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By M. Rafiee

Indoor physical security, as a perpetual and multi-layered phenomenon, is a timeintensive and labor-consuming task. Various technologies have been leveraged to develop automatic access control, intrusion detection, or video monitoring systems. Video surveillance has been significantly enhanced by the advent of Pan-Tilt-Zoom (PTZ) cameras and advanced video processing, which together enable effective monitoring and recording. The development of ubiquitous object identification and tracking technologies provide the opportunity to accomplish automatic access control and tracking. Intrusion detection has also become possible through deploying networks of motion sensors for alerting about abnormal behaviors. However, each of the above-mentioned technologies has its own limitations. This paper presents a fully automated indoor security solution that leverages an Ultra-wideband (UWB) Real-Time Locating System (RTLS), PTZ surveillance cameras and a Building Information Model (BIM) as three sources of environmental data. Providing authorized persons with UWB tags, unauthorized intruders are distinguished as the mismatch observed between the detected tag owners and the persons detected in the video, and intrusion alert is generated. PTZ cameras allow for wide-area monitoring and motion-based recording. Furthermore, the BIM is used for space modeling and mapping the locations of intruders in the building. Fusing UWB tracking, video and spatial data can automate the entire security procedure from access control to intrusion alerting and behavior monitoring. Other benefits of the proposed method include higher accuracy and robustness, more complex query processing, and interoperability with other BIM-based solutions. A prototype system is implemented that demonstrates the feasibility of the proposed method.

Aug 1, 2013

By Atulya Verma, Samantha Espley, Nashel Kalaka

Numerical modelling simulations of proposed mining sequences are used to evaluate mining induced stress concentrations and their migration associated with the progress of mining. This analysis is a standard practice for most prospective mining projects at various levels of feasibility study. The studies are usually initiated at the beginning of the mining cycle, on a global scale, and are maintained and updated throughout the life of mine (LoM) to identify or address local issues and the required remedies as and when needed. Developments in numerical modeling techniques along with advancements in computing technology and data storage/management capacity have given rock engineers access to a huge volume of data that needs to be analyzed and assessed. The most common approach to numerically evaluate stress concentrations and migrations in underground mines is to select the points of interest in a given volume such as the back of an excavation or points within pillars around critical infrastructure, and plot the stresses or a derivative of stresses over time to represent life of mine concentrations and migrations of stresses. The problem with this approach is the sharp gradient of stresses close to excavation boundaries. Slight changes in the location of selected points can change the stress concentration and migration patterns substantially and all generalized statements about LoM risk can be challenged in one way or another. For global stresses, the most common current approach of data analysis is by viewing series of pictures representing stress contours. In this approach, it is easy to overlook some critical detail and/or be masked by personal preferences of contour/picture representation. To overcome the problem of representing and analyzing huge volume of stress simulation data, the authors, through their experience at different mining operations, developed a volume-based technique to reliably evaluate mining-induced stress concentrations and migrations. The volume-based approach is for risk-based assessments of adjacent regions in the rockmass, in and around planned stoping excavations. The volume of interest is the entire ore body that is planned to be mined, but it could be just a part of the ore body depending on the specific use case. The risk identifiers are the induced stresses as compared to the strength of the rockmass. Over the LoM, the risk identifiers are tracked versus the corresponding excavation ratio of the zone. This approach is very effective in identifying the stages of mining that are contributing the most to the mining induced stress risk and the results can be used for proactive planning and mitigations measures such as alternative mining sequences, or stope sizes, or extraction methods. The approach has also been very successful in application at mature mines, particularly in assessing the re-initiation of mining in zone that has been dormant for some time. The volume-based approach allows for an assessment of the current state of the rockmass and the identification of future risks when planning resumption of mining activities.

