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By Murray W. Grabinsky

The in situ performance of Cemented Paste Backfill (CPB) systems can be monitored to improve understanding of the paste?s behaviour and therefore optimize the geomechanical design of the cemented paste backfill system (i.e., minimize binder content, minimize fill barricade complexity, maximize fill rate-of-rise during backfilling, and minimize cure time before resuming production blasting in proximity). However, undertaking such a monitoring program is inherently complex, because the rate-of-rise and accompanying self-weight induced stresses occur at a time rate that is similar to the rate of hydration and associated increase in the paste?s stiffness and strength. In addition, arching within the stope complicates the overall stress distribution. Therefore, to obtain a complete picture of the CPB?s response, it is necessary to measure several variables (3-D total pressures, water pressures and suctions, hydration rates, and blasting induced vibrations) at a given ?point?, and take all such measurements at many points throughout the fill mass as well as at barricade locations. The overall testing program can therefore be logistically difficult to implement and have an apparent high cost. However, if the program is successful, the benefits arising from improved mine design can significantly outweigh the seemingly high initial capital and labour costs of the monitoring program. A case study involving an instrumented paste fill in a tall and narrow Alimak stope is briefly outlined. Plans for a similar experiment in a large long-hole stope are then considered.

May 1, 2008

By R. Tessier, R. Grant, C. Bazin

"Brunswick Mining has investigated grinding media optimization for the purpose of improving the flotation feed and regrind product size distributions to enhance metal recoveries. The paper presents findings in the on-going testing of various sizes and shapes of grinding media. Breakage rates are used as an aid to assess the effect of grinding media. Results of empirical and phenomenological analyses demonstrate the importance of adequate selection of media sizes on the milling operation.INTRODUCTIONBrunswick Mining and Smelting operates one of the world's largest lead and zinc mine near Bathurst, New-Brunswick. The No. 12 ore body is an extremely fine grained volcanogenic massive lead, zinc, copper, silver, iron sulphide body between two metamorphosed sedimentary and felsic volcanic rock units. Pyrite content is about 60% with 20% non-sulphide minerals, mainly silica and chlorite. The operation is currently processing 10,500 tonnes of ore per day in conventional crushing, grinding, differential flotation and dewatering circuits. Details on the circuit can be found elsewhere (e.g. Hendriks and Ounpuu, 1985; Grant et al., 1991).The mill has operated for more than 25 years and despite the past milling experience, there has been much disagreement as to the required grind size. Since 1964, fineness of the flotation feed ranged from 60% to 80% passing 400 mesh (37µm) and averaged slightly over 71%in1992. Results from mineralogical analysis (Petruk and Schnarr,1981; Coleman, 1988), Brunswick metallurgical laboratory (Grant et al., 1991; Shannon et al., 1992) and Lakefield pilot plant tests (Hendriks, 1984; Hendriks and Ounpuu, 1985) clearly indicate that improved metal recoveries can be achieved by an increase in the fineness of grind, and more specifically by maximizing the amount of material in the 15-25µm range."

Jan 1, 1993

By K. Tada

A surface of a magnesium slab (hereinafter, referred to as Mg slab) or magnesium alloy slab (hereinafter, referred to as Mg alloy slab) becomes black with the use of conventional manufacturing methods. The methods also involve a danger that an explosion of the molten magnesium occurs through contact with cooling water. Thus, it has been impossible to produce a slab having a smooth surface. In the present method, a molten magnesium alloy is supplied into a mold, which is sheltered from the surroundings, from a pool in tundish, which is shielded from the surroundings. AZ31B slab formed in the mold is drawn horizontally out to the outside from an outlet of the mold by revolving of the pinch rolls. A cooling water is jetted at an acute angle onto the slab on the outer side of the mold outlet. Further, an inert gas is sprayed at the inner side of the mold outlet in order to seal in a gap between a free surface of the molten magnesium alloy and a sheltered board surrounding an upper surface of the mold. As a result, oxygen and droplets of the cooling water are prevented from running back to the mold side through the gap. AZ31B slab has a smooth surface condition and high quality without a gas porosity, a segregation or the like. Further, the slab has a size of a width of 100 to 120 mm, a thickness of 5 to 20 mm and a span of 10 m or more.

