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By W. J. Witte, M. K. Witte

"INTRODUCTION A pilot heap leach project was conducted on the B. P. Selco Hope Brook ore located in southwestern Newfoundland. The pilot heap leach was undertaken to assess and confirm the following:1) To confirm that heap leach technology now currently used in the United States could be applicable to Canadian sites.2) To confirm gold recovery by the Heap Leach technology3) To assess and study potential heap leach environmental concerns in cold and wet climate.PROJECT LOCATIONThe Hope Brook Project is located near the southern coast of the island of Newfoundland, approximately 100 kilometers southeast from Stephenville, approximately 25 kilometers west of Burgeo, Newfoundland. Access to the property is limited to helicopter, float plane or by sea through Couteau Bay. The property was covered with muskeg and very few trees. Surface relief was moderate with many poorly drained boggy sections confined to small areas. Many small unnamed lakes were located on the property which provided water to small brooks and streams flowing to Couteau Bay.Several locations were reviewed for the installation of the pilot heap leach facility. Important parameters used to select a suitable location included sufficient land area, close proximity to but not on the ore body, reasonable protection from wind, sufficient supply of fresh water, close to a suitable location for a portable crushing plant, reasonable access to aggregate material for preparation of the test pad and ponds and suitable contours to minimize site preparation."

Jan 1, 1987

By Robert B. Parsons

"Finance Minister Paul Martin's first budget disappointed almost everyone. The business sector was disappointed at the some what feeble attempt to grapple with the country's deficit. The mining industry was disappointed by tax proposals regarding mine reclamation that fall short of the industry's needs. Has anybody been happy with a federal budget? Federal Budget DisappointsThe federal government's budget papers that were tabled on February 22, 1994, contained a rather bizarre mixture of unrelated tax proposals. The budget signals an unexpected attack on the tax treatment of debt settlements, on certain types of corporate reorgani2ations, and on income earned by foreign affiliates. This is an old style budget, which proposes a pot pourri of technical changes and policy initiatives. Mine ReclamationEffective February 23, 1994, a taxpayer's contributions to a prescribed mine reclamation trust fund will be deductible as a current expense. The budget papers do not provide a definition of what will constitute a ""prescribed"" trust: this definition will surface in due course. However, the budget papers indicate that:• income earned in such trusts will be subject to tax each year;• all withdrawals from the trust (including income already taxed) will be included in computing the income for tax purposes of the recipient;• reclamation costs will continue to be fully deductible at the time incurred; and • contributions, trust earnings, and withdrawals will not be taken into account for the purposes of determining a taxpayer's resource allowance."

Jan 1, 1994

By Juliana Parreira

The past decade shows record increases in global demand for minerals and metals with an accompanying significant decline in skilled personnel. Mining companies today are examining new technologies to maximize production, reduce costs, and create safer work conditions to deal with this shortfall. Automation of an open-pit mine haulage system is receiving attention as a beneficial option since it provides more consistent and efficient operation of mining equipment, it removes workers from potential danger, it reduces fuel consumption significantly reducing greenhouse gas (GHG) emissions, and it can help optimize vehicle repairs and equipment replacement because of more-predictable and better-controlled maintenance. This paper describes a simulation model under development using the EXTENDSIM software package to examine scale-up issues and constraints of autonomous vehicles in comparison to a manual system. The software can predict and manage Key Performance Indicators (KPIs), such as productivity, safety, cost, equipment failures, fuel consumption, and tire wear under different road and load conditions. By breaking-down the various systems of an autonomous haulage truck and simulating the overall haulage system using a Monte Carlo approach, the model becomes a flexible and powerful tool to use within a mining organization. Direct comparison to a manuallyrun system can be done to show the cost and operational benefits of automation. Project managers can use this tool to guide decision-making about possible application of autonomous haulage trucks at a specific mine site.

May 1, 2010

By Brian K. Ayres

Inco Limited, Ontario Division is currently in the process of decommissioning the Whistle Mine site located near Sudbury, Ontario, Canada. The most significant component of site decommissioning involved relocating approximately 6.4 million tonnes of acid-generating waste rock to the open pit from two adjacent stockpiles. An engineered cover system was designed for the backfilled pit to reduce the long-term production of acid rock drainage. Geochemical modelling was conducted to assess the effectiveness of various cover options on the longterm water quality of the backfilled pit. Results obtained from performance monitoring of cover system field trials at the site and estimated full-scale construction costs were used to select an appropriate material for the cover system barrier layer. The two-dimensional soil-atmosphere model VADOSE/W was used to develop a calibrated model of covered waste rock based on field data obtained from the cover trials, which was subsequently used to predict net percolation and oxygen ingress through various cover system alternatives for site-specific climate conditions. Erosion and landform evolution numerical modelling was completed to assist in designing the runoff management system and final landform for the pit cover system. The potential impact of various physical, chemical and biological processes on the sustainable performance of the pit cover system was also considered in the design process. This paper provides an overview of the design and construction of the backfilled pit cover system.

