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By E. L. Bruce

EUROPEAN Russia is mainly a great plain, the average elevation of which is only 600 feet above sea level and the maximum elevation less than 1,200 feet (Figure 1). The main divide between the Arctic ocean and the Black sea and Caspian sea is an indistinguishable topographic feature from which the Dneiper and Don rivers flow southward to the Black sea and the Volga river to the Caspian. The valleys of these rivers are but little below the general level (Figure 2). To the south, this great, rolling plain is broken by a low ridge of Precambrian gneisses and intrusive rocks. The Crimea is an upland from which the descent to the Black Sea coast is precipitous (Figure 3). The Ukrainian Soviet Socialist Republic occupies the southern part of the plain. It is the southwestern unit of the Union, bordered by Rumania and Poland on the west and by the Crimean Soviet Socialist Republic on the south.

Jan 1, 1938

By Miguel A. Cuba

Trends in the mean and/or variance are a longstanding challenge in mineral resource modeling. Geologic modeling and/or grade domaining are often employed to account for heterogeneities in mineral grades; however, this is only practical up to a certain point since the number of data available for reliable model construction can be severely reduced. In such cases, trends remain present in certain geologic/grade domains and directly impact the modeling methodology; the trend must either be handled explicitly or a suitable approach is adopted to implicitly account for it. This is highly dependent on understanding the source of the trend. We propose an approach that detects the source of non-stationarity, which is based on quantifying the impact of non-stationarity in the mean and the variance via the semivariogram. By expanding the methodof- moments approximation of the semivariogram, we decompose the experimental semivariogram is into three terms: 1) trend in mean component, 2) trend in variance component and 3) stationary component. We can then assess the source of trend by calculating the contribution of each component at every lag. Two cases are presented to illustrate this tool. Firstly, a synthetic reference model is simulated and different trend patterns are added; the influence of these patterns in the experimental semivariogram calculation are analyzed and discussed. Secondly, a real dataset is considered where the impact due to the presence of trends in the mean and variance are assessed. The results of this paper reveal the semivariogram to be a tremendously powerful tool in determining the source of the trend. This insight may be useful in the selection of a suitable modeling approach for resource estimation.

Oct 1, 2009

By Isabel C. B Rodrigues, Flávia D. Reis, Versiane A. Leão, Rosa M. F. Lima

Attention has been focused in recent decades upon the precipitation of metal sulphides from acid mine drainage (AMD) and pregnant leach solutions, due to the advantages of the sulphide precipitation process over traditional methods employing hydroxides. The aim of this work was thus to explore technologies for copper precipitation using either Na2S or biogenic sulphide. The recovery of copper sulphide was improved when the initial pH of the solution containing each metal was 4 or excess sulphide was employed. In such, a condition the removal efficiency was 99.9%, corresponding to a residual level of 0.1mg/L for copper in solution. Kinetic parameters for precipitation were determined from the particle size distributions using the method of moments, where the growth and nucleation rates, as well the agglomeration kernel, were calculated. The biogenic sulphide was a suitable alternative to sodium sulphide for copper removal as either sodium sulphide and biogenic sulphide can be utilized to precipitate such a metal allowing the effluent to be compliant with environmental legislation.

Jan 1, 2014

By John Lund

INTRODUCTION GOLD-BEARING placers of Alaska and the Yukon Territories are buried under a layer of permanently frozen alluvial overburden, or 'muck', which varies in depth from twenty to one hundred feet. The placers, and the decomposed bedrock layers upon which they are deposited, are also permanently frozen. During the summer, surface muck which is exposed to the sun will thaw, but only to a depth of a few feet. To reach a valuable deposit, the frozen overburden must be either penetrated with shafts, or stripped from the deposit entirely. In either case, before the placer can be mined, it must be thawed. At modern dredging operations, the frozen muck is stripped from the placer by powerful jets of water from hydraulic giants. The placer, and several feet of decomposed bed-rock, are then thawed by forcing water through narrow pipes which have been driven into the deposit. Other methods of thawing frozen placers were used extensively during the early years of the Klondike 'gold rush', but experimentation later proved that creek water at its natural summer temperature was a more effective and economical thawing medium than any other which had been used. EVOLUTION OF COLD WATER THAWING Early prospectors of the far north reached placers by digging shafts through the frozen muck. They then thawed the placer sand and gravel by building wood fires at the bottom of the shafts.