Jan 1, 2006

By Victor A. Sowa

"Abstract - In 1938, a body of goethite and hematite was discovered beneath Steep Rock Lake near Atikokan, northwestern Ontario. This was at the time the largest and richest undeveloped iron ore body in North America. Mining began in 1944, fast-tracked by the needs of World War II, and through 1979 produced 79 Mt of 56.5% Fe. Production required the diversion of the Seine River, draining of Steep Rock Lake, building of a railroad, and a 25-fold increase of the local population. The mining project, at the time, was the largest project of its type undertaken in Canada. The current concepts of sustainable mine development and mine closures have advanced considerably since the period of operation and closure of the Steep Rock mines, and those operations would probably not have met current expectations of sustainability. However, some of the post-closure aspects of the mines provide illustrations of components of sustainability, which could form part of a basis for a post-mining sustainable land use plan. It is concluded that some of these components were successful in meeting current expectations of sustainable use, and although some aspects are unique to the circumstances at the Steep Rock mines, others could be applicable at other mine sites."

Jan 1, 2003

By J. C. Salas, A. Weishaupt, J. A. Guzman

The origins of the electrorefining process date back to 1869, when the first ER cathodes were produced at Pembrey, South Wales. By the time that Pembrey was closing, Chuquicamata tank house was under construction, initiating in 1915 a long history of electrolytic cathodes production. Initially electrowon cathodes and later electrorefined cathodes were produced. During the history of Chuquicamata tank house, there have been several challenges associated with the quality demanded for electrolytic copper. Among them, the transformation from electrowinning to electrorefining in 1952, the onset of the direct commercialization of ER cathodes and the phase out of wire bars in the 80s, several technological changes including the implementation of permanent cathodes, and certainly the constant increase in complexity of the anodes refined. This paper explores the manner in which Chuquicamata has addressed these challenges and examines its links to process characteristics, which have been necessary to maintain a product quality according to market requirements and a brand, “CCC”, that is widely recognized worldwide. INTRODUCTION Located in the north of Chile, in the Atacama Desert, Chuquicamata is an open pit copper mine that for many years has played a relevant role in the global and local mining industry. Known from prehispanic times, the Chuquicamata deposit was initially developed between 1912 and 1915 by the Chile Exploration Company, the operating company of the Chile Copper Company controlled by the Guggenheim Brothers in the USA (Yeatman, 1916). Officially inaugurated on May 18th, 1915, by the President of Chile who pressed a button in Santiago sending a telegraph signal to the power generation plant specially built in Tocopilla, 1500 km north. It signaled the beginning of generating energy, sending it to Chuquicamata, another 140 km east (“El mineral de Chuquicamata”, 1915), marking the beginning of its industrial operation.

Jan 1, 2019

By W. A. MacWilliams, R. G. Reynolds

"This paper describes, for the first time, a patented method of extracting sodium sulphate from a natural deposit in Western Canada. The method resembles, but is not, strictly speaking, solution mining. The fact that a plant based on this method has been in successful operation since late 1969 will be of added interest. The deposit in question is located near Metiskow, Alberta, and conventional surface recovery methods could not be applied because of heavy concentrations of mud. Considerable pilot work went into the separation and recovery process on which the plant operation is based. The history of the industry is covered briefly as background to this development. Today it is clear that the method has broader application within the industry and, in concept, may generate interest in many other applications."

Jan 1, 1973

By K. Reinharter, J. Schmidl, D. Gregurek, A. Spanring

Copper smelting furnaces are typically lined with magnesia-chromite refractories, which are exposed to multiple and complex stresses. The selection of the processing route, furnace type and slag system will be dictated by the specific ore type available, this will determine the individual refractory wear. This paper evaluates the common refractory wear mechanisms as observed in the copper Peirce-Smith converter and in the copper anode furnace. The chemical factors include corrosion caused by fayalite type slag and sulfur supply, as well as, by Cu-oxide attack. Changes in the temperature during the furnace operation (thermal-shock) create stresses in the brick lining which can only be absorbed in limited extent. Mechanical factors include erosion, caused primarily by the movement of the metal bath, slag and charging material, as well as, stresses in the brickwork due to punching. Finally improper lining procedures can also effect the service life. All these wear parameters lead to severe degeneration of the brick microstructure and a decreased lining life. Therefore, a detailed investigation and understanding of the wear mechanisms through “post mortem studies” together with thermochemical calculations by FactSageTM software is an important prerequisite for the refractory producer. Based on these research results, combined with specific process knowledge, appropriate brick lining solutions for copper processing furnaces can be recommended. INTRODUCTION The refining of copper includes converting of matte or black copper into blister copper for final fire refining process in the anode section. Typically Peirce-Smith (PS) converters are in use. Other technologies include Hoboken Converter, TBRC but also Flash Converting Furnace and bath smelting furnaces (ISA, Ausmelt) (Davenport et al., 2002). For fire refining two types of furnaces are used – the rotary furnace type is dominantly used in the primary production route while secondary smelters tend to use hearth refining furnaces which are more suitable for scrap melting. Installed working linings are based on magnesia-chromite bricks but especially in the anode refining section the application of alumina-chromia bricks have become more popular in the recent years. It comes without saying that, to some extent, large variations in the slag composition can be observed from the data provided to RHI Magnesita during post-mortem studies of used refractory samples and this needs to be addressed properly during the selection process of refractory linings.77

