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By Jamal Asfahani

Abstract - Natural gamma ray well logging, an effective tool in geophysical prospecting, is used to investigate the radioactive and phosphatic layers in the Khneifiss mine in Syria. The interpretation of the gamma ray measurements, using numerical methods of analysis developed previously and applied successfully in some phosphatic areas in Syria, make it possible to define precisely the phosphate thickness from place to place in the study area. This technique has been successfully applied while studying seven boreholes in the area. Sixty-three core samples from phosphatic layers in the boreholes have been analyzed, using gamma ray spectrometry for the determination of P2O5 , U, Th, and K. Good correlation between P2O5 content and U concentration has been found. The total count gamma logs correlate reasonably well with the U core analysis, suggesting that radioactive equilibrium exists in the U decay series. These gamma logs can be therefore used effectively to quantitatively map the distribution of P2O5 and U. The characteristics of both subsurface phosphatic sand and phosphatic rocks have been investigated and outlined using a statistical approach. The affinity of uranium to some trace elements such as V, Sr, Cu, and Ni has been verified using correlation matrices of these elements.

Jan 1, 2002

By A. Jeffkins

Visibility is restricted when operating load haul dump vehicles resulting in a number of serious accidents in the Ontario Mining Industry. One of the leading causes of these accidents is the inability of the equipment operator to see clearly people, objects or hazards around the machine. Previous line of sight testing by the research team found specific machine characteristics were responsible for blind spots and impaired visibility. In order to identify feasible design modifications a computer simulation program, Classic JACK 3.1, was utilized. Program features include human factors analysis, which allows evaluation of line of sight and operator posture in order to decrease risk of musculoskeletal injury. Research within the virtual computer environment consisted of a Visibility Audit and a Target Audit in order to quantitatively determine how certain components of the LHD design affected the line of sight around the vehicle. Results indicate that modifying the LHD light brackets, engine profile, cab posts and other components will enhance visibility. The addition of cameras located on the front and rear of the vehicle were able to enhance the operator?s sight lines to previously obstructed areas. Modifications to seat height and the operators orientation both improved sightlines and decreased risk factors associated with back and neck musculoskeletal disorders.

May 1, 2003

By Tiago Webber

Mineral resources estimation comprises basically two stages: (i) data collection, analysis and validation, and (ii) the estimate of the grades and tones of the deposit. The most applied method for sampling survey in mineral exploration is rotary drilling with total core recovery. High drilling costs make borehole geophysical logging attractive to obtain the maximum possible information from each borehole helping to understand ore intersections, grades variability, limits of the deposits and continuity of the mineralization. In this paper, borehole geophysical logging was used to enhance the sampling survey and to derive grades indirectly (without lab analysis) with a certain amount of uncertainty. Indicator kriging (IK) was the estimation method used, as it is adequate to incorporate the uncertainty associated with the geophysical derived grade values. The results were compared to the conventional procedures using grades determined via core analysis and ordinary kriging. Borehole geophysical logging proved to be efficient to define the essential features of ore deposit and IK provided results with acceptable precision and accuracy if compared to the model provided by ordinary kriging.

Oct 1, 2009

By S. M. Bulatovic, D. M. Wyslouzil

"This paper presents the results of a study of the effect of flowsheet configurations on metallurgical results and describes a general method for developing and optimizing flowsheets used in the treatment of massive sulphide ores. The flowsheet configuration can have a significant effect on recovery and selectivity between valuable minerals and gangue minerals. Placing of intermediate products within the flowsheet, positioning of various pretreatment units, such as conditioners or regrinding mills, and the ability of the flowsheet to cope with wide swings in the feed grade and composition are the major parameters that determine the optimum flowsheet configuration. The complexity of the flowsheet is largely a function of the ore itself and of the number of final, marketable products that have to be recovered from the ore. INTRODUCTIONTechnological ExpansionThe trend of past decades has been towards larger equipment and a better understanding of the chemistry of the flotation process. Despite appreciable progress in these areas little attention was given to the study of the actual configuration of the flowsheet, although the arrangement of the flotation equipment significantly affects the overall performance of the circuit."

