Search Documents

By Alessandro Navarra

Discrete event simulation provides a computational framework in which the use of smelting equipment can be analyzed and optimized, leading to the development of alternative modes of operation. Much of the complexity of copper and nickel smelters is centered on the converter aisle. These converters operate in parallel, produce batches, and set the tempo for the downstream operations. In practice, smelter staff schedule daily operations to coordinate the smelting furnaces and converters with downstream operations. Thus, a realistic simulation of smelter operations, over hundreds of days, should incorporate converter scheduling algorithms as presented in this paper.

Jan 1, 2014

By J. A. Rogers

"The Arthur W. White Mine (formerly Dickenson Mine) is a structurally controlled, hydrothermal gold deposit. A gold producer since 1948, it has, to December 31, 1990, processed 6.9 million (m) tons (T) of ore grading 0.45 ounces per ton gold (oz/T Au). As of December 31, 1991, Proven and Probable Ore Reserves were 3.2 m. T. at 0.32 oz/T Au. The mine is located just east ofPlacer Dome Inc. 's Campbell Mine, within the Cochenour-Gull.rock Lake deformation zone. It is situated on the hanging-wall side of a southeast-plunging anticline in a sequence of metamorphosed Archean volcanic, sedimentary and plutonic rocks of the Red Lake greenstone belt. Ore-bearing structures, found mainly within basaltic rocks, are brittle within greenschist-facies rocks to the northwest, but become more ductile toward the southeast, in amphibolite-facies rocks. Within and proximal to these structures, carbonate and arsenopyrite alteration decreases, whereas biotite, actinolite, pyrite and pyrrh otite all increase to the southeast.Ore and shear structures occur symmetrically about the northwest-trending, steeply southwest-dipping, flattening foliation . The three most common ore trends are on average: (A) northwest trending with a 55 degree to 85 degree dip to the southwest; (B) north-trending with a 40 degree to 50 degree dip to the west; and (C) due east-west-trending with a vertical dip. In general, the dominant direction of economic gold concentrations are explained and thus predicted by considering deformation style (brittle or ductile), rock anisotropies such as bedding and lithological contacts, and direction/magnitude of relative block movement. Direction ""A"" can be found adjacent to both right- and left-handed faults. Direction ""B "" occurs with dominantly right-handed systems and direction ""C"" is found with predominantly left-handed movement. Major faults active prior to, during, and after ore formation can have offsets in the order of 2500 feet. Movements along these faults were transpressive while their conjugate breaks were dilatant, thus creating zones for alteration and ore solution emplacement. A series of faults , each with offsets up to 30 feet were established under lower temperature brittle conditions during late- to post-ore formation. In more complex zones, formed during more ductile deformation, these faults controlled the localized geometry and, thereby, the depletion and enrichment of ore shoots, causing a high nugget effect.Although an important aspect of production planning and monitoring, grade control is also very important within a complex ore zone so that the nuggets are not missed. Detailed observation of structure at the hand-sample scale and detailed mapping at the stope scale give valuable clues to interpreting the structures on a mine-wide scale. Determining the relative movement along fault structures is very important so that using an action-reaction- type logic, potential dilatant areas can be predicted and targeted for development and diamond drilling."

Jan 1, 1992

From 1999 to 2008 rock related accidents accounted for 75 fatalities, nearly 6,000 injuries and almost 14,000 incidents (Pappas and Mark, 2011). Clearly this shows that rock related safety on coal mines remains a serious issue and more effort is needed to address this hazard. This paper reviews support design considerations and monitoring needed to improve rock related safety in room and pillar coal mines in the USA. From the present study design considerations continue to evolve and improvements in technology and a better understanding of failure mechanisms and methods to prevent these failures from occurring are in place. At first glance, the design of safe and efficient underground openings appears simple until the designer begins to realize the complexities and variability of geometries, geology, loading and stress influences, support designs and other factors such as corrosion and economics. Ultimately the goal of all designs is to ensure that it can be completed safely, last for the duration of the design life and it is economically feasible.