Jan 1, 2019

By Robert T. McKnight

"Traditional techniques for valuing resource projects companies have been primarily based on discounted cashflow methods (DCF) or by comparison to similar projects with an apparent market capitalization. Many resource projects are really forms of options to invest rather than a future cashflow stream. Employing the DCF method to value a resource project which is really an option to invest, can dramatically underestimate the real value of the project. The analytical tools required to evaluate options, while more complicated than the usual spreadsheets used for DCF, are becoming more easily available and usable by managers. This paper will discuss the background of options valuation and some of the tools which will make it easier for managers to estimate the value of projects and companies which have significant real option values.ResumeBob McKnight is a graduate of the University of British Columbia in Geological Engineering, supplemented by an MBA from Simon Fraser University. Following several years in the oil patch with Cities Service and Brascan, Bob returned to Vancouver in 1979 to work for Wright Engineers. He subsequently went on to work for Cassiar Mining, Getty Resources and Endeavour Financial before joining Pincock Allen & Holt Ltd. in 1998. His experience ranges from exploration to feasibility studies, financial evaluations of mining and oil & gas projects, due diligence, project finance, valuations and mergers and acquisitions. He has extensive international mining experience pertaining to such countries as Chile, Mexico, Uruguay, Thailand, Indonesia, Angola, Papua New Guinea, Kazakhstan.What are Options?Options have been around for centuries. They were familiar to Roman and Phoenician traders who were shipping cargoes from Mediterranean seaports. In the financial world, options are types of contracts that generally include the right, but not the obligation, to buy or sell a share, currency or commodity. The underlying commodity price or share price changes are assumed to be lognormally distributed. In this context, options are of two general types, ""call"" options and ""put"" options. Call options have the characteristic of having the right to buy a tradable commodity or currency at a predetermined price for a specified period of time. For the owner of call options, they become more valuable as the price of the underlying commodity increases. For the seller of call options, these options become an increasing liability as commodity prices rise, since there is the obligation to sell the commodity at a predetermined (perhaps lower-than-market) price. This characteristic of call options recently became high profile with the sharp rise in gold prices last year. The value of gold call options sold by certain producers increased their associated liabilities to the point where margin calls were made."

Jan 1, 2003

By Paul A. Glapa

Quality is much more than providing a product that functions properly. True quality is a way of thinking, a way of doing business, and, ultimately, a way of satisfying a customer?s long-term needs. A true commitment to quality requires a top-down management commitment, with a willingness to change what needs to be changed and to expand upon ?best practices? that are already done well. Is there a cost to creating and maintaining a quality program? Of course there is, but the cost of not having a focused program is much greater. We have come to regard quality as an investment that pays dividends to both the supplier and customer. The lack of quality costs everyone and the customer pays the ultimate penalty. With modern, highly engineered surface mining equipment the end user calculates cost in terms of lost production (revenue), not simply the cost of the part. Bucyrus International, Inc. is a company that has listened to its customers and has dedicated itself to implementing an advanced quality program. The ultimate goal being the creation of a high quality product with extended reliability for the customer. The result is reflected in Bucyrus? current product offerings and highlighted by the new 495HF electric rope shovels at Albian Sands mine.