Apr 1, 2005

By L. Li

Iron removal is a common procedure in hydrometallurgy of non-ferrous metallic ores. Chemical precipitation and solvent extraction are currently the main methods employed for separation of iron from copper leach solution. However, chemical precipitation methods have the problem of producing large amounts of iron precipitates, and/or requiring high temperature and high pressure conditions for precipitation. The precipitates are difficult to separate from the solution. Emulsification is a general problem for solvent extraction, which causes loss of extractants and contamination of the electrolyte. A common problem for solvent extraction and chelating ion exchange processes is the difficult iron stripping process. Therefore, finding an efficient and environmentally friendly method for iron removal is of great significance. In this paper, new processes of using ion exchange resins to remove iron from copper leach solution have been investigated. Salicylic acid, amino carboxylic acid, amino phosphonic acid and hydroxy-oxime resins were employed to adsorb iron from a simulated copper leach solution containing 40 g/L of Cu2+ and 36 g/L of Fe3+. It was found that a hydroxy-oxime resin, named Z-Fe, has excellent adsorption selectivity on Fe3+. Desorption behavior of the resin was studied by two step elution using dilute H2SO4 and oxalic acid solution, respectively. After optimizing the adsorption-elution processes, the extent of removal of iron from the simulated copper leach solution using resin Z-Fe was 90%, while copper recovery could reach 100% in closed circuit processing.

Jan 1, 2016

By M. Dosoudil

"Continuous pressure filtration is a modern process for the mechanical dewatering of flotation concentrates of coal and similar coal slurries. This method will give a lower moisture content than classical vacuum filtration, the improvement lying in the range 5% to 15%. Eighteen coal slurries have been examined in this survey. They are representative of a wide spectrum of filtered slurries. IntroductionDuring the last five years, a number of coal slurries have been tested either in the laboratory or with a pilot plant. The test pressure ranged from one to six bar. The results have been evaluated by mean s of a computer. Determination of the filter capacity and the resulting moisture content and energy consumption has been made with respect to the continuous pressure filter, Amafilter construction-type KDF (Fig. I) . Standard sizes of these filters are 60 m2, 90 m2 and 120 m2.The continuous pressure filter is a horizontal filter with a level tank. Six filter axles are mounted on a rotating main shaft, each with a particular number of elements attached. The elements rotate on their axes and move along a circular trajectory. Periodically the elements submerge into and emerge out of the slurry. A constant air pressure is maintained above the suspension, thus providing the pressure gradient necessary for filtration. The filtrate together with the dewatering air flows through the elements into the hollow axle and out of the filter."

Jan 1, 1987

By D. R. Wright

"The modest thermal efficiency of the steam turbine cycle essentially determines the heat required and, therefore, the coal consumption and ash production of pulverized-coal-fired powerplants. This paper emphasizes how some properties of coal and its ash can crucially affect the operation of a steam generator and its flue gas cleaning equipment. A brief reference to some siting factors and economics reaffirms the all-pervasive influence of the properties of coal and ash and establishes the importance of a firm supply of cooling water. The economics of scale remains a compelling factor in selecting the size of units, despite disappointing performances by some of the larger units. Environmental considerations suggest that smaller units still have a role to play. IntroductionCoal fuelled one industrial and economic revolution, beginning two hundred year s ago . It was the precursor of competing fuels, notably natural gas, oil and uranium, which eclipsed it in terms of convenience and rate of growth.The turmoil that now exists because of rapidly dwindling supplies of no-longer-cheap oil and the concerns about nuclear energy-justified or unjustified-exacerbated by an operating incident at the Three Mile Island Nuclear Powerplant, prompt speculation for a resurgence of coal, especially where it cangenerate electricity to replace energy from imported oil.The world's reserves of coal are not inexhaustible, although they are ample for several decades. Of greater import is the fact that the world's coal reserve s are more widely distributed than its oil reserves, and they appear less convenient as instruments of economic and political persuasion by opportunist powers. The crux is whether or not the world will accept all that a massive, if temporary, return to coal implies.Combustion of pulverized coal in steam generators to pro duce electricity is a 50-year-old, well-understood technique; it is undergoing continuous refinement to meet evolving environmental and economic criteria and is not found wanting. It is certainly the only technique available and technologically advanced enough to replace oil immediately on a large scale. Although it may take a decade to bring a new coal-fired powerplant into service, this delay is a reflection on nontechnical and administrative processes. Capital and operating costs of coal-fired powerplants are significant and subject to inflation, but, because of the accumulated experience in this field, the ability to control costs is better than for those energy processes which are less mature or still in embryo form. More exotic, soft energy systems, touted as the panacea for world energy problems, have still to prove themselves on the scale they are needed and under the stringent climatic and operating conditions coal-fired powerplants have already mastered."