Jan 1, 1989

By J. H. Pateson, D. C. Comrie, D. J. Ritcey

"Geopolymers are inorganic semi-amorphous three dimensional silico-aluminates of the poly(sialate) type (-Si-O-Al-0-) or of the poly(sialate-siloxo) type (-Si-O-Al-O-Si-0-). Polycondensation occurs at low temperatures with geopolymers being stable up to 12oo0 c. Research, development and application technology pertaining to geopolymers is being undertaken jointly with Dr. Joseph Davidovits of The Institute for Applied Archaeological Sciences of Florida, U.S.A. This joint focused upon the chemical Barry University in Miami Shores, research and development program has stabilization and solidification of various waste products through geopolymerization. Of particular interest is the geopolymerization of mine wastes including tailings and waste rock derived from the processing of base metals, precious metals, potash, coal and uranium deposits.INTRODUCTIOND. Comrie Consulting Ltd., in cooperation and technical liaison with CANMET, Ottawa has been testing the application of geopolymers to mining wastes. Corporate efforts to date have concentrated upon reactive acid tailings, principally from the abandoned Kam-Kotia Mine site, and dewatered paint waste sludges. Test work conducted to date has successfully yielded geopolymer treated materials and wastes with increased chemical and structural stability. Wastes containing heavy metals, cyanides, arsenic and sulphur dioxide have been successfully geopolymerized."

Jan 1, 1988

By J. W. Keyes

"The original grinding circuit at East Malartic consisted of two 8 by 8 C.A.C. mills in closed circuit with two 72 inch Akins Classifiers and an 8 by 10 secondary mill in closed circuit with two 48 inch duplex classifiers. With this circuit, we experienced a drastic drop in tonnage from one month to another, due to variations in the hardness of the ore. The first step to overcome this difficulty was made by increasing the critical speeds of the mills from 78% to 82%. This resulted in an increase in the secondary mill throughput; but, when the change was made on the primary mills no increase was obtained.The drastic drops in tonnage were still experienced and through working with Allis Chalmers the 8 by 10 mill was converted to a rod mill and the two 8 by 8 n1ills to secondary mills. This change eliminated the two 72 inch Atkins classifiers and the scoops on all the mills, since the 48 inch Akins classifiers sands could then be fed by gravity to the secondary mills through feed pipes.The rod mill and secondary mill discharges were fed to a common pump box using 5 by 5 S.R.L.'s running at 1085 R.P.M. with a twenty-five foot head. When this was done the pumping costs jumped from $105. 00 for 6 months to $1050. 00 in one month, or from 0. 0004 to 2. 75 cents a ton milled. Several factors contributed to this jump in pumping costs as follows:"

Jan 1, 1964

By A. L. Hinde, H. Dong, J. T. Kalala

"The High Pressure Grinding Roll (HPGR) is gaining acceptance in the mineral processing industry and has become a competitive technology in reducing the specific energy consumption in Mineral processing plants. The amount of samples required for HPGR amenability testwork and HPGR wear tests is usually high and often cannot be available at early stage of projects were only a few drill cores are available.Although HPGR was initiated from small scale piston die compression tests, the development of small scale piston die test to predict the performance of HPGR has been slow.The objectives of this paper was to present the designs, operating procedure of piston-die press and operating conditions which have resulted in similar particle size distribution obtained from a piston die test and HPGR Labwal unit starting from the same feed size distribution. Testwork were conducted using a 2 MN piston-die press and a Labwal HPGR unit on major South African ore types, viz, gold, platinum and iron ores. The results obtained show that piston-die test can generate data to predict energy consumption, product size distribution, and even to evaluate the edge effect."

Jan 1, 2012

By R. C. Snider

The Roy Lloyd Mine in northern Saskatchewan is a high-grade underground gold mine which is currently supplying ore to Golden Band Resources Inc. (Golden Band)?s Jolu mill. Prior to the operation of the mine, an underground exploration program was conducted intermittently at the site. During both the underground exploration phase and mining, Golden Band has implemented water recycling to reduce freshwater usage within the mine in order to address concerns over the potential for impacts associated with freshwater usage and to reduce the volume of effluent discharged from the site. Golden Band initiated an underground exploration program at the Roy Lloyd Mine site (formerly called the Bingo Project) in October 2007 to better delineate the mineralization of the Bingo gold deposit. The exploration program provided geological information required in order to improve the confidence level of the geological resource model and also provided information to aid in the mining of the deposit, such as the determination of groundwater inflow rates. Underground production mining started in March 2011. This paper provides an overview of the mine water recycling methods implemented at the site during both the exploration and initial mining phases of the project, and the success/drawbacks of these measures to date, including the potential cost savings in the form of reduced treatment and monitoring costs inherent in a reduction of the volume of effluent discharged from the site. The paper will also discuss options that are currently being evaluated in order to further assist Golden Band?s ability to recycle water and reduce the volume of effluent discharged to the environment, while ensuring effluent discharged from the site to the environment meets criteria.