Aug 1, 2013

By K. E. Harley, M. J. Whiting, T. J. Sabin, E. M. Ryan, J. F. Watts

"Wire and Arc Additive Manufacturing (WAAM) has the potential to enable a very significant reduction in buy-to-fly ratio compared to conventional manufacturing through the ability to build near-net shape components. Components manufactured from AA 2319 by WAAM can exhibit significant levels of porosity. There is also a variation in the physical appearance of the surface deposit sometimes found on such components. This deposit is similar to those observed on aluminium joined by MIG and TIG welding processes. It has been suggested that both the bulk porosity and the surface deposit are caused by hydrocarbon-based lubricant on the feedstock wire. An established correlation between surface deposit and porosity would offer valuable insight into WAAM products and enable early interventions in quality control or process monitoring based on visual examination. The relationship between the nature of the surface deposit and porosity has been studied for AA 2319 WAAM components manufactured using different wire batches. Evidence is presented to support the assertion that (i) there does not appear to be a relationship between surface deposit coverage and porosity, (ii) batch-to-batch variability in feedstock wire affects porosity. This study has led to a better understanding of the cause of porosity in WAAM components.INTRODUCTION There is a high cost associated with conventional, subtractive manufacturing because of the high ‘buy-to-fly’ ratio, a measure of the initial material bought compared to the material found in the finished part (Allen, 2006; Yilmaz & Ulga, 2016). A typical aerospace product may have up to 90% of the purchased billet of forging machined away which is cost inefficient and high in material waste. Wire and Arc Additive Manufacturing (WAAM) has the potential to reduce costs and lead time. Robotically controlled weld torches rapidly deposit feedstock wire in layers to build large near-net shapes with mechanical properties similar to those of conventional manufactured parts (Sequeira Almedia & Williams, 2010; Martina et al., 2012; Ding et al., 2015; Williams et al., 2015). A high level of porosity variation has been observed in aluminium WAAM parts (Cong, Ding & Williams, 2014; Gu et al, 2016) which can result in a range of material properties (Rudy & Rupert, 1970). This leads to difficulties in regards to standardisation and qualification of process and parts. In order for WAAM to be used commercially, porosity will need to be understood, monitored and reduced to a reproducible acceptable level or eliminated."

Jan 1, 2018

WMS an Operation Service and Tool WMS is a the new SNC-Lavalin solution to complete and support your site?s operation. It targets phases in the project cycle including mechanical completion, pre operational verification and commissioning. The goal is to track phases completion and electronically deliver a plan with hand over documents.

Aug 1, 2013

By R. O. Grieve

"IntroductionCALEY (1945) and Evans (1950) pointed out that certain instances of convergence between Devonian and Silurian horizons, frequently evident in wells drilled for oil and gas in Ontario, appear to be related to local thinning of salt beds in the Salina formation and they suggested that leaching of the salt beds may have occurred. Exploratory drilling by Imperial Oil Limited since 1945 has brought to light several examples of structures similar to those discussed by Caley and Evans. The writer has had the opportunity to examine cuttings and data from wells which penetrated these structures and the attempt to interpret them in the light of the theory of leaching and subsidence proposed by Landes ( 1945a) to explain the marked brecciation and deformation of Upper Silurian and Middle Devonian sediments which crop out in the Mackinac Straits region of northern Michigan has led to the observations presented in this paper."

Jan 1, 1955

By Zhigao Xu, Ruan Chi, Zhenyue Zhang, Yaoyang Ruan, Zhengyan He

Weathered crust elution-deposited rare earth ore is a specific rare earth resource in China that is rich in middle and heavy rare earths. From surface to bottom, the weathered crust elution-deposit rare earth ores can be divided into humic layer, completely weathered layer, partly weathered layer, and bedrock. The exchangeable rare earth ions mainly exist in the completely weathered layer and partly weathered layer, and the exchangeable aluminum ions mainly exist in the humic layer. A novel solution injection method for use in the in-situ leaching technology of weathered crust elution-deposit rare earth ores was put forward based on the different distributions of RE3+ and Al3+ in the four layers. Avoiding the humic layer, only the completely weathered layer and partly weathered layer were leached by controlling the height of the leaching solution liquid level. In this way aluminum, the primary impurity in the RE leaching solution, can be decreased and the purity of the RE product can be improved. Meanwhile, the choices of available leaching reagents were broadened and the possibility of landslide disasters could be reduced.