Jan 1, 2023

By David Deglon, Martin Harris, Mehdi Safari

"This study investigates the effect of energy/power input on the flotation of a platinum ore in a pilot-scale oscillating grid flotation cell. Oscillating grids generate near ideal hydrodynamic environments, characterised by turbulence which is relatively homogeneous and isotropic. Secondary rougher feed and primary cleaner tail streams were floated in a pilot-scale oscillating grid flotation cell at power inputs from 0 to 2.5 W/kg, using 0.50 and 1.50 mm bubbles. From this study one may conclude that the effect of energy/power input on the flotation rate is strongly dependent on the particle and bubble size. Flotation rates generally increase with increasing particle size and decreasing bubble size. Increasing energy input generally leads to an increase in the flotation rate for finer particles and an optimum flotation rate for intermediate & coarse particles. Optimum conditions for intermediate/coarse platinum ore particles are using small bubbles at low energy inputs, or large bubbles at higher energy inputs. These results suggest that higher energy inputs are generally beneficial for the flotation of platinum ores as these consist predominantly of finer particles (-75 µm) and most industrial flotation applications operate with larger bubbles (1.0-2.0 mm).INTRODUCTIONThere is a considerable body of experimental and theoretical evidence to suggest that energy/power input plays an important role in flotation kinetics, particularly in the finer particle sizes where flotation efficiency is poor (Deglon, 2005). A number of excellent studies into the effect of energy on flotation kinetics have been carried out in impeller stirred cells (Ahmed and Jameson, 1985; Deglon, 2002; Pyke et al., 2003; Newell and Grano, 2006). Investigations using this type of cell have a number of limitations. The impeller influences particle suspension, bubble break-up and agitation in the cell. In addition, turbulence is highly inhomogeneous and anisotropic, with power intensities near the impeller orders of magnitude higher than those found elsewhere in the cell (Deglon, 1998; Koh and Schwarz, 2003; Schubert, 1999, 2008). These limitations have resulted in the development of novel cells for the investigation of energy input."

Jan 1, 2016

By Derrick Hunter, Pat Feighan, Keith Chrystall, David Wells

"Equipment which may be remotely operated, has some degree of on-board intelligence, and which for periods of time may operate autonomously, is referred to as telerobotic. Recent advances in electronics, computers and hydraulic equipment have dramatically reduced the cost and simplified the process of converting standard industrial equipment to telerobotic control. The benefits of telerobotic equipment include improved safety by removing the operator from dangerous situations, reduced maintenance costs and increased productivity. This technology has been proven in various military, nuclear, and police applications.The surface mining industry has expressed an interest in automation and is characterized by a willingness to use remotely operated equipment, however, the majority of telerobotic equipment currently in use is experimental or prototypical. Potential applications of telerobotic equipment for surface mining include remote operation of equipment near dangerous high walls and other unsafe areas, utilization of robotic trucks for routine hauling operations, and control of jointed equipment. In addition, component technologies of telerobotic systems are relevant to various forms of condition monitoring, operator feedback systems, and vehicle positioning.Attention must now be directed toward resolving more complex problems associated with enhancing feedback to the operator, improving the man/machine interface, and ultimately, improving efficiency. Removal of the human operator from the work site introduces significant complications in replacing the sensory inputs that an operator normally uses to efficiently run his machinery. These can be difficult to define and even more difficult to replicate remotely and may include restrictions pertaining to vision, hearing, and touch.In cooperation with Defence Research Establishment Suffield and the Alberta Research Council, Robotech Industries Ltd. is pursuing the development of additional technologies to further enhance an operator’s ability to control remote telerobotic equipment. These developments include a head-mounted display, additional control station displays and improvements to coordinated motion control software. Prototypes of these developments are expected to be completed and tested by the fourth quarter of 1997."