Nov 1, 2011

By Gema Ribeiro Olivo

The hydrothermal Au-Pd deposits are hosted by the jacutinga in the Lake Superior-type iron-formation of the Itabira Group, Minas Supergroup. Jacutinga is a highly sheared, metamorphosed, hydrothermally altered iron-formation composed of hematite, magnetite, quartz, talc and phlogopite (Cauê) or muscovite (Conceição) and minor tourmaline, palladian gold, arsenopalladinite, mertierite II and palladeisite (hydrothermal) and native gold, native palladium Pd-Cu-oxides, and kaolinite (weathering products). The highest concentrations of Pd-Au occur in quartz and hematite veins parallel to the S1 foliation (Corpo Y, CorpoX, Aba Leste and Central orebodies, at Cauê and a single orebody at Conceição) or parallel to the S2 foliation (Aba Norte). The average ore grade is 30-40 g/t Au+Pd. The characteristics of the Au-Pd ore favor an epigenetic model for gold and palladium concentration in the iron-formation. During the D1 deformation and peak metamorphism, the oxiziding, acid and hot hydrothermal fluids transported Au and Pd preferentially as chloride complexes. The reaction of the fluid with the dolomitic carbonate (the probably protolith of the jacutinga) would have dissolved carbonate and K-feldspar to form muscovite or phlogopite and tourmaline, resulting in an increase in solution pH and a decrease of Cl concentration and subsequent deposition of gold and palladium minerals.

May 1, 2003

By E. J. Marcotte

"BRIEF DESCRIPTION OF GRINDING CIRCUITCrushed ore at -5/ 16 in. is delivered by a conveyor system from the crushing plant to two 1250 ton fine ore bins. The ore is transferred from each bin by a 30 in. feeder conveyor belt, operated by a Link Belt P.I. V. (variable speed) drive, to a 24 in. conveyor that feeds the 8 x 10 Allis Chalmers rod mill.The rod mill discharges to a common mill discharge pump box. Three 6 x 6 SRL pumps are employed to pump the combined mill discharge pulp to a common distributor box which distributes the feed to two of the three Kreb D lSB cyclones in each of the two banks at a hydraulic pressure of 6 psi.The cyclone overflow at a specific gravity of 1. 25 (i.e. 32% solids) is transferred by gravity to two revolving chip screens for wood chip removal and from there to a pump box. Two 5 x 5 SRL pumps feed the pulp to the thickeners. The underflow from the cyclones is fed to two 8 x 8 Allis Chalmers ball mills which discharge to the common mill discharge pump box. Thus, a closed circuit is formed between the ball mills and their respective bank of cyclones. The circulating load as most recently calculated is 262%."

Jan 1, 1966

By M. Takebayashi, K. Takenaka, S. Matsubara, T. Yoneyama

The cathode production of Toyo Smelter and Refinery, owned by Sumitomo Metal Mining Co., Ltd. reached 450,000 tons per year in 2016 with three tank houses. Niihama tank house commenced operations in 1919 with conventional sheet cathode technology. Approximately 100 years of operation experience and the technical development enabled that the current density of Niihama tank house and the Toyo tank house #1 increased to 320 A/m2. These operation techniques were utilized at the Toyo tank house #2 which started in 2005, and its current density reached up to 350 A/m2 with permanent cathode technology. In order to achieve high current efficiency under condition of 350 A/m2 operation at Toyo tank house #2, continued efforts had been made to verticality of anodes and permanent cathodes. To improve verticality of anodes and cathodes, reduction of short circuit ratio by changing the shape of the anode, optimizing the anode pressing machine and off-line process for rectifying the distortion of permanent cathodes was carried out. In addition, concentration control of electrolyte and expansion of Ni removing ability from the electrolyte prevented passivation. Finally, more than 96% of the current efficiency was stably confirmed. INTRODUCTION Today, Toyo Smelter and Refinery of Sumitomo Metal Mining operates three tank houses in Japan, namely, Toyo tank house #1, Toyo tank house #2, and Niihama tank house with a total capacity of 450,000 metric tons of copper cathodes. Figure 1 shows the trend of cathode copper production and the current density at three tank houses over the last 10 years. Cathode production by Toyo Smelter and Refinery reached 450,000 tons per year in 2016 with three tank houses.