Jan 1, 1951

By Trent Hamilton

Cameco ? McArthur River Operation is a high-grade uranium mine in northern Saskatchewan. Average grades mined are nearly 20%, more than 20 times higher than other operating uranium mines in the world. The significant risks involved with mining this grade has been effectively mitigated using innovative and unique controls, implemented from development and production mining through to ore processing. The types and sources of radiation are presented and protection measures are discussed. McArthur River?s strong radiation culture is evidenced by continually low radiation exposures while transitioning to new mining zones.

Aug 1, 2010

By Z. Farhat

In spite of advances in cutting tool technology, the understanding of the basic wear behavior and failure mechanisms needs further study. Tool wear is the main factor contributing to geometrical error and thermal damage in machined components. Manifested as a reduction in tool life, it also affects the workpiece surface finish, increases cutting forces and induces residual stresses. Furthermore, the emergence of high and ultra-high speed machining processes necessitates the investigation of tool wear under these severe working conditions. Tungsten carbide-cobalt composite material has been used traditionally as wear resistant materials for many years. One main application of this material is in cutting tools. WC-Co tools consist of hard WC particles imbedded in a tough Co matrix, which functions as a binder phase. More recently, Cubic boron nitride (CBN) tool material have attracted special attention due to its high hardness and excellent wear resistance. Boron nitride in its cubic form is known to be the hardest material next only to diamond. In this paper microstructural and tribological properties of commercial grade WC-Co and CBN cutting tool materials are investigated under high speed cutting conditions. The CBN cutting tools were found to be superior to tungsten carbide (WC) tools. Four-fold increase in productivity and significant reduction in chipping and cratering was achieved for CBN as compared to WC. Wear mechanisms are proposed and are related to the observed wear characteristics in the cutting zone.

Jan 1, 2006

By Alan B. Morrow, William A. Poe

"Minerals processing operations are constantly challenged with improving production rates, yields, energy efficiency and process stability. Advanced Process Control has proven to be an effective tool for improving operations by capturing the full process capabilities consistently. However, the velocity of applying the technology as well as the sustainment of these significant benefits has been hampered by the usability of the software and adaptability of the applications.Some of the new technology developments that improve the usability and adaptability of advanced process control include:• modern and intuitive user interfaces,• customizable models to support unique process behavior,• fast and flexible OPC connection tools,• automated model building,• integration with first principles dynamic models and• improved performance monitoring.This paper will briefly discuss the new technology developments that have improved the usability and adaptability of advanced process control and how this can affect minerals processing operations.In today’s environment, Minerals Processing plant managers continuously face new challenges and requirements including:• higher energy efficiency,• increased run lengths,• reduced product quality variability,• reduced emissions,• higher availability, and• lower operating costsOperating a unit to meet these challenges in real time is not easy for operators and conventional process control systems. However, innovatively using existing technologies in Minerals Processing plants can improve operations on a minute by minute basis and reap significant benefits.Advanced Process Control (APC) can extract the maximum performance benefits from existing equipment while respecting plant operating constraints. Expensive capital projects to upgrade equipment are not always necessary. Advanced Process Control can deliver significant economic benefits by maintaining the plant at its most profitable point as conditions change."

Jan 1, 2016

"Since the publication of a literature review on this topic (McIvor and Finch. 1986), the author has been involved in more than thirty rod milling efficiency tests at seven different milling operations. There have also been several interesting additional articles on rod milling found in the literature. This update describes the most important findings from investigations carried out since the previous review, as well as developments in the techniques used to evaluate the grinding efficiency of rod mills.Rod Mill Power DrawA series of power draw versus charge level measurements were taken on the rod mills at Leg Mines Selbaie and Kidd Creek Mines Limited (McIvor. 1989). These revealed a significant (about 10070) loss in power draw with the installation of new liners, a common observation among rod mill operators. This loss in power draw depends on the liner design, particularly the average thickness and lifting face profile of the new liner. The theoretical power usage of both mills was approximately 5070 lower than that given by the Allis-Chalmers power draw formula (Rowland. 1982).The shape of the power draw versus charge level curve suggested an opportunity for reducing media consumption. By increasing mill speed, power draw could be maintained with a smaller mill load, most significantly for mills operating with high charge levels. Analysis of data from 62 installations confirmed this (McIvor, 1989). On average, a 10 percentage point increase in critical speed results in a 15070 in specific media consumption (Le. kg of steel consumed per kWh of energy consumed). Table 1 lists a number of relatively high speed rod milling installations. No negative effects on the drive train, liner life, or the tendency for rods to tangle have been reported. A reduced lifting angle of the new liner leading face (e.g. 45 versus 90 degrees from the mill perimeter) is recommended for higher speed rod mills (Leclerq, 1990)."