Jan 1, 1996

By T. G. Carter

"Damaging seismicity associated with deep faulting in both mining and civil excavations not infrequently occurs without warning, and often before proper mitigation measures have been put into place. Severe squeezing is also a common problem for excavating through deep major faults. While both problematic conditions are difficult to predict and characterize, there is often a need at pre-feasibility and feasibility level to more reliably estimate the possible level of risk posed by such geologic structures. This paper introduces some structural geologic techniques that have potential application for both mining and civil applications for aiding forewarning of the extent of these types of problem.INTRODUCTIONEncountering adverse faulting at depth in deep excavations, whether for mining or civil purposes can create serious economic and safety impacts. For deep mines or for deep tunnel projects, measures are available for aiding prediction of the extent of possible influence that large scale faults could create, but these techniques are rarely if ever applied as part of routine site investigation programs, or even as part of risk assessment evaluations. Several well established structural geologic methods of palao-history reconstruction have potential application for aiding forewarning of the extent of these types of potential problem by allowing estimates to be made of:• controlling stress orientations that might engender reactivation movement;• principal stress magnitudes that could lead to failure initiation, and• probable mechanisms of fault deformation - brittle (bursting) or plastic (squeezing).This paper explores several structural geological and rockmass characterization techniques that have application for unravelling fault structure of importance to deep engineering projects. Their application for mining or tunnelling purposes is advocated in conjunction with conventional rockmass characterization assessment approaches using GSI, RMR and/or Q to aid early recognition and definition of potential adverse ground condition behaviour associated with intersection of significant faulting at depth."

Jan 1, 2015

By K. C. Corin, M. S. Manono, J. G. Wiese

Depressants play a crucial role in the flotation of PGM bearing ores as they prevent naturally floatable gangue (NFG) from reporting to the concentrate. This action is regarded as critically important because less dilution of the concentrate means lower costs for downstream processes. However, abnormal water conditions (such as high concentrations of ions) in the flotation system can modify the selectivity of these depressants. It is well known that the existence of selected electrolytes in water can alter the behaviour of some polysaccharide depressants by enhancing their adsorption onto gangue minerals and thereby prevent naturally floatable gangue from moving into the froth phase. Concurrently these same electrolytes may enhance frothability, owing to their stabilising effect on the bubbles within the system. Plant water at various ionic strengths was investigated against depressant type and dosage in order to understand electrolyte-depressant interactive effects during the flotation of a Merensky ore, using entrainment, rate of NFG recovery, and total gangue recovery as proxies. The study showed that the rate of NFG recovery per unit mass of water decreased with increasing ionic strength at all dosages, however the total amount of gangue reporting to the concentrate increased with increasing ionic strength at all depressant dosages. Thus, this paper attempts to consider the effects of both ionic strength and depressant dosage as individual factors within flotation. It further looks to investigate whether any interactive effects exists between these two factors when considered simultaneously.

Jan 1, 2016

By M. A. Stogran-Baker, S. Cole

"Fluorspar mining occurred in the St. Lawrence area from the 1930s until the mid 1980s. In 2013, CFI discovered a new ore body, the AGS vein, which proved amenable to more economic open pit mining methods. A new mill was designed to produce 200,000 tonnes per year of high quality, acid-grade fluorspar concentrate. The simple mill flowsheet includes crushing, dense medium separation (DMS), grinding, sulphide flotation, pulp thickening, fluorite flotation, thickening, and concentrate filtration. The type of flotation cell used is being installed for the first time in North America. Site clearing commenced in the spring of 2016, followed by mill building erection completed by the fall of the same year. Civil and mechanical installation as well as site-wide construction was completed by the end of September 2017. Commissioning commenced, and at the time of paper submission mill production is on track to ramp up to full capacity by the beginning of 2018. This paper will focus on the use of fluorine NMR analysis applied to fluorite and the development of on-stream analysis, flotation cell selection and the decision to install the new cells, and the water control program designed to maintain process control with the least possible environmental impact.HISTORY St. Lawrence is located on the south-eastern coast of the Burin Peninsula in Newfoundland and Labrador. The first occurrence of fluorspar in the St. Lawrence area was recorded in 1843 by British geologist J.B. Jukes (DNR 2010). Fluorspar was likely extracted in small quantities prior, however commercial fluorspar mining did not commence until 1933 at the Black Duck Mine. The Black Duck Mine operation processed ore by washing and screening – acid-grade was hand-picked from the oversize, the undersize was sold as a lower grade product. The Black Duck Mine was closed in 1941 (Wilson 2010). The American Fluorspar Limited (New Fluor) commenced operations on the Director vein in 1936, and was bought by Alcan in 1942 (Cooper 2012). Alcan also developed the Iron Springs as well as the Tarefare deposits. The Black Duck Mine mill had closed, and a new mill was built. This new mill crushed the ore prior to dense medium separation, the sinks of which were sent to Quebec for use in Alcan’s aluminum smelter (CFI 2016). Alcan shut down it’s mining operations in 1977 due to the dropping price of fluorspar as well as labour disputes. In 1986, the British-based Minworth Limited began producing ore from underground at Blue Beach North and Blue Beach South, as well as from open pits at Tarefare and Director veins (Cooper 2012). A new mill was built by Minworth in order to process the ore using flotation to produce an acid-grade concentrate. The low price of fluorspar caused Minworth to shut down operations in 1990. Whilst exploration has been ongoing, no mining had occurred in the area since 1990."