Jan 1, 2014

By S. F. Dudka, T. Dang, M. L. Wong

Abstract - The Nui Phao W-F-Cu-Au-Bi deposit is located in one of the poorest regions of northern Vietnam. The deposit is currently undergoing a pre-feasibility study by Tiberon Minerals Ltd., with a view to developing what would be the largest WO3 mine and one of the five largest fluorite mines in the world. The project is being planned in close compliance with World Bank and national guidelines for environmental and social protection. Development of the mine is anticipated to bring the following benefits: remediation of serious pre-existing environmental conditions (natural and anthropogenic heavy metal contamination and acid rock drainage); provision of employment and training, and thereby wealth, to local communities; significant tax and royalty payments to government, which will be reinvested as social spending; and development of municipal and industrial infrastructure to build sustainable post-mining communities. The role of governments at all levels is critical in guiding and facilitating this process. This paper was written prior to development of the mine, and relays the intentions of the developers. Future studies will be needed to evaluate the degree of attainment of sustainable development objectives, both during mine operation and after closure.

Jan 1, 2003

By Lihong

A series of Fe2O3-elimination experiments were conducted on feldspar samples from Tangshan Stone?powder Plant. These experimental methods include scrubbing desliming, flotation,rod milling and high gradient magnetic separation. Some technical factors of feldspar concentration and a new technological flow?sheet of ceramics raw material concentration were put forward.

May 1, 2003

By S. Castro

Hydrolysis of metallic ions depends on pH and the products of hydrolysis either activate flotation or can lead to inadvertent activation of gangue particles, but can also depress flotation of valuable components. One of the most recently studied topics is the use of seawater in flotation. Seawater is a concentrated NaCl solution (about 0.6 mol/L) that also contains considerable amount of Mg2+ and Ca2+ ions. The hydrolysis products of Mg2+ strongly depress flotation of molybdenite over the pH ranges over which they form in the process water. This effect can be eliminated by removal of hydrolysing ions from the process water or by carrying out the flotation at the pH over which such a hydrolysis can be avoided. The former can be exemplified by prior precipitation of the harmful hydrolysing ions as, for example, in the University of Concepcion Patent. The latter can be exemplified by the use of metabisulfite to depress pyrite in the flotation of Cu-Mo sulfide ores in seawater, the process that is carried out at much lower pH, which avoids formation of Mg2+ hydrolysis products.

Jan 1, 2017

By H. L. Cameron

General Statement In July, 1948, experimental aerial photography o shallow water zones on Northumberland strait was carried out by the Nova Scotia Research Foundation. This work was designed to test the feasibility of aerial photography for coastal surveys o various types, including seaweed and bottom detail surveys. In the course of the work at Lismore, undersea faulting was noted visually and was later clearly apparent in the photographs. In order to prove beyond doubt that the lineations photographed are actually faults, a ground check was made, and terrestrial stereoscopic photographs were obtained of these features where they intersect the shore line. There can be no doubt of their nature, and the type of faulting is probably thrusting due to compressive forces. This is indicated by the successive right- and left-hand displacements on intersecting faults. The age of the fracturing is post Lower-Pennsylvanian (Lismore) and is correlated with similar compression faulting in western Cape Breton. As far as can be ascertained, this is the first time that subsea faulting has been photographed, though it is quite possible that similar structures have been observed elsewhere. Location and Area Lismore is on Northumberland strait, approximately thirty-five miles east of Pictou (see index map, Figure 1). The area mapped from aerial photographs (Figure 2) is a strip approximately two miles long by a quarter of a mile wide. Figure 3 shows a stereo-pair of the aerial photographs used to construct this map. The terrestrial stereoscopic photographs (Figure 4) show one of the faults.

Jan 1, 1949

By Guichao Wang, Geoffrey M. Evans, Graeme J. Jameson

"In this paper we present a new method for studying the detachment of particles from bubbles in a rotating turbulent eddy. The eddy is formed in a wall cavity in a two-dimensional water tunnel with transparent walls. When water flows through the tunnel, a vortical flow field develops in the cavity. The properties of the eddy can be modulated by changing the free-stream velocity of the water in the tunnel. Bubbles are pre-loaded with one or more particles in a fluidized bed flotation device located beneath the vortex cavity. Loaded bubbles are released one at a time into the cavity, and the motion of the bubbleparticle aggregate is studied using a high-speed video camera. The diameters of the particles and the bubbles, and the number of particles initially attached to the bubble, can be varied. The trajectories taken by the bubbles are quite complicated. In some cases, the bubble moves to the centre of the eddy, and particles rotate around its axis. If the rotational speed is sufficient, particles may detach due to centrifugal force. However, other modes were observed, including inertial detachment due to rapid changes in direction of the surface of the bubble, because of changes in trajectory of the bubble as a whole, or because of pulsations and oscillations of the bubble surface. Clusters of bubbles held together by particles were seen to form and reform. In the traditional explanation for the detachment of particles in flotation cells, it is assumed that particles detach from bubbles rotating in an eddy due to centrifugal force (Schulze, 1977). Although the conditions assumed in Schulze's theory may exist, it is only one of a range of phenomena that can lead to the detachment of particles from bubbles in a turbulent vortex.INTRODUCTIONThe recovery of particles by flotation methods is dependent on the particle size. The recovery in the existing flotation machines reaches a peak for particle size, typically in the range of 20 to 100 µm. This size range varies as a function of the particle’s properties (type and composites). For coarser particles, the recovery drops very quickly (Gaudin, Groh & Henderson, 1931; Jowett, 1980). If the upper size limit can be increased for flotation, dramatic savings in the grinding energy can be achieved."