Jan 1, 1995

By S. S. Yuan, Q. Z. Zhu, J. F. Shao

"This paper aims at enriching a homogenization-based anisotropic damage model for hard rocks under complex loading. A new damage criterion is proposed to capture material strain softening. Within the framework of irreversible thermodynamics, we are particularly concerned with two strongly coupled dissipative mechanisms: frictional sliding and damage by microcracking, which usually take place at cracks within cohesive geomaterials under compression. Focusing on the representative elementary volume containing multiple crack families, the free enthalpy of the matrix-cracks system is obtained. Importantly, a back-stress term is involved in the local stress applied to microcracks. This back stress plays the hardening/softening role in the friction criterion which is formulated at local scale. Strain hardening owns to the accumulation of frictional shearing and dilatancy while strain softening is caused by crack growth. The multiscale damage model is used to simulate laboratory tests on the Westerly granite under true triaxial compressions. INTRODUCTIONWhen subjected to compressive loads, hard rocks present nonlinear mechanical behaviors and induced material anisotropies. In that process, two main dissipative mechanisms have been largely identified: damage by crack growth and frictional sliding along closed crack faces, which are usually strongly coupled to each other on crack scale. Theoretical investigations have shown that the damagefriction coupling analyses allow explaining a large number of experimental phenomena involved in brittle or quasi-brittle materials. Concerning constitutive modeling, the standard Eshelby’s solution-based homogenization procedure for heterogeneous materials was recently applied successfully to describing the mechanical and poromechanical behaviors of cracked frictional solids."

Jan 1, 2015

By R. Burnette

Gold has been mined from a variety of deposit types that range in age from Archaean to Recent. The large variability in the geological settings of the gold deposits implies transport and concentration of gold by magnetic, hydrothermal and sedimentary processes. The factors that control the concentration of gold at certain sites and the grade estimation thereof remain major topics of debate. Due to the complex nature of the Witwatersrand Basin a mineralogical study, including mineralogical, petrographic and geochemical investigation was launched on TauTona Mine in order to characterize the various reef facies. The aim of the investigation was to determine if a correlation could be found between macroscopic characteristics of the reef, hanging wall and footwall, and the microscopic nature of the ore (especially gold grade). Petrograpgic and mineralogical results indicate that a correlation exist between gold, detrital and hydrothermal sulphides, uraninite, carbon, detrital heavyminerals and phyllosilicates. No correlation exist between gold and Mg, Fe or S. It appears that clast supported reef is of higher wade than matrix supported, but more work is suggested. No correlation exists between reef thickness and grade. The reef samples had the lowest phyllosilicate content compared to the hanging wall and footwall samples with pyrophyllite the most dominant. All of the correlations diagrams showed significant scatter and suggests a multi- factorial mineralization model. Gold distribution is also controlled by sedimentary features and thus it is not possible to select a single model for the formation and distribution of gold. It is evident that both sedimentary and hydrothermal factors influenced the mineralization and gold distribution on TauTona mine. It is thus essential that all related theories be incorporated in the development of a grade prediction model.