Jan 1, 2019

By Caitlyn J. McKinley, Ahmad Ghahreman, Maziar E. Sauber

Ever-growing global needs for critical metals, such as rare earth elements (REE), and base metals, such as copper and nickel, and their environmental impact motivated the pursuit of sustainable flowsheets. Regeneration of hydrochloric acid in chloride-based leaching flowsheets as a critical unit operation is an example of such endeavours. This study presents an efficient hydrochloric acid regeneration method from a magnesium chloride solution waste by addition of sulphuric acid in relatively low temperatures. The effects of temperature, initial magnesium chloride concentration, amount of sulphuric acid added, and airflow are examined. Experimental work are focused on temperatures between 80 and 95°C, initial magnesium chloride concentrations of 2 to 5 M, 100% to 220% stoichiometric sulphuric acid additions, and airflows between 200 to 600 mL/min. The developed technology recovers hydrochloric acid at a high rate and concentration with a relatively small environmental footprint. INTRODUCTION The mining and metals sector is under increasing environmental and economic pressure to make more efficient use of chemical reagents and energy in the production process. This affects several areas of process and flowsheet design such as the selection of the most appropriate unit operations and the overall design of the process steps paying heed to sustainability. Owing to the inherent inefficiencies of physical and chemical processes used in the mining industry, there will be materials and streams generated that are not a desirable part of the envisaged flowsheet. Thus, methods are implemented to recover and recycle such effluents. If the recovery and recycling are not economical, then procedures are followed to neutralize and dispose these effluents. In many cases, these effluents are potential contaminants or hazardous materials, and their disposal should be looked at in a much larger context. The safe management of the contaminants and hazardous effluents is a daunting problem in the mining industry and is fraught with technological, economic, social, and political challenges.

Jan 1, 2019

Grinding with an electrochemically inert grinding media (i.e. high chrome white iron, or Magotteaux’s Duromax® alloys) shifts the pulp potentials to more oxidising conditions, increases the dissolved oxygen content and reduces the EDTA extractable iron concentration when compared with milling with electrochemically active grinding media (forged steel). These changes in pulp chemistry produce cleaner particle surfaces, reduce reagent consumption and increase concentrate grades and recoveries. This paper presents a robust laboratory test program that is able to not only demonstrates these effects but also provide an indication of the magnitude of the improvements that are possible. While laboratory studies are interesting, the proof is in the pudding! So, the paper provides an overview of plant trials conducted at a number of operations around the world, including: Newcrest’s Cadia Operation, Oz Minerals’ Prominent Hill Mine and Glencore’s Ernest Henry Mine. These successful plant trials clearly demonstrate that selection of the right grinding media alloy will yield savings in grinding media consumption and reagent consumption as well as increases in revenue through improved copper, gold and molybdenum recoveries. INTRODUCTION The key to a successful separation in mineral processing is the preparation of particles with adequate liberation under the correct pulp chemical conditions. While the importance of liberation on flotation separations is generally understood and well documented in the literature (Johnson, 1987; Jackson, Sutherland, Gottlieb & Quittner, 1989; Young, Pease, Johnson, & Munro, 1997; Greet and Freeman, 2000), the importance of pulp chemistry is more nebulous, particularly with regard to the impact of grinding media. Extensive work examining the electrochemical interactions between grinding media and sulphide minerals has been completed (for example, Iwasaki, Reid, Lex & Smith, 1983; Natarajan and Iwasaki, 1984; Yelloji Rao and Natarajan, 1989(a); Yelloji Rao and Natarajan, 1989(b)). Broadly, these studies indicate that most sulphide minerals are more noble than the grinding media used during comminution, therefore a galvanic couple between the media and the sulphide mineral(s) exists, which increases the corrosion rate of the grinding media. The corrosion products of the grinding media, iron oxy-hydroxide species, invariably precipitate on to the surfaces of the sulphide minerals thereby affecting their floatability (Johnson, 2002).