Jan 1, 1980

By Otto Engel

"A multipurpose program for a hand-held programmable TJ-59 calculator and PC-100C printer facilitates the evaluation of various mineral processing tests and the calculation of mass and metal balances. Its application is demonstrated by some example problems. Detailed user instructions are given for each application.IntroductionThe program listed in Appendix I is written for a programmable Texas Instruments TI-591 PC-100C calculator I printer combination. The program is applicable for the evaluation of:1) screen analyses;2) flotation test s; and3) mass and metal balances.Each application is demonstrated by an example problem and corresponding detailed user instructions. The ""measured"" data in the examples are fictitious and do not represent a real operation.The steps in using the program are the same for each of the three types of application, viz.:1. Enter the number of product fractions and press ""A"".2. Enter the measured weights (0) of each fraction and press ""RIS"" each time. After the last fraction has been entered, the printer automatical1y displays the total weight.3. Press ""B"" to calculate the weight distribution (Y). Once ""B"" is pressed, the printer automatically displays the weight distribution of all fractions.4. If the accumulated weight distribution (EV) is also needed, press ""RIS"". The printer now displays these data. This step is optional and may be bypassed.5. Press ""2nd A"" to prepare for entering of the measured metal assay (M).6. Enter the measured metal assays of each fraction and press ""RIS"" each time. If analytical data exist for more than one metal, each data set has to be entered separately in one sequence.7. Press ""C"" to determine the ""calculated"" head assay (MA) of all fractions.8. Press ""RIS"" to calculate the metal distribution (R). Once ""RI S"" is pressed, the printer automatically displays the metal distribution of all fractions. This operation is optinal and may be bypassed if desired.9. Again press ""RIS"" to obtain the accumulated metal distribution (ER). This operation is optional and may be bypassed.10. Press ""D"" to calculate the gangue distribution in the concentrate (W). One ""D"" is pressed, the printer automatically displays the data for all fractions. This operation is optional and may be bypassed.11. Press ""RIS"" to obtain the accumulated gangue distribution (EW). This operation is optional and ma y be bypassed.12. For more than one metal, press ""E"" to clear the memory for storing the assays of the next. Then press ""2nd A"" and start entering the assays of the next metal as described previously (6 to 11). Steps 5 to 12 may be repeated as many times as desired."

Jan 1, 1982

By Scott Honan, Tassos Grammatikopoulos, Mike Johnson, Kelton Smith, Niels Verbaan, Ernesto Bourricaudy, Eric Larochelle, Rick Sixberry

"NioCorp is developing the niobium/scandium/titanium Elk Creek carbonatite resource deposit. The carbonatite phase contains significant niobium (0.71% Nb2O5), titanium (2.68% TiO2) and scandium (72 g/t) and is composed predominantly of calcite, dolomite and ankerite. Niobium is mostly (80%) contained in the pyrochlore and the balance in various Fe-Nb-Ti oxides, which also host most of the titanium. Scandium is distributed homogeneously throughout the ore mineral assemblage. The process flowsheet recovers separate niobium, titanium and scandium products. Scandium is extracted from whole ore hydrochloric acid leach solutions through solvent extraction, and is further refined through a re-leach and precipitation process. Scandium leach residues are treated with sulphuric acid to recover separate niobium and titanium precipitates. Both hydrochloric acid and sulphuric acid reagents are recycled within the flowsheet. This paper will discuss key bench and pilot test results (focusing on the scandium flowsheet) and will present a conceptual flowsheet developed by the project team for NioCorp at SGS Minerals.INTRODUCTION NioCorp is developing North America's only niobium/scandium/titanium project. The Elk Creek project is located near Elk Creek, Nebraska, and is the highest grade niobium project in North America and the largest prospective producer of scandium in the world. These elements are unique and valuable superalloy materials that are strategic and critical to many industries and national defense technologies. The project includes the Elk Creek Carbonatite (the Carbonatite) that intruded older Precambrian granitic and low to medium grade metamorphic basement rocks. Both the carbonatite and Precambrian rocks are interpreted to be unconformably overlain by approximately 200 meters (m) of Paleozoic marine sedimentary rocks of Pennsylvanian age. As a result of this thick cover, there is no surface outcrop within the Project area of the carbonatite, which was identified and targeted through magnetic surveys and confirmed through subsequent drilling. The available magnetic data indicate dominant northeast, west-northwest striking lineaments, and secondary northwest and north oriented features that mimic the position of regional faults parallel and/or perpendicular to the Nemaha Uplift."