Jan 1, 2011

By W. J. Weymark

"The Gregg River project is located 40 kilometres southwest of Hinton, Alberta, adjacent to and east of Jasper National Park. This metallurgical coal mine has been developed as a joint venture between Gregg River Coal Ltd. (a subsidiary company of Mana/ta Coal Ltd.) and seven Japanese companies. This 200-million dollar project consists of a conventional truckshovel open-pit operation and a coal preparation plant rated at 2.14 million tonnes of clean coal per year. Mining operations started in October 1982 with plant start-up following in April 1983. Introduction This paper is an overview and update of the Gregg River project, a metallurgical coal mine being developed as a joint venture between Gregg River Coal Ltd. (a subsidiary of Manalta Coal Ltd.) and seven Japanese companies. The Gregg River Coal leases cover 3440 hectares and are located 40 kilometres south of Hinton, Alberta, adjacent to and north of Cardinal River Coal Mine (Fig. 1). This 200-million dollar project consists of a conventional truck-shovel operation and a coal preparation plant rated at 2.14 million tonnes of clean coal per year. A total of 31.5 million tonnes of clean metallurgical coal will be sold to the Japanese over a fifteen-year term. At present, mining operations are ahead of schedule and the plant started up on schedule in April 1983. Access and Climate An all-weather road, Highway 40, connects the minesite with Hinton (the nearest commercial centre) and a Canadian National Railway (C.N.R.) spur line connects the minesite with the C.N.R. main line in Edson. Hinton is accessible by road chartered airline and rail. ' ~h~ rug~ed and varied topography in the area creates large vanations m temperature and precipitation over short distances. The region is characterized by precipitation throughout the year long cold winters and short cool summers. The mean temperatur~ of the area range from a low of -14°C in January, the coldest month, to a high of 12°C in July, the warmest month. Long-term precipitation data indicates a mean yearly precipitation of 870 mm of which 620Jo occurs during the summer months."

Jan 1, 1985

By T. G. Sitharam, Resmi Sebastian

"Wave propagation studies across jointed rocks have significance in the fields of rock mechanics and geophysics. The passage of a seismic wave induces strains in rocks and often, these strains are of low magnitudes except at the vicinity of source. These low magnitude strains are generally in the elastic range and hence elastic constants necessary for the design and analysis of strength of rock mass, can be derived from wave velocities. Measurement of travel time velocities and measurement of resonance frequencies are the two methods usually adopted for obtaining wave propagation velocities.Resonant column apparatus measures wave velocities from the resonant frequencies obtained during testing. Depending on the type vibration applied, torsional or flexural, shear and compression wave velocities are secured. By varying the amplitude of vibrations applied, various strain levels can be introduced and corresponding resonant frequencies and wave velocities can be calculated. The resonant column experiments were performed on a model material, hardened Plaster of Paris (POP) samples, in laboratory. The paper explains the preparation of samples and the working mechanism of resonant column apparatus along with the estimation of wave velocity from resonant frequency. The numerical simulation of resonant column apparatus using distinct element method and its validation with the experimental results are presented in the paper.A distinct element code is usually used to simulate the movement of materials with intersecting discontinuities. Finite rotations and displacements of individual blocks representing the material are permitted and new contacts between the blocks are identified as the calculation progresses. Three dimensional Distinct Element Code (3DEC), the software intended for the numerical simulation of rock engineering projects, can well simulate the behavior of jointed rocks under static and dynamic loading conditions. The numerical simulation of resonant column apparatus has been performed with 3DEC considering its efficiency in modeling jointed rocks.The numerical modeling of the resonant column apparatus with application of torsional and flexural vibrations to the sample is elaborated in the paper. The response of samples to a range of frequencies is obtained and the frequency that induces maximum displacement in the sample is measured as the resonant frequency, for any particular strain level. The displacements measured at various points of the sample during application of vibrations are compared and presented. The numerical modeling of resonant column apparatus with an intact sample (without joint) and a sample with a joint incorporated are explained at a particular strain level. The resonant frequencies obtained from laboratory experiments and numerical simulations are compared and illustrated. It has been found that resonant frequencies obtained using numerical and laboratory experiments are in good comparison and can be extended for various strain levels and sample conditions."

Jan 1, 2015

By C. G. Anderson

Industrially proven and applied nitrogen species catalyzed (i.e. NSC) acidic pressure leaching has been utilized to treat a number of ores, concentrates and recycled materials. This versatile technology offers many advantages including low temperatures, low pressures, low capital costs, low operating costs, faster throughput and less costly materials of construction than conventional pressure oxidation. This paper will elucidate the application of this technology for production of gold, silver, palladium, rhodium, zinc, germanium, gallium, cobalt, copper and nickel. Recycled material applications will also be elucidated. In addition, details of an application for treatment of a refractory chalcopyrite copper and gold bearing ore will be presented and pertinent economics discussed.

