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By R. M. de Carvalho

Empirical and phenomenological models of SAG and AG mills have dominated the scene for the last few decades, being used nearly every time a mill is scale-up or an attempt is made to improve its performance. However, in spite of their success, these models fail to describe the details of both the grinding environment and the breakage mechanisms. The result is a generally good track record, with a few – but very important – instances when these models fall short in their predictions, which can be very costly. Further, nearly all of these models require detailed calibration to industrial and pilot plant data, being costly in their application, although still with limited predictive capabilities. Recognizing these challenges, a new model framework has been proposed which overcomes the limitations of currently used models by coupling the microscale population balance model, the discrete element model and functions that describe internal classification at the mill grate. This model framework has already been applied to describe breakage in ball mills, with showing very promising results. However, in the case of SAG and AG mills a much greater level of complexity is involved in the model, given the interaction between the mechanical environment that is formed totally or, in part, by the ore itself, and the breakage response in the mill. The paper describes the model framework, demonstrating how it can address appropriately effects such as mill speed, mill filling and size distribution, on the response from the mill. Some of the advantages of the model are related to its intrinsic multi-component and dynamic nature, which allows simulating appropriately mixtures of ores of different competences in a transient manner.

Jan 1, 2012

By Kevin Azocar, Jim Hazzard

"Slope stability analysis is performed most commonly using limit equilibrium calculations or numerical models assuming a two-dimensional slice through an infinitely long slope surface. In areas such as open pit mining, where most slope surfaces are not planar, the importance of curvature becomes important due to the economic gains associated with creating a steeper slope. With advances in computing capabilities within the last decade, three-dimensional slope analysis can be performed within reasonable time frames. Some work has been done on the potential importance of curvature on slope stability, mainly assuming homogenous materials with a circular shear-failure mechanism. However, many open pit mines are excavated in jointed rock mass where a completely different set of failure mechanisms can be seen. Depending on the geometry and radius of the pit, the curved geometry may influence the factor of safety and failure behaviour compared to a two-dimensional slice.A series of numerical analyses were performed to investigate the effect of curvature on jointed rock slope stability compared to an equivalent two-dimensional slope analysis. By using discrete element method models, the influence of joint planes and interaction between distinct blocks can be seen. With a three-dimensional model, the effect of curvature can be combined with multiple joint sets at any orientation, which cannot be seen in a single slice. Numerous three-dimensional models are created, along with an equivalent unit-thick slice. The effect of curvature on a variety of different types of failure mechanisms is observed, and graphical relationships are created to quantify the difference between the three-dimensional factor of safety and the two-dimensional factor of safety based on the degree of curvature."

Jan 1, 2015

By H. Utsunomiya

Most magnesium alloy sheets show low deformability in rolling. Edge cracks and transverse fractures are common difficulties. In addition, rolled sheets show well-developed basal texture <0001>//ND. The texture causes high anisotropy in mechanical properties and low formability in subsequent metal forming. Differential-speed rolling, where the upper and the lower rolls rotate at different speeds, introduces shear deformation through the thickness. Not rolling texture but shear texture evolves in the sheet so that the asymmetric rolling can be a method of texture control. However the primary slip system of the hcp alloy, is basal, the shear texture should be also basal. Differences between the two basal textures, i.e., the rolling texture and the shear texture, have not been understood completely. In this study, conventional (same-speed) rolling and differential-speed rolling have been applied to commercial AZ31B sheets at 623K. Microstructures, textures and mechanical properties of the rolled sheets before/after annealing are compared. It is found that the basal texture is more pronounced by the asymmetric rolling. On the other hand, the asymmetric rolling is effective to decrease the grain size and the planar anisotropy.

Jan 1, 2006

By Adrian White

Agenda Overview of pastefill at Kidd Mine Pipeline wear and the need to monitor Steel Loop monitoring Steel Borehole monitoring Monitoring pipe linings

May 1, 2013

By M. Duncan

Lightweight, high-pressure cylinders for compressed hydrogen storage are essential components for fuel cell vehicles. Storage volume and mass are two key considerations. Current on-board hydrogen storage systems are based on a maximum pressure of 350 bar. While 350 bar systems are excellent solutions for many applications, some situations require higher storage densities due to space restrictions. As a result, significant research and development work has been expended by cylinder manufacturers, systems providers, testing agencies and automotive manufacturers to develop 700 bar systems with reduced storage volumes. Dynetek Industries Ltd. has proactively developed several 700 bar storage cylinders based on a seamless aluminum liner over wrapped with a carbon fiber composite. This paper presents the challenges and processes involved in the design, testing and certification for Dynetek Industries Ltd. 700 bar cylinders. This paper also provides reasoning for further volume and mass optimization of compressed hydrogen cylinders through the establishment of realistic cylinder usage parameters in standards. In particular, the overly conservative fill life requirement for cylinders is examined.