Jan 1, 2017

"In flotation research, relatively little attention has been paid to understanding particle-bubble detachment phenomena compared with attachment processes. With CFD models now incorporating attachment/detachment kinetics, it is important to obtain more accurate formulations for detachment probability. The formula most often used is due to Bloom and Heindel (2002) who proposed that the rate of detachment would equal the product of detachment frequency, as previously estimated by other authors, and probability of destabilization, as estimated previously by Schulze. These two factors both account for the balance between stabilization and destabilization forces, so the product accounts for this effect twice. An integrated procedure has been followed to estimate the overall detachment rate by re-analysing the process. In this analysis, detachment rate is calculated as the frequency of eddy-aggregate interactions (or “collisions”) sufficiently energetic to cause detachment. The Bond number analysis of Schulze has been incorporated into the turbulence frequency analysis of previous authors in an integrated way. The new formulation has essentially the same type of dependencies as the previous model, but gives a lower detachment frequency. Detachment frequency has been calculated using the new formula for conditions relevant to an industrial flotation cell. INTRODUCTIONIt is well known that the effectiveness of froth flotation for separating different minerals is limited to the particle size range of approximately 10–100 mm (Trahar & Warren, 1976; Trahar, 1981). Fine particles tend to follow fluid streamlines around bubbles limiting the likelihood of bubble–particle collision, while coarse particles can be more easily detached from bubbles before collection can be achieved.Phenomenological models have been developed to quantify the physico-chemical aspects of flotation in order to better understand factors affecting these limitations, and to suggest ways of broadening the window of feasible flotation. Koh and Schwarz (2008) have incorporated these models into computational fluid dynamics (CFD) models of flotation cells, which have then been used for design and scale-up purposes (Schwarz et al., 2015). The models are based on dividing the process of bubble–particle interaction into three subprocesses: collision, adhesion and detachment. Of these, the hydrodynamics of bubble–particle collision and the probability of adhesion have been studied most extensively, while the dynamics of detachment have received relatively little attention from investigators."

Jan 1, 2016

By Xiaoqiong Wang, Daobing Wang, Fanbao Meng, Jianbo Wang, Hongkui Ge

"Shale gas has become an important unconventional oil and gas resources. Its effective development relies on comprehensive and accurate understanding of shale gas reservoirs. Rock mechanical properties is one of the important components of reservoir evaluation. Two adjacent black shale samples, which are cored from the depth of 1145 meters in Chongqing, southwest China, are subjected to acoustic emission(AE) test under uniaxial stress and compared with coarse grained granite. The results of synchronous AE, stress-strain and ultrasonic velocity experiments show that shale has weak anisotropy. Compared with granite sample, two shale samples are similar, but their strength, velocity and brittleness are quite different, indicating that shale has strong microscopic heterogeneity. TOC, XRD, SEM microstructure analysis show that total organic content, mineral composition and natural fractures are the main impacting factors for mechanical heterogeneity. INTRODUCTIONShale gas is a typical low-grade marginal resource, which is characterized by ultra-low matrix permeability and small single well control volume. In order to enable commerical development, complex hydraulic-fracture networks must be created in the shale to allow gas to escape from the micro/nano-pores and natural fractures where it is trapped in the rock (C. Clark et al.,2013; Ge et al., 2013). The development of shale gas requires accurate evaluation methodologies to evaluate shale reservoir properties and predict production. (Jarvie et al., 2007). Rock mechanical properties are an important part of the reservoir evaluation. It is significant for efficient drilling, completion and hydraulic fracturing to understand mechanical behavior of shale gas play (John, 2011; Wei, 2013).Rock mechanical properties mainly include heterogeneity, anisotropy, brittleness and acoustic emission activity (Lockner et al., 1992; Jerome et al., 2009; He et al., 2010; Liang et al., 2012). Shale mechanical properties are evaluated from laboratory tests following a complex workflow that covers tasks from sampling to testing (Md. Aminul Islam et al., 2013). It is common to include various experimental methods such as stress-strain curves, ultrasonic velocity and acoustic emission when evaluating the mechanical properties (Rao et al., 2006). Because of the presence of organic-rich matter, mineral composition orientation and natural fractures, shale tends to have strong anisotropy and heterogeneity (Deng et al., 2004; Wang et al., 2013; Hathon et al., 2013)."