Jan 1, 2004

By M. A. Marois

This paper proposes an improved temporal stability condition for the implementation of an inverse heat transfer method for predicting the time-varying bank thickness of the phase change protective bank inside a high temperature furnace. The direct problem is handled with the enthalpy method. The inverse method rests on the Adjoint Problem and the Conjugate Gradient Method. It is shown that the temporal stability condition for the inverse phase change problem relies on the time delay of the temperature measurements. Results indicate that this time delay is proportional to the heat diffusion time including heat diffusion through the mushy zone.

Jan 1, 2011

By Jose A. Jimenez

"Mining operations generate an enormous amount of data that is difficult to organize, analyze and act on. These data require an extremely broad range of experts to investigate and manage the cross-disciplinary information. The data collects in paper files, diverse databases, historians, stand-alone applications, and excel files. This collection of sources represents everything from monthly, weekly, or daily inputs to real-time feeds or sporadic unscheduled entries. With the operational complexities ever increasing and fewer engineers per mine, an efficient operation is becoming more and more challenging. Engineers are typically burdened with data collection, clean up, and administrative efforts leaving very limited time for engineering assessment and/or optimization analysis. Often optimization becomes limited to the analysis of equipment uptime through existing field automation systems. A great portion of the field data is tucked away in historians seldom reaching those engineers who might leverage the data. Few mine operators have the time or budget to re-architect their operations data collection or management practice, so solutions must enable improvements without requiring expensive or time-consuming implementation. This presentation highlights examples where the aforementioned challenges are addressed using a solution framework designed to enable: 1) data integration and connectivity, 2) monitoring and opportunity recognition, and 3) engineering workflow automation. The initiative extends the concepts and success proven in the automation market segment to all disciplines across the mine operations. INTRODUCTIONThe mining industry by its very nature spends a great deal of its capital on equipment maintenance and replacement. In addition, periodic shutdowns due to equipment failure are typically very costly in terms of interrupted operations. Keeping mining equipment running at peak performance and avoiding costly shutdowns can make a huge difference in the overall return from mining operations. Today, information can be make available that can go a long way towards spotting equipment issues and permitting timely intervention to avoid costly unplanned shutdowns. That said, gathering all of the information from numerous points on many different pieces of equipment necessary to enhance overall equipment effectiveness presents its own daunting issues."

Jan 1, 2016

By Vic Briccardi

Energy Management Challenges The Holistic Standard to Energy Management Energy Management Information System (EMIS) "Best Practices?: Energy Management Maturity Curve De Beers Canada Profile & Mine Locations Significant ROI Driven by Real-Time Energy Visibility Mining Energy KPI?s Summary: What Does EMIS Deliver? Q&A Session

May 1, 2013

By D. G. Eskin

"It is well known that it takes some time for the solid phase to completely dissolve upon melting, especially inside the defects of insoluble particles, e.g. oxides. Until then the oxides remain active solidification substrates in the case of subsequent solidification. It is also known that ultrasonic melt treatment causes grain refinement through activation and dispersion of solidification substrates (one of the mechanisms) and also accelerates the dissolution of solid metal in the melt. In this study we combine these effects and demonstrate that the introduction of an alloy rod into the matrix melt of the same composition results in significant grain refinement, this effect being increased by the ultrasonic vibration of the rod. The achieved grain size is comparable to that obtained by a standard Al–Ti–B grain refiner. All samples were cast using a standard TP-1 mould to enable correct comparison. The effect of the temperature range of the rod introduction, as well as the effect of ultrasonic vibrations are discussed.INTRODUCTION The fact that by introducing solid metal into the melt one can achieve structure refinement is rather well known. As early as in the 1930s–1950s a series of papers and patents have been published, showing the benefits for grain refinement when dissolving solid metal in the melt before solidification (Danilov and Neimark, 1938; Scheil, 1956). Later on this way of structure refinement was developed further and dubbed “suspension casting” or introduction of “internal chills” (Madyanov, 1969; Zatulovsky, 1981). The solid metal was added in a form of cut wire, cut sheet, or powder, with the resulting grain refining, elimination of columnar grain structure in ingots and castings of steel, copper and aluminium alloys. The underlying mechanisms have been suggested as (1) rapid cooling of the melt due to the latent heat consumption upon melting of the solid metal with the resultant melt undercooling and (2) introduction of many solidification substrates in the form of crystal fragments and active non-metallic inclusions (Danilov & Neimark, 1938; Balandin, 1973). A number of patents have been filed where either the same solid alloy or a master alloy with additions (e.g. Ti for Al alloy) is introduced in the amounts up to 50% (typically less than 10%) into the melt close to the liquidus temperature (Schmidt, 1966; Talbot & Soller, 1973, Krupp, 1974; Bondarev, 1979). The main reason that this technique is not widely used in industry is the possible incomplete dissolution of the solid parts introduced into the melt with ensuing inhomogeneous as-cast structure and potential defects. Also the selection of the temperature range where the technology works the best is not clear."