May 1, 2003

By S. Aram

Concrete reinforcing requires coordination among many roles: structural engineer, estimator, detailer, fabricator, installer and others. The methods used to define and represent concrete reinforcement elements and assemblies in building information models is crucial in determining the efficiency of sharing data among BIM platforms and the effectiveness of using the carried data in production planning, fabrication and site work activities. Starting from the information items that are required to be provided by BIM platforms, as defined in earlier work, we have developed the Industry Foundation Classes (IFC) bound Concepts and Model View Definitions (MVDs) for concrete reinforcement. Furthermore, in coordination with software developers, we propose guidelines for best practices for concrete reinforcement modeling. Implementing these guidelines by software providers will improve reinforcement modeling with regard to various aspects of reinforcement products like geometric representation, placement, and property specifications. The proposed approach is selected as a way to improve functionality of the shared data for production planning, fabrication, project management, and site activities. Guidelines for assigning information to rebar type and instance definitions as well as to rebar elements and assemblies are provided. An efficient method of sharing geometry and property sets among rebar instances of a rebar array is also defined.

Aug 1, 2013

By J. Y. Kim

This paper presents a novel action recognition method for observing human workers using interactions between actions and related objects on an internal construction site. This method can be used to measure work rates for labour productivity monitoring. This monitoring is critical because the performance of a construction project is significantly impacted by labour productivity. However, construction sites are generally crowded with a large number of workers and objects. Such congestion disrupts the accurate, automatic recognition of construction workers? actions. This congestion is one reason that existing automatic action recognition studies of construction areas mainly focus on workers? actions themselves. However, the crowded conditions mean that sites could offer a great deal of clues that could be used for automatic action recognition. According to psychological studies, interactions clearly take place between human actions and related objects, such as between hammering and a hammer. Humans use these interactions to recognize actions or objects more accurately. On the construction site, workers, materials, tools, and equipment are carefully planned out ahead of actual construction. The categories of workers and objects are pre-defined and, as noted, specific interactions define relations between worker actions and objects. In this paper, the interactions are limited to human workers and their hand-held objects. Action recognition results can be combined with hand-held object information to improve recognition accuracy. With the limited interactions, experiments in this paper show a significant improvement in action recognition. This paper describes the utilization of these interactions to improve construction action recognition accuracy based on human skeleton data and 2D color video from Microsoft KINECT sensor.

Aug 1, 2013

By W. Beres, R. E. Miller, B. Shiari, L. R. Zhao

A dynamic multiscale simulation method has been developed to study the material scratching processes on nanoscale single crystals. The model simultaneously captures the atomistic mechanisms near the free surface and the long range mobility of dislocations and their interactions, without the computational cost of full atomistic simulations. The method also permits the simulation of system sizes that are approaching experimentally accessible systems, albeit in 2D. Simulations are performed on single crystal aluminum to study the atomistic details, surface evolution, and generation and propagation of dislocations for a variety of scratching depths at room temperature. Simulations demonstrate the power of the developed method in capturing both long-range dislocation plasticity and short-range atomistic phenomena during tool advance. Variations of scratching normal and tangential forces are investigated and related to plastic deformation and dislocations generation during the simulation process.

Jan 1, 2006

By Allan R. Punkkinen

Safe extraction of the valued ore resource in the deep levels of VALE Creighton Mine has progressed in a pillar-less fashion using vertical retreat, slot-slash and uppers retreat methods since the cessation of ?cut and fill? mining in the late 1980?s. Sequencing of the panel extraction and filling has been the key to successful exploitation of high stress orebodies at depth. In late 2010, discussions between the Operating Department and Creighton Ground Control revealed an opportunity to evaluate a trial primarysecondary sequence in the west end of the 400 Orebody at the 2340m horizon. To manage the trial primarysecondary project, a high level risk analysis and management of change was carried out to mitigate potential danger. As part of the requirements, an instrumentation project was conducted in the hanging wall and footwall bottomsills of the secondary panel and within the secondary panel itself. The extraction sequence was modeled with Map3D® software, confirming high stress levels with the advance of the primary panel. Enhanced ground support was installed based on modelling results. A key objective of the instrumentation project was to verify support system response to mining and to obtain knowledge in regards to the behavior of the stope. This paper describes the first time that this type of new innovative instrumented rockbolt technology had been used in a hard rock mining environment. Understanding of the physical deformation mechanisms of ground support in response to high stress conditions is the basis for an effective ground control strategy. The data played an important role in subsequent enhanced ground support system design at the mine and importantly, established the fact that the secondary pillar had not totally failed. Subsequent cavity monitor results helped establish that fact.

Jun 1, 2012

By DALE MacGREGOR, VERA TUREK

lndusmin Limited acquired the St. Donat quartzite deposit in 1967 to produce high-quality silica for use in the sandblasting and silicon carbide industries. The quartzite, of Grenville age, is highly friable and porous. This is due to numerous small, kaolinite-coated cavities in the quartzite; the cavities were formed through leaching, probably by rising hot solutions.