Jan 1, 2018

By Eamonn F. Maher

Superconductivity is one of the most remarkable scientific phenomena ever investigated. It is the phenomenon whereby some materials exhibit zero resistance to the passage of an electric current when cooled to low temperatures, and requires a quantum mechanical explanation. Four Nobel prizes in physics have been awarded specifically on the subject of superconductivity, with many more enabled by superconducting technology. For example, particle beams are generated in accelerators and manipulated in ?particle beam lines? in the ?Big Physics? projects around the world eg. at CERN, Geneva, leading to major discoveries in fundamental particle physics. Similarly, at the JET Propulsion laboratory near Oxford, U.K, controlled nuclear fusion has been demonstrated, and magnetic containment of plasmas is key. In the chemical and biological sciences high field NMR spectroscopy has become indispensable for examining organic matter, revealing the mysteries of the workings of cells, genetics, and in the development of new polymers and pharmaceuticals. With all these very advanced uses for superconducting magnets, it is easy to forget that superconductivity is big business, not just a scientific curiosity. MRI (Magnetic Resonance Imaging) superconducting magnets, the key component of high resolution body scanners, use approximately half of the world?s superconducting wire ? the other half being mostly used in accelerator magnets. The MRI market is about 3 billion dollars per annum, and one MRI magnet uses 200km of wire. New applications for superconducting magnets are now appearing including ?Catheter steering?, enabling much shorter timescales for life-saving brain tumour removals and ?Functional MRI?, a whole new area in patient diagnostics. Whilst the use of low temperature superconductors (LTS) is now well established commercially in superconducting magnets and niche electronic applications, the application of LTS in electric power distribution and transport has been very limited to date. It is now more than fifteen years since the so-called High Temperature Superconductor (HTS) materials were discovered: these can be operated at liquid nitrogen temperatures rather than liquid helium temperatures. However, materials processing and scale-up issues have prevented their widespread use, and in particular the required price/performance criteria are only beginning to be reached except in certain niche markets. BSCCO (Bismuth Strontium Calcium Copper Oxide) tapes up to one km long are now readily available, and have been demonstrated in high current cables for power distribution networks, but the general consensus is that 1) it is difficult to reduce the price much further because of the silver matrix required and 2) in applications where coils are required eg. motors, generators, transformers etc the properties of BSCCO are rather poor because of the critical current dependence on magnetic field. Magnetic fields are always associated with coils and windings, and such fields are of course fundamental to the operation of all electrical machines. YBCO (Yttrium Barium Copper Oxide) however, has good characteristics in field and for the last few years there has been intensive research and development costing several tens of millions of dollars worldwide into the scale-up of production of so-called ?coated conductor?. This ?second generation? tape can be produced by any of many different film deposition techniques, with more or less success for short lengths, but as yet it is unavailable in lengths more than a few tens of metres.

Oct 1, 2003

By Jean-Pierre Birat, François Hanrot, Gérard Danloy

Global warming presents an enormous challenge to the steel industry, which is both carbon-intensive and energy efficient. Lean production can provide some short-term emission mitigation, at the level of the Kyoto requirements. In the middle term, more use of scrap will also help alleviate emissions. But to reach much larger reductions in GHG emissions, on a par with the likely targets that will be set after the Kyoto period, the steel industry will have to imagine new production paradigms, which constitutes its most formidable challenge for the years to come. Carbon capture and sequestration, processes leaner in carbon use, electricity and hydrogen from green sources will have to be added together in a patchwork of process routes, which will have to be developed at great risk in the next decade, hopefully through broad international cooperation.