Jan 1, 2005

By Kan Xing

This paper introduces common detrimental consequences to the environment from mining in the Beijing West Mining Area. For example, ongoing mining operations can cause the following environmental deterioration: rock burst, roof rises, roof falls and inrush (Pit dash for ward water). Post-closure, after minerals resources are exhausted, the following environmental issues may remain: landslides (collapse, and mud-rock flow), dropping or exhausted water tables, water pollution, desertification and soil erosion, water accumulation, Slay endanger, ground subsidence, and causal factors in seismic activity. This paper analyzes this wide range of environmental consequences of mining, and offers a theoretical foundation to underpin a corresponding management scheme.

Aug 1, 2013

By I. Kirman, B. Waters

World wide applications for nickel use will be summarized and examples of those uses given. Nickel products are critical to many important aspects of modern society. These products are just as important for modern China as they are in other parts of the world. It is argued that future pattern of nickel use in China should be expected to be very similar to that in the rest of the developed world. Total use of nickel in products in China is already very large. In 2004, it was the largest market for stainless steel (nickel containing) in the world. A survey of Chinese stainless steel applications will be presented. Current high nickel prices have revived speculation about substitution, particularly for nickel containing stainless steels. The presentation will discuss some of the complicating factors that need to be taken into account when considering substitution. These factors are as valid in modern China as they are in other developed economies. Recent substitution efforts and the reaction to them will be examined. The Nickel Institute position regarding appropriate application of the various grades of stainless steel will be discussed. Price-motivated substitution in China, and elsewhere, will occur but it is argued that the extent will probably be limited.

Jan 1, 2005

By F. King, R. Sutherby, J. Been

With thousands of kilometers of buried oil and gas pipelines throughout the country, carrying flammable, high-energy hydrocarbons, the integrity and safety of this transportation and distribution network are paramount. The pipeline industry has the primary responsibility for pipeline safety and has in many ways taken the lead in dealing with safety issues. Over recent years, regulatory demands have increased, requiring operators to comprehensively evaluate their pipelines through indirect and direct inspections and to manage risk through integrity programs. Mechanistic and correlative models have been developed that assist in the prediction of pipeline integrity and the determination of reassessment intervals. These lifetime prediction models are based on decades of laboratory research as well as pipeline operating data, material data, and field monitoring data pertaining to soil conditions and CP. An overview is presented of an integrated approach towards the development of such models for the evaluation of external cracking and corrosion of transmission lines.

Jan 1, 2005

By F. Simon, A. Roth, M. F. Zaeh

Applying Friction Stir Welding in an industrial environment requires knowledge about the robustness of the welding process against imperfections in the joint line resulting from production deviations of the parts to be joined or from improper clamping devices. In this work the influence of gaps on the weld quality of friction stir welded butt joints of the aluminum alloy EN AW-5083-H111 is investigated in detail using the method Design of Experiments. As independent input variables, the rotation speed, the feed rate, the tilt angle, the lateral tool offset and the gap width were chosen. Tensile strength was selected as a measure for the joint quality. Moreover, the fundamental response variables of the FSW process, such as weld temperature, axial force and spindle torque, were recorded and integrated in the empirical process model derived by regression analysis. It was found that each response variable decreases with increasing gap width, whereas the largest impact was identified for the axial force and the temperature at the weld surface. In order to improve the joint strength for a given gap width, increasing the rotation speed and the tilt angle or lowering the feed rate, respectively, proved to be a suitable approach. However, interactions between the tilt angle and the rotation speed have to be considered.

Jan 1, 2014

By T. Gerritsen, C. Martinez, F. Stober, T Ma, J. R. Frias, M. Sedighy, J. Janzen

Electrode control systems regulate power by physically positioning electrodes. Due to the weight and inertia of the electrodes and hoist equipment, this is a relatively slow process where power fluctuations of less than a few seconds are not fully corrected. Nickel laterite AC furnaces operating in high voltage, shielded arc mode typically incur frequent power variations of approximately +/- 20% or more around the power set point. To provide enhanced power control, Hatch has recently supplied, at commercial scale, a thyristor-switched reactance system called an SPLC. The SPLC incorporates predictive control software to operate furnaces at the maximum transformer rating by reducing the large power swings experienced without the SPLC. The resulting higher average power enables higher production, without increasing transformer or power plant capacity. A 60 MW production version of the SPLC has been commissioned on Falconbridge Dominicana&apos;s laterite nickel furnace, yielding excellent results with a 3 to 1 reduction in power fluctuations.

