses for the deposits given their deposition history.

Jan 1, 2014

By A. R. MacPherson

"This paper considers four aspects of autogenous grinding. Part 1 discusses statements on power efficiency of autogenous grinding compared to conventional crushing and grinding systems. It also demonstrates how high-power efficiency can be obtained from autogenous grinding systems. Part 2 considers a simple method of testing ores to determine the type of autogenous plant which can treat these ores on a commercial basis. A comparison of testing for simple small plants vs large plants or complex ores is included. Part 3 considers important aspects which have to be considered in proper design of an autogenous grinding system. Part 4 discusses problem ores and how they can be treated in an autogenous system. INTRODUCTIONAfter about 35 years of using autogenous grinding plants in the mining industry, it is perhaps time to review where we are with this, by now, relatively old development. Autogenous grinding in this paper means grinding run-of-mine ore by fully autogenous means or by using a ball charge to assist the grinding (semi-autogenous). Also, autogenous grinding can be eitherby dry or wet.The use of autogenous grinding in the fifties was making its slow start, and it was not until the sixties that more of the mining industry would consider its use . By the seventies, most builders of new plants would have considered autogenous grinding, whether they used it or not, in the final design.In the eighties, most large plants use autogenous mills and to reduce over-all operating costs, many older conventional plants are now looking and actually retrofitting these old plants with autogenous grinding mills.It is evident that many misconceptions concerning autogenous grinding are still current. Some come from improperly designed plants which result from poor test work. There are many considerations in the proper design of autogenous plants. Some ores have been found to give problems even in a well designed plant. These ore types are beginning to be classified and recognition in the test stage allows steps to be taken in the design so that these ores can be efficiently handled in autogenous grinding plants.Therefore, this paper will address the following aspects of autogenous grinding:1. Misconceptions regarding autogenous grinding.2. Testing of ores to ensure a well designed commercial plant.3. Important considerations in mill design.4. Difficult ores, their recognition and types of design to handle such ores."

Jan 1, 1989

By E. Gervais

"In today's marketplace, heavy competition between materials is the norm. This is particularly true f or the base metals, which are being increasingly challenged by new or improved materials in all traditional applications. Current usage of base metals results from a combination of a metal's intrinsic properties, and technology. The future of the base metal industry rests with innovative, high-quality product development, its ability to take advantage of the results of worldwide, massive material R&D investments, and with the dynamism and effectiveness of its market development programs.The ZA casting alloys program is an illustration of the zinc industry’s efforts to protect and expand its market position in the casting field through state-of -the-art technological developments. The market potential f or these advanced engineering alloys is substantial, and their impact on traditional zinc die casting alloy consumption is particuarly important. The ZA alloys, in offering increased performance through zinc castings produced at low cost and by a wide range of moulding processes, have unlocked a multitude of new end-use applications.Following a review of the development of ZA alloys, of their key properties and of their performance characteristics, the numerous challenges that the alloys present to the zinc industry and to the R&D community are discussed.IntroductionZinc is anodic to steel and has a low, uniform rat e of corrosion; it has a low melting point, can be cast with precision , and is readily finished. In addition to its use in protecting steel and in the production of a wide range of castings, zinc is employed : (1) to produce brass, high-strength aluminum alloys and magnesium die casting alloys, (2) in the wrought state for coinage and in building products, particularly as roofing materials , and (3) as an oxide, in the rubber industry, in ceramics, glass, cosmetics, pharmaceutical products and as the starting materials for many chemicals.Zinc die castings are produced with accuracy at high speed, at low cost, are easily finished and have excel1ent mechnical properties . Car fuel economy, changes in automobile styling, competition from other materials, increased sophistication of design and miniaturization have all led to a dramatic change in the volume of zinc consumed for die-casting applications. This has been particularly notable in the United States. Throughout the 19505 and the I960s, casting was the fastest growing major use of zinc; it was firmly established, accounting for 35% of the total zinc consumption(1), By 1983, the volume of zinc being purchased for casting applications had dropped to less than 20% of all zinc consumed in the United States. In the western world(2), consumption for zinc casting application s is currently at about 15%; being nearly equal to the zinc consumed by the brass industry. Coating applications dominate with a consumption of more than 40% of the total market."

Jan 1, 1987

By T. G. Joseph, A. Sharma

ABSTRACT: Ultra-class haul trucks operating in oil sand face operational and maintenance issues as a result of soft underfoot conditions (Joseph, 2002). With exposure to frequent high g loading events, tire life is reduced due to sidewall belt fexure and frequent ground contact. Therefore, an improved under-standing of the interaction between tires and oil sand is needed. This paper examines the outcomes of a series of static and cyclic loading tests, performed using a scale tire on rigid, sand, and oil sand surfaces. Geometric predictions are made regarding the footprint area and vertical deformation of an ultra-classtire on similar surfaces.