Jan 1, 2004

By G. D. Markland

The Moose Mountain mine is located in a belt of Precambrian volcanic rocks situated 20 miles north of Sudbury, Ontario. It was the first iron mining operation in the Archean iron-formations of the Canadian Shield. The ore is believed to have been formed in an environment of active volcanism, being part of a pyroclastic and volcanic series where only the iron-formation and chert qualify as chemical sediments. The volcanic environment, subsequent regional tectonics and metamorphism produced orebodies which differ from the main sedimentary iron ranges of the world in such features as continuity, grade, structure and metallurgical characteristics. The orebodies occur as relatively small lenses which have been complexly folded, faulted and intruded by acidic and basic dykes.

Feb 1, 1966

By G. D. Markland

"The Moose Mountain mine is located in a belt of Precambrian volcanic rocks situated 20 miles north of Sudbury, Ontario. It was the first iron mining operation in the Archean iron-formations of the Canadian Shield.The ore is believed to have been formed in an environment of active volcanism, being part of a pyroclastic and volcanic series where only the iron-formation and chert qualify as chemical sediments. The volcanic environment, subsequent regional tectonics and metamorphism produced orebodies which differ from the main sedimentary iron ranges of the world in such features as continuity, grade, structure and metallurgical characteristics. The orebodies occur as relatively small lenses which have been complexly folded, faulted and intruded by acidic and basic dykesAlthough the basic mining and beneficiation methods are simple, detailed geological control in exploration, planning and operation has been necessary to apply detailed selective techniques to the large-scale open-pit methods necessary in profitable iron mining.The milling and pelletizing processes are sensitive to minor variations in ore grade, grain size, fabric and mineralogy. Although detailed correlations of geological information and mill performance are still not entirely satisfactory, general working relationships have been determined with simple testing procedures. These are of in-creasing use in forecasting production and in ore-blending processes.The application of geology to mining and milling operations at Moose Mountain represents a departure from general practice in iron ore operations."

Jan 1, 1966

By C. A. D' Odorico

The zinc pressure leaching (ZPL) plant at Teck Cominco's Trail Operations was started up in 1981 and represented the world's first commercialization of the technology. From the outset, the process was designed to operate using iron-rich Sullivan Mine zinc concentrate. When the Sullivan Mine reached the end of its life in 2002, the ZPL plant underwent a significant process change with the treatment of 100% Red Dog zinc concentrate. Through careful improvements to existing plant processes, controlled changes to plant operating parameters and a rapid adjustment to the modified process by operations personnel, the plant has been successfully converted to processing a feed of 100% Red Dog zinc concentrate. This paper discusses the challenges faced during the conversion and describes the modifications to plant operating procedures, as well as changes to plant processes.

Jan 1, 2004

By R. P. Charbonnier

"To understand the operation of jigs and other separating processes based on differences in gravity, it is desirable to analyse the motion of various particles in given media under specific conditions. A summary of the earlier theories shows that they lead to unsatisfactory or excessively complicated formulae in cases such as coal jigging. By adopting a simplified theory of the motion of particles in a fluid, the size and duration of the initial accelerated motion of a particle falling in hindered settling can be calculated. Based on this mathematical analysis, examples referring to actual coal jigging practice show that it is desirable to prolong and/or repeat, as frequently as possible, the optimum conditions corresponding to an effective acceleration of the particles. The separation is then obtained according to gravity rather than to particle dimensions, as would be the case if the velocity of the particles• were allowed to approach its terminal value. To achieve this gravity separation, it is suggested that the suction phase of the jigging cycle be artificially prolonged and the frequency of pulsations increased as much as possible for washing the coals of smaller sizes."