Jan 1, 2015

By Hans D. Gougar

To meet an increasing demand for minerals, mining operations are moving to ever more remote regions. The lack of a local energy supply and infrastructure, coupled with social and regulatory demands for lowered environmental impact of mining operations, presents an opportunity for a seemingly unlikely competitor ? a nuclear power plant. The Modular Pebble Bed Reactor concept, currently in various stages of research and development around the world, offers a high degree of reliability and safety with minimal consequences for the local or global environment. The passive safety features of this design eliminate the need for the extensive active safety systems that add significantly to the cost of current water-cooled reactors. With the MPBR, as with all nuclear plants, there are no appreciable quantities of waste products released to the environment during normal operations. In contrast with conventional reactor designs, the MPBR would also remain radiologically safe even under the most severe abnormal circumstances. The key to the design is the fuel element. Enriched uranium microspheres are coated with various layers of pyrolytic carbons and silicon carbide to form a highly-temperature resistant particle that effectively retains all fission products. These particles are mixed with graphite and formed into 6 cm pebbles. A randomly packed vessel of such pebbles forms the reactor core through which helium is circulated as a coolant. Computer models and tests performed on actual pebble bed reactors confirm that fuel failure temperatures are not reached even during the most severe conceivable loss of coolant accident. The reactor drives a gas turbine cycle with resulting efficiencies as high as 48%, comparable to natural gas-fired units. The low price of uranium fuel and low maintenance requirements translates into competitive operating costs. However, high capital costs prevent the MPBR from competing with natural gas in most markets. In remote applications where no fossil supplies are readily available, the playing field is more level. This paper summarizes the features of two of the more promising candidates for remote applications and discusses the strengths of the MPBR from the perspectives of fuel supply and environmental impact.

May 1, 2002

By L. Tafaghodi, A. Hosseinpour

"Silicon is considered as the most appropriate semiconductor material for manufacturing solar cells because of its natural abundance and being nontoxic. The transferable knowledge and technology from the electronics industry and the long history of silicon-based semiconductors are also assisting the domination of silicon as the most common semiconductor material. Developing an environmentally and economically viable process for producing solar grade silicon has been one of the main challenges in the silicon industry in the past few years. Metallurgical refining processes have received significant attention because of their high productivity and low cost. Slag refining is one of the purification methods which is based on oxidation of the impurity elements, followed by its dissolution into a slag phase. This article presents a review of various slag refining processes that have been employed for purification of silicon and silicon alloys. SiO2, CaO, CaF2, CaCl2, Al2O3, MgO and Na2O are the major components of the slags used for silicon refining. These slags can be classified into three main categories including binary, ternary and quaternary slags.INTRODUCTION Silicon can be categorized into three different grades based on its application or purity: metallurgical grade silicon (MG-Si) with purity of ~98 %, solar grade silicon (SoG-Si) with purity of ~99.99999 % and semiconductor grade silicon (SeG-Si) which has the purity of 99.9999999 % (Johnston & Barati, 2010; Krystad, Tang, & Tranell, 2012; Tang, Øvrelid, Tranell, & Tangstad, 2009). Producing SeG-Si is carried out through an energy-intensive and complicated process named Siemens. This purification process is relatively slow and involves using toxic and corrosive reagents (e.g. Trichlorosilane). At present the majority of SoG-Si is produced via Siemens or Siemens-like processes and there is very limited production via processes dedicated to SoG-Si. Because of the difference in silicon specifications required in microelectronics and photovoltaic industry, and the cost and energy associated with the Siemens process, an interest has emerged to develop technologies dedicated to producing low cost SoG-Si (Istratov et al., 2003; Johnston, Khajavi, Li, Sokhanvaran, & Barati, 2012; Mitrašinovic, D'Souza, & Utigard, 2012; Wu et al., 2012)."

