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By A. N. Kumar

Two fabrication stages in the manufacture of pipelines are identified as causing significant deterioration of the steel plates, namely cold bending and welding. The objectives of this work include quantitative assessment of the degradation of the quality of the steel plate by the loss of fracture toughness, and an estimation of the safe working pressure. The study was conducted on three API grade steels: X42, X46 and X60. After cold bending by the UO technique, various welding technique were employed for joining of the bend plates along the pipe length. A crack-tip opening displacement parameter (CTOD) was used at the onset of initiation and at the first load maxima as the criterion for assessing the toughness degradation under various fabrication stages and regime (such as WZ, HAZ and parent body). In addition, strength, hardness and impact energy values were determined to check the degree of degradation. Microstructural and microfractographic investigation of the fractured samples were also carried out in the scanning electron microscope (SEM). X60 grade steel plate suffers from CTOD toughness loss by around 38 and 55% after welding and cold bending, respectively, for the conditions studied. A combined effect of the two stages results in a loss in toughness by around 70% for the same steel. In X42 grade, the loss in impact energy ranges from 78 to 35 J due to electrical-resistance welding study (ERW). Crack resistance curves are also obtained for the steels to study the crack growth resistance behaviour and to supplement the information on crack initiation behaviour. The orientation of the pearlite banding, as observed on the fracture plane with respect to notch front and applied loading direction appears to have a strong influence on the microvoid-coalescence mechanism of fracture as well as the toughness values. An integrated analysis of the performance of pipelines, considering all these key factors, is discussed.

Jan 1, 2005

By P. E. Cavanagh

Abstract Many investigators have been interested in developing some non-destructive method for detecting or determining the changes in physical properties in steel occurring during endurance tests or normal service life of a part which fails in fatigue. This paper presents a broad discussion of some of this work and the possibilities of developing useful test procedures based on some of the information obtained in the past. Changes in magnetic properties, electrical resistance, damping capacity, X-ray diffraction patterns, and remaining fatigue life at load different from service load have all been investigated as possible means for following the sequence of events during fatigue failure. In some special instances, tests such as these may be used to predict fatigue failure. As an in stance of practical application of the continuous determination of changes in magnetic properties during fatigue, a brief account is given of work done in non-destructive inspection of mine hoist-rope. As a result of extensive experiments and field crisis, it has been found possible to detect the beginnings of failure in a wire rope in service. The test method used will detect plastic deformation in a wire rope, no matter what its cause. There is no possibility of determining the remaining useful life of a rope by calibrating changes in magnetic properties in terms of remaining fatigue life. A change in magnetic properties at a point in a rope may indicate a decrease or increase in fatigue life, depending on the overload history of the rope. A continuing change in magnetic properties ac a point, however, does reliably indicate a developing weak point which will eventually lead to failure. The important point about any change in magnetic properties is not the magnitude of the change, but whether or not it continues.

Jan 1, 1947

By J. A. Brusset

THE Greenhill mine of West Canadian Collieries, Limited, is situated at Blairmore, Alberta, and produces 2,500 tons per day of bituminous coal. On Monday, October 25th, 1943, smoke was discovered by a party of firebosses on their regular weekly inspection of air-ways. Probably the fire had been smouldering for several days but, as it had started on the outcrop at the top of an old raise filled with dirt, only a small quantity of smoke could filter through, and the plume of mist that crowns the fan at that season had prevented the fan-man from noticing it. This raise is only about 200 feet from the fan, and is 70 feet long between the fan-drift and the outcrop. It was impossible to prove the origin of the fire, as it had probably started several days before it was discovered, but it is possible that a careless smoker may have thrown a match into the opening at the outcrop, and that the old, dry timber had caught fire. The airways are in No. 2 seam, a bituminous seam 18 to 25 feet thick surmounted by shales and sandstones. Only 45 feet vertically above it is No. 1 seam, 12 feet thick, overlain by a strong conglomerate. In that vicinity, No. 1 seam had been worked out about ten years ago and the strata between the two seams are undoubtedly fissured. The pitch of both seams is 43 degrees.