Jan 1, 2005

By David J. McDougall

"The production of pig iron, wrought iron bars and castings in Quebec during the 18th and 19th centuries has been so closely identified by historians with Les Forges du St. Maurice on the St. Maurice River a few miles north of Trois Rivieres (Three Rivers), that one is sometimes left with the impression that it was the only iron works that ever operated in the province. There were however, about twelve others, one of which was so completely re-built that it should probably be considered as a separate entity. All but two were constructed after the midpoint of the 1800s, coinciding with the growing Canadian demand for ""charcoal pig"" for railway car wheels and castings for industry, and about half of them were technically, if not economically, successful. The misconception about Les Forges du St. Maurice may have come about either because of its long history of somewhat less than continuous production over a century and a half, or a tendency of Quebec historians to concentrate on events in the French-Canadian milieu, but whatever the reason, the other Quebec iron works have been generally ignored. All but one of the Quebec blast furnaces could be described as ""pre-industrial"" with capacities ranging between three and ten tons per day, the exception being the Radnor furnace built in 1892 with a maximum production of about 35 tons per day and an alleged capacity of 50 tons per day. Until a railway network was completed in the 1880s, the location of all the Quebec iron works except the Grantham Iron works was dictated by close proximity to adequate ore reserves because horse transport was of little use beyond a ten-mile radius. The other essentials of forest resources (mainly soft woods) for charcoal, limestone for flux and water power, were generally available except within a few miles on either side of the St. Lawrence River. Among the dozen iron works established in Quebec between 1732 and 1880, seven used bog iron ore in charcoal-fired furnaces. Five of these, including Les Forges du St. Maurice, were located on or near the St. Maurice River which enters the St. Lawrence River from the north, and two, the St. Francis Forges and the Grantham Iron works were on or near the St. Francis River which enters the St. Lawrence from the south. In a general way deposits of bog iron ore in the St. Lawrence lowlands of Quebec were contained within the limits of the post-glacial Champlain Sea, with many clustered along the flanks of the St. Narcisse recessional moraine which is crossed by the St. Maurice and other near-by streams, and the Drummondville recessional moraine which is crossed by the St. Francis River."

Jan 1, 1999

By T. Macpherson

ABSTRACT: Drawing on past research experience with sprayable polymer mine support agents (TSLs), Spray On Plastics Ltd. has developed a TSL ground support system called RockWeb. Using a relatively new polyurea polymer technology, RockWeb has been engineered to solve problems encountered underground with polyurethane liners by incorporating rapid curing, moisture insensitivity and superior physical performance. RockWeb possesses a unique, patented ability to be sprayed in a ?cobweb? like consistency allowing the applicator to span fissures in the rock, ensuring no initial defects in the liner, and maintaining design thickness over highly irregular surfaces. This ability, coupled with the high strength and elasticity of polyurea, allows RockWeb to mitigate rock movement through yielding, while maintaining intimate surface confinement. RockWeb provides reduction in logistics through the transport of 1/25 of the material quantities required for shotcrete, rapid deployment rates of as little as 30 minutes per round, and immediate return to the work area. This paper will discuss the technology and advantages of RockWeb as well as opportunities for overall mining cycle cost reduction. The safety benefits, as well as health and environmental considerations regarding application of isocyanate-based liners will also be discussed.

May 1, 2009

By José Carlos Marques

This paper addresses recent calls to study the role of the state in private regulation. Using an historical, organizational-field approach, I trace and explain the evolution of public debates and interaction of different forms of regulatory initiatives dealing with Canada?s mining industry. The empirical evidence presented calls attention to the interaction amongst different regulatory forms, as well as the conditions under which the state will encourage fragmented initiatives, rather than facilitate and catalyze regulatory strengthening and consolidation. As such, my analysis: problematizes the underlying assumptions used as a starting point by the growing literature on the role of the state in private regulation; connects and juxtaposes recent scholarship to more established literature on regulatory state failure and self-regulation. I also contribute to the discussion on Canada?s CSR policy, outlining the likely regulatory effects of the current policy framework.