Jan 1, 2018

By Simon C. Dominy, Ian M. Platten

"Abstract - Gold-bearing quartz reefs commonly show extremely erratic and unpredictable grade variation, although gross geological continuity may be good. This type of variation is often described as being nuggety or having a high nugget effect and can be measured quantitatively using the semivariogram. Understanding of geological features such as reef texture and structure will provide improved models for the interpretation of assay data, drill core descriptions, etc. In this paper, a case study from the quartz-hosted gold occurrences in the Gwynfynydd mine, United Kingdom, is described. The work provides a starting point for models of lateral variation and demonstrates the types of structural and textural features that may be sought to give clues to the prediction of gold distribution in similar deposits. Gold deposition at Gwynfynydd is primarily associated with the reef footwall. The host veins form a discrete group of structures that may have been emplaced early in the sequence of quartz veins forming the reef. This potentially exposes them to a maximum number of dissection events during repeat dilations of the lode. Gold was deposited in the local porosity at extreme concentrations, equivalent to kg/t grades, when the host fissure had become filled with a porous framework of crystalline quartz and sulfides. Distribution of porosity varied laterally along the vein as the result of the formation of clump-like growths of minerals from the vein walls. The growth style is relevant to the distribution of gold although it may not be relevant to the occurrence of gold in a particular vein. The preservation of pores with some connectivity late in the vein fill sequence may be important in permitting continued but slow fluid flows. This facilitates effective fluid reaction with wall rock-derived methane, thus changing the relative rates of gold and quartz deposition in favor of gold. The textural studies explain the first-order control of nugget distribution at Gwynfynydd but do not allow for prediction and optimization of the resource estimation process. This is principally because of the very low geological continuity and poor predictability of the high-grade pockets. Nonetheless, the work does provide a clear geological explanation for the erratic nature of the gold. It indicates textures and structures that can be used to determine geological continuity of the goldbearing elements within the gross reef envelope."

Jan 1, 2001

By K. Hanumantha Rao, A. Javadi

Our recent studies revealed that the sulfide minerals in contact with water during grinding produced hydrogen peroxide (H2O2) where the amount of H2O2 production by the minerals found to be in the order of pyrite > chalcopyrite > sphalerite > galena. The H2O2 effect on the oxidation of pulp components and its influence on the concentrate grade and recovery in flotation have been studied and the results have been presented and discussed in this paper. Studies have also been carried out to build correlation between percentage of pyrite in the concentrate, grinding conditions and concentration of OH•/H2O2 in the pulp and as well of controlling the formation of these species through known chemical means for depressing the generation of the oxidant. Flotation tests using a complex sulfide ore with the same reagent scheme that is being used at Boliden concentrator in Sweden but with the addition of i) collector and depressant, ii) Na2S reductant and iii) inorganic (EDTA) and organic (TETA) surface modifiers, during grinding stage have been performed to judge the beneficial or detrimental role of H2O2 on the selective flotation of sulfides. The results demonstrate that the selectivity of metal sulfides against pyrite increases with increasing generation of H2O2 in the pulp liquid. H2O2 is also found to be a better oxidant in chalcopyrite-galena flotation separation than the commonly used K2Cr2O7.

Jan 1, 2016

By J. Beddoes

Many high strength aerospace alloys undergo solution heat treatment (SHT) and aging to develop precipitate strengthening. Most simply, SHT involves an isothermal hold in a single phase region followed by relatively rapid cooling to develop a super-saturated solid solution from which precipitates form during aging. However, subsequent properties are sensitively dependent on the details of the SHT, which frequently also serves a homogenization function. Altering the details of the thermal cycle during SHT significantly improves the properties attained during aging, as presented by examples of SHT design for titanium aluminide intermetallics, polycrystalline and single crystal superalloys, and 7075 aluminum.

Jan 1, 2010