Jan 1, 1945

By S. Nakamura, K. Fujiwara, S. Hirosawa, S. Tsukamoto, Y. Koshino, Y. Aruga

"In this study, hardness test, differential scanning calorimetry(DSC)and transmission electron micros copy were carried out to investigate the age-hardening behavior of Al-Mg-Si alloy with a Mg+Si concentration of 1.5mass%, and a Mg/Si ratio of 1.0. Pre-aging treatment was conducted for the solution-treated and then water-quenched specimen at 100, 80, 60, 40, 20 (natural aging), 0 and -20°C for 20min or 5h, followed by artificial aging at 170°C for 20min. It was found that when pre-aging time is prolonged from 20min to 5h, the bake-hardening response is deteriorated irrespective of the pre-aging temperature. In particular, the specimens subjected to pre-aging at 20-40°C for 5 h hardly increased the hardness with the subsequent artificial aging. From the results of DSC measurement, it was suggested that as pre-aging temperature is lowered, the amount of solute clusters formed during pre-aging, i.e. Mg-Si clusters and Si-rich clusters, is decreased, but the ratio of Si-rich clusters is increased, resulting in the deteriorated bake-hardening response.INTRODUCTIONIn recent years, Al-Mg-Si alloys have been widely used forautomotive body panels due to their excellent characteristics such as high strength-to-weight ratio and good formability. Their strength is increased not only by artificial aging during paint-bake treatment; i.e. “bake-hardening”, but also when kept at room temperature(RT);i.e. “natural aging”, in association with the suppressed bake-hardening response. Such a “negative effect of two-step aging” has been a serious problem because Al-Mg-Si alloy coils are unavoidably maintained at RT in the manufacturing process of body panels; e.g. shipping and storage. However, it was reported that pre-aging above 70°C before the two-step aging can restore the bake-hardening response, and such an improvement is related to the formation of solute clusters(Sato, 2006; Abidet al., 2010; Takaki et al., 2014; Zandbergen et al., 2015). From the comprehensive analysis by three-dimensional atom probe (Aruga et al., 2014 and 2015), it is believed that Mg-Si clusters formed during pre-aging transform into the strengtheningß"" phase, whereas Si-rich clusters formed during pre-aging act as a detrimental precursor of ß""phase. In this study, it was aimed to investigate the effect of pre-aging conditions, especially pre-aging temperature and time, on the formation of solute clusters during pre-aging, in order to elucidate the mechanism of the age-hardening behavior of an Al-Mg-Si alloy."

Jan 1, 2018

By H. Sano

Most of the dust generated from the copper smelting process in Chile has been stored after the stabilization by hydrometallurgical process because it contains high concentrations of arsenic. However, in recent years, the dust generation has increased because of degrading the quality of concentrate. In addition, the environmental regulations become stricter. On the other hand, valuable metals such as copper and zinc are contained in the dust at high concentrations and it is desirable to recover them. In this study, the effect of dust recirculation to the smelting process was examined in order not only to decrease the amount of dust but also to recover copper. Dust generation and the distribution of arsenic, lead, zinc etc. among the matte, slag and gas phases were evaluated as a function of the amount of recirculated dust, partial pressure of oxygen and temperature. It was found that the direct dust return to the smelting process was quite effective for the recovery of copper and the reduction of dust generation, but the acceptable dust amount was limited by the produced matte quality.

Jan 1, 2007

By R. H. McMillan

A classification of important uranium deposits which utilizes both genetic and descriptive criteria is presented. The dual aspect is useful because, while the non-genetic nomenclature for the different deposit types is amenable to various interpretations, the critical characteristics of each deposit type can be analyzed to clarify various genetic points. Although the classification is intended primarily for Canadian uranium deposits, most of the important deposit types known elsewhere can be accommodated.