Aug 1, 2013

By E. R. Rivenbark

"The coal handling plant represents an investment of about $100 million in coal handling and storage equipment. The coal receiving is done by a continuous ship unloader that can handle ships in the 60 000 T range at Q rate of 1750 /ph. A unique feature in the system is a stacker/reclaimer unit which will work inside a dome storage structure. The coal for the unit will include any low sulphur coal that can be delivered by sea at an economical price blended with New Brunswick high sulphur coal.ThE flue gas scrubber is a wet limestone system capable of 95% SO2 removal. The scrubber will utilize about 150 000 tonnes of limestone per year and will produce commercial grade gypsum by the forced oxidization method.IntroductionWith the need for new generating capacity being required, New Brunswick Power reviewed, in 1985, its options for the next unit. The study indicated that the most attractive option for New Brunswick Power would be a coal-fired unit capable of receiving imported coal at a sea port. The site selection process resulted in three site options being considered.The existing Coleson Cove and Dalhousie sites, and the Belledune site were considered. To meet load distribution needs, it was then decided that the unit had to be located in the northern section of the province, thus eliminating the Coleson Cove site. The Belledune site was selected because it had the capacity to have additional units added where as the Dalhousie site would have only been able to accommodate one unit"

Jan 1, 1994

By R. S. Jr. Stronach

"IntroductionThe property of Campbell Red Lake Mines, Limited, is in Balmer township, Red Lake area, Patricia portion of Kenora district, Ontario. It consists of a group of twelve claims which had been staked and re-staked a number of times before George W. and Colin A. Campbell staked them in 1944. Messrs. Brewis and White incorporated Campbell Red Lake Mines, Limited, in July, 1944, to acquire these claims from the Campbell brothers, and in November of the same year re-assigned their option on the controlling interest of the treasury shares to the Dome Exploration Company (Quebec), Limited, a wholly owned subsidiary of Dome Mines, Limited.A long known exposure of sulphides on the northeasterly portion of the property, which returned low gold assays, on sampling, was the only showing of interest at this time. However, Dr. H. C. Horwood's report and map of the district had recently been published and favourable structure W3.S indicated in Balmer township. It was on the strength of this showing and Dr. Horwood's report that Dome Exploration became interested in the property.Between. January, 1945, and April, 1946, a diamond drilling programme was carried out, with completion of sixty-one holes. Five holes proved the surface showing to hold no commercial interest, so routine cross-sectioning of the property from north to south was started. The fourth hole of the series returned excellent ore intersections and from that time on the programme changed to one of extending these values. The final results of the drilling showed that what is now known as the A zone has a continuous length of some 1,200 feet, a width of 4½ feet, and an overall grade of about 0.5 oz. gold per ton. There were many other intersections of ore grade outside this A zone which could not be successfully correlated .at that time, but underground work has opened many of them. It may be said here that practically all the work to date has been confined to the southeast claims of the property."

Jan 1, 1950

By P. J. Deveaux, M. J. Kreczmer

The Tartan Lake deposit 12 km northeast of Flin Flon, Manitoba, was discovered in March of 1984 during the investigation of a VLF anomaly. The discovery hole intersected 16.83 metres averaging 21 gm Au/tonne. Since then, 99 holes, over 21,000 metres, have been drilled outlining 419,491 tonnes grading 11.79 gm Au/tonne in a di stinct group of mineralized lenses referred to as the Main Zone. Three other mineralized zones are known on the property but no reserves have been allowed for these, the South , East and Base Line zones. The Main Zone consists of seven parallel, east-west striking, quartz lenses. The lenses dip steeply to the north and plunge steeply west to northwest. Lens number l strikes for 160m and extends vertically to the 90m level. Within th is lens there is a 60m interval of low grade materi al. Lens number 2 is located about 5-l0m within the foo twall of Lens number I. Near surface this lens stri kes for 40m, at 200m level the strike length increases to 200 m. To date the deepest mineralization on Lens 2 has been intersected at a vert ical depth of 527m. Five smaller lenses are located in the foo twall of Lens 2 , containing gold va lues similar to the two main lenses but erratically distributed. The South Zone, located 100m south of the Main Zone, strikes east-west fo r l00m above the 100m level. The East Zone, found 230m east of the Main Zone, strikes fo r 80m and may possibly be an ex tension of the South Zone. The Base Line Zone is located 275m south of the Main Zone. Sporadic, but very significant gold intersections have been obta ined1n all three zones. Gold-bearing quartz-ca rbonate tourmaline veins are generally confined to a silicous crystal tu ff hori zon. The crystal tuff exhi bits fi ve distinct types of alteration: silicification, sericitization, ca rbonati zation, chlorit ization and pyritization. Silicification has resulted in a perasive addition of silica and the generation of multiple quartz veins. Sericiti zation is restricted to the crystal tuff. All rock units are pervasively carbonatized . Ankerite is abundant in the quartz veins and within the shear zones, particul arly those located along the chilled margin of a nearby gabbro-diorite intrusion. Chloritization is widely spread th roughout the rock units, while pyritization fo rms a broad alteration halo associated with the orebody. Sulphide accesso ry minerals associated with the gold , whi ch fo r the most part appears to be free, are chalcopyrite and pyrite. Generally, the higher grade gold values are related to an increased content of sulphides in the qua rtz veins. The average sulphide content in the deposit is less than 5 %.