Jan 1, 2017

By E. M. Stiles

THE Wellington Lake power plant of the Consolidated Mining and Smelting Company of Canada, Limited, about 25 miles from Goldfields, Saskatchewan, is the second hydro-electric project operating in that Province, the first being the Island Falls plant of the Churchill River Power Company which serves the operations of the Hudson Bay Mining and Smelting Company at Flin Flon, Manitoba. The Churchill River project develops 90,000 h.p. at 56-ft. head; the Wellington Lake plant 3,300 h.p. at 75-ft. with pro-vision for an additional 3,300 h.p. unit. Churchill River power is trans-mitted at 110,000 volts over a 58-mile line of steel towers to Flin Flon and an additional 45 miles over a wooden pole-line to Sherritt-Gordon. Our steel tower-line is 22 miles long, and the voltage is 60,000; this choice be-cause certain such equipment was available from Trail. The diversion of 15,000? second-feet at 56-ft. head for 90,000 h. p. at Churchill river dwarfs our 500 second-feet flow at 75-ft. head for 3,300 h.p. In both cases, the main obstacles to be overcome during plant construction were the lack of transport facilities and the short open season. Let it be noted here that this paper deals mainly with those phases of plant construction which were particularly interesting to the writer. With-out these variations from the ordinary routine, this is just another power project whose story is better told by the accompanying charts and pictures. To many members of the Institute it is still just that; but I am writing for those who, like myself, have been too seldom responsible for major under-rakings at an appreciable distance from a railway siding. When it was planned in early 1937 to erect a 1,000-ton mill at our Box mine, both hydro and Diesel power were discussed. With ten years' ore in sight, even an expensive hydro project, such as ours turned out to be, produces kilowatts materially below the 2-cent operating cost of a Diesel plant using fuel-oil at 14 cents a gallon.

Jan 1, 1940

By B. Skrotzki, E. Augenstein, C. Rockenhäuser

"The aluminium alloy 2618A is an Al-Cu-Mg alloy with additions of Fe and Ni, which is designed for long-term operation at elevated temperature in transportation and aerospace industries. The alloy degrades due to coarsening and dissolution of GPB zones and coarsening of S-Phase precipitates (Al2CuMg). This work investigates the overageing process at the application relevant temperatures of 190 °C for durations ranging up to 25,000 h. The nm-sized precipitates were selectively imaged along the <001>a direction of the Al matrix using dark-field transmission electron microscopy. The resulting images were then evaluated and allow the statistically relevant determination of radii distributions and the average radius of the precipitates dependent on temperature and heat treatment duration. Ostwald ripening of the S-phase does not describe the ageing process adequately. Instead, the evolution of GPB zones during the initial ageing regime needs to be considered in addition to the coarsening process of the S-phase. DSC measurements were performed to determine the presence of GPB zones in different ageing states. This will allow a quantitative description of the ageing process and a comparison to samples aged under external load.INTRODUCTION Alloy 2618A is an Al-Cu-Mg alloy, which is part of the 2XXX series of aluminium alloys. It is used in aerospace and transportation industry due to its desirable material properties for long term operation at elevated temperatures (Polmear, 2006). Fe and Ni are added to form intermetallic compounds, which retain microstructural stability at elevated temperatures (Bergsma, Li, & Kassner, 1996; Elgallad, Shen, Zhang, & Chen, 2014; Oguocha, Yannacopoulos, & Jin, 1996; Wang & Yi, 2006). The size and distribution of the nm-sized S-phase formed from the supersaturated solid solution (SSSS) during heat treatments mainly controls the strength (Khan, Starink, & Yan, 2008; Liu, Zhang, Ding, Sun, & Chen, 2003; Parel, Wang, & Starink, 2010; Shih, Ho, & Huang, 1996; Wang, Starink, & Gao, 2006). The S-phase has the composition Al2CuMg and is orthorhombic under equilibrium conditions (Heying, Hoffmann, & Pottgen, 2005; Perlitz & Westgren, 1943). Early experiments proposed the following decomposition of the S-phase sequence during heat treatments (Hardy & Heal, 1954; Silcock, 1961):"