Jan 1, 1978

By M. Medraj, M. A. Arafin, D. P. Turner, P. Bocher

In this study, the kinetics of isothermal solidification during TLP bonding of Inconel 625 and 718 superalloys with nickel based multi-component filler alloy BNi-2 have been studied through a combination of direct experimentation and mathematical modeling in order to determine the effect of process variables and, thus, to optimize the process. The predicted isothermal solidification completion times from the boron diffusion model and migrating solid/liquid interface model were in good agreement with the experimentally determined values and, they were found to be significantly less than those of other nickel superalloys with different nickel based filler alloys. Further, significant reduction of holding time was observed with increasing bonding temperature and with decreasing joint gap. No significant grain growth in the base metals has been observed in the temperature range being investigated (1325 - 1394K).

Jan 1, 2006

By The Staff

"THE property of Red Mountain Mines Limited is located 11/2 miles north and west of the town of Rossland, in southern British Columbia. The mine is situated on the flank of Red mountain, famous in pioneer days as the site of a number of profitable gold-copper producers. Mining and milling commenced in May, 1966, and by the first of July the concentrator was treating close to its average design capacity of 400 tons per day. The following description of the property and its operations is divided into three parts, dealing respectively with geology, mining and milling.GeologyAll the known ore reserves of Red Mountain Mines occur on the Coxey claim, on the west slope of Red mountain. Although there are indications of molybdenite mineralization elsewhere on the Company's property, these have not been developed.The Coxey and adjoining areas are underlain by the Mount Roberts formation of the Rossland volca-nics. This formation consists of an interbedded series of volcanic and sedimentary rocks, mostly brecciated and silicified near the ore zone, and all intruded by igneous rocks which occur in various forms, and vary in composition from basic to acid. The country rock in the vicinity of the mineralization seems to be mostly a volcanic, approximately andesitic in composition, and possibly a surface flow. There is much banding, some of which is undoubtedly due to tuff and agglomerate layers, and some to narrow, siliceous, sedimentary horizons such as the surface exposure of the main ""A"" orebody, much of which was a thin capping of greyish banded rock that looked like quartzite. The drill holes also intersected occasional layers of black, argillaceous quartzite, sometimes altered to a greenish colour. The whole assemblage has been silicified with varied intensity, sometimes to such an extent as to have obscured or obliterated the original characteristics. The mineralized zone has also been strongly brecciated, the fragments varying in size from less than an inch up to large masses, best described as a mega-breccia. Anomalous results obtained in drilling, such as sedimentary sections that do not appear in adjoining holes, may sometimes be due to the presence of these large blocks, no longer in their original position. The whole volcanic unit is thus very complex and confusing. For practical purposes, the ore may be said to occur in a greenstone formation with minor sedimentary interbeds and considerable later igneous material."

Jan 1, 1967

By Shuai-Jun Li, Xia-Ting Feng, Xian-Jie Hao

"The anisotropy of rock is of great importance to the rock engineering. To investigate the anisotropic character of slate, the rock samples of slate under different confining pressures and bedding plane angles was conducted on the MTS. The results indicated that the relationship between bedding plane angle and elasticity modulus, friction angle, cohesion and strength was shown as U pattern. The minimum value of them is located from 30°to 45°.In addition, the elasticity modulus and Poisson's ratio increase with the increasing confining pressure. The slate behaves brittle failure both in the uniaxial and triaxial compression. The failure pattern of uniaxial compression is generally tension failure, and triaxial test usually shows shear failure. The failure angle decrease with the increasing of confining pressure.INTRODUCTIONThe anisotropy of rock is that loading in different orientations the rock has different mechanical properties. The anisotropic property of rock is always an important problem in rock engineering (Hoek E. & Brown E. T., 1980). J. C. Jaeger (1960) first presented that transverse strength criterion for sliding fracture on joint surface. Later he revised rock parameters to anisotropy empirically for isotropic Mohr- Coulomb criterion. His main idea is revising cohesion according to loading direction (J. C. Jaeger, 1971). Then, many scholars study a lot on transverse strength criterion. E. Z. Lajtai (1969) considered the influence of connecting rate in all directions in joint groups for shear strength in intact rock; R. Mclamore and K. E. Gray (1967) referenced the theory of J. C. Jaeger. They not only revised cohesion also revised friction coefficient. Y. M. Tien (2000, 2001) made further study on the influence of connecting rate in joint group to transverse strength. R. Nova (1980) studied on the variation of strength when rock specimens in triaxial pressure and complex stress paths. O. Cazacu(1998) put forwards a new anisotropic strength criterion for analyzing rock strength. S. Pietruszczak(2000) introduced fabric tensor for characterizing inner seismic structure and he built an anisotropic strength criterion containing the invariants of stress tensor and seismic fabric tensor."