Jan 1, 1959

By V. G. Papangelakis, G. A. Moldoveanu

"Rare earths adsorbed on clay minerals are easily recovered via ion exchange during leaching with inorganic monovalent salt solutions. The leaching efficiency of various salts at 0.5M and 25°C was investigated as a function of cation type and salt system (sulphates vs. chlorides). (NH4)2SO4 was identified as the lixiviant of choice and a procedure was established to investigate the influence of lixiviant concentration, temperature, pH and agitation on desorption kinetics and REE extraction levels. It was determined that the kinetics were fast and the optimum leaching conditions (for >80% total REE extraction) required pH below 5 and moderate temperatures (<50°C). INTRODUCTIONRare earth elements (REE) are at the core of numerous advanced applications due to their various uses in high strength permanent magnets, lasers, automotive catalytic converters, fiber optics/superconductors, and electronic devices (as phosphors in TVs and display screens for computers and cell phones). Because of the ongoing development of new technologies, there is an increased demand for REE in the international market, with emphasis on identifying new resources to insure an adequate supply for present and future use. World production of rare earths is dominated by China, the United States and Australia; however, in terms of resources, China dominates the world potential with reserves estimated to be over 90% of the total (Chen, 2011).The main commercially significant REE sources, as reviewed by O’Driscoll (1991) are bastnasite (carbonate) and monazite (phosphate) minerals, containing up to 70% wt. rare earth oxides (REO). In spite of being high grade, these ores are associated with elevated recovery costs due to difficulty in mining, separation and beneficiation. Moreover, aggressive conditions are required to solubilize the REE from the mineral, such as leaching with hot, concentrated acids or baking in 70% NaOH (Gupta & Krishnamurti, 2005)."

Jan 1, 2012

By A. Monballiu, J. A. Martens, Y. W. Chiang, A. Van Audenaerde, R. M. Santos, T. Van Gerven, B. Meesschaert

In this work, bioleaching of non-sulphidic materials by applying chemoheterotrophic bacteria and fungi is studied. It was found that the tested fungus, Aspergillus niger, leached substantially more nickel from olivine than the tested bacterium, Bacillus mucilaginosus. A. niger also outperformed fungal species Humicola grisae and Penicillium chrysogenum in the leaching of olivine. Contrary to traditional acid leaching, the microorganisms leached nickel preferentially over magnesium and iron. On average, a selectivity factor of 2.2 was achieved for nickel compared to iron. This can potentially facilitate postprocessing of the leach liquor and reduce the cost. The impact of ultrasonic conditioning on bioleaching was also tested, and substantial increase in nickel extraction with A. niger was observed. This was credited to an increase in the fungal growth rate, the promotion of particle degradation, and the detachment of the stagnant biofilm around the particles. Furthermore, ultrasonic conditioning enhanced the selectivity of A. niger for nickel, resulting in a selectivity ratio for Ni/Fe equal to 3.5. The chemical resistance of the selected microorganisms to several heavy metal and metalloid (As(III,V), Cd, Cr(III,V), Ni, Pb, Zn) was evaluated. It was found that, with the exception of As(v) and Cd, A. niger has high tolerance to these components. Therefore, this biohydrometallurgical route can potentially be applied to non-sulphidic wastederived materials, such as industrial slags, ashes and sludges.

Jan 1, 2014

By Noel Brien, O&apos

General: National Asbestos Mines Limited has operated an asbestos mine and mill near Thetford Mines, Quebec, since 1958. As a result of additional exploration of the orebody in 1962-63, it became apparent that long-range mining plans would have to be revised to allow for a large increase in both ore and waste tonnages. It was decided that the task of checking out possible mine designs could best be analyzed by a computer to obtain data from which an optimum open-pit configuration could be plotted. Object: It was desired to arrive at an optimum open-pit configuration with an over-all pit slope of 45 degrees and a minimum operational width of 200 ft. at the bottom. Calculations were based on assay values from diamond drill holes in cross sections of the mine. The computer&apos;s assignment was to select and describe, by coordinates, the optimum cross section for the mine. Mine engineers then assembled the various optimum sections to produce the pit outline. As this would not necessarily result in a practical mining arrangement, the computer also provided alternate solutions,