Jan 1, 2018

By Shigeru Sarata

A wheel loader is one of the main loading machines in open pit mines. The authors have been conducting research and development on autonomous operation of loading by a wheel loader. The most common loading method by a wheel loader is the ?V shape? path method. The loading operation consists of cycles of scooping from the pile, traveling to the dump truck, loading on the dump truck and return traveling to the scooping point for the next cycle. The traveling path includes a switchback in the middle of the path. The moving direction of the loader is changed at the switchback point. From observation of V shape path loading operations by experienced human operators, it seems that they control the bucket position between the scooping point and loading point on a shorter path for higher productivity. A new path planning method is proposed this paper, whereby a point on the center of the tip of the bucket is controlled moving from the initial point and the final point. The motion of the controlled point is generated by the wheel steering the wheel loader. The controlled point is moved along the direction to the final point; however, the motion and mechanism of wheel loader have restrictions, such as the velocity of the loader, the steering angle, and the steering angular velocity. Because of these restrictions, the path of the controlled point is not a straight line between the initial and final points. When this control method is applied between the scooping and the dumping points directly, the planned path is not stable in the leaving wing of V shape path. Therefore, the initial position of the wheel loader is set at the switchback point, then two approach wings to the scooping and the dumping points are made. The whole planned path is obtained by connecting the two paths. The shape of the planned path is strongly affected by the position of the switchback point, as well as the scooping and the dumping points. By simulation of path planning at different switchback points with the combination of the scooping and the dumping points, the paths for more effective loading are determined. The results of the simulation are presented in the paper.

Aug 1, 2013

By Peter A. Amelunxen, Richard LaDouceur, Courtney A. Young

"Many of the rare earth elements, the lanthanide series on the periodic table, are on the U.S. Department of Defense Strategic and Critical Materials list. In this regard, the U.S. Army Research Laboratory (ARL) has funded several projects at Montana Tech focusing on rare earth element recovery from natural resources. Current froth flotation operations utilize octyl hydroxamate for rare earth mineral extraction, however recovery is not ideal and flotation performance can be improved. Salicylhydroxamic acid (C7H7NO3) was identified as a novel collector due to similarities with n-octyl hydroxamate, notably the amine head group. Salicylhydroxamic acid is primarily used in the medical industry but due to the amine head group is ideally suited as a collector for rare earth mineral flotation.Parametric studies were performed for the flotation of rare earth minerals by modifying a wide range of variables. Mechanical variables of a 6L bench scale flotation cell, such as air inlet flow, rotor speed, and milling time for liberation were modified to elucidate energy input parameters for the desired minerals. Chemical parameters such as collector concentration and pH were varied to understand solution chemistry considerations of the salicylhydroxamic-rare earth mineral system. The study obtained a statistically significant experimental model for the flotation of rare earth minerals. A two stage compartmental model was also utilized for the determination of the first order flotation rate constants for each mineral. Optimized recovery of rare earth minerals was found to occur at near neutral pH ranges using salicylhydroxamic acid with maximum recoveries approaching ideal industrial standards although rare earth mineral grades were still not sufficient.INTRODUCTIONRare earth elements (REEs) are found in minerals that contain several REE which makes costeffective separation of the rare earths difficult. Significant scientific challenges have hindered mineral separation. The molecular similarity of rare earth elements results in minerals containing several REEs, such as bastnaesite [(Ce, La) CO3F]. This prevents efficient separation during concentration steps, for instance flotation, and has a direct impact on successive metallurgical processes. Consequently, concentration during flotation is of rare earth minerals (REM) as opposed to REE."

Jan 1, 2016

By D. Y. Li, C. D. Ma, T. Zhou, T. J. Cheng

In this paper, a number of experimental tests are carried out to study the strength difference on rectangular prismatic marble specimens with different height-to-width (H/W) rations. The specimens have a nominal size of 45×15 mm in the compressive cross-section (W×T) and different heights (H = 22.5 mm, 45 mm, 60 mm and 90 mm). It is to say that the height-to-width ratios are equal to 0.5, 1.0, 1.33 and 2.0, respectively. The quasi-static uniaxial compressive tests are finished by a servo-controlled INSTRON machine (the strain rate at about 10-5/s), and the dynamic compressive tests are finished by a diameter of 50 mm cylindrical SHPB apparatus (the strain rate reaching about 101/s). The rock failure process of marble specimens is captured by a high speed camera in order to distinguish the fracture propagation behaviour. It is found that the compressive strengths increase when the H/W ratio of marble specimen changes from 2.0 to 1.0 due to the end clamping effect both for quasi-static and dynamic loads. However, when the H/W ratio changes from 1.0 to 0.5, the apparent compressive strengths decrease both for the two loading conditions. The strength decrease of short marble specimens may be attributed to the change of failure mode from shear to slabbing, which can be identified by the fracture patterns of the specimens. Based on the uniaxial compressive tests, the slabbing strength of the marble was found to be about 40% of its UCS for the specimens with a nominal height-to-width ratio of 2.0. In addition, it is found that the dynamic increase factors (DIF) are affected by the specimen’s aspect ratios. It implies that the same aspect ratios should be used to compare the dynamic and static compressive strength of rocks. Meanwhile, both the static and dynamic tensile strengths of the marble are obtained by the Brazilian disc tests. The ratio of the dynamic tensile strength to the static tensile strength of the marble is about 2.68.