Jan 1, 2015

By Trang T. Tran-Valade

With continually increasing energy prices, the mining industry has been on the search for new energy optimization technologies. One area that is garnering great interest is Ventilation-On-Demand (VOD). Prior to selection and implementation of a VOD solution, it is important to fully understand the mine requirements as well as its existing infrastructure and the interaction with other automation in place at the site. With this information, a business case can be generated including a cost versus benefit comparison for various control strategies. To assist in the development of the business case, this paper will identify key areas for consideration and recommendations for an implementation plan.

May 1, 2013

By J. Font

The RAF or copper fire refining process at the Caletones smelter of CodelcoChile consists of several pyrorefining stages that successively lowers the levels of S, Fe, Pb, As, Sb, Te, Se and to some extent 0 in the copper melt, allowing the production of high quality fire-refined copper of 99.93 % purity (RAF copper). This chemical feature of the RAF copper is only achieved by quite long processing times, and a considerable consumption of fluxes and fuels in the RAF vessels. The main goal of this study was to improve the RAF process performance by thermodynamic considerations and industrial scale tests, i.e., an in situ approach for the process as featured by intensive sampling, characterization and subsequent modifications. Thus, both theoretical and industrial data were derived, and based on kinetic and thermodynamic evaluations, a higher operational standard was achieved for the RAF process. These new operational practices allowed enhancing the overall economic of the RAF process, by reducing the time and operational costs, and consequently increasing the availability of the vessels.

Jan 1, 2007

By Ram Song, Yohei Harada, Shinji Kumai, Kazuho Otsuka

"Recently, vertical-type high-speed twin-roll casting (HSTRC) has been developed. The HSTRC shows extremely high cooling rates over 1,000 K/s even at the mid-thickness area. The fabricated strip has many metallurgical characteristics; super-saturation of alloying elements, fine solidified structure, and homogeneous distribution of fine constituent particles. In Al-Mn based alloys, the Mn alloying element can be supersaturated in the a-Al matrix and also form Mn-containing constituent particles during solidification. The Mn supersaturation and the distribution of primary/secondary particles in cast products affect the metallurgical behavior in the down-stream processing and can improve mechanical properties of the final products. In this study, Al-Mn based alloy strips were fabricated by HSTRC with various Mn contents. The solidified microstructure, constituent particles and its distribution, and Mn solubility were investigated in the as-cast condition. Due to the high cooling rate of HSTRC, fine constituent particles were homogeneously distributed, and coarse intermetallics were not observed. Mn solid solubility was estimated by electrical conductivity. The estimated Mn solubility was equivalent between strip surface and mid-thickness area.INTRODUCTION Al-Mn based alloys, as non-heat treatable wrought aluminum alloys, are widely used in packaging and heat exchanger for automobile industry. Besides Mn, Al-Mn based alloys often contain Fe and/or Si as alloying elements or natural impurities. During solidification, Mn can be super-saturated in the Al matrix, and also form Mn-containing constituent particles. Additionally, in the subsequent thermal-mechanical processes such as homogenization, rolling, and intermediate annealing, Mn in solid solution precipitates out of the Al matrix as secondary particles. The size, distribution, type, and the amount of dispersoids including constituent particles affect to texture evolution, recrystallization behavior, and final mechanical properties of wrought Al-Mn based alloys (Huang et al., 2016; Huang & Marthinsen, 2015; Engler et al., 1995; Muggerud et al., 2013). Therefore, controlling the initial level of Mn super-saturation and the distribution of constituent particles are important in the cast Al-Mn based alloys."