Jan 1, 1965

THE Michipicoten area, one of numerous iron-bearing "Archean" segments in the Shield, contains two main types of iron formation, a normal Keewatin-type, consisting of interbanded chert, siliceous magnetite and jasper, and, gradational to this, a carbonate-sulphide type which contains large de-posits of siderite and pyrite. The carbonate-sulphide type of iron formation bears a direct and intimate relationship to the volcanic development of the area; it there-by affords some insight into genetic problems of Archeanron formation in general. The purpose of this pa-per is to summarize the geological setting of Michipicoten iron formations and to briefly review genetic aspects of recent work in the area. GENERAL GEOLOGY in largely by assorted volcanics and sediments of the Michipicoten series and younger, regional granite masses. (Fig. 1). The Michipicoten series comprises a thick assemblage of mixed flows and pyroclastics together with elastic sediments and banded iron formations. The volcanics belong to the Andesite-Rhyolite Association, and characters-

Jan 1, 1961

By H. Aminian

Gold powders have many important industrial applications. In this paper the available processes for the preparation of gold nano and micron sized powders are described. The attention has been given to hydrometallurgy route and the recent works and achievements in controlling the powder morphology are highlighted.

Jan 1, 2011

By L. O. Cooper

IN THE operation of most mines, hoisting ropes, made of steel, play a very important part in the conveying of men and material between surface and the underground workings. It is obvious that, in order to maintain a maximum degree of safety, certain restrictions must be placed on the loads that may be carried by hoisting ropes, as well as on other factors that may affect the life of the rope. It is the purpose of this paper to suggest ?a new method of defining the necessary restrictions. The three main stresses in a hoisting rope are the static stress, bending stress, and dynamic stress. Crushing stresses, which are also present, are largely indeterminate and may best be allowed for by proper grooving of drum and sheaves, by adequate inspection of cross-over points, and by limiting the number of layers on the drum. They will, therefore, not be considered in this analysis. In the ?recent Ontario regulations, the limiting conditions for the main stresses are specified separately. The static stress is limited by setting a minimum static safety factor of 5.0 The dynamic stresses are allowed for by specifying a minimum capacity factor of 8.5, which has the effect of increasing the safety factor required at smaller depths in a uniform manner. The bending stresses are limited by calling for a drum-dia./rope-dia. ratio of at least 60 for ropes up to 1 inch in diameter and 80 for ropes greater than 1 inch in diameter. One disadvantage of this method is that the controls are too rigid and do not allow the operator sufficient freedom of action within safe limits.

Jan 1, 1951

"Beneficiation of low grade ores is the process of increasing the grade of a mineral through unit operations that remove and separate the waste (or gangue) material from the valuable mineral that can then be used for further processing or direct use. Important factors when deciding upon a beneficiation program are the feed grade, mass yield and the metal recovery. As lower grade ores are being processed beneficiation is a critical process. How predictive is laboratory test work for “as built” operating projects? Beneficiation includes all or some of the available unit operations to produce a beneficiation flow sheet i.e. associated unit operations including but not limited to optical sorting, radiometric sorting, crushing and screening, coarse cobbing, jigging, dense media separation (DMS), spirals, magnetic separation, flotation, thickening, filtering and drying. Reference to specific projects and the approach developed in formulating a beneficiation flow sheet and a comparison of difficult and simple beneficiation flow sheets are cited. INTRODUCTIONReserves of high-grade iron ores are reducing all over the world, at an alarming rate, over the years as a result of the rapid increase in demand for steel particularly from Japan and then China. The recovery of mineral value from the low-grade ores using present technology is more expensive than DSO ores due to high energy and capital costs. Beneficiation is defined as a variety of processes whereby extracted ore from mining is reduced to particles that can be separated into mineral and waste.Various physical properties of an ore can be exploited to separate a low grade fraction including variation in hardness, density, reflectance, conductivity and magnetism.""Beneficiation"" of iron ores includes concentration, generally by physical removal of unwanted gangue. Also considered beneficiation is the regulation of product size, or other steps such as agglomeration to improve its chemical or physical characteristics prior to smelting."

Jan 1, 2012