Jan 1, 2011

By N. B. Brown

ABSTRACT The effect of a low4emperature stress relief at 232.2°C. (450°?F.) on the fatigue properties of shot-peened SAE. 1080 steel has been investigated. Specimens of the steel were first annealed. One half of the steel bars were then normalized and the other half were water-quenched and drawn. Specimens of the steel with each heat treatment were tested in tensile, notched bar impact, and fatigue. The fatigue specimens were test in air and water in R. R. Moore high-speed rotating bending machines in the following conditions: un-peened, peened, and peened-and stress-relieved at 232.2°C. ( 450°F.) The 'endurance life' and fatigue properties of specimens given a stress relief heat treatment after shot peening were superior to those of specimens given a smooth machine finish or shot peened. INTRODUCTION THIS investigation was initiated to obtain preliminary information on the effect on the fatigue resistance of shot peening the machined surface of a high-carbon steel similar in composition to that used in hollow drill steel. The data obtained in this investigation could be applied in analysing the application of shot peening hollow drill steel shanks. It is well known that the 'endurance life' and fatigue limits of steel are greatly ?improved by shot peening. References to this in the literature are numerous.

Jan 1, 1951

By B. L. Moreau

Certain gas wells tend to form hydrates in the production tubing. This paper outlines a method developed and used by the Author's company to overcome the problem. The injection of glycol to control hydrates results in sufficient dehydration to allow the gas to be trans-ported through a field-gathering system b a treatment plant. Sub-surface injection of glycol also offers a method of introducing corrosion inhibitors into the gas stream. The major operating difficulties have been overcome and the system is now in use in the northeastern part of British Columbia.

Jan 1, 1958

By A. Atef

Vulnerability is a measure of the extent to which a community, structure, services or geographic area is likely to be damaged or disrupted by the impact of particular hazard. Current asset management practices focuses on studying factors that affect performance of isolated infrastructure networks and model a set of actions to control the expected performance of these networks. This approach ignores the underlying spatial and functional interdependencies among these infrastructure networks and their vulnerability. The purpose of this paper is to introduce a new method that recognizes the effect of spatial and functional interdependencies on vulnerability rating of water, sewer and road networks. The proposed method consists of: 1) risk assessment model, 2) interdependency assessment model and 3) vulnerability assessment model. The risk model is composed of two modules: 1) water and sewer risk module and 2) road infrastructure module. The water and sewer risk module will cluster these assets into three risk categories based on environmental, social, operational and economical factors. The road infrastructure module will cluster road assets into three risk categories by using rational factorial technique based on road type, serviceability index, traffic load, and freeze and thaw index. The interdependency model will deploy the risk ranking to perform geospatial analysis in ArcGIS which results in determining the interdependent layers of waters, sewers and roads. The vulnerability model will deploy fuzzy neural networks technique to determine the vulnerability rating based on spatial and functional interdependencies. The fuzzy neural networks are utilized to overcome the lack of historical data and incorporate experts? preferences for establishing the knowledge base for vulnerability assessment. The expected contribution of this framework is to aid decision makers in understanding the interdependencies between civil infrastructure assets and to which extent such interdependencies can compromise assets performance.

Aug 1, 2013

By Oberlando Gonzalez, Claudia Serna, Andrea Alzate, Esperanza López, Maria Holuszko

This paper presents a systematic approach on gold recovery from electronic waste (e-waste) using ammonium persulfate. This process was developed as a response to the lack of hydrometallurgical systems capable of separating gold from its metallic substrate without material grinding, with minimum formation of pollutants, and achieving a lower reaction time. Computer memory boards, electronic processors and electronic pins and contacts were analyzed to determinate base metals (Ni, Fe, Cu) and gold (Au) using microwave plasma atomic emission spectroscopy (MP-AES). An aqueous commercial grade ammonium persulfate with oxygen and pressure was used to produce the persulfate anion (S2O82-) and the oxidative sulfate ion (SO42-), which partially oxidized and leached the base metals breaking the Au-Ni-Fe-Cu bonds and allowing gold to be recovered in its original non-leaching state. The influence of the oxidative parameters was evaluated using full factorial (FF) and central composite designs (CCD) with response surface methodology (RSM) and first and second order models were developed. Using RSM allowed to obtain a faster recovery of gold, minimizing the agent consumption. The findings presented suggest that optimized quantities of ammonium persulfate, oxygen, pressure, temperature and liquid solid ratio could be used for selective oxidization of the base metals and to extract more than 96% of gold from e-waste.

Jan 1, 2017

By WENDY MARTIN

The Eastern Townships and Asbestos Hill areas are the current asbestos-producing districts of Quebec. Mining in the two areas began in the /are 1870s and 1972 respectively. Production from the Eastern Townships is derived from rhe Serpentine Zone of ulrramafic rocks, specifically from basal serpentinized peridotite members of what are now considered to be allochrhonous ophiolitic material that was abducted onto the Early Ordovician continental margin. From south west to northeast, the rhree allochthonous asbestos-producing sections of the Serpentine Zone are designated the Asbestos Ophiolite Complex, the Thetford Mines Ophiolite Complex and the Pennington Dyke; the Pennington Dyke is considered to represent a segment of serpentinized Alpine peridotire that was fragmenred from a larger, more complete ophiolire complex. The Asbesros Hill deposir on the Ungava Peninsula lies in what apparenrly is an inrrusive sill found wirhin rhe Chukorar Group, the uppermosr group of Precambrian-aged Cape SmithWakeham Bay Belr of volcanic-sedimentary rocks.

Jan 1, 1984