Jan 1, 2018

By M. Savich

A graphical method has been developed for the evaluation of the U.S. Occupational Safety and Health Act Noise Exposure Index and the Equivalent Continuous Sound Level. The method makes use of a noise survey form and a mechanical integrator with two sliders, and is less tedious and susceptible to error than alternative methods. The graphical method is adaptable to various codes for noise exposure and may be used with any instrument that measures noise level. One example of its application to a practical situation in a Canadian mine is given to demonstrate the procedure .

Jan 1, 1978

By G. A. Vissac

In this paper we intend to deal particularly with the economic side of coal washing as it applies to our mines. We will then discuss why the dry-cleaning process has been selected, and give a brief description of our plant, dwelling only on its specific features and referring the reader to the numerous papers published on the subject for any details on the principles and machinery used in dry cleaning. ECONOMIC DISCUSSION The washery introduces an extra cost for depreciation, operation, and loss in treatment. A certain proportion of the coal, now being sold, and which the miners have been paid for. will have to be wasted. As a whole, the total increase in cost would be approximately 60 cents per ton. On the possibility of recovering this amount depends the success of the washery. There are two advantages to be expected from the washery, the first, which occurs at the mine and which will be certain; the second, more difficult to estimate, because it depends upon convincing our customers that they should pay more for a better product.

Jan 1, 1924

By R. W. Lawrence, O. Lopez

Many gold deposits in the world have not been developed clue to the presence of copper and other base metals which can cause metallurgical and environmental challenges clue to the formation of base metal cyanide complexes. SART technology (sulphidization-acidification-recycle-thickening) can resolve these issues by recovering copper as a high grade sulphide concentrate, recycling the associated cyanide back to the gold leach, and eliminating the downstream environmental liabilities. Project economics can be improved substantially, leading to a positive re-evaluation of new and existing gold-copper projects. Some aspects of the design and operation of two recently commissioned SART plants will be discussed.

Jan 1, 2011

By L. Li

ABSTRACT Stope backfilling is a common operation in many underground mines, which requires a barricade at the base of the stope near the drift entrance to retain the backfill in place. In this paper, the distribution of pore-water pressure in barricades made of waste rock is analyzed. An analytical solution is introduced and applied to estimate the pore-water pressure along the base and full height of the barricade. Results show that the analytical solution generally accurately predicts the distribution of pore-water pressure obtained from the numerical calculations, especially in the upstream part of the barricade, where it is most critical.

Jan 1, 2013

By H. A. Kramer

The Flin Flon mine is at present hoisting 5,000 tons of ore daily. In 1943, a peak production of 6,188 tons daily was maintained. Before discussing secondary blasting, it is felt that a short review of stoping procedure will be of value. A list of papers dealing with various phases of the mining operation is appended. Stoping Practice Stopes vary in width from 30 to 150 feet, in length from 200 to 450 feet, and in height from 200 to 500 feet. A typical stope would be 300 feet long, 300 feet high, and 90 feet wide. The dip of the orebodies varies from 60° to vertical, with an average of 82°. The ore is heavy, having a specific gravity of 4. Both sub-level benching and radial drilling are practised. Blast-hole diamond drills are responsible for 85 per cent of the total production. Two sizes of hole are drilled at present, 11 7 6 -inch and 1%-inch. For bench drilling, the burden on the 1 7/16-inch hole is six feet, with holes on 8-foot staggered centres; in radial drilling, the burden is six feet, with nine feet between the toes. The burden on the l 5/8-inch hole is eight feet with holes on 11-foot centres, or 13 feet on the toe of fanned holes. Holes are blasted with two No. 8 instantaneous electric caps per hole, using 403 Polar Forcite. A powder charge of 0.15 pounds per ton is used, with a tonnage factor of 5 and 6.4 per foot drilled for the two sizes. Two rows of holes are blasted together. Fragmentation is satisfactory with the above drilling pattern and powder charge. However, some overbreak and fall-off locally results in oversize material. It is estimated that, after primary breaking, 75 per cent of the ore will pass through the grizzly openings and 15 per cent will pass the draw points, leaving 10 per cent that must be broken further to pass the draw points.