Jan 1, 2019

By A. F. Banks

"IntroductionThe typical potash processing plant recovers and/ or upgrades from 10% to 20% of its production through the recrystallization process. The feed to the recrystallization section consists of preconcentrated slurries of fine crystal size that cannot be raised to the required product grade by flotation and fine dusts also of low grade and too fine for compaction feed. It produces high grade white potash crystals that can be marketed as a high grade product or blended into the flotation products to raise their grade. In this chapter, a typical leaching (dissolving) and recrystallization operation will be discussed.The crystallization process makes use of the three phase system chemistry of NaCl, KCl, and H,O. The normal potash process operates on a temperature range of 75°F to 95 °F. A three phase slurry feed to the dissolving circuits will be within that range. The potash (KCl) is dissolved by heating the slurry in the presence of sufficient brine to a temperature of 190°F to 200°F. As the slurry is heated, the potash (KCI) dissolves and the salt (NaCI) precipitates. The potash rich brine is then clarified and the salt and other undissolved solids removed by thickening. Clarified brine becomes the crystallizer feed.The hot brine is cooled in evaporative cooling crystallizers. In cooling, the potash precipitates as a high grade white crystal. Crystallization is done in multiple effects to permit energy recovery and control of the process. In a four effect crystallizer the cooling is done by recycling mother liquor counter currently through the first two effect condensors and using brine pond brine for the cooling of the last two.The crystallizer product is removed from the last effect as a slurry at normal process temperature and is fed either to its own centrifuging and drying circuit or blended with the flotation product for centrifuging and drying."

Jan 1, 1989

By D. Eriksen

Zero Emission Gas power, ZEG, is a novel concept where a high temperature solid oxide fuel cell (SOFC) is integrated with a reforming reactor producing hydrogen from natural gas through Sorption Enhanced Steam Methane Reforming (SESMR). The SOFC is used as a high temperature heat source for regeneration of the CO2-absorbent. Moreover, by using part of the produced hydrogen as fuel for the SOFC, the waste heat of the process is considerably reduced. Thus, the process has a very high thermal efficiency and produces both electricity and hydrogen from natural gas. In addition, a stream of pure CO2 is produced in the regeneration step and can be deposited or used commercially. Initial cost estimates indicate a cost of electricity and a cost of hydrogen well below today's prices. A small (1kWel + 1kW H2) demonstration set-up is under construction and experimental results and related research will be presented. This set-up comprises one 2.5kWth H2 SESMR-reactor (about 0.85 Nm3/h H2) operating batchwise with dolomite as the CO2-sorbent. The reactor developed is designed like a parallel plate heat exchanger where the mixture of sorbent and reforming catalyst is packed between the heat exchanging plates. The demonstration set-up includes a 1kW SOFC operating in a continuous mode. The set¬up will therefore demonstrate continuous simultaneous hydrogen- and electricity production, but cannot demonstrate simultanuous electricity- and CO2-production. The set?up is well equipped for on-line monitoring of gas composition, flows and temperatures. This important part of the demonstration set-up is developed and provided by Christian Michelsen Research (CMR). A minor part of the project is the development of a continuous circulating fluidized bed SESMR-reactor system and in another related project the focus is on the development of more suitable sorbents. In these two projects co-operation with University of British Columbia and Lousianna State University, respectively, is highly appreciated.

Jan 1, 2005

Everybody would agree that a good roadway leads to more efficient haulages by reducing haul times, smoother and safer operation for operator and less wear and tear on tires and equipment, thus improving availability and overall costs efficiency. There is a number of factors that come into play to achieve this especially when developing a mine. Excavations of Ramps and Headings: Operators should follow surveyors and layouts accurately while driving ramps. To maintain constant grades on ramps, which leads to better design control of water and easier grading of roadways. Dips and dives lead to needless over excavations and unnecessary cost and disposal of waste rock. When dressing a ramp some areas may require 2 to 3 feet of material to correct the dips and perfect to constant grade. You may ask yourself, is this all necessary? A small exercise is to follow a loaded haulage truck up ramp. At the first hump, grade change, notice the down shift and notice how far the truck travels to regain the up shift and his speed. The difference is remarkably noticeable when the grade is constant. All this leads to less driveline shock, less horsepower demand, better fuel efficiency and more productivity. Drill & Blast Patterns to control water for Ramp Headings: The drill pattern needs to allow for a ditch. A slight cross fall to form a ditch can easily be done with the lifters. The preferred side of the ditch is always the inside curve of the ramp as it has less tendency to erode roadbed material. On a level, the ditch is dictated by the sump location. A blasted ditch will eliminate water pounding and keep the roadbed dry. Water trapped in roadbed is the major cause of rollout and de-stability of roadbed. If the water is allowed to drain in the middle of the ramp it will cause erosion, movement and loss of fines and an increase in grading intervals.