Jan 1, 2015

"Successive seismic waves may cause progressive weakening of a fault zone, which has been recognized as the mechanism of earthquake aftershocks. However, it is unclear that how a fault zone slips under each wave cycle and how slip displacement accumulates under continuous wave cycles. This laboratory study provides direct evidences on the slip process of a simulated granular fault zone dynamically induced by an incident wave without the effects of late-arriving and reflected waves. The experimental observations show forward and backward slip paths of the fault zone and partially recovered slip displacement after a wave incidence. The unrecovered slip displacement after each wave cycle can be accumulated until it reaches a critical slip distance for seismic faulting, which may reinterpret delayed triggering in earthquake dynamics. The limited interseismic period restricts fault self-healing in strength. The experimental results also indicate that the dynamically induced frictional slip on the fault zone is associated with a complex frictional system, including seismic wave radiation, frictional slip initiation and normal stress vibration. Different from the dynamically induced frictional slip on the fault zone, the statically induced frictional slip causes a permanent increase of slip displacement along the shear loading direction. INTRODUCTIONAn earthquake mainshock may induce aftershocks by suddenly changing external stresses applied to another fault zone in the near field (Kilb et al., 2000) and by slightly perturbing a fault zone from a critical steady state to stick-slip faulting in the far field (Gomberg and Davis, 1996). The dynamically induced frictional slip on a fault zone has been recognized as the mechanism of earthquake aftershocks (Marsan and Lengliné, 2008; van der Elst and Brodsky, 2010). Although earthquake aftershocks have been extensively studied by many seismological methods, a simplified laboratory fault zone can provide possible interpretation on real faulting and detailed analysis on a friction process (Dieterich, 1979; Nielsen at al., 2010). According to a few laboratory experiments related to the dynamically induced frictional slip on a simulated fault zone (e.g., Uenishi et al., 1999; Johnson et al., 2012), the slip process induced by successive seismic waves exhibits continuous motions. However, it is unclear that fault slip response under each wave cycle and slip displacement accumulation under continuous wave cycles."

Jan 1, 2015

By Yong Kang, Bingyuan Yan, Dandan Zheng, Xiaochuan Wang, Dengfeng Su, Dongyang Li

"According to the characteristics of rock mass and the directional cutting technology of water jet, a new idea of light shock controlled blasting with water jet slotting was put forward. Based on the fracture mechanics theory and the stress wave theory, the mechanism of damping with water jet slotting was analyzed. On the basis of the above, the evolution law of the pressure wave and displacement field during the blasting were simulated by FEM software ANSYS/LS-DYNA. The result shows that: the oriented slot plays a good role in orientation during the blasting, and makes the energy generated by gas released by the explosives gather at the tip of the oriented slot, which makes it easier for the main crack to expand along the oriented slot and indirectly reduce the stress effect on the protected object. Meanwhile, the energy of the seismic wave is reduced while transmitting through damping slot. Finally, compared with the normal blasting with damping ditch, the maximum acceleration is reduced by 15.62%, the maximum velocity is reduced by 52.99%, and the maximum displacement is reduced by 68.32%. INTRODUCTIONIn recent years, with increasing demand for energy and space, an increasing number of underground projects have been under construction. Drilling-blasting method, as a traditional main method for rock excavation, is still an indispensable means in the engineering construction. As is known, blasting vibration will cause the deformation and unstable of the existing building structures, so how to reduce the influence on the existing building structures caused by the blasting vibration has become the focus. Traditional shock absorption measures mainly include three kinds: the first one is pre-splitting blasting, the second measure is to change the parameter of explosive filling, and the last one is to excavate damping ditch between the protected object and blastholes. However, engineering practices show that: the protected rock may be damaged in the process of pre-splitting crack construction by blasting, the second measure is difficult in operating, and the third measure is troubled by large work quantity (Song Guangming, 1999; Lou Jianwu, 2004; Lou Jianwu, 2005; Li Xibing et al., 2008)."

Jan 1, 2015