Jan 1, 1946

By S. Mostaghel, Fariba Azgomi, Steven Goodman, M. Oliazadeh

"It is known that copper loss to the slag phase can be in the forms of chemical dissolution and mechanical entrainment. The contribution of each mechanism to the total Cu-loss depends on different parameters and may vary significantly. To reduce emissions to the atmosphere and to shorten the converting cycle, most industrial processes are aiming at production of high matte grades. Increased oxygen-to-sulfur potential, required by these processes, results in a highly oxidized slag, which in turn leads to an increased concentration of the chemically dissolved copper in the slag phase. Hence, slag cleaning processes are becoming increasingly important for economic viability of the smelting operations. Hydrometallurgical, pyrometallurgical, and mineral processing routes have been used for copper recovery from slag. The current article reviews a trade-off study evaluating two of the commonly used methods (namely flotation and electric slag cleaning furnace) by comparing the technical pros and cons, operability/maintenance requirements, and capital/operating costs of the operations.INTRODUCTIONLarge volumes of smelter and converter slags are produced by copper smelters around the world. It is estimated that for production of each ton of metal 2.2 tons of slag is produced (Gorai, Jana, & Premchand, 2003). Considering the current pressure on the mining and metals industry for “zero-waste, sustainable and environmentally friendly” extraction of metals, it is absolutely essential for metal producers to improve their efficiencies in order to remain competitive. To meet these objectives, almost all metal producers, from steelmaking plants, ferroalloys, base and precious metals producers, are trying to reduce their metal losses to the slag phase. In particular, copper producers are aiming to produce higher matte grades in their smelting furnaces to reduce the converting time and improve their overall throughput. Copper smelters need to minimize their copper/precious metal losses to the slag phase before final landfilling/use of slag. The current article, therefore, briefly reviews the copper loss to the slag phase, methods of metal recovery from the slag and then presents a trade-off study conducted for a green field flash smelter of the sulfide concentrates. A comparison was made between two of the major process routes for metal recovery from slag, namely slag cleaning furnace and flotation."

Jan 1, 2016

By Chuan-liu Wang

The bionic non-smooth surface has the characteristics of anti-wear, and reducing resistance. Based on bionic non-smooth surface?s characteristics, a bionic drill bit was developed. When the bionic drill bit is used, a bionic non-smooth surface forms on the crown of bionic drill bit. This surface can be used to extend the life of drill bit and improve drill efficiency. The bionic unit diameter and arrangement were researched in this paper to determine the optimal bionic non-smooth surface for further improving the life and efficiency of drill bit. Four bionic samples having the same structure size, materials and arrangement were designed and manufactured. After being sintered, the abrasion ratios of the four bionic samples were tested, and the results show that the abrasion ratio of Nos. 3 and 2 were similar (only 2% difference) and higher than that of No. 1 and 4. Therefore, the optimal diameter of bionic unit is 1.5 and 2.0 mm. Small diameter bionic drill bits were designed and manufactured, and tested in the laboratory. The results show that not all bionic structure bodies are better than normal diamond bits, except the bionic unit arranged in a reasonable range. When the angle was 24° and 30°, the arrangement of bionic unit were more reasonable, which shows the superiority of the bionic coupling bit.

Aug 1, 2013

By A. Haldar

This study focuses on the flow characteristics of hypereutectic Al-Si alloys in thin sections. The pattern assembly consisted of spiral horizontal patterns, 6.25 mm (0.25 inch) and 12.50 mm (0.50 inch) in thickness with a common sprue. Al-Si alloys with silicon levels of 14%, 18% and 22% were poured with superheats of 60°C, 115°C and 170°C. It was observed that metal fluidity (in terms of flow length and metal velocity) increased with increase in silicon levels and superheat for both section thicknesses. It was also observed that, for a section thickness of 6.25 mm (0.25 inch), silicon level had more pronounced effect on the metal fluidity. For 12.50 mm (0.50 inch) thickness, both silicon level and superheat affected the metal fluidity. The surface hardness of the castings increased with an increase in silicon level of the alloys at the gate and the flow tip. Detailed study of the flow tip was also carried out with a view to understanding the effect of silicon level and superheat on undulated flow length, surface hardness and microstructure.

Jan 1, 2007