Jan 1, 2016

By Michael L. Free, Shukla. Abhijeet

The short-circuiting tendency of a copper electrowinning cell (EW) based on the roughness of cathode deposits was investigated with varying parameters such as Cu concentration, guar concentration, current density, and temperature. A bench scale EW cell was set up to produce copper under conditions similar to industrial Cu EW. In addition, a statistical analysis and finite element analysis were performed to analyze the deposited thickness, surface roughness and maximum feature height. Interaction data for the cathode deposits suggest that current density and Cu concentration together affect the roughness of deposit more than the combined effect of guar and temperature. Model predictions of roughness were similar to experimental values. The predicted time to short-circuiting was similar to the measured time. This study provides an industrial relevant baseline against which new operating parameters can be compared.

Jan 1, 2014

By G. Roy

Interest in metal-hydrogen systems can be manifold. Small amounts of hydrogen adsorbed by elemental metals and alloys usually result in strong changes in the physical and mechanical properties of engineering materials. Overwhelmingly, these changes, viz. hydrogen embrittlement, are considered deleterious with respect to structural performance of engineering materials. However, the changes, often studied by metallurgists and metal physicists, can present new possibilities and applications. A prominent example is the recent interest in safe, solid-state hydrogen storage in metallic lattices. In a new laboratory in MTL, Ottawa, a study has been initiated to investigate the effect of "micro- and macro- alloying" of Al and Mg powders with hydrogen (in high-energy mechanical alloying mills) on plastic deformation in metal and metal hydride structures. It is anticipated that high-rate impacting and subsequent grain refinement in the mill will have an effect on hydrogen storage capacity in lightweight magnesium and aluminum alloys. First examination of the state-of-stress by X-ray diffraction in high-rate milled, nanostructured pure aluminum, aluminum milled with a solid surfactant, and aluminum or magnesium alloy milled with hydride and/or gas hydrogen will be presented.

Jan 1, 2005

By J. M. B. Scarborough

This paper deals with measures taken to maintain effective operation of heavy-duty equipment in open-pit mining. at Pine Point, N.W.T., during periods of extreme cold weather. The points covered include equipment modifications designed to improve cold-weather performance, effective lubrication of machinery that is vulnerable to extreme cold and operating procedures designed to prevent equipment damage.

Jan 1, 1966

Arguably the SMC Test® has become the most popular laboratory hardness test in the world with over 17,000 tests having been completed to date, covering over 650 different ore bodies. It is now routinely used in design, optimisation and orebody profiling projects. The test is unique in that from relatively small amounts of drill core it simultaneously provides parameters that are used in simulation modelling of AG/SAG and crushing circuits as well as work indices that are used in power-based equations for predicting the specific energies of AG/SAG/Crushing and HPGR circuits. The very large data base that has been accumulated has provided the opportunity to study the differences in variability from deposit to deposit. This paper describes and discusses the trends that have become apparent from the study of this data base. Recommendations for appropriate selection of sample numbers are also made which are based on these trends.

Jan 1, 2012

By J. J. Benitez

MIBC (methyl-isobuthyl carbinol) was previously shown to enhance significantly sylvite flotation when used at the stage of preparation of amine dispersions. In this paper Atomic Force Microscopy (AFM) is used to study the effect of MIBC on deposition of octadecylamine (ODA) on the surface of mica. The AFM images indicate that amino terminated, and therefore hydrophilic, deposits of ODA are observed on the mica surface in the ODA dispersions free of MIBC. In the presence of MIBC a methyl terminated (hydrophobic) monolayer is obtained on the mica surface. The transition between the monolayer and bilayer phases is due to the presence of MIBC. Experiments carried out in distilled water reproduced the results obtained from the brine. Working in pure water instead of brine simplifies the preparation conditions and the analysis by AFM.