Jan 1, 1984

The tensile test results of as-cast A356.2 grain-refined alloy castings show that the tensile strength can be improved by strontium modification (`SrM'), superheating at 900°C OM, and melt thermal treatment of the Sr-modified alloy melt (`SrMTT'). Both SrM and SrMTT processes can greatly improve the ductility (percent elongation) of the as-cast alloy. During solution heat treatment at 540°C, eutectic Si particles undergo fragmentation, spheroidization, and coarsening, thereby affecting their morphology. The effects of solution heat treatment on the tensile properties of the variously treated A356.2 alloy castings can be summed up as follows: the yield strength of the castings is significantly improved after 8 h solution heat treatment due to the precipitation of Mg2Si, after which it remains more or less the same with the further increase in solution treatment time up to 80 h; the ultimate tensile strength is also greatly improved within the first 8 h of solution heat treatment and then remains at the same level thereafter, up to 80h of solution treatment. The improvement in UTS is attributed to Mg2Si precipitation, dissolution of Si within the aluminum matrix, and changes in the Si particle morphology (spheroidization). The ductility of the as-received grain refined non-modified (`NM'), grain refined and superheated at 900°C (`SH'), and melt thermal-treated grain refined (`MTT') A356.2 alloy castings can be improved considerably with solution heat treatment e.g. from ~6% in the as-cast non-modified casting to ~10% after 80 h solution treatment.

Jan 1, 2011

By A. J. Antony Chettupuzha

During a construction project, it is important to ensure that accurate and pertinent knowledge is delivered on time to appropriate personnel. The criticality of documents exchanged or referred to by various parties, evolves over the course of the project lifecycle. Determining the criticality of documents at different stages of the project can aid companies with managing the flow of information in an organized manner, while providing for the detection of potentially disruptive, erroneous material that could result in delays and costs. Therefore, it is crucial to determine documents which have the potential to disrupt a process (by virtue of being incorrect versions etc.) so that they may be isolated or prevented from entering or interfering with the active flow of information in a project, while also ensuring standard revisions of documents are recognized and accessed accordingly. Electronic Product and Process Management [EPPM] systems provide the capability to establish and map information flow between different parties in a construction project. Analyzing an EPPM system may yield information about the criticality of certain documents within an activity, as well as isolate characteristics peculiar to documents which can assist in risk mitigation. We propose methodology that identifies such critical documents.

Aug 1, 2013

By Jiachen Wang

Longwall top-coal caving mining is one of the major mining methods for extracting thick coal seams in China. The top-coal caving longwall mining was began to use in the 1980s in China, and got the rapid development. The development of the top-coal caving mining technology in China, the achievements and the theoretical aspects progress of this method are described in detail in this paper. And the main technical model of China's top-coal caving mining is introduced in this paper. This paper also introduces the application of large-cutting-height mining in China and the technical level it has reached.

Aug 1, 2013

By R. D. Brown

"Taxation tends to be a depressing subject. Taxes are unfair, taxes are too high and, above all, taxes are too complicated.In a recent address to the Canadian Tax Foundation, the author discussed in a rather more lighthearted way the possible causes of the complexity of the present Canadian taxation system. In order to provide an element of relief in this series of articles on taxation matters, extracts from these remarks are quoted below :"

Jan 1, 1976

By Eric D. Monrad

Supply chain simulation modeling is taking on a more prominent role in mining project planning and decision making. Transportation costs for the supply chain can form a significant component of the overall cost to provide product to the end customer. In recent years, computing power has increased, simulation software has advanced, and simulation specialists have become even better equipped to provide sophisticated analysis and recommendations. This has led to a virtuous cycle of owners expecting and supporting data-driven analytics, which drives further advancement. This paper discusses developments in supply chain planning and two case studies from recent simulation modeling analyses.

May 1, 2013

By J. M. Cooper

The HBMS reverb furnace in Flin Flon was originally designed in the late 1920s. Throughout the decades campaign life has been increased due to operational practices, technological changes and brick quality improvements. In recent decades the campaign life had been extended such that a complete rebuild was scheduled every 3 years. The latest furnace rebuild and start up has been after a campaign life of nearly 6 years. Brick construction methods and techniques along with furnace operational practices allow the present campaign to be double that of the historical campaign length.

Jan 1, 2007