Jan 1, 1986

By Garry Biles, Ken Major, Raj Anand

"Prime Resources Group Inc. (Prime) commenced the Eskay Creek Mine operations in 1994 in northern British Columbia. The ore from the underground mine is crushed and shipped to smelters in Japan and Canada. The nominal production rate is 300 tonnes per day.Before commencing the above operations, preliminary evaluations for the high grade gold mine had indicated that an extremely complex metallurgical and chemical process flowsheet would be required to recover the economic metals. Subsequent to the metallurgical testing program, Prime identified markets for the untreated ore and initiated underground mining and ore transportation operations.Prime recently identified lower grade ore zones, which are less economic or uneconomic to mine and ship directly to the smelters. Test programs were initiated to evaluate processes for upgrading the ore to a marketable product. In 1997, Prime will complete the engineering and construction of a 150 tonne per day flotation plant to concentrate the gold and silver values for the NEX and 109 zones. The mine will then, in addition to the direct shipping of the shippable ore, ship concentrate from the millable ore. This paper discusses the development and design of the flotation plant.IntroductionThe Eskay Creek Mine is located in north-western British Columbia approximately 83 km north-west of Stewart, B.C. as shown in the location map Figure 1. Access to the site is provided by a restricted access gravel road from Bob Quinn Lake junction of highway 37, a distance of about 59 km. The work force at the mine is based on a two-week rotation schedule. Employees are flown from as far away as Vancouver to Smithers by commercial airlines and then from Smithers to the Bob Quinn airstrip by local charter. During poor weather conditions, transportation to site is by vans that take about six hours to travel the 450 km road distance."

Jan 1, 1998

By José J. Suárez

As pressure grows for commodity pricing, new mines are more difficult to develop, the stock markets demand better financial returns from mining companies, resources for the developing and operations are scarce, and developing countries in Asia, and Africa demand more metals, it is important that mining companies effect better utilization of capital to develop capital projects. In the last few years, the costs for Capital projects have been impacted by the following factors:

May 1, 2013

By J. H. . MORGAN

Talc-soapstone deposits exist in Patton Township of Quebec and have been mined by Bakertalc Inc. or its predecessors since 1938. The company produces products ranging from purified and micronized talc through to soapstone lumps. The deposits are found within serpentinite dykes and are zoned. Zoning grades from a serpentine core through zones of talcmagnesite, schistose talc and talc-chlorite schist be/ ore reaching the wall rock of quartz-sericite-chlorite schist. Talcmagnesite zones generally comprise 80 to 90% of the mined rock. The serpentinite dykes containing the talc probably were originally post-Ordovician peridotite of the same series that hosts the Eastern Townships asbestos deposits. Alteration of serpentine to talc-soapstone and magnesite apparently resulted through addition of silica and carbon dioxide along shears and fractures. Talc concentrations occur also at the intrusive contact between dykes and wall rock. The present Bakertalc Inc. operation at the Van Reel Mine is being worked from an inclined shaft 200 m below surface. The talc rock undergoes a variety of milling processes, depending on its particular market, be/ ore being bagged and shipped.

Jan 1, 1984

By J. Shanks

In 1920 the writer presented some notes, embodying his experience with storage-battery locomotives as main under-ground haulage-motors at Brazeau collieries. (1) Since that date these motors have stood up well to the test of maximum output and heavy overloads, having accomplished all that was expected of them. The notes presented in 1920 gave a brief description of the conditions under which these motors were working at Brazeau collieries, also the cost, per ton mile, of operating them. The cost per ton mile has since then been appreciably reduced, by working the locomotives nearly to capacity and under more ideal haulage conditions, on both shifts. It is not the intention of the writer to repeat what was written in 1920, but rather to give members the benefit of his experience in operating different types or designs of locomotives; to draw their attention to the drawbacks of some designs, and to the improvements made in some of the more recent storage-battery locomotives put on the market, as regards efficiency, upkeep, and safety. Because of their flexibility storage-battery locomotives have advantages over any other type of haulage, where grades are suitable to their use. The number in use in the mines in the United States has increased enormously during the past few years, and this method of haulage is, at the present time, attracting the attention of British and Continental mining engineers.

Jan 1, 1924