Jan 1, 2006

By C. Larsen, R. A. Walker, A. Voth, C. Daoust

"The 3000 t/d mill at Hernia Gold Mines Inc. was commissioned in March, 1985. By Canadian standards the concentrator is highly automated, however, unlike the retrofit systems in many other plants, the Hernia process control system was installed during plant construction. This paper describes the Hernia control system beginning with system development (justification, architecture, start up, etc.), proceeding to current applications (crushing, grinding, leaching, etc.) and finally discusses some of the short term objectives for system improvement.INTRODUCTIONThe Hernia Gold Mines Inc. operation is located in the Marathon area of Northwestern Ontario. Controlled by Noranda Minerals Inc. (50.1 %), the cost of bringing the mine into production was nearly $300 million. A unique feature of the mine development was the extraordinarily short elapsed time of three years from Noranda's initial involvement to the start of milling operations. Additional background information on this project can be found in the trade literature (e.g. Tinter (1986). Scales (1987).)The Hernia concentrator is designed to process 3000 tpd of ore and commenced operation in March, 1985. Figure 1 provides a general plant flowsheet indicating the major circuits. Typical annual production statistics are included on the figure and these have been extrapolated from the available 1987 year-to-date data. Larsen and Tessier (1986) have previously described the operational aspects of the mill.In a metaphorical sense, the Hernia concentrator is like the traditional bride, ""wearing something old (e.g. the cyanide leach process), something new (e.g. a plant wide digital control system installed during construction), something borrowed (e.g. crushers from Gaspe) and something blue (e.g. the cladding on the surface buildings). While the prospect of fully undressing this bride is of considerable interest, here we choose to focus on something new. In particular, we choose to examine the process control system in some detail since Hernia is one of Canada's more highly autcmated gold mills. The control system is of interest because it has received suostantial credit for maximizing metal production and minimizing operating costs. With reference to the latter, it is worthy of note that Hem lo reports recent operating costs of less than $100 U.S./oz."

Jan 1, 1988

By I. Takahashi

Recently, electronic devices have become smaller for some kinds of electronic devices, thermal dissipation and electrical conductivity of conventional Fe based alloy becomes insufficient. We selected the Cu-Fe based alloy CDA19400 and optimized the wire manufacturing process. Precipitates during aging treatment were observed by TEM. The size and distribution of the precipitates varied according to solution treatment temperature. With solution treatment at 950°C, the precipitates of y-Fe as fine as 10 nm were distributed dense in the copper matrix with coherency. For the solution treatment at 750°C, y-Fe of approximately 200 nm was observed. Comparing heat resistance of drawn wires, the material at 950°C treatment was superior. Electrical conductivity decreased from 63% IACS upon aging to 29% IACS by drawing. It is considered as particular phenomena for wires where materials are drawn with high reduction ratio. By the optimized manufacturing process, we successfully developed a new wire that has superior in strength, thermal conductivity, electrical conductivity, heat resistance and repeated bendability.

Jan 1, 2007

By Jeff Bird, Xijia Wu, Prakash C. Patnaik

"Prognosis and health management (PHM) is an evolving suite of technologies intended for application to the life cycle management (LCM) of mission/safety critical systems, with anticipated results, which will: - Reduce life cycle cost - Enhance operational safety and readiness - Assist in maintenance decision-making - Enable autonomic logistics While it is emphasized in the United States that future multi-mission fighter aircraft such as Joint Strike Fighter (JSF) must have PHM capabilities, Canadian initiatives also recognize the need to implement such schemes for future and legacy military and civil aerospace systems. With respect to four major technology areas of PHM, i.e., i) advanced sensors, ii) data analysis and fusion, iii) life consumption evaluation, and iv) predictions with reliability/risk assessment, there has been advanced technologies developed by NRC and others within Canada: - Aircraft/engine instrumentation and airborne data recording systems - Signal analysis and data fusion - On-line engine health monitoring - Physics based models for engine material failure modes and life prediction - Autonomic crack growth analysis for damage tolerance of engine components - Mission severity analysis algorithm - Probability, reliability and risk assessment This presentation reviews the above technologies in relevance to PHM, emphasizes the need to have physics based models and outlines the future R&D needs for integration and implementation of these technologies suitable for the advanced and legacy aircraft."

Jan 1, 2004