Feb 1, 2008

By G. Agar

"E. Joe We have been working for some years on the elimination ofCANMET thiosulphates from solutions as a means of protecting ground water and fish streams. Alot of these thiosulphates result from the mill use of S02. Is there any possibility that thiosulphates will be generated by this process?Reply I don't know the answer to your question. I can speculate that there is no question that when one adds SO2 and air to a sulphide pulp one generates a host of unsaturated poly¬cyanates. I unfortunately cannot remember the reactions which arise in the cyanide destruction scheme. I think that if thiosulphate was generated the process wouldn't work. It is not oxidizing enough to destroy the cyanide.R. Wagner Would you comment on the actual cost/ton at the Scottie goldPamour mine concentrator? Would $2.50/ton be typical or is thisPorcupine just a ball park figure.Reply We wouldn't disclose Scottie's costs even if we knew them. I depends on the amount of cyanide and thiocyanate in the effluent. I have given you a hypothetical case. With the conditions stipulated the figures I Have given are realistic.K. Konigsmann I do not believe the use of S02 adds significantly to the thio Noranda Mines salt problem Certainly we use SO2 in many of our mills and thio-salt levels in a number of them haven't changed whether we use or don't use S02. For instance, Orchan and Matagami mills treating the same ore side by side in which one was using S02 and the other wasn't, the thio-salt level was virtually the same in both pulp streams. In the case of Brunswick where alot of SO2 is used (20 tons/day) there is a thio-salt problem but it is relatively insignificant.Reply Thank you for that comment. It serves to reassure us that we are not polluting the environment."

Jan 1, 1984

Polymer electrolyte membrane (PEM) fuel cell has increasingly become the potential choice of zero-emission power source for portable, mobile and stationary co¬generation applications. However, technical barriers need to be overcome before its widespread commercialization; cost reduction and performance improvement including reliability are the two key areas, that can be realized through better cell/stack design and improved understanding of the transport processes occurring inside the individual cells and stacks. In this presentation, we will provide an overview of various cell/stack models that are available in the literature, their strength and weakness, and then present a comprehensive multi-species, multi-phase and multi-dimensional formulation of a single PEM fuel cell, with consistent and systematic formulation for all the regions involved, including the solid bipolar plates, gas flow channels, the electrode backing layers, the catalyst layers and the electrolyte membrane. Such a detailed approach allows us to extract sufficient information to the analysis of a stack of PEM fuel cells. Stack model will be presented that investigates the various stack designs and flow configurations, and the optimal stack design based on the present study will be described. Also some innovative cell/stack designs will be featured.

Jan 1, 2005

By M. Lundström

The Outotec HydroCopper® process is a novel technology, developed and registered by Outotec Technology Oy, for leaching copper from chalcopyrite using cupric chloride solution. The leaching process is operated at atmospheric pressure in a stirred tank reactor, at temperatures near the boiling point of water and pH values between 1.5 and 2.5. During the leaching of chalcopyrite in cupric chloride solution, a reaction product layer forms on the mineral surface. In the present work, the formation and the composition of the reaction product layer was studied in an environment similar to that of the HydroCopper® process. The effect of the process parameters on the reaction product layer was investigated. Electrochemical measurements, including A.C. impedance spectroscopy and microscopic observations were carried out and an equivalent circuit was used to determine the surface parameters, such as the reaction product layer capacitance and the charge transfer resistance. The results suggest that, at low pH, a passivating sulfur-rich layer forms, whereas at high pH, a more porous iron-rich layer was detected. The values measured can give useful information for optimising the leaching parameters of the HydroCopper® process. Cu2007

Jan 1, 2007

By H. Saari, M. Pates, P. C. Patnaik, A. Merati

Single crystal nickel-base superalloys such as PWA1484 exhibit superior performance compared to conventional superalloys, and are used extensively in turbine blade applications requiring good high temperature properties. The life of these blades is typically limited by cracks and erosion. Due to the high cost of these blades, welding techniques are being considered to weld/repair worn components, extending their useful lives and delaying the need for expensive replacement components. However, the sensitivities for solidification cracking and post weld heat treatment cracking are relatively high in these alloys. Electron beam (EB) welding can deliver concentrated heat sources and has the potential to address these issues. Numerous welding trials and structural tests must be conducted to identify the optimum method and welding parameters. Weldability is studied over a range of material conditions, welding parameters, and directions. The influence of welding parameters on the fusion zone microstructure and resultant weldability is investigated using combination of microscopic examination and micro-hardness testing. This paper summarizes some of the results of a feasibility study conducted to understand the effects of welding parameters on localized microstructural features, cracking sensitivity, and mechanical properties of autogenously EB welded coupons of single crystal PWA1484.

Jan 1, 2004